Will Air Taxi Become a Reality? Will it ‘Elevateᾠthe Future of Transportation?
While integrating autonomous features in modern vehicles, leading auto companies are exploring the future of urban mobility in the aviation industry.
The emerging concept of air taxis reflects the dramatic transformation that is underway in the automotive industry.
With a mounting number of cars on roads, especially in urban areas, the transportation industry is undergoing a crisis with traffic management among many other issues.
Consequently, amidst the current revolutionary inventions in fully autonomous vehicles, air taxis are evolving as a whole new class of automobiles that is poised to metamorphose the future of mobility.
This is triggering automakers to foray into the urban air mobility (UAM) ‘landscapeᾬ ultimately fueling innovation in designs of air taxis.
or an e-air taxi conveys an impression from fiction, the reality is- Air taxis are nearing commercial availability.
This article dives into the reality of ongoing research and innovation activities in UAM and how they can bring the future of air taxis closer than anybody ever imagined.
The Revolutionary Concept of Air Taxi: Reality or Fiction?
The founder of The Ford Company ᾠHenry Ford envisaged the invention of flying cars back in 1940, and eighty years later, the world is ready to witness his prediction coming true.
A convergence of next-generation technologies is creating a promising future for UAM and air taxis with practicability and commerciality.
The heightened need for faster, cleaner, safer, and more affordable modes of transportation is triggering automakers to explore the potential of the vertical takeoff and landing (VTOL) technology in the evolution of air taxis.
Furthermore, with the advent of state-of-the-art battery technology, the evolution of electric VTOL (eVTOL) is enabling automakers to bring three-dimensional electric mobility in reality.
In the coming years, the convergence of the automotive industry and electric aviation industry is expected to support in making air taxi a ground reality!
are expected to have a paramount impact on the adoption of eVTOL technology in air taxisᾠfuturistic designs.
What is Happening in the Industry?
A mounting number of automakers and leading players in the shared mobility industry, as well as the aviation industry, are entering the global market for air taxis to gain the first mover’s advantage.
Uber, Porsche, and Boeing are among the front-runners in the air taxi market that are investing heavily in their models of autonomous air taxis to improve their safety features as well as affordability.
Though the number of competitors is small in this space for air taxis, soon the race to the skies is expected to get more competitive with time, as new businesses are poised to sprout up in this market.
The first successful flight of the CityAirbus, which uses the eVTOL technology, was realized in May 2019.
The company’s plan to commercialize the air taxi models for Vahana and City Airbus by 2020 and 2023, respectively.
, which unveiled its on-demand air taxi service with a five-seater prototype in May 2019.
Lilium Jet ᾠthe company’s all-eVTOl device ᾠcarries the capacity to complete long journeys within the range of 300km.
The company announced in May 2019, that the next milestone for its new air taxi will be to achieve a transition from vertical take-off to horizontal flight and to commercially launch an emission-free air taxi by 2025.
that has introduced its fourth-generation eVTOL air taxi named the VoloCity, in 2019.
It is a two-seater, 18-rotor eVTOL device with a top speed of around 70mph and a range of approximately 35km.
The company announced that its next goal is to focus on developing a suitable infrastructure and ecosystem with an efficient air traffic control system.
The number of active participants in the world’s air taxi market is increasing at an impressive rate, yet some significant challenges are making the world doubt the viability of the concept of air taxi.
Hurdles in Making Air Taxis a Reality
established by international bodies such as the European Union Air Safety Agency (EASA).
Though many governing bodies are welcoming the new air taxi modules, stringent regulations on their deployment and safety will continue to influence manufacturersᾠstrategies.
also continue to remain the top technological challenges for stakeholders in the air taxi market.
is converging with the electronics & telecommunications and Information Technology (IT) industries to enter the future of fully electric and driverless vehicles on as well as above the ground.
Eventually, the ongoing research and development technologies will continue to reiterate the fact that, the sky is the limit for innovations in the air taxi industry!
tutorial/pi-filter-working-application-circuit-design-tips
Pi Filter - Overview, Working, Construction, Application and Design Tips
In low pass filter application, Pi filter also called the Capacitor input filter as the capacitor stays across the input side in low pass configuration.
Pi Filter as a Low Pass Filter
When a Pi filter is designed for a low pass, the output remains stable with a constant-k factor.
consists of two capacitors connected in parallel followed by an inductor in series forming a Pi shape as shown in the image below
to block unwanted high frequencies.
for your application.
Cut off frequency(fc) = 1/(LC)1/2
Value of the Capacitance is (C) = 1/Z0fc
Value of the inductance (L1) = Z0/fc
Where, the Z0 is the impedance characteristic in ohms and fc is the cut off frequency.
Pi Filter as a High Pass Filter
to pass.
It is also made using two types of passive components, two inductors, and one capacitor.
In low pass configuration the filter is designed as two capacitors are in parallel with an inductor in between, but in high pass configuration, the position and the quantity of the passive components get exactly the opposite.
Instead of a single inductor, here two separate inductors are used with a single capacitor.
image is showing the filter in high pass configuration, and not to mention the construction is also looking like a symbol Pi.
The construction and the component values of the Pi filter can be derived from the below equation ᾍ
Cut off frequency (fc) = 1/4(LC)1/2
Value of the capacitance is (C) = 1/4Z0fc
Value of the impedance (L1) = Z0/4fc
Where, the Z0 is the impedance characteristic in ohms and fc is the cut off frequency.
Advantages of the Pi Filter
The output voltage across the pi filter is quite high making it suitable for the most power related application where high voltage DC filters are required.
Configured as a low pass filter In DC filtration purposes, Pi filter is an efficient filter, to filter out unwanted AC ripple coming from a bridge rectifier.
The capacitor provides low impedance in AC but a high resistance in DC due to the effect of capacitance and reactance.
Due to this low impedance across AC, the first capacitor of the Pi filter bypasses the AC ripple coming from the bridge rectifier.
The bypassed AC ripple goes into the inductor.
The inductor resists the changes of current flow and blocks the AC ripple which his further filtered by the second capacitor.
These multiple stages of filtering help to produce a very low ripple smooth DC output across the Pi filter.
In a controlled RF environment, where higher frequency transmission is required, for example in the GHz band, High-Frequency Pi filters are easy and flexible to make in the PCB using just PCB traces.
High-frequency Pi filters also provide surge immunities more than the silicon-based filters.
For instance, a silicon chip has a limit of voltage withstand capacity, whereas pi filters made using the passive components have much more immunity in terms of surges and harsh industrial environments.
Disadvantages of the PiFilter
Other than the RF design, High current draw through a Pi filter is not advisable since the current has to flow through the Inductor.
If this load current is relatively high, then the wattage of the Inductor also increases making it bulky and expensive.
Also, the high current through the inductor increases the power dissipation across the inductor resulting in poor efficiency.
Another major problem of the Pi filter is the large input capacitance value.
Pi filters require high capacitance across the input which became a challenge in space-constrained applications.
Also, high-value capacitors increase the cost of the design.
Pi filters are not suitable where load currents are not stable and constantly changing.
Pi filters provide bad voltage regulation when load current drifts a lot.
In such an application the filters with an L section are recommended.
Application of Pi Filters
Design as shown below.
Generally, Pi filters are directly connected with the bridge rectifier and the output of the Pi filters is referred to as the High Voltage DC.
The output DC High Voltage is used for the Power supply driver circuitry for further operation.
from the high switching frequency across the driver circuit.
if used in Power Electronics Application.
and before RF amplifiers.
However, in maximum cases where very high frequency, such as in the GHz band is used, Pi filters are used in the signal transmission line and designed using only PCB traces.
The above image is showing PCB trace-based filters where the trace creates inductance and capacitance in very high-frequency applications.
Other than the transmission line, Pi filters are also used in RF communication devices, where modulation and demodulation take place.
Pi filters are designed for a targeted frequency to demodulate the signal after receiving in the receiver side.
High pass Pi filters are also used to bypass targeted high frequency into the amplification or transmission stages.
Pi-Filter Design Tips
To design a proper Pi filter it is required to compensate proper PCB design tactics for trouble-free operation, these tips are listed below.
Thick traces are required in the Pi filter layout.
Isolating the Pi filter from the power supply unit is essential.
The distance between the input capacitor, inductor, and the output capacitor is needed to be closed.
The Ground plane of the output capacitor is needed to be directly connected to the driver circuit via a proper ground plane.
If the design consists of noisy lines (Such as high voltage sense line for the driver) that is need to be connected across High voltage DC, it is required to connect the trace before the final output capacitor of the Pi filters.
This improves noise immunity and unwanted noise injection across the driver circuitry.
In RF Circuit
The component selection is a major criterion for the RF application.
The tolerance of the components plays a major role.
A small increase in the PCB trace could induce inductance in the circuit.
Proper care should be taken for inductor selection by considering PCB trace inductance.
The design should be made using proper tactics to reduce stray inductance.
Stray capacitance is needed to be minimized.
Closed placement is required.
Coaxial cable is suitable for the input and output in the RF application.
article/driver-assistance-to-driver-replacement-the-cognitive-vehicle-is-built-upon-high-integrity-sensor-data
Driver Assistance to Driver Replacement: The Cognitive Vehicle Is Built Upon Foundational, High Integrity Sensor Data
It’s the moonshot of our time.
From sensors to artificial intelligence (AI), the classic electronics supply chain has formed a collaborative matrix dedicated to making autonomous vehicles safe.
To that end, there is much to be done in hardware and software development to ensure drivers, passengers, and pedestrians are protected.
While machine learning and AI have a role to play, their effectiveness depends upon the quality of the incoming data.
As such, no autonomous vehicle can be considered safe unless it is built upon a foundation of high performance, high integrity sensor signal chains, to consistently supply the most accurate data upon which to base life or death decisions.
Like the original moonshot, there are many obstacles on the road to safe autonomous vehicles.
Recent high profile incidents involving self-driving vehicles feed into the nay-sayer narrative that vehicles and the environments in which they operate are too complex, there are too many variables, and the algorithms and software are still too buggy.
For anyone who has been involved with compliance testing to ISO 26262 Functional Vehicle Safety, they’d be forgiven for being skeptical.
And that skepticism is supported by charts comparing the number of physical miles driven to the number of disengagements from the autonomous mode for five autonomous vehicle companies testing in Silicon Valley in 2017 (Figure 1).
Figures for 2019 have yet to be compiled, but reports for individual companies are available online.
However, the goal has been set and the imperative is clear: vehicle autonomy is coming, and safety is paramount.
The unofficial 2018 California autonomous vehicle Department of Motor Vehicles (DMV)numbers show that the number of disengagements per mile is decreasing, which also shows that the systems are getting more capable.
However, this trend needs to be accelerated.
Putting collaboration and new thinking first, automotive manufacturers are talking directly to silicon vendors; sensor makers are discussing sensor fusion with AI algorithm developers; software developers are finally connecting with hardware providers to get the best out of both.
Old relationships are changing, and new ones are forming dynamically to optimize the combination of performance, functionality, reliability, cost, and safety in the final design.
End to end, the ecosystem is pursuing the right models upon which to build and test fully autonomous vehicles for quickly emerging applications such as Robo-taxis and long-haul trucking.
Along the way, higher degrees of automation are being achieved rapidly as a result of improvements in sensors that push the state of the art in advanced driver assistance systems (ADAS).
These sensor technologies include cameras, light detection and ranging (lidar), radio detection and ranging (radar), microelectromechanical systems (MEMS), inertial measurement units (IMUs), ultrasound, and GPS, which all provide the critical inputs for AI systems that will drive the truly cognitive autonomous vehicle.
Cognitive Vehicles Foundational to Predictive Safety
Vehicle intelligence is often expressed as levels of autonomy.
Level 1 (L1) and L2 are largely warning systems, while a vehicle at L3 or greater is empowered to take action to avoid an accident.
As the vehicle progresses to L5, the steering wheel is removed and the car operates fully autonomously.
In these first few system generations, as vehicles start to take on L2 functionality, the sensor systems operate independently.
These warning systems have a high false alarm rate and are often turned off since they are a nuisance.
To achieve fully cognitive autonomous vehicles, the number of sensors increases significantly.
Additionally, their performance and response times must greatly improve (Figure 3, Figure 4).
With more sensors built into vehicles, they can also better monitor and factor in current mechanical conditions, such as tire pressure, change in weight (for example, loaded vs.
unloaded, one passenger or six), as well as other wear and tear factors that might affect braking and handling.
With more external sensing modalities, the vehicle can become more fully cognitive of its health and surroundings.
Advances in sensing modalities allow an automobile to recognize the current state of the environment and also be aware of its history.
This is due to the principles developed by Dr.
Joseph Motola, chief technologist in the
ENSCO Aerospace Sciences and Engineering Division.
This sensing ability can be as simple as awareness of road conditions, such as the location of potholes, or as detailed as the types of accidents and how they occurred in a certain area over time.
At the time these cognitive concepts were developed, the level of sensing, processing, memory capacity, and connectivity made them seem far-fetched, but much has changed.
Now, this historical data can be accessed and factored into real-time data from the vehicle’s sensors to provide increasingly accurate degrees of preventive action and incident avoidance.
For example, an IMU can detect a sudden bump or swerve indicating a pothole or an obstacle.
In the past, there was nowhere to go with this information, but real-time connectivity now allows this data to be sent to a central database and used to warn other vehicles of the hole or obstacle.
The same is true for the camera, radar, lidar, and other sensor data.
This data is compiled, analyzed, and fused so that it can inform the vehicle’s forward-looking comprehension of the environment in which it operates.
This allows the vehicle to act as a learning machine that will potentially
make better, safer decisions than a human can.
Multifaceted Decision Making and Analysis
Much progress has been made in advancing state-of-the-art vehicle perception.
The emphasis is on gathering the data from the various sensors and applying sensor fusion strategies to maximize their complementary strengths, and support their respective weaknesses, under various conditions (Figure 5).
Still, much has yet to be done if they are to be truly viable solutions for the problems the industry faces.
For example, cameras can calculate lateral velocity (that is, the speed of an object traveling orthogonally to the direction of travel of the vehicle).
Still, even the best machine learning algorithms require ~300 ms to make a lateral movement detection with sufficiently low false alarm rates.
For a pedestrian moving in front of a vehicle moving at 60 mph, milliseconds can make the difference between superficial and life-threatening injuries, so response time is critical.
The 300 ms delay is due to the time required to perform delta vector calculations from successive video frames.
Ten or more successive frames are required for reliable detection: we must get this down to one or two successive frames to give the vehicle time to respond.
Radar has the capability to achieve this.
Similarly, radar has many advantages for speed and object detection, such as high resolution in both azimuth and elevation, as well as the ability to “seeᾠaround objects, but it too needs to provide more time for the vehicle to react.
With a goal of 400 km/hour or greater unambiguous velocity determination, new developments in 77 GHz to 79 GHz operation are making headway.
This level of velocity determination may seem extreme but is necessary to support complex divided highway use cases where vehicles are traveling in opposite directions at speeds in excess of 200 km/hour.
Bridging cameras and radar is lidar, the characteristics of which have made it a viable and essential element of the fully cognitive vehicle (Figure 6).
But it too has challenges that need to be overcome going forward.
Lidar is evolving into compact, cost-effective solid-state designs that can be placed at multiple points around the vehicle to support full 360 cover- age.
It complements radar and camera systems, adding higher angular resolution and depth perception to provide a more accurate 3D map of the environment.
However, its operation at near-infrared (IR)(850 nm to 940 nm)can be harmful to the retina so its energy output is tightly regulated to 200 nJ per pulse at 905 nm.
However, by migrating to shortwave IR, at over 1500 nm, the light is absorbed over the entire surface of the eye.
This allows more relaxed regulatory requirements of 8 mJ per pulse.
At 40,000 times the energy level of 905 nm lidar, 1500 nm pulsed lidar systems provide 4× longer range.
Also, 1500 nm systems can be more robust against certain environmental conditions, such as haze, dust, and fine aerosols.
The challenge with 1500 nm lidar is system cost, which is largely driven by the photodetector technology (which today is based on InGaAs technology).
Getting to a high-quality solution—with high sensitivity, low dark current, and low capacitance—is the key enabler for the 1500 nm lidar.
Additionally, as lidar systems progress into generation 2 and 3, application-optimized circuit integration will be needed to drive size, power, and overall system costs down.
Beyond ultrasound, cameras, radar, and lidar, there are other sensing modalities that have critical roles to play in enabling fully cognitive autonomous transportation.
GPS lets a vehicle know where it is at all times.
That said, there are places where GPS signals are not available, such as in tunnels and among high rise buildings.
This is where inertial measurement units can play a critical role.
Though often overlooked, IMUs depend upon gravity, which is constant, regardless of environmental conditions.
As such, they are very useful for dead reckoning.
In the temporary absence of a GPS signal, dead reckoning uses data from sources such as the speedometer and IMUs to detect distance and direction traveled and overlays this data onto high definition maps.
This keeps a cognitive vehicle on the right trajectory until a GPS signal can be recovered.
High-Quality Data Saves Time and Lives
As important as these sensing modalities may be, none of these critical sensor inputs matter if the sensors themselves are not reliable and if their output signals are not captured accurately to be fed upstream as high precision sensor data: the phrase “garbage in, garbage out,ᾠhas rarely held so much import.
To achieve this, even the most advanced analog signal chains must be continuously improved to detect, acquire, and digitize sensor signal outputs so that their accuracy and precision do not drift with time and temperature.
With the right components and design best practices, the effects of notoriously difficult issues such as bias drift with temperature, phase noise, interference, and other instability-causing phenomena can be greatly mitigated.
High precision/high-quality data is fundamental to the ability of machine learning and AI processors to be properly trained and to make the right decisions when putting into operation.
And there are few second chances.
Once the data’s quality is assured, the various sensor fusion approaches and AI algorithms can respond optimally toward a positive outcome.
It’s simply a fact that no matter how well an AI algorithm is trained, once the model is compiled and deployed on devices at the network edge, they are completely dependent upon reliable, high precision sensor data for their efficacy.
This interplay between the sensor modalities, sensor fusion, signal processing, and AI has profound effects upon both the advancement of smart, cognitive, autonomous vehicles and the confidence with which we can ensure the safety of drivers, passengers, and pedestrians.
However, all is moot without highly reliable, accurate, high precision sensor information, which is so foundational to safe autonomous vehicles.
As with any advanced technology, the more we work on this, the more complex use cases are identified that need to be addressed.
This complexity will continue to confound existing technology, so we need to look forward to next-generation sensors and sensor fusion algorithms to address these issues.
Like the original moonshot, there is an aspiration that the entire initiative of autonomous vehicles will have a transformative and long-lasting impact on society.
Moving from driver assistance to driver replacement will not only improve the safety of transportation dramatically, but it will also lead to huge productivity increases.
This future all rests on the sensor foundation upon which everything else is built.
Analog Devices has been involved in automotive safety and ADAS for the past 25 years.
Now ADI is laying the groundwork for an autonomous tomorrow.
Organized around centers of excellence in inertial navigation and monitoring and high-performance radar and lidar, Analog Devices offers high-performance sensor and signal/power chain solutions that will not only dramatically improve the performance of these systems but also reduce the total cost of ownership of the entire platform—accelerating our pace into tomorrow.
tutorial/solar-radiation-measurement-methods-using-pyrheliometer-and-pyranometer
Solar Radiation Measurement Methods using Pyrheliometer and Pyranometer
Some of the radiation is beneficial to humans while another radiation is harmful to all life.
To reach solar radiation to the earth's surface it must pass through the atmosphere where it gets absorbed, scattered, reflected, and transmitted which results in the reduction of the energy flux density.
This reduction is very significant as more than 30% loss occurs on a sunny day and on a cloudy day it goes a high as 90%.
So the maximum radiation which reaches the earth's surface through the atmosphere will never be higher than 80%.
Beam Radiation and Diffuse Radiation
that are used to measure beam radiation and diffuse radiation.
Now let us have a look at the spectrum of electromagnetic radiation in the below diagram.
In the entire spectrum, we only consider wavelengths from UV rays to IR rays to calculate the solar flux, because most of the high-frequency waves from the sun do not reach the surface and the low-frequency radiation after IR are not reliable.
So the solar radiation or flux is usually measured form UV rays to IR rays and the instruments are also designed like that.
are of two types:
Pyrheliometer
Pyranometer
Before going into the working of these instruments you need to understand a couple of concepts that are used while designing the devices.
So now let’s look into those concepts.
Black body radiation
reflects all the radiation that falls on it back to the atmosphere that is why we will feel more comfortable wearing white clothes during summer.
Thermocouple
The thermocouple is a simple device constructed using two conductors made of different material as shown in the figure.
at the junctions, so higher temperature differences result in a higher magnitude of the current.
So by getting the reading of ammeter, we can calculate the temperature difference at the junctions.
Now after basics are covered, let’s look into the construction and working of solar radiation measuring instruments.
Pyrheliometer Working and Construction
and its construction.
To understand the basic structure of the Pyrheliometer, look at the diagram shown below.
Here the lens is pointed towards the sun and the radiation will pass through the lens, tube and at the end falls on to the black object present at the bottom.
Now if we redraw the entire internal structure and circuit in a simpler manner it will look something like below.
Deviation ↠Current in loop ↼/strong> Temperature difference at junctions.
Now we will try to nullify this deviation in the galvanometer with the help of the circuit.
The complete process for nullifying the deviation is explained in step by step below.
First, close the switch in the circuit for starting the current flow.
The current flows like,
Battery -> Switch -> Metal conductor -> Ammeter -> Variable resistor -> Battery.
With this current flowing through the Metal conductor its temperature rises to a certain degree.
Being in contact with the Metal conductor the junction ‘Bᾠtemperature also rises.
This reduces the temperature difference between the junction ‘Aᾠand junction ‘Bᾮ
Because of the reduction in temperature difference, the current flow in the thermocouple also decreases.
Since the deviation is proportional to current the deviation of the galvanometer also decreases.
In summary, we can say- The deviation in the galvanometer can be reduced by adjusting the rheostat to change the current in the Metal conductor.
Now keep adjusting the rheostat until the galvanometer deviation becomes completely void.
Once this happens we can obtain voltage and current readings from the meters and do a simple calculation to determine the heat absorbed by the black body.
This calculated value can be used to determine the radiation, as heat generated by the black body is directly proportional to the radiation.
This radiation value is none another than direct beam solar radiation which we are desired to measure from the beginning.
And with this, we can conclude the working of the Pyrheliometer.
Pyranometer Working and Construction
The device looks like a UFO saucer which is the best shape suited for its purpose.
This device is more popular than the others and most of the solar resource data nowadays measured using it.
You can see the original picture and internal structure of the Pyranometer below.
Here the radiation from the surrounding atmosphere passes through the glass dome and falls onto the blackbody situated at the center of the instrument.
Like before, the temperature of the body rises after absorbing all the radiation and this rise will also be experienced by the Thermocouple chain or Thermocouple module present directly beneath the blackbody.
So the one side of the module will be hot and another will be cold because of the heat sink.
The thermocouple module generates a voltage and this can be seen at the output terminals.
This voltage received at the output terminals is directly proportional to temperature difference according to the principle of a thermocouple.
Since we know that the temperature difference is related to radiation absorbed by the black body, we can say the output voltage is linearly proportional to the radiation.
tutorial/three-phase-inverter-circuit-diagram-120-degree-and-180-degree-conduction-mode
Three Phase Inverter Circuit - 120 Degree and 180 Degree Conduction Mode
neglecting all the issues related to practical 3 phase inverter.
3 Phase Inverter Working
and its ideal simplified form.
(for voltage spike protection)
than the cumbersome thyristor circuit.
What we will do here is open & symmetrically closes these six switches to get the three-phase voltage output for the resistive load.
There are two possible ways for triggering the switches to achieve the desired result, one in which switches conduct for 180o and another in which switches only conduct for 120o.
Let us discuss each pattern below:
A) Three Phase Inverter- 180 Degree Conduction Mode
consists of switching pair S5&S6.
At any given time both the switches in the same segment should never be closed as it leads to battery short circuits failing the entire setup, so this scenario should be avoided at all times.
and it will be open only after 300o.
Once the switch is closed it will be kept closed for coming 180o before being opened, with that the S5 will be closed from 240o to 60o (second cycle).
Up until now, all we did was assume that’s the conduction is done once the top layer switches are closed but for current flow from the circuit must be completed.
Also, do remember that both switches in the same segment should never be in the closed at the same time, so if one switch is closed then another must be open.
So only after S1 gets opened we will have to close S2.
Similarly, S4 will be closed after S3 gets opened at 300o and in the same way S6 will be closed after S5 completes the conduction cycle.
This cycle of switching between switches of the same segment can be seen below figure.
Here S2 followsS1, S4 follows S3 and S6 follows S5.
By following this symmetrical switching we can achieve the desired three-phase voltage represented in the graph.
If we fill in the beginning switching sequence in the above table we will have a complete switching pattern for 180o conduction mode as below.
From the above table we can understand that:
From 0-60: S1, S4 & S5 are closed and the remaining three switches are opened.
From 60-120: S1, S4 & S6 are closed and the remaining three switches are opened.
From 120-180: S1, S3&S6 are closed and the remaining three switches are opened.
And the sequence of switching goes on like that.
Now let us draw the simplified circuit for each step to better understand the current flow and voltage parameters.
S1, S4&S5 are closed while the remaining three switches are open.
In such a case, the simplified circuit can be as shown below.
So for 0 to 60: Vao = Vco= Vs/3 ; Vbo = -2Vs/3
By using these we can derive the line voltages as:
Vab = Vao – V bo = Vs
Vbc = Vbo – Vco = -Vs
Vca = Vco ᾠVao = 0
S1, S4&S6 are closed while the remaining three switches are open.
In such a case, the simplified circuit can be as shown below.
So for 60 to 120: Vbo = Vco= -Vs/3 ; Vao = 2Vs/3
By using these we can derive the line voltages as:
Vab = Vao – Vbo = Vs
Vbc = Vbo – Vco = 0
Vca = Vco ᾠVao = -Vs
S1, S3&S6 are closed while the remaining three switches are open.
In such a case, the simplified circuit can be drawn as below.
So for 120 to 180: Vao = Vbo= Vs/3 ; Vco = -2Vs/3
By using these we can derive the line voltages as:
Vab = Vao – V bo = 0
Vbc = Vbo – Vco = Vs
Vca = Vco ᾠVao = -Vs
Similarly, we can derive the phase voltages and line voltages for the next steps in the sequence.
And it can be shown as the figure given below:
A) Three Phase Inverter- 120 Degree Conduction Mode
The 120o mode is similar to 180o at all aspects except the closing time of each switch is reduced to 120, which were 180 before.
As usual, let’s start switching sequence by closing the switch S1 in the first segment and be the start number to 0o.
Since the selected time of conduction is 120o the switch S1 will be opened after 120o, so the S1 was closed from 0o to 120o.
Since half cycle of the sinusoidal signal goes from 0 to 180o, for the remaining time S1 will be open and is represented by the gray area above.
Now after 120o of the first phase, the second phase will also have a positive cycle as mentioned before, so switch S3 will be closed after S1.
This S3 will also be kept closed for another 120o.
So S3 will be closed from 120o to 240o.
Similarly, the third phase also has a positive cycle after 120o of the second phase positive cycle so the switch S5 will be closed after 120o of S3 closing.
Once the switch is closed, it will be kept closed for coming 120o before being opened and with that, the switch S5 will be closed from 240o to 360o
This cycle of symmetrical switching will be continued for achieving the desired three-phase voltage.
If we fill in the beginning and ending switching sequence in the above table we will have a complete switching pattern for 120o conduction mode as below.
From the above table we can understand that:
S1&S4 are closed while remaining switches are opened.
S1 &S6 are closed while remaining switches are opened.
S3&S6 is closed while remaining switches are opened.
S2&S3 are closed while remaining switches are opened
S2&S5 are closed while remaining switches are opened
S4&S5 are closed while remaining switches are opened
And this sequence of steps goes on like that.
Now let us draw the simplified circuit for each step to better understand the current flow and voltage parameters of the 3 Phase Inverter circuit.
S1, S4 are closed while the remaining four switches are open.
In such a case, the simplified circuit can be shown as below.
So for 0 to 60: Vao = Vs/2, Vco= 0 ; Vbo = -Vs/2
By using these we can derive the line voltages as:
Vab = Vao – V bo = Vs
Vbc = Vbo – Vco = -Vs/2
Vca = Vco ᾠVao = -Vs/2
S1 &S6 are closed while the remaining switches are open.
In such a case, the simplified circuit can be shown as below.
So for 60 to 120: Vbo =0, Vco= -Vs/2 & Vao = Vs/2
By using these we can derive the line voltages as:
Vab = Vao – Vbo = Vs/2
Vbc = Vbo – Vco = Vs/2
Vca = Vco ᾠVao = -Vs
S3&S6 are closed while the remaining switches are open.
In such a case, the simplified circuit can be shown as below.
So for 120 to 180: Vao =0, Vbo= Vs/2 & Vco = -Vs/2
By using these we can derive the line voltages as:
Vab = Vao – V bo = -Vs/2
Vbc = Vbo – Vco = Vs
Vca = Vco ᾠVao = -Vs/2
Similarly, we can derive the phase voltages and line voltages for the next upcoming steps.
And if we draw a graph for all the steps then we will get something like below.
It can be seen in the output graphs of both 180o and 120o switching cases that we have achieved an alternating three-phase voltage at the three output terminals.
Although the output waveform is not a pure sine wave, it did resemble the three-phase voltage waveform.
This is a simple ideal circuit and approximated waveform for understanding 3 phase inverter working.
You can design a working model based on this theory using thyristors, switching, control, and protection circuitry.
article/how-close-are-we-to-autonomous-vehicles
How close are we to fully Autonomous Vehicles?
As most of the types of equipment we use today are being automated with state-of-the-art technologies, the advent of autonomous vehicles is no longer a surprise.
Various mechanical features in conventional cars are being transformed into an automatic function.
Consequently, today, semi-autonomous cars have become more ubiquitous than ever.
With technology taking over a great deal of driversᾠjobs in modern vehicles rapidly, the world full of fully autonomous does not seem like an exaggerated version of a child’s dream anymore.
Both interest and investments in fully autonomous cars are increasing significantly, and this is poised to transform the transportation industry very soon.
where cars can be safely driven without any human interference?
Future of Driverless Cars
Driverless cars are set to spread as a life-changing trend in the automotive industry, but what does the arrival of driverless vehicles mean for the world’s transportation system?
autonomous cars are completely self-driving vehicles and can handle any kind of road situation without the need for manual control.
, connected and autonomous cars are will be driving themselves intelligently without any human interference.
A high level of autonomy will give self-driving cars the complete control of the vehicles including speed controls, navigation, emergency features, and many other safety protocols.
How safe are Autonomous Cars?
As the safety of passengers will continue to remain of paramount importance, future road networks can be easily compared to the complexity of blood vessels in the human body.
An infrastructure with efficient traffic management, pollution control, and navigation with the highest safety will take the center stage in the transportation landscape of the future.
The world today seems far away from an infrastructure for fully autonomous vehicles to run on roads, ensuring the safe, effective, and efficient flow of information.
Where does the Automotive World Stand Right Now?
Currently, no self-driving vehicles with autonomy levels 4 and 5 exist in the commercial market.
Autonomous features of modern cars today, include automatic parking, collision detection, and other automatic navigation features advanced driver assistance systems (ADAS).
However, they lack the intelligence required for driving distances automatically and safely, without any human interference.
offer self-driving modes for a pre-defined set of driving functions, commonly in geo-fenced areas.
Audi A8 and Tesla’s Autopilot are among the most popular examples of autonomy levels 3 and 2, respectively.
Offering level 3 autonomous driving features such as hands-off control of the vehicle at medium speeds is on the company’s list of future plans.
also announced its plans to establishing its own subsidiary to boost the development of its level 4 autonomous vehicles including self-driving cargo and passenger versions of its minibus, the I.D.
Buzz.
Other global automotive companies in the race towards the future of fully autonomous vehicles include the collaboration between Mercedes and Daimler; Ford Motor Company through its joint venture with Argo AI; General Motors with its subsidiary GM Cruise; the consortium formed by General Motors, Bosch, Toyota, and Arm; and Google with its Waymo spinoff.
When will we have Fully Autonomous Cars?
, and other communication technologies have fueled the movement in fully autonomous vehicle testing landscape.
However, the reality of autonomous driving still seems like a concept from the future.
We are still away from a technologically strong infrastructure for level 5, fully autonomous vehicles that can completely ‘understandᾠthe complexity of road traffic management and detect several operational issues.
The incompetence of the state-of-the-art software integrated with today’s autonomous cars in taking the ultimate responsibility of safe and efficient driving is creating hurdles in making fully autonomous vehicles readily.
Also, uncertainties about payback and the changing needs for cast-iron is further adding to the high cost of level 4 and 5 self-driving cars.
Nevertheless, technological advancements have bolstered the transition from human-driven cars to fully-autonomous vehicles, notwithstanding the lack of clarity about regulatory and legal frameworks about driverless vehicles.
, the automotive industry is leveraging advancements in cellular network technologies such as 5G with breakneck speeds.
In the coming years, the convergence of the automotive industry with the IT and telecom industry is expected to fuel innovations to improve the safety and efficiency of the AI systems in fully autonomous vehicles, soon turning the future into reality.
tutorial/inrush-current-causes-effects-protection-circuits-and-design-techniques
Inrush Current ᾠCauses, Effects, Protection Circuits and Design Techniques
in their design, we have already covered a lot of popular protection circuits namely
Over Voltage ProtectionOver Current ProtectionReverse Polarity ProtectionShot-circuit Protection
, to protect your Power supply designs from inrush currents.
We will first understand what inrush current is and the reason why it is generated.
Then we will discuss the different types of circuit design that can be used to protect inrush current and finally conclude with some tips to protect your device against inrush current.
So, let’s get started.
What is Inrush Current?
is more used than its DC counterpart.
Each and every circuit draws current from a source depending on the state of the circuit.
Let’s assume a circuit that has three states, that is idle state, normal working state, and maximum working state.
In idle state consider, the circuit draws 1mA of current, in a normal working state the circuit draws 500mA of current and in the maximum working state it can draw 1000mA or 1A of current.
Therefore, if the circuit mostly works in a normal state, we can say that 500mA is the steady-state current for the circuit, whereas 1A is the peak current drawn by the circuit.
Now, why this high current is suddenly drawn by the circuit as it is rated for low current application? Such as the previous example, 1mA to the 1000mA.
What causes Inrush Current in a device?
to develop the magnetic or electric field required for their operation.
Thus the input of the circuit suddenly provides a low resistance (impedance) path which allows a large value of current to flow into the circuit.
to better understand how it works in a circuit.
to better understand how inductors work in a circuit.
is shown.
The time shown in milliseconds but that can be in microseconds too.
However, during the startup, the current start to increase and the maximum peak current is 6A.
It is the inrush current that exists for a very short time span.
But after the inrush current, the current flow gets stable at a value of .5A or in 500mA.
This is the steady-state current of the circuit.
gets very high to cause the input switch melting or blown-up.
Inrush Current Protection Circuits ᾠTypes
There are many methods to protect your device from inrush current and different components are available to protect the circuit from inrush current.
Here is the list of effective methods to overcome inrush current-
in AC supply input.
gets heated up during normal operation and reduces efficiency.
The resistor wattage depends on the application requirement, typically ranges between 1W to 4W.
circuit is similar to resistor limiting method, Thermistor or NTC (Negative temperature coefficient) is also used in series with the input.
This property is used for the Inrush current limiting application.
During the initial startup of the circuit, the NTC provides high-value resistance which decreases the inrush current flow.
But during the circuit goes into the steady-state condition, the temperature of the NTC starts increasing which further resulted in low resistance.
NTC is a very effective method of controlling inrush current.
Soft Start or Delay circuit
Such type of functionality enables us to change the output rise time which effectively reduces the output current when connected to a high-value capacitive load.
from Texas Instruments offers programmable soft-start pin where the user can configure Linear Start Up using a simple external capacitor.
In the below circuit diagram, an example circuit of TPS742 is shown where the soft-start time is configurable using the SS pin by using theCSS capacitor.
Where and why we need to consider Inrush Current Protection Circuit?
is required.
The inrush current circuit stabilizes the high current requirement in the initial starting stage of the circuit.
An inrush current limiter circuit limits the input current and keeps the source and the host device safer.
Because a high inrush current increases the failure chances of the circuit and that needs to be rejected.
Inrush current is harmful because of the following reasons-
High inrush current affects the source power supply.
Often high inrush current drops the source voltage and results in a brownout reset for microcontroller-based circuitry.
In few cases the amount of current supplied to the circuit gets beyond the acceptable maximum voltage of the load circuit, causing permanent damage to the load.
In high voltage AC motors, the high inrush current causes the power switch to trip or sometimes burned out.
The PCB board traces are made to carry a specific value of current.
The high current could potentially weaken the PCB board traces.
Therefore, to minimize the effect of inrush current, it is important to provide an inrush current limiter circuit where the input capacitance is very high or has a large inductance.
How to measure Inrush Current:
is the fast time span.
Inrush current occurs for a few milliseconds (or even microseconds) depending on the load capacitance.
The value of the time span generally differs from 20-100 milliseconds.
which has the option to measure the inrush current.
The meter gets triggered by the high current and takes multiple samples to get the maximum inrush current.
but this process is a bit tricky.
One needs to use a very low-value shunt resistor and requires two channels to connect across the shunt resistor.
By using the different functions of these two probes one can get the maximum peak current.
One needs to be careful while connecting the GND probe, the wrong connection across the resistor could lead to a short circuit.
The GND needs to be connected across the circuit GND.
The below image is the representation of the above-mentioned technique.
Factors to consider while designing an Inrush Current Protection Circuit:
Here is a list of few essential parameters ᾍ
The capacitance of the load is essential parameters to select the specification of inrush current limiting circuit.
High capacitance requires a high transient current during startup.
For such a case an effective soft start circuit is required.
can be a choice.
How fast the load gets on or off during a given time frame is another parameter to choose the inrush current limiting method.
For example, if the switching on/off time is very fast then the NTC could not protect the circuit from inrush current.
Because, after a first cycle reset, the NTC does not get cooled down if the load circuit is turned off and on in a very short time span.
therefore the initial start resistance couldn’t be increased and the inrush current gets bypassed through the NTC.
In specific cases, during circuit design, if the power source and the load is existing inside the same circuit it is wiser to use voltage regulator or LDOs with soft start facility to reduce the inrush current.
In such a case, the application is a low voltage low current application.
tutorial/biasing-methods-of-class-a-bjt-amplifiers
Biasing Methods of Class A BJT Amplifiers
for linear audio frequency class A amplifier operation, linear meaning the output signal is the same as the input one but amplified.
The Basics
For a regular silicon transistor to work in the active mode (used in most amplifier circuits) it’s base has to be connected to a voltage at least 0.7V (for silicon devices) higher than the emitter.
After applying this voltage the transistor turns on and collector current starts flowing, with a drop of 0.2V to 0.5V between the collector and emitter.
In the active mode, the collector current is roughly equal to the base current times the current gain (hfe, β) of a transistor.
Ib = Ic/hfe
Ic = Ib*hfe
here.
Fixed Bias
The simplest way to bias a BJT is presented in below figure, R1 provides the base bias and output is taken between R2 and the collector through a DC blocking capacitor, while the input is fed to the base through a DC blocking capacitor.
This configuration should only be used in simple preamplifiers and never power output stages, especially with a speaker instead of R2.
To bias the transistor we need to know the supply voltage (Ucc), the base-emitter voltage (Ube, 0.7V for silicon, 0.3 for germanium transistors), the required base current (Ib) or the collector current (Ic) and the current gain of the transistor (hfe, β).
R1 = (Ucc - Ube)/Ib
R1 = (Ucc - Ube)/(Ic/hfe)
It is recommended for the load impedance or the input impedance of the next stage to be at least 4 times greater than R2.
The coupling capacitors should provide less than 1/8 the load impedance or the input impedance of the following stage at the lowest frequency of operation.
Voltage Divider Bias / Self Bias
The below figure is the most widely used biasing configuration, it is temperature stable and provides very good gain and linearity.
In RF amplifiers R3 can be replaced with an RF choke.
In addition to a single base resistor (R1) and collector resistor (R3), we have an additional base resistor (R2) and an emitter resistor (R4).
R1 and R2 form a voltage divider and along with the voltage drop on R4 set to the base voltage (Ub) of the circuit.
The calculations are more complicated, due to there being more components and variables to account for.
First we start with calculating the resistor ratio of the base voltage divider, dictated by the formula shown below.
To start the calculations we need to estimate the values of the collector current and resistors R2 & R4.
Resistor R4 can be calculated to drop 0.5V to 2V at the desired collector current and R2 is set to be 10 to 20 times greater than R4.
For preamplifiers R4 is usually in the range of 1k-2k ohm.
The non-decoupled R4 causes negative feedback, decreasing gain while decreasing distortion and improving linearity.
Decoupling it with a capacitor increases gain so it is recommended to use a large value capacitor with a small resistor in series.
case-studies/best-practices-to-change-the-direction-of-lt-motors-to-avoid-industrial-accidents
The best practice to change the direction of LT Motors to avoid Industry Accidents
that are below 15 KWs,the phase sequence inside the panel (the terminals below the power contactor or below thermal overload relay) is normally changed as shown in the picture above.
situation, which may not only damage the motor but case a server accident with life-threatening situations.
This happens normally in process industries, where there are many identical motors with the same rating.
These motors are used for similar applications and there are powered by the same MCC.
Also, there can be similar motors for different applications in the same MCC.
in all the feeders will be R, Y & B only (From Left to right).
During O&M or plant shutdown, many times it might occur that due to plant requirements or due to some problem in the equipment we must change the direction of motors.
In order to do this in an easy way, the engineer or technicians change the direction of the motor by changing the power cable sequence below the relay or power contactor.
Also at times, when we are replacing the motor with a new motor and while taking a no-load trial, we found that the direction of the new motor is reversed, so we interchange the R & Y power cable below Relay or Power contactor as it is less hectic and take less time.
Now our motor is running in the correct direction but inside the feeder cable is Y, R and B combination.
Now that rotation in the wrong direction can be hazardous or non-hazardous.
It may increase the downtime, or it may damage a few components of equipment, or it may cause near-miss to the field personnel or it may cause a serious accident.
Ultimately something will be lost.
Hence, we always recommend while changing the direction of Motor (For below 15 kW) from a feeder, we must do it from the panel termination side as marked in Photo.
We know it will take more time but not more than 5-6 minutes than changing the direction of the cable below relay or contactor.
I am sharing this case study so that there is no Incident like this happening in any plant.
You too share this article so that Technicians and Field engineers can note this point and watch out for it and yes we would like to have your comments and suggestions on such cases.
About the Author
is an Electrical Engineer with over 11 years of rich experience in Electrical Maintenance, Installation, Testing, and Commissioning of all major Electrical equipments.
He is specialized in bringing down Energy Cost of a Plant by reducing electricity bills and increasing energy efficiency.
He also reduces plant breakdown cost by implementing proper maintenance activities during routine and shutdown.
Through these Case Studies he shares his experience and challenges faced in his work routine with the readers of Circuit Digest.
article/what-is-ai-should-we-fear-advances-in-artificial-intelligence
What is AI? Should Humanity Fear Advances in Artificial Intelligence?
is one of the greatest discoveries in the field of science, and it has begun to become more prevalent than everworldwide.
Scientistsᾠcuriosity about how more can be done with this technology is showing no signs to recede.
Is it time, already, to get frightened of the potential of Artificial Intelligence to become smarter than us? Artificial intelligence will destroy humanity?
Automobiles with petrol or gasoline-powered internal combustion engines were invented back in the 1880s, as the need for efficient and convenient commutation was felt.
But today, they are among the most prominent factors causing air pollution and posing harm to the environment.
as a device programmed to carry out critical and tedious operations.
Today, we discuss among each other how using computers has compromised humansᾠmultitasking skills as well as physical health.
as the computer networking revolution began and scientists needed to solve the problem of long-distant communication among themselves.
Though it was one of the most brilliant inventions, today, the internet has become the very factor that is powering the severity of cyber threats and cyber-attacks.
century.
The father of AI ᾠJohn McCarthy deciphers AI as a technology for creating a highly-intelligent device or machine that can reach the level of intelligence to perform all the tasks that currently only humans can do.
With time, most of the scientific discoveries reflected technologies more and more intelligent than their prior counterparts.
Today, the adoption of this technology of AI has begun to grow incessantly (?) not only in the industrial sector—with the rise of the Industry 4.0 trend—but it is also emerging in consumersᾠlives integrated into commonly used consumer electronics.
As we have entered the century of smart appliances and AI-driven robotic machines which are more intelligent than ever, has the time come to imagine how dire the consequences might be of this potentially dreadful, super-intelligent technology? As says Tesla’s Elon Musk—who is normally anything but a technology pessimist—is AI really more dangerous than nuclear warheads and the “biggest existential threatᾠto humanity?
What exactly is AI?
The science of AI can be simply translated as the science of making machines and appliances smart enough to give them the ability to perform all the tasks that humans do.
Typically, there are three stages of intelligence in AI ᾠNarrow AI, General AI, and Super AI.
normally deals with developing and programming machines to carry out just one specific task.
The most commonly known example of narrow AI is self-driving cars; though it has multiple narrow AI systems operating in the background.
goes one step ahead of narrow AIit develops machines that can perform tasks, like solving problems, as efficiently as humans, or in some cases, even better than humans could ever do.
which is also referred to as superintelligence, is everything we should fear about AI.
It can give machines the ability to make decisions, think like humans, to be creative, even give them social skills, which could be the power to take over humanity one day.
that can solve problems or create a big one?
How Artificial Intelligence can be menacing if not Realised its Severity Soon
Many scientists think that a super AI is unlikely to program machines to imitate human emotions like love, hate, revenge, or empathy.
We are much behind the time when AI would intentionally become malevolent or vengeful.
Yet, what could possibly happen if scientists and engineers could ever create machines with superintelligence?
is most likely to eat up jobs of humans in various fields of industries.
These speculations are often criticized with arguments about the new jobs that AI-driven automation will create.
However, the fact that it will only create jobs for humans with a particular skill set is real, and ultimately it will result in the loss of many jobs.
Secondly, it would only be foolish to overlook the dystopian possibilities of AI contributing to the creating of autonomous weapons that could be used in wars.
AI gives the power to create arms and missiles in such a way that it will be extremely difficult to turn them off in critical situations.
In worst-case scenarios, humans could utterly lose control over these ‘intelligentᾠweaponryand it could result in a devastating future of mass casualties.
The Verdict: Is it Time to be frightened of the Rise of AI?
Scientists and engineers who are actually working on developing this technology are more worried about understanding whether there are certain kinds of behavior or other issues that need to be fixed with AI.
While considering the various ways in which technology can be improved, it is extremely difficult to implement all the plans in the imagination.
Many of the scientists believe that thinking about the potential of AI harming humans reflects that we are overestimating the power of this technology.
ᾍ
Though creating a machine with its decision-making capabilities and human emotions sounds like a distant alarm right now, with all the efforts and energy we are putting to find out whether that is possible, we could certainly be heading towards self-destruction!
tutorial/an-introduction-to-grid-dip-meter
A Basic Introduction to Grid Dip Meter
is an electronic instrument used in measurement and testing of radio frequency circuits.
It is basically an oscillator with an exposed coil and oscillation amplitude readout.
It has three main functions:
Measuring the resonant frequency
of an LC resonant circuit,
a Crystal/Ceramic resonator,
or an Antenna,
Measuring inductance or capacitance,
Measuring the frequency of a signal,
Generation of RF sine wave signals.
here.
What’s behind the name?
and used to measure the oscillator amplitude by measuring the current flowing through the grid resistor.
(Trans dip oscillator/meter).
They can also be made with a tunnel diode (tunnel dip oscillator/meter) instead of a transistor or tube.
The Basic Circuit
ᾠby Andrzej Janeczek, call sign SP5AHT.
It is quite possibly the simplest GDM circuit using a BJT,
that rectifies (magnetic meters can’t measure AC) the signal, which is then filtered by C1 and fed to the 50uA meter via the sensitivity setting pot P1.
with hFE of over 150 and transition frequency of over 100MHz, such as 2SC1815, 2N2222A, 2N3904, BF199.
L depends on the desired band, for LW and MW it can be wound on a ferrite rod but at SW and up air core is better.
For 3MHz ᾠ8MHz band it’s 11uH but can be calculated using the many coil calculators online for different bands
Measuring Resonance of an LC Circuit
The use of a Grid Dip Meter as an inductor-capacitor resonant circuit resonance measuring device depends on the circuit.
If it is just a resonant circuit, not connected to anything and with the coil exposed, you just need to put the coil of the resonant circuit close to the exposed coil of the GDM, tune your GDM until the meter drops.
This drop is caused by the resonant circuit coupled to the coil in the GDM absorbing some of the energy in the resonant circuit, causing a drop in the oscillator’s output voltage and a change in the meter’s displayed value.
If the coil is shielded (IF transformers for example) you need to couple the GDM by winding a few turns of wire and connecting it between
Measuring Resonance of a Resonator
when the label has worn off.
All you need to do is connect a few turns of wire around the GDM coil and connecting that loop to the crystal.
The resonance will be very steep so you need to tune the GDM very slowly.
Measuring Antenna Resonance
To measure the resonance frequencies of an antenna (such as a dipole) wind a few turns of wire around the GDM coil and connect it to the antenna connector.
Tune the GDM and exchange coils until you see the dip on the meter.
You can also measure how wideband is the antenna is by noting how fast the needle drops during tuning.
Measuring Inductance or Capacitance
by making a resonant circuit with the measured inductor or capacitor and a known value capacitor/inductor in parallel and tuning the GDM and changing coils until you see the dip on the meter, just like with a regular LC circuit.
Input the resonance frequency and the known capacitance/inductance into an LC resonance calculator to get the unknown inductance/capacitance.
to measure the capacitance and the frequency.
Measuring the Frequency of a Signal
There is two way of measuring the frequency using the GDM:
Absorptive frequency measurement
Heterodyne frequency measurement
works when the GDM is turned off, the signal is applied to a few turns of wire looped around the GDM coil, then the meter is tuned and the coils are changed until the meter readout goes up and that is the signal frequency.
The absorptive frequency measurement mode works similarly to a crystal radio, the GDM tuned circuit rejects all signals from frequencies other than it’s resonant frequency, the diode turns the high-frequency AC of the signal to DC because meters can only work with DC.
It only works with those GDM types that have the meter connected to the resonant circuit via a diode, such as the one in the Basic TDO circuit explained earlier.
The signal amplitude has to be relatively high, no less than 100mV, because of the forward voltage of the diode.
It can be also used to see the level of harmonic distortion in the signal, simply tune the GDM to a frequency 2, 3 or 4 times higher than the measured signal frequency and also tune to a frequency 2 or 3 times lower to see if you didn’t measure a harmonic in the first place.
mode only works with those GDM that have a dedicated phone jack.
It works on the principle of mixing frequencies, for example, if our GDM oscillates at 1000kHz and there is a 1001kHz signal coupled to the GDM coil the frequencies heterodyne (mix) creating a signal on 1kHz (1001kHz ᾠ1000kHz = 1kHz) which can be heard if there are headphones plugged into the jack.
This is a much more sensitive and accurate method of frequency measurement and can be used to match crystals for crystal filter.
Signal Generation
To use your GDM as a variable frequency oscillator all you to do is wind a coil over the original GDM coil and connect a buffer amplifier to it.
The use of a buffer amplifier is recommended because taking the output directly from the coil wound over the GDM coil will load it and cause amplitude and frequency instability and maybe even the oscillations dying down.
Generation of modulated RF signals
, 120Hz AC after rectification (first two are the usual methods in old tube GDM) or by having an onboard AF generator (more often found in fancy transistor TDMs).
If the modulation happens at the generator, there might be a small FM component in the AM signal.
case-studies/is-spacing-an-important-factor-to-consider-while-mounting-an-auxilary-contactor
Is spacing an important factor to consider while mounting an Auxiliary Contactor?
related to Electrical Maintenance, hope you are enjoying them and they are useful during your plant operations.
My motto behind sharing my experience is that the problem faced in one plant should not be repeated to other Plant.
That being said.
Let’s get into today’s case studies.
inside your panel as shown in the below picture.All the below contactors are closely packed without any space between them, but is it the right way of putting it together? Sometimes even the Panel manufacturer might say that nothing is wrong, but as a maintenance engineer, what I have noticed is it will be a problem in the long run.
What to know why? Let me explain
just because there is no space between them? Turns out it can and this is how the incident happened in May 2015.
and hence it was not picking up and the feedback signal was not going to control room, ultimately tripping the Motor, we replaced it with spare Auxiliary contractor, that’s what we normally do as a maintenance engineer so that the downtime decreases.
We tried to find out what could have happened but didn’t get it during the first time, all we understood was that the Auxiliary contactor has heated and failed.
compared to other parts of the control cabinet in the HT panel.
And on further analysis, we found that the temperature of 4-5 contactors wason the higher side.
We were getting closer, ourHOD advised to create some space between all the auxiliary contactors in one HT Motor panel and compare the temperature with those with no space in between.
properly because there was no space between Auxiliary contractors, and due to this heat generated by the contactors were accumulated there only due to no space for dissipation and in the long run contactor coil was burning or contactor failing.
We rearranged the contactors in the panel as shown in the below picture and the problem did not seem to come back.
There could be many reasons for temperature difference in panels.
We checked the same with Other HT panels too and yes temperature on contactors in Panel with some spaces between Auxiliary contactors was on the lower side compared to those with no space between Auxiliary Contactor.
The same was implemented across the plant, as per the space available.
Also, every plant has its own space problems in HT panels, but what we as a maintenance engineer found out that keeping a small space between Auxiliary contactor is good in the long run.
You too can try measuring the heat of the auxiliary contractors on your HT panel with and without space and let us know what you observed.
I will be eager to know the results.
About the Author
is an Electrical Engineer with over 11 years of rich experience in Electrical Maintenance, Installation, Testing, and Commissioning of all major Electrical equipments.
He is specialized in bringing down Energy Cost of a Plant by reducing electricity bills and increasing energy efficiency.
He also reduces plant breakdown cost by implementing proper maintenance activities during routine and shutdown.
Through these Case Studies he shares his experience and challenges faced in his work routine with the readers of Circuit Digest.
article/biggest-electric-manufacturers-that-are-tackling-the-climate-change-smartly
Biggest Electric Vehicle Manufacturers that are Tackling Climate Change Smartly
from around the world that are bringing in the noticeable changes in carbon footprints with their electric vehicles.
1. Ford
and Lincoln luxury vehicles.
The company provides financial services through Ford Motor Credit Company and it continues to hold leadership positions in electrification, autonomous vehicles, and mobility solutions for many years.
Today, the company touches the lives of millions in different corners of the globe by manufacturing and selling the hi-tech, reliable, and fun-to-drive vehicles in the world.
For the sustainable future, the company aims to launch 16 electric vehicles and 40 electrified vehicles by 2022.As of now, the company offers the Mondeo Hybrid, new Mondeo Hybrid, and transit custom PHEV.
2. Renault
is a company that has rolled out iconic vehicles and introduced us to the futuristic concepts, since the very inception i.e from 1898.
Well known for automotive Engineering, style, design, manufacturing, and ever-increasing sales, the company has made a mark in the automobile sector.
In 2018, the Renault Group unveiled EZ-GO, EZ-PRO, and EZ-ULTIMO, three robot-vehicle concepts illustrating its vision of urban and shared mobility of the future.
The company proudly boasts of manufacturing 100% electric vehicles on a large scale.
In fact, it is currently leading the row by manufacturing a huge number of electric vehicles in Europe.
The company claims that with vehicles like Renault ZOE, Twizy, Kangoo ZE, and RSM SM3 ZEsedan, the all-new Renault Master ZE, it will have 8 electric vehicles and 12 electrified vehicles in 2022.
3. Honda
is a North American subsidiary of Honda Motor Company, Ltd.
The company was founded in 1959 with its first store opened up in Los Angeles, CA and in last many years the company has been manufacturing products like lawnmowers, tillers, string trimmers, snow blowers, generators, small-displacement general-purpose engines and marine outboard engines that have left customers in awe several times.
The company proudly declared that it has been recognized as the very first international automaker capable of complete product creation in the U.S.
Besides, in 2014, 97% of Honda vehicles sold in America were manufactured here using globally and locally-sourced parts.
Honda Motor Company is aiming to ensure there are Blue Skies for upcoming generations, which is why it is voluntarily working to reduce carbon dioxide emissions by 50% by 2050.
The company launched its first plug-in EV in Europe in 2019.
The company is making every possible effort to reduce its carbon footprint.
Honda strives to electrify two-thirds of global automobile unit sales in 2030.
As zero-emission vehicles (ZEV), Honda has strengthened the development of electric vehicles (battery EV) along with fuel cell vehicles (FCV).
4. Groupe PSA
, automobile manufacturing, innovation, lean manufacturing, etc.
Groupe PSA was the first manufacturer to test its autonomous vehicles on public roads since July 2015 in France.
It is Europe’s second-largest vehicle manufacturer that has brought significant transformation in the automobile industry and is continuing the transformation with a new strategic plan - Push to Pass.
The main aim of this plan is to market vehicles of cutting-edge efficiency and the mobility services acclaimed by its customers.
The Group with five car brands viz.
Peugeot, Citron, DS, Opel, and Vauxhall have been providing unique automotive experiences and delivering the best mobility solutions for the last many years.
The company has been aiming at introducing electrified versions of the existing vehicles and has been successfully featured on the CDP Climate Change A-List.
5. Toyota
is a global automotive manufacturing company that was founded in 1937 and is headquartered in Toyota City, Japan.
Toyota which is the official fleet provider for the 2020 Games and the nation’s flagship car company, announced in August that 90% of the vehicles it provides will be “electrified.ᾍ
ready to be rolled out this year and claims that all the models manufactured by Toyota will have electric versions by 2025.
6. BMW
models.
Besides, the company is also focusing on electrifying additional models.
Thecompany also plans to roll out BMWi4from the Munich plant in 2021.
7. Tesla
boasts of producing high-quality vehicles with innovative technology and cutting-edge features.
To accelerate the world’s transition to sustainable energy, the California-based Tesla offers best-in-class affordable electric vehicles.
Currently, over 275,000 Model S, Model X, and Model 3 vehicles are on the road worldwide.
grids.
8. Geely
Holding Group launched its automotive business in 1997 and is headquartered in Hangzhou, China.
Zhejiang Geely Holding Group (ZGH) is a global automotive group that owns various international automotive brands.
The Group is comprised of five main businesses: Geely Auto Group, Volvo Car Group, and Geely New Energy Commercial Vehicle Group, Geely Technology Group, Mitime Group.
The company rolled out its first electric vehicle, Emgrand EV on 18 November 2015 and it has since gone on limited sale in China to fleet buyers in certain larger cities such as Beijing.
The Emgrand EV is capable of traveling 253km on a single charge and when using rapid speed charging it can be charged to 80% capacity in just 30 minutes on a slow charge.
9. Chevrolet
is one of the leading automotive manufacturers that is dedicated to challenging the limits of what's possible in automotive design and engineering today, tomorrow and for years to come.
Intending to find the new roads and expand the horizon, Chevrolet had rolled out TheChevrolet BoltorChevrolet Bolt EVwhich is a front-engine, five-doorall-electricsubcompacthatchback developed and manufactured in partnership withLG Corporation.
The Bolt has anEPAall-electric rangeof 383km.
10.
Zhidou
Electrical Vehicle Sales is a Chinese manufacturer co-funded by Geely Holding Group, XDY, and GSR Capital.
In 2016, the company won the second prize in the National Technology Invention Award.
Zhidou has introduced the Micro-Traveling concept in the industry, and its core product, ZHIDOU pure electric vehicles has a range of 160km, with a top speed of 80kmph and a 0-45km of eight seconds.
In 2015, the company got the top spot in the ‘top 10 green brands awardsᾮ
or soon plan to do so.
With the majority of companies in automobile industries turning to electric vehicles and planning to make their existing models too electric, we can expect a green and clean future with lesser carbon emissions.
article/electrical-enclosures-10-factors-to-consider-before-selecting-one
Electrical Enclosures - 10 Important Factors to Consider Before Selecting One
, engineers need to take into consideration various factors such as power consumption, heat dissipation, and other electronic specifications, to ensure the appropriate selection of electronic components particularly designed for diverse applications in both, industrial and commercial sectors.
The electronic enclosure is one of the most critical components in electronic circuits, as it does not only house the entire module but also protects it from damages and circuit failures caused due to various environmental factors.
Thereby, it is becoming of utmost importance to select appropriate electronic cabinets or an electronic enclosure according to the project specifications to mitigate the risks of downtime and operational hindrances.
Here are the 10 most important factors to keep in mind for selecting an appropriate electronic cabinet.
1. Engineering Application and IP Ratings
The scope and application of your electrical circuit play an integral role in the selection of electronic enclosure.
The design of electronic cabinets may change according to the electronic specifications of your circuit and its engineering applications.
Furthermore, the requirements about Ingress Protection ratings (IP ratings) also reflect a crucial factor in the selection process as they precisely address the needs vis-à-vis the degree of protection against contact with live parts, damage control against mechanical impact, and other mechanical factors such as the opening of water along with other solid foreign components.
2. Environmental Conditions
It is important to understand what operating environment and weather conditions the circuit will be exposed to, in order to make the appropriate choice of an electronic enclosure.
Having clarity about where the enclosure is going to reside is necessary, especially for choosing the right material.
Based on whether the enclosure will be walled in indoor areas, outdoors, exposed to harsh heat conditions or chemical contaminants or in extreme weather conditions, the material and other specifications of an electronics enclosure can be derived.
3. Thermal Requirements
Thermal conditions and specifications of the electronic circuit must be taken into consideration while choosing cabinets for sensitive electrical components.
This is another important aspect that makes a significant impact on the choice of material for electronic enclosures.
Plastics are excellent insulators, which can be used in enclosures for electronic circuits with low heat dissipation needs.
However, for circuits with high voltage and high current specifications, which may potentially reflect in significantly high power density and heat dissipation, metallic enclosures may prove more suitable.
4. Industry Standards related to Design and Performance
Governing bodies, international standard committees such as International Electro-Technical Commission (IEC) and as well as government policymakers and regulators have defined and developed industry standards for electrical, electronic and related technologies.
These identify specifications of a product that must be conformed with, and they must be taken into consideration while choosing the right electronic enclosure.
5. Types of Materials
Recent advancements in material sciences and technologies have increased the availability of various types of materials to suit the exact need for electronic enclosures in different applications.
Apart from the thermal, electrical, and environmental requirements, other factors that may influence the choice of materials in electronic cabinets are price, size, weight, and aesthetics.
Acrylic is one of the most cost-efficient window materials.
Acrylic is one of the popular choices of materials, as it is lightweight, flexible, lightweight, and mainly due to its greater impact resistance qualities over the glass.
Another material that is gaining popularity is Polycarbonate.
Despite being more expensive than acrylic, its impact and chip resistant properties and thermal stability are reflecting in the rise in its adoption.
Apart from acrylics and polycarbonate, other materials that are commonly used in cabinets include glass, metal, galvanneal, aluminum, copper, and stainless steel, and these must be chosen carefully based on the needs of the application.
casings.
It is easy to build, prototype and modify the design using a 3D printer before finalizing one.
6. Total Cost of Ownership (TCO)
Understanding the value of cabinets, which mainly depends on the purchasing cost along with operating and maintenance costs, is important while making the right choice of electronic enclosures.
An appropriate enclosure can be selected by taking into consideration the maintenance and downtime costs that may incur in different varieties, which ultimately have an impact on the TCO.
7. Size of the Equipment
This is one of the most basic yet important factors that must be thought of while choosing an appropriate enclosure.
Though smaller sizes of enclosures are preferred in modern electronic equipment, the depth of the final product must be considered while choosing a cabinet to make the process of installation more convenient and feasible.
Furthermore, the electronic enclosure should also be big enough to enable proper power distribution and cable management in the circuit.
8. Flexibility of Design
Based on the design of the circuit, the enclosure should offer enough flexibility in terms of depth, height, and width.
Also, with the advent of advanced technologies such as Information Technology (IT), Big Data, and the Internet of Things (IoT), the enclosure should be flexible enough to integrate various controls for routers and other IT equipment.
9. Electromagnetic Compatibility
With the increasing incorporation of advanced technologies and modern electronic appliances becoming faster than ever, the problem of electromagnetic interference (EMI) has become a prominent concern.
With the issue of EMI becoming more prevalent, an enclosure that can offer EMI protection must be chosen in cases where the equipment is used in environments with the presence of EMI.
10.
Scope for Future Modifications
It is probably the most important factor that needs to be considered while making a choice of an electronic enclosure.
Think about the potential for modification and cutouts for various reasons such as for adding a weather control to the roof, creating space for Human-Machine Interface (HMI), or adding a cable entry, when selecting a cabinet for your equipment.
case-studies/does-motor-or-transformer-in-your-plant-burn-out-without-any-warning-signs
Does Motor or Transformers in your plant fail or Burn-out without any warning signs?
has proven to be a highly valuable predictive maintenance tool.
In this case study, I will explain more on MCSA and how we use it during our maintenance schedule.
What is Electrical Signature AnalysisOr Motor Current Signature Analysis?
ESA is remote, non-intrusive and is invisible to the equipment being monitored!
when it is not possible or convenient to make vibration measurements.
When an electric motor drives a mechanical system, it experiences variations in load caused by gears, pulleys, friction, bearings and other conditions that may change over the life of the motor.
The variations in load caused by each of these factors, in turn, cause a variation in the current supplied to the motor.
These variations modulate the carrier frequency.
This testing Equipment utilizes a unique process to demodulate the signal from the carrier and present an unambiguous spectral display.
Using normal and demodulated data permits analysis of not only the motor but also the load and the supplied power.
Rotor bar deterioration
Rotor eccentricity
Stator phase imbalance
Motor speed & slip
Gear & belt imperfections
Average running current, an indicator of motor torque
Stroke time on assemblies with defined start & stop points
Torsional vibration & dynamic loading
Bearing degradation
Changing friction forces
Detects the Early Stages of Rotor Bar Failures in Induction Motors
Saves Time and Precludes Plant breakdowns by Monitoring Plant Motors and Driven machinery from a Central Motor Control Center
Permits Data Acquisition and Analysis from Multiple Sources ᾍ
Accelerometers
Proximity Probes
Process Measurements
AC Induction Motors
DC Motors
Generators & Transformers
About the Author
is an Electrical Engineer with over 11 years of rich experience in Electrical Maintenance, Installation, Testing, and Commissioning of all major Electrical equipments.
He is specialized in bringing down Energy Cost of a Plant by reducing electricity bills and increasing energy efficiency.
He also reduces plant breakdown cost by implementing proper maintenance activities during routine and shutdown.
Through these Case Studies he shares his experience and challenges faced in his work routine with the readers of Circuit Digest.
article/what-is-solid-electrolyte-interface-sei-to-improve-lithium-ion-battery-performance
Understanding Solid Electrolyte Interface (SEI) to Improve Lithium Ion Battery Performance
both the terms are used interchangeably overall research papers and hence it is hard to argue on which is the correct term.
For the sake of this article, we will stick to the solid electrolyte interface.
Lithium-ion batteries:
article to understand EV batteries before you proceed further.
Graphite, carbon black, lithium titanate (LTO), Silicon, and graphene are some of the most preferred anode materials.
Most commonly graphite, coated on copper foil used as the anode.
Graphite’s role is to act as a storage medium for lithium ions.
Reversible intercalation of liberated lithium ions can be easily done in the graphite due to it’s loosely bonded layered structure.
Pure Lithium having one valance electron on its outer shell is highly reactive and unstable, so that stable lithium metal oxide, coated on aluminium foil used as the cathode.
Lithium metal oxides like Lithium nickel manganese cobalt oxide ("NMC", LiNixMnyCozO2), Lithium Nickel Cobalt Aluminium Oxide ("NCA", LiNiCoAlO2), Lithium Manganese Oxide ("LMO", LiMn2O4), Lithium Iron Phosphate ("LFP", LiFePO4), Lithium Cobalt Oxide (LiCoO2, "LCO") are used as cathodes.
Electrolyte between the negative and positive electrodes must be a good ionic conductor and an electronic insulator that means it has to allow the lithium ions and has to block the electrons through it during the charging and discharging process.
an electrolyte is a mixture of organic carbonate solvents such as ethylene carbonate or diethyl carbonate and Li-ion salts such as lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium Hexafluoroarsenate monohydrate (LiAsF6), lithium triflate (LiCF3SO3), and lithium tetrafluoroborate (LiBF4).
Separator is a critical component in the electrolyte.
It acts as an insulating layer between anode and cathode to avoid the short circuit between them while allowing the lithium ions from the cathode to anode and vice versa during charging and discharging.
In lithium-ion batteries mostly polyolefin is used as the separator.
Charging and Discharging Process
During the charging process when we connect a power source across the battery, energized Lithium atom, gives Lithium ions and electrons at the positive electrode.
These Li-ions passes through the electrolyte and gets stored in the negative electrode, while electrons travel through the external circuit.
During the discharge process when we connect external load across the battery, the unstable Li-ions stored in negative electrode travel back to the metal oxide at the positive electrode and electrons circulate through the load.
Here aluminum and copper foils act as current collectors.
SEI formation:
This passivating layer protects the electrode from the corrosion and further consumption of electrolyte, the formation of SEI occurs in two stages.
happens simultaneously with the intercalation of lithium ions on the anode.
The resulting SEI film is porous, compact, heterogeneous, insulating to electrons tunneling and conductive for lithium ions.
Once the SEI layer forms, it resists the electrolyte movement through the passivating layer to the electrode.
So that it controls the further reaction between electrolyte and lithium ions, electrons at the electrode and thus restricts the further SEI growth.
Importance and Effects of SEI
for better performance.
Well adhered SEI on electrodes maintains good cycling ability by preventing further consumption of the electrolyte.
The proper tuning of porosity and thickness of the SEI layer improves the lithium ions conductivity through it, results in improved battery operation.
There will be SEI growth with the many repeated charges and discharge cycles, which causes the increment in battery impedance, temperature rise, and poor power density.
Functional Properties of SEI
SEI is unavoidable in a battery.
however, the effect of SEI can be minimized if the layer formed adheres to the following
It has to block the direct contact of electrons with electrolyte because contact between electrons from the electrodes and the electrolyte causes degradation and reduction of electrolyte.
It has to be a good ionic conductor.
It should allow the lithium ions from an electrolyte to flow to the electrodes
It has to be chemically stable that means it cannot react with electrolyte and should be insoluble in the electrolyte
It has to be mechanically stablewhichmeans it should have a high strength to tolerate the expansion and contraction stresses during charging and discharging cycles.
It has to maintain the stability at various operating temperatures and potentials
Its thickness should be close to a few nanometers
Controlling of SEI
coatings on electrodes control the SEI growth.
(ALD coating) with the bandgap of 9.9 eV coated on electrode controls and stabilizes the SEI growth due to its slow electron transfer rate.
This will reduce the electrolyte decomposition and Li-ion consumption.
In the same way Aluminium alkoxide, one of the MLD coatings controls the SEI layer build-up.
These ALD and MLD coatings reduce the capacity loss, improves the coulombic efficiency.
article/difference-between-risc-and-cisc-architecture
Difference between RISC and CISC Embedded Architecture
, with mini-computers in biometric door locks, airplanes, cars, pacemakers, etc.
These resources constrained, small, smart and powerful systems help us in our daily tasks.
Ever gave a thought on how our body is functioning, the nervous systems, brain and ability to multi-task.
If you combine all these functions, you would get a rough picture of a biological embedded system.
Our brain hides the complex detail of its functioning that takes place inside it but yet allows us to control it to maximum potential.
The same complexity goes for the processor or controller used in embedded systems.
They hide complex details and provide us a high-level interface to work upon.
For the level of abstraction, one can relate how the code for adding two numbers in a high level programming language cause the registers in the chips handle bits and give an output back to the user.
Processor Architectures
article.
is influenced by the type of architecture used in it.
Let’s take a look at the popular architectures.
was proposed.
In this architecture a separate data buses for data and program are present.
So it means this architecture proposed the use of four buses
A set of data bus carrying the data into and out of the CPU.
A set of address bus for accessing the data.
A set of data bus for carrying code into the CPU.
An address bus for accessing the code.
The Von Neumann architecture may sound a bit lazy but it has the advantage of its simple design.
on the motherboard would make the board complex and expensive.
Let’s understand it with an example of a processor.
is used in which memory hierarchy with CPU cache memory is used for separating the program and data.
Memory hierarchy separates the storage based on the hierarchy of the response time of the processes.
As the program (code) is loaded into the memory of the system (RAM) it is fetched by the CPU (referring both microprocessor and microcontroller) to act on the data, it is much similar as we give instructions when we train the dog for certain actions and commands.
As those instructions are acted upon certain transistors goes from one logic level to another to make that happen.
So basically with the help of instructions human programmer communicates with the processor.
Every CPU has its own instruction set, a collection of instructions based on its architecture and capabilities.
For a human programmer, it’s really difficult to remember the combination of 0’s and 1’s for every instruction that is associated with the CPU.
To keep the job of a human programmer easy, we are provided with high-level interfaces of these instructions and the compiler converts them in the form of 0’s and 1’s for its processing.
Also in the instruction set of each CPU, it has a limited number of instructions that it can understand.
related to the performance of the CPU.
CPU’s generally have a clock rate in MHz (Mega-Hertz) or GHz(Giga-Hertz) like 25 GHz clock rate.
The number associated with the clock rate tells how many times the clock inside the CPU ticks in cycles per second.
The practicality of the clock rate can be understood by the fact that instructions are performed based on clock cycles of the CPU which is proportional to the number of programs CPU can run at a time.
depends upon the number of instructions that are written in the program, more the instructions, more the time taken by CPU to perform them.
It also depends on the number of clock cycles in which each instruction is executed, certain instructions need more clock cycles to be executed than others so they lag the performance of the CPU.
Instructions in a program and cycles required to perform each instruction are inversely proportional to each other.
Changing one will affect the other.
This is the point where the CPU industry is divided.
RISC andCISC Instruction Set Architecture
Complex Instruction Set Computing (CISC)
uses transistors as the hardware to decode and implement instructions.
However, as instruction is complex and constitutes of multiple steps, they are executed in more number of clock cycles.
chapter), we get a CISC instruction.
Reduced Instruction Set Computing (RISC)
were introduced.
may sound a lot hard because of multiple instructions but it is justified by the size of instruction and the fact that each instruction is executed in a single clock cycle.
A simple analogy to understand when one has to perform each step for reading the book by finding the book and then finding the page and then chapter and finally start reading.
Comparing RISC vsCISC Architecture
, there’s no winner between RISC and CISC architecture, it all depends upon the application and scenario of use.
RISC emphasizes efficiency by taking into account cycles per instructions whereas CISC emphasizes efficiency by the number of instructions in a program.
For a better efficiency CISC depends on a few lines of code while the RISC reduces the execution time for each instruction.
Fairly, it’s not possible to compare microcontrollers and microprocessors based on these two architectures on common ground.
Taking an example of an instruction for multiplying two 8-bit numbers, a CISC based processor would approximately take 70-80 clock cycles, whereas a RISC based processor would approximately take 30-40 clock cycles, which makes it 2 times faster than CISC.
Also, as the CISC based CPU’s needs more clock cycles for execution pipelining of instruction is a much harder task as compared to a single cycle processing in RISC based CPU’s.
Where are CISC and RISC Architectures being used?
was present, even though the official name CISC was not there.
But with the introduction of software such as compilers, RISC based architecture was set to development.
Intel from the starting was dependent on CISC architecture.
A few companies which were willing to take the risk on RISC were Apple, Atmel, etc.
After few years CISC became a little obsolete and unpopular because of difficulty in improvement.
However, Intel never left the CISC and continued its development for the improvements.
generation K5 series.
On an Application basis, CISC is preferred for automation devices while the RISC is preferred for video and image processing devices.
article/major-challenges-that-make-setting-up-solar-plant-less-feasible
Challenges that Make Setting up a Solar Farm Less Feasible
Nearly 4.18 trillion kWh of electricity were generated in the United States at utility-scale electricity generation facilities in 2018, and around 17% was generated from renewable sources.
The statistics recently published by the U.S.
Energy Information Administration state that approximately 67 billion kWh of the total electricity generated in the country last year were sourced from solar energy, which accounts for the share of merely 1.6%.
The picture is similar in European countries, where around 17.5% of the total energy consumed in the European Union in 2017 came from renewable sources.
However, the share of solar energy remains significantly low.
, such as declining oil and gas prices and technical difficulties in integrating electric-power grids with solar in a less expensive way.
The opportunities are immense for solar farmers in spite of such issues; however, some important challenges must be taken into consideration while setting up a solar farm and harvesting solar energy.
Hurdles in Harvesting Solar Energy by Setting up a Solar Plant
Solar construction, albeit much less expensive, has become a ‘costlyᾠbusiness in terms of skills.
Though the cost of setting up a solar farm is declining sharply, the other challenges such as dearth of a labour force with appropriate skills and experience and sync with ever-evolving technologies amid the ongoing pursuit for clean energy are making the solar power business less cost-efficient.
Furthermore, other challenges such as varying site requirements, rapidly multiplying equipment vendors, lack of plant performance assessment tools, and low penetration of efficient tools, continue to restrict the adoption of solar energy as a potential source of producing electricity.
However, there are a few basic restrictions that the nature of the solar energy possess, which remain the preeminent blocks for solar farmers today.
The three primary challenges that come with solar energy are its poor dispatchability, its diluted form, and issues with the proximity of a solar farm.
Solar companies will have to adopt a correct approach to understand the most important challenges while setting up a solar farm to drive better performance and productivity in the coming future.
1. Maintaining Reliability and Dispatchability of Solar-powered Electricity
Though the world is moving towards clean and green energy sources, the goal to rely completely on solar power is considered unrealistic.
Consumersᾠdemand and needs vis-à-vis electricity are changing every day during every season, and the uncertainty of the solar resources across various regions make it challenging to ensure 100% reliable energy supply.
It has become important for solar farmers to ensure that electricity supply through solar energy matches the highly dynamic end user demand in order to curtail the possibility of blackouts.
As the dispatchability of electricity generated through solar energy entirely depends on how much the sun shines through various seasons and geographical regions, solar power continues to remain the less reliable energy than that sourced from fossil fuels.
This makes it mandatory for solar power companies to acquire dispatchable power generators than can amplify or ramp down the electricity supply based on the obtainability of the solar energy, which commonly changes every day.
Thereby, farmer must ensure while setting up a solar farm to supplement it with efficient solar generators along with energy storage or batteries, and this can be considered as an additional investment.
However, with the prices of batteries plummeting sharply, complementing a solar farm with battery-supplemented generators should help power companies to overcome this challenge and ensure more reliability of the solar power supply.
2. Dealing with the Problem of Diluteness and Intermittency of the Solar Energy Source
On a clear, bright day, nearly 1 kW of sunlight reaches an area of one square meter on the earth only when the sun is directly overhead, and this can differ greatly geographically.
As solar cells can convert around 15-20% of the solar energy that reaches earth into electricity, the intermittency of sunlight hampers the efficiency of solar power generation.
Furthermore, along with the problem of intermittency, the problem of diluteness of sunlight has always been, and will continue to remain the Gordian knot for solar farmers.
Fossil fuels are the most concentrated forms of sources to generate electricity from, solar energy is dilute on the other hand.
The energy density of the fuel source makes a direct impact on other aspects of setting up a solar farm, including the area of land that it taken up by the farm.
Lower the density, larger the land that is required to meet the electricity demand of consumers.
This reflects in an increased need for additional resources to generate one unit of electricity from solar energy over fossil fuels.
Accomplishing the goal of completely replacing fossil fuels with solar energy as the source for a 100% renewable grid primarily amplifies the need for large areas of land to set up solar farms.
As solar energy is significantly low in energy density, this would have a paramount impact on the land-use requirements for solar power plants, making it a primary challenge for power companies while setting up a utility-scale solar farm.
3. Infrastructural Challenges that Come with the Proximities of Solar Farms
While the intermittency, reliability, and land-related challenges associated with setting up a solar farm remain highly critical, solar power companies need to keep in mind the infrastructural and transportation-related hurdles of the business.
As solar farms take up a huge amount of space to generate electricity that can meet the ever-growing demand, these farms are situated in remote areas, far from where the energy is actually consumed.
Eventually, solar power companies need to deal with the costly infrastructures and cumbersome transmission line to transport electricity from power generation plants to consumers in urban or rural areas.
Though small businesses or residential end users who have enough land to set up a small solar farm can produce their own electricity with solar energy, improving the proximity of their sources on industrial or commercial level becomes a huge challenge in setting up a large-scale solar farm.
In the modern economy, which mainly banks on the equipment and infrastructures that gobble massive amount of electricity, solar farmers must adopt strategies to optimize land efficiency and capitalizing on the more productive ways to transport the electricity over long distances, in order to run a profitable business.
case-studies/dont-use-your-numerical-relay-like-electromagnetic-relay
Don't use your Numerical Relay like Electromechanical Relay
With the experience of working in more than 500 Plants with various types of Electrical services, I have come to know about the different problems Engineers face during Maintenance and Breakdown.
Instead of keeping the exposure limited to me I decided to share it with my fellow engineers here by writing case studies.
One such case study is as follows.
Using Numerical relay to its maximum potential
Many Engineers use Numerical Relay just to see the data, settings and fault records in but they can be used for more than that.
You can yourself do programming on Numerical Relays
You can make logic's which may help in better plant operations
You can use all the binary input and output for better equipment availability and fault discrimination.
And many other things too.
using that Relay Software.
and few more free software is available on their website, which can be downloaded and used to connect your Numerical Relay with Laptop using a communication cable (which you may already have, normally OEM give Communication cable & Laptop during panel supply)
It will help you in finding solutions for many of your plant faults.
If you don't know how to communicate relays, whenever any testing team comes to your plant ask them to teach you.
It will help you while Replacing relays, you can also directly copy settings and configurations them from old relays to new equivalent relays.
You can download the Fault record or Event Record and you can analyze the fault and may be able to reach on a conclusion.
About the Author
is an Electrical Engineer with over 11 years of rich experience in Electrical Maintenance, Installation, Testing, and Commissioning of all major Electrical equipments.
He is specialized in bringing down Energy Cost of a Plant by reducing electricity bills and increasing energy efficiency.
He also reduces plant breakdown cost by implementing proper maintenance activities during routine and shutdown.
Through these Case Studies he shares his experience and challenges faced in his work routine with the readers of Circuit Digest.
article/how-machine-learning-and-ai-are-transforming-supply-chain-management-systems
How Machine Learning and AI are transforming Supply Chain Management System
, the convergence of technology with various production processes, including supply chain and logistics, has become an indispensable part of doing business today.
Businesses are voicing the need for tools to further enhance supply chain visibility and traceability, defining a new way to do amplify profits in the Information Age.
Consequently, the digital transformation of the supply chain management system is emerging as one of the latest trends in the biz world.
with the supply chain management systems, manufacturers have been able to achieve high levels of efficiency at closing the gap between supply and demand.
Adoption of AI and ML to Grow Vastly in Supply Chain Optimization
A survey was recently published by JDA Software, Inc.
ᾠan American software company ᾠand KPMG LLP ᾠa multinational consulting company ᾠfound that more than three-fourth of the respondents considered visibility and traceability of supply chain as the highest investment areas for supply chain executives.
The survey also found that nearly 80% of the respondents viewed AI and ML as the most impactful technologies in this landscape owing to their applicability in dealing with the complex issues in supply chain and value chain systems.
With predictive end-to-end visibility becoming one of the most important aspects in the modern ways to optimize supply chains, the ubiquity of AI and ML tool will increase dramatically in the supply chain management systems in diverse industrial areas.
As AI and ML are emerging as some of the most impactful technologies in the supply chain operations of any business, investment in these technologies will remain on the upward swing.
However, it is of the immense importance to understand the exact impact of AI and ML, together, on supply chain management to ensure to capitalize on these technologies to their fullest potential.
Artificial intelligence in supply chain management not only automate the process but also take decisions on procurement, inventory management, supply logistics etc without any human intervention.
Implementing AI/ML in the Management of VUCA as a Supply Chain Strategy
VUCA are the major roadblocks for standardizing supply chain management processes, and businesses how found a way to tackle these issues with advent of the advanced technologies such as AI and ML.
It is gaining popularity as an effective way to manage VUCA by integrating Artificial Intelligence and Machine Learning in supply chain management systems and logistics, which can not only identify but also define the contingencies throughout various processes.
With the adoption of AI and ML-based tools in supply chain management, manufacturers have been able to manage ambiguities, complexities, and other VUCA challenges associated with high-tech products, while the trend of Industry 4.0 continues to remain on the rise.
Role of Artificial Intelligence in Supply Chain Management
As robotic process automation is becoming an inevitable part of most industrial operations as well as equipment, supply chain management systems are also undergoing a digital transformation.
Thereby, technologies such as AI and ML are the part of not just manufacturing equipment, but also supply, value chains and warehouse management which mainly thrive on quick yet accurate decision-making.
The relentless pressure of making appropriate decisions faster than ever is triggering manufacturers to use AI and ML techniques to reducenot replace human interference in supply chain management.
Most AI and ML-aided tools implement human reasoning techniques as a model when they are integrated with decision-making processes in supply chain management, and this improves the speed and accuracy of insights about product as well as trends that are finally attained by such protocols.
As delayed decisions can have a significant impact on profits, revenue, cash flow, and even customer satisfaction in some cases.
Thereby, AI and ML are enabling manufacturers to increase the speed of decision-making protocols in high-tech supply chain management systems.
With the positive impact of AI and ML-powered tools on decision-making processes in supply chain, its adoption is likely to influence positive growth of businesses undergoing digital transformation.
AI and ML Techniques Influence a Synchronized Approach to Supply Chain Planning and Optimization
Supply chain management is always considered an interconnection of various data-driven and analytical processes, and synchronization of such huge amounts of data becomes imperative to ensure accurate supply chain planning.
Furthermore, the increasing complexity of tech-driven supply chain has been bringing in a fundamental shift in the way the process of synchronized planning is carried out to ensure the optimization of supply chain.
AI and ML-powered tools are entering the supply chain planning landscape, facilitating the transition from a static to a dynamic sequence of multiple supply chain operations.
Such tech-driven tools are being incorporated in today’s supply chain management systems, and this is highlighting their benefits in synchronizing end-to-end supply chain planning.
These tools can also be used to automating procedures to match demand and supply as well as decision-making processes in real-time, which ultimately synchronize the planning ecosystem in the supply chain landscape.
Challenges in the Adoption of Artificial Intelligenceand Machine Learningin Supply Chain Management
Though the global industrial landscape is making a move towards the adoption of next-generation technologies to bolster digital transformation, the adoption of these technologies in niche areas such as supply chain management remains significantly low.
The gap between the hype of technologies such as AI and ML and the actual technological value is mainly attributed to the limitations in adoption of tech-driven tools in supply chain management.
Most managers and business executives fail to understand and visualize the exact benefits and impacts of AI and ML in supply chain management in the growth of business.
Furthermore, AI and ML tools require periodic maintenance to ensure flawless working within the expected parameters of supply chain management systems, which translated into an additional cost.
Such challenges have been heavily hampering the penetration of these technologies across all geographical regions in the world.
However, as the awareness about the dramatically positive influence of AI and ML in supply chain management is growing rapidly, its adoption will become inevitable in the coming years, despite these challenges.
tutorial/how-to-design-your-own-transformer-for-smps-power-supply-circuits
How to Design your own Transformer for SMPS Power Supply Circuits
article to better understand the proceedings.
Parts in a SMPS transformer
as well.
For instance, here is a datasheet of popular core EE25.
material from a widely popular core manufacturer TDK.Each and every bit of information will be needed for transformer construction.
However, Cores have a direct relationship of the output wattage, thus for different wattage of SMPS different shape and size of cores are required.
based on its wattage rating.
Maximum Output Power
Ferrite cores forTIWconstruction
Ferrite cores for Margin Wound construction
0-10W
EPC17,EFD15,EE16,EI16,
EF15,E187,EE19,EI19
EEL16,EF20,EEL19,EPC25,EFD25
10-20W
EE19,EI19,EPC19,EF20,
EFD20,EE22,EI22
EEL19,EPC25,EFD25,EF25
20-30W
EPC25,EFD25,E24/25,EI25,EF25,EI28
EPC30,EFD30,EF30,EI30,
ETD29,EER28
30-50W
EI28,EF30,EI30,ETD29,
EER28
EI30,ETD29,EER28,
EER28L,EER35
50-70W
EER28L,ETD34,EI35,
EER35
EER28L,ETD34,EER35,
ETD39
70-100W
EPC30,EFD30,EF30,EI30,
ETD29,EER28
EER35,ETD39,EER40,E21
are illustrated below with help of images.
which provides the information of primary windings.
The commonly used EE16 transformer bobbin is shown below
In an SMPS schematic, you can notice the high voltage DC from the high voltage capacitor connected with the primary side of the transformer and the other end is connected with the power driver (Internal mosfet drain pin) or with a separate high voltage MOSFET's drain pin.
However, the output or low voltage side of an SMPS circuit is generally connected to the secondary winding.
One side of the secondary winding is the DC, GND and the other side is connected across the output diode.
As discussed, an SMPS transformer can have multiple outputs.
Therefore an SMPS transformer can also have multiple secondary windings.
The auxiliary winding is used to provide this additional voltage to the driver circuit.
For example if your driver IC is operating on 12V then the SMPS transformer will have an auxiliary output winding that can be used to power this IC.
are used with different width for different types of bobbins.
The thicknesses of the tapes are required to be 1-2mil for providing insulation.
Transformer Design Steps:
Now that we know the basic elements in a transformer we can follow the below steps to design our own transformer
Find the right core for the desired output.
Choose the right cores listed in the above section.
Finding out the Primary and secondary turns.
to calculate the primary and secondary turns are-
Where,
Np is the primary turns,
is the secondary turns,
is the minimum input voltage,
is the drain to source voltage of the Power Mosfet,
is the output voltage
is the output diodes forward voltage drop
is the maximum duty cycle.
of the secondary winding.
The next stage is to find out the transformers primary inductance.
This can be calculated by the below formula,
Where,
is the output power,
z is the loss allocation factor,
n is the efficiency,
is the switching frequency,
is peak primary current,
is the ripple current to peak ratio.
Next stage is to find out the effective inductance for the desired gapped core.
rating.
If the value is not available one can add spacers between the cores or grind it to get the desired value.
in millimeters is
is the number of primary turns.
in millimeters is-
is the number of secondary turns, and M is the margin on both side.The wires need to be converted in AWG or SWG standard.
In such case parallel wires can be constructed.
In parallel wire winding, that means when more than two wires are needed to be winded for the secondary side, the diameter of each wire can behalf of the actual single wire value for easier winding across the secondary side of the transformer.
This is why you find some transformers having dual wires on a single coil.
where we used PI Expert to build our own transformer using the points discussed so far.
for faster response.
article/diabetes-monitoring-the-next-big-move-for-wearable-industry
Diabetes Monitoring ᾠThe next big move for Wearable Industry?
which are helping to decrease the involvement of doctors and hospitals and thus challenging the orthodox techniques of this industry.
Medical Wearable Industry
Factors like aging, growing population, prevalence of chronic disease lead to exponential advances in innovative but costly digital health care technology.
The health care industry is expected to set a new high of USD $ 10.059 trillion in term of 2017-2022.
The medical wearable industry is witnessing a growth at CAGR of 26.1 % over the forecast period of 2018-2022 and was valued at 10.3 billion in 2018, which forecasts a value of 20.04 billion in 2022.
which are the part of the wearable medical devices is also witnessing a positive momentum in patent filing trend and is rising since this decade.
The Patent publication trend graph for SDMD devices over the recent years is shown below.
Diabetes ᾠAn Epidemic disease
A new state of Diabetes Monitoring using Wearable Devices
such as sweat.
Many companies are building these devices and are integrating them into small packages so that they don’t create any hindrance in our daily routines.
Companies leading with Wearable Diabetes Monitoring Devices
measurement.
Dexcom is known for manufacturing compact glucose monitoring devices, this strategic launch would definitely attract more buyers increasing the company’s revenue and would definitely be a monopoly for the premium health care device market.
Launch of this feature would not only help to monitor blood glucose level but also detect the conditions ahead of time.
which leads to a mini bluetooth enabled pump system working with Tidepool Loop, an open-source iPhone and Apple Watch app.
The system includes a sensor that is placed on the upper arm for 14 days to read glucose information.
The sensor is connected to the application for reading the glucose levels, at whole the system eliminates the need for the finger prick system for glucose testing.
The app also gives suggestions about the food a person should eat to help for controlling diabetes through exercise and proper diet.
and medical wearables that provide more control on health than ever before.
that promise to streamline diabetes management.
These tools are smart that they can maintain a patient profile along with vital signs and health analytics, and determine risk levels.
The shoes and socks developed by scientists for people with diabetes.
These wearables are Pre-installed with pressure and heat sensors to detect areas of the foot with inadequate blood supply, reducing the development of foot ulcers and lower the risk of amputations.
is a small capsule that works like natural pancreas.
This capsule is loaded with the stem-cell so as to produce insulin.
scientists are also working on several other implants that could help to automatically deliver drugs and insulin based on blood glucose levels.
Integrated and Closed Loop Apps and Devices
can not only measure the level glucose in your blood, but can also administer you with the required dosage of insulin.
to help keep blood glucose levels in a safe range.
System developed by Senseonics.
consists of a fluorescence-based sensor, a transmitter, and a mobile app which provides real-time glucose monitoring in every five minutes for up to 90 days.
It displays trends, alerts related to glucose values on the mobile device.
Continuous Glucose Monitors (CGM) Device Market
is a must which allows people to responsibly self-check their health indicators.
The Healthcare Industry is one of India’s largest sectors - both in terms of revenue and size.
Continuous glucose monitoring (CGM) devices and insulin pumps measure glucose levels from fluid under the skin without pricking it.
The readings from CGMs helps to advise the doctors/ patient’s what course of action to be taken, or in the case of emergencies, information can be sent immediately to healthcare providers.
Currently, the market of CGM devices prevails primarily in the North American and Europe.
The device market would be expanding in emerging markets such as Asia, Africa, and the Middle East.
The current demand from the companies is to create more efficient treatment devices, in terms of both ease of use and cost, that would help diabetics to properly manage their condition.
, Continuous glucose monitoring devices(CGM), Insulin Pumps, Patches, Diabetes Apps, Services, Data Management Software’s, Hand-held & Wearable devices and pumps.
Some of the Global major player’s in digital diabetes management market are Medtronic (Ireland), B.
Braun (Germany), Dexcom (US), Abbott Laboratories (US), Roche Diagnostics (Switzerland), Insulet Corporation (US), Tandem Diabetes Care (US), Ascensia Diabetes Care (Switzerland), LifeScan (US), Tidepool (US), AgaMatrix (US), Glooko Inc.
(US), and DarioHealth (Israel).
The market for continuous glucose monitors and digital diabetic control devices is getting crowded as technology is advancing.Additionally, research is being carried out to lower the risks of proven diabetic diseases such as blindness, kidney failure, heart attacks, strokes and lower limb amputation.
This would help in bringing down the incidence as well as mortality associated with diabetes.
case-studies/what-could-cause-repeated-relay-failures-in-chemical-plants
What could cause repeated relay failures in a chemical plant?
We thought it was important and must be brought to notice to all concerned people working in O&M or Project in chemical industries to take due note of it as it may help other industries who doesn’t know about it.
Repeated Failure of Substation / Load center Relays
of a good branded MNC OEM.
The plant was commissioned in 2013-14 and after 2-3 years of commissioning and full plant run-up, few of the relays in 2 substation / Load center started giving error on display.
As the plant had many HT / LT spare and changeover feeder, they replaced the relay (showing error) with spare relays.
But after every 2-3 month such kind of error started coming in other relays of same substation.
When almost all the spare working relays were replaced, it strikes the Maintenance team, that something is not right.
(which is normally DC) and Battery bank / Charger to see if there are any fluctuations in DC voltage or not.
Because normally heavy fluctuation in Auxiliary voltage causes problem in relay and sometimes even fails the relay.
But no problem was found in Auxiliary supply, battery bank / charger or even wiring.
Gas in Chemical Plant causing Relay Failure
in 2-3 years of installation, which is unacceptable.
Taking due notice of the Maintenance team, OEM acted very promptly (As the Organization was one of their prime customers since decades) and took 3-4 relays for analysis.
After thorough analysis of Relay, which took roughly 2 months, they found the problem, which was some Gas which was there in such kind of chemical industry.
And this problem was more in the 2 substation which was nearer to the chemical process area.
Far end substation saw very rare such problem in relays.
Conformal Coating mandatory for Relay Protection
on the Electronic Circuits (PCBs) of Relays.
Some Engineers among you might ask Why Conformal Coating? What does Conformal Coating do here to prevent the problem? The answer is bulleted below.
Importance of Conformal Coating
This coating provides protection against extreme moisture, corrosive gases and agents (Like H2S, Chlorine, etc) and aggressive dust, or combinations thereof.
It acts as an Additional layer of protection for the electronic circuits on PWBs
Furthermore, the coating layer also offers mechanical protection against inappropriate handling and external influences.
Conformal coating extends the lifetime of your devices in case of harsh environments.
) and even if that part was missed by the user, that should have been brought to Notice by OEM.
In this and many such cases both User and Vendor miss such minor details.
Obviously, there are many other things to work, why to go so in-depth details of equipment whose cost is not even 0.01% of Total project cost.
will be required in your Plant or Not?The same is valid for other Electronic Equipment’s.
Remember Conformal Coating will come at some Extra Cost.
Credit of this case study goes to discussion between undersigned and HOD Electrical of a Chemical Plant recently.
About the Author:
is an Electrical Engineer with over 11 years of rich experience in Electrical Maintenance, Installation, Testing, and Commissioning of all major Electrical equipments.
He is specialized in bringing down Energy Cost of a Plant by reducing electricity bills and increasing energy efficiency.
He also reduces plant breakdown cost by implementing proper maintenance activities during routine and shutdown.
Through these Case Studies he shares his experience and challenges faced in his work routine with the readers of Circuit Digest.
case-study/ht-motor-tripping-with-overcurrent-fault-during-grr-control
HT Motor Tripping with Overcurrent fault during GRR Control
This type of problem is pretty rare in industries and hence would like to share the experience, so that the problem we faced will not be faced by others or can be avoided altogether.
But during modification, the engineers overlooked one condition, which did not seem so big initially but then it tripped the complete plant.
Before we get into the actual problem, let’s get few things straight by answering these questions.
GRR stands for Grid Rotor Resistance, where a 3 phase resistance of the motor is changed on basis of changing few combination of power contactors.
It is commonly used at places where motor speed needs to be controlled (Mostly in Fans, Fan speed depends on Process requirement and Air flow required in a system)
will never be on at same time.
It also receives command from DCS and to increase or decrease rotor resistance, for controlling the speed of fan.
The team realized that this Fan PLC was creating some problem, due to which there was trouble in increasing or decreasing the speed of fan.
The plant also tripped completely twice because of this problem.
So, team decided to remove the PLC and take all the DI, DO and feedback to DCS and make a program just like PLC in their DCS, so as to remove the local PLC and reduce breakdown and malfunctioning.
Slip Ring Induction Motor tripping with Over Current Fault
Project was taken and was done during shutdown, every input and output was checked and configured.
Just like PLC a program was made for DCS which removed the Local PLC.
With the PLC bypassed, the team decided to take trial of fan during shutdown, to ensure that everything is right.
, inspected motors health and started again.
The Motor started again normally but after that same step,it tripped again for over current.
Atleast this time they got that something is wrong after 8th step of GRR, as till 8th step the motor runs fine and as soon as GRR goes to 9th step, the motor gets tripped.
But the resistance was balanced for each step and every phase.
GRR Step is given below.
This problem was not solved till 2 days.
Both day trial taken 2 times and complete GRR and motor was checked.
Till 8th step of GRR, everything is fine and as soon as it goes ton 9th step Motor trips.
They asked in some other plants, one told them “increase the time delay between change of stepsᾮ
Now we knew the problem was in delay.
I looked again it into GRR 8th and 9th step and then realize what time delay has done.
How did time delay solve the over current problem?
and consequently tripping of Motor.
So the question was during Step change Contactor should drop first or Pick-up first? It was great learning, a simple PLC logic was tripping our HT motor.
Do share this with your colleagues in your Plant, Electrical Dept of other plants and your friends, It may save their Generator or Motor .
About the Author:
is an Electrical Engineer with over 11 years of rich experience in Electrical Maintenance, Installation, Testing, and Commissioning of all major Electrical equipments.
He is specialized in bringing down Energy Cost of a Plant by reducing electricity bills and increasing energy efficiency.
He also reduces plant breakdown cost by implementing proper maintenance activities during routine and shutdown.
Through these Case Studies he shares his experience and challenges faced in his work routine with the readers of Circuit Digest.
article/understanding-autosar-and-its-architecture
Understanding AUTOSAR and it’s Architecture
which was jointly developed by automobile manufacturers, suppliers and tool developers.
In this article we will learn what is AUTOSAR and about the different layers in its architecture.
so that the outcome of the process can be delivered without the need of any alterations.
AUTOSAR ᾠHow it all began?
by considering the different automotive E/E architecture that were present and that tie and would be formed in the future.
are BMW Group, Bosch, Continental, DaimlerChrysler, Ford Motor Company, General Motors, PSA Peugeot Citroen, SiemensVDO, Toyota Motor Corporation, and Volkswagen.
Importance of AUTOSAR
increases the competition in the automotive industry will also increase.
All this intelligence and vehicle functionality can’t be implemented by a single authority.
by different automotive industries, so all the different automotive units should able to work hand in hand to get the desired outlet.
This also helps in software development process, because until recent time the software developed for automotive industries was only focused on delivering the functionality of the system and they never cared about what are the effects it can provide to the system.
It got more complicated due to a lot of functionalities over various ECUs across different vehicle networks.
It became a more critical problem with the increase in non-standard development procedures.
Hence, they have developed the AUTOSAR.
Different Layers of AUTOSAR Architecture
If you look into the above image you can identify that the AUTOSAR’s architecture is made of three main layers which are
Application Layer
Runtime Environment (RTE)
Basic Software (BSW)
Each of these layers has its own purpose and has a specific operation to perform
The software components ensure the functionality of the subsystem, which involves the operations and data elements that the software requires and the resources needed by the components.
And the source of the application is independent of the location of the interactive components, the type of ECUs on which the component is mapped on and the number of times the component is instantiated in a system.
The runtime environment layer creates a suitable environment for the operation of the software components (SWCs).
The SWC is always dependent on the interface provided by the RTE.
where the Base software had the permission to call any API function or other modules directly, but the Application software can only communicate through ports.
The RTE is generated in Two Phases
Contract Phase: This phase is independent of the ECU and it provides the contract between the application software and the RTE that is, the API of the ASW components can be coded against.
It has resulted in an ASW component specified header that we can include in the source code.
The header file consists of all the RTE API functions that can be used in the ASW and also the necessary data types and structures needed by the ASW components are declared in the Header file.
Generation Phase: This phase will focus on generating the concrete code for a given ECU.
With the ASW components and Header Files created in the contract phase and all necessary BSW code, the generated code can be compiled into an executable file for the ECU.
The Basic Software layer can be defined as the standardized software that can provide services to the AUTOSAR software components and it is also used to run the functional part of the software.
The Basic software includes the standardized and ECU specified components.
The Basic Software layer is further divided into 4 Major parts namely Services Layer, ECU Abstraction Layer, Microcontroller Abstraction Layer and Complex Drivers.
hardware.
The service layer provides functions such as
Memory Services (NVRAM Management)
Diagnostic services (Including UDS <protocol> communication and error memory)
Vehicle network communications and management
ECU state management
Operating System (OS)
, Parts of the ECU hardware and their applications.
This layer acts as an interface of the micro-controller abstraction layer which also contains some drivers of external devices.
It has access to the peripherals and the devices no matter where they are located either inside or the outside of the micro-controller.
It also offers the API to interface with the micro-controller.
is a hardware layer designed to ensure the standard interface to the components of basic software.
It provides micro-controller independent values for the components of the basic software and also manages the micro-controller peripherals.
Bus.
The CDD is used for handling complex functions, it can’t be found in any other layers and it has the ability to access the microcontroller directly.
The complex functions include injection control, Control of electrical values, Position increase detection, etc.
Objectives of AUTOSAR
AUTOSAR was created for certain reasons that are helpful for the present and which will be helpful in the future also, some of the objectives are listed below.
Implementation and standardization of basic functions as an industry-wide “standard coreᾠsolution.
Integrations of functional modules from different suppliers.
Easy to maintain the process throughout the life cycle.
The ability to scale different vehicles independent of the platform.
Redundancy activation.
Consideration of availability and safety requirements.
Easy transfer of functions from one ECU to another ECUs within the network.
Using commercial off the shelf (COTS) hardware more.
Regular software updates and upgrades throughout the lifetime of the vehicle.
Benefits of AUTOSAR
AUTOSAR serves different benefits in different stages of the vehicle’s life cycle
With AUROSAR you can use the same software code again and again for different OEMs.
It is more flexible to adapt for different designs and also reduces the time and cost of production.
Suppliers can increase their efficiency of functional development and create their own business model that is suitable for them.
AUTOSAR has a common interface that helps the tools provider to standardize their development process.
For the new entrants AUTOSAR acts as a transparent and defined interface that can help them understand the industry standards and also to create their own business models.
What can you expect through AUTOSAR?
and it has no application of its own.
It has an OS with basic functions and interface softwares and the main advantage is that the same interface can be used in all basic software.
The functionalities of AUTOSAR are supplied as software components and all the components involved are hardware independent.
article/what-is-industry-4-and-its-nine-technology-pillars
The Nine Pillars of Industry 4.0 - Transforming Industrial Production
, this is the German translation of Industry so both can be used interchangeably.
Industrial Revolutions
Almost every review paper, white paper or blog that you read about Industry 4.0 would have a piece about former industrial revolutions.
We will also discuss briefly about previous industry revolutions.
First Industrial revolution is the transition from manual labor to steam engine where the mechanical advantage of steam engines was leveraged to lessen the human labor.
replaced the steam engine.
There was little to no manual labor involved.
Mass production assembly lines were introduced during this period.
and electronics in factories and industries made it possible for humans to program the electrified machines and third industrial revolution was born.
It eventually paved way for automation.
ᾮ All the three Industrial revolution that the world has seen comply with the above definition.
Does the fourth Industrial Revolution “Industry 4.0ᾠdo the same? Let’s find out‐
What is Industry 4.0?
ᾮ
and Europeans call it- Industry 4.0 (Germans came up with the term).
So don’t be baffled when you hear terms like smart factory and Industrial IOT.
They all refer to Industry 4.0 as there is no consensus about how we call it.
A Cyber physical system plays a vital role in Industry 4.0 and is changing the face of the industry.
It again is a fancy name for the physical systems with electronics embedded in them for making them intelligent.
The Nine Pillars of Industry 4.0
and shall try to apply the technology to the facility and witness the regular factory turn into a smart one.
1) Big Data and Data analytics
Data analytics, once an IT application is now penetrating into manufacturing and supply chain industry.
Power of data analytics and pattern recognition can be harnessed in the manufacturing industry to reduce downtime and wastages.
In our facility, data can be collected at different levels of manufacturing process.
If a PCB or a batch of PCBs is found to be faulty, their manufacturing data can then be retrieved and comprehensively evaluated to arrive at a pattern.
Process involving those patterns can be redesigned and re-evaluated to reduce wastage and increase productivity.
Predictive maintenance can be carried out based on the data collected.
This is cost-efficient and safer than the conventional routine maintenance method.
2) Simulation
A simulation, in present day is used to design components that are manufactured.
In Industry 4.0, it can be used to simulate a virtual environment of the factory itself with the real time data and analyze the productivity before a change in the factory can be made.
This helps engineers to visualize the design in a much better manner consequently helping them identify problems and obstacles in the early stage.
Consider that in our manufacturing facility, we have three robots to solder the PCBs.
With this in mind, our sales team promises the clients that their order will be delivered in 3 weeks.
Unfortunately, one of the older robots faces some technical glitch with deadline in 10 days.
Simulations with different speed of work can be operated to arrive at an optimum speed at which the robots can operate without frying themselves up and meet the deadline.
Else, we either end up missing the deadline by operating two robots at normal speed or run the risk of damaging the working robots with trial and error method.
3) Horizontal and Vertical Integration
Horizontal integration takes networking among the cyber-physical systems and enterprise systems to an unprecedented level.
Every device and system at the same level of manufacturing in the same facility or the other is connected with each other.
As this enables communication between systems in different facilities, jobs can be planned and adjusted by the machines themselves.
Downtime at a facility can be compensated by overtime at another facility with no human intervention whatsoever
Vertical integration makes it even better.
Every system and humans at all hierarchy has all the data with required abstraction.
Notable challenge faced in vertical integration is the communication protocol.
It is insane to expect all the systems to talk the same language which they obviously don’t.
This can be overcome by using interfaces; Quite a painful job but worth the work.
4) Industrial Internet of Things
, I bet.
An ecosystem in which all the sensors and actuators with the ability to function separately and communicate with every other element is called IOT.
Industrial IOT is the same but with increased ruggedness to survive the harsh environments of the industry.
Consider that our factory has run out of solder.
There is no point in pushing out batches of printing circuit boards when there is no solder lead available to integrate the components.
Instead of a human stopping the process, solder lead holder enabled with sensors could prompt the inventory team to buy more solder in prior.
If the inventory team had failed to refill, the printer (etcher) can be turned off or can go in idle mode after receiving a signal from the solder holder.
5) Autonomous Robots
Autonomous robots transfer raw materials, half-finished and completed goods in an easier, faster and smarter way.
They operate based on a complex logic algorithm, meaning they don’t require any preset path to carry out their duties.
These robots catalyze the manufacturing process.
The amount of time that can be gained and latency that can be cut down is equal to the amount of time taken to program controlled robots.
Unlike the conveyor belt, it is portable and its duty can be varied.
you made for your project has applications after all.
In our case of PCB manufacturing factory, these autonomous robots can be used to move the PCBs, once fully completed to the packaging area.
If the manufacturing facility is revamp and the packaging location is changed, just a change of destination in the robot’s system would suffice to operate normally.
6) The Cloud
Cloud is a remote system that can be accessed provided from anywhere using the internet.
There are a lot of cloud services available today of which notable are IaaS, PaaS, SaaS.
Communication among machines themselves and between machines and humans are hugely backed by cloud services.
Amazon.com Inc.
is the best example.
A consumer gets updated about the whereabouts of his order in real time.
This is not a one-to-one message.
Once your package has arrived at the warehouse, information is updated in cloud which is then notified to you.
Every time you check for your package’s present location, get query is executed in real time to let you know about your package.
This can be integrated in PCB factory and supply chain.
Under the topic of Data analytics we already have discussed about placing sensors in different locations of manufacturing.
These can be stored in the cloud which is available for anyone with credentials.
They can be accessed by employees to take required actions there and then as necessary.
Customers would be extra happy and satisfied to view the real time data of their product being manufactured unless we have delays due to technical glitches.
7) Cyber Security in Industry 4.0
Cyber security becomes the talk of the town since the dawn of Information technology.
The greatest nightmare of any information technology firm is having their server and data hacked.
Preventing such a catastrophe and safeguarding the data and performance of the server is the sole purpose of cybersecurity.
As more and more components get connected and one device’s action is based on the output of another device, more operational decisions are decentralized, more security concerns are raised.
Think of the consequences if someone hacks into our system and changes the PCB design and erases his digital footprints.
Earlier, sole way to steal the PCB design would be to physically log into the machine that has the same.
Connectivity makes the system vulnerable to anyone in the same network to access the designs.
comes into play.
Theft and intentional obliteration can be checked through the same.
Integration of the system with cloud by itself advocates the need for cyber security.
8) Augmented Reality
Augmented Reality based systems are storming the technology industry.
Few years ago they found their applications only in flight simulators.
Today remote repair instructions can be sent to literally any part of the earth with internet accessibility.
It helps technicians to enhance their skills by practicing high end repairs and maintenance over and over again using augmented reality.
Consider for example, we have an equipment worth of some million dollars needing some form of maintenance.
Before carrying out the job on the actual equipment, a training session can be conducted.
Once the technician is confident enough to be impeccable, he can do the same with the actual equipment.
It is a win-win situation.
We don’t lose our equipment; Technician does not get embarrassed messing up the job.
9) Additive Manufacturing and 3D Printing
to make prototypes and Proof of concepts.
The flexibility of Industry 4.0 allows us to design complex designs which are nearly impossible with conventional manufacturing processes.
Most of the conventional manufacturing processes are subtractive manufacturing which includes wastage of raw materials.
Additive manufacturing drastically reduces if not totally eliminate the wastage of raw materials.
A company named "made in space" has plans to construct satellites in space.
This has a lot of added advantages.
Densely packed raw materials can be sent to space where they can be used to construct objects of bigger volume.
Satellite designs, that were cost efficient but too fragile to survive the rocket launch forces, can be manufactured in outer space.
Why should you adopt Industry 4.0?
Like it or not, but the use of Industry 4.0 is growing rapidly and your competitors are adapting it.
Not all the nine technological pillars are required in all industries and fields but failing to make the most of it makes your competitors stronger.
Giants like Amazon, Tesla motors, Lockheed Martin, Hyundai, and Boeing are busy transcending to the next level which is Industry 4.0.
Staying stagnant may not just inhibit your success but kill your business.
It is simple as that.
Grow or Perish.
All the customers look for smarter manufacturing, connected supply chain and value added product & service, which can be easily deliverable through Industry 4.0.
It is out there to be used.
So be the part of Industry 4.0 revolution and become the part of new era.
article/an-overview-of-li-ion-batteries
All You Need to Know About Li-ion Batteries
In this article, our interest would be over the Li-ion Batteries since they tend to be more useful than all other types.
Be it a small power bank or a Laptop or something as big as the Tesla’s new Model 3 everything is being powered by a Lithium-ion battery.
What makes these batteries special? What should you know about it before you use one in your projects/designs? How will you charge or discharge these batteries safely? If you are curious to know the answers for all these questions then you have landed on the right article, just sit back and read through while I will try to keep this as interesting as possible.
Lithium-Ion Battery History
The idea of Lithium Ion battery was first coined by G.N Lewis in the 1912, but it became feasible only in the year 1970’s and the first non-rechargeable lithium battery was put into commercial markets.
Later in 1980’s engineers attempted to make the first rechargeable battery using lithium as the anode material and were partially successful.
They failed to notice that these types of lithium batteries were unstable during the charging process and it would create a short inside the battery increasing the temperature and causing a thermal runaway.
In 1991, one such lithium battery used in mobile exploded over a man’s face in Japan.
Only after this incident it was realised that Li-ion batteries should be handled with extreme caution.
A huge number of these types of batteries that were into the market were then recalled by the manufacturers over safety issue.
Later after much research, Sony introduced the advanced Li-ion batteries with a new chemistry which is being used till date.
Let’s wind up the history lessons here and look into the chemistry of a Lithium Ion battery.
Li-ion Battery Chemistry and working
As the name obviously indicates, the Lithium Ion batteries use the Lithium ions to get the job done.
Lithium is a very light metal with high energy density, this property enables the battery to be light in weight and provide high current with a small form factor.
Energy density is the amount of energy that can be stored in per unit volume of the battery, the higher the energy density the smaller the battery will be.
Despite the overwhelming properties of lithium metal, it cannot be used as an electrode directly in the batteries since lithium is highly unstable because of its metallic nature.
Hence we use lithium-ions which more or less has the same property of a lithium metal but it is non-metallic and is comparatively safer to use.
Normally the Anode of a Lithium battery is made of Carbon and the Cathode of the battery is made using Cobalt oxide or some other metal oxide.
The electrolyte used connecting these two electrodes will be a simple salt solution that contains lithium ions.
When discharging the positively charged lithium ions move towards the cathode and bombard it until it becomes positively charged.
Now since the cathode is positively charged it attracts negatively charged electrons towards it.
These electrons are made to flow though our circuit thus powering the circuit.
Similarly while charging, the exact opposite happens.
Electrons from the charges flow into the battery and hence the lithium ions move towards the anode making the cathode to lose its positive charge.
Introduction to Lithium Ion Batteries
is shown in the image below
, so you need higher voltage specification you have to combine two or more cells in series to attain it.
By default all the lithium ion cells will have a nominal voltage of only ~3.6V.
This voltage can be allowed to go down upto 3.2V when fully discharged and go as high as 4.2V when fully charged.
Always remember that discharging the battery below 3.2V or charging it above 4.2V will damage the battery permanently and might also become a recipe for fireworks.
Lets breakdown the terminologies involved in a 18650 battery so that we can understand better.
Keep in mind that these explanations are applicable only for a single 18650 cell, we will get more into Li-ion battery packs later, where more than one cell is connected in series or parallel to get much higher voltage and current ratings.
The nominal voltage is the actual voltage rating of an 18650 Cell.
By default it is 3.6V and will remain the same for all 18650 cells despite of its manufactures.
An 18650 cell should never be allowed to discharge below 3.2V, failing to do so will alter the internal resistance of the battery which will damage the battery permanently and might also lead to explosion
The charging voltage for lithium ion cell is 4.2V.
Care should be taken that the cell voltage does not increase 4.2V at any given time.
The capacity of a cell is normally given in terms of mAh (Milli Ampere hour) rating.
This value will vary based on the type of cell you have purchased.
For example let’s assume our cell here is 2000mAh which is nothing but 2Ah (Ampere/hour).
This means that if we draw 2A from this battery it will last for 1 hour and similarly if we draw 1A from this battery it will last for 2 hours.
So if you want to know how long the battery will power you project (Run-time) then you have to calculate it using the mAh Rating.
Run Time (in hours) = Current drawn / mAh Rating
Where, current drawn should be within the C rating limit.
If you ever wondered what is the maximum amount of current that you can draw from a battery then your answer can be obtained from the C rating of the battery.
The C rating of the battery again changes for each battery, let’s assume that the battery we have is a 2Ah battery with 3C rating.
The value 3C means that the battery can output 3 times the rated Ah rating as its maximum current.
In this case it can supply upto 6A (3*2 = 6) as the maximum current.
Normally 18650 cells have a 1C rating only.
Maximum current drawn from battery = C Rating * Ah Rating
Another important specification of a battery to notice is its charging current.
Just because a battery can supply a maximum current of 6A does not mean it can charged with 6A.
The maximum charging current of a battery will be mentioned in the datasheet of the battery since it varies based on the battery.
Normally it will be 0.5C, meaning half the value of the Ah rating.
For a 2Ah rating battery the charging current will be 1A (0.5*2 = 1).
The minimum charging time required for a single 18650 cell to charge to can be calculate by using the value of charge current and Ah rating of battery.
For instance a 2Ah battery charging with 1A charging current will take approx 2 hours to charge, assuming the charger only uses CC method to charge the cell.
The health and capacity of a battery can be predicted by measuring the internal resistance of the battery.
This is nothing but the value of resistance between the anode (positive) and cathode (negative) terminals of the battery.
The typical value of IR of a cell will be mentioned in the datasheet.
The more it drifts from the actual value the less efficient the battery will be.
The value of IR for a 18650 cell will be in range of milli ohms and there are dedicated instruments to measure the value of IR.
mode starts where the charging voltage is maintained typically at 4.2V.
The final mode is pulse charging or trickle charging where small pulses of current are passed to the battery to improve the life cycle of the battery.
There are also much more complex chargers involving 7-steps of charging.
We will not get much deep into this topic since it is far out of scope of this article.
But if you are interested in knowing mention on the comment section and may I will write a separate article on charging the Li-ion cells.
The state of charge is nothing but the capacity of the battery, similar to the ones shown in our mobile phone.
The capacity of a battery cannot be plainly calculated with its voltage valve, it is normally calculated using current integration to determine the change in battery capacity over time.
How far the battery can be discharged is given by the DOD.
No battery will have 100% discharges since as we know it will damage the battery.
Normally an 80% depth of discharge is set for all batteries.
Another unique and interesting feature of the 18650 cell is its dimension.
Every cell will have a dia of 18mm and a height of 650mm which makes this cell gets its name 18650.
, where you are sure to find more technical parameters related to a battery.
Easiest Way to Use an 18650 Cell
If you are a complete newbie and is just getting started with 18650 cells to power your project, then the easiest way would be to use readymade modules which can safely charge and discharge your 18650 cells.
Only such module is the TP4056 module which can handle a single 18650 cell.
If you project requires more than 3.6V as input voltage then you might want to combine two 18650 cells in series to obtain a voltage of 7.4V.
In such case use a module like 2S 3A Li-ion battery module should be useful in charging and discharging the batteries safely.
is used.
Also while combining 18650 cells in series or parallel more care should be taken which is discussed in the following paragraph.
Li-ion Battery Pack (cells in series and parallel)
To power small portable electronics or small devices a single 18650 cell or at most a pair of them in series would do the trick.
In this type of application the complexity is less since the number of batteries involved is less.
But for bigger application like a Electric Cycle/Moped or a Tesla cars we will need to connect a lot of these cells in series and parallel fashion to attain the desired output voltage and capacity.
For instance the Tesla car contains over 6800 lithium cells each of rating 3.7V and 3.1Ah.
The picture below shows how it is arranged inside the chassis of the car.
The job of the BMS is to monitor the individual cell voltage of every lithium ion cell and also check for its temperature.
Apart from that some BMS also monitors the charging and discharging current of the system.
Apart from this the designer also have to worry about cooling these batteries while charging and discharging since they don’t respond well during high temperatures.
Hope this article has provided you enough details for you to get a bit confident with Li-ion cells.
If you have any specific doubts feel free to leave the in the comment section and I will try my best in responding back.
Until then happy tinkering.
tutorial/frequency-compensation-of-op-amp
Frequency Compensation of Op-amp and why it is important in your Op-Amp Circuits
are very easy to implement for different purposes but it has few limitations that often leads to complexity.
across the operational amplifier.
The stability of an amplifier is highly dependent on different parameters.
In this article let’s understand the importance of Frequency Compensation and how to use it in your designs.
Quick Basics on Op-Amp
Before going straight into the advance application of operational amplifiers and how to stabilize the amplifier using frequency compensation technique, let's explore a few basic things about the operational amplifier.
amplifiers have the feedback circuitry connected across negative terminal.
Why do we need Frequency Compensation in Op-Amps?
configuration.
across the input and could provide a reasonable amount of current across the output.
Therefore, operational amplifiers can be driven using low signals to drive loads of higher current.
But what is the maximum current the op-amp could deliver to drive the load safely? The above circuit is good enough to drive pure resistive loads (ideal resistive load) but if we connect a capacitive load across the output, the op-amp will become unstable and based on the value of load capacitance at worst case the op-amp might even start to oscillate.
Let’s explore why the op-amp gets unstable when a capacitive load is connected across the output.
The above circuit can be described as a simple formula -
Acl= A / 1+A
, the feedback factor is 1 hence all of the output can be considered as going back to the input.
For the explanation of the A, let's draw the negative feedback amplifier in a different point of view.
The above image is a representation of the formula and negative feedback amplifier circuit.
It is exactly identical with the traditional negative amplifier stated previously.
They both share AC input on the positive terminal, and both have the same feedback in the negative terminal.
The circle is the summing junction has two inputs, one from the input signal and the second one from the feedback circuit.
Well, when the amplifier is working in negative feedback mode, the complete output voltage of the amplifier is flowing through the feedback line to the summing junction point.
At the summing junction, feedback voltage and the input voltage is added together and feeded back into the input of the amplifier.
because the op-amp showing A is a standalone open circuit, the feedback is not directly connected.
The output of the summing junction is further amplified by the op-amp open-loop gain.
Therefore, if this complete thing is represented as a mathematical formation, the output across the summing junction is -
Vin - Vout
Now the output of the amplifier will be -
Vout = open loop gain x (Vin - Vout)
Or,
Vout = A(Vin - Vout)
Vout = AVin - VoutA
Vout + VoutA= AVin
Vout (1+A) = AVin
Vout/Vin = A/(1+Aβ)
Instability Problem in Op-Amp
But the closed-loop gain is limited as the power supply which is connected across the op-amp is limited hence the Amplifier will become unstable.
Now, for a negative feedback amplifier, the phase shift of the input and output is 180 degrees.
When a capacitive load is connected across the amplifier, it can alter the phase by adding an additional pole across the op-amp output resulting in a negative to positive feedback conversion.
The loop gain gets 1 at the 180-degree phase shift and induces instability.
when switching the output state.
Since practically there are no ideal loads, resistive loads are not ideally resistive even perfectly made circuits have lots of capacitance as well as inductance.
The outcome is poor phase response at high frequency and instability.
How to deal with Op-Amp Instability?
This is a useful technique to overcome the instability of the op-amp as well as improve the step response of the circuit.
Types of Op-Amp Frequency Compensation
There are different types of frequency compensation techniques used in electronics.
However, all techniques are categorized into two basic types of compensation technique.
The first one is external compensation across the op-amp and the second one is the internal compensation technique.
External Frequency Compensation in Op Amp
Out of the loop compensation technique uses a simple resistor to isolate the capacitive load with the op-amp, lowering the capacitive loading of the op-amp.
The resistor typically varies from 10-50 Ohms but the increase in isolated resistor effects the op-amp bandwidth.
The bandwidth of the op-amp drastically reduced to a very low value.
One of the popular ways of out of the loop frequency compensation techniques is to use Dominant pole compensation technique.
is shown below.
This works great to overcome the instability issue.
The RC network creates a pole at unity or 0dB gain that dominates or cancels out other high-frequency poles effect.
The transfer function of the dominant pole configuration is ᾍ
Another effective compensation technique is the miller compensation technique and it is an in-loop compensation technique where a simple capacitor is used with or without load isolation resistor (Nulling resistor).
That means a capacitor is connected in the feedback loop to compensate the op-amp frequency response.
is shown below.
In this technique, a capacitor is connected to the feedback with a resistor across the output.
with inverting gain dependent on R1 and R2.
The R3 is the null resistor and the CL is the capacitive load across the op-amp output.
CF is the feedback capacitor which is used for the compensation purposes.
The Capacitor and the resistor value depend on the type of amplifier stages, pole compensation, and the capacitive load.
Internal Frequency Compensation Techniques
between the second stages Common emitter transistor.
For example, the below image is the internal diagram of popular op-amp LM358.
and as well as prevent the oscillation and ringing effect across the output.
Frequency Compensation of Op-amp ᾠPractical simulation
To understand Frequency compensation more practically let’s try to simulate it by considering the below circuit ᾍ
with a 100pF of capacitive load and will check how it will perform in low and high-frequency operation.
of the circuit.
But it is a bit tricky for the pspice since simulating the exact circuit, as shown above, will represent its closed-loop gain.
Therefore special considerations need to be taken.
The step to converting the above circuit for open-loop gain simulation (gain vs phase) in pspice is stated below,
The input is grounded to obtain the feedback response; closed-loop input to output is ignored.
Inverting input is broken into two parts.
One is the voltage divider and another one is the negative terminal of the op-amp.
Two parts are renamed to create two separate nodes and identification purposes during the simulation phase.
Voltage divider section is renamed as feedback and the negative terminal is renamed as Inv-input.
(Inverting input).
These two broken nodes are connected with a 0V DC voltage source.
This is done because, from the term of DC voltage, both nodes have same voltage which is essential for the circuit to satisfy the current operating point requirement.
Adding the voltage source with a 1V of the AC stimulus.
This forces the two individual nodes voltage difference to become 1 during the AC analysis.
One thing is essential in this case, that the ratio of the feedback and the inverting input is dependable on the circuits open-loop gain.
After making the above steps, the circuit looks like this -
The circuit is powered using 15V +/- power supply rail.
Let's simulate the circuit and check its output bode plot.
Since the circuit has no frequency compensation, as expected the simulation is showing high gain at low frequency and low gain at high frequency.
Also, it is showing very poor phase margin.
Let's see what is the phase at 0dB gain.
As you can see even at 0dB gain or unity gain crossover, the op-amp is providing 6 degrees of phase shift at just only 100pF capacitive load.
across the op-amp and analyze the result.
A 50 Ohms of null resistor is placed across the op-amp and the output with a 100pF compensation capacitor.
The simulation is done and the curve looks like the below,
The Phase curve is much better now.
The phase shift at 0dB gain is almost 45.5 degrees.
The amplifier stability is highly increased using the frequency compensation technique.
Therefore, it is proven that the frequency compensation technique is highly recommended for the better stability of the op-map.
But the Bandwidth will decrease.
and how to use it in our Op-Amp designs to avoid instability problems.
Hope you enjoyed reading the tutorial and learnt something useful.
If you have any questions leave them in our forums or in the comment section below.
article/what-is-solenoid-its-working-principle-and-types
An Introduction to Solenoids
What is a Solenoid?
is a long piece of wire which is wound in the shape of a coil.
When the electric current passes through the coil it creates a relatively uniform magnetic field inside the coil.
or as a miniature wireless receiving antenna in a circuit.
Solenoid Working Principle
Most of the flux is concentrated only on the core, while some of the flux appears at the ends of the coil and a small amount of flux appears outside the coil.
can be increased by increasing the density of the turns or by increasing the current flow in the coil.
Like all other magnets the activated solenoid has both Positive and Negative poles, through which an object can be attracted or repelled.
Types of Solenoids
There are different types of solenoids available in the market, the classification is made based on material, Design and function.
AC- Laminated Solenoid
DC- C Frame Solenoid
DC- D Frame Solenoid
Linear Solenoid
Rotary Solenoid
The AC laminated Solenoid consist of a metal core and a coil of wire.
The core is constructed with a laminated metal in order to reduce the stray current, this helps in improving the performance of the solenoid.
(An instantaneous high inputcurrentdrawn by a power supply or electrical equipment when turn-on).
They are capable of using more strokes than a DC laminated solenoid.
They are available in different configurations and ranges and they produce a clean buzzing sound when they are in operation.
in a variety of equipments that require immediate action, such as medical equipments, locks, vehicles, industrial equipments, printers, and in some of the household Appliances.
The C frame refers to the design of the solenoid.
The DC C-Frame solenoid has only a frame in the shape of the letter C which is covered around the coil.
in gaming machines, Photographic shutters, Scanners, Circuit breakers, Coin counters and Bill changers.
This type of solenoid has a two piece frame covering the coils.
They have similar function like a C-frame solenoid hence the D-frame can also be used with AC power and has a controlled stroke operation.
for both conventional and medical applications such as gaming machines, ATM machines and Blood and gas Analyzer.
The linear solenoids are more familiar among the people.
It consist of a coil of wire which is wrapped around a movable metal core which helps us to apply pulling or pushing force to a mechanical device.
This type of solenoids is mostly used on starting devices.
This switching mechanism helps in completing a circuit and allows the current to flow thorough a mechanism.
in the automation and Highly secured door mechanisms and starter motors of cars & bikes.
A rotary solenoid is a unique type of solenoid which is used for various applications where there is a need for easy automatic control process.
It works on the same principle as the other solenoids and has the same elements, a coil and a core, but they have a different operation.
The metal core is mounted to a disk and has small grooves under it, The size of the grooves exactly matches with the slots in the body of the solenoid.
It also has ball bearings to make easy motion.
When the solenoid gets triggered the core is drawn into the body of the solenoid and the disc core start rotating.
This setup will have a spring place in between the core and the body of the solenoid.
Once the power supply is detached the spring pushes the disk core to its original position.
when compared to all other types of solenoids.
They were originally designed only for the defence mechanisms, but nowadays you will be able to find them in many automated industrial mechanisms such as laser and shutter.
Conclusion
available in the market.
The solenoids are the simple and effective solution for controlling the valves and electromagnetic switches or mechanical interlocks.
Their operation principle and instantaneous response made them a better solution for applications that needs a large amount of power into a small space and where there is a need of quick, consistent and robust operation.
along with its driver circuit:
Solenoid Driver CircuitHow to control a Solenoid Valve with ArduinoAutomatic Water Dispenser using Arduino
Now you know everything about the solenoid, so, you can start implementing the knowledge with your creativity to take advantage of the properties of solenoid to create your next invention.
article/understanding-intellectual-property-and-patents-and-how-to-patent-a-design
Understanding Intellectual Property & Patents and How to Patent a Design
written on the goods, products or devices that we buy.
Have you ever tried to dig deeper into the meaning of these terms, ever thought why the manufacturer or maker of the product is mentioning it, what is its sole purpose?
Why should I get a Patent?
are also being sold in the market, these products are not only eating your profits but are also affecting your brand image with their cheap built quality, now what can you do to save your product and unfair competition? If you go to any government body for the help you have to prove them you are the original manufacturer of the product, it’s your creation and you have your rights on it and the twisted part of the story is you can’t prove them, you don’t have any rock-solid proof or any legal proof which can show your ownership over it and then you and your product are doomed.
and provide the strongest form of protection among all other members of the intellectual property family.
Intellectual property is a form of intangible assets that provides protection over the creation of the intellect (mind) which includes artistic creations, symbols, and images, names used in businesses and new innovation and inventions.
An individual, a group of individuals or an organization can be the owner of the intellectual property which provides them with the intellectual property rights, which gives an exclusive right to an individual or an organization over the creation for a limited period of time without the fear of the unfair competition.
Types of Intellectual Property
There are various forms of Intellectual Property (IP) and all of them provide different type of protections whenever one launches a product; they need to utilize one of the intellectual properties before commencing the marketing activities.
The most common types of IP are Patents, Trademarks, Copyrights and Trade secrets.
Protects the utility, functional features Strongest form of IP protection available E.g.
Working of a wireless router
Protects brand names, phrases, logos, symbols.
Used by manufacturers or merchant to identify goods and to distinguish them from others.
E.g.
Burger king
Protects the creative works of author, designer, maker etc.
E.g.
Lion king movie
Protects the secret information related to a process etc.
E.g.
Formula of Coca-Cola
and in return of the public release of his invention, he gets an exclusive right to it for a limited period of time, and that period of time depends upon the type of patent.
or one can say the standards on which patent is granted is that the invention should be new (novel), non-obvious (to the person having ordinary skill in the art), should have some practical applicability (useful) and must fall under the category of eligible subject matter which includes machines, manufactured articles, industrial processes and chemical composition.
Further, there are three types of patents in broad with a different lifetime, here the lifetime denotes the time under which the patent is solely and exclusively owned by the subject inventor or organization.
Type of Patents
Utility patent ᾠUtility patent is one of the most common types of patent that people seek.
Utility patents cover new and useful processes, methods, materials and novel compositions.
Improvements and changes in previous inventions to bring out the most effective way is also a big part of this.
These patents have a lifetime of 20 years.
Design patent or Industrial designs ᾠDesign patents or the Industrial designs cover the ornamental shape, appearance and the aesthetic sense of the product.
Further, it can’t be obtained for ornamental features that are not visible when the product is in use.
It doesn’t demonstrate any functionality of a given device but is just a 2D or a 3D sketch of a product.
Life of Design patent and industrial Design varies from 10 to 15 years.
Plant patent ᾠPlant patent protects the category of new and distinctive plants.
The few of the conditions to get the plat patent includes that it should be asexually reproduced.
Here the asexually reproduced means it should be produced by the techniques like grafting or cutting instead of using the seeds, this requirement is kept so as to be sure that owner of the patent can reproduce the plant.
There are certain misconceptions among people related to the patenting system and one of it includes that one can obtain a patent on any idea, technically it’s not true.
Idea’s alone can’t be patented.
One can only obtain a patent on the invention developed from an idea and the description of how it works must be included with the patent application.
Why it’s important to protect your Intellectual Property
then it can make a blow to his business, if a competitor brings out a similar product.
If one launches a popular product that is hitting the market, then obviously someone will come out with a competitive product.
As a maker, an engineer, a designer one has to realize what is new and unique about the creation and make sure to get appropriate protection.
Moreover, IP assets generate money for an organization if they are well maintained, one can sell or license their assets and these deals happens in large financial figures.
if one is not going to get profit from it.
Before making a monetary investment in patenting an invention filter the target market and ask is this something that people will buy.
If one knows his target market he can strategically account for the manufacturing cost and retail price by comparing similar products available, this will also help in knowing the competition, what they are selling and how you can monetize over the void between your products to that of your competitor.
Patenting an Electronic Product Design and its Worth
or registered design.
and it’s related to the products like bracelets, rings and necklace and it becomes really important to protect its ornamental look.
To some people design patent looks a bit confusing by mismatching it with the utility patent.
Design patent is obtained on the aesthetic look and appearance of a product.
A particular shape of an automobile, a bottle, or a cycle has to covered under the design patent.
You can’t obtain a utility patent on these products because of existing prior arts.
Design patents are much easier to obtain but one can overcome them easily with certain design changes in the existing product.
and its design is helping in increasing the illumination spread, one can go for the utility patent for protecting its functionality and design patent for protecting its design.
How can you improve your Patent Application?
If you have decided that you have to go with the patent for protecting your intellectual property, then do extensive research on your product/invention.
Start with making a prototype or a working model of it.
Since a patent application includes all the details of the product/invention a prototype could really help in realizing all those points of your invention.
This would also help in making design changes to increase the efficiency and this could really contribute to the novelty aspect of the invention.
Take the help of existing prior arts both (patent literature & non-patent literature) by reporting them in a prior art search report.
You could really take help of a professional patent researcher for reporting them for you by reporting the nearest prior arts available worldwide.
If you know the broader aspect of your technology but don’t know what to innovate in it or what to research on? Then you can really take the help of landscape research by a patent professional.
A landscape research report includes an extensive search on technology by creating taxonomy of its various aspects and then reporting the patents into different fields which helps you to get a brief idea how technology is growing, which parts of it are being extensively researched and which development is taking place.
The graphical analysis provides a 360-degree view of a particular technology.
If one is interested in seeing where to innovate in a particular technology than he should go for the white space analysis.
It gives a void area analysis of the grey areas where the innovation in a particular technology is less and makes a way out for inventor.
Always prefer to get a brief reporting of the results from a professional.
For any further help or information, you can contact me.
Design patents, Registered Designs and their Lifetime
as “registered designᾮ While in the other countries designs are protected under patent law as “design patentsᾮ
and can be further extended up to 5 years by renewing it but that also depends upon country to country.
Why people hesitate to file a Design Patent
A fun fact is that the design patents are cheaper to obtain than the utility patent but there are more utility patents available than the design patents.
The reason is that many people and companies hesitate to obtain design patents.
The following reasons could be possible for it.
Intellectual property has a simple rule; less price means less protection.
Since design patents are much cheaper to obtain they offer lesser protection since they can be easily overcome by significant design changes to make the new design look unobvious.
In rapidly changing industries such as smart bands or mobiles whose product design changes really fast it becomes an unfruitful task to obtain design protection.
Since, prior to publishing or issuing (US design patent), a design(product) can’t be in the public domain.
Further, the lifetime of a design patent is really short so people usually try to get some other type of protections such as copyrights for their designs.
In geographies like the US, design patent applications are not published.
A design patent when issued then only comes in public domain.
So it becomes really hard for third parties to keep an eye on the design patent application of others.
Apple V/S Samsung Case - A Billion-Dollar Patent Infringement Case study
most of the time is less effective than the utility protection as it can easily be overcome by adopting a slightly different design.
Though the protection may vary in different kinds of IP but the legal battles which are fought on its ground are really costly.
had a chance to foresee each other in trademark infringement.
in 2011 which ended up in 2018 and involved the multiple infringements which also included design infringements.
Let’s understand this case and the importance of Intellectual property for a business with the help of Evidence of Use (EOU’s) charts of few design patent infringements.
Fascinate.
The infringement involved the features such as the position of the speaker slots, Upper and bottom surfaces of the screen covered with black borders.
The charting above shows the Apple patents against Samsung’s galaxy S2.
, titled as “Electronic Deviceᾮ The infringement involved around Eight Samsung devices are accused to infringe upon Apple’s patent, the devices included the Galaxy S2, the T-Mobile Vibrant, and the Infuse 4G.
The features which were the reason for infringing were the Home button at bottom of the screen, Border on all sides with equal width, and rectangular body with rounded corners.
, titled as Graphical user interface for a display screen or portion thereof, which involved the infringement over the Graphical User Interface (GUI’s) between the Apple patents and thirteen of accused Samsung devices including the US variants of the Galaxy S2, the Droid Charge, and the Infuse 4G.
The infringement involved an interface of colorful square icons with uniformly rounded corners and the second features involved a bottom row of square icons set that doesn’t change as the other pages of the interface are viewed.
Only solid lines are from the claimed design, dotted lines are just for the part of the reference.
Conclusion
Though many other companies like Google came into the picture as the case proceeded but they were not totally into the suit as the Apple’s arguments were against the hardware companies which were directly getting the benefits from their IP not with a software company which was freely distributing the operating system for the products.
Apple V/S Samsung Suit clearly shows the importance of IP including patents, designs etc.
It becomes really important to protect your innovation when stepping out for business.
article/what-is-vacuum-tube-and-how-does-it-work
What is Vacuum Tube and How does it Work
You might be tempted to dismiss the good old tube as a relic of the past ᾠafter all, how can a few pieces of metal in a glorified light bulb hold up to the transistors and integrated circuits of today? Although tubes lost their place in the storefront of consumer electronics but they still remain insignificant use where there is need for a lot of power at very high (GHz range) frequencies, such as in radio and television broadcasting, industrial heating, microwave ovens, satellite communications, particle accelerators, radar, electromagnetic weapons plus a few applications requiring lower power levels and frequencies, such as radiation meters, X-ray machines and audiophile amplifiers.
, mixers etc.
are easier to explain with tubes and see how they work, because classic tubes, especially triodes, are extremely easy to bias with few components and calculate their amplification factor, bias etc.
How Vacuum Tubes Work?
Imagine that it’s a hot summer day you are waiting in line in a stuffy room, next to a wall with a heater along the length of it, some other people are waiting in line too and someone turns on heating, people start moving away from the heater ᾠthen someone opens the window and lets a cold breeze in, causing everyone to migrate to it.
When thermionic emission occurs in a vacuum tube, the wall with the heater is the cathode, heated by a filament, the people are the electrons and the window is the anode.
In most vacuum tubes the cylindrical cathode is heated by a filament (not too different from the one in a light bulb), causing the cathode to emit negative electrons that are attracted by a positively charged anode, causing an electric current to flow into the anode and out of the cathode (remember, current goes into the opposite direction than electrons).
etc
In the beginning there were Diodes
Nothing like the good old Triode!
In 1906 an American Engineer called Lee de Forest discovered that adding a grid, called a control grid, between the anode and the cathode allows for the anode current to be controlled.
Triode’s construction is similar to the diode, with the grid being made from very fine mobyldenium wire.
The control is achieved by biasing the grid with a voltage ᾠthe voltage usually being negative in respect to the cathode.
The more the voltage is negative, the lower the current.
When the grid is negative it repels electrons, decreasing the anode current, if it is positive more anode current flows, at a cost of the grid becoming a tiny anode, causing grid current to form which might damage the tube.
Triode and other “griddedᾠtubes are usually biased by connecting a high value resistor between grid and ground, and a lower value resistor between the cathode and ground.
The current flowing through the tube causes a voltage drop on the cathode resistor, increasing the cathode voltage in respect to ground.
The grid is negative in respect to the cathode, because the cathode is at a higher potential than the ground to which the grid is connected to.
, with the triode part varying its resistance in accordance to the input signal’s voltage.
Tetrodes to the rescue!
Early triode suffered from low gain and high parasitic capacitances.
In the 1920s it was found that putting a second (screen) grid between the first one and the anode, increased the gain and lowered parasitic capacitances, the new tube was named tetrode, meaning in Greek four (tetra) way (ode, suffix).
The new tetrode wasn’t perfect, it suffered from negative resistance caused by secondary emission that could cause parasitic oscillations.
Secondary emission occurred when the second grid voltage was higher than the anode voltage, causing a decline in anode current with the electrons hitting the anode and knocking out other electrons and the electrons being attracted by the positive screen grid, causing an additional possibly damaging increase in grid current.
Pentodes ᾠthe final frontier?
Research in ways of reducing secondary emission resulted in the invention of the pentode in 1926 by the Dutch engineers Bernhard D.H.
Tellegen and Gilles Holst.
It was found that adding a third grid, called a suppressor grid, between the screen grid and the anode, removes the effects of secondary emission by repelling electrons knocked out of the anode back to the anode since it is either connected to ground or to the cathode.
Today pentodes are used in transmitters below 50MHz, as tetrodes in transmitters work good up to 500MHz and triodes up to the gigahertz range, not to mention audiophile use.
Different Types of Vacuum Tubes
Apart from these “regularᾠtubes there is a lot of specialized industrial and commercial tubes designed for different uses.
is similar to the diode, but with resonant cavities shaped into the tube’s anode and the whole tube located between two powerful magnets.
When voltage is applied, the tube starts oscillation, the electrons passing the cavities on the anode, causing generation of radio frequency signals, in a process similar to whistling.
X-ray tubes are used to generate X-rays for medical or research purposes.
When a high enough voltage is applied to the vacuum tube diode X-rays are be emitted, the higher the voltage the shorter the wavelength.
To deal with heating of the anode, caused by electrons hitting it, the disc-shaped anode rotates, so the electrons hit different parts of the anode during its rotation, improving cooling.
After passing the anodes they pass the deflection plates and impact the fluorescent front of the tube, causing a bright spot to appear where the beam hits.
The deflection plates are used to scan the beam across the screen by attracting and repelling electrons in their direction, there are two pairs of them, one for the X-axis and one for the Y-axis.
A small CRT made for oscilloscopes, you can clearly see (from the left) the Wehnelt cylinder, the circular anodes and the deflection plates in the shape of the letter Y.
Traveling-wave tubes are used as RF power amplifiers on board communication satellites and other spacecraft due to their small size, low weight and efficiency at high frequencies.
Just like the CRT it has an electron gun in the back.
A coil called a “helixᾠis wound around the electron beam, the input of the tube is connected to the end of the helix closer to the electron gun and the output is taken from the other end.
The radio wave flowing through the helix interacts with the electron beam, slowing and speeding it up in different points, causing amplification.
The helix is surrounded by beam focusing magnets and a attenuator in the middle, it’s purpose is to prevent the amplified signal from getting back to the input and causing parasitic oscillations.
At the end of the tube a collector is located, it being comparable to the anode of a triode or pentode but no output is taken from it, is located.
The electron beam impacts the collector, ending it’s story inside the tube.
Geiger–Müller tubes are used in radiation meters, they consist of a metal cylinder (cathode) with a hole on one end and a copper wire in the middle (anode) inside a glass envelope filled with a special gas.
Whenever a particle passes through the hole and impacts the wall of the cathode for a brief moment the gas in the tube ionises, allowing current to flow.
This impulse can be heard on the meter’s speaker as a characteristic click!
article/what-is-ldo-low-dropout-voltage-regulator-and-its-significance-in-battery-operated-devices
Understanding Low-Dropout Voltage Regulators (LDO) and its significance in Battery Operated Devices
In this article we will learn more about LDO and how to select the right one for your circuit design.
What is a Regulator in electronics?
are used to controlling the voltage.
Difference between LDO and Linear Regulators
Therefore, standard linear regulators have some limitations when the regulated output voltage is required to be a close value of the input voltage.
Working of an LDO
Since the LDO has very low dropout voltage it is called as Low dropout voltage regulators.
You can think of a LDO’s an a linear resistor palced in series with the load to reduce the voltage to required level.
The advandage of a having an LDO is that the voltage drop across it will be far less than a resistor.
Since the LDO offers low dropout voltage between input and output, it can work even if the input voltage is relatively close to the output voltage.
The voltage drop across an LDO will be between 300mV to 1.5V maximum.
In some LDOs, the voltage differences are even less than 300mV.
are not used in LDOs due to the extra requirements of current and heat generation which leads to poor efficiency.
Parameters to consider while selecting your LDO
of an LDO ranges from 5mV to 50mV range, a few percentages of the output voltage.
and thermal protection.
In some situations, the input voltage provided to the regulator might drop significantly low or increase to high value.
This results in improper voltage and current output from the LDO which will damage our load.
If the input voltage across the LDO is beyond the limits, the UVLO and OVLO protection are triggered to protect the LDO and the load.
The lower limit for UVLO and the maximum input voltage limits can be set using simple voltage dividers.
works when the LDO gets heated.
During heat-up operation, the thermal protection circuit stops the LDO from working to prevent any further damage to it.
often referred to as EN and this is an input pin of the LDO.
A simple microcontroller can change the state of EN pin of an LDO to enable or disable the power output.
This is a handy feature when loads need to be turned on or off for application purposes.
is an output pin from the LDO.
This pin can also be connected with a microcontroller unit to provide a logic low or high depending on the power condition.
Based on the state of power good pin, microcontroller unit can get the information about the power status across the LDO.
Limitations of LDO
are still the best choice over linear regulators especially LDOs.
Should I use LDO for my next design?
As LDOs offer very low dropout voltage, it is good to select an LDO only when the desired output voltage is very close to the available input voltage.
Below questions can help you determine if you circuit design actually needs an LDO
Is the desired output voltage is close to the available input voltage? If yes, then how much? It is good to use LDO if the difference between Input voltage and output voltage is less than 300mV
Is 50-60% of efficiency is accepted for the desired application?
Low noise power supply is a need?
If the cost is a problem and simple, lower part count, the space-saving solution is needed.
Will it be too expensive and bulky to add a switching circuit?
If you have answered “YESᾠfor all the above question, then LDO might be a good choice.
But, what will be the specification of the LDO? Well, it depends on the below parameters.
Output Voltage.
Minimum and Maximum Input voltage.
Output current.
Package of the LDOs.
The cost and availability.
Enable and Disable option is required or not.
Additional protection options those are required for the application.
Such as Over current protection, UVLO, and OVLO, etc.
Popular LDOs in the market
has wide range of LDOs depending on various design needs, the below chart shows its huge collection of LDO with a wide range of output current and input voltage.
LDO ᾠExample Design
A lithium battery can provide 4.2V during full charge condition and 3.2V on fully empty condition.
Therefore, the LDO can be controlled to disconnect the load at low voltage situation by sensing the input voltage of the LDO by the microcontroller unit.
- 3.3V fixed voltage regulator by microchip.
The full feature list can be seen in the below image, taken from the datasheet -
along with the pin-out.
The schematic is also provided in the datasheet, thus by simply connecting few external components like resistor and capacitor we can easily use our LDO to regulate out required voltage with minimum voltage dorp.
LDO - PCB design guidelines
Once you have deicided the LDO and tested it to work for your design, you can proceed with designing the PCB for your circuit.
The following are the few tips you should remember while designing a PCB for LDO components.
If SMD package is used, it is essential to provide a proper copper area in PCBs since LDOs dissipate heats.
Copper thickness is a major contributor to trouble-free operation.
2 Oz (70um) copper thickness will be a good choice.
C1 and C2 need to be as close as possible to the MCP1825.
The thick ground plane is required for noise-related issues.
Use Vias for proper heat dissipation in double-sided PCBs.
article/basics-of-smith-chart-and-how-to-use-if-for-impedance-matching
Basics of Smith Charts and how to use it for Impedance Matching
We will look into the types of smith chart, its construction and how to make sense of the data it holds.
What is a Smith Chart?
of the complex reflection coefficient for arbitrary impedance.
with the alternative being tabulating the information.
and simple impedance measuring instruments include smith charts in the display options which makes it an important topic for RF Engineers.
Types of Smith Charts
or both, using different colours to distinguish between them and serving as a means to categorize them into different types.
Based on this scaling, smith charts can be categorized into three different types;
The Impedance Smith Chart (Z Charts)
The Admittance Smith Chart (YCharts)
The Immittance Smith Chart.
(YZ Charts)
are the most popular and the others rarely get a mention, they all have their “superpowersᾠand can be extremely useful when used interchangeably.
To go over them one after the other;
which are usually the main elements in impedance matching and other related RF engineering tasks.
They are the most popular, with all references to smith charts usually pointing to them and others being regarded as derivatives.
The image below shows an impedance smith chart.
The focus of today’s article will be on them so more details will be provided as the article proceeds.
as such, an admittance chart makes sense for the complex parallel situation as all you will need to do is to examine the admittance of the antenna rather than the impedance and just add them up.
An equation to establish the relationship between admittance and impedance is shown below.
YL = 1 / ZL = C + iS …‐)
True to their relationship described by the relationship above, the admittance smith chart possesses an inverse orientation to the Impedance smith chart.
The image below shows the admittance Smith Chart.
in the setup.
To solve this, the immittance smith chart is used.
Its a literally effective solution to the problem as it is formed by superimposing both the Impedance and Admittance smith charts on one another.
The picture below shows a typical Immittance Smith Chart.
It is as useful as combining the ability of both the admittance and impedance smith charts can be.
In Impedance matching activities, it helps identify how a parallel or series component affects the impedance with less effort.
Smith Chart Basics
and as such, is more often than not, a complex number, as a result of this, the reflection coefficient is also a complex number, since it is completely determined by the impedance ZL and the "reference" impedance Z0.
Based on this, the reflection coefficient can be obtained by the equation;
Where Zo is the impedance of the transmitter (or whatever is delivering power to the antenna) while ZL is the impedance of the load.
as a function of frequency, either as a single point or a range of points.
Components of a Smith Chart
A typical smith chart is scary to look at with lines going here and there but it becomes easier to appreciate it once you understand what each line represents.
Impedance Smith Chart
Impedance Smith Chart contains two major elements which are the two circles/arcs which define the shape and data represented by the Smith Chart.
These circles are known as;
The Constant R Circles
The Constant X Circles
all tangent to each other at the right hand of horizontal diameter.
The constant R Circles are essentially what you get when the Resistance part of the Impedance is held constant, while the value of X varies.
As such, all the points on a particular Constant R circle represent the same resistance value(Fixed Resistance) .
The value of the resistance represented by each Constant R Circle is marked on the horizontal line, at the point where the circle intersects with it.
It is usually given by the diameter of the circle.
For example, consider a normalized impedance, ZL = R + iX, If R was equal to one and X was equal to any real number such that, ZL = 1 +i0, ZL = 1 +i3, and ZL = 1 +i4, a plot of the impedance on the smith chart will look like the image below.
Plotting multiple constant R Circles gives an image similar to the one below.
This should give you an idea of how the giant circles in the smith chart is generated.
The Innermost and Outermost Constant R Circles, represent the boundaries of the smith chart.
The Innermost Circle(black) is referred to as the infinite resistance, while the outermost circle is referred to as the zero resistance.
The lines in the upper half represent positive reactances while those in the lower half represent negative reactances.
For example, let us consider a curve defined by ZL = R + iY, if Y = 1 and held constant while R representing a real number, is varied from 0 to infinity is plotted(blue line) on the Constant R Circles generated above, a plot similar to the one in the image below is obtained.
Plotting multiple values of ZL for both the curves, we get a smith chart similar to the one in the image below.
Thus, a complete Smith Chart is obtained by when these two circles described above are superimposed on one another.
Admittance Smith Chart
circle.
Note that the admittance Smith Chart will still plot the reflection coefficient but the direction and location of the graph will be opposite to that of the Impedance smith chart as mathematically established in the equation below
…‐)
To better explain this, let’s consider the normalized admittance Yl = G + i*S G = 4(Constant) and S is any real number.
Creating the constant conductance plot of the smith using equation 3 above to obtain the reflection coefficient and plotting for different values of S, we get the smith chart shown below.
The same thing holds for the Constant Succeptance Curve.
If the variable S = 4(Constant) and G is a real number, a plot of the Constant susceptance curve(red) superimposed on the Constant Conductance curve will look like the image below.
Thus, the Admittance Smith Chart will be an inverse of the Impedance smith chart.
The Smith chart also has circumferential scaling in wavelengths and degrees.
The wavelength scale is used in distributed component problems and represents the distance measured along the transmission line connected between the generator or source and the load to the point under consideration.
The degrees scale represents the angle of the voltage reflection coefficient at that point.
Applications of Smith Charts
Smith charts find applications in all areas of RF Engineering.
Some of the most popular application includes;
Impedance calculations on any transmission line, on any load.
Admittance calculations on any transmission line, on any load.
Calculation of the length of a short circuited piece of transmission line to provide a required capacitive or inductive reactance.
Impedance matching.
Determining VSWR among others.
How to use Smith Charts for Impedance matching
, both of which are natural pre-requisite for RF engineering.
As an example of how smith charts, are used, we will look at one of it’s most popular use cases which is impedance matching for antennas and transmission lines.
(capacitor or inductor) to use to ensure the line is perfectly matched, that is, ensuring the reflection coefficient is zero.
For example, Let’s assume an impedance of Z = 0.5 - 0.6j.
The first task to do will be to find the 0.5 constant resistance circle on the smith chart.
Since the impedance has a negative complex value, implieing a capacitive impedance, you will need to move counter-clockwise along the 0.5 resistance circle to find the point where it hits the -0.6 constant reactance arc (if it were a positive complex value, it would represent an inductor and you would move clockwise).This then gives an idea of the value of the components to use to match the load to the line.
(admittance).
Reflection coefficients can be read directly from the chart as they are unit-less parameters.
Also, the value of impedances and admittances change with frequency and the complexity of problems involving them increases with frequency.
Smith charts can however be used to solve these problems, one frequency at a time or over multiple frequencies.
(connecting several points) rather than a single point, provided the frequencies are close.
covering a range of frequencies on the smith chart can be used to visually represent:
How capacitive or inductive a Load is across the examined frequency range
How difficult matching is likely to be at the various frequencies
How well-matched a particular component is.
The accuracy of the Smith chart is reduced for problems involving a large locus of impedances or admittances, although the scaling can be magnified for individual areas to accommodate these.
The Smith chart may also be used for lumped element matching and analysis problems.
article/what-is-power-line-communication-plc-and-how-does-it-work
What is Power Line Communication (PLC) and How it works
Using PLC communication signals, high-speed data, voice and video are transmitted over low-voltage power lines.
and Smart Grids.
What is Power Line Communication?
which are already in use for the transmission of electric power using a modular signal.
Now, this can be done through the home or premises wiring and may also be done through the existing electric power distribution system.
is also known as power-line Internet which supports PLC technology to allow Internet access through the transmission lines.
The BPL technology with PLC is often used in remote locations where there is low amount of Internet access by cable or PDSL connections.
Types of Power Line Communication (PLC)
Basically, there are four types of PLC:
In-house networking: High-speed data transmission can be provided for home networking using the In-House mains power wiring.
Broadband over Power Line: Broadband internet access can be offered through the outdoor mains power wiring.
Narrowband in-house applications: Low bit rate data services like home automation and intercoms can be controlled and used for communication through the In-house power mains.
Narrowband outdoor applications: Narrowband outdoor applications can be used for automatic meter reading and remote surveillance or control.
How does PLC Work?
Like any other communication technology PLC also consists of a sender who modulates the data that is to be sent through a communication medium, and then the receiver will demodulate the data for further use.
Apart from sending the signals for communication, PLC also allows the user to control and monitor all the connected devices to the power line because it is implemented in the same wiring system.
and frequency generator for getting as stable as possible output of desired frequency but there was a small fluctuation in the output whereas the PLC system uses a Rectifier with a Filter & a Microcontroller which provides a stable & desired value output with the help of relay switch.
As a result, the transmission of data is more accurate & more stable with good output signals.
Modulation Schemes used in PLC:
The modulation schemes used in PLC are Orthogonal Frequency Division Multiplexing (OFDM), Binary Phase Shift Keying (BPSK), Frequency Shift Keying (FSK), Spread-FSK (S-FSK) and proprietary schemes too (like the Differential Code Shift Keying (DCSK)).
that can handle such a heavy computation.
Uses of PLC
The PLC is used for transmitting radio programs, utility company control switching mechanisms, transmission line protection, and automatic meter reading.
Apart from that, there are also some automotive uses where the data, voice, and music are sent over direct current (DC) battery power line with some special filters to remove the line noise from the final output.
The term Power Line Communication (PLC) is known with a various name like as power line carrier, power-line digital subscriber line (PDSL), power line telecom (PLT), power line networking (PLN), mains communication, and broadband over power lines (BPL).
Advantages and Disadvantages of PLC
Low Implementation Cost: PLC does not require any installation of new wires which as a result, would significantly reduce the deployment costs.
Large Reach: PLC can enable communication with hard-to-reach nodes where the RF wireless signal suffers from high levels of attenuation like in the underground structures or the buildings with obstructions and metal walls, or simply wherever the wireless signal is undesirable due to the EMI issues in places like hospitals.
Lower Running Cost: PLC provides a low-cost solution compared to the other existing technologies such as RF wireless or visible light communication (VLC) systems.
Indoor High Speed: The implementation of PLC & VLC technologies integrated together has recently received a considerable amount of research attention, which resulted in the enabling of a new generation of high-speed indoor communications for numerous applications.
These advantages lead to more implementations of PLC networks in various industries.
But with advantages there also comes some disadvantages.
It also has some disadvantages such as:
Lowtransmission speed,
Sensitivity to disturbance,
Nonlinear distortion and Cross-modulation between channels,
Large size and
The high price of capacitors andinductorsused in the PLC system.
Due to these disadvantages, PLC is still not preferred in some applications.
Applications of PLC
PLC is widely used in technologies like Smart Grid and micro-inverters.
Getting the technologies familiar with more number of users, soon PLC will have more adaptation for applications like lighting applications (for traffic light control, LED dimming etc.), industrial applications (for irrigation control etc.), machine-to-machine applications (like for vending machines or a hotel’s reception-to-room communication), telemetry applications (e.g.
offshore oil rigs), transport applications (like for electronics in cars, trains, and airplanes) and many more.
Problems faced by PLC
The main biggest problem that the PLC is facing till date is that the power wiring in the PLC technology is unshielded and untwisted which means that the wiring will emit large amounts of radio energy, which as a result, will cause interference to the existing users of the same frequency band.
Also, the BPL (Broadband over Power Line) systems will get some interference from the radio signals emitted by the PLC wirings.
article/how-optical-fiber-communication-works-and-why-it-is-used-in-high-speed-communication
How Optical Fiber Communication works and why it is used in High Speed Communication
is the method of communication in which signal is transmitted in the form of light and optical fiber is used as a medium of transmitting those light signal from one place to another.
The signal transmitted in optical fiber is converted from the electrical signal into light and at the receiving end, it is converted back into the electrical signal from the light.
The data sent can be in the form of audio, video or telemetry data that is to be sent over long distances or over Local Area Networks.
Optical fiber communication having good results in long-distance data transfer at high speed, it has been used as an application for various communication purposes.
How do Fiber Optic Communication works?
transmits a signal in the form of light which is first converted into the light from electrical signals and transmitted, and then vice versa happens on the receiving side.
This process can be explained using a diagram as shown below:
And if the input is digital then it is directly sent through the light source transmitter circuit which converts the signal in the form of light waves.
The light waves received from the transmitter circuit to the fiber optic cable is now transmitted from the source location to the destination and received at the receiver block.
, also known as the light detector, receives the light waves from the optical fiber cable, amplifies it using the amplifier and converts it into the proper digital signal.
Now if the output source is digital then the signal is not changed further and if the output source needs analog signal then the digital pulses are then converted back to an analog signal using the decoder circuit.
Why Fiber is used?
The fiber wires have replaced the copper wire as transmission cable since it has more advantages than the electrical cables.
Large Transmission capacity: A singlesilica fibercan carry hundreds of thousands of telephone channels, utilizing only a small part of the theoretical capacity.
Small Losses: Approximately 0.2dB/km signal is lost for modernsingle-modesilica fibers so that many tens of kilometers can be bridged withoutamplifyingthe signals.
Easy Amplification: A large number of channels can be reamplified in a singlefiber amplifier if required for very large transmission distances.
Low Cost: Due to the huge transmission rate achievable, the cost per transported bit can be extremely low.
LightWeight: Compared with electrical cables,fiber-optic cablesare very lightweight.
No Interference: Fiber-optic cables are immune to problems that arise with electrical cables, such as ground loops or electromagnetic interference (EMI).
and this is why Fiber optic cables are preferred over the conventions transmission mediums.
Why light and not Electricity?
While the other light signals like sunlight or bulb light have many wavelengths of light and as a result, if used for communication they would produce a beam which is very less powerful and on the other hand, the laser having a single beam would result in a more powerful beam as output.
makes the light a good source for communication.
Characteristics of Fibre Optic Communication
In Optical fiber communication, light is used as a signal which transmitted inside the optical fiber cable.
This mode of communication has characteristics which are important to be discussed and makes it a good mode of communication.
Bandwidth ᾠSingle laser light dispersion means that a good amount of signal can be transmitted (Information being transferred in bits) per second which results in high bandwidth for long distances.
Smaller diameter ᾠThe diameter of Optical fiber cable is about 300 micrometers in diameter.
Light-weight ᾠThe Optical fiber cable is light in weight compared to the copper cable.
Long-distance signal transmission ᾠSince the laser light doesn’t disperse, it can be easily transmitted over long distances.
Low attenuation ᾠThe fiber is made of glass and laser is traveling through it, the signal transmitted has only 0.2 dB/km loss.
Transmission security ᾠOptical encryption and no presence of the electromagnetic signal make the data secure over optical fiber.
Applications of Optical Fiber
Optical fiber communication is mainly used in the telecommunication industry which uses the optical fiber for:
Telephone Signals transmission.
Internet Communication.
Cable Television Signal transmission.
Apart from it, optical fibre nowadays, is used everywhere in homes, industries, offices for long distance as well as for small distance communication.
Opotical Fiber Impact on IoT (Internet of Things)
and these things listed will explain to you how IOT would require Fiber Optics.
Fast Transmission Media - The future will be IOT and all of our devices and things will be connected to the internet, which needs good communication and high speed.
The only transmission media that supports such a requirement is Optical Fiber.
The future needs IOT and IOT need Optical fiber for best communication that could help reach Wireless data speed up to 100 Gbps speed, making communications and large size data transfer in seconds.
Data Security ᾠSecurity in IoT is the main concern when we think of large amount of data to be transferred between billions of devices connected together.
Hacking of data from communication media is possible unless it is Optical fiber.
The optical fibers are very difficult to hack and hacking them without being detected is like next to impossible.
So again, an optical fiber can help secure the data and transfer it at very high speed.
No data loss due to interference - The optical fiber cables can be installed anywhere (even underwater or at high-temperature areas) and don’t have any electromagnetic interference resulting in no data loss due to interference.
article/rf-energy-harvesting-converting-radio-frequency-into-electrical-energy
RF Energy Harvesting - Converting Radio Frequency into Electrical Energy
in detail.
How does RF Energy Harvesting work?
? The process is quite simple, it is just like the normal process of an antenna receiving a signal.
So, let us understand the process of conversion using a simple diagram.
, the energy is amplified or converted to the potential value as desired by the load.
There are many sources that transmit RF signals like satellite stations, radio stations, wireless internet.
Any application that has RF energy harvesting circuit attached with it, would receive the signal and convert it into electricity.
(Load) is maximum.
The impedance in an RF circuit is as important as resistance in the DC circuit for optimum power transfer between the source and the load.
(a special rectifier) circuit which rectifies the signal and also boosts the rectified signal based upon the application requirement.
to store the electricity and supplies it to the load (application) whenever needed.
What are the sources of RF signal?
As mentioned earlier, there are many devices using RF signals it means that there would be many sources for receiving the RF signal for harvesting the energy.
which can be used as a source of energy are:
Radio Stations: Old but worthy, the radio stations regularly emit RF signals which can be used as a source of energy.
TV Stations: This too is an old but worthy source which sends signals 24/7 and is considered as a good source of energy.
Mobile Phones & Base Stations: Billions of mobile phones and their base stations emit RF signals which as a result, are a good source of energy.
Wireless networks: There are a number of Wi-Fi routers and wireless devices present everywhere and they should also be considered as a good source for harvesting energy from the RF.
These are the major devices present all over the world which are the major sources of RF that can be used to harvest energy i.e.
generate electrical energy.
Practical Applications of Radio Energy Harvesting
system are listed below:
RFID Cards: The RFID (Radio Frequency Identification) technology uses the concept of Energy Harvesting which charges its ‘Tagᾠby receiving the RF signal from the RFID reader itself.
The application can be seen in Malls, Metros, Train Stations, Industries, Colleges, and many other places.
Research or Evaluation: The Company Powercast has launched an evaluation board- “P2110 Eval boardᾠthat can be used for research purposes or for evaluations of some new applications considering the required and received power and changes to be made after evaluation.
Apart from these practical applications, there are many fields where Energy Harvesting technology can be used like in Industrial Monitoring, Agriculture industry, etc.
Limitations of RF Energy Harvesting
With good applications and a number of advantages, there are some disadvantages too and these disadvantages are caused due to the existing limitation in that thing.
So the limitations for RF energy harvesting system are:
Dependency: The only dependency of the RF energy harvesting system is the received RF signals quality.
The RF value can be reduced due to atmospheric changes or physical obstacles and can resist the transmission of the RF signal, resulting in low power as output.
Efficiency: Since the circuit is made up of electronic components who lose their functionality with time and give poor results if not changed accordingly.
As a result, this would affect the system efficiency as a whole and provide improper output in return.
Complexity: The receiver for the system is needed to be designed based on its applications and the power storage circuit, which makes it more complex to build.
Frequency: Any circuit or device which is designed to receive an RF signal to harvest energy can be designed to operate only one frequency band and not multiple.
So, it is only limited to that band spectrum.
Charging Time: The maximum power output from the conversion is in milliwatts or microwatts.
So, the required power by the application would need a long time to produce.
Apart from these limitations, Energy Harvesting using Radio Frequency (RF) has many advantages as a result of which it has application in Automation Industry, Agriculture, IOT, Healthcare Industry, etc.
RF Energy Harvesting Hardware available in market
are:
Powercast P2110B: The company Powercast has launched P2110B which can be used for evaluation as well as for application-based use.
Applications:
Battery-free wireless sensors
Industrial Monitoring
Smart Grid
Defense
Building automation
Oil & Gas
Battery recharging
Coin cells
Thin-film cells
Low power electronics
Features:
High conversion efficiency
Converts low-level RF signals enabling long-range applications
Regulated voltage output up to 5.
Up to 50mA output current
Received signal strength indicator
Wide RF operating range
Operation down to -12 dBm input
Externally resettable for microprocessor control
Industrial temperature range
RoHS compliant
Powercast P1110B: Similar to the P2110B, Powercast P1110B has the following features and applications.
Features:
High conversion efficiency, >70%
Low power consumption
Configurable voltage output to support Li-ion and Alkaline battery recharging
Operation from 0V to support capacitor charging
Received signal strength indicator
Wide operating range
Operation down to -5 dBm input power
Industrial temperature range
RoHS Compliant
Applications:
Wireless sensors
Industrial Monitoring
Smart Grid
Structural Health Monitoring
Defense
Building automation
Agriculture
Oil & Gas
Location-aware services
Wireless trigger
Low power electronics.
Use of RF Energy Harvesting in IOT Applications
wireless sensors for their capability of providing sensor data directly on an IoT cloud, using a wireless gateway with no apparent source of energy.
By harvesting power from available RF energy sources, a new generation of ultra-low-power (ULP) wireless devices, such as IoT sensors, can be developed for low-maintenance applications like remote monitoring.
Energy harvesting is considered much like a “companionᾠtechnology to wireless communications since it can enable extended battery life for mobile devices and possibly battery-free operation for some electronic devices.
article/electromagnetic-interference-types-standards-and-shielding-techniques
Electromagnetic Interference (EMI) ᾠTypes, Standards and Shielding Techniques
which is a very common practice that designers have to keep in my mind to develop quality products.
We will look at EMI in detail and will examine its types, Nature, specifications and standards, coupling and shielding mechanisms, and best practices for passing EMI Tests.
EMI Standards ᾠHow it all started?
that may prevent them from performing the way they were originally designed to be.
These interferences might sometime even make the device completely malfunction that it might become dangerous to users.
It first became a concern in the 1950’s, and was primarily of interest to the military due to a few notable accidents arising from navigation failures due to Electromagnetic interference in navigation systems, and radar emissions leading to inadvertent weapons release.
As such the military wanted to ensure systems were compatible with one another and the operations of one does not affect the other as that could lead to fatalities in their craft.
Asides military applications, recently advancements in Medicine and Health related solutions like Pacemakers and other kind of CIEDs, have has also contributed to the need for EMI regulations as interference in devices like this could lead to life threatening situations.
and with the large number of EMC regulatory bodies that have been established.
What is Electromagnetic Interference (EMI)?
especially, are more likely to generate interference compared to others.
Since no device can operate in an isolated environment, it is important to ensure our devices adhere to certain standards to ensure interference is kept to the barest minimum.
These standards and regulations are known as the EMI Standard and every product/device to be used/sold in regions/country where these standards are law, must be certified before they can be used.
Types of Electromagnetic Interference (EMI)
Before we look at the standard and regulations, it is probably important to examine the type of EMI’s to better understand the kind of immunity that should be built into your products.
Electromagnetic interference can be categorized into types based on several factors including;
Source of EMI
Duration of EMI
Bandwidth of EMI
We will look at each of these categories one after the other.
on the other hand, refers to EMIs which occur as a result of the activities of other electronic devices in the vicinity of the device(Receiver) experiencing the interference.
Example of these type of EMIs include, Radio Frequency interference, EMI in sound equipment amongst others.
is EMIs that occur intermittently or within a very short duration.
Like the continuous EMIs, Impulse EMI could also be naturally occurring or man-made.
Example includes impulse noise experienced from switches, lightings and similar sources which could emit signals that cause a disturbance in the voltage or current equilibrium of connected nearby systems.
are EMIs which do not occur on single/discrete frequencies.
They occupy a large part of the magnetic spectrum, exists in different forms, and can arise from different man-made or natural sources.
Typical causes include arcing and corona and it represents the source of a good percentage of EMI problems in digital data equipment.
A good example of a naturally occurring EMI situation is “Sun Outageᾬ which occurs as a result of the energy from the sun disrupting the signal from a communication satellite.
Other examples include; EMI as a result of faulty brushes in motors/generators, arcing in ignition systems, defective power lines and bad fluorescent lamps.
Nature of EMI
, hence, it is critical to understand the nature of the EMI, to know which of them is dominant before the problem can be clearly addressed.
EMI Coupling Mechanisms
they Conduction, Radiation, Capacitive Coupling and Inductive Coupling.
Let’s take a look at the coupling mechanisms one after the other.
is the most popular and commonly experienced form of EMI Coupling.
Unlike for conduction, It does not involve any physical connection between the source and the receiver as the interference is emitted (radiated) via space to the receiver.
A good example of radiated EMI is the sun outage mentioned earlier.
exists when a changing voltage in the source capacitively transfers a charge to the victim
This refers to the kind of EMI which occur as a result of a conductor inducing interference in another conductor close by based on the principles of electromagnetic induction.
Electromagnetic Interference and Compatibility
that devices must meet to show that they are able to coexist with other devices and perform as designed without also affecting the performance of the other devices.
As such EMI standards are essentially part of the general EMC standards.
While the names are usually used interchangeably, a clear difference exists between them but this will be covered in a followup article.
According to Part 15 of Title 47:Telecommunications, of the FCC Standards, which regulates “unintentionalᾠradio frequency, there are two classes of devices; Class A and B.
Class A devices are devices which are meant for use in industry, offices, everywhere else but homes, while CLass B devices are devices meant for home use, notwithstanding its use in other environments.
Website.
the limits are;
For radiated emissions, it is expected that Class A devices stay within the limit below for the specified frequencies;
Frequency (MHz)
μV/m
30 to 88
100
88 to 216
150
216 to 960
200
960 and above
500
devices, the limits are;
Frequency (MHz)
μV/m
30 to 88
90
88 to 216
150
216 to 960
210
960 and above
300
More info on these standards can be found on the page of the different regulatory bodies.
Electromagnetic Shielding ᾠProtect your design from EMI
This is particularly common in most pre-certified communication modules and chips.
acts as an interference shield.
Ideally, the perfect EMC enclosure would be one made from a dense material like steel, fully sealed on all sides with no cables so no wave travels in or out, but several considerations, like the need for, low cost on enclosures, heat management, maintenance, power and data cables among others, render the such ideals impractical.
With each of the holes created, by these needs being a potential entry/exit points for EMIs, Designers are forced to take several measures to ensure the overall performance of the device is still within permissible ranges of the EMC standard at the end of the day.
Shielding Practical Considerations
Slots must be designed in such a way that their length and orientation relative to the RFI Frequency does not turn them to a waveguide, while their size and arrangement in the case of ventilation grilles should maintain a right balance between the airflow required to maintain thermal requirements of the circuitry and the ability to control EMI based on the signal attenuation required and the RFI Frequency involved.
They come in different types including, knitted wire mesh, and metallic spiral gaskets but several design factors (usually cost/benefits) are considered before the choice of gasket is made.
Overall, the number of slots should be as little as possible and the size should be as small as possible.
Certain enclosures may be required to have cable apertures; this must also be factored in the enclosure design.
In
are placed at specific locations at the edge of the cables.
On PCB Board level, filters are also implemented along input power lines.
Best Practices to Pass EMI Tests
, especially on the board level, to keep EMI in check include;
Use Pre-Certified Modules.
Especially for communication, using already certified modules reduces the amount of work the team needs to do in shielding and reduces the cost of certification for your product.
Pro Tip: Instead of designing a new power supply for your project, design the project to be compatible with existing off the shelf power supplies.
These saves you cost in certifying the power supply.
Keep current loops small.
The ability of a conductor to couple energy by induction and radiation is lowered with a smaller loop, which acts as an antenna
For pairs of copper printed circuit (PC) board traces, use wide (low impedance) traces aligned above and below each other.
Locate filters at the source of interference, basically as close to the power module as possible.
Filter component values should be chosen with the desired frequency range of attenuation in mind.
As an example, capacitors self-resonate at certain frequencies, beyond which they act inductive.
Keep bypass capacitor leads as short as possible.
Place components on the PCB with consideration given to proximity of noise sources to potentially susceptible circuits.
Position decoupling capacitors as close as possible to the converter, especially X and Y capacitors.
Use ground planes when possible to minimize radiated coupling, minimize the cross sectional area of sensitive nodes, and minimize the cross-sectional area of high current nodes that may radiate such as those from common mode capacitors
Surface-mount devices (SMD) are better than leaded devices in dealing with RF energy because of the reduced inductances and closer component placements available.
All in all, it is important to have individuals with these design experiences in your team during development process as it helps save cost in certification and also ensures the stability and reliability of your system and its performance.
article/drone-delivery-future-of-shipping-industry
Drone Delivery - Future of Shipping Industry
Drones have existed for a long time, but have gained popularity only in recent times.
These Unmanned Ariel Vehicles have gotten better, Cheaper and versatile with time.
Drones are helping to penetrate into various sectors, rather than being just limited to hobbyists.
?
Current Scenario of the Shipping Industry
The shipping industry has been hugely dominated by container ships.
As reported by CNBC, these ships transport more than 90% of the goods in the world.
The domination of container ships in the transport industry is clearly evident.
According to the Ministry of Shipping, around 95% of India's trading by volume and 70% by value is done through maritime transport.
The other modes of transport contributing to the shipping industry are trucks, planes, trains, and drones.
Ships are cheapest but slowest of all.
It can take over a month for goods to sail from Mumbai to New York.
Moreover, these ships are limited to ports therefore further transportation is handled by Trucks and trains.
Shipping via air is the fastest but its potential is limited due to heavy costs.
The demand for faster delivery has amped up delivery via air, making room for drones in this sector.
The global drone logistics and transportation market accounted for more than 24 million dollars in 2018, and that number is expected to grow to 1.6 billion dollars in 2027.
These growing numbers might be an indication of a major change in the shipping industry.
How does the Drone Delivery Work?
Before advancing further we must explore a little about the working of drone delivery system, do not worry we aren’t talking physics here.
Drones use rotors for liftoff, forward, backward movement and also for rotation.
So motors all around but what happens when a drone gets short on battery power and they will have to rush back to their power-stations to get their batteries recharged.
Two methods have been explored to tackle this situation so far.
The first coming straight from Amazon Air, which is planning to release drones from multiple dispatch centres around the country.
These drones from Amazon has can travel a distance of around 16kms.
For this to possible Amazon will require nationwide dispatch bases.
The other possible method for take-off has been discovered by UPS (American package delivery service).
In this case, vans from UPS will act as dispatch centres for drones.
Loaded from within the van, these drones will have the road-bound vehicle navigation system to deliver parcels.
process.
These autonomous drones use GPS to navigate to the desired location and are closely monitored for security reasons.
To prevent ground or air accidents these drones are equipped with automatic sense and avoid (SAA) systems.
While this is a basic overview, every other company is determined to develop a technology/ software of their for safer drone delivery.
Are companies making serious efforts for Drone Delivery?
We are pacing towards a future of drone delivery.
Companies like Amazon, Google, UPS, Zipline, DHL, Dominos and a few others are making serious efforts to get this tech into action.
Meaning drones hovering above our houses to deliver products will not be a thing from a futuristic movie anymore.
At current two designs are being majorly tested
a) Land and detach package and
b) from-air lower package to ground
Land and detach delivery requires the drone to land in a consumers garden, driveway.
Whereas, ‘from air lower package to groundᾠworks by delivering packages via a cable while the drone remains in air at a safe height.
There are many courier companies which have already started using drones to deliver packages.
Here is the list of few.
Amazon Air
Amazon is keen enough to implement this technology in real-world and their efforts have already started showing up.
With Amazon Air service in action, the e-commerce giant will be able to deliver packages up to 5 pounds in 30 minutes or less using small drones.
The company claims that these completely electric drones built by them are capable of flying up to 15 miles.
This year in June they showcased their new Drone design which is capable of vertical takeoffs and landings similar to a helicopter.
Amazon Air has its development centres in the United States, United Kingdom, Austria, France and Israel.
Google Wing
Wing a subsidiary of Alphabet Inc (Parent company of Google), has successfully established itself in Drone-based delivery sector.
As it became the first to receive Air operator’s certificate from the Federal Aviation Administration.
This certification permits a company to allow its operations as an airline in USA.
The company aims to reduce traffic congestion in cities and help reduce CO2 emissions.
It is also developing an unmanned traffic management platform that will allow unmanned aircraft to navigate around other drones, manned aircraft, and other obstacles like trees, buildings and power lines.
Wing owned drones can travel a distance of about 20kms while attaining a speed of up to 113 km/h.
These drones weigh around 4.8kg and are capable of carrying packages up to 1.5kg in weight.
DHL (china)
DHL is one of the largest logistic companies in the world has partnered with drone specialists EHang for using drones to deliver packages in Guangzhou, China.
This is the same company that broke a world record by lifting a single-seater autonomous flying taxi.
For this project, Ehang is using its Falcon series of drones which weigh around 9.5 kg and are capable of carrying a maximum load of 5.5kg.
These drones have a flight time of about 18 minutes when loaded and 38 minutes when empty at speeds up to 65km/hr.
UPS (U.S)
UPS is another company seeking certification from the FAA to take a lead in this race of drone delivery.
Back in 2016, the company conducted two test projects.
The first project was in partnership with Zipline aimed at providing medical facilities in Rwanda While the other was in collaboration with the drone manufacturer Cyphy works.
Earlier this year, the company partnered with another drone manufacturer, Matternet to deliver medical samples at a North Carolina hospital.
Which clearly indicates that the company is determined enough to get drone-based delivery in action.
Dominos (Newzeland)
Dominos is gearing to get your favourite pizza delivered even faster.
The pizza franchise has already begun delivering pizza’s via drones in New Zealand in partnership with Flirtey.
Currently, the feature is only available to select customers.
However, both the companies are working to scale drone delivery to other regions of the world.
These futuristic vehicles come with certain advantages and disadvantages.
So, let us quickly take a sneak peek.
Advantages of Drone Delivery
The requirement of faster delivery services has gotten drone delivery into action.
Current services like Prime Air, Goggle Wing, Zipline have already showcased their capabilities with insanely fast deliveries.
ᾠDrone delivery will certainly benefit with heavy road congestions, cutting down the distance travelled by delivery vehicles.
Reduced vehicles on the road will help prevent accidents, saving lives.
ᾠDrone delivery would help to reduce emission of greenhouse gases as they are completely electric in nature, except a few hybrid drones (fuel & electric)
Disadvantages of Drone Delivery
The drones currently used for delivery purposes are not capable of carrying heavy loads.
Drones run on batteries and their flight time is hugely dependent on these batteries.
It is worth noting, that the flight time reduces with increasing loads.
Drones these days are equipped with excellent sensors, but might be an issue considering future prospects as drone delivery will increase in coming days.
These drones as usually autonomous and are dependent on GPS for navigation.
These might face issues in densely populated areas.
Delivery drones have cameras and they constantly record footage and not everyone around will be comfortable with it.
Are Drones really the future of shipping industry?
To be honest, this is a difficult question to answer and the internet is full of opinions citing this question.
Delivery drones are certainly the buzzwords these days, and e-commerce and technology giants are looking forward to embracing it.
But there is still time when we see drones around flying around seamlessly delivering parcels.
Factors such as flight legislation, flight time, sense and avoid technology and parcel weight are major obstacles that delivery drones need to overcome.
Looking from an economic perspective, drones need to make as many deliveries as possible in the shortest possible time, in order to make a profitable run.
It is evident that current delivery drones are not capable of delivering many deliveries.
Compare this with a delivery truck and you will find that these are certainly better than drones, delivering hundreds of parcels in a single run.
Drone delivery has a lot to overcome before it gets into real action.
But none can deny that it is here to stay and is the certainly the future of shipping industry.
article/top-media-server-software-for-music-streaming-on-raspberry-pi
Top 10 Media Server Software for Music Streaming on Raspberry Pi
for playing music, videos, and live streaming of all sort of multimedia.
Media Servers typically aggregate media files from all of the users favorite sources including local drives, internet based music platforms like spotify, and video streaming platforms like YouTube, providing the user with a single point access to all of their favourite songs, movies and shows.
with I2S, double HDMI port, higher ram, processing speed, and better connectivity options, the ability of the Pi to serve as the perfect media server just got tuned up.
comparing them, one with the other, examining their pros and cons to help users identify which is best for your desired goal.
In addition to this, we will pick one of the software and share how to set it up on your Raspberry Pi in next article.
Music Player Types
, including;
Kodi/XBMC
Plex
OpenELEC
OSMC
RuneAudio
Volumio
Xbian
LibreELEC
Emby
Mopidy
We will go over these softwares one after the other.
1. Kodi
is by far the most popular of the pack.
Formerly known as XBMC, Kodi is a free and open source media player software which can playback media files including audio, video and display pictures locally stored on a drive connected to the computer on which the software is running or stream videos, sounds and pictures from the internet.
It is capable of playing this media files created in any of the popular file formats.
Kodi comes as a software to be installed on the Raspberry Pi as such, even though it is designed to run in full screen mode, it can be minimized to perform other tasks on the Raspberry Pi, making it a good fit for scenarios where you want to be able to use the Raspberry Pi once in a while for projects other than the media server.
We covered KODI setup on the Raspberry Pi in one of our previous tutorial here.
Kodi runs on almost any platform making it a very versatile and useful tool.
2. Plex
is a client-server media player system.
The server houses all the media file and can be connected to the internet to access media files stored across several internet channels.
The Plex Client on the other hand makes it super easy to access or stream all the media files from the server, making Plex a perfect way to share music.
Plex is perfect for applications that require playing different kinds of music at different locations or say on different devices.
For instance, two users in different rooms in a house can play different songs from the same plex server.
How Plex works can be understood from the below points:
The Plex Media Server can run on many Operating Systems like Windows, macOS and Linux etc.
Plex organize all you media files, whether it be music, movies, photos, shows, in clean manner with posters and thumbnails and also show ratings and other things from the online services.
Here we are using Raspberry Pi as Plex Server.
Media players are the clients running on the client devices like mobile, computer etc.
Clients can access the media files from the Plex Server.
It effectively allows you keep all your media files in one place and access them from any device.
was also covered in a previous tutorial here.
Plex has both free and paid version and needless to say, the paid version has more bells and whistles compared to the free version.
3. OpenELEC
is a jeOS (just enough operating system) based media server.
The operating system possess all that is needed to get the Raspberry Pi going as a media server only.
emulators and DVR plugins.
It is similar to the XBMCbuntu (formerly XBMC Live) distribution but specifically targeted to a minimum set-top box hardware like the Raspberry Pi.
due to its lightweight and the fact that it was created to serve that purpose only.
amongst others, each with a distinguishing feature, appealing to a variety of users.
4.OSMC
specifically configured to serve as a media server with the only difference being the flexibility in configurations which OSMC brings to the table.
also built around KODI but with a more lightweight and optimized skin than OpenELEC which makes it feel a bit faster when navigating around Kodi.
OSMC possesses the same limitations with running a lightweight OS dedicated to one task but it provides a significantly better overall user experience, when compared with OpenELEC (and its spinoffs).
It is easier to configure and is more customizable.
5. RuneAudio
Its at this point that users should consider the use of solutions like Rune Audio.
based on a custom built linux distro, with only the features and functions necessary for high quality music playback retained and other unused aspects stripped away.
The OS is optimized to get the best results from the Raspberry Pi, tweaking its parameters to ensure what is obtained at the end of the day is a high quality, Hi-Fi System.
Rune can be controlled by any device on the same local network as the Raspberry Pi.
It sets up a web user interface through which users can log-on and take actions like select the next song to play etc.
Like most of the other music players, it is also free to use and open source.
6. Volumio
is a media server for the Raspberry Pi dedicated to audiophiles as it supports only music.
It was designed specifically for the Raspberry Pi and as is based on the Raspbian distribution, giving it the ability to manage the music library on the Pi.
Its an easy to use software, supports all types of files (mp3, FLAC, Alac, Aac, Vorbis, etc.), and works with DAC expansion cards for the Pi giving it HI-FI capabilities with increased sound quality and comfort.
as such, like the others, it turns the Raspberry Pi to a single purpose device.
Like most of the other media players, Volumio can be controlled by anyone on the same local network as your Pi, giving everyone in the room or within the Coverage area of the WiFi, with the required access the ability to select the next song and serve as the DJ.
7. Xbian
ᾠof the Raspbian image.
Xbian was created with lightweight devices like the Raspberry Pi in mind with a simple goal of delivering the fastest KODI solution for the Pi.
as such, it also turns the pi into a single function device.
Unlike the other software however, Xbian over time has produced a super sleek render of KODI on the Pi with very smooth UI, User friendly configuration and support for Airplay.
To cap its features, Xbian also has an auto update features which means it automatically updates itself whenever a new stable release is available, giving the user unlimited access to new features as soon as they are released.
8. LibreELEC
ᾠbased on a Linux distro, for KODI.
It launched in 2016 when its split from OpenELEC was announced with the team citing creative differences as a reason for the split.
It is a conservative version of the OpenELEC with the team more focused on ensuring it works as it should with emphasis laid on pre-release testing and post-release change management.
As a result of this, it has grown to become the most stable OpenELEC fork, arguably more stable than OpenELEC itself.
Asides its stability and freedom from crashing, experienced with the other forks, it features a uniquely slicker feel when running Kodi.
The strong support possessed by LibreELEC which facilitates monthly updates and patches to get it to work with new updates of KODI are some of the few strong points which LIbreELEC has over others, especially over OpenELEC.
9. Emby
running on several devices including mobile phones and smart TVs.
rather than an operating system.
Emby is however open source unlike Plex but it offers almost the exact same features with the only difference being the fact that Plex has achieved a lot of stability over time, working on several more clients than Emby which is the new kid on the block with a growing reach.
By direct comparison, there is not much to choose from between Plex and Emby asides the fact that the interface for Plex is a bit easier to use while that of Emby offers flexibility which users may come to appreciate later but may find it difficult to take advantage of, in the early days.
10.
Mopidy
Last but not the least to be examined today is Mopidy which is again, for the audiophiles.
capable of playing only music stored on local disk or attached drives but via its several extensions, additional sources to stream from, and frontends for controlling Mopidy can be added.
to mention a few, and the playlist etc can be controlled through client interfaces running on phones tablets or PCs using MPD web clients.
It is one of the most maker friendly media server due to its extension support and the fact that it was built with python which is one of the most popular maker languages for the Raspberry Pi.
This makes it easy for users to connect things like pushbuttons to Mopidy to, for instance, control the music volume or move to the next track.
Several wonderful projects have been built in the past with this, Including the Pi Music Box, and the kickstarter funded modern cloud jukebox called Gramofon.
in our next tutorial.
As much as these media server softwares possess unique differences, time has made everyone of them incorporate a little bit of features from one another which makes spotting the difference quite the work.
As such, I believe every user should really try out as much of these softwares are possible and quietly examine the feel, navigation etc because at the end of the day, the one to be chosen should be the one which resonates with you.
article/what-is-sigfox-basics-architecture-and-security-features
An Introduction to Sigfox Technology ᾠBasics, Architecture and Security Features
in our previous article and hence in this article we will learn about a similar wireless communication protocol called Sigfox and its significance in connected technology.
What is Sigfox Technology
modulation to connect to the base stations.
Low power consumption ensures that remote devices runs for long with minimal battery charging or maintenance.
Sigfox enables IoT communication over long distances making it possible to transmit with minimal base stations.
The Sigfox network uses cellular style approach to enable the remote nodes to use internet to communicate with base stations.
This facilitates remote control and data collection from the Sigfox nodes over a wide geographical area as long as there is internet connectivity.
Features of Sigfox
like smart electricity meters, smart watches etc.
Let’s take a look at the features of Sigfox which makes it as a preferable network.
that accommodates resistant and resilience to interference.
The Sigfox infrastructure uses random access that facilitates frequency and time diversity.
The use of uplink and downlink bandwidth allows consistency regardless of the radio link used.
and gives Sigfox advantage over other technologies.
Sigfox consumes only a few nano amperes when idle, this rate of power consumption is negligible further enhancing efficiency.
due to minimal interference.
However, in town centres where there is a lot obstruction the Sigfox range reduces to 10km.
since spread spectrum signals are interfered by UNB signals.
In Europe, the Uplink has a bandwidth of 100Hz while in the USA the bandwidth exceeds to 600Hz.
The European Union has limited the maximum power to be 25mW.
The downlink has a channel bandwidth of 1.5KHz and a data range of 600 bps.
The downlink further limits the maximum power output to 500mW.
The optimal resilience to interfere facilitate Sigfox to function effectively in the ISM band.
This allows it to transmit even under jamming signals.
However, the low noise overlap induces intrinsic ruggedness to the Ultra-Narrow band.
As a result, for a message to be transmitted, the signal should have at least 8 dB.
Sigfox Network Architecture
for billing and ordering, and Radio Planning for supporting network deployment and monitoring.
The public internet connects the two layers over secure VPN connections.
The data from the IoT devices is sent through air to the base stations, then goes through the backhaul which uses DSL connectivity with 4G backup.
Satellite connectivity is used as backup in places where DSL and 4G are not available.
Message processing is also handled by the backhaul, these messages arrive on the core network as many replicates but only one copy is stored which can be accessed by customers through a web interface.
Sigfox security and privacy
to get a better idea on how to secure your IoT devices.
Now let’s take a look at the different security features in Sigfox.
that restricts IoT objects to connect or communicate using the internet protocol.
To communicate over the internet, an object sends a radio message that is picked up by the available access stations.
The access station then relays the message to the Sigfox support system that in turn transmits it to the specified destination.
The Sigfox support system also transmits the response to the sender object through the base stations.
The security firewall thus secures the IoT objects from internet related attacks.
; it also provides an extra anti-eavesdropping mechanism.
The Sigfox’s IoT chain involves authentication keys stored which are stored by devices and the customer, this key will be required to access the data stored by the Sigfox System.
As a result, Sigfox’s data mechanisms guarantees security within the diverse ecosystem and different local regulations.
The authentication key for every device is unique meaning that a compromise of a device’s authentication security key does not affect the security of other devices.
However, the security of any device is left at the discretion of the manufacturer.
Application of Sigfox
Sigfox technology is suited for low cost M2M application that operate over a wide area coverage.
These areas include;
People, Goods or other type of Asset tracking.
Smart metering communication in the energy sector.
Communication of mHealth applications
Management of automotive communication in the transport sector
Remote control and monitoring.
Security.
Sigfox module manufacturers
RFIC.
These microcontrollers operate at a frequency range of 860-930 MHz.
This frequency range supports an output power of +14 dBm that can be enhanced to +20 dBm in case of poor signal areas.
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WiSOL Co.
LTD
TD1207
TD Next
SN10-11
InnoComm
ABZ Sigfox RC1
Murata Manufacturing Co.
LTD
SiPy 14dB
Pycom
S-Wing: Sigfox Extension board for Bosch XDK for Zone 2&4
InnoComm
S-Wing: Sigfox Extension board for Bosch XDK for Zone 3
Understanding Real Time Operating System (RTOS) and How to use it for your next Embedded Design
Embedded systems have a wide range of application in all the electronic devices around us, an evident example is the mini laptop that we carry around with us all the time, yes I am referring to our mobile phones.
What is RTOS?
which decides which instruction to execute first and thus executes the instructions of multiple programs one after the other.
Technically an RTOS only creates an illusion of multi-taking by executing paralleled instructions one at a time.
This makes RTOS suitable for various applications in real world.
In RTOS for any input whenever a logic has been evaluated which gives the corresponding output.
This logic is measured on the basis of not only the logical creativeness but also on the time duration in which the specific task has been performed.
If a system fails in performing task in that specific duration of time it is known as system failure.
Why RTOS??
Availability of drivers: There are many drivers available within RTOS, which allows us to use them directly for various applications.
Scheduled files: RTOS takes care of scheduling so instead of focusing on scheduling any system we can simply focus on developing application.
For example, task scheduling files are used to define certain actions whenever a set of conditions are met.
RTOS uses certain advanced algorithms for scheduling typically running, ready and blocked states which while running RTOS keeps more focus on developing application rather than scheduling.
Flexibility of adding features: Within RTOS even if you are willing to add new features , you can simply add it without disturbing the existing features
Difference between Real time Operating System & Operating System
There are various differences between real time operating system and operating systems like Windows, Linux etc.
Let’s have a look at them one by one with the help of table format:
S.No
Operating System
Real time System
1
Time sharing is the basis of execution of processes in operating system
Processes are executed on the basis of the order of their priority
2
Operating system acts as an interface between the hardware and software of a system
Real time system is designed to have its execution for the real world problems
3
Managing memory is not a critical issue when it comes to execution of operating system
Memory management is difficult as based on the real time issue memory is allocated , which itself is critical
4
Applications: Office , Data centers , System for home etc
Applications: Controlling aircraft or nuclear reactor , scientific research equipments
5
Examples : Microsoft Windows , Linux ,OS
Examples: Vx Works ,QNX , Windows CE
Types of RTOS
We can categorize real time operating system majorly into three parts namely
Hard real time operating system
Soft real time operating system
Firm real time operating system
Let’s start understanding this type of operating system using an example, the live example of it is flight control system.
Within flight control system whatever tasks is given by the pilot in the form of an input it should be performed on time.
In a hard real time Operating system, system failures can be tolerated.
The features of hard RTOS are:
To perform tasks on time
Failure to meet deadline is fatal
Guaranteed worse case response time
Can lead to system failure
Easiest example of using soft RTOS is online database, as within soft RTOS the parameter we are more worried about is speed.
Hence, the features of soft RTOS are:
Tasks should be performed as fast as possible
Late completion of tasks is undesirable but not fatal
There is a possibility of performance degradation
Cannot lead to system failure
Robot arm which is used to pick objects can be considered as among one of the example of firm RTOS.
Here, within this firm RTOS even if the process is delayed it’s tolerated.
Benefits of using free RTOS
The following are the advantages of using RTOS in your applications.
No firewall issues
Low bandwidth for enhanced performance
Improved security and privacy
Low cost, due to reduction in hardware and software components used for development
Some major issues related to RTOS
Now, despite of having many advantages for RTOS in real world application, it has various disadvantages also.
Some of the issues related to it are discussed here.
Interrupts are normally used in programs to halt the executing program to divert the flow to some other important part of the code.
Here, within RTOS since quick response time is required; it is recommended that interrupts should be disabled for a minimum possible time.
Since, the kernel should also respond for various events it is required to have lesser size of kernel so that it should fit properly within ROM
Sophisticated features of RTOS should be removed as there is no concept of as such virtual memory within it.
How to use RTOS
you normally have to use the Tornado or the FreeRTOS development environment.
Let us take a brief look into both these development environment.
applications on the target system.
Tornado consists of three basic elements which are listed below.
1) VxWorks
2) Application building tools (compiler and associated programs)
3) Integrated development environment, which can manage, debug and monitor VxWorks application
for configuration and build.
Very important point which comes into picture here is that while installing tornado within your system the installation directory should use the pathnames as:
installDir/target.
For example if you wish to store your tornado in C:\tornado on a windows host the full pathname should be identified in that case as installDir/target/h/vxworks.h.
WindRiver GNU helps us in providing a graphical analysis regarding the interrupt involved during execution as well as the memory usage report.
For example, the above stated view of WindRiver explains the associated processor number along with the priority of tasks (tLowPri & tHighPri).
Idle state i.e green color line stated the time period for which processor is not in its working state, which is observed to be after every few seconds.
t1 , t7, t8 & t9 are nothing but the various processors used.
Here, we are selecting only t7 processor.
Hence, this Windriver is capable of invoking both VxWorks and application module subroutines.
You can launch the Windriver application either form the tornado launch tool bar (-> i button) later click on menu and then click on shell.
Lastly, from the command prompt type ᾦgt;windsh target serverᾮ
Here, munching refers to additional host processing step.
Compile C++ application source program and get for example hello.cpp file .
Later run it to munch on the .o and compile the generated ctdt.c file.
Further, link the application with ctdt.o to generate downloadable module , hello.out within VxWorks.
The output after executing this VxWorks will be a make file which will be using on some target .
Generally, whenever we begin with RTOS we generally prefer Vx Works RTOS.
But , here let’s have a discussion in brief regarding the Free RTOS , which can also be used to by beginners to go through concept of real time operating system .
Free RTOS is developed by Richard Barry and FreeRTOS team ,also it is owned by Real time engineers ltd but it is free to use and can be simply downloaded by clicking on the link below
Latest version of free RTOS being used at the time of this article is version 10, stated as FreeRTOS V10.
the code which you wrote along with the process of execution will be similar for both.
There are many other benefits of using free RTOS over Vx works and other RTOS operating tools.
Some of them can be stated as:
Provides easier testing
Promotes the concept of code reusability
Lesser idle time
Easy maintainability
Abstract out timing information
, where Kernel refers to the central component of an operating system which is present within the free RTOS makes it accessible to use for various applications.
Since it is easy to attach expanded modules on operating systems to get its more applications free RTOS becomes more powerful.
is a free web device used to transfer the information from the device to the browser.
is in trend and every IOT device we will be accessing has a unique URL over the internet and the technology allows secure and extremely low bandwidth point to point connections.
In the absence of internet connectivity this combination can be helpful.
Therefore, free RTOS is a popular choice when it comes to implementing IOT.
tutorial/diode-clamper-circuits
Diode Clamper Circuits
The difference between a clipper and a clamper is that the clipper circuit changes the shape of the waveform but clamper just manipulates the DC level of output signal.
) can be calculated using the below formula:
t (Tau) = RC
Where R is the resistance used in the circuit and C is the capacitance of the capacitor.
based upon the clamping:
Positive Clamper
Negative Clamper
Biased Clamper
Positive Clamper
When the negative cycle clamps/shifts above the zero voltage level, then the clamper circuit is called as Positive Clamper because the whole signal is shifted to the positive side.
It’s a really simple circuit to design, you just need to follow the circuit diagram below:
First connect the transformer’s 12V (AC source) pin to the capacitor and then connect diode’s negative terminal to the other terminal of capacitor and positive terminal to 0V pin of the transformer.
Now connect a 10K resistor in parallel to the diode.
Connect the channel A of oscilloscope to the input side and channel B to the output side as shown in figure.
Now you are ready to go.
Turn ON the transformer and oscilloscope and adjust both of the channels to 0V line and you’ll see that the channel B is shifted upwards as shown below:
And the output voltage becomes:
Vo= Vi + Vm
level.
This shifting solely depends upon the charge stored by the capacitor.
Negative Clamper
When the positive cycle clamps/shifts below the zero voltage level, then the clamper circuit is called as Negative Clamper because the whole signal is shifted to the negative side.
The circuit diagram to build an Negative clamper is shown below:
First connect the transformer’s 12V (AC source) pin to the capacitor and then connect diode’s positive terminal to the other terminal of capacitor and negative terminal to 0V pin of the transformer.
Now connect a 10K resistor in parallel to the diode.
Connect the channel A of oscilloscope to the input side and channel B to the output side as shown in figure.
Now you are ready to go.
Turn ON the transformer and oscilloscope and adjust both of the channels to 0V line and you’ll see that the channel B is shifted downwards as shown in the figure below.
The channel A is yellow colored and channel B is blue colored.
the diode gets reverse biased and acts as a open circuit.
So, the output voltage becomes:
Vo= Vi + Vm
level because it is the negative voltage.
This shifting solely depends upon the charge stored by the capacitor.
Biased Clamper
A biased clamper is nothing different than positive and negative clampers discussed earlier.
It just consists of a bias voltage with diode.
then it just gets added with output voltage and it will shift to more positive level as the bias voltage.
then it just gets added with output voltage and it shifts to more negative level as the bias voltage.
then instead of shifting to the positive level it will shift to some negative level because it will get subtracted from output voltage.
then instead of shifting to the negative level it will shift to some positive level because it will get subtracted from output voltage.
voltage below.
The negative clamper can also be designed in the same way just by reversing the diode and bias voltage.
Bias voltage can be of any value but remember it should not be greater than or equal to the input voltage because in that case either you will not get any output, or the clamping may get reversed.
tutorial/introduction-to-relay-logic-control-symbols-working-and-examples
Introduction to Relay Logic Control - Symbols, Working and Examples
, its symbols, working and how they can be used as Digital Logic Gates.
Working of a Relay
Relay act as switch which is operated by a small amount of current.
The relay has two contacts-
Normally open (NO)
Normally Close (NC)
In the figure given below, you can see there are two sides of a Relay.
One is primary coil which acts as a electromagnet on passing current through it and other one is secondary side having NO and NC contacts.
, the switch is closed and the circuit is completed and hence current flows through the circuit.
This change of state in the contacts occur whenever a small electrical signal is applied i.e.
whenever a small amount of current flows through the relay, the contact changes.
This is explained through the figures below-
.
Relay Logic Circuits - Schematic/Symbols
The extreme left rail is at the supply voltage potential and is used as an input rail.
The extreme right rail is at zero potential and is used as the output rail.
Particular symbols are used in relay logic circuits to represent different circuit components.
Some of the most common and widely used symbols are given below-
The given symbol indicates a Normally Open contact.
If the contact is Normally open, it would not allow any current to pass through it and hence there will be an Open circuit at this contact.
This symbol is used to indicate Normally Close contact.
This allows the current to pass through it and acts as a short circuit.
This push button allows current to flow through it to the rest of the circuit as long as it is pressed.
If we release the push button, it becomes OFF and no longer allows the current to flow.
This means in order to carry the current the push button has to remain in the pressed state.
The OFF push button indicates an open circuit i.e.
it does not allow the flow of current through it.
If the push button is not pressed, it stays in OFF state.
It can transit into ON state to carry the current through it once it is pressed.
The relay coil symbol is used to indicate control relay or motor starter and sometimes even contactor or timer.
The given symbol denotes Pilot Lamp or simply a bulb.
They indicate the machine operation.
Relay Logic Circuit ᾠExamples and Working
The working of a relay logic circuit can be explained through the given figures-
This figure shows a basic relay logic circuit.
In this circuit,
Rung 1 contains one Push button (initially OFF) and one control relay.
Rung 2 contains one Push button (initially ON) and one Pilot lamp.
Rung 3 contains one NO contact and one Pilot lamp.
Rung 4 contains one NC contact and one pilot lamp.
Rung 5 contains one NO contact, one pilot lamp and a sub-rung with one NC contact.
To understand the working of the given relay logic circuit, consider below figure
, the push button is Off and hence it does not allow the current to pass through it.
Therefore, there is no output through rung 1.
the push button is On and therefore, current passes from the high voltage rail to the low voltage rail and the Pilot Lamp 1 glows.
, the contact is Normally Open, therefore Pilot lamp 2 remains Off and there is no flow of current or output through the rung.
, the contact is normally Close, thereby allowing the current to pass through it and giving an output to the low voltage rung.
no current flows through the main rung as the contact is normally Open but due to the presence of the sub-rung, which contains a normally close contact, there is a flow of current and hence the pilot lamp 4 glows.
Basic Logic Gates Using Relay Logic
can also be realised using relay logic and have a simple construction using the contacts as given below-
is as shown ᾍ
A
B
O/P
0
0
0
0
1
1
1
0
1
1
1
1
This table is realised using the relay logic circuit in the following manner ᾍ
In this, the Pilot lamp will turn On whenever any one of the inputs becomes one which makes the contact associated with that input as normally close.
Otherwise, the contact remains Normally open.
is given as ᾍ
A
B
O/P
0
0
0
0
1
0
1
0
0
1
1
1
Relay logic realisation of AND gate is given by ᾍ
The contacts are connected in series for AND gate.
This means that the pilot lamp will turn ON if and only if both the contacts are Normally close i.e.
when both the inputs are 1.
is given by ᾍ
A
O/P
0
1
1
0
The equivalent relay logic circuit for the given NOT gate truth table is as follows ᾍ
The pilot lamp lights up when the input is 0 so that the contact remains normally close.
As the input changes to 1, the contact changes to normally Open and hence the pilot lamp doesn’t light up giving the output as 0.
truth table is as follows ᾍ
A
B
O/P
0
0
1
0
1
1
1
0
1
1
1
0
The relay logic circuit as realised for the given truth table is as ᾍ
As two Normally close contacts are connected in parallel, the pilot lamp lights up when one or both the inputs are 0.
However, if both the inputs become 1, both the contacts become Normally Open and hence the output becomes 0 i.e.
the pilot lamp doesn’t light up.
is given by the following table ᾍ
A
B
O/P
0
0
1
0
1
0
1
0
0
1
1
0
The given truth table can be implemented using the relay logic as follows ᾍ
Here, two normally close contacts are connected in series which means the pilot lamp will light up only if both the inputs are 0.
If any one of the input becomes 1, that contact changes to normally open and hence the flow of current is interrupted, thereby causing the pilot lamp not to light up, indicating 0 output.
Disadvantages of RLC over PLC
Complex wiring
More time to implement
Comparatively less accuracy
Difficult to maintain
Fault detection is hard
Provide less flexibility
tutorial/schottky-diode-characteristics-parameters-and-applications
Schottky Diode ᾠCharacteristics, Parameters and Applications
and how it can be used in our circuit designs.
Schottky Diode Symbol
can easily be used to distinguish Schottky diode from other diodes when reading a circuit diagram.
Throughout the article we will be comparing the Schottky diode with regular diode for better understanding.
image is shown below.
What makes Schottky Diode Special?
To understand this better, let connect a Schottky diode and a generic diode to an identical and circuit and check how it performs.
than a typical PN-junction diode.
Disadvantages of Schottky diode
If Schottky diode has very low voltage drop and high switching speed offering better performance then why do we even need generic P-N junction diodes? Why don’t we simply use Schottky diode for all circuit designs?
than regular rectifier diodes.
Schottky Diode vs Rectifier Diode
A brief comparison between PN- diode and Schottky diode is given in the below table:
PN- Junction Diode
Schottky Diode
PN-junction diode is a bipolar device means current conduction happen due to both minority and majority charge carriers.
Unlike PN- junction diode, Schottky diode is a unipolar device means current conduction happens due to majority charge carriers only.
PN- Junction diode has a Semiconductor- Semiconductor junction.
While Schottky diode has metal- Semiconductor junction.
PN- Junction diode have large voltage drop.
The Schottky diode has a small voltage drop.
High On state losses.
Low On state losses.
Slow switching Speed.
Fast switching speed.
High Turn On voltage (0.7 volts)
Low turn On voltage (0.2 volts)
High Reverse Blocking Voltage
Low Reverse Blocking Voltage
Low Reverse Current
High Reverse Current
Structure of Schottky Diode
Due to this property, Schottky diodes are known as unipolar devices, unlike typical PN-junction diodes that are bipolar devices.
Width of the Schottky barrier depends upon the type of metal and semiconductor materials that are used in junction formation.
, and current will start flowing in reverse direction, and this can damage the components connected to the Schottky diode.
Schottky Diode V-I Characteristics
One important characteristic that is to be considered when selecting your Diode is the Forward Voltage (V) versus Forward Current (I) graph.
The VI graph of the most popular Schottky diodes 1N5817, 1N5818 and 1N5819 is shown below
V-I characteristics of Schottky diode are very similar to typical PN-junction diode.
Having a low voltage drop than a typical PN-junction diode allows Schottky diode to consume less voltage than a typical diode.
From the above graph, you can see that 1N517 has the least forward voltage drop compared with the other two, it can also be noted that the voltage drop increases as the current through the diode increase.
Even for 1N517 at a maximum current of 30A the voltage drop across it can reach as high as 2V.
Hence these diodes are normally used in low current applications.
Parameters to consider while selecting your Schottky diode
, the frequency rating of the diode should be high.
Some common and important parameters for a diode that you should keep in mind are listed below:
The voltage dropped to turn on a forward-biased diode is forward voltage drop.
It varies according to different diodes.
For Schottky diode typically the turn-on voltage is assumed to be around 0.2 V.
The particular amount of reverse bias voltage after which the diode breaks down and start conducting in the reverse direction is called Reverse Breakdown Voltage.
Reverse breakdown voltage for a Schottky diode is around 50 volts.
It is the time taken to switch the diode from its forward conducting or 'ON' state to the reverse 'OFF' state.
The most important difference between the typical PN-junction diode and the Schottky diode is the reverse recovery time.
In a typical PN-junction diode reverse recovery time can vary from several microseconds to 100 nanoseconds.
Schottky diodes do not have a recovery time, because Schottky diode doesn’t have a depletion region at the junction.
Current conducted from a semiconductor device in reverse bias is reverse leakage current.
In the Schottky diode, increasing the temperature will significantly increase the reverse leakage current.
Applications of Schottky Diode
Schottky diodes have many applications in the electronics industry because of their unique properties.
Some of the applications are as follows:
and clamper circuits are commonly used in wave shaping applications.
Having a low voltage drop property makes the Schottky diode useful as a clamping diode.
and DC motor to prevent supercapacitor from discharge through DC motor.
Forward biased Schottky diode doesn’t have any minority charge carriers, and due to this, they can switch more quickly than the typical PN-junction diodes.
So Schottky diodes are used in because they have lower transition time from the sample to the hold step and this results in a more accurate sample at the output.
by following the link.
article/what-is-blockchain-and-how-it-is-used-to-keep-the-data-secure
What is Blockchain and how can it be used to keep your data secure
Today Human civilization is highly dependent on computers and other machines.
Everything around us from a simple alarm clock, to a complicated online banking system, works based on the program written for it.
But how dependable are these programs, it is okay to wake up late when your alarm clock fails you, but think about losing your life’s savings just because your banking system was compromised.
In fact, an article from Forbes states that in 2017 banks have lost about $16.8 billion to cybercriminals.
This puts a big frown on our face, if these programs are subjected to loopholes, How can we trust them to drive our future autonomous cars? How can we trust them to automatically administer drugs and help take critical decisions in biomedical field?
Behold! The power of Blockchain
such as Visa, MasterCard etc, takes a small amount of fees on every transaction and we allow this for the trust factor which is being created by the human touch behind it.
And through the codification of trust with the help of bitcoin these transactions are all safe without relying on any trusted third party.
, smart contracts, smart appliances, supply chain and etc.
In this article we will learn more about Bitcoin and it potential to make significant changes to technology as we know today.
What is Blockchain and how does it work?
and the only available identity is the cryptographic public address.
So that means person is present in public and all of its transaction are available but all under a cryptographic code name.
So instead of seeing kanika sent 1 BTC (Bitcoin), you would see something like
1MF1bhsFLkBzzz9vpFYEmvwT2TbyCt7NZJ sent 1 BTC
Here’s a transaction data of 1MF1bhsFLkBzzz9vpFYEmvwT2TbyCt7NZJ person
of the Blockchain is that one cannot just write off the books to save him/them from the embezzlement or laundering the money.
In real world where people just change or edit the details of the documents to save themselves is not possible in Blockchain.
Here it is intelligently prevented and that’s also the reason for why Blockchain is named as Blockchain.
is that encryption can be reversed i.e.
decrypted but hashing can’t be reversed or is very hard to revere as compared to decryption.
into the data field of calculator and see what is the output in the form of SHA 256 hash.
So the conversion into SHA 256 gives a 256-bit (32-byte) code which is unique.
If we input the text “circuit digestᾠwe get the output as
394c19455b15b23783bd52228a698695d9454c806d983ae7bfe3bd80d32e1ac7
Now if we change the input a little say we make the first letter capital, whole of the code will change, even one can’t even detect the minute change through the code.
has changed into
e06ed37daa54ca41c6a2ee656c50a703d85fae76f0954534ec137983f6f37062
SHA ᾠ256 can convert any string no matter how long it is, into 256-bit character length.
This factor becomes really important when one is dealing with large amount of data and transaction, so instead of remembering the full length data one has to only remember the fixed length hash.
, which only differ in a single case letter.
, which contains the data and hash pointer which significantly points to the previous block, now the hash pointer is not different from a simple pointer, but instead of containing the address of the previous block it contains the hash code of the data of the previous block.
block and then eventually the second block and will continue further and to change the whole chain so practically it isimpossible because of the decentralized structure of it.
These three principles give Blockchain the immutability and strength that it can be used in vast application space from security to management.
How Blockchain can drive the IoT Ecosystem more securely
, all the data is handled by the peers or nodes of the network.
On the other side the centralized structure of IoT creates a problem, where a million of devices of the scale of citywide network are expected to be leveraged for entering into a system.
A single malicious device in the IoT network can take down the whole structure and not only IoT network but also other network which are in relation with the central server of the devices.
and can exhibit a better synergy.
which involves 126 unique patents focusing purely on the IoT and Blockchain which are filed between the years 2016-2019.
Some of the ways were the distributed architecture of the Blockchain could be really helpful in improving the security patches of IoT network.
The distributed ledger architecture of Blockchain could really help in tracking the values from the sensors without a need of a central sever.
Cloning of nodes with malicious nodes could be prevented easily.
Need of third party platforms for trustful distribution of data could be eliminated, as IoT sensor can exchange data through Blockchain.
Autonomusity could be brought in IoT devices with the implementation of the smart contracts.
A single device failure would not affect the whole architecture if the whole system is implemented with Blockchain’s Peer to peer network.
Intermediary costs could be eliminated with the help of Blockchain architecture.
How companies are implementing Blockchain and IoT together
to make sure that no one can alter the data from the smart devices.
User’s sensitive data which can provide access to smart home and various smart devices such as Biometrics, voice recognition and facial recognition is stored on the Blockchain.
Once the data is saved on Blockchain it can’t be modified and access can be provided to the right person, no trespasser can modify it and crack into it.
Role of Blockchain in other sectors
Blockchain gives it users a trust factor in the form of code, it gives a value and authenticated digital information, which shapes various applications around it including the most significant in financial asset management.
a public-private Blockchain could be used to store the data and making it accessible to the user when a private key in inputted to it.
General Data Protection Regulation (GDPR) policy in European legislation gives the owner of the data more control over it rather than the companies.
Blockchain could be really useful in implementing it, with the use of public-private Blockchain, which gives the user a freedom to manage his data and further he can monetize over it, there are many companies which are collecting the user’s gene data and further can sale it to various companies with the permission of the user and by paying them in the form of crypto currency.
; it could help to run transparent government and polling operations wherein all the votes of each individual could be released in public but under a cryptographic name.
It could help in clean elections without any chance of corruption.
The new upcoming economy trend is one, in which most of the assets are not owned by anyone, but used by everyone on a sharing basis.
Moreover, the sharing economy is based on the consumer trust, top rated products, cars, drivers are the one which are rewarded by the system and the one factor based on which consumer chooses from.
would give you an insight to it.
Redistribution and illegal use of creative works is a serious problem to the owner of the copyrights.
The illegal use of creative works affects the market image of the owner, and most time the plagiarized content is in digital form and is available on the internet easily.
Blockchain could be a smart solution to it for preventing the illegal and improper use of intellectual property assets such as copyrights.
magazine which would give you more insight to this field.
between intra- and inter- institute verification system.
A smart contract is a digital document intended to verify, facilitate or enforce a negotiation or the statement held by a contract.
The difference between a traditional contract and a smart contract is that smart contracts are withheld and enforceable without third party interference.
in a transparent and a conflict-free way while avoiding the services of third parties such as court or a notary.
A simple example of it is when someone lends a house to a person then that person pays by crypto currency to the system and generates a digital contract.
When the owner of the house lends you the digital Key of the apartment which is valid for the date mentioned on the contract, not before that, and when your lease is over you can regenerate it by paying the system, otherwise your key would be held invalid.
Since its advent Blockchain has seen a huge increase in attention and is evolving into different technological sectors.
For its further development we have still wait to know what future holds for it.
tutorial/transformerless-led-driver-circuit-for-low-cost-led-bulb-designs
Transformerless LED Driver Circuit for Reliable Low Cost LED Bulb Designs
to power four LEDs (in series) which can provide 200 Lumens operating at 13.6V and consuming around 100-150mA.
Before we move any further it is very important to make sure that you work with extreme caution around AC mains.
The circuit and details provided here was tested and handled by experts.
Any mishaps can lead to serious damages and might also be lethal.
Work at your own risk.
You have been warned.
Transformerless Power Supply circuit
using a switching IC.
Drawback of Capacitor Drop Transfromerless Power Supply Circuit
to drop the input voltage.
, where the enclosure is made with hard plastic, and no circuit part is exposed for user's interaction once installed.
The problem with these types of circuits is that if the power supply unit fails, it could reflect the high input AC voltage across the output and that can become a death trap.
So, the question is, is there any solution that can be cheaper, efficient, simple, and smaller in size along with all protection circuits to make a non-isolated AC to DC high power LED driver circuit? The answer is yes and that is exactly what we are going to build in this tutorial.
Selecting the right LED for your LED bulb
The first step in designing an LED bulb driver circuit is deciding on the load i.e the LED that we are going to use in our bulbs.
The ones that we use in this project are shown below.
will flow through each leds.
Here is the schematic of LEDs in series ᾍ
LNK304 - LED Driver IC
It can successfully provide the required load for this application along with auto restart, short-circuit, and thermal protection.
The features can be seen in the below image ᾍ
Selecting the other components
It may increase the production cost, but in the end, the design tradeoffs also matter for proper power delivering across the load.
The schematic diagram without values can be seen in the below image, now let’s discuss how to select the values
is used where two electrolytic capacitors are required along with an inductor.
This will rectify the DC and also reduce the EMI.
The capacitors values selected for this application is a 10uF 400V electrolytic capacitors.
The values need to be higher than the 2.2uF 400V.
For cost optimization purposes, 4.7uF to 6.8uF can be the best choice.
For the inductor, more than 560uH is recommended with 1.5A of the current rating.
Therefore, C1 and C2 are selected to be 10uF 400V and L1 as 680uH and a 1.5A DB107 diode bridge for DB1.
The bypass pin needs to be connected with the source by a 0.1uF 50V capacitor.
Therefore C3 is 0.1uF 50V ceramic capacitor.
D1 is needed to be an ultrafast diode with a reverse recovery time 75 ns.
It is selected as UF4007.
, the resistor value is selected based on the below formula
Vout = (Source voltage x R2) / (R1 + R2)
In our caseVout is 1.635V, the Source voltage is 13.6V.
We selected the R2 value as 2.05k.
So, the R1 is 15k.
Alternatively you can use this formula to also calculate the source voltage.
The capacitor C4 is selected as 10uF 50V.
D2 is a standard rectifier diode 1N4007.
The L2 is the same as L1 but the current can be less.
L2 is also 680uH with 1.5A rating.
The output filter capacitor C5 is selected as 100uF 25V.
R3 is a minimum load which is used for regulation purposes.
For zero load regulation, the value is selected as 2.4k.
The updated schematic along with all values is shown below.
Working of Transformerless LED Driver Circuit
After getting the rectified DC, the power processing stage is done by the LNK304 and D1, L2 and C5.
The voltage drop across the D1 and D2 is almost the same, the capacitor C3 checks the output voltage and depending on the voltage across the capacitor C3 is sensed by the LNK304 using the voltage divider and regulating the switching output across the source pins.
Building the LED Driver Circuit
r using the resonant frequency method.
The above image shows that the Inductors are checked and the value is more than the 800uH.
It is used for L1 and L2.
A simple copper clad board is also made for LEDs.
The circuit is constructed in a breadboard.
Testing the LED driver Circuit
The circuit is first tested using a VARIAC (Variable Transformer) and then checked in universal input voltage that is 110V/220V AC voltage.
The multimeter on the left is connected across the AC input and another multimeter on the right is connected across a single LED to check the output DC voltage.
can be found below.
article/how-5g-is-becoming-an-important-technology-for-iot
How 5G is becoming an Important Technology Ingredient for IoT
Internet and connectivity are taking center stage, not just in the industrial environment but also among individualsᾠpersonal spaces.
With internet becoming the prime ‘ingredientᾠin nearly every electronic system, the importance of connectivity has been amplified to a whole new level, today.
of mobile networks marks a milestone.
5G is no more the concept from future in most developed countries, and it is soon likely to make a foray into developing nations.
).
are evolving across the world, the introduction to 5G is expected to ingrain a sea change in the world of IoT.
, which is expected to accelerate the 5G rollout in the upcoming years, shaping a new future for IoT as well as a connected world.
This article sheds lights on how 5G is influencing IoT to create a better-connected world through advanced electronics.
Importance of 5G for IoT
Though 5G is not indispensable for the implementation of IoT in various applications, its emergence is tapping into the complete potential of this technology.
The convergence of 5G with IoT is facilitating the process of ultimate connectedness of the world into fruition.
will improve the reliability of IoT applications, as it will enable innovative features such as the real-time monitoring facility, in most of the ‘smartᾠand ‘intelligentᾠdevices.
in various processes such as monitoring, sensing, as well as metering.
While IoT is gaining popularity among individuals, owing to its benefits in streamlining various operations—mainly related to safety, security, power efficiency, and healthG is emerging as a new technological, functional ingredient for IoT to boost its connectivity, reliability, and speed.
mMTC: A New Buzzword in the World of IoT and Smart Cities
Connectivity is becoming one of the most important indicators of measuring development for all the economies in the world, as limited network availability and reliability has stunted growth for dense urban areas, especially in developing nations.
Poor connectivity and inability to meet specific power requirements of various electronic devices has been restricting the penetration of advanced applications of IoT in most developing countries.
applications.
trend.
and the Category M1 (Cat M1) technology.
When NB-IoT devices in most industrial environments are supported by 5G networks, smart manufacturing facilities and smart city projects will be able to reap benefits of uRLLC and mMTC.
How will 5G Impact IoT Applications in Industrial Environment
—the need for boosting connectivity and speed of data transfer will surge rapidly, and 5G is highly likely to replace all the conventional modes of networking.
benefits of 5G incorporated in IoT designs, and can transform the operational model for many businesses in the future.
with the convergence of 5G with IoT.
Though the worldwide penetration of 5G is still a concept from the future, most countries are focusing on entering into the world with better connectivity and incredibly superior modes of communication, which is mainly due to the major impacts of 5G on IoT.
article/what-is-bleeder-resistor-and-where-it-is-used
What is Bleeder Resistor and where it is used?
Whybleeder resistors are used?
Lets consider a simple circuit as shown below.
Here a capacitor is attached in parallel with main circuit.
Now when the power supply is ON, the capacitor will get charged to its peak value and remains charged even after the power is turned OFF, and that can be a big hazard if you are working with really high valued capacitors.
This capacitor can give a high shock.
So to prevent this, a resistor of a high value is connected in parallel with the capacitor, so that it may get discharged completely into the resistor.
Voltage regulation is the ratio of difference between full load voltage and no load voltage to the full load voltage i.e.
it indicates that if a system can provide constant voltage for different loads.
The formula for voltage regulation is given as:
VR = |Vnl| - |Vfl| / |Vfl|
Here,
= No load voltage
= Full load voltage
So if VR near to zero means the voltage regulation is good.
Lets say, If we connect the load voltage then the full voltage will 23.5V and if we remove the voltage then the voltage due to bleeder resistor is 22.4V so the voltage difference between them is 1.1V which is quiet low.
Now if we do not connect the bleeder resistor then this difference will be high and hence the regulation will be low.
.
How to Choose the Bleeder Resistor?
One has to compromise between power consumption and the speed of bleeder resistor.
A small valued resistor can provide high speed bleeding but the power consumed is higher.
So it is up to the designer that how much manipulation does he wants.
The resistor value must be high enough to not interfere with power supply and at the same time low enough to discharge the capacitor quickly.
The formula to calculate the value of bleeder resistor is given as:
R = -t/C*ln(Vsafe/Vo)
Here
t is the time taken by the capacitor to discharge through bleeder resistor
R is the resistance of bleeder resistor
C is capacitance of the capacitor
is the safe voltage up to which it can be discharged
is initial voltage of the capacitor
but if we put zero there, then it will take infinite time to discharge.
So, it’s a hit and trial method.
Put the safe voltage and the time with which you want to discharge the capacitor and you’ll get the value of bleeder resistor.
To manipulate the power too use the below formula:
P = Vo2/R
Here P is the power consumed by the bleeder resistor
is the initial voltage in capacitor
R is the resistance of bleeder resistor
So after deciding how much power consumption by the bleeder resistor can be, we can find the desired value for bleeder resistor using both the above equations.
is 10V.
If the discharge time we want is 4 seconds then the bleeder resistor value should be 997877.5 ohms or below than that.
You can use a near valued resistor to this value.
The power consumption will be 2.25W.
The resistor value is calculated by putting the capacitance, initial voltage, safe voltage and discharge time in the first formula.
Then put the value of initial voltage and the resistor value in second formula to get the power consumption.
The resistor value can also be found in the reverse format i.e.
first decide that how much power do you want it to consume and then put the power and initial voltage in second formula.
So, you will get the resistor value and then use it in first formula to calculate the discharge time constant.
article/how-iot-is-transforming-food-industry-and-improving-food-safety
How IoT is Transforming Food Industry and Improving Food Safety
So here are few ways for improving Food industry using IoT.
1. Enhancing Quality Assurance
that customers can scan to confirm the safety of the product.
This creates an assurance between the consumer and the manufacturing company that the food is safe for consumption.
2. Use of Smart Inventory Sensors
to monitor the stock.
The sensor sends alerts when the stock runs low.
Companies can further integrate Artificial Intelligence with IoT to understand consumer purchasing habits that will facilitate in future planning.
3. Use of Drones to Manage Plantations
where the crops are watered automatically by sensing the soil moisture.
4. Automation
, give info regarding the planting and harvesting progress, and provide details regarding the current yield.
The autonomous tractors save approximately 50% of the labor cost.
, which helps to keep the food safe.
5. IoT has Enhanced Precision Farming
in the wake of adverse climate change.
6. Collaboration between Food and Agricultural Stakeholders
among the relevant stakeholders.
Easy access to data will help in making sound food policies to enhance food safety.
7. Supply Chain Transparency
IoT helps to reveal laxity in the supply chain process, which allows manufacturers to make the appropriate changes to meet the required standards.
8. Improved Food safety
The food supply chain companies can utilize IoT technology to comply with the set global food safety regulations.
Food manufacturing and processing companies can use IoT technology to ensure they become compliant with the Hazard Analysis and Critical Control Points (HACCP).
9. Enhanced Operational Efficiency
by automating the process of food quality reporting.
tutorial/bi-directional-logic-level-controller-using-mosfet
Bi-Directional Logic Level converter using MOSFET
Back in the ENIAC era, computers were more analog in nature and used very few digital ICs.
Today an average Joe’s computer works with multiple voltage levels, people who had seen the SMPS of a CPU would have noticed that your computer requires ±12V, +5V and +3.3V to operate.
These voltage levels are very important for a computer; a specific voltage determines the state of the signal (high or low).
This high state is accepted by the computer as binary 1 and the low state as binary 0.
Depending on the 0 and 1 condition computer produces data, codes, and instructions to provide required output.
which will come in handy for your circuits designs.
High-Level and Low-Level Input voltage
).
Above example is true for 5V logic level microcontrollers but 3.3V and 1.8V logic level microcontrollers are also available.
In such type of microcontrollers, the logic level voltage range will vary.
You can get the relevant information from the datasheet of that particular controller IC.
When using a voltage level converter, care should be taken that the high voltage value and low voltage value is within the limit of these parameters.
Bi-directional Logic Level Converter
For the Bi-directional level converters, each voltage domain not only has input pins but also has the output pin.
For example if you provide 5.5V to input side it will convert it to 3.3V on the output side, similarly if you provide 3.3V to the output side, it will convert it to 5V on the input side.
Simple Bi-directional Logic Level Converter
A simple bi-directional logic converter circuit is shown in the below image.
but it will introduce voltage loss.
MOSFET or transistor-based logic level converters are professional, reliable, and safer to integrate.
Due to the lowest part count, it is a cost-effective solution too.
Depending on the above circuit, a simple 3.3V to 5V bi-directional logic converter will be constructed.
5V to 3.3V Level Converter using MOSFET
can be seen in the below image -
can be interchangeably used as Input and Output pins.
The components used in the above circuit are
R1 - 4.7k
R2 - 4.7k
Q1 - BS170 (N channel MOSFET).
The circuit construction consists of two pull up resistors 4.7k each.
Drain and the source pin of MOSFET are pulled up to the desired voltage level (in this case 5V and 3.3V) for the low to high or high to low logic conversion.
You can also use any value between 1k to 10k for R1 and R2 since they acts only as pull up resistors.
For the perfect working state, there are two conditions that need to be met while constructing the circuit.
The first condition is, the low level logic voltage (3.3V in this case) requires to be connected with the MOSFET’s source and the high level logic voltage (5V in this case) must be connected to the drain pin of the MOSFET.
The second condition is, the gate of the MOSFET needs to be connected to the low voltage supply (3.3V in this case).
Simulationof Bi-Directional Logic Level Converter
the Logic input pin is shifted between 5V and 0V (ground) and the logic output is obtained as 3.3V and 0V.
Similarly during the low level to high level conversion the Logic input is between 3.3V and 0V is converted into Logic output of 5V and 0V as shown in the below GIF image.
Logic Level Converter Circuit Working
After fulfilling those two conditions, the circuit works in three states.
The states are described below.
When the low side is in logic 1 or high state (3.3V).
When the low side is in logic 0 or low state (0V).
When the High side changes the state from 1 to 0 or high to low (5V to 0V)
When the low side is high, that means the source voltage of the MOSFET is 3.3V, the MOSFET does not conduct due to the Vgs threshold point of the MOSFET is not achieved.
At this point the gate of the MOSFET is 3.3V and the source of the MOSFET is also 3.3V.
Therefore, Vgs is 0V.
The MOSFET is off.
Logic 1 or high state of the low side input reflects on the drain side of the MOSFET as a 5V output via the pullup resistor R2.
In this situation, if the low side of the MOSFET changes its state from high to low, the MOSFET starts to conduct.
The source is in logic 0, hence the high side also became 0.
Those above two conditions successfully convert low voltage logic state to a high voltage logic state.
Another working state is when the high side of the MOSFET changes its state from high to low.
It is the time when the drain substrate diode starts to conduct.
The MOSFET low side is pulled down to a low voltage level until the Vgs cross the threshold point.
The bus line of both low and high voltage section became low at the same voltage level.
Switching speed of the Converter
Another important parameter to consider when designing a logic level converter is the Transition speed.
Since most logic converters will be used between communication buses like USART, I2C etc it is important for the logic converter to switch fast enough (transition speed) to match up with the baud rate of the communication lines.
So our MOSFET here requires 10nS to turn on and 10nS to turn off, meaning it can turn on and off 10,00,000 times in one second.
Assuming that our communication line is operating at a speed of (baud rate) 115200 bits per second, then it means it turns and off only 1,15,200 in one second.
So we can very well use our device for high baud rate communication as well.
Testing your Logic Converter
The following components and tools are required to test the circuit -
Power supply with two different voltage output.
Two multimeters.
Two tactile switches.
Few wires for connection.
The schematic is modified to test the circuit.
, the low side of the MOSFET changes its state from high to low and the logic level converter is working as a low voltage to high voltage logic level converter.
, high side of the MOSFET changes its state from high to low and the logic level converter is working as a high voltage to low voltage logic level converter.
The circuit is constructed in a breadboard and tested.
The above picture is showing the logic state across both sides of the MOSFET.
Both are in Logic 1 state.
The full working video can be seen in the below video.
Limitations of Logic Level Converter
can be used in this circuit is dependent on the MOSFET's specification.
Also, the minimum logic voltage is 1.8V.
Less than 1.8V logic voltage will not work properly due to the Vgs limitation of the MOSFET.
For lower voltage than 1.8V, dedicated logic level converters can be used.
Importance and Applications
As discussed in the introductory part, incompatible voltage level in digital electronics is a problem for interfacing and data transmission.
Therefore, a level converter or level shifter is required to overcome the voltage level related errors in the circuitry.
, need level converters for communication purposes with a microcontroller.
Popular Logic Level Converter ICs
and few other microcontrollers earlier to interface a microcontroller with computer.
There are different requirements also exist depending on the very low voltage level conversion, conversion speed, space, cost, etc.
There are lots of ICs in this segment which offers a single bit to 4-bit supply bus transition along with additional features.
It uses the same conversion topology using MOSFET.
The pin diagram can be seen in the below image.
The converter supports separate enable pin that can be controlled using microcontrollers which is an added feature.
on I/O and VCC lines.
The typical schematic can be seen in the below image.
The above schematic is showing a circuit which is converting the 1.8V logic level to a 3.3V logic level and vice-versa.
System controller that can be any microcontroller unit is also controlling the EN pin.
So, this is all about Bi-directional logic level conversion circuit and working.
article/electromagnetic-compatibility-in-electric-vehicles
Electromagnetic compatibility in Electric Vehicles - Sources of EMI and Guidelines to reduce it
, high-power cables distributed around the vehicle and chargers, all these are working at high power and frequency levels which causes the emission of high-level low-frequency EMI.
are in hundreds of volts so that current levels will be in hundreds of Amperes, which causes stronger magnetic fields
Nissan LEAF is having 125 kW rear wheel drive works on 400 VDC
BMW i3 is having 125 kW rear wheel drive works on 500 VDC
Tesla model S is having 235 kW Rear wheel drive works on 650 VDC
Toyota Prius (3rd gen.) is having 74 kW Front wheel drive works on 400 VDC
Toyota Prius PHV is having Front wheel drive rated 60 kW works on 350 VDC
Chevrolet Volt PHV is having Front wheel drive rated 55 kW (x2) works on 400 VDC
of all these subsystems and components to ensure components safety along with living beings safety.
Terms & Definitions related to EMC and EMI
represents electromagnetic emission, susceptibility, Immunity and coupling issues.
of a device indicates it’s vulnerability to unwanted emissions and interference which causes the malfunction or break down of device.
If a device is more susceptible means it is less immune to electromagnetic interference.
of a device means it’s ability to operate normally in the presence of electromagnetic environment without experiencing interference or break down due to the electromagnetic emissions from another electronic device.
means mechanism of one device’s emitted electromagnetic field reaching or interfering with other device.
Sources of Electromagnetic Interference (EMI) in EV
Power Converters are known to be the main source of electromagnetic interference within electric drive systems.
These are having high speed switching device, e.g.
conventional Insulated Gate Bipolar Transistors (IGBT) work at frequencies ranging from 2 to 20 kHz, fast IGBTs can work up to 50 kHz and SiC MOSFETs can even work frequencies above 150 KHz.
Electric Motors which are operating at high power levels causes electromagnetic emissions and it act as path for EM noise through it's impedance.
And this impedance changes as a function of frequency.
As electric motor drives use power inverters with high-speed PWM switching operation, surge voltages are occurring at the motor terminals, which cause the radiated EM noise.
And the shaft current may cause damage of motor bearings and malfunction of the vehicle controller.
As traction batteries are distributed, the currents in the batteries and in the interconnectors become a significant source for EMF emission and these are main part of the path for EMI.
Shielded and Unshielded Cables carrying high level current between various subsystems like battery to power converter, power converter to motor etc, in the EV causes stronger magnetic fields.
As available space in EV for wiring harness is limited, high voltage and low voltage cables are placed near to each other causes electromagnetic interference between them.
The battery chargers and the wireless charging facilities are the major external EMI sources apart from EV internal EMI source.
When wireless power technology applied to charge the EV, a strong magnetic field in the range of several tens to hundreds of kilohertz produces to transfer several KWs to tens of KWs of power.
EMI impact on Electric Vehicle Electronic Components
EMC Standards for Electric Vehicles
-SA), the European Community (EC) and the United Nations Economic Commission for Europe (UNECE).
specifies the general conditions, guidelines and basic principles to test the vehicle to determine the immunity of ICE and electric vehicles over electrical disturbance narrowband radiated EMF.
specifies the general conditions, guidelines and basic principles to test the component to determine the immunity of electronic components of ICE and electric vehicles over electrical disturbance narrowband radiated EMF.
specifies the limits and methods of measurement to test the radiated electromagnetic emissions from electric vehicles, ICE vehicles and boats.
specifies the limits and methods to measure the radio disturbance characteristics and the procedure to test the vehicle to determine the RI/ RE levels for the protection of receivers used on board vehicles.
specifies performance levels and Methods of measurement of EMC of vehicles and devices (60Hz-18GHz).
specifies test limits and methods of measurement of radio disturbance (emission) characteristics of vehicles, Motorboats, and spark-ignited Engine Driven Devices.
specifies test limits and methods of measurement of radio disturbance characteristics of vehicles and devices, broadband and narrowband, 150 KHz to 1000 MHz.
specifies performance levels and methods of measurement of magnetic and electric field strength from electric vehicles, 9 kHz to 30MHz.
specifies vehicle electromagnetic immunity-Off vehicle source.
specifies vehicle electromagnetic immunity-bulk current injection.
specifies vehicle electromagnetic immunity-electrostatic discharge which will be done in shielded room.
specifiesvehicle electromagnetic immunity-power line magnetic fields.
specifies method of measurement of radiated broadband emissions from vehicles.
specifies method of measurement of radiated narrowband emissions from vehicles.
specifies method of testing for immunity of vehicles to electromagnetic radiation.
provides requirements for Electromagnetic Compatibility in Automotive Vehicles.
explains method of measurement of radiated broadband electromagnetic emissions from vehicles.
explains method of measurement of radiated narrowband electromagnetic emissions from vehicles.
explains method of testing for immunity of vehicles to electromagnetic radiation.
explains method of measurement of radiated broadband electromagnetic emissions from electrical/electronic sub assemblies.
explains method of measurement of radiated narrowband electromagnetic emissions from electrical/electronic sub assemblies.
Limits to Exposure of Electromagnetic Fields to Humans
Electric vehicles produce non-ionizing electromagnetic radiations which don’t effect on human health for short time exposure.
But for long time exposure if the radiated magnetic field is more than the standard limits, it effects human health.
So, while designing electric vehicle the hazards with magnetic field exposure must be taken into account.
Electromagnetic exposure to passengers affects by different configurations, power levels and topologies of electric vehicle like front wheel drive or rear wheel drive, battery placement and the distance between power equipment to the passengers etc,.
By considering possible harmful effects of human exposure to electromagnetic fields international organizations, including the World Health Organization (WHO) and the International Commission for Non-ionizing Radiation Protection (ICNIRP), EU directives, IEEE have specified limits to maximum permissible magnetic field exposure to public.
Frequency (Hz)
)
Magnetic flux density B(T)
< 0.153 Hz
0.153 -20Hz
/f
18.1 x 10-3/f
20- 759 Hz
719
759 Hz - 3KHz
5.47 x 105/f
/f
means people who are exposed to EMF while doing their regular job activities.
means the rest of public other than occupational exposed to electromagnetic fields
have no adverse health effect under normal working conditions and for persons not having any active Implanted Medical Device or being pregnant.
These are corresponds to field strength.
causes some effects exposed to these levels.
These are corresponds to the maximum directly measurable field.
Basically Action value is higher than Orientation value.
Occupational public exposure values are higher than those for the general public exposure level.
Electromagnetic Compatibility Tests
Laboratory tests and road tests are performed on electric vehicle to assess EMC.
These tests consists emissions, susceptibility and immunity tests.
are done to characterize the magnetic field emissions and susceptibility from all of the on-board electrical equipment in an EMC test chamber.
These chambers are anechoic and reverberation types.
, antennas are used as transducers.
Radiated emissions are measured in all directions around the device under test (DUT).
uses high-powered source of RF EM energy and a radiating antenna to direct the electromagnetic energy to the DUT.
While doing test on electric vehicle except the device under test (DUT) everything will be switched off and then the magnetic field will be measured.
These tests will be performed on straight road where the magnetic fields due to earth is constant and in some cases on steep slope roads.
While doing on road tests we have to identify the external magnetic perturbations from external sources like railway lines, manhole covers and other cars, power distribution equipments, high-voltage transmission lines and power transformers.
Design guidelines for better EMC and to lower the EMI
DC cables carrying high currents should be made in twisted form so that the current in this cable flow in opposite direction results in minimization of EMF emission.
Three phase AC cables should be twisted and need to place as close as possible to minimize EMF emission from them.
And all these power cables need to place as far away as possible from passenger seat region.
And these connections should not form a loop.
If the distance between passenger seats and cable is less than 200 mm, shielding must be adopted.
Motors need to be placed farther away from passenger seat area and the rotation axis of motor should not point towards passenger seat area.
As steel has better shielding effect, if weight permits instead of aluminium, steel metal housing need to be used for motor.
If the distance between the motor and passenger seat area is less than 500mm, shielding like steel plate need to be employed between the motor and passenger seat area.
Motor housing should be grounded to chassis properly to minimize any electrical potential.
To minimize the cable length between the inverter and motor they mounted as close as possible to each other.
To suppress the surge voltage, shaft current and radiated noise an EMI noise controller should be attached to the motor terminals.
A digital active EMI filter needs to be integrated into the digital controller of a DC-DC converter to charge the low voltage battery and to provide significant EMI attenuation.
To suppress the EMI during wireless charging, resonant reactive shielding has been developed.
Here the leakage magnetic field passes through the resonant reactive shield coils in such a way that the induced EMF in each shield coil can cancel the incident EMF and the magnetic field leakage can be effectively suppressed without consuming additional power.
Conductive shielding, magnetic shielding and active shielding technologies have been developed to shield the electromagnetic field emission from the WPT system.
An EMI noise controller has been developed for electric vehicles, which is attached on the motor terminals to suppress the surge voltage, shaft current and radiated noise.
article/narrow-band-nb-iot-next-level-communication-network-for-internet-of-things
Narrow Band (NB) IoT ᾠThe next level Communication Network for Internet of Things
Among the two networks, NB-IOT will be the focus of this article.
What is NB-IOT?
The network is an LPWA (Low Power Wide Area) network known as Narrow Band, specially designed for IOT devices that would work on low frequencies & consume less power.
The NarrowBand-IOT is a network technology developed by 3GPP working with big telecom giants like Huawei, Qualcomm, Ericsson & Vodafone.
Why NB-IOT?
All the IOT devices already developed or to be developed need to work 24/7 to send data & keep the user updated.
These long hours of work requirement mean consuming more power.
Also with consuming more power, the data is to be sent on high bandwidths for billions of devices connected.
All of which would result in
Long-range bandwidth usage,
Less battery life
More cost with the current LTE networks
So, to connect all the billions of devices & achieve more reliability & quality service, the NarrowBand came into the picture, which leads to the benefits of NB-IOT.
NB-IOT Benefits
The NB-IOT devices will be consuming less power because they will be transferring a small amount of data at low data rates of around 100 ᾠ150 kbps.
The devices connected will be having a loop to send data after every particular amount of time, which means that power would be saved all the time except when for a few seconds the data is being sent.
Only the power consumed will be by the sources of power & internet device.
Resulting in very less amount of power consumed than an LTE IOT device.
Since the device will be consuming low power & sending data at low frequency, the cost of the product electronics will get low for the device.
The circuits would be also less completed & as a result, the chips that would be built for NB-IOT will be less costly & the product's overall cost will reduce too.
The band spectrum use for NB-IOT is licensed by 3GPP and which would always provide a quality M2M (machine to machine) communication.
Resulting, the users of NB-IOT will get a reliable service.
The Applications of IOT are well known to the people interested in IOT but with IOT using NarrowBand, the number of NB-IOT applications will increase in huge numbers.
The device can also be used for communication between machines that are Underground or where normal mobile network coverage isn't possible to receive.
With that, it could be used for House, Industrial, Commercial applications.
Also, Smart City application would get a great hand from the NB-IOT technology.
The NB-IOT network is a licensed network & which means the data transferred is secure.
It would provide all the security features as that of the LTE network which is already the tried & trusted security for the users, providing the user's data authentication, integrity & confidentiality worldwide.
Electronics in the IOT device would consume less power than it would be consumed by an LTE mobile device.
So, comparatively the battery life for the device will be more.
It is said that the battery life may even last up-to or more than 10 years for any single IOT device.
The transmission of data for the NB-IOT network will be two ways i.e.
the data could be sent & received and the network has RF bandwidth of 200 KHz.
The NB-IOT network could be easily deployed into the existing cellular network architecture which means that the mobile devices can easily connect with the NBIOT devices, with about a connection of around 1million IOT devices per Cell phone.
So, the data of 1 million IOT devices could be accessed by just 1 mobile phone making the connectivity more in numbers.
With all the above features, the NB-IOT would come up with one more feature i.e.
large coverage area.
The maximum area that could be covered by the NB-IOT devices will be around 20 ᾠ25 Kms.
Examples of NB-IOT
NB-IOT application developed by Huawei & China Unicom.
The Intelligent parking system helps with the free parking space availability for the customers, time count of parking & calculating the cost to be paid by the customer.
With all that the system works reliably by consuming low power.
Many houses/society have a basement and since it is underground it needs electricity all the time.
But using the NB-IOT technology, the lights of the basement will turn on only when someone is present instead of manually turning it ON for long hours.
NarrowBand (NB) - IOT in India
The large telecom companies of India are competing with each other on the running 4G technology & all of them are planning to bring the NB-IOT network soon in India with the 5G network.
The telecom giants like JIO, Airtel & Vodafone are all having plans to get hands-on with NB-IOT technology & expand their 5G network across India soon.
Though they have already launched their plans or products for
IOT devices, in the year 2020 they all will be ruling on the NB-IOT technology too.
With the advancement in technologies like IOT & emerging new networks like NBIOT, the future will be a great change in terms of the way people work now & will be working then.
Technology would ease & benefit the humans in many ways.
article/lithium-ion-battery-manufacturing-3-ways-to-minimize-the-cost
Lithium Ion Battery Manufacturing: 3 Ways to Minimize the Cost
, as margins are cut to the bone in this landscape.
1. Maintaining Competitive Prices by Mitigating Raw Material Costs
, through the development of new anode and cathode active materials and innovative methods of material-processing techniques to address the need to control cost and introduce safer and reliable batteries.
can be an important catalyst in minimizing the “raw materialᾠcost for lithium-ion batteries.
2. Adopting Advanced Technologies Maximize Business Productivity and Mitigate Costs
—emphasizes the adoption of advanced technologies for implementing factory automation and digitalization of manufacturing operations to ensure efficient mass production and economic success.
, lithium ion battery manufacturers can overcome this challenge.
Implementing automation and digitalization solutions can help businesses to trigger the productivity and efficiency of their li-ion battery manufacturing plants and mitigate manufacturing expenses by reducing downtime and processing costs.
in a lithium ion battery manufacturing plant.
Simultaneous engineering or concurrent engineering solutions are also gaining immense popularity among Li-ion battery manufacturers, as these solution can help in producing better battery module designs and further boost efficiency of a lithium ion battery manufacturing plant.
In addition, the adoption of high-tech welding machines that are compatible with next-generation automation technologies will reach new heights with the rising trend of Industry 4.0 in this landscape.
will become an integral part of data management processes as well as maintenance monitoring operations in lithium ion battery manufacturing businesses.
Manufacturers, who will realize the power of technologically strong automation and digitalization solutions, will lead the pack in the world of li-ion battery manufacturing.
3. Favourable Government Policies and Incentives for Lithium Ion Battery Manufacturing Businesses
Stakeholders have a wide range of favourable geographical locations with best business case of setting a lithium ion battery manufacturing plant.
However, the European Union (EU), and emerging economies in Asia Pacific, such as China and India are among the most popular regions where governing bodies are creating suitable environment for lithium ion battery businesses to foster.
) was recently approved with a total outlay of US$ 1.45 billion to foster e-mobility in the country.
By developing various strategic action plans and offering incentives for boosting the adoption of battery electric vehicles, various governing bodies are creating positive growth environment for lithium ion battery manufacturers.
Changing geopolitical factors and regulatory frameworks in favour of electric vehicles will prove instrumental in cost reduction for businesses in setting up a new lithium ion manufacturing plant in these regions in the coming future.
article/how-to-deal-with-iot-security-challenges-for-smart-iot-devices
How to Deal with Security Challenges for Smart IoT Devices
, Hangzhou Xiongmai Technology; a Chinese company was forced to recall millions of surveillance devices after a security vulnerability caused an attack on Dyn’s servers that houses Twitter and Netflix.
Cybersecurity is perceived as a problem for big corporations.
As a result, security details are not a priority when it comes to the manufacturing of devices some years back.
However, recent developments indicate that device manufacturers are prioritizing security in the life-cycle of manufacturing IoT devices.
IoT devices are released in millions and as consumers rush to purchase these devices, very few customers follow-up with device manufacturers to install software upgrades.
Also, much of these devices use device-specific software with low usability making it difficult for users to update the software without an expert.
that other are not compatible or supported by the existing enterprise security tools.
As a result, enterprise security tools such as firewalls and IDS do not secure these industrial specific protocols.
Due to the interconnection of these devices, a compromise on the IoT device protocol makes the whole network vulnerable.
Due to specialization, different manufacturers specialize in manufacturing a specific component of an IoT.
Majority of these manufacturers are located in different countries, thus following industrial standards set in those countries.
As a result, the components used to make a single IoT device might end up having different security standards.
This difference in security standards might lead to incompatibility or induce vulnerability.
, and smart utility grids all rely on IoT.
Due to the crucial role played by these infrastructures, the security risk involved is also high due to the high interest by hackers.
What should users do to secure IoT Devices?
Users have a critical role in enhancing the security of IoT devices.
Some of these responsibilities include;
released a report indicating that 15% of users use default passwords.
What is not known to many users is that the majority of these passwords can be accessed using any search engine.
Users should further implement strong and secure passwords to authenticate their devices.
the majority of IoT cyber-attacks occur due to failure by users to update the device firmware regularly.
Where else there are devices that update automatically, other devices require manual update.
Updating software helps to patch security vulnerabilities and get better performance from the upgraded software.
Majority of smart devices are designed to search and connect to any networks automatically.
Connecting to an open network, especially in public places, is not safe and might expose your device to cyber-attacks.
The best solution is to turn off automatic internet connection.
Users should also switch off Universal plug and play.
UPnP helps IoT devices automatically to connect to each other.
Hackers can exploit UPnP by discovering these devices and connecting to them.
Network segregation is very crucial even in an organization.
Giving access to visitors to your network allows them to access and share resources with the connected devices.
Therefore, to avoid exposing your devices to insider threats and untrustworthy friends, it is essential to create a separate network for your guests.
IoT security strategies
Developers and device manufacturers should adopt Application performance indicators (API) as a strategy of securing communication and data exchange between IoT devices and servers.
Developers and manufacturers of IoT devices and software should make security an integral part of the design and development process.
Factoring security during the initial development process guarantees secure hardware and software.
Device manufacturers should adopt strategies to ensure devices are tamper-proof.
Endpoint hardening guarantees that devices operating under harsh weather conditions can function even with minimal monitoring.
One strategy of enhancing IoT security is through the use of PKI and 509 digital certificates.
Establishing trust and control among connecting devices is crucial for network security.
Digital certificates and PKI guarantees secure distribution of encryption keys, data exchange, and identity verification over the network.
to monitor each connected device.
An identity management systems assigns a unique identifier to each IoT device facilitating monitoring of the device’s behaviour making it easier to enforce the appropriate security measures.
IoT devices do not have enough memory or processing power to offer the required security.
Using security gateways like Intrusion Detection Systems and firewalls can help offer advanced security features.
IoT is an emerging field, and as a result, constant training of the security team is essential.
Development and security team needs to be trained on emerging programming languages and security measures.
The security and development teams need to work together and harmonize their activities and ensure security measures are integrated during development.
IoT Devices Security Features
Currently, there is no one size fits all security features that can be adopted by device manufacturers.
However, the following security features can facilitate security of IoT devices;
Developers should implement a login mechanism that uses secure protocols such as X.509 or Kerberos for authentication.
implement data and communication encryption to prevent an authorised access.
Current IoT devices are not equipped with IDS that can monitor attempted logins.
Even if a hacker attempts a brute force attack on the devices, there will be no alerts.
Integration of an IDS will ensure that subsequent failed attempted logins incidences or other malicious attacks are reported.
Tampered IoT devices especially those under minimal supervision are vulnerable to cyber-attacks.
Latest processor designs are integrated with tamper detection sensors.
These sensors can detect when the original seals are broken.
Integration of a firewall adds an extra layer of protection.
A firewall helps in thwarting cyber-attacks by limiting network access to only the known hosts.
A firewall adds an extra layer of protection against buffer overflow and brute force attacks.
Communication between IoT devices should be encrypted through SSL or SSH protocols.
Encrypting communication helps to prevent eavesdropping and packet sniffing.
Cyber-attack is one of the major hindrances to the success of IoT technology.
Enhancing security requires all stakeholders to work in harmony to ensure the set standards are implemented and adhered to.
The relevant bodies should introduce IoT industrial specific standards that are compatible and supported by other industry standards to enhance the operability of IoT devices across the board.
IoT International regulations that cut across all countries should be enforced to guarantee seamlessness in the quality of manufactured IoT devices.
Stakeholders should sensitize users on the need and ways of securing their devices and networks against cyber-attacks.
article/how-optic-fiber-networks-impact-development-of-iot
How Optic Fiber Networks Impact the Development of IoT?
To resolve, we can turn to Fiber Optics that have the ability to drive the magnanimous data and networking requirement of the Internet of Things.
IoT offers new opportunities for the fiber and optic measurement market which hasn’t undergone a substantial change in the last quarter-century.
The Role of Optic Fibers in IoT
An optical fiber cable receives data in the form of a light beam which travels across its entire length without subjecting to any data loss.
Moreover, by replacing the bulky equipment, the refined fiber network can reduce the cost incurred in logistics, space taken up, and the weight of the material.
This ease of application simplifies data traction, analysis of the existing data while enhancing the security parameters and relevant product automation.
In fact, the Electronic Power Board of Chattanooga, Tennessee, credited with building the United Statesᾠmost famous optic fiber networks elaborated upon the fact that the nation’s first gigabit-speed municipal broadband network was built in the hindsight of supporting the IoT applications.
Optical fiber technology has found its niche in the fields of energy, healthcare, technology, healthcare, aerospace and so on.
In comparison to the traditional transmission, optic fiber gives a better deal in the form of easy remote transmission, diverse capability, multi-faceted, ease of networking, varied parameter and many more.
We can consider an IoT device which cannot be under immense pressure for regular domestic purposes.
However, combine it with scaling requirements of 4K streaming and video conferencing, there is an increased need for enhancing the bandwidth girth.
It is interesting to note that with the progressing demand of 4k streaming, we might leap into the 8k dimension which would require even more bandwidth.
This will change the paradigms of virtual connection and interaction which will further open up the demand for the optical fiber network in the IoT domain as well as improve its connectivity which still needs refinement.
Multiple fiber layers are embedded at the base of the products to offer a seamless collaboration between the sensor and the receiver.
For instance, in the concept of M2M (Machine-to-Machine) such technology can be leveraged to cater to the data request in one equipment, to be transferred to the other bound by encryption to make the switch safe and seamless.
are at play, while in the application layer, data storage, sharing, mining, and computing are at play.
In the network layer, M2M, cognitive radio technology and network context-aware technology are playing the part.
In the perception layer, the technology focuses on data collection, and short communication, which require the optimization of optic fibers.
These fibers can help detect data and transmit them easily to convert them into electrical signals or other procedural culmination.
Industrial Influx
The Oil & Gas industry recently underwent a paradigm shift where it changed its conventional infrastructure to support the ever-growing demand.
IoT is at the forefront and boosting this is Optic Fibers improving operational accuracy and performance.
Since the industry heavily relies on the pipeline module, which is prone to implications of environmental factors as well as mechanical disruption.
In order to avoid the spillage, fiber optics can sense the malady in the pipes in real-time and predict the upcoming situations.
This improves quality of monitoring and shelf-life of the conduits which are otherwise a heady expense.
Not to mention, it also helps save the unnecessary disposal of crude oil which can cost an economy millions of dollars.
Manufacturing industry stands to gain a chance benefit by infusing optic fiber network to control its IoT and optimize the resources as well as slashing down the loss of life, capital and resources.
Consumer IoT
which has a lot of scopes to empower the optic fiber network.
The connectivity and communication across machines for e-health, e-security, and home energy management can be easily improved by deploying optic fibers.
For instance, if we consider healthcare management, this optic fiber connection can easily transmit data from the consumer to the health experts (which can be in the form of an analysis or emergency situation) in real-time and make quick decisions as the situation calls for it.
Summarized Benefits
Rapid data delivery
Reduced cost
Improved efficiency
High capital but high longevity
Conducts only light and therefore, cannot inflict damage
Predictive analysis
Long term benefit
Improved security
Asset tracking
Future Ideations
where more homes will be relying on the annotation of smart devices while raising demands for seamless data transmission across larger distances.
However, due to the high cost of optic fibers, we do have to have a pragmatic eye on the expenses that might arise due to the increased deployment of these fibers.
article/in-display-fingerprint-sensors
In-display Fingerprint Sensors: Types and Working
Smartphones with fingerprint sensors have flooded the market but it hasn’t been long since these sensors started making it to smartphones in the budget segment.
These sensors have become faster and more secure in recent times.
As a result, these sensors are primarily used for smartphone security these days.
Smartphone manufacturers like Xiaomi, Realme and Oppo have made sure that the technology is not just limited to flagship devices.
History
ᾠcame from the likes of Toshiba in 2007.
Later on manufacturers like HTC, Acer and Motorola joined the league with their respective devices.
Apple too joined the party in 2013 with the iPhone 5s getting a fingerprint sensor.
The Cupertino based giant called went on to call it Touch ID.
Since then fingerprint sensor technologies have undergone some major changes.
Tech enthusiasts might know there are three different fingerprint authentication technologies in action.
But the in-display fingerprint technology currently benefits only from the two.
Before we get into the big picture lets us understand the basic technology in works behind.
All fingerprint sensors work by tracking those unique tracking ridges and lines on your fingers.
However, different technologies can be at work in this tracking process including optical scanning, capacitive scanning or ultrasonic scanning.
Types of fingerprint scanners
Optical Scanners (Used in In-display fingerprint sensors)
Ultrasonic Scanners (Used in In-display fingerprint scanners)
Capacitive Scanners
In-display Optical Scanners
(CCD) sits at the heart of an optical sensor, the same sensor which is used in digital cameras and camcorders.
For folks unaware, a CCD is an array of light-sensitive diodes called photosites, which generates electrical signals in response to light photons.
As soon as you place your finger on the sensor, an array of light-emitting diodes (LEDs) light up to illuminate the ridges and gaps and a CCD camera quickly captures an image of the same.
The CCD system generates an inverted image of the finger, with darker areas representing more reflected light (the ridges of the finger) and lighter areas representing less reflected light (the valleys between the ridges).
The image captured is then compared with the stored image.
The optical sensors are easy to fool as the technology used captures a 2D image and a good quality image can possibly breakthrough this security.
It is worth noting that the technology works only with OLED displays, where there are gaps in the backplane.
Initially, in-display fingerprint sensors weren’t as reliable and fast as they are now.
But things have changed in favour of these sensors in recent times.
In-display Ultrasonic Scanners
sensors are the newest of fingerprint technologies being used.
As the name hints, these sensors make use of high-frequency ultrasonic sound to map your fingerprint.
Samsung partnered with Qualcomm to bring the first device with an in-display ultrasonic fingerprint sensor the ‘Galaxy S10/S10+.
The device was also the first to feature Qualcomm’s 3D Sonic sensor which is an iteration of Sense ID.
Qualcomm’s latest ultrasonic technology works through glass that’s up to 800 microns thick.
The company claims a 250-millisecond latency for unlocking which is close to what a capacitive fingerprint scanner can achieve.
The hardware on these scanners consists of an ultrasonic transmitter and receiver.
Scanning process begins as soon as a fingertip is placed on the sensor.
An ultrasonic pulse is transmitted by the transmitter which collides with the ridges and valleys on the fingertip, some of the pulse pressure is absorbed and some of it is bounced back to the sensor.
The amount of absorption and bounce back of the pulse varies with varying fingerprints.
Moving further, a sensor capable of detecting mechanical stress is used to calculate the intensity of the returning ultrasonic pulse at different points on the scanner.
These scanners gain detailed in-depth information, resulting in a detailed 3D replica of the scanned fingerprint.
, which can prevent this technology from working properly.
come equipped with an ultrasonic sensor.
However, there’s still some time until we see this technology penetrating the budget segment.
Capacitive Scanners
Capacitive Sensors are the most widely used sensors these days and can be found on every other device that you come across.
These sensors use capacitors as the core component, which is an electronic component used for storing electrical energy.
The technology is not currently used for in-display fingerprint scanning.
These sensors too scan the ridges and valleys on fingerprints.
However, in this case, electric current is used to collect data instead of light.
An array of capacitors are placed below the scanning surface to collect fingerprint detail.
When a fingertip is placed on the scanning surface the charge stored on the capacitor changes.
This difference in charge is tracked by an op-amp integrator circuit which is further recorded by an analogue-to-digital converter.
are cheap and can be easily integrated by any device.
Algorithm and Cryptography
Scanning is just half the process, having said that it is important to store the data at a secure place.
For this process, a dedicated IC is added to the sensor which deals with interpreting scanned data and further transmitting it to the processor.
The secured place is inaccessible and even rooting cannot help to break in.
Every manufacturer has a different approach and uses different algorithms to identify key fingerprint characteristics.
Generally, these algorithms look for very specific features called minutiae, where the lines in your fingerprint terminate or split in two.
Hence, the scanner can match these minutiae instead of scanning the whole fingerprint again.
Which makes the whole process a tad bit faster.
Moving further, these sensor manufacturers have separate systems for storage.
ARM uses, Trusted Execution Environment (TEE) based TrustZone technology which stores data in a secure place inside the main processor.
Qualcomm on the other side uses Qualcomm Secure Execution Environment (QSEE) for securing private encryption keys and passwords.
These systems might have different names but all of them have a common goal that is protecting data.
Which is better Optical or Ultrasonic?
Ultrasonic scanners of course are better as they benefit from the 3D scanning process, while optical scanners are just capable of 2D scanning as mentioned before.
Besides these, ultrasonic sensors are extremely small in size, Qualcomm’s latest 3D sonic sensor measures just 0.2 mm.
The small form factor of these sensors meets the current demand for slim and bezel-less devices.
Moving further, these sensors are also not affected by dust, grease or wet hands.
However, there are not many devices which make use of ultrasonic sensors and that completely has to do with manufacturing costs.
These sensors are costly and are available only on select devices flagship devices as of now.
What are the recent devices with in-display fingerprint scanners?
Well now that you are aware of the current technologies and their working.
It would be even better if you are aware of the recent devices with in-display fingerprint sensors and their type.
Devices with optical in-display scanners
Devices with ultrasonic in-display scanners
Redmi K20/k20 Pro
Samsung Galaxy S10/S10+
Realme X
One Plus 7/ 7 Pro
OPPO K3
Samsung Galaxy A50/A70/A80
OPPO K1
Vivo V15 Pro
One Plus 6T
Huawei P30 Pro
Xiaomi Mi 9
tutorial/diode-clipper-circuits
Diode Clipper Circuits: Design & Demonstration
As the name suggests, Clipper circuit is used to “clipᾠa portion of input signal without distorting the remaining part of the waveform.
It is a wave shaping circuit.
This can be very useful in the circuits where the input signal attains a higher value of voltage than the expected one.
These circuits can be implemented in various ways according to the configuration or function of the diode.
by using an Oscilloscope.
Series Positive Clipper
Series Positive Clipper with Bias Voltage
Series Negative Clipper
Series Negative Clipper with Bias Voltage
Shunt Positive Clipper
Shunt Positive Clipper with Bias Voltage
Shunt Negative Clipper
Shunt Negative Clipper with Bias Voltage
Combinational Clipper
1. Series Positive Clipper
The diode is connected in series with output as shown in the figure below:
To design the circuit, just follow the circuit diagram above.
First connect the 12V terminal of transformer to diode’s negative end and connect a 10K resistor to diode’s positive end and then connect the 0V terminal of transformer to the other end of resistor.
Now connect the first channel of oscilloscope to input side and the second channel to the output side.
Turn on the transformer and oscilloscope.
And, you’ll see the output signal’s positive half cycle clipped off.
During the positive half cycle the diode is in reverse bias so there is no output voltage, and during the negative half cycle the diode goes in forward bias and the voltage drop occurs across output.
Hence we see the positive half cycle clipped off.
2. Series Positive Clipper with Bias Voltage
(Figure 2), it will clip some part of negative cycle as shown below because the negative voltage will add up with the input voltage.
3. Series Negative Clipper
The diode is connected in series with output as shown in the figure below:
To design the circuit, just follow the circuit diagram above.
Firstly connect the 12V terminal of transformer to diode’s positive end and connect a 10K resistor to diode’s negative end and then connect the 0V terminal of transformer to the other end of resistor.
Now connect the first channel of oscilloscope to input side and the second channel to the output side.
Turn on the transformer and oscilloscope.
And, you’ll see the output signal’s negative half cycle clipped off.
During the positive half cycle the diode is in forward bias so, the voltage drop occurs across output and during the negative half cycle the diode goes in reverse bias and there is no output voltage across output.
Hence we see the negative half cycle clipped off.
4. Series Negative Clipper with Bias Voltage
This works on the same principle as the series positive biased clipper.
But here negative bias voltage is used to clip of the negative portion of the signal because the positive bias voltage will get added to the input voltage.
5. Shunt Positive Clipper
, the diode is connected to the output side and the resistance is connected at input side.
It is called parallel because the output is developed in parallel to the diode.
The circuit diagram is shown below:
.
6. Shunt Positive Clipper with Bias Voltage
This type of clipper also work same as the biased clippers discussed earlier but this time the bias voltage is connected with diode.
So in positive biasing it clips off only the positive part but while it is biased negatively it also clips off some part of negative half cycle as shown in the diagram below.
7. Shunt Negative Clipper
This filter is designed same as the shunt positive clipper, just the diode is connected in reverse.
The circuit diagram is given below:
.
8. Shunt Negative Clipper with Bias Voltage
They are also similar to series negative biased clippers but this time the voltage is connected with diode.
You must use the negative bias voltage to achieve the clipping in negative cycle and positive bias to clip positive cycle.
9. Combinational Clippers
To accomplish this, two diodes are used in opposite directions.
To regulate the clipping a bias voltage can be applied so that the clipping is done to the voltage difference between input and bias voltage.
The circuit diagram is given below:
Just follow the circuit diagram shown above.
This circuit is same as the above parallel/shunt circuits but we’ve used two diodes here.
We’ve made the circuit without using the bias voltage, so in output both the cycles will be clipped off.
During positive half cycle the D2 is forward biased and D1 is in reverse bias.
So D2 will become short circuit and D1 will be open circuit.
And similarly for negative half cycle the opposite of the above condition will occur.
But the output will be at the voltage difference level and as we’ve not used the bias voltage so both the cycles will get clipped off.
interview/kush-cto-of-senra-discusses-how-designers-in-india-can-use-their-lora-gateway-network-in-india
Kush Mishra - CTO of SenRa, discusses how designers can make use of their LoRa Network Gateways in India
seems to get increasingly popular around the globe.
In a typical LoRa system, the LoRa devices (Nodes) have to communicate with a gateway provider to get connected to the internet and form an IoT system.
Given that the technology is still new, gateway providers are still emerging and yet to cover more grounds.
with few questions for which he answers‐
) will you help you in registering and setting up your device with SenRa.
Once you have registered your device you can start communicating with the network and see all the uplink and downlink information on the network portal.
The procedure is straightforward, so users can simply click on the drop down menu and choose their preferred protocol like HTTP, MQTT, AWS or any other platform.
The documentation for all these steps is pretty detailed on our website and our client management team will also be ready to help you if you need any support in this process.
of that network operator.
Comparing SenRa, we are solely focused on LoRa network services and we do not work on any parallel network technology like telephony or telematics.
We also have our own RF Test Lab to focus on the specs and evaluate our gateways for the recommended standards from Lora Alliance and the Department of Telecommunications.
We are also a contributing member of the LoRa Alliance, which means we get to know the technology advancements firsthand.
and we hold ourselves liable to penalties even if the SLA is not met.
We have very strong team working on expanding our networks, so that we can address these coverage issues as fast as possible.
If you are a developer and would just like to test our services you can also use your own gateways and link it with SenRa.
You can refer to our documentation where we have listed all the supported gateways and how to use them.
As a developer you can select the relevant gateway link and follow the steps given.
You will find instructions for most of the popular gateways on our documentation, but you can also select a third party gateway which is not on our list and use it with a sentech packet forwarder to onboard the gateway on SenRa portal.
Since not every smart city is actively taking projects, we discuss with smart city CEOs and PMCs to figure out what kind of timeline we should adapt to address the network needs of a specific smart city.
We are also targeting few countries outside India to take forward our network infrastructure through few other large companies, but that is something we can’t reveal right now.
between network operators.
style.
Ginjer already has a selected statistical report generation feature like histogram adequate support etc, which are readily for allowing you to visualize data.
solution, meaning it is not only limited to LoRa but can also support Sigfox, BLE and other protocols as well.
in the country; you can start using Ginjer platform for a free tier and connect upto 10 devices for free.
After that you will have to pay only about 35Rs per month for one additional device.
We are also in plans to release the Ginjer 2.2 version, probably in the next couple of months which will allow designers to route data from SenRa portal directly into Ginjer and start visualizing data.
In managed parking solution, a parking lot manager can deploy the devices and use our network services and application to regulate parking.
In a illegal parking scenario, the city officials will be provided with a mobile application which can alert them if an illegal parking has occurred somewhere in the city.
The app will also route them to that particular place using open map APIs and they can issue a challan to the illegal parked car.
say like 100% full or 50% full etc.
With this data we can alert the corporation as to which bin needs attention through a mobile app, we also use this analytics data to get the waste bin collectors an optimized route based on the status of the waste bins in that particular locality.
We can also use this data to determine where additional waste bins have to be deployed and which ones should be removed or replaced based the frequency of usage of the waste bins.
where we spend a lot of time to go through complex RF propagation models and we also spend a lot of time in integrating with GIS mapping services or Google APIs to determine the best fit for us.
So I think the government is also contributing strongly in their part of pushing forward the next generation technology like LoRa.
to support us on SenRa.
tutorial/galvanic-isolation-signal-and-power-isolation
Galvanic Isolation ᾠSignal Isolation and Power Isolation
Why the term “Galvanic᾿ It is because galvanic represents the current produced by some sort of chemical action, and since we are isolating this current by breaking conductor contact it is called as Galvanic Isolation.
and choosing the right one depends on the type of isolation, withstanding capacity, application requirements and obviously, the cost factor is also involved.
In this article we will learn about the different types of isolation, how they work and where to use them in our designs.
Types of Galvanic Isolation
Signal Isolation
Power Level Isolation
Capacitors as an Isolator
Signal Isolation
Signal level isolation is required where two circuits of different nature are communicating with each other using some type of signal.
For example, two circuits using independent power source and operating of different voltage levels.
In such cases, to isolate the individual ground of two independent power sources and to communicate between those two circuits, signal level isolation is required.
are majorly used in signal isolation purpose.
Both these isolators protect the different ground sources from combining together.
Each Isolator has its own unique operating principle and application which are discussed below.
, and a phototransistor.
The LED is controlled by the one circuit and the transistor side is connected with the other circuit.
Therefore, the LED and the transistor are not electrically connected.
The communication is only done by lights, optically.
is isolating two independent circuits.
Circuit 1 is the power source with a switch, circuit 2 is a logic level output connected with a different 5V supply.
The logic state is controlled by the left circuit.
When the switch is being closed, the LED inside theoptocouplerlights up and turns on the transistor.
The logic state will be changed from High to Low.
for different application requirements.
are used to isolate the external wiring with internal hardware.
Even telephone lines are used transformer based signal isolators.
But, as transformers are isolated by electromagnetically, it only works with AC.
Above image is the internal schematic ofRJ45jack with integrated pulse transformer for isolatingMCUportion with the Output.
Power Level Isolation
by isolating the high voltage lines from the operator and other parts of the system.
the most commonly usage is to provide low voltage from a high voltage source.
The transformer does not have connections between primary and secondary but could step down the voltage from high voltage AC to low voltage AC without losing the galvanic isolation.
and do not alter the voltage or current level on both sides.
The sole purpose of the isolation transformer is to provide isolation.
available in the electronics market depending on the application.
Popular types are Electromagnetic relays and solid state relays.
An Electromagnetic relay works with Electromagnetic and Mechanically movable parts often referred to as poles.
It contains an electromagnet that moves the pole and completes the circuit.
Relay creates isolation when high voltage circuits need to be controlled from a low voltage circuit or vice-versa.
In such a situation both circuits are isolated but one circuit could energize the relay to control another one.
in terms of working.
Solid state relays work exactly the same but the electro-mechanical part is replaced with an optically controlled diode.
The galvanic isolation can be build up due to the absence of a direct connection between the input and output of the solid state relays.
accurately and help to measure the current flowing through a conductor in a non-invasive way.
It provides proper isolation andensuressafety from hazardous electricity.
Hall Effect sensor uses electromagnetic field generated across the conductor to estimate the current flowing through it.
The core ring is hooked over a conductor in a noninvasive way and it is electrically isolated as shown in the picture above.
Capacitors as an Isolator
Due to inefficiency and dangerous failure outcomes this is no longer preferred, but still knowing it might come in handy when you want to build a crude isolator.
Capacitors block DC and allow passing a high-frequency AC signal.
Due to this excellent property, the capacitor is used as isolators in designs where DC currents of two circuits need to be blocked but still allowing the data transmission.
The above image is showing capacitors are used for isolation purposes.
Transmitter and the receiver both are isolated, but the data communication can be done.
Galvanic isolation ᾠApplications
, galvanic isolation is required for Power Distribution systems, Power generators, measurement systems, Motor controllers, Input-Output logic devices, etc.
also use galvanic isolation.
One common example is Ethernet, Routers, Switchers, Telephone switches, etc.
Normal consumer goods, like chargers,SMPS, computer’s logic boards are the most common products which use galvanic isolation.
Practical Example of Galvanic isolation
overTTLsegment.
One needs to connect a PLC device with an RS-485 port to harvest the data from the transformer.
But the problem is in the direct communication line.
PLC uses very low voltage level and very sensitive with the high ESD or surge.
If a direct connection is employed, the PLC can be at high risk and need to be galvanically isolated.
Those ICs are very useful to protect the PLC from ESD or surges.
As per the datasheet, Both ICs has a withstand capacity of +/-35kVESD and 2.75kVrms withstand isolation voltage up to 60 seconds.
Not only this, but those ICs also confirm445VrmsWorking-isolation Voltage, making it a suitable isolator to be used in industrial automation equipment.
article/how-regenerative-braking-works-in-electric-vehicles
How Regenerative Braking Works in Electric Vehicles
:
An Engineer's Introduction to Electric Vehicles (EVs)Types of Motors used in Electric Vehicles
using Fly wheels.
Flywheels are disks with high inertia which rotate at a very high speed.
They act as a mechanical energy storage device by taking up (storing) the kinetic energy of the vehicle during braking.
The energy recovered during braking process can be used to assist the vehicle during starting or up-hill movement.
Regenerative braking helps in extending the range of the electric vehicle by 8-25%.
Apart from saving energy and enhancing the range, it also helps in effective control of the braking operation.
In the mechanical braking system, a reverse torque is exerted on the wheel when we press the brake pedal.
Similarly, in the regenerative braking mode, the speed of the vehicle is reduced by initiating a negative torque (opposing to the motion) in the motor with the help of the motor controller.
Sometimes people get confused when they visualize the concept that motor acts as a generator when it rotates in reverse direction under regenerative braking mode.
In this article, one can understand how to recover the kinetic energy via regenerative braking method in electric vehicles.
How a Motor acts as Generator
to avoid energy loss due to braking.
When the motor accelerates the vehicle, the kinetic energy associated with it increases as a square of the velocity.
During coasting, the vehicle comes to rest when the kinetic energy becomes zero.
When we apply the brakes in an electric vehicle, the motor controller operates in such a way to bring the motor to rest or to reduce its speed.
This involves in reversing the direction of the motor torque to that of the direction of rotation.
During this process, the rotor of the motor connected to the drive axle generates an EMF in the motor (analogous to a prime mover/turbine driving the rotor of the generator).
When the EMF generated is more than the voltage of the capacitor bank, the power flows from the motor to the bank.
Thus the energy recovered is stored in the battery or the capacitor bank.
How Regenerative Braking works in Electric Vehicle
is the speed of the rotating magnetic field of the stator produced due to the interaction of three phase supply.
At the time of starting the motor, the EMF induced in the rotor is maximum.
As the motor starts rotating the EMF induced decreases as a function of slip.
When the rotor speed reaches the synchronous speed, the EMF induced is zero.
At this point, if we try to rotate the rotor above this speed, EMF will be induced.
In this case, the motor supplies active power back to the mains or supply.
We apply brakes to reduce the speed of the vehicle.
In this case, we cannot expect the rotor speed to exceed the synchronous speed.
This is where the role of motor controller comes into the picture.
For the understanding purpose, we can visualize like the example given below.
Let us assume that the motor is rotating at 5900 rpm and the supply frequency be 200 Hz when we apply brake we have to reduce the rpm or bring it down to zero.
The controller acts according to the input from the brake pedal sensor and carries out that operation.
During this process, the controller will set the supply frequency less than the 200 Hz like 80 Hz.
Therefore the synchronous speed of the motor becomes 2400 rpm.
From the motor controller perspective, the speed of the motor is more than its synchronous speed.
As we are reducing the speed during braking operation, the motor now acts as a generator until the rpm decreases to 2400.
During this period, we can extract power from the motor and store it in the battery or capacitor bank.
It is to note that the battery continues to supply power to the three phase induction motors during the regenerative braking process.
It is because the induction motors do not have a magnetic flux source when the supply is OFF.
Therefore the motor when acts as a generator draw reactive power from the supply to establish the flux linkage and supplies active power back to it.
For different motors, the principle of recovering the kinetic energy during regenerative braking is different.
Permanent magnet motors can act as a generator without any power supply because it has magnets in the rotor to produce magnetic flux.
Similarly few motors have residual magnetism in it which eliminates the external excitation required to create magnetic flux.
In most of the electric vehicles, the electric motor is connected only to the single drive axle (mostly to the rear-wheel drive axle).
In this case, we need to employ a mechanical braking system (hydraulic braking) for the front wheels.
This means that the controller has to maintain coordination between both the mechanical and electronic braking system while applying the brakes.
Is Regenerative Braking worth to be implemented in all Electric Vehicles?
It is because overcharging can damage the batteries, but the electronic circuit prevents from overcharging of it.
In this case, the capacitor bank can store the energy and help in extending the range.
If it is not there, then the mechanical brakes are applied to stop the vehicle.
Though few electric scooters have the feature of regenerative braking, the impact of it on the system (the amount of energy retrieved, or the range extended) is not as effective as in electric cars.
The Need for Capacitor Banks or Ultra Capacitors
can discharge and charge for many cycles without any performance degradation, which helps in increasing the life of the battery.
Ultra capacitor has fast response, which helps in capturing the energy peaks/surge effectively during the regenerative braking operation.
The reason for choosing an ultra capacitor is that it can store 20 times more energy than electrolytic capacitors.
This system houses a DC to DC converter.
During acceleration, the boost operation allows the capacitor to discharge up to a threshold value.
During deceleration (i.e.
braking) the buck operation allows the capacitor to charge.
The ultra capacitors have a good transient response, which is useful during starting of the vehicle.
By storing the recovered energy apart from the battery, it can help in extending the range of the vehicle and can also support sudden acceleration with the help of the boost circuit.
interview/dan-jones-cto-of-chirp-explains-how-they-transmit-data-over-sound-using-ordinary-speaker-and-microphone
Dan Jones, CTO of Chirp explains how they transmit data over sound using ordinary speaker and microphone
has developed an SDK that allows exchange of data over sound by simply using the device speaker and microphone without the need of paring.
On top of that the SDK is platform independent and also supports low power data communication.
, to discuss few questions.
The answers for which is encapsulated below
Chirp is a way to transmit information using sound waves.
In contrast with Wi-Fi or Bluetooth which uses Radio frequencies, Chirp encodes data in tones that can be played (transmitted) using any computer speaker and received through any computer microphone without the need of having any additional hardware like RF chips.
This enables Chirp to be used on any consumer device that has a speaker and microphone in it, like mobile phones, Laptops, PA system etc and can transmit information even through YoutTube stream or TV broadcast.
The encoded audible tones played through the speaker are susceptible to humans and it sounds like a tiny piece of digital bird song, hence the name “chirpᾮ But we can also exploit the fact that computer speaker and microphone can actually also work with ultrasonic frequencies that are inaudible to human ears, this way we can also transmit information over sound that we can’t hear.
One reason will be Chirp’s extremely low friction.
Unlike Bluetooth or Wi-Fi I can use Chirp to immediately initiate one to many communication to share a message with everyone around me without having to pair with them.
It makes it a lot easier to share something quickly and easily to everyone around the room or around the table.
It comes very handy for connecting with people I have not met before or for interacting with machine that I might not have met before.
For example opening a smart locker or sharing a business card etc..
Apart from that, a lot of time we also see Chirp being used in Peer to Peer Communication as well.
For example, Shuttl an Indian bus company is using Chirp between the bus driver and passenger to check if the person has boarded the bus and if his ticket has been redeemed.
Yes, one of the key things to remember about sound it that it is a one too many type of communication, meaning anything nearby that is in the audible range of our transmitter will hear the sound and will receive the data.
This has both advantages and limitations.
The advantage being, it is very easy for multicast sharing.
For things like mesh networking it would possibly work, but you would need a sequence of receivers within the hearing range of one another.
So, normally we tend to use chirp more for one to many broadcast scenarios.
We have a very tiny Demo app called “Chirp Messengerᾠ(available on Android and iOS store) that shows how our SDK works.
To send a message the user can type in the message and press send which will embed the message into an audible tone and play it though my phone speaker.
So, any device nearby, which is running our developer kit, can receive these audio tones through microphone.
These audio tones are decoded to constituent frequency and error correction is applied to counter the effects of noise and distortion to obtain the actual message.
This way Chirp is completely paring free all that is needed is to hear the tones and decode them.
There are some security implications that can be used when sending sensitive data though Chirp, like layering some security features onto the existing protocol.
Since Chirp is just a transfer medium you can embedded anything into those tones.
For example you can use RSA or AES encryption to make your data encrypted before sending it over a chip and then decrypt it using public key cryptography.
We strive to optimize our SDK as much as possible.
We have an amazing embedded DSP team who cut every unnecessary bits and bytes off the code to reduce CPU cycle.
The reason for that is, one of the big area in which we are seeing uptake is with the embedded field chip.
Particularly if you want to communicate with low power and low spec IoT device.
Our SDK can even run on an ARM Cortex M4 processor running at 90Mhzfrequency with less than 100kB RAM.
The power measurements on Cortex-M4 controllers, as measured on our development boards were around 20mA when actively listening and less than 10uA in wake-on-sound mode with 90M cycles per second.
The wake-on-sound mode uses super low power microphones from a manufacturer called Vesper who makes zero power always on microphone.
This way the microphone will be actively listing for sound and when it hears a chrip it will wake the Cortex controller from sleep mode to decode the data.
In terms of range it all depends on how loud the signal is transmitted by the speaker.
Higher the volume of the broadcast the further the range, this is because to receive the information the microphones would have to hear to it first.
We can control the range quite simply by controlling the sound pressure level of the emitting device.
At the far end you can broadcast a chirp to an entire stadium transmitting your data hundreds of meter away or you can lower our speaker volume transmit your data within a room.
In terms of the data rate, the acoustic channel is noisy and hence it is not a rate that could be used to compete with Bluetooth or Wi-Fi.
We are talking about hundreds of bits per second and not in megabits.
Which means Chirp is recommended for being used to send small data like token values etc.
Our fastest protocols run at a 2.5kb/sec, but these are for short range NFC style scenarios.
Over a very long range, data rate would be 10’s of bits per second.
Obviously the environment around us is incredibly noisy, from restaurants to industrial scenarios background noise are always present.
We came originally out of a research University College London, Computer Science Lab which was looking primarily at the problem of how to communicate acoustically in a noisy environment.
And we have multiple PhD’s and Professors trying to crack this problem.
This is where a lot of out researches focus and we have got multiple patents in this area.
As a testament to this, we have operated successfully in a nuclear power plant here in UK.
We were brought on by a company called EDF energy to send ultrasonic payloads over 80 meterrange in the incredibly deafening background environments upto 100 decibels that we have to wear defenders.
Still we were able to attain 100% data integrity over an 18 hour test of the equipment.
We already have a stable SDK for ARM Cortex M4 and M7 and next we are working on send only SDK for ARM Cortex M0 which is a fixed point processor that has no floating point architecture.
We aslso support ESP32 through Arduino platform and have also started to look into FPGA support as well for extremely efficient processes.
Proximity detection is a really good application.
Because only people near you can hear your chirps it can be used as a heuristic to know who is around you.
Chirp is used by a huge social gaming platform called Roblox as a way for the young gamers to detect other people nearby to them, effectively using ultrasonic chirps.
This way I can pull out my mobile and it will acts as an ultrasonic beacon to be discovered by other players in the room to initiate a gaming session.
We are also about to launch a partnership with a major meeting room company to help them with indoor navigation using Chirp.
As you walk from room to room in a building, it is quite important for your device to know which room you are in.
With this organization we are using chirp as a way for your laptop or mobile to tell which room you are currently on and enable you to make a connection to a meeting room.
For smaller business, hobbyists and DIY makers Chirp is completely free up to 10,000 monthly active users.
This is because we really want to see people using our technology and the developer community experimenting with it.
Apart from that we also want to support small business.
For larger enterprises and customers we tend to charge them an annual fee
article/debunking-the-magic-behind-sensors-used-in-self-driving-cars
Debunking the Magic behind Sensors used in Self Driving Vehicles
On a fine morning you are crossing the road to reach your office on the other side, just when you are half the way through you notice a driverless piece of metal, a robot, advancing towards and you get into a dilemma deciding on to cross the road or not? A strong question presses your mind, “Did the car notice me?ᾠThen you feel relieved when you observe that the speed of vehicle is being automatically slowed down and it makes a way out for you.
But hold on what just happened? How did a machine get human level intelligence?
, their driving standards, the major key players, their current development and deployment stage etc.
For all this we will be considering self-driving cars because they make a major market share of the autonomous vehicles.
History of Self-Driving Cars
driven by Elon Musk also banged the market to make things spicy.
but complete human control of the vehicle.
A low-level assistance of the car such as acceleration control or the steering control but not both simultaneously.
Here the major tasks such as steering, breaking, knowing the surrounding are still controlled by the driver.
At this level car can assist both the steering and acceleration while most of the critical features are still monitored by the driver.
This is the most common level we can find in cars that are on the road nowadays.
Moving on to level 3 where the car monitors the environmental conditions using sensors and take necessary actions such as braking and rolling on the steering, whereas the human driver is there to intervene the system if any unexpected condition arises.
This is a high level of automation in which the car is capable of completing the entire journey without the human input.
However, this case comes with its own condition that the driver can switch the car into this mode only when the system detects that the traffic conditions are safe and there is no traffic jam.
This level is for the fully automated cars that don’t exist till date.
Engineers are trying to make it happen.
This will enable us to reach our destination without a manual control input to steering or brakes.
Various types of Sensors used in Autonomous/Self-Driving Vehicles
are shown below.
, but we can’t ignore the contribution of other sensors such as Ultrasonic sensor, temperature sensors, Lane detection sensors and GPS as well.
, sonar, radar & cameras for object & obstacle detection, classification & tracking) using basic sensors used in every self-driving vehicle.
The above graph shows the patent filing trends for self-driving vehicles keeping focus on the usage of sensors in it, as it could be interpreted that the development of these vehicles with the help of sensors started around 1970s.
Though the development pace was not fast enough, but increasing at a very slow pace.
The reasons of this could be numerous like undeveloped factories, undeveloped proper research facilities and laboratories, unavailability of high end computing and of course unavailability of the high speed internet, cloud and edge architectures for the computation and decision making of self-driving vehicles.
Because, during this period there was only a single company responsible for it I.e.
General motors and in the next years this race was joined by tech giant Google and now various companies are working on this technology.
In the coming years it can be forecasted that a whole new set of companies will be coming into this technology area taking the research further in different ways.
RADARs in Self-Driving Vehicles
earlier.
The Radar technology first found its wide spread use during the World War II, with application of German inventor Christian Huelsmeyer patent 'telemobiloscopeᾠan early implementation of radar technology that could detect ships up to 3000 m away.
Fast forwarded today, the development of the radar technology has brought many use cases across the world in the military, airplanes, ships and submarines.
anging, and pretty much from its name it can be understood that it works on radio waves.
A transmitter transmits the radio signals in all directions and if there’s an object or obstacle in the way, these radio waves reflect back to the radar receiver, the difference in transmitter and receiver frequency is proportional to the travel time and can be used to measure the distances and distinguish between different types of objects.
from the sensor.
Unlike the vision systems such as camera’s it can see at night or in bad weather and can predict the distance and speed of object from hundreds of yards.
The downside with RADAR is that, even the highly advanced radars can’t predict their environment clearly.
Consider that you are a cyclist standing in front of a car, here Radar can’t predict surely that you are a cyclist but it can identify you as an object or an obstacle and can take necessary actions also it can’t predict the direction in which you are facing it can only detect your speed and moving direction.
since they are detail specific but their range is of few hundred meters only.
This is a sole exception to the autonomous car maker TESLA as they use RADAR as their prime sensor and Musk is confident that they will never need a LiDAR in their systems.
are listed below
By adding the inputs from the GPS and RADAR, Bosch’s system can take real time data and compare it to the base map, match the patterns between the two, and determine its locations with high accuracy.
With the help of this technology car can drive themselves in a bad weather conditions without relying much upon cameras and LiDAR’s.
WaveSense is a Boston based RADAR company which believes that self-driving cars do not need to perceive their surrounding as same as humans.
and gets the signal back which maps the soil type, density, rocks, and infrastructure.
The map is a unique finger print of the road.
Cars can compare their position to a preloaded map and localize themselves within 2 centimeters horizontally and 15 centimeters vertically.
The wavesense technology is also not dependent upon weather conditions.
Ground penetrating radar is traditionally being used in the archaeology, pipe line work and rescues; wavesense is the first company to use it for the automotive purposes.
, but till now the problem was that they were tough to manufacture in a small size for automotive use.
, they could be easily designed.
Lunewave is designing 360 degree antennas with the help of 3D printing roughly to the size of a ping-pong ball.
The unique design of antennas allows the RADAR to sense obstacle at a distance of 380 yards which is nearly double that could be achieved by a normal antenna.
Further, the sphere permits the sensing capability of 360 degrees from a single unit, rather than 20-degree traditional view.
Due to small size it is easier to integrate it in the system, and reduction in the RADAR units decreases the multi-image stitching load over the processor.
LiDars in Self-Driving Vehicles
with the help of a point cloud.
However, it can’t match the resolution of the camera but still it is clear enough to tell the direction in which an object is facing.
in this article.
Although LiDAR seems to be an implacable imaging technology, it has its own drawbacks like
High operative cost and tough maintenance
Ineffective during heavy rain
Poor imaging at places having high sun angle’s or huge reflections
for the imaging the environment.
and its covering range is shown below.
.ᾠAlso universities are backing up musk’s decision of dumping LiDAR’s since two inexpensive cameras on either side of a vehicle can detect objects with nearly LiDAR’s accuracy with just fraction of the cost of LiDAR.
The cameras placed on either side of a Tesla car is shown in below image.
Cameras in Self-Driving Vehicles
related articles that we have covered earlier.
Cameras in vehicles are being used for much a long time with an application such as in parking assistance and monitoring the rear of cars.
Now as the technology of self-driving vehicle is developing the role of camera in vehicles are being re-thought.
While providing a 360-degree surrounding view of the environment, cameras are able to drive the vehicles autonomously through the road.
are used and at the rear end a parking camera is used.
All these camera units bring the images to the control units and it stitches the images to have a surround view.
Other type of sensors in Self-Driving Vehicles
etc.
The future of self-driving vehicles is exciting and is still under development, in future many companies would be coming forward to run the race, and with this many new laws and standards would be created to have a safe use of this technology.
interview/wireless-vidyuth-developing-wireless-chargers-for-electric-vehicles-in-india
Wireless Vidyuth - Developing wireless chargers for Electric Vehicles in India
Indian Government along with the automobile sectors is trying hard to achieve their realistic goals of having 30% Electric vehicles on road by the year 2030.
Despite the subsidies and regulations made by the government this doesn’t seem to work so far because EV’s on Indian roads have not received much appreciation from public in general.
Looking for the reason, everything boils down to two things, which is the poor range and longer charging time associated with electric vehicles.
Unlike IC vehicles the rides on EVs have to be planned because you can’t charge your vehicle on the run…‐t! Wait a minute.
What if I said it is possible to charge your EV even while you are driving it? No I am not talking about the solar or regenerative system here.
I am talking about a real charger that can be buried under the roads to charge your EV wirelessly as you drive on it.
Excited right?
This is exactly what “Wireless Vidyuthᾬ a start-up from Bangalore is currently working on.
The company, co-founded by Tetiana Skupova (Tania) and Nagendra R Gouthamas is currently working on static wireless chargers and is soon to move into dynamic wireless chargers for EV.
Excited by its plan, CircuitDigest approached the duo with few questions and their answers are as follows.
Being interested in Renewable Energy I was looking for something exciting to work on, something that could change our life for the better.This was when I met Nagendra, our chief power electronics engineer at Wireless Vidyuth.
He actually reached me through LinkedIn after watching one of videos on Insky Energy project, at which as well I am the co-founder.
When I heard how he explains his ideas I noticed how passionate and dedicated he is to work on this and get it done.
But he didn’t have a broader picture on how to develop the idea and make business out of it.
So, I started to learn more about the project and Nagendra introduced me technical aspects and documents.
That is how our journey started for Wireless Vidyuth.
Today we have put together a dedicated team of 10 people at our Bangalore office, which are currently working on our second prototype model.
Right now we have completed our first prototype model and are working on the second one.
We are also planning to test it practically at few places in India about which Nagendra will speak on later.
I believe that we will increase trustworthiness to our technology when we will be able to demonstrate its efficiency with our second prototype.
On that stage we will be able to persuade stakeholders that our technology outperforms our competitors in terms of price and efficiency.
So we are intended to involve stakeholders and invite investors to fund our project after finishing and testing the second prototype.
The idea of wireless power flashed from the great scientist and inventor, Nikola Tesla.
He is like the father of all Wireless Technologies in today’s world.
After completing my engineering, I started searching for the companies who were working on wireless power technologies, which is my passion from engineering days.
But then I came to know that there is no company in India which is working on wireless power, so I started searching for potential partners who can take my idea to the next level.
This is how I met Tania.
Initially, I had bigger plans for building back a Wardenclyffe tower (The Tesla Tower) and wireless power system of electricity generation.
Together we chose the approach “Think Big, Start Smallᾮ So we decided to begin with a smaller idea and build a high frequency wireless power transmission system by resonant inductive coupling for static charging of electric vehicles.
This system can be used for static wireless charging of Electric Vehicles.
Once this is achieved we will also be moving into implementation of Dynamic charging.
and the other is Microwave power transmission.
Under inductive coupling we will have static chargers and dynamic charging systems.
The static charger will transfer power when the vehicle is stationary, for instance, at a parking lot or garage.
The transmitter on the charger will turn on only when the vehicle is detected and transmitting AC power will be picked by the receiver coil on the EV.
The other method of inductive charging is the dynamic charging, with which we will be able to charge the vehicle even when it on the run by setting up a wireless charging corridor.
As of now we have already built a small working prototype model which is version one.
It can be used for a lesser power transmission capacity using the method of high frequency resonant inductive coupling.
Now we are building our second prototype wireless charger with a higher power rating in the range of Kilo Watts that is around 2KW.
It can work on normal household supply voltage of 230V with an efficiency of 90% to 95%, meaning the Q-factor of both the transmitter and receiver coil will be higher.
It will just act like a transformer but without any core inside it.
We approached the local electricity supply company BESCOM (Bangalore Electricity Supply Company) for supporting us with building a prototype for static charging.
They expressed their interest in installing wireless charging units for both static and dynamic charging after testing our second prototype.
We plan to set up our first wireless chargers at BESCOM’s office.
Recently the global scenario for EV changed a lot and there is a tremendous interest in creating EV ecosystem.
Many developed countries implemented regulation aiming to switch completely to electric vehicles.
India is also pushing hard on it.
So, it is clear that the world is looking for a new solutions how to switch to EV faster and wireless charging is one of the technological innovations to address this issue.
The EV sector skyrocketed with billions of dollars investments, but current EV manufacturers still working hard to find efficient solutions to pain problems like range and charging time.
Wireless charging might be the one.
With dynamic chargers EVs can get charged on the run.
It will also reduce the battery size of the EV by two thirds, making it much lighter.
Wireless electricity transfer works on the principle of “mutual inductanceᾠbetween two coils.
The transmitter coil is connected to the AC supply and the receiver coil is connected to the load.
The load in our case will be the battery through the on-board charger.
When the power is switched on to the transmitter, coil converts electricity into magnetic field, which is oscillating at a resonant frequency.
Then the receiver coil at the receiving end converts this magnetic into electricity.
The power can be transferred from transmitter coil to receiver coil based on faraday’s laws of electromagnetic induction.
The current entering at one end and leaving at another end of coil is determined by dot convention.
The core technology used in the wireless power transmission system is high frequency Inductive coupling through magnetic fields.
An Impedance compensating circuit is also used to achieve maximum power transfer.
In another six to seven months, after we are done our static charger prototype (model 2), we plan to install them at the parking lot of BESCOM corporate office in Bangalore.
For the second run, we plan to develop dynamic charging by setting up a wireless charging corridor using segment control technology.
It can be implemented at Vidhana Soudha in Bangalore, making it iconic place by having India’s first wireless charging corridor.
In these wireless corridors, the transmitter side of the charger will be buried in series under the ground.
These transmitter pads will be energized only when the receiving pad comes on top of that particular transmitter.
This improves power efficiency and gives a sense of safety, because when other IC powered vehicles or pedestrians walk on the road these transmitters will remain turned off.
Every EV will come with its own specification of battery pack, which will be charged by its on-board charger.
For the wireless chargers the transmitter part will remain the same for all vehicles, but some modifications has to be made on the receiver side based on the type of on-board charger in that particular EV.
Once these receiver coils are fitted to an EV, it can make use of any wireless charger (transmitter) installed in the city.
Our transmitting and receiving pad can be added as an accessory to the existing EVs.
The wireless chargers work with the same principle as that of transformer.
A transformer normally has an efficiency of 98 to 99%.
But wireless chargers do have some charging losses and we are trying to achieve a charging efficiency of 95%.
We are sure that our charger efficiency will not be below 90%.
We are working on making wireless charging affordable and competitive.
We consider that the cost is not final and it will decrease with time.
As we know, a lot of technologies were much more costly at the time they were just launched than we have it today.
After adoption and technological improvement the price gets reduced.
One example is costs for communication.
Another one is solar panels‐en they were introduced over 50 years ago it seemed to be very expensive.
But now their price has become 200+ times less expensive than what it was at the beginning.
Of course, our goal would be to make the technology affordable.
So once we got the initial things set up we will work on making it cheaper.
And for the dynamic chargers we are planning to work on different business models during the later stages of our project, so that we can tackle this problem of cost.
Since Wireless Vidyuth is the only player in India, who is working on Wireless Power transfer for Electric vehicles, we do face some difficulties in getting things moving initially.
Most components required for our project, like the high speed switching MOSFETS, were not available in India and finding a vendor for it was a problem.
We had to import it from outside for out project.
Another technological hurdle in the wireless charger is to actually get the receiver coil in the EV to be aligned with the transmitter coil of the charger for maximum power transfer and we are currently working on improving it.
article/wireless-electric-vehicle-charging-systems
Wireless Electric Vehicle Charging System (WEVCS)
, traveling range and charging process are the two major issues affecting it’s adoption over conventional vehicles.
With the introduction of Wire charging technology, no more waiting at charging stations for hours, now get your vehicle charged by just parking it on parking spot or by parking at your garage or even while driving you can charge your electric vehicle.
As of now, we are very much familiar with wireless transmission of data, audio and video signals so why can’t we transfer power over the Air.
1917
Static and Dynamic Wireless Charging
,
Static Wireless Charging
Dynamic Wireless Charging
As the name indicates, the vehicle gets charged when it remains static.
So here we could simply park the EV at the parking spot or in garage which is incorporated with WCS.
Transmitter is fitted underneath the ground and receiver is arranged in vehicle’s underneath.
To charge the vehicle align the transmitter and receiver and leave it for charging.
The charging time depends on the AC supply power level, distance between the transmitter & receiver and their pad sizes.
This SWCS is best to build in areas where EV is being parked for a certain time interval.
As the name indicates here vehicle get charged while in motion.
The power transfers over the air from a stationary transmitter to the receiver coil in a moving vehicle.
By using DWCS EV's travelling range could be improved with the continuous charging of its battery while driving on roadways and highways.
It reduces the need for large energy storage which further reduce the weight of the vehicle.
Types of EVWCS
Based on operating Techniques EVWCS can be classified into four types
Capacitive Wireless Charging System (CWCS)
Permanent Magnetic Gear Wireless Charging System (PMWC)
Inductive Wireless Charging System (IWC)
Resonant Inductive Wireless Charging System (RIWC)
correction circuit to improve efficiency and to maintain the voltage levels and to reduce the losses while transmitting the power.
Then it is supplied to an H-bridge for the High-frequency AC voltage generation and this high frequency AC is applied to transmitting plate which causes the development of oscillating electric field that causes displacement current at receiver plate by means of electro static induction.
The AC Voltage at receiver side is converted to DC to feed the battery through BMS by rectifier and filter circuits.
Frequency, voltage, size of coupling capacitors and air-gap between transmitter and receiver affects the amount of power transferred.
It’s operating frequency is between 100 to 600 KHz.
The generated AC power at receiver side fed to the battery after rectifying and filtering through power converters.
Here wireless transmission of power is achieved by mutual induction of magnetic field between transmitter and receiver coil.
When the main AC supply applied to the transmitter coil, it creates AC magnetic field that passes through receiver coil and this magnetic field moves electrons in receiver coil causes AC power output.
This AC output is rectified and filtered to Charge the EV’s energy storage system.
The amount of power transferred depends on frequency, mutual inductance and distance between transmitter and receiver coil.
Operating frequency of IWC is between 19 to 50 KHz.
Basically resonators having high Quality factor transmit energy at much higher rate, so by operating at resonance, even with weaker magnetic fields we can transmit the same amount of power as in IWC.
The power can be transferred to long distances without wires.
Max transfer of power over the air happens when the transmitter and receiver coils are tuned i.e., both coils resonant frequencies should be matched.
So to get good resonant frequencies, additional compensation networks in the series and parallel combinations are added to the transmitter and receiver coils.
This additional compensation networks along with improvement in resonant frequency also reduces the additional losses.
Operating frequency of RIWC is between 10 to 150 KHz.
Wireless Electric Vehicle Charging Standards
Wireless charging makes EV to charge without any need of plug in.
If every company makes its own standards for wireless charging systems that won’t compatible with other systems then it won’t be a good thing.
So to make wireless EV charging more user friendly Many international organizations like International Electro Technical Commission (IEC), the Society of Automotive Engineers
(SAE), Underwriters Laboratories (UL) Institute of Electrical and Electronics Engineers (IEEE) are working on standards.
SAE J2954 defines WPT for Light-Duty Plug-In EVs and Alignment Methodology.
According to this standard, level 1 offers maximum input power of 3.7 Kw, level2 offers 7.7Kw, level 3 offers 11Kw and level4 offers 22Kw.
And the minimum target efficiency must be greater than 85% when aligned.
Allowable ground clearance should be up to 10 inches and side to side tolerance is upto 4 inches.
The most preferable alignment method is magnetic triangulation that assists to stay within charge range in manual parking and assists to find parking spots for autonomous vehicles.
SAE J1772 standard defines EV/PHEV Conductive Charge Coupler.
SAE J2847/6 standard defines Communication Between Wireless Charged Vehicles and Wireless EV Chargers.
SAE J1773 standard defines EV Inductively Coupled Charging.
SAE J2836/6 standard defines Use Cases for Wireless Charging Communication for PEV.
UL subject 2750 defines Outline of Investigation, for WEVCS.
IEC 61980-1 Cor.1 Ed.1.0 defines EV WPT Systems General Requirements.
IEC 62827-2 Ed.1.0 defines WPT-Management: Multiple Device Control Management.
IEC 63028 Ed.1.0 defines WPT-Air Fuel Alliance Resonant Baseline System Specification.
Companies Currently Developed and Working on WCS
Evatran group's making Plugless Charging for passenger EVs like Tesla Model S, BMW i3, Nissan Leaf, Gen 1 Chevrolet Volt.
WiTricy Corporation is making WCS for Passenger cars and SUVs till now it is working with Honda Motor Co.
Ltd, Nissan, GM, Hyundai, Furukawa Electric.
Qualcomm Halo is making WCS for Passenger, sport and race car and it is acquired by Witricity corporation.
Hevo Power is making WCS for Passenger car
Bombardier Primove is making WCS for Passenger car to SUVs.
Siemens and BMW is making WCS for Passenger car.
Momentum Dynamic is making WCS Corporation Commercial fleet and Bus.
Conductix-Wampfler is making WCS for Industry fleet and Bus.
Challenges Faced by WEVCS
To install static and dynamic wireless charging stations on the roads, new infrastructure development is required as current arrangement are not suitable for the installations.
Need to maintain the EMC, EMI and frequencies as per standards for the human Health and safety concern.
tutorial/maxwells-equations-explained
Understanding Maxwell Equations
relating the electric and magnetic fields.
Instead of listing out the mathematical representation of Maxwell equations, we will focus on what is the actual significance of those equations in this article.
The Maxwell’s First and Second equation deals with static electric fields and static magnetic fields respectively.
The Maxwell’s Third and Fourth equation deals with changing magnetic fields and changing electric fields respectively.
Gauss Law Of Electricity
Gauss Law of Magnetism
Faraday’s Law of Induction
Ampere’s Law
1. Gauss Law Of Electricity
This law states that the Electric Flux out of a closed surface is proportional to the total charge enclosed by that surface.
The Gauss law deals with the static electric field.
Let us consider a positive point charge Q.
We know that the electric flux lines are directed outwards from the positive charge.
in it.
The Area Vector is always chosen Normal to it because it represents the orientation of the surface.
Let the angle made by the Electric field vector with the area vector be θ.
The reason for choosing the dot product is that we need to calculate how much electric flux passes through the surface represented by a normal area vector.
is:
The region enclosing the charge can be of any shape but to apply Gauss law, we have to select a Gaussian surface which is symmetric and has uniform charge distribution.
The Gaussian surface can be cylindrical or spherical or a plane.
To derive its Differential form, we need to apply Divergence theorem.
represents the Volume charge density.
When we have to apply the Gauss law to a surface with a line charge or surface charge distribution, it is more convenient to represent the equation with charge density.
By applying divergence to a vector field, we can know whether the surface enclosed by the vector field is acting as a source or sink.
with a positive charge as shown above.
When we apply divergence to the electric field coming out the box (cuboid), the result of the mathematical expression tells us that the box (cuboid) considered acts as a source for the electric field computed.
If the result is negative, it tells us that the box acts as a sink i.e.
the box encloses a negative charge in it.
If the divergence is Zero, it means that there is no charge in it.
2. Gauss Law of Magnetism
We know that the magnetic flux line flows from North pole to south pole externally.
Even when we apply divergence of the magnetic field (B) due to a current carrying wire, it turns out to be zero.
The integral form of Gauss law of Magnetism is:
The differential form of Gauss law of Magnetism is:
From this, we could infer that magnetic monopoles do not exist.
3. Faraday’s Law of Induction
Faraday’s law states that when there is a change in magnetic flux (changing with respect to time) linking a coil or any conductor, there will be an EMF induced in the coil.
Lenz’s stated that the EMF induced will be in a direction such that it opposes the change in magnetic flux producing it.
In the above illustration, when a conducting plate or a conductor is brought under the influence of a changing magnetic field, circulating current is induced in it.
The current is induced in such a direction that the magnetic field produced by it opposes the changing magnetic that created it.
From this illustration, it is clear that changing or varying magnetic field creates a circulating electric field.
From Faraday’s law,
emf = - d / dt
We know that,
= closed surface B .
dS
emf = - (d/dt) B .
dS
Electric Field E= V/d
V= E .dl
Since the electric field is changing with respect to the surface (curl), there exists a potential difference V.
Therefore the integral form of Maxwell’s fourth equation is,
By applying Stoke’s theorem,
The reason for applying Stoke’s theorem is that when we take a curl of a rotating field over a closed surface, the internal curl components of the vector cancels each other and this results in evaluating the vector field along the closed path.
Hence we can write that,
The differential form of Maxwell’s equation is
From the above expression, it is clear that a magnetic field changing with respect to time produces a circulating Electric field.
In electrostatics, the curl of an Electric field is zero because it emerges radially outwards from the charge and there is no rotating component associated with it.
4. Ampere’s Law
Ampere’s law states that when an electric current flows through a wire, it produces a magnetic field around it.
Mathematically, the line integral of the magnetic field around a closed loop gives the total current enclosed by it.
B .dl = μ0 Ienclosed
Since the magnetic field curls around the wire, we can apply Stoke’s theorem to Ampere’s law.
Therefore the equation becomes
We can represent the current enclosed in terms of current density J.
by using this relation, we can write the expression as
When we apply divergence to the curl of a rotating vector field, the result is zero.
It is because the closed surface doesn’t act as a source or sink i.e.
the number of flux coming in and going out of the surface is the same.
This can be mathematically represented as,
Let us consider a circuit as illustrated below.
The circuit has a capacitor connected to it.
When we apply divergence in the region S1, the result shows that it is non-zero.
In mathematical notation,
) considering the symmetry of the Faraday’s law i.e if a magnetic field changing in time produces an Electric field then by symmetry, changing electric field produces a magnetic field.
The curl of magnetic field intensity (H) in the region S1 is
The integral form of Maxwell’s fourth equation can be expressed as:
The differential form of Maxwell’s fourth equation is:
tutorial/transimpedance-amplifier-design-working-and-applications
Transimpedance Amplifier - Current to Voltage Converter
, so in this article we will learn more about it and how to use it in your circuit designs.
Importance of Transimpedance Amplifier
Now that we know even a resistor can be used to convert current to voltage, why do we have to build an active current to voltage converters using Op-Amp? What advantage and importance does it have over Passive V to I converters?
To answer that lets assume a photosensitive diode (current source) is providing current across its terminal depending on the light falling on it and a simple low-value resistor is connected across the photodiode to convert the output current to a proportional voltage as shown in the image below.
and the flexibility of the output voltage is limited.
Therefore, to fix the poor gain and noise related issues, a Transimpedance amplifier is often preferred.
Adding to this in a Transimpedance amplifier, the designer can also configure the bandwidth and the gain response of the circuit as per the design requirements.
Working of Transimpedance Amplifier
Along with the amplifier, a single feedback resistor (R1) is connected to the inverting end of the Amplifier as shown below.
due to its high input impedance, hence the current from our current source has to completely pass through resistor R1.
Let’s consider this current as Is.
At this point, the output voltage (Vout) of the Op-Amp can be calculated using the below formula -
Vout = -Is x R1
are connected in parallel between the amplifiers negative input and the output as shown below.
The operational amplifier here is again connected in negative feedback condition through the resistor R1 and the capacitor C1 as the feedback.
The current (Is) applied to the Inverting pin of the Transimpedance amplifier will be converted into equivalent voltage on the output side as Vout.
The value of the input current and the value of resistor (R1) can be used to determine the output voltage of the Transimpedance amplifier.
is shown below.
C1 ≤ 1 / 2π x R1 x fp
is the required bandwidth frequency.
behavior.
Transimpedance Amplifier Design
using Op-amp is shown below
as discussed earlier.
For the perfect operation, the op-amp also gets power from a dual power rail supply which is +/- 12V.
The feedback resistor value is selected as 1k.
Transimpedance amplifier Simulation
The above circuit can be simulated to check if the design works as expected.
A DC voltmeter is connected across the op-amp output to measure the output voltage of our Transimpedance amplifier.
If the circuit is working properly, then the value of output voltage displayed on the voltmeter should be proportional to the current applied to the inverting pin of the Op-Amp.
can be found below
, the current start to flow through the feedback resistor and the output voltage is dependable on the feedback resistor value times the current is flowing, governed by the formula Vout = -Is x R1 as we discussed earlier.
In our circuit the value of Resistor R1 is 1k.
Therefore, when the input current is 1mA, the Vout will be,
Vout = -Is x R1
Vout = -0.001 Amp x 1000 Ohms [1mA and the 1 Kilo-Ohms]
Vout = 1 Volt
result, it matches exactly.
The output became positive by the effect of Transimpedance amplifier.
, the input current across the op-amp is given as .05mA or 500 microamperes.
Therefore the value of output voltage can be calculated as.
Vout = -Is x R1
Vout = -0.0005 Amp x 1000 Ohms [1mA and the 1 Kilo-Ohms]
Vout = .5 Volt
If we check the simulation result, this also matches exactly.
Once again this is a simulation result.
While building the circuit practically simple stray capacitance could produce time constant effect in this circuit.
The designer should be careful about the below points when constructing physically.
Avoid breadboards or copper clad boards or any other strip boards for connection.
Build the circuit only on PCB.
The Op-Amp need to be soldered directly to the PCB without IC holder.
Use short traces for feedback paths and the input current source (Photodiode or similar things that are needed to be measured by a Transimpedance amplifier).
Place the feedback resistor and the capacitor as close as possible to the operational amplifier.
It is good to use short leaded resistors.
Add proper filter capacitors with both large and small values on the power supply rail.
Choose proper op-amp specially designed for this purpose of the amplifier for simplicity of the design.
Applications of Transimpedance Amplifier
for light sensing related operation.
It is widely used in chemical engineering, pressure transducers, different types of accelerometers, advanced driver assistance systems and LiDAR technology which is used in autonomous vehicles.
The most critical part of the Transimpedance circuit is design stability.
This is because of the parasitic and the noise related issues.
The designer must be careful about choosing the right amplifier and should be careful to use proper PCB guidelines.
article/new-metering-technology-makes-every-drop-count
New metering technology makes every drop count
The statistics are alarming: In the United States alone, household leaks waste about 900 billion gallons of water each year.
To put that number in perspective, that’s enough water to supply about 11 million homes annually.And other countries ᾠfrom Europe to Asia ᾠface similar challenges.
Compounding this problem are anticipated water shortages.
But help is here.
Ultrasonic technology gives water meters installed in smart buildings and smart cities the ability to detect and localize leaks as small as one drop every few seconds.
Cities from Austin to Antwerp are installing high-tech smart water meters that give customers the information they need to find leaks and conserve water while helping utilities identify infrastructure leaks in aging pipes and broken water mains.
“The water we have today is the only water we will ever have,ᾠsays Holly Holt-Torres, water conservation manager for the City of Dallas Water Utilities.
“We have to conserve it.
Technology will allow us to do that at an increasingly higher level.ᾍ
But this ultrasonic technology has applications that extend beyond water meters.
The same technology can be used in meters that measure natural gas flow and even detect the mixture of gas flowing through pipes.
It can even help medical professionals regulate oxygen delivery in surgical equipment.
Going with the flow
Ultrasonic waves, of course, are not new.
Bats, for example, use ultrasonic ranging to avoid obstacles and catch insects at night.
And in more high-tech applications, it is used in material discernment, collision avoidance in automobiles, and industrial and medical imaging.
Now it’s being used in water meters and other flow meters.
Meters traditionally have relied on an electromechanical system with a turning spindle or gear that uses a magnetic element to generate pulses.
But ᾠas is the case with thermostats, motors and lots of other everyday devices ᾠelectromechanical systems in flow meters are rapidly transitioning to electronic systems.
In these systems, a pair of immersive ultrasonic transducers measures the velocity of acoustic waves in the fluid.
The velocity of acoustic wave propagation is a function of the viscosity, flow rate and direction of the fluid flowing through the pipe.
Ultrasonic waves travel at different speeds depending on the stiffness of the media they’re traveling through.
The accuracy of the measurement depends on the quality of the transducer, precision analog circuitry and signal processing algorithms.
Acoustic or ultrasonic transducers are piezo materials that convert electric signals to mechanical vibrations at a relatively high frequency of hundreds of kilohertz.
Typically, a pair of ultrasonic transducers in the range of 1-2 MHz must be well-matched and calibrated in order to measure flow accurately.
They make up a significant part of the flow meter’s cost.
The sensor system must operate at very low power to ensure a 15-20 year battery life.
, includes a unique analog front end and algorithm, which significantly improves accuracy while reducing overall cost and power consumption.
Our flow metering architecture leverages high-performance analog design, advanced algorithms and embedded processing to mitigate the need for an expensive pair of ultrasonic transducers.
Analog front end and signal processing algorithms compensate for transducer mismatch.
Making every drop count
A typical ultrasonic flow meter transmits an ultrasonic wave and measures the differential delay at the receiver to estimate the rate of the flow.
Delay measurements are usually handled by a time-to-digital-converter circuit that monitors the zero crossing of the received waveform.
The challenge with the typical approach is that it is not sensitive enough to detect flow levels with high accuracy.
Our architecture deploys a smart analog front end featuring a high-performance analog-to-digital converter to improve signal-to-noise quality and overcome calibration inaccuracies.
This approach has several benefits:
It can achieve higher accuracy by reducing interference and improving signal-to-noise ratio.
The architecture can measure a wide dynamic range of flow, from a fire hose to a small leak.
By using a lower voltage driver, it significantly saves on power and cost.
The average current for one measurement per second is less than 3 microamps.
This translates to a battery life of more than 15 years.
It can detect turbulence, bubbles and other flow anomalies, which is important for flow analysis and servicing the pipelines.
The technology is robust to amplitude variations in the two directions of the flow, which may occur in water and gas at higher flow rates.
Many other TI technologies are critical for a high-performance flow meter.
A low-power microcontroller with integrated ultrasonic analog front end, a high-performance clock reference, a low-quiescent current power management and ultra-accurate impedance matching of transmit driver and receive amplifier paths are examples of additional differentiating technologies in these flow meters.
Together, these technologies can help conserve one of our most precious resources.
tutorial/what-is-dcr-in-inductors-and-how-does-it-affects-your-circuit-design
What is DCR in Inductors and how does it affect your circuit design
of an inductor during its construction.
to know more about it and their importance in circuit design.
What is DCR in Inductors?
In practice all inductors will have a small value of DCR associated with it.
The below image represents a practical Inductor with its actual inductance in series with a small DC resistance (DCR).
The inductor symbol here is representing the inductance and the resistor in series with it is the DC resistance of the Inductor.
In principle Inductors provide a very low resistance for DC current with low frequency and provides high resistance for high frequency inputs.
using which the inductor is made.
The resistance of the coil is proportional to the length of the wire used to form the coil, and the length of coil is also proportional to the inductance value of the Inductor.
Hence, higher value inductors impose high resistance and low-value inductors provide low resistance.
A large value of inductance requires higher winding numbers than the low-value inductors, thus increasing the copper wire length.
The DCR of the Inductors typically ranges from far less than the 1 Ohms to 3-4 Ohms.
Practical Importance of DCR
Now we know that inductors have a small value of resistance with it, but what is the problem with that? Why is it important to consider this small value of resistance while designing our circuit?
just like any other resistor with a voltage drop across it.
The efficiency is measured using the below formula
Q = w (L/R)
L is the inductive reactor and R is the resistance of the Inductor at a particular frequency.
The ratio of an inductive reactance with the resistance at a given frequency is called the Q-factor.
This Q factor is essential in various applications.
Higher the Q factor is, higher will be the efficiency.
If theoretically calculated, an ideal inductor has a higher Q factor compared with the real one.
In real Inductors, this Q factor is dependable in DCR.
In such a case, the high value of the Q factor of an inductor helps to balance the upper and lower frequency of the resonant circuit operating in a continuous band frequency.
R where the R is equivalent of Inductors DC resistance and I is the current flowing through it.
How to measure DCR of an Inductor?
Most people measure the DC Resistance (DCR) of an Inductor by connecting a standard multi-meter across the Inductor leads to measure the resistance of the copper wire.
It might work fair enough for large value inductors, because the copper wire there is large enough to produce a high DCR value that can be measured by the typical multi-meter resolution.
But, for a smaller value inductor the DC resistance value is too small (typically in mili-ohms range) to be measured by the standard low-cost multi-meters.
Also Multi-meter’s probe wires also have DC resistance which adds up to DCR value resulting in faulty reading.
So, there is a generic problem in Inductor’s DCR measurement.
This voltage can be measured using the multi-meter.
Obviously, this measurement technique has a limitation.
Before taking the measurement one should need to be aware about a few things which are listed below.
The maximum current rating of the Inductors.
Current should not be exceeding the maximum current rating stated in the Inductor’s datasheet.
A breadboard is not suitable for Inductors DCR measurement as the breadboard connection also contributes to noise and resistance.
It is good to use proper PCB with only test points, Current in and out connectors and the component pads component holding fixture to avoid soldering.
of an Inductor.
The Inductor shown here is an ideal Inductor and the DC Resistance is the equivalent series resistance.
The sense line is the Kelvin sense lines.
Let’s assume that the Inductor used here has a continuous current rating of 1A.
So we the input current here will be 1A.
Higher the value of input current higher will be the resolution of the measured DCR value, but if your inductor cannot handle high current low value currents can also be used.
After passing the current the voltage drop across the leads of the inductor has to be measured.
Suppose the voltage drop across the inductor is calculated at approx 50mV.
Then, the DCR of that inductor can be calculated as
V = I x R
R = V / I
R = 0.05 / 1
R = 0.05 ohm
How to reduce the DCR while constructing the Inductor
has no significant advantage and hence it is always better to select an Inductor with low DCR value.
Normally when Inductors are being constructed or designed, the DCR parameter is also considered.
DCR of an inductor needs to be very low so that the inductor does not block the DC current flow.
The following techniques are used to reduce the DCR value of a inductor
will have a low equivalent resistance as output.
of the copper wire decreases the DC resistance of the inductors.
Therefore, thicker wires are beneficial for reduced DCR.
instead of the round copper wires.
Flat wires have a large area compared with the round wires.
This is also beneficial to reduce the overall resistance.
The below image is an inductor which is constructed using flat wire.
The manufacturer is Wurth Electronics and the part number is 7443641000.
As per the datasheet, the inductor has an inductance of 10uH and the DC resistance is 2.4 mili-ohms at 20 degree Celsius.
to operate them in the minimum DCR value region.
SoDCRof an inductor is an important factor and should be considered while designing any circuit.
tutorial/what-is-power-factor-and-how-it-affects-your-energy-bills
Understanding Power Factor and How It Affects your Energy Bills
by a load and how much power it is “wastingᾮ As trivial as its name sounds, it is one of the major factors behind high electricity bills and power failures.
To be able to properly describe power factor and its practical significance, it is important to refresh your memory about the different types of electrical loads and components of Power that exist.
From basic electricity classes, electrical loads are typically of two types;
Resistive Loads
Reactive Loads
1. Resistive Loads
A good example of resistive loads includes incandescent light bulbs and batteries.
to understand how AC power works.
2. Reactive loads
This is dues to the nature of the Reactive Loads.
, as such, a phase difference usually exists between the current and the voltage.
, namely;
Actual Power
Reactive Power
Apparent Power
1. Actual Power
(along with its multipliers, kilo, Mega, etc.) and symbolically represented by the letter P.
2. Reactive Power
3. Apparent Power
, this total power is also called as Apparent Power.
The apparent power is given by the sum of the Actual power and reactive power.
Its unit is volt-amps (VA) and represented mathematically by the equation;
Apparent Power = Actual Power + Reactive power
drawn using the three Power Components
This vector diagram can be transformed into the power triangle as shown below.
is given below
P.F.
= Actual Power / Apparent Power or P.F.
= Cos
Putting this side by side with the equation for determining apparent power, it's easy to see that an increase in reactive power (presence of a high number of reactive loads), leads to an increase in apparent power and a larger value for angle , which ultimately results in a low power factor when its cosine (cos ) is obtained.
On the flip side, reduction in reactive loads (reactive power) leads to an increased power factor, indicating high efficiency in systems with less reactive loads and vice versa.
The value of Power Factor will always be between the value of 0 and 1, the closer it gets to one the higher will be the efficiency of the system.
In India the ideal power factor value is considered to be 0.8.
The value of power factor has no unit.
Importance of Power Factor
as both the real power required by the load and the reactive power used to satisfy reactive loads will be drawn from the system.
This strain and “wastageᾠtypically leads to huge electricity bills for consumers(especially industrial consumers) as utility companies calculate consumption in terms of apparent power, as such, they end up paying for power which was not used to achieve any “meaningfulᾠwork.
Some companies also fine their consumers if they draw more reactive power since it causes an overload on the system.
This fine is imposed so as to reduce low power factor causing loads being used in industries.
Even in situations where the power is being provided by the company’s generators, money is wasted on bigger generators, larger sized cables, etc required to provide power when a good number of it is just going to be wasted.
To better understand this, consider the below example
A factory operating a 70kW load could be powered successfully by a Generator/ Transformer and cables rated for 70 kVA if the factory is operating with a power factor of 1.
But, if the power factor drops down to 0.6 then even with the same load of 70KW, a larger generator or transformer rated for 116.67 kVA(70/0.6)will be required, as the generator/transformer will have to supply the additional power for the reactive load.
Asides this heavy rise in power requirements, the size of the cables used would also need to be increased, leading to a significant increase in equipment cost and increased power losses as a result of the resistance along the conductors.
The punishment for this goes beyond high electricity bills in some countries, as companies with poor power factor usually get fined huge sums to encourage rectification.
Improving the Power Factor
With all that has been said, you will agree with me that it makes more economic sense to rectify the poor power factor than to keep paying huge electricity bills, especially for large industries.
It is also estimated that over 40% on electricity bills can be saved in huge industries and manufacturing plants if the power factor is corrected and kept low.
Aside from the reduction in cost for consumers, running an efficient system contributes to the overall reliability and efficiency of the power grid, as utility companies are able to reduce losses in lines and cost of maintenance while also experiencing a reduction in the amount of transformers and similar support infrastructure required for their operations.
Calculating Power Factor for your Load
The first step to correcting the power factor is determining the power factor for your load.
This can be done by;
1. Calculating the reactive power using the reactance details of the load
2. Determining the real power being dissipated by the load and combining it with the apparent power to obtain the power factor.
3. The use of the power factor meter.
The power factor meter is mostly used as it helps to easily obtain the power factor in large system setups, where determining the reactance details of the load and the real power dissipated, may be a difficult route.
With the power factor known you can then proceed to correct it, adjusting it as close as possible to 1.nThe Recommended power factor by electricity supply companies, is usually between 0.8 and 1 and this can only be achieved if you are running an almost purely resistive load or the inductive reactance (load) in the system is equal to the capacitance reactance as they both will cancel each other out.
through the use of correction capacitors which introduce capacitive reactance in the system.
Power factor correction capacitors act as a reactive current generator, countering / offsetting the power being “wastedᾠby inductive loads.
However, careful design consideration needs to be made when inserting these capacitors in setups to ensure smooth operation with equipment like variable speed drives and an effective balance with cost.
Depending on the facility, and load distribution, the design could comprise of fixed value capacitors installed at inductive load points or automatic correction capacitor banks installed on the bus bars of distribution panels for a centralized correction which is usually more cost effective in large systems.
The use of power factor correction capacitors in setups has its downsides, especially when the right capacitors are not used or the system is not properly designed.
The use of the capacitors could produce some brief period of “over-voltageᾬ when turned on, which could affect proper functioning of equipment like variable speed drives, causing them to go off intermittently or blowing up the fuses on some of the capacitors.
It could, however, be solved by trying to make adjustments to the switching control sequence, in the case of speed drives or eliminating harmonic currents in the case of fuses.
Unity Power Factor and why it’s not practical
articles.
Power factor is a determinant of how well you are using energy and how much you pay in electricity bills (especially for industries).
By extension, it is major contributor to operational cost and could be that factor behind reduced profit margins that you have not been paying attention to.
Improving the power factor of your electrical system could help reduce electricity bills and ensure performance is maximized.
interview/ottomate-reinventing-home-appliances-through-ble-50-mesh-technology-puravansh-maitreya-dgm-of-marketing
Ottomate Re-inventing home appliances through BLE 5.0 Mesh Technology ᾠPuravansh Maitreya DGM of Marketing
which have built in sensors to automatically change the fan speed based on room temperature.Drawn by its features and capabilities CircuitDigest approached Ottomate with few questions to know more about Ottomoate for which the company'smarketing DGM Mr.
Puravansh, responded with the following
Our Founder Mr.
Vishal who is also the founder of Lava International, which is a billion dollar Phone manufacturing company in India, realized that the technological development with Phones, TVs and Tablets are happening very fast around us.
But, the electrical appliances in our home like Fans, Lights, and Geysers etc are not yet that engaging and smart enough because the technology here has not evolved much in the recent years.
To address this problem Ottomate was launched to provide smart home devices and appliances.
By leveraging our background in electronics and deep relationships with leading chip manufacturers like Qualcomm, Texas Instruments etc the company has already gone live on March 2019 with first product being a Smart Fan.
We also have other home appliances in our pipeline and can be expected to be launched soon.
Our aim is to make the traditional home appliances smart by connecting the entire home on your mobile phone so that they can be controlled form one device.
Installing Ottomate products will be simple as you don’t have to do your wiring again or change anything on your switch panel.
Also, since our products work on BLE Mesh technology they also do not need to need Wi-Fi Routers.
All our products can be controlled through our mobile application and as new products are purchased and installed they will be automatically connected to the same application eventually allowing the user to control all our products from a single application.
Our fans have a special mode called “Otto Modeᾠin which the fan measurers the temperature and humidity present in the room and changes its speed accordingly.
As would have realized that temperature variations happen throughout the day, days are hot and nights are cold.
We might have also come across the annoying necessity to slow down our fans or catch a blanket early in the morning since the temperature would have gone down from what it was in the night.
To address this problem Ottomate has introduced automatic speed control technology.
The Fan Measures the Temperature and Humidity value in the room by using its in-built sensors and then using the algorithm developed by our R&D engineers the fan determines the optimum speed for that temperature and humidity level and adjusts its speed accordingly.
No, Ottomoate Fans do not consume more electricity than Traditional fans.
Most fans out there consume about 70 to 80 Watts power and ottomate fans are also rated for 75 Watts.
Also we are in plans to launch an energy efficient series in the month of June this year.
Speaking about Lifespan the fans come with 2 year warranty, just like any other fan in the market.
And we expect its life for about 5 to 10 years easily.
All Ottomate products will work on BLE 5.0 Mesh Technology.
We realized that most of the home appliances are operated within the home which does not need Wi-Fi also by this way we can eliminate the extra cost of router installation.
Bluetooth 5.0 has very significant range that could cut across through three floors in a multistory home and across multiple walls.
The advantage of having a Mesh network is that, all the Ottomoate products are connected together capable exchanging information among them.
This way the user just has to be in range of any one of our product and still he can access any of them since they all are interconnected.
If the user wishes to control his appliances outside from his home, he can use our cost effective BLE to Wi-Fi converter to connect all the appliances to the internet through his Wi-Fi Router.
Normal fans come with 5 speed mechanical regulators which allow the user to have only five speed levels.
In Ottomate fans the speed is controlled by solid state devices like MOSFETs which provides the user with multiple speed levels.
The air delivery of our fan can be adjusted to very minute level by adjusting the slider on our application.
The ability to have a fine control on speed is what we called the My Air Technology.
To deal with Power Quality issues we are using the Voltage converters from ST Microelectronics which comes with in-built Voltage Stabilizers.
The Voltage is run though a dummy circuit to check for fulminations before it reaches the motor and control circuitry.
This work is taken care by the Voltage Stabilization chip.
from Qualcomm supports ultra low power Bluetooth 5.0 Technology with Mesh Connectivity.
Since all Ottomate Fans have to be connected to the BLE Mesh network the processor would ideally suit our designs.
Ottomate is a completely made in India product.
We have two plants, one in Himachal and the other one in Rishikesh.
We have a good relationship with Qualcomm, ST, Toshibaetc.
who are our suppliers for Ottomate.
Since LAVA already was working closely with these suppliers it was easy to set-up the supply chian for Ottomate.
Currently we are also working on Lights, Security Sysetms and Geysers.
In another two to three years down the line you can expect more larger appliances from Ottomate.
tutorial/understanding-esr-and-esl-in-capacitors
Understanding ESR and ESL in Capacitors
, which we call as the parasitic resistance or parasitic inductance.
Yes, just like a parasite this unwanted resistance and inductance properties sits inside a capacitor preventing it from behaving like a pure capacitor.
The value of this inductance and resistance will be very small, that it can be neglected in simple designs.
But in some high power or high frequency application these value can be very crucial and if not considered might reduce the component efficiency or output unexpected results.
which we will discuss in another article some other time.
ESR in Capacitors
of the capacitor.
The equivalent series resistance or ESR in a capacitor is the internal resistance that appears in series with the capacitance of the device.
The capacitor symbol is representing the ideal capacitor and the resistor as an equivalent series resistance.
The resistor is connected in series with the capacitor.
This resistance comes from the dielectric material, leakage in an insulator or in the separator.
Adding to this, Equivalent series resistance or ESR will have different values in different types of capacitors based on its capacitance value and construction.
Hence we have to measure the value of this ESR practically to analyze the complete characteristics of a capacitor.
Measuring ESR in Capacitors
across the capacitor.
Based on the change in frequency of the signal the ESR value of the capacitor can be calculated.
An advantage with this method is that, since the ESR is measured directly across the two terminals of a capacitor it can be measured without de-soldering it from the circuit board.
is shown below
The Vs is the sine wave source and R1 is the internal resistance.
The capacitor C is the Ideal capacitor whereas the R2 is the Equivalent Series Resistance of the ideal capacitor C.
One thing needs to be remembered is that in this ESR measurement model, the capacitor’s lead inductance is ignored and it is not considered as a part of the circuit.
of this circuit can be depicted in the below formula-
In the above equation, the high pass feature of the circuit is reflected; the approximation of the transfer function can further be evaluated as ᾍ
H(s) ≈ R2 / (R2 + R1) ≈ R2 / R1
The above approximation is suitable for high-frequency operations.
At this point, the circuit starts to attenuate and act as an attenuator.
The attenuation factor can be expressed as ᾍ
= R2 / (R2 + R1)
This attenuation factor and the sine wave generator’s internal resistance R1 can be used to measure the capacitors ESR.
R2 = x R1
can be useful to calculate the ESR of the capacitors.
Normally, ESR value ranges from a few milliohms to several ohms.
Aluminum electrolytic and tantalum capacitors have high ESR compared with the box type or ceramic capacitors.
However, modern advancement in capacitor manufacturing technology makes it possible to manufacture super low ESR capacitors.
How ESR affects the Performance of Capacitor
in high current application and the capacitor life decrease eventually, which also contributes to the malfunction in electronics circuits.
In power supplies, where high current is a concern, the low ESR capacitors are required for filtration purposes.
Not only in power supply related operations but low ESR value, is also essential for the high-speed circuit.
In very high operating frequencies, typically ranging from hundreds of MHz to several GHz, ESR of the capacitor plays a vital role in power delivery factors.
ESL in capacitor
shown below.
The capacitor C is the ideal capacitor and the inductor L is the series inductance connected in series with the ideal capacitor.
; increase in current loop also increases the ESL in capacitors.
The distance between the lead termination and circuit connecting point (including pads or tracks) also influences the ESL in capacitors because increased termination distance also increases the current loop resulting in high Equivalent series inductance.
Measuring ESL of a capacitor
At this point, the capacitor self resonates.
The ESR of the capacitor contributes to flatten out the impedance plot till capacitor reached the ‘kneeᾠspot or at the self-resonating frequency.
After the knee point, the capacitor impedance starts to increase due to the ESL of the capacitor.
of a MLCC (Multi layer ceramic capacitor).
Three capacitors, 100nF, 1nF X7R class and 1nF of NP0 class capacitors are shown.
The ‘kneeᾠspots can easily be identified across the lower point of V shaped plot.
Once the knee point frequency is identified, the ESL can be measured by the below formula
Frequency = 1 / (2π↨ESL x C))
How ESL affects the Capacitor Output
, making the circuit to behave odd.
Practical importance of ESR and ESL
Combining these three the real capacitor is made.
R where R is the ESR value.
Not only this, noises and high voltage drop also occur due to high ESR value as per the Ohms law.
Modern capacitor manufacturing technology reduces the ESR and ESL value of the capacitor.
A huge improvement can be seen in today’s SMD versions of multilayer capacitors.
ranging from hundreds of kHz.
Because of this the input capacitor and the output filter capacitors need to be in low ESR value so that the Low-frequency ripples has no effects in the overall performance of the power supply unit.
The ESL of the capacitors also needs to be low, so that the impedance of the capacitor does not interact with the power supply switching frequency.
In a low noise power supply, where the noises need to be suppressed and the output filter stages should be low in numbers, high quality super low ESR and low ESL capacitors are useful for smooth output and stable power delivery to the Load.
In such an application, polymer electrolytes are a suitable choice and commonly preferred over Aluminum Electrolytic capacitors.
article/robotic-end-of-arm-tools-tighten-their-grip-over-automation-setup
Robotic End of Arm Tools Tighten their Grip over the Automation Set-up
Robots are taking over the global manufacturing landscape.
The trend of robotic process automation has purveyed enormously across a wide range of industries, including automotive, semiconductor & electronics, and pharmaceuticals industries.
In the food & beverage industry, robots are processing, packing, and moving food products to eliminate contamination from human contact.
In the electronics industry, robots are employed to process and handle delicate semiconductor wafers in miniaturized electronic circuits.
Robots also play a critical role in laboratories to transport microtiter plates between instruments and are used in cleanroom procedures in the pharmaceutical industry.
have expanded the range of their industrial applications as an integral part of industrial robots and automation.
recorded the sales of over US$ 1.9 billion in 2018 and is expected to witness exponential growth in the coming years.
Leading players in the market are launching robotic end of arm tools that are faster, safer, and more efficient to tap the potential of robotics in industrial automation.
Robotic Penetration: Linchpin for the Robotic End of Arm Tools Market
The increasing prevalence of robots across the industrial landscape is anything but fortuitous.
The ubiquity of industrial automation is triggered by the constant pressure to improve business productivity and cut production costs, and robots are slowing taking over a multitude of human operations, both complex and tedious, in manufacturing industries.
Studies have found that a little more than two million industrial robots were employed on factory plants and various commercial locations across the world, in 2017, and the number is likely to cross three million by the end of 2020.
Thereby, increasing penetration of industrial robots will pave the way for the future of robotic end of arm tools industry in the coming years.
Advancements Underpinned by Increased End-user Demand for Greater Dexterity and Flexibility
The robotic end of arm tools landscape is witnessing a new trend where applications and end-user needs dictate the designs of grippers, welding torches, and end-effectors.
Industrial automation has seen sheer proliferation with the emergence of the trend Industry 4.0 and leading companies are adopting strategies to sync with the dynamic end-user requirements and maintain the lead in the intensified competitive landscape of the market.
Leading manufacturers in the robotic end of arm tools market are taking up the gauntlet to further enhance the operational capabilities of industrial robots.
The constant need for reducing operating costs and improving dexterity and precision is driving manufacturers to shift focus on launching innovative features of robotic end of arm tools.
In addition, end-user demand for greater production flexibility and reliability is triggering the adoption of next-generation technologies among robotic end of arm tool market players.
Increasing concerns about robot safety among end-users are attributed for the rise in adoption of safer grippers integrated with sensors that have force limitations that can ensure safety of a human worker around robots.
Furthermore, growing demand for grippers or end-effectors that can handle same materials in multiple sizes or different types of materials redefine the emergence of the flexibility trend in the robotic end of arm tools market.
The food & beverage industry has been triggering demand for soft grippers that are delicate and flexible enough to be used in food processing and packaging applications without causing damage to the end-product.
Manufacturers are also launching connected end of arm tools to meet the increasing end-user requirements for better human-robot interaction.
With the launch of smart and connected grippers and end-effectors, market players are enabling end-users to improve the communication between robotic end of arm tools and other smart components in the automation system.
Smarter and more versatile grippers, end-effectors, and other types of robotic end of arm tools are expected to witness burgeoning demand in the industrial landscape, in the upcoming years.
The Rise of Collaborative Robots Raises the Bar for Innovation
are known to be a lot safer than conventional robots used in automation, as they can detect an obstacle with sensitive force monitoring capability, and thereby, are usually operated unguarded around human workers in an industrial environment.
Increasing popularity and applications of cobots in industrial automation is opening new avenues of growth for robotic end of arm tool manufacturers.
Growing presence of cobots spread across industries is triggering the need for making them smarter, safer, and more reliable.
As robotic end of arm tools are becoming the workhorse of the automation ecosystem, they are getting special attention for maintaining collaborative status of cobots.
Leading manufacturers of end of arm tool are focusing on launching smart, collaborative robotic sensors, grippers, and quick changers that can be integrated with cobots.
Ongoing efforts to establish an effective human-robot collaboration is indicative of a predominant trend in the robotics industry, and consequently, cobots will remain an imperative component in industrial automation in the upcoming years.
The International Federation of Robotics (IFR) projects that cobots will emerge as the fastest-growing segment in the industrial automation industry, accounting for over one-third share in the robot sales across globe in 2025.
The potential rise in the sales of cobots will provide an impetus to innovation in robotic end of arm tools market in the coming years.
Gripper Technology to Witness Burgeoning Adoption
Grippers have remained high in demand as one of the most used robotic end of arm tools in a wide range of industrial applications.
In 2018, grippers recorded the global sales of over US$ 1 billion and accounted for more than half the revenue share of the robotic end of arm tools market, and the trend is likely to prevail in the coming decade.
Manufactures are shifting focus towards research & development activities to incorporate advanced gripper technologies and capitalize on the trend of growing adoption of grippers in the industrial automation landscape.
Incorporation of gripper technology is increasing in gripper designing as hybrid robotic end of arm tooling trend is spreading rapidly across industries.
Manufacturers are combining multiple gripper technologies in a single robotic end of arm tool, as end-users are pushing the need to a universal gripper that can be compatible for various types of materials.
In addition, the growing popularity of parallel motion 2-jaw grippers, 3-jaw grippers, as well as electric grippers, will influence salient business strategies of leading companies in the robotic end of arm tools market in the upcoming years.
Manufacturers are incorporating advanced gripper technologies in complex as well as simple gripper variations; yet the main rule of thumb for manufacturers is to maintain safety, simplicity of technology and ease of use.
With the overwhelming abundance of advanced robotic end of arm tools available on the market, end-users will remain more inclined towards flexible, cost-effective, and dexterous variants.
Thereby, achieving more simplicity and flexibility by the virtue of next-generation gripper technologies will ultimately play a critical part in manufacturersᾠbusiness strategies to gain an edge in the robotics end of arm tools market.
Developing Countries in Asia to Remain Revenue Packets for Manufacturers
The market for robotic end of arm tools in the Asia Pacific region, excluding Japan, (APEJ) has been growing exponentially as the industrial landscape in developing countries is seeing a sea change with the emergence of technologies.
Though the European Union is currently witnessing a rise in demand for cobots in various industrial sectors, the Asia Pacific area is leading the rally in industrial automation ecosystem, thanks to growing investment in Industry 4.0.
In 2018, sales of robotic end of arm tools in APEJ accounted for more than 51% revenue share of the global market, and increasing growth of the automotive industry was the primary driving engine in the region.
The adoption of industrial automation has remained the highest in the automotive industry, not only in APEJ but across the world, and this will continue to impact the design of robotic end of arm tools being launched in the market throughout the next decade.
article/electric-vehicle-on-board-chargers-and-charging-stations
Electric Vehicle On-board Chargers and Charging Stations
(EVs) despite being a greener, smoother and cheaper mode of transport does not seem to be practical yet.
The reason is two words, Cost and Ecosystem.
Currently EV’s are priced substantially at par with Gasoline cars making it a less significant choice for buyers, the advancement in battery technology and government schemes are expected to bring down the cost of EV in Future.
The second part would be, there is no proper ecosystem for the buyers to use an Electric Vehicle without much hassle.
With “EcosystemᾠI am referring to the charging stations to charge your EV when you run out of battery juice.
Imagine using a gasoline vehicle when you have no gas stations in your town and the only place you can refill is you home, adding to that you will need a minimum of 6-8 hours to charge a typical EV.
Many companies like Tesla, EVgo, charge point etc have already acknowledged this problem by setting up charging stations around the country.
With countries like Netherland, who promised to give up petrol engine by 2035 it is sure that the roads of future will be replaced with EVs over internal combustion engines and a lot of EV charging stations would pop up around us.
Electric Vehicle Supply Equipment (EVSE)
The term is more popular, and it refers nothing but to the charging stations.
Some people also refer it as ECS which stands for Electric charging station.
An EVSE is designed and engineered to charge a battery pack by using the grid for Power Delivery; these battery packs might be present in an Electric Vehicle (EV) or in a Plug-in Electric Vehicle (PEV).
The power, connector and protocol for these EVSE will vary based on it design which we will discuss in this article.
On-Board Chargers and Charging Stations
) and the manufacturer also provides a Charger along with the vehicle.
These chargers along with the on-board charger can be used by the customer to charge his EV from his house power outlet as soon as he/she gets it home.
But these chargers are very basic and do not come with any advanced features and hence would normally take around 8 hours to charge a typical EV.
Types of EV Charging Stations (EVSE)
Charging Stations can be broadly classified into two types, AC charging Station and DC charging Station.
is its low output power which increase the charging time.
A typical AC charging system is show in the below picture.
As we can see the AC from grid is supplied directly to OBC through EVSE, the OBC then converts it to DC and chargers the battery through the BMS.
The Pilot wire is used to sense the type of charger connected to the EV and set the required input current for the OBC.
We will discuss more on this later.
where it needs to communicate with EV to charge it efficiently and safely.
A typical DC charging system is shown below, as you can see the EVSE provides DC directly to Battery pack bypassing the OBS.
The EVSE is arranged in stacks to provide high current a single stack will not be able to provide high current due to power switch limitations.
are meant for public charging stations alone.
They require poly phase AC input from the grid and consume more than 240 kW which almost 10 times more than a typical Air conditioning unit in our home.
So these chargers require special permission from the grid to operate.
since the AC/DC and DC/DC conversion takes place in the EVSE itself.
Because of the huge size and complexity of a Level 2 and Level 3 chargers they cannot be built inside a EV as it would increase the weight and reduce the efficiency of the EV.
AC charging Station
Level 1 - Residential
Single Phase ᾠ120/230V and ~12 to 16A
~1.44 kW to ~1.92kW
~ 17 Hours
AC charging Station
Level 2 - Commercial
Split Phase ᾠ208/240V and ~15 to 80A
~3.1 kW to ~19.2 kW
~ 8 Hours
DC charging Station
Level 3 ᾠSupercharger
Single Phase ᾠ300/600V and ~400A
~120 kW to ~240 kW
~ 30 minutes
Types of EV Charging Connectors
Just like the Europeans operate at 220V 50Hz and the Americans operate at 110V 60Hz the EVs also have different types of charging connectors based on the country it is manufactured form.
This has lead to confusion among ESVE manufacturers as they cannot be made universal easily for all EVs.
The main classifications of Connectors for AC chargers and DC chargers is given below.
:
with is popular in North America.
As you can see the Plug /connector have multiple connections the three broad pins are for Phase, Neutral and Ground while the two small pins are used for communication between the Charger and the EV (Pilot Interface), we will discuss more about this later.
The Mennekes or VDE-AR-E is used in Europe for three phase AC charging system and hence can output high power upto 44kW.
The Le-Grand is also a similar socket with safety shutter to prevent debris from entering the charging socket.
According to technical standards only the HSAE 1772 and the VDE-AR-E sockets are suggested to be used in all AC chargers of future.
:
which is the most popular type of socket.
It was introduced by Japan and soon adapted by France and Korea.
Today most EVs like the Nissan Leaf, Kia etc have these types of sockets.
The socket has two broad pins for the DC power rails and communication pins for CAN protocol.
As we know Level 3 DC chargers do not use the on-board charger and hence have to provide the required voltage and current for the battery pack of the EV by itself.
This is done by establishing a communication link (Pilot link) though Control Area Network (CAN) protocol with the BMS of the battery pack.
The BMS then instructs the Charger to begin the charging process, monitors it and then requests the charger to stop charging.
and hence have their own type of connectors as shown above.
But they do sell an adapter which can convert their port to be charged with CHAdeMO or CSS chargers.
The CDD charger is another popular charger socket which combines both AC and DC types of chargers.
As you can see in the image he charger is split into two segments to support both DC and AC.
It can support CAN and Power Line Communication (PLC) and is widely used in European Cars like Audi, BMW, Ford, GM, Porsche etc.
It can support upto 400kW DC output and 43kW AC output.
EVSE AC Charging Station - Level 1 and Level 2 Chargers
is shown below.
when operated in Three Phase supply.
Both the Level 1 and Level 2 AC chargers normally use the SAEJ1772 standard plug connectors.
though a Relay.
This relay will be closed to begin the charging process and opened when charging is completed.
The Pilot Signal communication is used to detect battery status and the host processing system decides how much power should be supplied to the on-board charger.
We will discuss more on this later.
(CT) is used to measure the input current but shunt or Flux method can also be used.
The voltage is measured on either side of the relay to know if the relay is current open or closed.
Since the measurement subsystem deals with AC voltage and current it is digitally isolated from the Host Processing Subsystem.
consists of the main Microcontroller which receives the information from pilot communication and based on the information it triggers the Relay using Relay driver circuits.
It also monitors the current and voltage using the values provided by measurement subsystem and takes corrective actions whenever required.
This controller will also have a display unit, EEPROM and RTC to provide useful information like charging time, current status etc to the user.
Pilot Wire Communication in EVSE (AC charger)
signals.
By default the signal pins on the EVSE output +12V, this when connected to an EV will get reduced to 9V because of a load resistor present in the Electric Vehicle, this signals the EVSE that the connector has been plugged into a EV.
After this the EVSE will send a PWM signal of magnitude 12V and a duty cycle value corresponding to the maximum current it could deliver.
If the EV is okay with that value of current then it performs a handshake by changing the load resistance and dropping the PWM voltage to 6V after which the charging begins.
meaning the available input current is 30A (Maximum capacity 60A).
If the EVs on-board charger could work with this current then the EV signals a handshake by changing the load resistance and the PWM signal now drops to 6V.
The charging begins at this point and will continue as long as the PWM signal oscillates between 6V and -12V.
The EV will change its load resistance again when the charging process is complete to signal the charger to shut down.
EVSE DC Charging Station - Level 3 Chargers
The level three charging stations are more complex than the Level 1 and Level 2 since the DC/DC conversion for the battery pack has to be done by the EVSE itself.
Since a DC EVSE bypasses the on-board charger it should know all vital parameters of the battery pack to charge it safely hence a CAN or PLC (Power Line Communication) should be established between a EVSE and the BMS of the EV.
A Level 3 charger normally uses the CHAdeMO charger socket but other connectors like the J1772 Combined charging connector, Tesla connector are also being adapted by different manufacturers, these chargers can deliver upto 200A directly to your battery pack to charge the EV in less than 30 minutes.
A typical simplified DC charging station Subsystem block diagram is shown below.
arrangement gets mandatory.
Some EVSE will also have wireless features like NFC, Bluetooth and Online payment gateway features etc to facilitate easy public usage.
cannot handle as a single unit.
Hence normally the converter units are split into small units which are then combined in parallel to provide high current.
Advancements in EVSE
are slowly getting popular.
Due to the size, efficiency and weight of solar panel it is not possible to have EV’s directly run by solar power.
But EVSE on the other hand can draw power from the Solar panel instead of grid.
The downside though is huge initial cost and poor efficiency, since the power from solar has to be stored in batteries and then have to be transferred to EVs again.
Also the efficiency of solar panel is very low (44.5% is the highest till date) and its technology still has to be developed to make it a affordable upgrade.
system.
Wherein the Battery Pack in a EV could act a Power source for household equipments.
Today’s EVs come with a huge battery pack upto 100kWh or more making it an easy portable power house.
So with the right inverter the power from these battery packs can be supplied to the grid during peak demand hours.
Then these EVs can be driven to Solar powered stations to get them charged again, building a completely green eco system.
Setting up an Electric Vehicle Charging Station in India
With EVs getting quickly popular in India, we can already notice many EVSE set-ups popping up in major cities of India.
With regulations still being standardized for India the following are the common problems with setting up an EVSE in India.
The EVs in India are still not ready for Level 3 or Super chargers as their battery packs do not support fast charging.
How fast a battery could charge depends on its C rating, Indian EVs still have very low C rating that even a Level 2 charger is not required for most EVs.
This will create less demand for public EVSE
According to norms you are not allowed for direct Re-Sale of electricity.
Only the DISCOM is allowed to sell electricity.
However with pressure from ISGF the Charging stations might be considered as an expectation for this in the future.
to know more details about setting up an EV charging station in India.
article/top-10-open-source-iot-platforms-to-cut-down-your-iot-development-cost
Top Open Source IoT Platforms to Cut Down Your IoT Development Cost
is no longer a buzz word that’s thrown around by experts.
It is Real!! And can be found all around us, changing lives, facilitating better services, improving processes, providing new opportunities and increasing revenues.
With billions of new devices that are yet to be connected to the internet, the impact of IoT will definitely be driven beyond the IoT devices themselves to several other applications by leveraging the data provided by these devices to achieve social and commercial growths.
This is already happening as most organizations today that don’t have IoT solutions deployed, are still able to reap the benefits of it by getting access to the data generated by devices deployed by other people by using their APIs.
What is an API and how is it useful?
, allowing applications written in one language to be used by software written in another language, helping in reduction of overall infrastructure and time requirement for product development.
These same advantages are currently being transferred into IoT applications with APIs being used across diverse application to expose data that enables multiple devices to be combined and connected to solve new and interesting workflows, revealing unseen possibilities around IoT.
These are nothing but APIs provided by Google/Facebook to Spotify to make the signing up procedure easy.
Here the API will share basic user details like Name, E-mail ID, Phone number etc with Spotify and help you in saving time with signing up procedure.
Likewise different APIs are available for different application needs.
1. OpenHAB REST API
and “not-so-smartᾠhome devices in one place.
It allows the performance of user-defined actions by devices, using user-defined information and user-defined tools.
To achieve this, openHAB segments and compartmentalizes certain functions and operations all of which could be accessed through the openHAB REST API.
; as such it is important to ensure secure and safe connections when working with it.
According to the openHAB website, some of the interactions possible via the openHAB REST API include;
Retrieve openHAB data from external applications
Inject data and trigger events in openHAB from external applications (for example, some motion detectors or surveillance cameras)
Inspect openHAB Bindings/Things or Items, learn about current states, parameters or problems
Interacting with openHAB from other programs; many programming languages and automation tools can easily make use of REST API
Using third party software on cell phones, such as Tasker to open your garage door
Third party apps like Tasker being used with openHAB is a big pointer to how APIs are opening up the IoT economics, providing opportunities for additional value creation along the chain.
2.Mozilla Web Things API
on the World Wide Web, allowing it to be used as a unifying application layer for all the IoT devices.
3. OpenWeatherMap
The data is processed and sorted in such a way that via the OpenWeatherMap API, IoT solutions which leverage these data to inform and automate tasks can be built.
For instance, forecast data via the API can be fed into an alarm system/device to warn farmers of possible heavy downpour among several other possibilities.
4. EmonCMS API
sensors can be viewed.
To make it easy for developers to access the platform, a connectivity API was created to allow interaction with the platform when running on localhost (LAN) or via the internet.
The EmonCMS API allows users update the status of energy devices on the platform, obtain readings and other parameters indicating the state of devices (if the device is compatible) from the platform along with several other features.
purposes.
The Particle API makes it easy for developers to access and integrate the full functionality of Particle with other applications and devices.
According to particle, the API allows developers to write functions to their device's firmware and then call them for use in on the application side of things in real-time.
Some example API methods include turning the wifi off and on, connecting devices, toggling the state of the devices, obtaining data and generally managing the devices.
6. Adafruit IO API
as well.
, The Adafruit IO HTTP API provides users with access to their Adafruit IO data from any programming language or hardware environment that can speak HTTP.
Through this they can design systems that take action based on the data, and effect changes in the device by sending information to the devices.
7. Home Assistant API
similar to openHAB.
Like other platforms, Home Assistant is driven by the Home Assistant Python REST API which provides access to data methods for the Home Assistant control service.
8. The Things Network APIs
.
9. ThingSpeak.io REST API
where ThingSpeak has been used with many different microcontrollers like Arduino, Raspberry PI, ESP etc:
Live Temperature and Humidity Monitoring over Internet using Arduino and ThingSpeakHeart Beat Monitoring over Internet using Arduino and ThingSpeakRaspberry Pi Weather Station: Monitoring Humidity, Temperature and Pressure over InternetIoT Based Patient Monitoring System using ESP8266 and Arduino
Some of the features of ThingSpeak which automatically translate to benefits of using it’s API are;
Easy device configuration to transmit data to the ThingSpeak platform using standard IoT platforms.
Real-time visualization of sensor data and data aggregation using third party sources.
IoT analytics runs based on schedules or events.
MATLAB analytics, RESTful and MQTT APIs.
Enables the prototyping and building of IoT systems without any server setup and Web software installation.
Compatibility with popular development platforms like the Arduino and Raspberry Pi
Automatically acts on data and automate tasks
Integration with third party services like Twitter.
A good example of a situation where this is a useful is an IoT solution that automatically tweets water level.
In addition to the free hosted API, the ThingSpeak API is open source and available on GitHub for download on private servers.
10.
EdgeX Foundry
The API has a REST architecture and uses OAuth 2.0 for authentication.
Edgex has a series of micro service which are attached to each device connected to the network.
Each micro service has several important API calls that can be used to;
Register a device service
Provision a Device
Send data from device to the Edgex platform,
Reading the data from the Edgex platform for use in other applications
Exporting data, amongst others.
and others that I could have added to the list are coming to mind.
Feel free to drop comments about the Open IoT APIs that you have worked with.
Your comments may go a long way in helping others select an API or platform to use in their projects.
Till Next time.
interview/dhivik-founder-and-ceo-of-go-greeneot-shares-how-his-company-is-building-energy-efficient-electric-two-wheelers
Dhivik, Founder and CEO of Go GreenEOT shares how his company is building Energy efficient Electric Two-Wheelers
(Battery Operated Vehicles) with an aim of proving a comfortable two-wheeler that is elegant in looks, geeky in technology and a saint on the environment.
With its strong team and better understating of technology the company is confident in transforming the way energy is used or seen today.
Over the years the company has launched a wide variety of Electric vehicles and has worked closely with B2C segment and now is exploring tie-ups in B2B category with an assured reduction of last mile delivery cost upto 30%.
Curious to know more about the company,CircuitDigest approached Mr.
Dhivik, the Founder and CEO of Go GreenEOT.
Dhivik has over 11 years of experience in building companies and have been holding the helm of Go GreenBOV for more than 9 years now.
He was the only representative from India to be a part of Samsung SDI global contest and has worked over a month in the Samsung SDI plant that manufactures Lithium Cells in S.Korea.
His contribution towards the Energy Storage Space over these years, has won him an award from the president of India.
Q.
How has your journey with Go GreenEOT been, what is the company currently focusing on?
because they were way more cost effective compared with lithium batteries and also lithium was beyond the scope of Indian market considering its cost and availability.
The problem with lead acid batteries were that the energy output was only about 35 Watt-hour per kilo gram, because of this the weight of the battery was high and lower sized motor were used resulting in an under powered vehicle.
Now, with lithium batteries the biggest advantage is that you can generate high power with less battery weight allowing us to design high power electric vehicles.
After 2015 we were the first to change our business model from B2C to B2B because we realized that there is a market opportunity for EV 2Wheelers in India.
Currently we focus on the B2B segment like the delivery companies and along the way we have also made improvements to our battery life expectancy and temperature build up problems in battery packs considerably.
When I look at it, I think EV adaption in India is not going to be that very significant till 2025.
Because right now, if we were to compare an EV with a Honda Activa which is available for around Rs.70,000.
Activa can travel around with about 80 km/hr speed and can be easily re-fueled at multiple stations allowing us to cover more distance.
Adding to that, it can also carry heavy weight and provide a good pick-up.
Now when it comes to electric vehicle this is not the case, EV’s still require longer charging hours and on top of that lacks resale value compared with a conventional two wheeler.
A possible solution for this problem will be mass adaption, which results to reduction in costs and setting up of charging stations and the required infrastructure will be built.
To accelerate this mass adaption is why we began with the B2B segment.
These are reasons why Go GreenBOV currently concentrates more on the B2B section.
One of the main reasons why EV users end up getting lower mileage or lower battery life is the temperature build up inside the battery packs.
A good example can be given by considering an Android mobile phone.
The mobile phone is optimized to perform low power consumption work like making calls, sending text messages etc, but the moment we start using it extensively like for gaming purpose you can notice the battery getting hotter and draining faster than normal.
From this we can observe that battery drops much faster when it is hot.
For this Go GreenEOT has worked on a Battery cooling Air Flow technology using which we can control the temperature of the batteries.
With this technology the battery temperature increase only to about 6° to 8°C when it is being discharged from 100% to 0%.
This figure is much lower compared against the normal method in which the temperature rise can be upto 65°C with the delta of increase being 37°C.
With this we have seen the battery life increasing by about 1.2 times with a 30% to 40% improvement in the range.
Our goal is to first make a cost effective product and then proceed with improvising and perfecting it.
Finally in the end we deliver the refined product to our customers.
For this refinement process, we have developed a system which could get close to 217 parameters every second from our electric vehicle using which we have been able to improvise a lot in terms of battery life, range etc.
For the Connected things we believe it’s a two Way Street in which the customer gets benefited by knowing about his vehicle while the manufacturer also gets benefited by remotely monitoring the performance of his vehicle.
Establishing the supply chain was one of the biggest challenges we faced.
The companies have to look at it with a very long term approach.
After some research we understood that lot of components are either not available in India or priced high, hence it has to be sourced from elsewhere.
Slowly we have been able to do this by working closely with our existing suppliers and discussing our designs with them.
Today we have a well established supply chain including major vendors.
Getting the right type of cells for your EV is vital, and Go GreenBOV has invested a lot of effort and time into it.
We have visited the stock yards of our suppliers and taken into consideration the temperature layout, humidifier and dehumidifier used, date of chemical studies and much more before selecting the right battery vendor for us.
WE have been able to do a complete QPA of the manufacturing facility where close to around 400+ parameters are identified for long term life of the cell itself.
As far as lithium manufactures in India are considered, the on ground reality versus the off ground reality is quite harsh.
The big players are talking about manufacturing Lithium cells in India but no one seems to really get into it because of low demand.Also setting up a Lithium cell manufacturing plant will take about 2 years and another 2 years to begin production which is another reason why we don’t see any solid lithium manufacturers in India yet.
article/crystal-oscillator-vs-resonator
Crystal Oscillator Vs Resonator
Both of them have the same aim of generating an oscillation frequency by vibrating when an input voltage is given to them.
But they two have some differences too, which separates them & as a result, they have different applications.
What is Crystal Oscillator?
The symbol & circuit of a crystal oscillator is as shown below:
here.
What is a Ceramic Resonator?
is also an electronic circuit or a device used to generate an output of oscillation frequency with the help of Ceramic as a resonating piezoelectric material.
The material can have two or more electrode which when connected to an oscillator circuit gets mechanical vibration & as a result an oscillating signal of a specific frequency is generated.
The circuit for the resonator is similar to that of Crystal Oscillator and is as shown below:
When the resonator is working, the mechanical vibrations produce an oscillating voltage due to the piezoelectric material i.e.
ceramic and the oscillating voltage is then attached to the electrodes as output.
The inverse concept is used in case of inverse Piezoelectric effect.
Crystal Oscillator Vs Resonator
Though they both have the same working procedure & generate frequency oscillation as output, they have some difference in properties due to which the oscillator has replaced resonator in many cases, which are:
Frequency Range - The Crystal Oscillator has much high Q factor than that of Ceramic Resonator due to which Crystal Oscillator has a frequency range of 10 kHz ᾠ100 MHz range while the frequency range of ceramic resonator varies from 190 kHz ᾠ50 MHz
Output - Crystal Oscillator provides high stability frequency output and the Ceramic resonator also provides stability output not that good as compared to Crystal Oscillator.
In terms of output frequency accuracy, Crystal Oscillator provides much more accurate output than the Ceramic resonator for which parameters like temperature are a sensitive element.
The accuracy for the oscillator is 10ppm-1000ppm while for the resonator is 0.1% - 1%.
Effect due to Parameters - For Ceramic resonator, the thickness of the ceramic material would determine the output resonant frequency while for Crystal Oscillators the resonant frequency output depends on the size, shape, elasticity & speed of sound in the material.
The Crystal Oscillator has very low dependency on temperature i.e.
they are highly stable even with changes in temperature and the ceramic resonator have a little more dependency on temperature then Crystal Oscillator.
For a Quartz Crystal Oscillator, the output characteristics depends on the vibration mode and angle at which the crystal is cut while in resonator mainly the thickness matters.
Tolerance & Sensitivity - The Crystal Oscillator has less tolerance against shock & vibration while the ceramic resonator has a high tolerance comparatively.
Crystal oscillator has low ESD (Electrostatic Discharge) tolerance while the ceramic resonator has a high ESD tolerance.
Oscillators are more sensitive than the resonators, the sensitivity can be compared in terms of radiation.
Quartz has a 0.001% frequency tolerance, while PZT has a 0.5% tolerance.
Capacitor Dependency - Resonators may have internal capacitors or need external ones sometimes while the Oscillator needs external capacitors and their value depends on what crystal is designed to work with.
Material Used - Crystal Oscillator is made up of Quartz as the piezoelectric resonator material while Ceramic resonators are made of Lead Zirconium Titanate (PZT), which is known as high stability piezoelectric ceramic material.
Crystal Oscillator is difficult to manufacture while the ceramic resonator are easy to manufacture.
Applications ᾠCeramic resonators are used in microprocessor application where the frequency stability is not important while Crystal Oscillator can be found in everything from televisions to children’s toys that have electrical components.
Resonators are good for low-speed serial port communication while the crystal oscillators have frequencies available to support high-speed serial communications also.
The resonators do not have frequencies available for high-speed serial port communications.
In terms of clock based applications, Resonators are not very suitable for a Real-Time Clock/timekeeping/wall clock while oscillators may be suitable for timekeeping/RTC/wall clock if tuned with a variable capacitor, expect few minutes drift per year if not tuned.
tutorial/current-regulators-construction-working-and-design-types
Current Regulators: Construction, Working and Design Types
While Current regulators have been featured in several applications over the years they are arguably not one of the most popular topics in electronics design conversations until recently.
Current Regulators have now achieved a sort of ubiquitous status due to their important applications in LED Lighting among other applications.
Operation Principle of Current Regulator
with the major difference being the parameter they regulate and the quantity they vary to supply their output.
In voltage regulators, the current is varied to achieve the required voltage level, while current regulators usually involve variations in voltage/resistance to achieve the required current output.
As such, while it is possible, it is usually difficult to regulate voltage and current at the same time in a circuit.
To understand how Current regulators work requires a quick look at ohms law;
V=IR or I = V/R
or ensuring the Resistance and Voltage values are unchanged irrespective of the requirements/impacts of the connected load.
Current Regulator Working
To properly describe how a current regulator operates, let’s consider the circuit diagram below.
The variable resistor in the circuit above is used to represent the actions of a current regulator.
We will assume the variable resistor is automated and can auto-adjust its own resistance.
When the circuit is powered, the variable resistor adjusts its resistance to compensate for changes in the current due to variation in load resistance or voltage supply.
From basic electricity class, you should remember that when the load, which is essentially resistance (+ capacitance/inductance) is increased, an effective drop in current is experienced and vice versa.
Thus when the load in the circuit is increased (increase in resistance), rather than a current drop, the variable resistor reduces its own resistance to compensate for the increased resistance and ensure the same current flows.
In the same way, when the load resistance reduces, the variable resistance increases its own resistance to compensate for the reduction, thus maintaining the output current value.
Another approach in current regulation is to connect a sufficiently high resistor in parallel with the load such that, in line with the laws of basic electricity, current will flow through the path with least resistance which in this case will be through the load, with only a "negligible" amount of current flowing through the high-value resistor.
These variations also affect the voltage as some current regulators maintain current at the output by varying the voltage.
Thus, it’s almost impossible to regulate the voltage at the same output where the current is being regulated.
Current Regulators Design
Designing Current Regulators using Voltage Regulators
For the design of current regulators using IC-based voltage regulator, the technique usually involves setting up voltage regulators to have a constant load resistance and Linear voltage regulators are usually used because, the voltage between the output of linear regulators and their ground is usually tightly regulated, as such, a fixed resistor can be inserted between the terminals such that a fixed current flows to the load.
A good example of a design based on this was published in one of the EDN publications by Budge Ing In 2016.
but can be changed using an external resistive divider.
To ensure the optimal performance of the design, the voltage at the input terminal of the MAX1818 must be up to 2.5V and not above 5.5v as this is the operating range stipulated by the datasheet.
To satisfy that condition, choose a ROUT value that allows 2.5V to 5.5V between IN and GND.
For example when a load of say 100Ω with a 5V VCC, the device functions properly with ROUT above 60Ω as the value allows a maximum programmable current of 1.5V/60Ω = 25mA.
The voltage across the device then equals the minimum allowed: 5V - (25mA × 100Ω) = 2.5V.
as the temperature of the IC tends to get hot when loads with high current requirements are connected.
, consider the circuit below;
LM317s are designed in such a way that the regulator keeps adjusting its voltage until the voltage between it's output pin and its adjustment pin is at 1.25v and as such a divider is usually used when implementing in a voltage regulator situation.
But for our use case as a current regulator, it actually makes things super easy for us because, since the voltage is constant, all we need to do to make the current constant is to simply insert a resistor in series between the Vout and ADJ pin as shown in the circuit above.
As such, we are able to set the output current to a fixed value which is given by;
I = 1.25/R
With the value of R being the determinant factor of the output current value.
alongside another resistor to create a divider to the adjustable pin as shown in the image below.
to vary the resistance.
The voltage across R is giving by;
V = (1 + R1/R2) x 1.25
This means the Current across R is given by;
IR = (1.25/R) x (1+ R1/R2).
This gives the circuit a current range of I = 1.25/R and (1.25/R) x (1 + R1/R2)
Depend on the set current; ensure the watt rating of resistor R can withstand the amount of current that will flow through it.
Advantages and Disadvantages of using LDO as Current Regulator
for selecting the linear voltage regulator approach.
Regulator ICs incorporate over temperature protection which could come in handy when Loads with excessive current requirements are connected.
Regulator ICs have a greater tolerance for large input voltages and to a great extent support high power dissipation.
The regulator ICs approach involves the use of a smaller amount of components with the addition of only a few resistors in most cases except for cases where higher currents are required and power transistors are connected.
This means you could use the same IC for voltage and current regulation.
The reduction in the number of components could mean a reduction in implementation cost and design time.
from the regulator to the load in addition to the regulated output voltage.
This introduces an error which may not be permissible in certain applications.
This could, however, be reduced by choosing a regulator with a very low quiescent current.
Another downside to the regulator IC approach is the lack of flexibility in the design.
Design of current regulator using these parts are the most flexible as they are usually easy to integrate into existing circuits.
Current Regulator using Transistors
For the one with Transistors, consider the circuit below.
The shunt, which is essentially a low-value resistor, is used to measure the current flowing through the load.
When the circuit is switched on, a voltage drop is noted across the shunt.
The higher the value of the load resistance RL the higher the voltage drop across the shunt.
The voltage drop across the shunt act as a trigger for the control transistor such that the higher the voltage drop across the shunt, the more the transistor conducts and regulates the bias voltage applied to the base of the power transistor to increase or reduce conduction with the resistor R1 acting as the bias resistor.
Just like with the other circuits, a variable resistor can be added in parallel to the shunt resistor to vary the current level by varying the amount of voltage applied at the base of the control transistor.
Current Regulator using Op-Amp
For the second design path, consider the circuit below;
and just like in the example with the transistor, it also makes use of a shunt resistor for current sensing.
The voltage drop across the shunt is fed into the operational amplifier which then compares it to a reference voltage set by the Zener diode ZD1.
The op-amp compensates for any discrepancies (high or low) in the two input voltages by adjusting its output voltage.
The output voltage of the operational amplifier is connected to a high power FET and conduction occurs based on the applied voltage.
The major difference between this design and the first one is the reference voltage implemented by the Zener diode.
Both of these designs are linear and high amount of heat will be generated at high loads as such, heat sinks should be coupled to them to dissipate the heat.
The major advantage of this design approach is the flexibility it provides the designer.
The parts can be selected and the design configured to taste without any of the limitations associated with internal circuitry which characterizes the regulator IC based approach.
On the other hand, this approach tends to be more tedious, time-consuming, requires more parts, bulky, susceptible to failing, and more expensive when compared with the regulator based IC approach.
Application of Current Regulators
, to LED drivers and other applications where a fixed current needs to be regulated irrespective of the applied Load.
That’s it for this article! Hope you learned one thing or two.
Till Next time!
tutorial/current-mirror-circuit-wilson-and-widlar-current-mirroring-techniques
Current Mirror Circuit: Wilson and Widlar Current Mirroring Techniques
or using an amplifier circuit, the output is not perfect, as well as it has certain limitations and dependencies on the external things.
So to get a stable output, additional techniques are used in current mirror circuits.
Improving the Basic Current Mirror Circuit
There are several options to improve the output of Current Mirror Circuit.
In one of the solution one or two transistors are added over the traditional two transistors design.
Construction of those circuits uses emitter follower configuration to overcome the base current mismatch of the transistors.
The design can have a different kind of circuit structure to balance the output impedance.
as part of a large circuit.
It is the difference between input and output currents.
It is a tough task to minimize the difference as the difference of differential single-ended output conversion with the differential amplifier gain is responsible to control the rejection ratio of common mode and power supply.
or the output conductance.
It is crucial because it affects the stage again during the current source is acting like an active load.
It also affects the common mode gain in different situations.
coming from the power rail connection located across the input and output terminals.
Wilson Current Mirror Circuit
that accept the current across its input and provide the exact copy or mirrored copy of the current to its output.
In above Wilson Current Mirror Circuit, there are three active components which are BJTs and a single resistor R1.
Two assumptions are made here ᾠone is that all transistors have the same current gain which isand second is that collector currents of T1 and T2 is equal, as the T1 and T2 are matched and the same transistor.
Therefore
IC1 = IC2 = IC
And this applies for the base current too,
IB1 = IB2 = IB
The base current of the T3 transistor can easily be calculated by the current gain, which is
IB3 = IC3 / β ‐)
And the emitter current of the T3 will be
IB3 = ((β + 1)/ β) IC3 ‐)
If we look at the above schematic, the current across the T3 emitter is the sum of T2’s collector current and base currents of T1 & T2.
Therefore,
IE3 = IC2 + IB1 + IB2
Now, as discussed above, this can be further evaluated as
IE3 = IC + IB + IB
IE3 = IC + 2IB
Hence,
IE3 = (1+(2/β)) IC
can be changed as per the (2)
((β+1)/ β)) IC3 = (1+(2/β)) IC
The collector current can be written as,
IC = ((1+ β) / (β + 2)) IC3 ‐)
Again as per the schematic the current through
The output current can also be easily calculated if the base-emitter voltage of the transistors is less than 1V.
IC3 ⇠IR1 = (V1 ᾠVBE2 ᾠVBE3) / R1
need to be in proper values.
To make the circuit act as a constant current source, the R1 need to be replaced with a constant current source.
and also stabilize the voltage differences between the T1 and T2.
Advantages and Limitation of Wilson Current Mirror Technique
In case of basic current mirror circuit, the base current mismatch is a common problem.
However, this Wilson current mirror circuit virtually eliminates the base current balance error.
Due to this, the output current is near to accurate as of the input current.
Not only this, the circuit employs very high output impedance due to the negative feedback across the T1 from the base of the T3.
The improved Wilson current mirror circuit is made using 4 transistor versions so it is useful for the operation at high currents.
The Wilson current mirror circuit provides low impedance at the input.
It doesn't require additional bias voltage and minimum resources are needed to construct it.
When the Wilson current mirror circuit is biased with maximum high frequency the negative feedback loop cause instability in frequency response.
It has a higher compliance voltage compared with the basic two transistor current mirror circuit.
Wilson current mirror circuit creates noise across the output.
This is due to the feedback which raises output impedance and directly affect the collector current.
The collector current fluctuation contributes noises across the output.
Practical Example of Wilson Current Mirror Circuit
Here the Wilson current mirror is simulated using Proteus.
The three active components (BJT) are used to make the circuitry.
The BJTs are all 2N2222, with same specifications.
The pot is selected to change the current across Q2 collector which will further reflect on the Q3 collector.
For the output load, a 10 Ohms resistor is being selected.
Here is the simulation video for Wilson Current Mirror Technique-
In the video, the programmed voltage across Q2’s collector is reflecting across the Q3 collector.
Widlar Current Mirror Technique
, invented by Bob Widlar.
But there is a modification in the output transistor.
The output transistor uses an emitter degeneration resistor to provide low currents across the output using only moderate resistor values.
One of the popular application examples of Widlar current source is in the uA741 operational amplifier circuit.
In the below image, a Widlar current source circuit is shown.
The circuit consists of only two transistors T1 & T2 and two resistors R1 & R2.
The circuit is same as the two transistors current mirror circuit without the R2.
The R2 is connected in series with the T2 emitter and ground.
This emitter resistor effectively reduces the current across the T2 compared with the T1.
This is done by the voltage drop across this resistor, this voltage drop reduces the base-emitter voltage of the output transistor which further results in reduced collector current across the T2.
Analyzing and deriving Output Impedance for Widlar Current Mirror Circuit
As previously mentioned that the current across T2 is reduced in comparison with T1 current, that can be further tested and analyzed using Cadence Pspice simulations.
Let’s see the Widlar circuit construction and simulations in the below image,
The circuit is constructed in Cadence Pspice.
Two transistors with the same specification are used in the circuitry, which is 2N2222.
The current probes are showing the current plot across Q2 and Q1 collector.
In the above figure, the red plot, which is the collector current of Q1 is reducing while compared with Q2.
) across the base-emitter junction of the circuit,
VBE1 = VBE2 + IE2R2
VBE1 = VBE2 + (β+1)IB2R2
is for the output transistor.
It is completely different from the Input transistor as the current plot on the simulation graph clearly shows that the current in two transistors are different.
Therefore,
is
Vx / Ix
across the left ground to the R2, it is-
Again, applying Kirchhoff’s voltage law across the R2 ground to the ground of Input current,
VX = IX (R0 + R2) + Ib (R2 ᾠβR0)
article/introduction-to-swarm-robotics
Introduction to Swarm Robotics
Interacting, understanding and then responding to the situation are some of the greatest features of humans and those are the things which make us what we are.
We are born to live in a social society and we have always known about us that we are the most well-mannered social creature known since the creation of this planet.
The social culture and interaction with each other to help for a common goal is not only found in humans but also in other species of this planet like a flock of birds or fishes or bee's, all they have a one thing in common that they are having a collective behavior.
When the birds migrate its often seen they are in a group which is led by the lead member of their group and all are following them and their group are designed in a particular geometrical shapes despite being the birds have no sense of the shapes and figures and also the group is made such that the senior members of the group are on the boundaries while the young ones or the newborns are in the center.
The same characteristics are found in fire ants, these ants are a bit different from other species of the ants and are especially known for their group behavior, they build together, they eat together and they defend their colonies from the preys together, basically they know they can achieve more when they are in a group.
A recent study was being conducted on the group behavior of these ants in which it was found that they were capable of making strong structures whenever needed, such as when needed to create a small bridge to crossover.
Robots as a part of a Swarm
giving robustness and flexibility to the group.
Organizations and group emerge from the interactions between the individuals and between individuals and the enclosing environment, these interactions are scattered throughout the colony and so the colony can solve tasks that are difficult to solve by a sole individual which means working towards a common goal.
How Swarm Robotics is inspired from Social Insects
Multi-robotic systems maintain some of the characteristics of social insect like robustness, the robot swarm can work even if some of the individuals fail, or there are disruptions in the surrounding environment; flexibility, the swarm are able to create different solutions for different tasks and are able to change each robot role depending on the need of moment.
Scalability, the robot swarm is able to work in different group sizes, from a few individuals to thousands of them.
Characteristics of Robot Swarm
As said simple robotic swarm acquires a characteristic of social insects which are listed as follows
1. The swarm of robots must be autonomous, and able to sense and act in real environment.
2. The number of robots in a swarm must be large enough so as to back their every single task as a group which they are required to perform.
3. There should be homogeneity in the swarm, there can be different groups in the swarm but they should not be too many.
4. A single robot of the swarm must be incapable and inefficient with respect to their main objective, that is, they need to collaborate in order to succeed and improve the performance.
5. All the robots are necessitated to have only local sensing and communication capabilities with neighboring partner of the swarm, this ensures the coordination of the swarm is distributed and scalability becomes one of the properties of the system.
Multi-Robotics Systems and Swarm Robotics
Swarm robotics is a part of the multi-robotic system and as a group, they have some characteristics to their multiple axes that define their group behavior
: Collective size is the SIZE-INF which is N>>1 which is opposite to the SIZE-LIM, where the number of robot’s N is smaller than their respective environment size they are put in.
: Communication range is COM-NEAR, so that the robots can only communicate with the robots which are close enough.
: Communication topology for the robots in the swarm would be generally TOP-GRAPH, robots are linked in a general graph topology.
: Communication bandwidth is BAND-MOTION, Communication cost between the two robots is the same as moving the robots between locations.
: Collective reconfigurability is generally ARR-COMM, this is coordinated arrangement with the members that communicate, but it also could be ARR-DYN, that is the dynamic arrangement, positions can change randomly.
: Process ability is PROC-TME, where the computational model is a tuning machine equivalent.
: Collective composition is CMP-HOM, meaning that robots are homogeneous.
Advantages of Multi-Robotics Systems as compared to a Single Robot
Task Parallelism: We all know the tasks could be decomposable, and we all are aware of the agile development method, so by using parallelism, groups can make to perform the task more efficiently.
Task Enablement: A group is more powerful than a single one and the same applies for the swarm robotics, where a group of robots can make task do certain task that is impossible for a single robot
Distribution in Sensing: As the swarm has a collective sensing so it has wider range of sensing than the range of a single robot.
Distribution in Action: A group of robots can actuate different actions at different places at the same time.
Fault Tolerance: The failure of a single robot within a swarm of robots within a group does not imply that the task is going to fail or cannot be accomplished.
Experimental Platforms in Swarm Robotics
There are different experimental platforms used for swarm robotics which involves the use of the different experimental platforms and different robotic simulators to stimulate the environment of swarm robotics without the actual hardware needed.
Different robotic platforms are used in different swarm-robotic experiments in different laboratories
it has various sensors to help the bot out which includes range sensors and camera.
It uses wheels for moving from one to another.
It's developed by Rice University, USA
SwarmBot is a swarm robotic platform developed for research by Rice University.
It can autonomously work for approximate of 3 hours of a single charge, also these bots are self-enabled to find and dock themselves to charging stations placed on walls.
It involves the use of the distance sensor, vision sensors and compass.
It uses wheels for their motion
It's developed in the KOVAN Research Lab at Middle East Technical University, Turkey.
Kobot is specifically designed for the research in swarm robotics.
It is made of several sensors that make it a perfect platform for performing various swarm robotic situations such as coordinated motion.
It has can work autonomously for 10 hours on a single charge.
It also includes a replaceable battery which is to be recharged manually and It is mostly been used in the implementation of self-organizing scenarios.
It makes the use of various sensor to get the things to work like sensors for light, IR, position, force, speed, temp, humidity, acceleration, and a mic.
It makes the use of treels attached to its base for its movements.
It's developed by the école Polytechnique Fédérale de Lausanne (EPFL), Switzerland.
S-bot is one of the several competent and substantial swarm robotic platforms ever built.
it has a unique gripper design capable of gripping objects and other s-bots.
Also, they can approximately work out for 1 hour on a single charge.
It makes use of distance and light sensors.
It's developed by the University of Stuttgart, Germany.
It makes its movement on the wheels.
Jasmine mobile robots is a swarm robotic platforms which is used in many swarm robotic research.
It uses a variety of sensors like distance, camera, bearing, acceleration, and a mic.
école Polytechnique Fédérale de Lausanne (EPFL), Switzerland
It's based on the wheel motion.
E-puck is primarily designed for educational purposes and is one of the most successful robots.
However, due to its simplicity, it is often employed in swarm robotics research as well.
It has user replaceable batteries with a working time of 2-4 hours.
It uses a combination of distance and light sensors.
Harvard University, USA
It uses vibrations of the system for the movement of the system's body.
Kilobot is a moderately recent swarm robotic platform with a unique function of group charging and group programming.
Due to its simplicity and low power consumption, it has an uptime of up to 24 hours.
Robots are charged manually in groups in a special charging station.
Robotic simulators solve the problem of the hardware needed for the job of testing the credibility of the bots in the artificially simulated real environment parameters.
There exist many robotic simulators which can be used for multi-robotic experiments, and more specifically for the swarm robotic experiments and all of them differ in their technical aspects but also in the license and the cost.
Some of the simulators for the swarm bots and Multi-robotic platforms are as follows:
SwarmBot3D: SwarmBot3D is a simulator for the multi-robotics but designed specifically for the S-Bot robot of the SwarmBot project.
Microsoft Robotics Studio: The robotic studio is a simulator developed by Microsoft.
It allows multi-robotic simulation and requires the Windows platform to run.
Webots: Webots is a realistic mobile simulator that allows multi-robot simulations, with already built models of the real robots.
It can simulate real collisions by applying the physics of the real world.
However, its performance decreases when working with more than robots making simulations with a large number of robots difficult.
Player/stage/Gazebo: Player/stage/Gazebo is an open source simulator with multi-robotic capabilities and a wide set of available robots and sensors ready for use.
It can well handle the simulations of the swarm-robotic experiments in a 2D environment with very good results.
The population size in the environment can scale up to 1000 simple robots in a real time.
Algorithms and Technique used for various tasks in Swarm Robotics
Here we are going to explore the various techniques used in swarm robotics for various simple tasks such as aggregation, dispersion etc.
These tasks are the basic initial steps for all the high end working in swarm robotics.
Aggregation is getting all the bots together and it’s really important and initial step in other complex steps such as pattern formation, self-assembly, exchange information and collective movements.
A robot uses its sensors such as proximity sensors and microphone which uses sound exchange mechanisms with the help of the actuator such as speakers.
The sensors helps a single bot to find the nearest robot which also turns out to be the center of the group, where the bot has to concentrate solely on the other bot which is at the center of the group and reach towards it and the same process is followed by all the members of the swarm which let them aggregate all.
When the robots are aggregated at a single place then the next step is to disperse them in the environment where they work as a single constitute member of the swarm and this also helps in the exploration of the environment each bot of the swarm work out as a single sensor when it is left to explore.
Various algorithms have been proposed and used for the dispersion of the robots, one of the approaches includes the potential field algorithm for the dispersion of the robots in which the robots get repel by the obstacles and other robots which allow the swarm environment to disperse linearly.
One of the other approaches involves dispersion based on reading the wireless intensity signals, wireless intensity signals allows the robots to disperse without the knowledge of their nearest neighbors they just catch the wireless intensities and arrange them in order to disperse them in the surrounding environment.
Formation of patterns in swarm robotics is a major characteristic of their collective behavior, these patterns can be very much helping when a problem is to be solved which involves the whole group works together.
In pattern formation, bots create a global shape by changing the portion of the individual robots where each bot has just local information.
A swarm of robots forms a structure with an internal and external defined shape.
The rules that make the particle/robots to aggregate in the desired formation are local, but a global shape emerges, without having any global information with respect to an individual member of the swarm.
The algorithm uses virtual springs between the neighboring particles, taking into consideration how many neighbors they have.
What's the meaning of a team if they all can't work out the problem together and that's the best part of a swarm? Collective movement is a way of letting to coordinate a group of robots and making them move together as a group in a cohesive way.
It’s a basic way of making some collective tasks done and can be classified into two types formation and flocking.
There are many methods of collective movement but only those allowing scalability with a growing number of robots are of concern where each robot recognizes the relative position of its neighbor and react with respective forces which could be attractive or repulsive to form structures for collective movements.
Task Allocation is a problematical area in swarm robotics on the basis of labor division.
However, there are various methods used for the labor division, one of them is that each robot would keep an observation on other robot’s tasks and maintains the history for the same and later then can change its own behavior to get fit itself in the task, this method is based on gossip communication and surely it has its pros of better performance but at the same time it has a con that due to limited robustness and packet loss during communication it comes out to be less scalable.
In the other method, tasks are announced by some of the robots and a certain number of other robots attend them simultaneously, it's a simple and reactive method.
Swarm robotics is very much successful in the task of the source searching, especially when the source for the searching is complex as in case of sound or odor.
The searching by the swarm robotics is done in two ways one is global other is local, and the difference between the two is the communication.
One with the global communication among the robots in which the robots are able to find the global maximum source.
The other one is restricted to only local communication between the robots to find the local maxima.
The ants have collective transportation of objects where an individual ant waits for the other mate for the cooperation if the object to be transported is too heavy.
Under the same light robots, the swarm makes the things work out in the same way where each robot has the advantage of getting cooperation from the other robots for transporting the objects.
S-bots offers a great platform for solving the problem of transportation where they self-assemble to cooperate and their algorithm scales up if the object to be transported to be is heavy.
The other method is the collective transportation of objects where the objects are collected and stored for later transportation, here the robots have two different tasks - collecting the objects and placing them in a cart, and collectively move the cart carrying those objects.
Collective mapping is used for the exploration and mapping of the big indoor areas using a large number of robots.
In one method the mapping is carried out by the two group of two robots, which exchange information to merge the maps.
The other method is role based in which the robot can assume any of the two roles which are moving or landmark that they can exchange for the movement of the swarm.
Also, the robots have a certain estimate of their position so have to an estimate of the location of the other robots so as to build a collective map.
The Real World Application of Swarm Robotics
Though the extensive research on swarm robotics has begun around 2012 till now it has not come out with the commercial real-world application, it is being used for medical purposes but not at that large scale and still is under testing.
There are various reasons behind that this technology is not coming out commercially.
The collective behavior of the swarm comes out from the individual which requires to design a single robot and its behavior, and presently there exist no method of going from the individual to group behavior.
Extensive requirements for the laboratories and infrastructure for further development.
The various basic tasks performed in swarm robotics suggest out that these are non-linear and so building out the mathematical models for their working is quite hard
Besides these challenges, there are further security challenges for the individual and the swarm due to their simple design
Physical capture of the robots.
Identity of the individual in the swarm, that the robot must know if it is interacting with a robot of its swarm or another swarm.
Communication attacks on the individual and the swarm.
The main goal of the swarm robotics is to cover a wide region where the robots could disperse and perform their respective tasks.
They are useful for detecting hazardous events like leakages, landmines etc and the main advantage of a distributed and moveable network of sensors is that it can sense the wide area and even act on it.
The applications of the swarm robotics are really promising but there is still a need for its development both in algorithmic and modeling part.
interview/sameer-rajan-co-founder-cto-faebikes-on-how-his-company-setting-up-ev-charging-infrastructure-in-bangalore
Sameer Ranjan ᾠCo-Founder and CTO of FAEbikes on how his company is setting up the EV Infrastructure for India with over 200 charging stations in Bangalore
allowing them to remotely monitor their bikes.
The users who wish to avail their services can simply download their mobile application, book their ride and unlock the bike remotely via the app to start using it.
These bikes can easily reach 55kmph speed with a range of 70Km providing an economical ride through the city.
Recently in 2018 the company also started working on charging stations and has announced to set-up India’s biggest network of charging station in Bangalore.
Inspired by its works and plans, CircuitDigest approached Sameer with few questions and his response is as follows‐
When me and Yugraj moved to Bangalore for our work, we realized the need for a better transport solution.
I used to travel from RT Nagar to Koramangala for office and had to change three buses.
The commute used to take more than 1.5 hours.
We realized that there is a huge gap between the cheap buses and autos and taxis which are very expensive.
So we came up with FAE Bikes which was very close to the pricing of buses and more than 3 times cheaper than autos and taxis.
At the same time, it provided the independence and convenience of a personal vehicle which no other transport solution provided.
We started with a vision to provide clean, shared and sustainable mobility for the masses.
But during the course of our journey, we became a part of the bigger EV ecosystem.
We realized that mass EV adoption cannot happen without setting up the infrastructure.
And hence, in October 2018, we launched FAE Spark, a network of EV Charging Stations.
Today, setting up charging stations is not sustainable, but we have come up with a business model for FAE Spark which leverages our unique position and allows us to be sustainable from the beginning.
As more and more of India is migrating to cities, sustainable solutions are needed in every domain to survive with our limited resources.
We believe the future of mobility is going to be shared and electric.
Personal Vehicles sit idle for 95% of the time.
A shared mobility solution will help in better utilization of available resources, reduce congestion and EVs are going to be the drivers of this.
EVs are necessary in reducing the operational costs to get better and sustainable unit economics.
From the start, we have been a technology-focused company.
We are continuously working on improving our service and making it more accessible to user with the help of technology.
We are installing IoT solution in all our scooters which make our scooters smart and keyless.
Our users can lock and unlock the scooters using the app.
They can also lock and unlock the storage space using our IoT solution to access the helmet.
Along with this, an array of features like remote engine immobilization, geo-fencing, tow detection, crash detection etc help us effectively run the service.
This allows us to deploy our vehicles on a pick-anywhere-drop-anywhere model which is necessary for a true micro-mobility solution.
We have developed the IoT solution in-house and it has helped us save more than 75% cost per unit.
We are manufacturing it in Karnataka and sourcing the components from across India.
EV ecosystem in India is growing fast but it’s still in a very nascent stage.
However, there is a lot of resistance to EV acceptance in India.
The two biggest challenges the EV ecosystem is facing today are ᾠlack of awareness and lack of infrastructure.
Few years back, due to government subsidies, a lot of Low-speed, Low-power Electric scooters with Lead-Acid batteries were sold.
This gave everyone the wrong impression about electric scooters.
The general public is of the opinion that electric scooters are going to be sluggish and lack acceleration.
They can’t drive if two people are sitting and won’t be able to go on a flyover.
However, this is far from reality about today’s scooters.
The vehicles above today can beat even Activa in the initial acceleration.
They can take lead at signals and also have decent top speeds.
These scooters have enough power for a zippy ride even on flyovers carrying two riders.
Along with this, the ride is very quiet and smooth.
There are no vibrations like an IC vehicle.
It is the responsibility of the whole EV ecosystem, especially OEMs, to spread this awareness to the public so that more and more people start choosing EVs over IC vehicles.
During the course of building Fae Bikes, we have become entrenched in the ecosystem.
We are tackling both the problems from the front lines.
We are creating awareness about the vehicles by bringing them directly to the public.
At the same time, we are also focused on creating the charging infrastructure so that people can purchase EVs without range anxiety.
Yes, we are proud to say that we are setting up India’s biggest network of charging stations.
We aim to install atleast 1000 charging stations this year.
We have developed the charging station in-house after a lot of R&D effort.
We have ensured that the charging stations are equipped with a lot of safety features.
However, the journey for setting up these charging stations has just started.
We have currently installed 10 charging stations for a start.
We are in the process of streamlining our manufacturing.
Also, We have recently finalized our partnership with 200 petrol bunks across Bangalore and we will soon begin the process of installation in the petrol bunks.
Our charging stations will also be compatible with all available EVs.
A lot of effort has gone towards developing fast charging for 4-wheelers around the world.
Consequently, a lot of standards already exist for fast charging cars like CHAdeMO etc.
However, similar efforts are lacking for smaller vehicles like scooters.
We wanted to make fast charging solutions for scooters as India is a two-wheeler majority country.
We launched our proprietary fast charging solution in October 2018, with which we are able to charge 1% per minute.
I can’t reveal technical details at this stage on how this was achieved.
However, I would like to share an exciting development happening in our labs.
We have prototyped a solution which will give a boost of 8-11 kilometers to a scooter with a charge of less than 1 minute.
I believe this will revolutionize how we view public charging and range anxiety.
The biggest hurdle currently is lack of a charging standard.
This is necessary to bring down the CAPEX of setting up charging stations.
I feel that it is the ideal time for the Government to create standards before the market grows further.
As more and more manufacturers enter the fray, it will become difficult to enforce a single standard.
Battery Swapping is an excellent way to increase the range of EVs.
It has seen a lot of success around the world.
Take the example of Gogoro which has set up swapping stations in Taiwan, Paris etc.
A few companies in India are also trying to set up battery swapping station with Sun mobility being the biggest name.
However, battery swapping comes with its own set of challenges and benefits.
I will start with the benefits.
Only battery swapping can replicate the time it takes up to fill petrol.
The battery is under completely controlled environment and can be charged slowly which increases battery life.
If proper diagnostics and Battery life management are implemented, the batteries can be used beyond their normal life i.e.
even at lesser capacities like 75%.
However, the capital expense associated with battery swapping is too high.
Also, battery technology Is certain to evolve quickly and all the batteries taken by the swapping station owner will become obsolete quickly.
Also standardization of battery across vehicles is necessary if a non-OEM wants to scale the battery swapping stations.
Lithium cell manufacturing in India is non-existent.
Today, All battery OEMs are importing Lithium cells from China to develop battery packs.
The reason for this is that India simply doesn’t have the technology and manufacturing ability to manufacture lithium cells.
India is one of the largest importers of lithium-ion cells and batteries.
It is also true that many times, these battery packs are better than the Chinese battery packs.
However, concrete steps have already been taken by few agencies and even government has signed MoUs for setting up manufacturing of Lithium-ion Cells.
As India is lacking in critical resources to make the cells including lithium, I think recycling these materials from discarded batteries is going to be the future.
We aim to become the India’s largest e-fleet aggregator and network of charging stations.
We aim to be in the forefront of EV revolution in India by building cutting edge tech innovations for India.
We stand successful in creating a sustainable business model by leveraging EV sharing and infrastructure that enables accelerate EV transformation.
We look forward to scale this model across the world and spearhead the transformation.
tutorial/current-mirror-circuit
Current Mirror Circuit (Part 1): Introduction, Characteristics and Construction
Characteristic and Dependency of Current Mirror Circuit
A current mirror circuit has lots of primary and secondary dependencies and that is the main concern to characterize current mirror circuit.
A proper current mirror circuit can be characterized using three specifications.
A current mirror circuit, mirror or copy the input current of one active device to the other active devices output.
An ideal current mirror circuit is an ideal current amplifier with the inverting configuration that can reverse the current direction.
Therefore, for an ideal current amplifier, the current transfer ratio is an important parameter.
Thus, AC output resistance plays a major role in the stability of output current with respect to voltage changes.
A minimum voltage is required to keep the transistor in active mode, so the minimum voltage depends on the transistor specifications.
Limitations in Real Current Mirror Circuits
The ideal circuit and the real circuit, these two are completely different.
In the real world, there is nothing called perfect or ideal.
However, before understanding the limitations of current mirror circuits with respect of real-world applications, one needs to understand the voltage and current source and their ideal and actual behaviors.
Therefore, we can connect any load resistance across the ideal voltage source and get a stable and fixed voltage every time.
This is not the case in real-world voltage source.
In the real world, voltage sources like batteries, power supplies etc could not provide unlimited or infinite current to the loads.
Same as like the ideal voltage source, irrespective of the terminal voltage the current source can deliver or accept currents.
But in the real world, the voltage also affects the constant current delivery process.
But in a real scenario they have noises, tolerance, ripples thus the output voltage varies.
This all affects the current mirror output.
Current Mirror circuit using BJT
using the transistor.
This is done by providing a voltage across the base-emitter junction of the BJT and the collector current is taken as an output.
In this voltage to current converter configuration, simple negative feedback across the transistor converts the voltage to current converter properties to an opposite logarithmic current to voltage converter.
Generally, the negative feedback is done by joining the base and the collector of the transistor.
Before understanding how the circuit works it is essential to understand the transistor operating characteristics.
In the active mode operation, the transistor collector current can be calculated by multiplying the base current with the ratio of β.
The ratio between emitter current and collector current is called ɑ.
The relation between these two can be described using simple mathematical formation
ɑ = β/(β+1)
In the previous image, a forward biased diode is used in parallel of the base-emitter junction which is providing constant voltage to the transistor.
The voltage across the base-emitter is constant depending on the current flowing through the diode.
However, the diode current can be controlled by the bias resistor.
If the current through the diode is decreased by increasing the value of the bias resistance, the voltage drop across the diode will also reduce.
By the effect of reduced base-emitter junction voltage, the emitter current will also decrease in the same proportion.
One thing needs to be remembered that the ɑ and β of the transistor are constant.
This diode can be easily changed using a transistor which is same as the other counterpart.
, two transistors are shown which are used to create the current mirroring circuit.
Transistor T1 and T2 need to be the same counterpart.
Also, the two transistors should be placed close to each other for equal heat transfer.
is flowing.
As per the Kirchhoff's law, the current at the T1 collector is ᾍ
IREF = IC + IB1 + IB2
Therefore, when both transistors work with zero base-collector bias, the base currents are equal,
Base current of T1 (IB1) = Base current of T2 (IB2) = Total Base current of the node (IB)
can be calculated using the below formula-
ROUT = VA + VCE / IC As per the R =V / I
and the current mirror behavior still works in the lowest output voltage, can be calculated like this:
is the scale current.
Current Mirror Technique using MOSFET
The working of the MOSFET current mirror circuit is similar as described in the previous transistor section.
For the case of MOSFET M2, it will also remain in saturation mode as long as the output voltage is greater than the saturation voltage.
Therefore the input current across the M1 will control directly the output current of M2.
MOSFET device function like this, the drain current reflects the function of the gate to source and drain to gate voltage.
So, the formula can be written using the below function,
ID = f (VGS, VDG)
Due to this, the input current in the MOSFET M1, is mirrored to the drain current.
In the image, the input current is provided by the bias resistor.
is 0 for the MOSFET M1, the drain current of M1 will be
ID = f (VGS, VDG=0)
The same gate to source voltage is reflected across the M2.
So, if the M2 biased using zero
share identical properties and exact matching, then the
is true.
):
The function can be expressed as
Also, the output resistance can also be calculated as the output resistance is finite,
is a transistor technology related constant, W/L is the ratio of Width and Length and λ is used for the modulation constant of channel length.
are gate to source voltage, threshold voltage and drain to source voltage respectively.
= 0 and the output MOSFET resistance is still high, current mirror behaviour still works in the lowest output voltage.
The compliance voltage can be calculated by deriving the condition ᾍ
VCV = VGS (ID at VDG = 0)
Or, f-1 (ID) when the VDG = 0
Practical Model for Current Mirror Circuit
The current mirror circuit is simulated using Proteus models.
In the left side, the current mirror circuit using 2N2222 BJT is shown where two identical transistor pair is used.
Instead of the programming resistor, a potentiometer is used to control the current flow in the live simulation.
This same thing is created for the 2N6660 MOSFETs.
An amp meter is connected on both input and output current side.
As the simulation goes, the input current is almost same and reflecting across the secondary side.
The in detail working can be seen in the Video given below.
Applications of Current Mirror Circuit
from a single source.
Hence, changing one reference point also change the current source across different parts of the circuit.
article/what-is-lidar-and-how-does-lidar-works
What is LiDAR and How does it Work
What is LiDAR?
) is a ranging technology that measures the distance of an object by firing beams of light at the object and use the time and wavelength of the reflected beam of light to estimate the distance and in some applications (Laser Imaging), create a 3D representation of the Object.
While the idea behind laser can be traced to the work of EH Synge in 1930, It wasn’t a thing until the early 1960s, after the invention of laser.
Essentially a combination of laser-focused imaging with the ability to calculate distances using the time of flight technique, it found its earliest applications in Meteorology, where it was used to measure clouds, and in Space, where a laser altimeter was used for mapping the moon’s surface during the Apollo 15 mission.
Since then, the technology has improved and has been used in diverse applications including; detection of seismic activities, oceanography, archeology and navigation to mention a few.
How Does LiDAR Work
(Laser).
to image objects and its, as such, able to detect all kind of material compositions, including; non-metals, rocks, rain, chemical compounds, aerosols, clouds and even single molecules.
LIDAR systems could fire up to 1,000,000 light pulses per seconds and use the time taken for the pulses to be reflected back to the scanner to determine the distance at which objects and surfaces around the scanner are located.
The technique used for the distance determination is known as time of flight and it’s equation is given below.
Distance = (Speed of Light x Time of Flight) / 2
In most applications, other than just distant measuring, a 3D map of the environment/object at which the light beam was fired is created.
This is done via continuous firing of the laser beam at the object or environment.
as the light waves are diffused back through the direction where they came.
Depending on the application, LIDAR systems use different variations of backscattering including Rayleigh and Raman scattering,
Components of a LIDAR System
A LIDAR system typically comprises of 5 elements which are expected to be present irrespective of variations due to application.
These main components include:
Laser
Scanners and Optics system
Processor
Accurate timing electronics
Inertial Measurement Unit and GPS
The Laser serves as the source of the energy for the light pulses.
The wavelength of the laser deployed in LIDAR systems differ from one application to another due to the specific requirements of certain applications.
For instance, Airborne LiDAR systems use 1064 nm diode pumped YAG lasers whilst Bathymetric systems use 532nm double diode pumped YAG lasers which penetrate water (up to 40 meters) with much less attenuation than the airborne 1064nm version.
However, Irrespective of the applications, the lasers used are usually of low energy to ensure safety.
Scanners are an important part of any LIDAR system.
They are in charge of projecting laser pulses to surfaces and receiving back the reflected pulses from the surface.
The speed at which images are developed by a LIDAR system is dependent on the speed at which the scanners capture the backscattered beams.
Irrespective of the application, the optics used in a LIDAR system must be of high precision and quality to obtain the best results especially for mapping.
The type of lenses, specific glass choice, along with the optical coatings used are major determinants of the resolution and range capabilities of the LIDAR.
Depending on the application, a variety of scanning methods can be deployed for different resolutions.
Azimuth and elevation scanning, and dual axis scanning are some of the most popular scanning method.
A high capacity processor is usually at the heart of any LIDAR system.
It is used to synchronize and coordinate the activities of all the individual components of the LIDAR system ensuring all components are working when they should.
The processor integrates the data from the scanner, the timer (if not built into the processing subsystem), the GPS and the IMU to produce the LIDAR point data.
These elevation point data are then used to create maps depending on the application.
In Driverless Cars, the point data are used to provide a real-time map of the environment to help the cars with obstacle avoidance and general navigation.
With light travelling at a speed of about 0.3metres per nanoseconds and thousands of beams usually reflected back to the scanner, the processor is usually required to be of high speed with high processing capabilities.
Thus, the advancements in the processing power of computing elements has been one of the major drivers of LIDAR technology.
Accurate timing is of the essence in LIDAR systems as the entire operation is built on time.
The timing electronics represents the LIDAR subsystem that records the exact time a laser pulse leaves and the exact time it returns to the scanner.
It’s precision and accuracy cannot be over emphasized.
Due to the scattered reflection, pulses sent out usually have multiple returns each of which needs to be precisely timed to ensure the accuracy of the data.
When a LiDAR sensor is mounted on a mobile platform such as satellites, airplanes or automobiles, it is necessary to determine the absolute position and the orientation of the sensor to retain useable data.
This is achieved by the use of an Inertial measurement system (IMU) and Global Positioning System (GPS).
The IMU usually comprises of an accelerometer, gyroscope, and a magnetometer to measure the velocity, orientation, and gravitational forces, which combined together, are used to determine the angular orientation (Pitch, roll and Yaw) of the scanner relative to the ground.
The GPS on the other hand provide accurate geographical information regarding the position of the sensor, thus allowing for direct georeferencing of the object points.
These two components provide the method for translating sensor data into static points for use in a variety of systems.
The extra information obtained using the GPS and IMU is crucial to the integrity of data acquired, and it help ensures distance to surfaces are correctly estimated, especially in mobile LIDAR applications like Autonomous vehicles and Air Plane based imagine systems.
Types of LiDAR
While LIDAR systems can be classified into types based on quite a number of factors, there are three generic types of LIDAR Systems which are;
Range finder LIDAR
Differential absorption LIDAR
Doppler LIDAR
These are the simplest kind of LIDAR systems.
They are used to determine the distance from the LIDAR scanner to an object or surface.
By using the time of flight principle described under the “how it worksᾠsection, the time taken for the reflection beam to hit the scanner is used to determine the distance between the LIDAR system and the object.
Differential absorption LIDAR systems (sometimes referred to as DIAL), is usually used in the investigating the presence of certain molecules or materials.
DIAL systems usually fire laser beams of two wavelengths which are selected in such a way that one of the wavelengths will be absorbed by the molecule of interest whilst the other wavelength will not be.
The absorption of one of the beams results in a difference (differential absorption) in the intensity of the return beams received by the scanner.
This difference is then used to deduce the level of presence of the molecule being investigated.
DIAL has been used to measure chemical concentrations (such as ozone, water vapor, pollutants) in the atmosphere.
Doppler LiDAR is used to measure the velocity of a target.
When light beams fired from the LIDAR hits a target moving towards or away from the LIDAR, the wavelength of the light reflected/scattered off the target will be changed slightly.
This is known as a Doppler shift - as a result, Doppler LiDAR.
If the target is moving away from the LiDAR, the return light will have a longer wavelength (sometimes referred to as a red shift), if moving towards the LiDAR the return light will be at a shorter wavelength (blue shifted).
Some of the other classifications on which LIDAR systems are grouped into types include:
Platform
Type of Backscattering
Types of LiDARbased on Platform
Using platform as a criteria, LIDAR systems can be grouped into four types including;
Ground-based LIDAR
Airborne LIDAR
Spaceborne LIDAR
Motion LIDAR
These LIDARs differ in construction, materials, wavelength, outlook and other factors which are usually selected to suit what works in the environment for which they are to be deployed.
Types of LIDAR Based on Type of Backscattering
During my description of how LIDAR systems work, I mentioned that reflection in LIDAR is via backscattering.
Different type of backscattering exits and its sometimes use to describe the type of LIDAR.
Types of backscattering include;
Mie
Rayleigh
Raman
Fluorescence
Applications of LiDAR
Due to its extreme accuracy and flexibility LIDAR has a wide number of applications, in particular, the production of high-resolution maps.
As well as surveying, LIDAR has been used in agriculture, archaeology, and in robots as it’s currently one of the major enablers of the autonomous vehicle race, being the major sensor used in most vehicles with the LIDAR system performing a role similar to that of the eyes for the vehicles.
There are 100s of other applications of LiDAR and will try to mention as many as possible below.
Autonomous Vehicles
3D Imaging
Land Survey
Power Line Inspection
Tourism and Parks Management
Environmental Assessment for Forest protection
Flood Modeling
Ecological & Land Classification
Pollution Modeling
Oil and Gas Exploration
Meteorology
Oceanography
All sort of military Applications
Cell Network Planning
Astronomy
LiDAR Limitations
For example, in Foggy conditions, a significant amount of false signals are generated due to beams being reflected by the fog.
This usually leads to the mie scattering effect and as such, a bulk of the fired beam doesn’t return back to the scanner.
A similar occurrence is experienced with rain as rain particles cause spurious returns.
in the middle of the road if they sensed what they believed to be another car or a pedestrian.
Advantages and Disadvantages of LiDAR
To wrap up this article, we probably should look at reasons why you LIDAR could be a good fit for your project and reasons why you probably should avoid it.
1. High Speed and accurate data acquisition
2. High Penetration
3. Not affected by the intensity of light in its environment and can be used at night or in the sun.
4. High Resolution Imaging compared to other methods.
5. No Geometrical Distortions
6. Easily integrates with other data acquisition methods.
7. LIDAR has minimum human dependence which is good in certain applications where human error could affect the reliability of data.
1. The cost of LIDAR makes it overkill for certain projects.
LIDAR is best described as relatively expensive.
2. LIDAR systems perform poorly in heavy rain, fog or snow conditions.
3. LIDAR systems generate large datasets which require high computational resources to process.
4. Unreliable in turbulent water applications.
5. Depending on the wavelength adopted, the performance of LIDAR systems is limited altitude as the pulses fired in certain kind of LIDARs become ineffective at certain altitudes.
LIDAR for Hobbyist and Makers
Due to the cost of LIDARs, most of the LIDAR systems in the market (like the velodyne LIDARs) are used in industrial applications (to bring together all “non-hobbyistᾠapplications).
The closest to “hobbyist gradeᾠLIDAR system available right now are the iLidar Solid-State LiDAR sensors designed by Hybo.
It is a small LiDAR system capable of 3D mapping (without rotating the sensor) with an effective maximum range of 6 meters.
The sensor is equipped with a USB port alongside a UART/SPI/i2C port through which communication can be established between the sensor and a microcontroller.
iLidar was designed to suit everyone and the features associated with LiDAR makes it attractive to makers.
article/future-of-lithium-ion-battery-pack-manufacturers-in-asia
Future is Supercharged for Lithium-Ion Battery Pack Manufacturers in Asia
jumped from US$ 115 billion to US$ 127 billion during 2018-2019, and the market revenues are expected to escalate 3x in the next decade.
The world is moving from the traditional energy sources and solar cells and lithium-ion batteries are becoming indispensable for a wide range of end-user industries, such as automotive and consumer electronics.
Manufacturers are adopting efficient, transparent, and flexible manufacturing processes to improve productivity and speed up the time to market.
Reducing production costs with advent of next-generation manufacturing technologies is likely to remain the primary focus for market players in the coming years.
and battery electric vehicles (BEVs).
However, the Asia Pacific region is giving the lithium-ion battery industry a second wind with favourable governmental policies and profitable sales opportunities in developing Asian countries, such as China and India.
The Asia Pacific region (excluding Japan) holds over one-third share of the global market for lithium-ion battery packs and will maintain its position as the fastest-growing market in the upcoming years.
Increasing needs for efficient energy storage systems in a wide range of industrial sectors and burgeoning adoption of EVs in the region will remain the important factors to trigger the market growth.
Leading battery manufacturers across the world are jumping on the bandwagon after the sales of BEVs reached new heights in the Asia Pacific region.
The rapidly-growing lithium mining activities in Australia are attracting investors to feed to need for lithium in the ever-expanding lithium-ion battery pack market.
Developing countries in the region, including China and India, are the linchpin of Asia’s lithium-ion battery pack market.
Being one of the world’s largest automotive markets, China and India are home to the world’s leading battery manufacturers as well as new entrants in the market.
Global automakers, such as Suzuki Motor Corporation (SMC) and DENSO Corporation, are investing heavily in the developing markets for lithium-ion battery packs, and it is likely to generate a powerful incentive in the upcoming years.
The commanding lead of developing countries in the global lithium-ion battery pack market will only widen with the wave of planned new manufacturing facilities in China and India.
China’s Lead in Lithium-Ion Battery Industry: Reading between the Lines
China is reaching the threshold of a new EV era with its aggressive efforts in boosting e-mobility in the country.
With its strict EV policies and the burgeoning number of EVs on the road, China is becoming a success penetrating market for lithium-ion battery pack manufacturers.
Leading stakeholders in China’s lithium-ion battery pack market, including manufacturers and investors, are adopting new business strategies to capitalize on the surging domestic as well as global demand.
Taking into consideration the country’s interest in strengthening domestic industries for the future growth of battery-powered EVs, Chinese manufacturers are scaling up the manufacturing of lithium-ion batteries enormously.
In June 2018, BYD Co Ltd.
ᾠa Chinese manufacturer of rechargeable batteries and battery-powered vehicles ᾠannounced that it has opened a new, 24GWh battery factory in Western China's lithium-rich province ᾠQinghai.
The company also announced that it is planning to expand the total production capacity of this facility to 60GWh by 2020.
As the Chinese lithium-ion battery packs market is heavily dependent on lithium imports, the country is increasing its focus on developing the domestic resources to satisfy its burgeoning demand for lithium-ion batteries in the coming future.
China is eyeing lithium reserves in Australia and South America, becoming one of the biggest global consumers of lithium.
While its focus remains on expanding its domestic lithium output, China is jostling across the lithium-ion battery packs market with significant investments in lithium deals, which is helping the country to tighten its grip on raw material supplies.
Recent developments in the energy storage market in China indicate manufacturersᾠefforts to develop and strengthen a business model with its supply chain that concentrates significantly in a single country.
By isolating the access to raw materials and establishing strict technical standards, China will soon take a position to set prices of lithium-ion batteries with its aggressive geopolitical influence in the market.
Despite the continual efforts made by the United States to fortify its dominance in the lithium-ion battery pack market, China is expected to hold the lead in the market over the next decade.
A New Lease of Life for Lithium-Ion Battery Pack Manufacturers in India
With China as the frontrunner in the manufacturing of BEVs, the lithium-ion battery pack market in the Asia Pacific region has witnessed a quantum leap in the EV era.
Meanwhile, India has emerged as a highly lucrative market for lithium-ion battery manufacturers, as the Indian lithium-ion battery pack market valued nearly US$ 8.5 billion in 2018.
The country is stepping towards a high-tech e-mobility ecosystem through the medium of changing governmental policies, which is creating profitable opportunities for lithium-ion battery manufacturers in India.
In order to cash in on the EV wave in the country, leading lithium-ion battery pack manufacturers in India are adopting strategies to manufacture batteries locally.
A burgeoning number of automakers are investing heavily in India’s EV market and Indian battery manufacturers are gearing up to strengthen their local battery manufacturing ecosystem to meet the future surge in demand for EV batteries.
A majority of manufacturers are working closely with research organizations in the country for technology transfer, bolstering research & development activities the Indian market for lithium-ion battery packs.
In June 2018, Munoth Industries Limited (MIL) ᾠa manufacturing company based in Chennai, India ᾠannounced that it has invested over US$ 115 million (Rs 799 crores) to set up India’s maiden lithium-ion cell manufacturing unit in the southern state of Andhra Pradesh.
The company announced its collaboration with Council for Scientific & Industrial Research (CSIR), which is a Government of India undertaking, and China’s Better Power Company Limited to produce custom size 3.7V pouch lithium-ion cells based on OEM requirements in India.
Amara Raja Batteries Ltd.
ᾠanother leading lithium-ion battery manufacturer in India, also announced in September 2018 that it is building a lithium-ion battery assembly plant in Andhra Pradesh.
The company also declared its collaboration with the Indian Institute of Technology in Chennai and that it aims to supply lithium-ion batteries for e-rickshaws—small privately-owned three-wheeler taxis.
The company currently imports lithium-ion cells from LG Chem Ltd., a Korean chemical company, and it aims to end its dependence on foreign imports with its plans to kickstart its own manufacturing unit in the country.
In June 2018, Exide Industries Ltd.
ᾠa storage battery producing company in India ᾠannounced that it has signed a joint venture with Leclanché SA ᾠa Swiss battery manufacturer ᾠto manufacture lithium-ion battery packs in India.
The company also announced that Leclanché will license its technology and its lithium-ion battery manufacturing plant will be based in Gujarat.
The company also declared that it will concentrate on providing batteries for electric buses and e-rickshaws.
Multi-million Dollar Government Incentives will Fuel Lithium-ion Battery Production in India
FAME India Phase II is expected to ramp up the EV sales in the country, in turn, providing an impetus to the demand for lithium-ion battery packs.
The Indian government’s thrust on e-mobility will boost sales of electric passenger cars, e-buses, and e-rickshaws in the country, which will create a lucrative growth environment for lithium-ion battery pack manufacturers in India.
Some of the other examples of the government initiatives that are shaping the future of India’s lithium-ion battery pack market include,
An announcement from the Government of India indicates a potential collaboration between LIBCOIN and Bharat Heavy Electricals Limited (BHEL) to form a consortium for the establishment of a 1GWh lithium-ion battery plant in India, which will be scaled up to 30GWh during the course of the project.
A Memorandum of Agreement was signed between Central Electrochemical Research Institute (CECRI) ᾠa national laboratory under CSIR ᾠand RAASI Solar Power Pvt Ltd ᾠa solar power company ᾠfor transfer of technology for RAASI’s lithium-ion battery manufacturing plant in Tamil Nadu.
In June 2018, Indian Space Research Organisation (ISRO)’s Vikram Sarabhai Space Centre (VSSC) issued a Request for Qualification (RFQ) to transfer its lithium-ion cell manufacturing technology.
VSSC aims to commercialize this technology in India’s lithium-ion battery pack market and help lithium-ion battery manufacturers in India to bring down the manufacturing cost to bolster local production of lithium-ion battery packs.
As the world is awakening to the positive business potential in the lithium-ion battery pack market, the competition will only become more intense with time.
Manufacturers in the Asia Pacific region will need to slash their production costs and introduce lithium-ion battery packs with innovative and high-tech features to gain an edge.
Achieving operational excellence by the virtue of cutting-edge technologies is expected to emerge as a popular trend in Asia’s lithium-ion battery pack market in the foreseeable future.
tutorial/different-types-of-transformers-and-their-applications
Different Types of Transformers and Their Applications
Transformer Types based on Voltage Level
This center tapped condition can also be seen on the secondary side.
For the Isolation transformer, the voltage level is the same for both sides.
1. Step-Down Transformer
step down transformers are used in electrical distribution system which works on very high voltage to ensure low loss and cost-effective solution for long distance power delivery requirements.
To convert the high voltage to a low voltage supply line, Step down transformer is used.
2. Step-Up Transformer
That means the number turns in secondary winding is higher than the primary winding.
etc where low voltage is converted to a much higher voltage.
High voltage is required for power distribution related application.
Step up transformer is used in the grid to step up the voltage level before the distribution.
3. Isolation Transformer
That means the number of turns in primary and secondary winding is same in isolation transformer.
from primary to secondary or vice-versa.
Transformer Types based on Core material
The transformer transfers the energy by conducting electromagnetic flux through a core material.
Different core materials produce different flux density.
Depending on the core materials, several types of transformers are used in the power and electronics domain.
1. Iron Core Transformer
Iron core transformer uses multiple soft iron plates as the core material.
Due to the excellent magnetic properties of iron, the flux linkage of the iron core transformer is very high.
Thus, the efficiency of the iron core transformer is also high.
The soft iron core plates can be available in multiple shapes and sizes.
The coils of the primary and secondary wound or wrapped on a coil former.
After that, the coil former is mounted in soft iron core plates.
Depending on the core size and shapes, a different type of core plates is available in the market.
Few common shapes are E, I, U, L, etc.
The iron plates are thin, and multiple plates are bunched together to form the actual core.
For example, E type cores are made with thin plates with a look of letter E.
Iron core transformers are widely used and usually heavier in weight and shape.
2. Ferrite Core Transformer
A ferrite core transformer uses a ferrite core due to high magnetic permeability.
This type of transformer offers very low losses in the high-frequency application.
Due to this, ferrite core transformers are used in high-frequency application such as in switch mode power supply (SMPS), RF related applications, etc.
Ferrite core transformers also offer a different type of shapes, sizes depending on the application requirement.
It is mainly used in electronics rather than electrical application.
The most common shape in the ferrite core transformer is E core.
3. Toroidal Core Transformer
Toroidal core transformer uses toroid shaped core material, such as iron core or ferrite core.
Toroids are ring or donut shaped core material and widely used for superior electrical performance.
Due to the ring shape, the leakage inductance is very low and offers very high inductance and Q factors.
The windings are relatively short and weight is much less than traditional, same rating transformers.
4. Air Core transformer
Air Core transformer does not use any physical magnetic core as the core material.
The flux linkage of the air-core transformer is made entirely using the air.
which produces an electromagnetic field around it.
When a secondary coil is placed inside the magnetic field, as per the Faraday law of induction, the secondary coil is induced with a magnetic field which further is used to power the load.
However, air core transformer produces low mutual inductance compared to physical core material such as iron or ferrite core.
It is used in portable electronics as well as Radiofrequency related applications.
Due to the absence of physical core material, it is very light in terms of weight.
Properly tuned air core transformer also used in wireless charging solutions, where the primary windings are constructed inside the charger and the secondary windings are situated inside the targeted device.
Transformer Types based on Winding Arrangement
The transformer can be classified using winding orders.
One of the popular types is Auto Winding Transformers.
Till now, the primary and secondary winding is fixed but in case of an auto-winding transformer, the primary and the secondary coil can be connected in series and the center tapped node is movable.
Depending on the center tapped position, the secondary voltage can be varied.
The auto is not the short form of Automatic; rather it is to notify the self or single coil.
This coil forms a ratio which consists of two parts, primary and secondary.
The position of the center tap node determines the primary and secondary ratio thus varying the output voltage.
, an instrument to produce variable AC from a steady AC input.
It is also used in Power transmission and distribution related applications where the high voltage lines are needed to be changed frequently.
Types of Transformersbased on Usage
There are several types of transformers also available which works in a specific domain.
Both electronics and electrical sectors, several dedicated transformers are used as a step-down or step-up transformer based on the application of application.
So, the transformers can be classified as below based on usage:
1. Power Domain
Power Transformer
Measurement Transformer
Distribution Transformer
2. Electronics Domain
Pulse Transformer
Audio Output Transformer
1. Transformers used in Power domain
In Electrical, the Power domain deals with the power generation, measurement, and distribution.
However, it is a very large field where transformers are an essential part to accommodate safe power conversion and successful power delivery to the substation and to the end users.
The transformers which are used in the power domain can be both outdoor and indoor but mostly outdoor.
The rating can be more than 30KVA to the 500-700KVA or in some cases that can be equal to or more than 7000KVA for small rated power transformer.
The medium rated power transformer can be up to 50-100 MVA whereas large rated power transformers are capable to handle more than 100MVA.
The most common power transformers are filled with oils.
This is required to minimize the power loss in the power distribution system.
, but in some cases, Single phase small power transformers are also used.
Three Phase Power transformers are the most costly and efficient than the single phase power transformers.
Measurement transformer is often referred to as an instrument transformer.
This is another commonly used measurement instrument in the power domain.
A measurement transformer is used to isolate the main power and convert the current and voltage in a smaller ratio to its secondary output.
By measuring the output, the Phase, Current and Voltage of the actual power line can be measured.
The above image is showing the construction of the current transformer.
This is used in the last phase of the power distribution system.
Distribution transformers are step down transformer, which converts High grid voltage to the end customer required voltage, 110V or 230V.
It can also be single phase or three phases.
Distribution transformers can be smaller in shape as well as bigger, depending on the conversion capacity or ratings.
Distribution transformers can be further categorized into based on the type of insulation it uses.
It can be a dry type or can be liquid-immersed.
It is made using laminated steel plates mostly constructed in C shape as a core material.
Distribution transformer also has a different type of classification based on the location it is used.
The transformer can be mounted on a utility pole, if so, it is called a pole mounted distribution transformers.
It can be placed inside of an underground chamber, mounted on a concrete pad (pad mounted distribution transformer) or inside an enclosed steel box.
Generally, distribution transformers have a rating of less than 200kVA.
2. The transformer used in Electronics domain
In electronics, various small miniature transformers are used which can be PCB mounted or can be fixed inside the small product enclosure.
Pulse transformers are one of most used PCB mounted transformers that produce electrical pulses in a constant amplitude.
It is used in various digital circuits where pulse generation is needed in an isolated environment.
Therefore, the pulse transformers isolate the primary and secondary and distribute primary pulses to the secondary circuit, often digital logic gates or drivers.
Properly constructed pulse transformers should need proper galvanic isolation as well as small leakage and stray capacitance.
is another commonly used transformer in the electronics domain.
It is specially used in Audio related application where impedance matching is required.
Audio transformer balances the amplifier circuit and loads, typically a loudspeaker.
The audio transformer can have multiple primary and secondary coils, separated or center tapped.
So we have covered various kinds of transformer, other than that there are some other special purpose transformer but they are out of scope of this article.
article/introduction-to-lora-and-lorawan-what-is-lora-and-how-does-it-work
Introduction to LoRa and LoRaWAN: What is LoRa and How Does It Work?
The ability of a thing to communicate with other “thingsᾠ(a device cloud/server)is what gives the “thingᾠthe right to attach the “internetᾠto its name.
While tons of communication protocols exist, each of them lacks one thing or the other which made them “not totally suitableᾠfor IoT applications.
The Major problems being power consumption, range/coverage and bandwidth.
comes in.
and they worked as expected.
Features of LoRa
A LoRa radio comprise of a few features which helpit achieve long-range effective power and Low cost.
Some of these features include;
Modulation Technique
Frequency
Adaptive Data Rates
Adaptive PowerLevels
Lora radios use the chirp spread spectrum modulation technique to achieve a significantly high communication range while maintaining low power characteristics that are similar to theFSK modulation physical layer based radios.
While chirp spread spectrum modulation has been around for a while with applications in military and space communications, LoRa presents the first, low-cost commercial application of the modulation technique.
While the LoRa technology is frequency agnostic, Communication between LoRa radios happen via the use of unlicensed sub-GHz radio frequency bands that are available around the world.
These frequencies vary from region to region and often also differ between countries.
For instance the 868MHz is commonly used for LoRa communications in Europe, while the 915MHz is used in North America.
Irrespective of the frequency, LoRa can be used without any major variation in the technology.
Frequency Bands for LoRa in Different Countries
Using Lower frequencies than those of the communication modules like WiFi based on the 2.4 or 5.8GHz ISM bands enable a muchlarger coverage area especially for NLOS situations.
It is important to note that permissions are still required in some countries before the unlicensed bands can be used.
LoRa uses a combination of variable bandwidth and spreading factors (SF7-SF12) to adapt the data rate in a trade-off with the range of the transmission.
Higher spreading factor allows longer range at the expense of lower data rate, and vice versa.
The combination of bandwidth and spreading factor can be chosen according to the link conditions and the level of data to be transmitted.
Thus, a higher spreading factor improves transmission performance and sensitivity for a given bandwidth, but it also increases transmission time as a result of lower data rates.
These can vary from as few as 18bps up to 40Kbp
The power level used by LoRa radios is adaptive.
It is dependent on factors like the data rate and link conditions among others.
When a fast transmission is required, the transmitted power is pushed closer to the maximum and vice versa.
Thus,battery life is maximized and network capacity maintained.
Power consumption also depends on the class of devices among several other factors.
LoRaWAN
It is a bi-directional protocol which takes full advantage of all the features of the LoRa technology to deliver services including reliable message delivery, end to end security, location and multicast capabilities.
The standard ensures the interoperability of the various LoRaWAN networks world-wide.
which is probably best solved by examining the OSI reference stack Model.
Thus LoRaWAN defines the communication protocol and system architecture for the network, while LoRa architecture enables the long-range communication link.
The two of them merged together to provide the functionality that determines battery life of a node, the network capacity, the quality of service, the security and other applications served by the network.
While LoRaWAN is the most popular MAC layer for LoRa other proprietary layers which are also built on the LoRa technology exists.
A good example is Symphony link by Link Labs which is specially developed for industrial applications.
The LoRaWAN Network Architecture
Opposed to the mesh network topology adopted by most networks, LoRaWAN uses the star network architecture, thus, rather than have each end-device in an almost always on state, repeating transmission from other devices to increase range, end-devices in the LoRaWAN network communicate directly with gateways and are only on when they need to communicate with the gateway since range is not a problem.
This is a contributing factor to the Low power features and High battery life obtained in the LoRa end devices
The LoRa Network Architecture comprises of four major parts;
1. End Devices
2. Gateways
3. Network server
4. Application Server
1. End Devices
These are sensors or actuators at the network edge.
End-devices serve different applications and have different requirements.
In order to optimize a variety of end application profiles, LoRaWAN utilizes three different device classes to which end-devices can be configured as.
The classes feature trade offs between downlink communication latency and battery life of the device.
The three major classes are;
1. Bi-Directional end-devices (Class A)
2. Bi-directional end-devices with scheduled receive slots (Class B)
3. Bi-directional end-devices with maximal receive slots (Class C)
r immediately after an Uplink.
For example, they are devices that need to receive message delivery confirmation from the server after an uplink.
For this class of devices, they must wait till an Uplink is sent to the server before any downlink can be received.
As a result of this, communication is kept at the minimum and they thus have the lowest power operation and the highest battery life.
A good example of class A devices is a LoRa based Smart Energy Meter
in addition to the downlink received when an uplink is sent (Class A + a scheduled extra downlink).
The scheduled nature of this downlink ensures the operation is still low power since communication is only active at scheduled intervals but the extra power consumed during the scheduled downlink increases the power consumption beyond that of the Class A devices, as such, they have a lower battery life compared to class A end-devices.
They are designed to be nearly always open to communications from the server.
They consume more power than the other classes and have the lowest battery life.
Good examples of class C devices are end devices used in fleet management or real traffic monitoring.
2. Gateways
Gateways (also referred to as concentrators) are devices connected to the network server via standard IP connections that relay messages between the central network server backend and end-devices using single-hop wireless communication protocol.
They are designed to support bi-directional communication and are equipped with multicast enabling the software to send mass distribution messages like over-the-air updates.
At the heart of every LoRa gateway is a multi-channel LoRa demodulator able to decode all LoRa modulation variants on several frequencies in parallel.
For a large-scale network operator, the key distinguishing factors should be the radio performance (sensitivity, sending power), the connection of the SX1301 chip to the gateway MCU (USB to SPI or SPI to SPI) and the support and distribution of PPS signal whose availability allows for precise time synchronization over the entire gateway population in a network
LoRa spreads communication between end-devices and gateways across multiple frequency channels and data rates.
The spread spectrum technology uses data rates ranging from 0.3 kbps to 50 kbps to prevent communications from interfering with each other and creates a set of "virtual" channels that increase the capacity of the gateway.
To maximize both the battery life of the end-devices and the overall network capacity, the LoRa network server manages the data rate and RF output for each end-device individually through an adaptive data rate (ADR) scheme.
3. Network Server
Lora Network server is the interface between the Application server and the Gateways.
It relays commands from the Application server to the gateway while ferrying data from the gateways to the application server.
It perform functions including ensuring there are no duplicate packets, Scheduling acknowledgements and managing the data rate and RF output for each end-device individually using a adaptive data rate (ADR) scheme.
4. Application Server
The application server determines what the data from the end devices are used for.
Data Visualization etc are probably done here.
LoRaWAN Security and Privacy
The importance of security and privacy in any IoT solution cannot be over emphasized.
The LoRaWAN protocol specifies encryption to assure your data is secure, concretely
* Per-device AES128 keys
* Instant regeneration/revocation of device keys
* Per-packet payload encryption for data privacy
* Protection against replay attacks
* Protection against man-in-the-middle attacks
both of which provide split, encrypted communication for network management and application communication.
The network session key, shared between the device and the network is responsible for authentication of the end node data while the application session key, shared between the application and the end node is responsible for guaranteeing the privacy of the device data.
Key Features of LoRAWAN
* >160 dB link budget
* +20 dBm TX power
* Exceptional IIP3
* 10dB selectivity improvement over FSK
* Tolerant to in-channel burst interference
* Lowest RX current - 10mA
* Lowest sleep current
* Ultrafast wake-up (sleep to RX/TX)
Advantages of LoRa
Below are some of the advantages associated with LoRa;
With up to 15km LOS Range, its range can’t be compared with that of any other Communication protocol.
LoRa offers hyper low power radios which makes them Ideal for devices that are required last for 10 years or more on a single battery charge.
Infrastructures for LoRaWAN are extremely low cost compared to other networks and cost of radios for end-devices are equally Low.
More so, several open source versions of infrastructures like gateways are being developed which helps to further reduce costs.
Thousands of end devices could be connected to a single LoRa gateway
Disadvantages of LoRa
when compared with most of the other technology which makes it not ideal for certain applications where high data rates are required.
Applications of LoRa
The applications of LoRa are only Limited by imagination.
It has been one of the major drivers of smart city in countries around the world with full-scale city wide LoRa Network already deployed in several cities.
Applications of LoRaWAN cuts across all sorts of IoT Solution.
A few are listed in the image below.
Semtech recently announced the launch of new products which will reduce current power consumption level by 50% and they also indicated exploring partnerships with Imprint energy which makes ultra thin flexible batteries.
With the ultra thin imprint batteries, which could practically fit in anything, powering device with a communication range of over 13Km, I believe the goals of a fully connected world would have been achieved.
tutorial/op-amp-integrator-circuit-working-construction-applications
Operational Amplifier Integrator Circuit: Construction, Working and Applications
which is a very useful circuit in analog related application.
produces an output voltage across the op-amp, which is directly proportional to the integral of the input voltage; therefore the output is dependent on the input voltage over a period of time.
Construction and Working of Op-amp Integrator Circuit
.
A simple Op-amp configuration consists of two resistors, which creates a feedback path.
In the case of Integrator amplifier, the feedback resistor is changed with a capacitor.
Op-amp gain is Infinite, therefore the Inverting input of the amplifier is a virtual ground.
When a voltage is applied across the R1, the current start to flow through the resistor as the capacitor has very low resistance.
The capacitor is connected in the feedback position and the resistance of the capacitor is insignificant.
will be very low.
The capacitor begins to charge up by the input voltage and in the same ratio, the capacitor impedance also starts to increase.
The charging rate is determined by the RC - time constant of R1 and C1.
The op-amp virtual earth now hampered and the negative feedback will produce an output voltage across the op-amp to maintain the virtual earth condition across the input.
The Op-amp produce a ramp output till the capacitor gets fully charged.
The capacitor charges current decreases by the influence of the potential difference between the Virtual earth and the negative output.
Calculating the Output Voltage of Op-amp Integrator Circuit
The complete mechanism explained above can be described by using mathematical formation.
Let’s see the above image.
The iR1 is the current flowing through the resistor.
The G is the virtual ground.
The Ic1 is the current flowing through the capacitor.
iR1 = iinverting terminal + iC1
iR1 = iC1
The capacitor C1 has a voltage-current relationship.
The formula is ᾍ
IC = C (dVC /dt)
is ᾍ
(Vin - VG / R1), where VG is the voltage in virtual ground node
Now the is equal to
C (d(VC ᾠVout)/dt)
As the G node is a virtual ground point and the op-amp is an ideal op-amp, the voltage across this node is 0.
Therefore,
The basic Integrator circuit, which is shown previously, has a drawback.
The capacitor blocks the DC and due to this, the DC gain of the Op-Amp circuit become Infinite.
Therefore, any DC voltage at the Op-amp Input, saturates the Op-amp output.
To overcome this problem, resistance can be added in parallel with the capacitor.
The resistor limits the DC gain of the circuit.
The Op-Amp in Integrator configuration provides different output in a different type of changing input signal.
The output behavior of an Integrator amplifier is different in each case of Sine wave input, square wave input or triangular wave input.
Op-amp Integrator Behavior on Square Wave input
In square wave, voltage levels change from Low to High or high to low, which makes the capacitor gets charged or discharged.
During the positive peak of the square wave, the current start to flow through the resistor and in the next stage, the current flow through the capacitor.
Since the current flow through the op-amp is zero, the capacitor gets charged.
The reverse thing will happen during the negative peak of the square wave input.
For a high frequency, the capacitor gets very minimal time to fully charge up.
For perfect integration, the frequency or the periodic time of the input square wave needs to be less than the circuit time constant, which is referred as: T should be less than or equal to the CR (T <=CR).
can be used to produce square waves.
Op-amp Integrator Behavior on Sine Wave input
As discussed previously, that in low frequency or in DC, the capacitor produces a blocking current which eventually reduces the feedback and the output voltage saturates.
In such a case, a resistor is connected in parallel with capacitor.
This added resistor provides a feedback path.
The output sine wave is 90 degree out of phase.
The corner frequency of the circuit will be
Fc = 1 / 2πCR2
And the overall DC gain can be calculated using ᾍ
Gain = -R2 / R1
can be used to generate sine waves for integrator input.
Op-amp Integrator Behavior on Triangular Wave input
In triangular wave input, the op-amp again produces a sinusoidal wave.
As the amplifier act as a low pass filter, the high-frequency harmonics are greatly reduced.
The output sine wave only consists of low-frequency harmonics and the output will of low amplitude.
Applications of Op-amp Integrator
Integrator is an important part of the instrumentation and is used in Ramp generation.
In function generator, the integrator circuit is used to produce the triangular wave.
Integrator is used in wave shaping circuit such as a different kind of charge amplifier.
It is used in analog computers, where integration is needed to be done using the analog circuit.
Integrator circuit is also widely used in analog to the digital converter.
Different sensors also use an integrator to reproduce useful outputs.
article/how-hvdc-transmission-can-be-the-future-of-renewable-energy-generation
How HVDC Transmission can be the Future of Renewable Energy Generation
emerging as a feasible mechanism of energy management.
offer advantages in terms of lower emissions and cost-savings, when deployed overhead for long distances and underground or underwater for short distances.
By offering maximum transient efficiency and lower power losses, regardless of the distance that the electricity travels, HVDC transmission systems are creating a significant potential for power transmission over long distances, such as islands, and even continents.
Advancements in HVDC technologies are paving way for renewable electricity systems, signifying positive future prospects of the HVDC transmission system market, which was valued at nearly US$ 7.4 billion in 2018.
HVDC Transmission: An Electricity Superhighway to the New Era of Renewables
HVDC transmission systems are emerging as the bedrock upon which the new energy system based on renewable sources is being developed and implemented.
Renewable energy systems, such as solar and wind power projects, are often highly volatile and located in remote areas.
The ever-evolving HVDC technology is gaining ground in the new energy economy with long-haul HVDC transmission lines that can transport power with maximum efficiency and power minimal losses.
HVDC lines are becoming the “electricity superhighwaysᾬ which are expediting the future of renewable power generation systems in three ways—interconnecting existing power plants, developing new solar power stations, and integrating offshore wind energy projects.
Power semiconductors, high-voltage cables, and converters are among the key components of the HVDC technology, which bring distinct features to the modern direct current (DC) transmission system.
The needs for building new power stations can be deferred with the deployment of HVDC transmission systems, as it interconnects different power systems to operate more efficiently.
The new power system can attain greater economic and environmental gains coming from large hydroelectric resources, which replace thermal generation systems in traditional power systems through HVDC transmission lines.
HVDC transmission has become power superhighway for large-scale integration of renewable power resources to offer interconnected grids, which are reliable and flexible enough to address the challenges of the new renewable energy economy.
HVDC transmission grids enable load balancing between HVDC power superhighways and sharing of lines and converter stations in solar projects and offshore wind power stations.
Thereby, deployment of HVDC transmission systems is considered as an economically viable way of providing redundancy and reliability in such power networks.
In addition, HVDC transmission systems also offer feasible solutions to the existing right-of-way challenges.
One HVDC transmission system deployed overhead can prove to be more reliable than a double circuit AC transmission line.
An HVDC infrastructure can improve the electricity transient efficiency by using insulated HVDC cables in underground and subsea applications, which can accelerate the right-of-way permitting processes.
Moreover, HVDC transmission systems can also be installed adjacent to or on the existing AC lines, reducing the needs for right-of-way land use.
Voltage Supply Converters (VSC) Technology in HVDC Transmission Systems
HVDC transmission systems employ current-source, line-commuted converters (LCC), which require reactive power from series capacitors, shunt banks, or filters to operate.
However, a conventional HVDC transmission system fails to offer dynamic voltage support to the AC network and control the system voltage under an acceptable range, within the desired tolerance.
Consequently, voltage supply converters are used in conventional HVDC transmission systems, not only to provide dynamic voltage regulation to the AC network but also to control the power flow in the system.
HVDC transmission systems based on VSC technology can offer independent control of both active and reactive power with no commutation failures.
The switching of the IGBT valves in VSC-based HVDC transmission follows a pulse width modulation (PWM), which allows the system to adjust the phase angle and amplitude of converter AC output voltage with constant DC voltage.
In addition, VSC-based HVDC transmission systems consist of two independent control and protection systems, which comprise of digital signal processors and microcontrollers, and offer redundancy to ensure high reliability.
Such features are attributed to the end-usersᾠinclination towards VSC technology over the LCC technology in HVDC transmission systems.
VSC-based HVDC systems are growing in popularity in the HVDC transmission system market, with over 55% of the revenue share of the market.
VSC-based transmission technology has come of age for conventional HVDC transmission systems, despite being a relatively costlier option for higher rated transmission applications.
are boosting the adoption of VSC technology to enhance the reliability of HVDC transmission in renewable energy projects implemented worldwide.
For example, Toshiba Energy Systems & Solutions Corporation ᾠa leading Japanese manufacturer of power generation systems ᾠannounced the installation of a VSC-based HVDC transmission link connecting the Japanese mainland (Honshu) to the northern island of Hokkaido, in March 2019.
The company announced that this is Japan’s first VSC-based HVDC system that ensures 600 MW of interconnection capacity at all times.
In April 2019, the ABB Group ᾠa Swiss-Swedish multinational corporation operating in power, heavy electrical equipment, and automation technology segments ᾠannounced that it has established a joint venture with Hitachi, Ltd.
ᾠa Japanese multinational conglomerate companyᾠto deliver VSC-based HVSC transmission system for Higashi-Shimizu substation in Japan.
The company announced that the VSC-based HVDC transmission systems will include two VSC converters (300,000 kW each), and Hitachi will construct the system, which will comprise of Hitachi converter transformers and an ABB HVDC converter with a Control and Protection System.
Advancements in Ultra HVDC (UHVDC) Infrastructure Salient for Renewable Energy Transmission
The development of a UHVDC transmission system is one of the latest advancements in the HVDC transmission technology, which allows DC voltage transmission of at least 800kV; a conventional HVDC transmission system generally uses voltages between 100 kV to 600kV.
As the new global energy economy gradually moves towards the continental-scale power grids, UHVDC transmission systems are likely to gain immense importance across the world.
Developed regions are among the most favorable markets for UHVDC transmission systems, as developed countries are generating large amounts of renewable energy.
North America and Europe are among the largest markets for HVDC transmission systems, as governing bodies in these regions are investing heavily to develop HVDC infrastructures in order to meet their climate goals.
The United Kingdom is among the leading European countries to have implemented HVDC transmission systems.
The UK shares HVDC links with several neighboring countries, including Norway, Ireland, France, and Holland.
In addition, the United States has been boosting investments in clean energy generation, and the adoption of HVDC transmission is increasing at a rapid pace in the country.
The ever-expanding interstate network of electricity superhighway systems in the U.S.
makes North America the largest market for HVDC transmission system, with nearly one-fourth revenue share of the global market.
However, a mounting number of emerging economies have been showing promising growth in the renewable energy generation with the development of hydropower stations and wind power projects.
Developing nations are home to large-scale solar and wind energy projects, and UHVDC transmission systems are being adopted to meet the ever-growing power demand in these countries.
China became one of the leading countries in the world to first adopt a UHVDC transmission system.
In 2010, the world’s first UHVDC transmission line was built by the ABB Group between Shanghai and Xiangjiaba in China with a power rating of 6.4 GW and a total length of around 1,907 km.
By 2017, the country invested over 400 billion yuan (US$ 57 billion) to develop at least 21 new UHVDC transmission lines in the country.
General Electric Company (GE) ᾠan American multinational conglomerate –commissioned the first 1,500 MW phase of the two-phased HVDC power transmission system in Chhattisgarh, India, in 2017.
The Power Grid Corporation of India Limited ᾠan Indian state-owned electric utility company ᾠinvested over 6,300 crore INR in the project.
The Power Ministry announced that the project capacity was further upgraded to 6,000 MW with an investment of over 5,200 crore INR, in December 2018.
GE announced that this was the company’s first UHVDC project in India as well as in the world, which is a 1,287 km energy superhighway with the transmit power of up to 3,000 MW.
With the increasing adoption of UHVDC transmission systems in emerging economies, such as China and India, the Asia Pacific region (excluding Japan) is emerging as a high-growth market for HVDC transmission systems.
The future trends in the electricity transmission & distribution (T&D) sector are highly influenced by the mix of renewable power sources.
Increasing investments in the T&D sector will bolster renewable energy generation in the upcoming years.
This will consequently, trigger the global adoption of HVDC transmission systems as a flexible and economical solution for managing new energy generation challenges and integrating renewable sources in the upcoming years.
article/how-to-measure-current-in-a-circuit-with-different-current-sensing-techniques
Current Sensing Techniques using Different Current Sensors
Hall Effect Sensor Current Sensing Method
Hall Effect sensor produces an output voltage depending on the magnetic field.
The ratio of the output voltage is proportional to the magnetic field.
During the current sensing process, the current is measured by measuring the magnetic field.
The output voltage is very low and needs to be amplified to a useful value by using a high gain amplifier with very low noise.
Apart from amplifier circuit Hall Effect sensor requires additional circuitry as it is a linear transducer.
Can be used in higher frequency.
Can be used in both AC and DC accurately.
Noncontact based method.
Can be used in a rough environment.
It is reliable.
The sensor drifts and requires compensation.
Additional circuit requires for useful output.
Costly than shunt based technique.
can sense current from several mili-amps to thousands of amperes.
Due to this, Smart Grid Monitoring Application also uses a different type of Hall effect sensor to monitor the conductor current.
Flux Gate Sensor Current Sensing Method
The inductor core which is used for the fluxgate sensor works in the saturation region.
The saturation level of this inductor is highly sensitive and any internal or external flux density changes the saturation level of the inductor.
The permeability of the core is directly proportional to the saturation level, hence the inductance also changes.
This change in inductor value is analyzed by the flux gate sensor to sense the current.
If the current is high, the inductance become lower, if the current is low, the inductance become high.
In the above image, the basic construction of a flux gate sensor is shown.
There are two coils primary and secondary wrapped around a saturable inductor core.
The changes in the current flow can alter the core permeability resulting in the change of inductance across the other coil.
Can measure in a wide range of frequency.
Has great accuracy.
Low offset and drifts.
High secondary power consumption
A risk factor increases for voltage or current noise in the primary conductor.
Only suitable for DC or low-frequency AC.
measurement, overcurrent detection etc.
Rogowski Coil Current Sensing Method
Rogowski coil is named after German physicist Walter Rogowski.
The Rogowski coil is made using a helical shape air core coil and wrapped around the targeted conductor for current measurement.
In the above image, the Rogowski coil is shown with additional circuitry.
The Additional circuitry is an integrator circuit.
Rogowski coil provides output voltage depending on the rate of current change in the conductor.
An additional integrator circuit is required for making an output voltage which is proportional to the current.
It is a good method to detect fast high-frequency current change.
Safe operation in terms of handling the secondary winding.
Low-Cost solution.
Flexibility in handling due to open loop construction.
Temperature compensation is not complex.
Only suitable for AC
Has low sensitivity than the current transformer.
Rogowski coil provides flexible measuring option.
As Rogowski coil response is very fast over transients or high-frequency sinusoidal waves, it is a good choice to measure high-frequency current transients in the power lines.
In power distribution or in smart grid, Rogowski coil provides excellent flexibility for current measurements.
Current Transformer Current Sensing Method
Current transformer or CT is used to sense the current by secondary voltage which is proportional with the current in secondary coil.
It is Industrial transformer that converts the large value of voltage or current into a much smaller value in its secondary coil.
The measurement is taken across the secondary output.
here.
Large current handling capacity, more than the other methods shown in this article.
Do not require additional circuitry.
Requires maintenance.
Hysteresis occurs due to magnetization.
High primary current saturates the ferrite core materials.
Shunt Resistor Current Sensing Method
When the current flow through a low-value resistor, it produces a voltage difference across the resistor.
Let's take an example.
The wattage of the resistor is a critical factor to be considered.
However, there are very small value resistors also available in the market, where the resistance is in mili-ohms range.
In such a case, the voltage difference across the resistor is also very small.
A high gain amplifier is required to increase the amplitude of the voltage and finally, the current is measured using the reverse calculation basis.
Since the copper trace of a PCB offer very small resistance, one can use the trace to measure the current.
However, in such an alternative approach, several dependencies are also a huge concern to get an accurate result.
The main game-changing factor is temperature drifting.
Depending on the temperature, the trace resistance gets changed resulting in an error result.
One needs to compensate for this error in the application.
Very cost effective solution
Can work in AC and DC.
Additional equipment not required.
Not suitable for higher current operation due to heat dissipation.
Shunt measurement provides an unnecessary decrease in system efficiency due to the energy wastage across the resistor.
Thermal drift provides error result in a high-temperature application.
The application of Shunt resistor includes digital amp meter.
This is an accurate and cheaper method other than the Hall Effect sensor.
The shunt resistor can also provide a low resistance path and allows an electric current to pass one point to the other point in a circuit.
How to select proper Current Sensing Method?
Selecting the proper method for current sensing is not a difficult thing.
There are few factors need to be considered for choosing the right method, like:
How much accuracy is needed?
DC or AC measurement or both?
How much power consumption is required?
What is the current range and bandwidth to be measured?
Costing.
Other than those, acceptable sensitivity and interference rejection are also need to be considered.
As every factor can’t be satisfied, some trade-offs are made to compromise one feature with the other depending on the application requirement priority.
article/different-types-of-motors-used-in-electric-vehicles-ev
Types of Motors used in Electric Vehicles
and control techniques has created a space for various types of electric motors to be used in Electric Vehicles.
The electric motors used for automotive applications should have characteristics like high starting torque, high power density, good efficiency, etc.
Various types of Electric Motors used in Electric Vehicles
DC Series Motor
Brushless DC Motor
Permanent Magnet Synchronous Motor (PMSM)
Three Phase AC Induction Motors
Switched Reluctance Motors (SRM)
1. DC Series Motor
2. Brushless DC Motors
because the wheel is directly connected to the exterior rotor.
This type of motors does not require external gear system.
In a few cases, the motor itself has inbuilt planetary gears.
This motor makes the overall vehicle less bulky as it does not require any gear system.
It also eliminates the space required for mounting the motor.
There is a restriction on the motor dimensions which limits the power output in the in-runner configuration.
This motor is widely preferred by electric cycle manufacturers like Hullikal, Tronx, Spero, light speed bicycles, etc.
It is also used by two-wheeler manufacturers like 22 Motors, NDS Eco Motors, etc.
In this type, the rotor of the motor is present inside and the stator is outside like conventional motors.
These motor require an external transmission system to transfer the power to the wheels, because of this the out-runner configuration is little bulky when compared to the in-runner configuration.
Many three- wheeler manufacturers like Goenka Electric Motors, Speego Vehicles, Kinetic Green, Volta Automotive use BLDC motors.
Low and medium performance scooter manufacturers also use BLDC motors for propulsion.
Overloading the motor beyond a certain limit reduces the life of permanent magnets due to thermal conditions.
3. Permanent Magnet Synchronous Motor (PMSM)
For example, Toyota Prius, Chevrolet Bolt EV, Ford Focus Electric, zero motorcycles S/SR, Nissan Leaf, Hinda Accord, BMW i3, etc use PMSM motor for propulsion.
4. Three Phase AC Induction Motors
In permanent magnet motors, the magnets contribute to the flux density B.
Therefore, adjusting the value of B in induction motors is easy when compared to permanent magnet motors.
It is because in Induction motors the value of B can be adjusted by varying the voltage and frequency (V/f) based on torque requirements.
This helps in reducing the losses which in turn improves the efficiency.
Major automotive manufacturers like TATA motors have planned to use Induction motors in their cars and buses.
The two-wheeler manufacturer TVS motors will be launching an electric scooter which uses induction motor for its propulsion.
Induction motors are the preferred choice for performance oriented electric vehicles due to its cheap cost.
The other advantage is that it can withstand rugged environmental conditions.
Due to these advantages, the Indian railways has started replacing its DC motors with AC induction motors.
5. Switched Reluctance Motors (SRM)
Switched Reluctance Motors is a category of variable reluctance motor with double saliency.
Switched Reluctance motors are simple in construction and robust.
The rotor of the SRM is a piece of laminated steel with no windings or permanent magnets on it.
This makes the inertia of the rotor less which helps in high acceleration.
The robust nature of SRM makes it suitable for the high speed application.
SRM also offers high power density which are some required characteristics of Electric Vehicles.
Since the heat generated is mostly confined to the stator, it is easier to cool the motor.
The biggest drawback of the SRM is the complexity in control and increase in the switching circuit.
It also has some noise issues.
Once SRM enters the commercial market, it can replace the PMSM and Induction motors in the future.
Insights for Selecting the Right Motor for your EV
,one has to first list down the requirements of the performance that the vehicle has to meet, the operating conditions and the cost associated with it.
For example, go-kart vehicle and two-wheeler applications which requires less performance (mostly less than 3 kW) at a low cost, it is good to go with BLDC Hub motors.
For three-wheelers and two-wheelers, it is also good to choose BLDC motors with or without an external gear system.
For high power applications like performance two-wheelers, cars, buses, trucks the ideal motor choice would be PMSM or Induction motors.
Once the synchronous reluctance motor and switched reluctance motor are made cost effective as PMSM or Induction motors, then one can have more options of motor types for electric vehicle application.
article/an-overview-of-global-automotive-battery-management-system-market
An Overview of Global Automotive Battery Management Systems Market
sales as the bedrock upon which the innovative and technologically advanced battery management systems are developed and maintained.
, vis-à-vis voltage, temperature, current, among other electrical aspects, creates need for efficient battery management systems.
Automotive battery management systems help in improving the safety, lifespan, and performance of automotive batteries, and ultimately, the automobiles.
that can sync with vastly diverse performance requirements of various electric vehicles.
Thereby, an upsurge in demand for battery-based power can derive magnified growth prospects for the automotive battery management system market.
How Electric Vehicles Industry is Fueling Demand for Automotive Battery Management Systems
in the automotive industry has been growing in popularity among customers, triggering automotive manufacturers to modify their production strategies.
As customers are becoming more aware of the environmental impact of conventionally fueled vehicles and strict emission control regulations implemented by governing bodies around the world.
As a result, the global electric vehicle stock has grown rapidly in the past few years, and is expected to increase exponentially in the upcoming years.
According to the statistics published by the International Energy Agency (IEA), in 2017, the number of plug-in hybrid and electric cars on the roads increased by 54% as compared to that in 2016, to reach 1.1 million.
During the same year, over 250 million electric two-wheelers were sold, while the stock of electric buses increased from 345,000 in 2016 to 370,000.
IEA also found that the share of battery electric vehicles in the overall electric vehicles parc surged from 58% in 2013 to 62% in 2017.
A rapid uptake of electric vehicles reflects prominently in the plummeting costs of lithium ion batteries and innovations in battery management systems.
Along with increasing applications of batteries in automobiles, including electric vehicles, growing demand for lithium ion batteries in consumer electronic products has led to further battery cost reductions.
Thereby, burgeoning needs for battery performance improvements, not only in automotive applications but also in consumer electrics, is pushing end-users to adopt state-of-the-art battery management systems.
Innovations that Drive Automotive Battery Management System Market
for safe operation of electric vehicles and improving the lifespan of automotive batteries has bolstered growth of the automotive battery management system market.
The market reached US$ 1 billion in 2017, and with the growing adoption of technologically advanced automotive battery management systems, it is likely to expand 8x by the end of the next decade.
Increasing concerns about the driver’s safety have triggered the need for avoiding potential failures in the operation of electric vehicles.
Thereby, researchers, practitioners, and power engineers are working towards expanding the operational scope of battery management systems to monitor and balance voltages between cellsand avoid catastrophic failure in automotive batteries.
Leading stakeholders in the automotive battery management system market are pushing the envelope by focusing research & development activities to offer end-users more control over the operation of automotive battery management systems.
Growing adoption of next-generation wireless technologies is expected to emerge as a popular trend among automotive battery management system manufacturers in the foreseeable future.
Recently, a group of Chinese researchers developed a novel portable intelligent battery management system (PIBMS), which comprises of a battery measurement unit, a controller, and a data recording unit.
Researchers state that the intelligent battery management system can be connected to the battery through Bluetooth to transfer the real-time information about the status of the battery to a personal computer.
By offering this information about battery voltage and temperature at the charging station, the PIBMS could also help end-users to achieve adequate charging as well as efficiently protect the battery.
The company announced that with the wireless controls, its uStart battery management system could nearly double the lifespan of automotive batteries and eliminate one or two of the batteries throughout the life of a truck.
Tesla, Inc.
is an American automotive and energy company, which hinges on its battery technology innovations to maintain its strong position in the automotive market.
The company recently introduced its patented ‘Multi-Channel and Bi-Directional Battery Management Systemᾬ which features dynamic redundancy across its battery management system.
Dynamic redundancy is a unique feature of Tesla’s multi-channel and bi-directional architecture, which introduces a redundant command to activate a different and fully operational channel of a battery management system in case of a primary and secondary circuit failure in the system.
Recent developments in the automotive battery management systems and growing potential for electric vehicles in international markets is triggering leading automakers to search for highly innovative battery management solutions.
Top-tiered companies in the automotive industry, including Daimler AG and Mercedes-Benz, are collaborating with leading companies in the battery industry.
Wireless automotive battery management systems tailored to meet specific end-user requirements are witnessing high demand in automotive markets.
Asia Pacific to Remain the Most Lucrative Markets for Automotive Battery Management Systems
Growth of the automotive battery management system market hinges on the electrification trend growing in the automotive industry.
Increasing sales of battery-operated electric vehicles will create lucrative opportunities for automotive battery management system manufacturers.
Leading stakeholders in the automotive battery management system market are eyeing opportunities to expand their geographical footprint, and eventually, to consolidate their position in the global market.
After recovering from the economic crisis, the automotive industry has witnessed profitable growth.
Emerging economies in the Asia Pacific region have been bolstering the global automotive production and sales with increased disposable income of consumers and rapid industrial growth in developing countries, such as China and India.
Consumers in the developing countries in Asia Pacific are becoming aware of environmental impact of harmful emissions increased with the escalating sales of conventionally-fueled vehicles.
Governing bodies has also enacted laws to reduce emissions through transportation and promote battery-operated or electric vehicles.
As a result, China accounted for more than half the electric car sales across the world.
Chinese government had been implementing strict emission control rules to boost electric vehicles on the roads, and consequently, electric car sales in the country increased by 72% over 2016 to record the sales of 580,000 electric cars in 2017, according to the statistics by IEA.
Electrification of the Chinese automotive industry is limited to electric cars but the scope expands to include other modes of transportation such as two wheelers and buses.
China holds a whopping 99% share in the global stock of both electric bus and electric two wheelers, which signifies profitable opportunities for automotive battery management system manufacturers in the country.
Automotive Battery Management System Sales to Surge in European Countries
The European Union is also emerging as one of the leading regional markets for electric vehicles, as well as for automotive battery management systems.
European countries, including Germany and NORDIC countries, are likely to emerge as intensely competitive markets, which is attributed to burgeoning sales of electric vehicles.
Norway accounted for more than one-third of the global electric cars stock in 2017, while the Iceland and Sweden held 18% share in the global electric vehicles parc, according to IEA.
The Electric Vehicles Initiative (EVI) by the European Commission launched the EV 30@30 campaign in 2017 to establish the goal to account for over 30% market share in the global electric vehicles market by 2030.
The campaign is galvanizing the private and public sector to expand the potential for electric vehicle sales in European countries, which is expected to create positive growth environment for automotive battery management system market players in the European markets.
In addition, the ongoing developments in charging infrastructures in the European Union is expected to shape the future of battery industry and automotive battery management system market in the region.
Thereby, leading players in the automotive battery management system market are adopting strategies to capitalize on increasing demand for electric vehicles in Europe to boost profitable sales of efficient automotive battery management systems.
The automotive battery management system market in the Asia Pacific region (excluding Japan) reached US$ 388 million in 2017, which was more than one-third of the global market revenues in the same year.
The region is likely to maintain its dominance in the automotive battery management system market in the coming decade.
The European Union is likely to emerge as a fast-growing market for automotive battery management system in the foreseeable future, creating highly lucrative growth opportunities for market players.
article/selecting-the-right-switching-regulator-for-your-application
Selecting the Right Switching Regulator for Your Application
This involves changing the value of DC voltage at the input to a higher or lower value at the output.
The components/modules used to achieve these tasks are generally referred to as voltage regulators.
They generally have the ability to supply a constant output voltage which is higher or lower than the input voltage and they are commonly used to supply power to components in designs where you have sections at different voltages.
They are also used in traditional power supplies.
;
Linear Regulators
Switching Regulators
on the other hand are capable of either stepping up or down the voltage applied at the input depending on the architecture.
They achieve voltage regulation using a on/off switching process of a transistor which controls the voltage available at the regulators output.
Compared to linear regulators, Switching regulators are usually more expensive and far more efficient.
to determine if it fits your particular use case.
Details will also be provided on interpreting the different ways in which different manufacturers present information on parameters like temperature, load etc.
Types of Switching Regulators
There are essentially three types of switching regulators and the factors to put into consideration depends on which of the types is to be used for your application.
The three types are ;
Buck Regulators
Boost regulators
Buck Boost Regulators
applied at the input to a lesser voltage at the output.
Thus, their rated input voltage is usually higher than their rated output voltage.
A basic schematics for a buck converter is shown below.
is shown below.
produces an inverted (negative) output voltage which can be greater or less than the input voltage based on the duty cycle.
The basic buck-boost switch mode power supply circuit is given below.
The buck-boost converter is a variation of the boost converter circuit in which the inverting converter only delivers the energy stored by the inductor, L1, into the load.
The selection of any of these three switching regulator types, depends solely on what is required by the system being designed.
Irrespective of the type of regulator to be used, It is important to ensure the specifications of the regulators meets the requirements of the design.
Factors to Consider when Selecting a Switching Regulator
The design of a switching regulator depends in a large measure on the power IC used for it, thus most of the factors to consider will be the specifications of the power IC used.
It is important to understand the specifications of Power IC and what they signify so as to ensure you select the right one for your application.
Irrespective of your application, running a check on the following factors will help you reduce the time spent on selection.
It is usually specified within the data sheet and as a designer, its important to ensure that the input voltage for your application, falls within the Input Voltage range specified for the IC.
While certain data sheets may only specify for the maximum input voltage, it is better to check the data sheet to be sure there is no mention of the minimum input range before making any assumptions.
When voltages higher than the max input voltage is applied, the IC’s usually gets fried out but it usually stops operating or operate abnormally when voltages lower than the minimum input voltage is applied, all depending on the protective measures in place.
One of the protective measures usually applied to prevent damage to ICs when out of range voltages are supplied at the input is the Under-Voltage Lock Out (UVLO), checking if this is available may also help your design decisions.
In ICs without variable output option, this is usually a single value.
It is important to ensure that your required output voltage is within the range specified for the IC and with a good factor of safety as difference between the maximum output voltage range and the output voltage you require.
as a general rule the minimum output voltage cannot be set to a voltage level lower than the internal reference voltage.
Depending on your application (buck or boost), the minimum output range can either be greater than the input voltage(boost) or way lesser than the input voltage(buck).
For some ICs, Only the maximum output current is specified as a measure of safety and to help the designer ensure the regulator will be able to deliver the current required for the application.
For other ICs, both the minimum and maximum ratings are provided.
This could be very useful in planning power management techniques for your application.
In selecting a regulator based on the IC’s output current, it is important to ensure a margin of safety exists between the maximum current required by your application and the maximum output current of the regulator.
It is important to ensure the max output current of the regulator is higher than your required output current by at least 10 to 20%, as the IC may generate a high amount of heat when operating at maximum levels continuously and could be damaged by the heat.
Also the efficiency of the IC reduces when operating at maximum.
The TJ temperature refers to the highest operating temperature of the transistor, while the ambient temperature refers to the temperature of the environment around the device.
If the Operating temperature range is defined in terms of the ambient temperature, it doesn’t necessarily mean the regulator can be used over the full temperature range.
It is important to factor in the factor of safety and also factor in the planned load current and the accompanying heat as the combination of this and the ambient temperature is what makes up the junction temperature which should also not be exceeded.
Staying within the operating temperature range is critical to the proper, continuous operation of the regulator as excessive heat could lead to abnormal operation and catastrophic failure of the regulator.
It is thus important to pay attention to the ambient heat in the environment which the device will be used and also determine the possible amount of heat that will be generated by the device as a result of the load current before determining if the specified operating temperature range of the regulator works for you.
Its important to note that certain regulators could also fail in extremely cold conditions and its worth paying attention to the minimum temperature values if the application will be deployed in cold environment.
based regulators, the frequency is usually fixed while in Pulse Frequency Modulation.
The switching frequency affects the parameters of the regulator like the ripple, the output current, the maximum efficiency, and the response speed.
The design for the switching frequency always involve the use of matching inductance values, such that the performance of two similar regulators with different switching frequency will be different.
If two similar regulators at different frequencies are considered, it will be discovered that, the maximum current for instance will be low for the regulator operating at a lower frequency compared to that of the regulator at high frequency.
Also, parameters like ripple will be high and the response speed of the regulator will be low at low frequency, while the ripple will be low and response speed, high at high frequency.
The switching action associated with switching regulators generates noise and related harmonics which could affect the performance of the overall system, especially in systems with RF components and audio signals.
While the noise can be reduced by means of a filter etc., it can really reduce the signal to noise ratio (SNR) in circuits that are sensitive to noise.
It is thus important to be sure the amount of noise generated by the regulator won’t affect the overall performance of the system.
Theoretically, the efficiency of a switching regulator is hundred percent, but this is not usually true in practice as the resistance of FET switch, diode voltage drop and ESR of both inductor and output capacitor reduces the overall efficiency of the regulator.
While most modern regulators offer stability across wide operation range, the efficiency varies with use and for instance is greatly reduced as the current drawn from the output increases.
Load regulation is a measure of the ability of a voltage regulator to maintain a constant voltage at the output irrespective of the changes in the load requirement.
This essentially includes reducing the size of the electronics component and invariably reducing the number of components that make up each section of the device.
A Small size power system not only helps reduce the overall size of the project, but it also helps create room to which extra product features can be cramped in.
Depending on the goals of your project, ensure the form factor/package size you go with will fit into your space budget.
While making selections based on this factor, it is also important to factor in the size of the peripheral components required by the regulator to function.
For instance, the use of High frequency ICs permit the use of output capacitors with low capacitance and inductors, resulting in a reduced component size and vice versa.
Identifying all of this and comparing with your design requirements will quickly help you determine which regulator should be crossed of and which should feature in your design.
Do share which factor you think i missed out and any other comments via the comment section.
Till Next time.
tutorial/serial-communication-protocols
Serial Communication Protocols
More specifically, the data bits are transmitted one at a time in sequential manner over the data bus or communication channel in Serial Communication.
Types of Communication Protocols
, USB, 1-Wire, and SATA etc.
will be discussed.
Serial communication is the most widely used approach to transfer information between data processing peripherals.
Every electronics device whether it is Personal Computer (PC) or Mobile runs on serial communication.
The protocol is the secure and reliable form of communication having a set of rules addressed by the source host (sender) and destination host (receiver) similar to parallel communication.
Transmission Modes in Serial Communication
As already said above that in serial communication data is sent in the form of bits i.e.
binary pulses and it is well known that, binary one represents the logic HIGH and zero represents the logic LOW.
There are several types of serial communication depending on the type of transmission mode and data transfer.
The transmission modes are classified as Simplex, Half Duplex and Full Duplex.
technique.
The well-known examples of simplex method are Television and Radio.
In half duplex method both sender and receiver can be active but not at the same time.
So if the sender is transmitting then receiver can accept but cannot send and similarly vice versa.
The well-known examples of the half duplex is the internet where the user sends a request for a data and the gets it from server.
In full duplex method, both receiver and transmitter can send data to each other at the same time.
The well-known example is mobile phone.
Apart from this, for appropriate data transmission, the clock plays important role and it is one of the primary source.
Malfunction of the clock results in unexpected data transmission even sometimes data loss.
So, the clock synchronisation becomes very important when using serial communication.
Clock Synchronization
The clock is different for serial devices and it is classified in two type viz.
Synchronous Serial Interface and Asynchronous Serial Interface.
It is a point-to-point connection from a master to slave.
In this type of interface, all the devices use single CPU bus to share data and clock.
The data transmission becomes faster with same bus to share clock and data.
Also there is no mismatch in baud rate in this interface.
In transmitter side, there is a shift of the data onto serial line providing the clock as a separate signal as there is no start, stop and parity bits are added to data.
In receiver side, the data is being extract using the clock provided by the transmitter and converts the serial data back to the parallel form.
The well-known examples are I2C and SPI.
Other Terms Related to Serial Communication
Apart from Clock Synchronization there are certain things to remember when transferring data serially such as Baud Rate, Data bit selection (Framing), Synchronisation and error checking.
Let’s discuss these terms in brief.
Baud rate is rate at which the data is transferred between the transmitter and receiver in the form of bits per second (bps).
The most commonly used baud rate is 9600.
But there are other selection of baud rate such as 1200, 2400, 4800, 57600, 115200.
The more the baud rate will be fats the data will be transferred at a time.
Also for the data communication the baud rate has to be same for both transmitter and receiver.
Framing is referred to the number of data bits to be sent from transmitter to receiver.
The number of data bits differs in case of application.
Most of the application uses 8 bits as the standard data bits but it can be selected as 5, 6 or 7 bits also.
Synchronization Bits are important to select a chunk of data.
It tells the start and end of the data bits.
The transmitter will set start and stop bits to the data frame and the receiver will identify it accordingly and do the further processing.
The error control plays an important role while serial communication as there are many factors which affects and adds the noise in the serial communication.
To get rid of this error the parity bits are used where parity will check for even and odd parity.
So if the data frame contains the even number of 1’s then it is known as even parity and the parity bit in the register is set to 1.
Similarly if the data frame contains odd number of 1’s then it is known as odd parity and clears the odd parity bit in the register.
Protocol is just like a common language that system uses to understand the data.
As described above, the serial communication protocol is divided into types i.e.
Synchronous and Asynchronous.
Now the both will be discuss in detail.
Synchronous Serial Protocols
are used in different projects because it is one of the best resources for onboard peripherals.
Also these are the widely used protocols in major applications.
The Serial Peripheral Interface (SPI) is a synchronous interface which allows several SPI microcontrollers to be interconnected.
In SPI, separate wires are required for data and clock line.
Also the clock is not included in the data stream and must be furnished as a separate signal.
The SPI may be configured either as master or as a slave.
The four basic SPI signals (MISO, MOSI, SCK and SS), Vcc and Ground are the part of data communication.
So it needs 6 wires to send and receive data from slave or master.
Theoretically, the SPI can have unlimited number of slaves.
The data communication is configured in SPI registers.
The SPI can deliver up to 10Mbps of speed and is ideal for high speed data communication.
Most of the microcontrollers have inbuilt support for SPI and can be directly connected SPI supported device:
SPI Communication with PIC Microcontroller PIC16F877AHow to Use SPI Communication in STM32 MicrocontrollerHow to use SPI in Arduino: Communication between two Arduino Boards
Inter integrated circuit (I2C) two-line communication between different ICs or modules where two lines are SDA (Serial Data Line) and SCL (Serial Clock Line).
Both the lines must be connected to a positive supply using a pull up resistor.
I2C can deliver speed up to 400Kbps and it uses 10 bit or 7 bit addressing system to target a specific device on the i2c bus so it can connect up to 1024 devices.
It has limited length communication and is ideal for onboard communication.
I2C networks are easy to setup since it uses only two wires and new devices can simply be connected to the two common I2C bus lines.
Same like SPI, microcontroller generally have I2C pins to connect any I2C device:
How to use I2C Communication in STM32 MicrocontrollerI2C Communication with PIC Microcontroller PIC16F877How to use I2C in Arduino: Communication between two Arduino Boards
USB (Universal Serial Bus) is widely protocol with different versions and speeds.
A maximum of 127 peripherals can be connected to a single USB host controller.
USB acts as "plug and play" device.
The USB are used in almost devices such as keyboards, printers, media devices, cameras, scanners and mouse.
It is designed for easy installation, faster data rated, less cabling and hot swapping.
It has replaced the bulkier and slower serial and parallel ports.
USB uses differential signalling to reduce interference and allow high-speed transmission over a long distance.
A differential bus is built with two wire, one of represents the transmitted data and the other its complement.
The idea is that the 'average' voltage on the wires does not carry any information, resulting in less interference.
In USB, the devices are allowed to draw a certain amount of power without asking the host.
USB uses only two wires to for data transfer and are faster than the serial and parallel interface.
USB versions supports different speeds such as 1.5Mbps (USB v1.0), 480 Mbps (USB2.0), 5Gbps (USB v3.0).
Length of individual USB cable can reach up to 5 meters without a hub and 40 meters with hub.
The Controller Area Network (CAN) is used in e.g.
automotive to allow communication between ECUs (Engine Control Units) and sensors.
The CAN protocol is robust, low-cost and message based and covers in many applications - e.g.
cars, trucks, tractors, industrial robots.
The CAN bus system allows for central error diagnosis and configuration across all ECUs.
CAN messages are prioritized via IDs so that the highest priority IDs are non-interrupted.
Each ECU contains a chip for receiving all transmitted messages, decide relevance and act accordingly - this allows easy modification and inclusion of additional nodes (e.g.
CAN bus data loggers).
The applications include start/stop of vehicles, collision avoidance systems.
The CAN bus systems can provide speed up to 1Mbps.
MICROWIRE is a 3Mbps [full-duplex] serial 3-wire interface essentially a subset of the SPI interface.
Microwire is a serial I/O port on microcontrollers, so the Microwire bus will also be found on EEPROMs and other Peripheral chips.
The 3 lines are SI (Serial Input), SO (SerialOutput) and SK(Serial Clock).
The Serial Input (SI) line to the microcontroller, SO is the serial output line, and SK is the serial clock line.
Data is shifted out on the falling edge of SK, and is valued on the rising edge.
SI is shifted in on the rising edge of SK.
An additional bus enhancement to MICROWIRE is called MICROWIRE/Plus.
The main difference between the two buses seems to be that MICROWIRE/Plus architecture within the microcontroller is more complex.
It supports speeds up to 3Mbps.
Asynchronous Serial Protocols
that is common to both devices.
Each device independently listens and sends digital pulses that represent bits of data at an agreed-upon rate.
Asynchronous serial communication is sometimes referred to as Transistor-Transistor Logic (TTL) serial, where the high voltage level is logic 1, and the low voltage equates to logic 0.
Almost every microcontroller on the market today has at least one Universal Asynchronous Receiver-Transmitter (UART) for serial communication.
The examples are RS232, RS422, RS485 etc.
(Recommended Standard 232) is very common protocol used to connect different peripherals such as Monitors, CNCs etc.
The RS232 comes in male and female connectors.
The RS232 is point-to-point topology with maximum one device connected and covers distance up to 15 meters at 9600 bps.
Information on the RS-232 interface is transmitted digitally by logical 0 and 1.
The logical "1" (MARK) corresponds to a voltage in the range from -3 to -15 V.
The logical "0" (SPACE) corresponds to a voltage in the range from +3 to +15 V.
It comes in DB9 connector which has 9 pinouts such as TxD, RxD, RTS, CTS, DTR, DSR, DCD, GND.
The RS422 is similar to RS232 which allows to simultaneously send and receive messages on separate lines but uses a differential signal for this.
In the RS-422 network, there can only be one transmitting device and up to 10 receiving devices.
The data transfer speed in RS-422 depends on the distance and can vary from 10 kbps (1200 meters) to 10 Mbps (10 meters).
The RS-422 line is 4 wires for data transmission (2 twisted wires for transmission and 2 twisted wires for receiving) and one common GND ground wire.
The voltage on the data lines can be in the range from -6 V to +6 V.
The logical difference between A and B is greater than +0.2 V.
Logical 1 corresponds to the difference between A and B less than -0.2 V.
The RS-422 standard does not define a specific type of connector, usually it can be a terminal block or a DB9 connector.
Since RS485 uses multi-point topology, it is most used in the industries and are industry preferred protocol.
RS422 can connect 32 line drivers and 32 receivers in a differential configurations but with the help of additional repeaters and signal amplifiers up to 256 devices.
The RS-485 does not define a specific type of connector, but it is often a terminal block or a DB9 connector.
The speed of operation also depends on the length of the line and can reach 10 Mbit / s at 10 meters.
The voltage on the lines is in the range from -7 V to +12 V.
There are two types of RS-485 such as half duplex mode RS-485 with 2 contacts and full duplex mode RS-485 with 4 contacts.
To learn more about using RS485 with other microcontrollers, check the links:
RS-485 MODBUS Serial Communication using Arduino UNO as SlaveRS-485 Serial Communication between Raspberry Pi and Arduino UnoRS485 Serial Communication between Arduino Uno and Arduino NanoSerial Communication between STM32F103C8 and Arduino UNO using RS-485
Conclusion
Serial Communication is one of the widely used communication interface systems in electronics and embedded systems.
The data rates can be different for different applications.
The Serial Communication Protocols can play decisive role when dealing in this kind of applications.
So choosing the right Serial protocol becomes very important.
article/brushed-vs-brushlless-motor-operation-construction-applications
Brushed vs Brushless Motors: Operation, Construction and Applications
They are usually referred to as the exact opposite of generators as they operate on similar principles and can theoretically be converted to generators.
They are essentially use in situations where rotational motion is needed and they find applications in appliances (vibration motors), robots, medical equipments, toys, and much more.
(which are our focus for today) on the other hand are usually smaller and are used in battery (or plugged in DC sources) based applications where significantly less amount of work is required compared to AC motors.
They find applications in several devices ranging from everyday devices like shaving clippers to toys for kids, robots, and drones among others.
including;
Brushed DC Motor
Brushless DC Motors
Servo Motors.
Operation Principle and Construction
between the ends of the conductor.
Based on these laws, electric motors comprises of two main part; A permanent magnet and a bunch of conductors wound into a coil.
By applying electricity to the coil it becomes a magnet and based on the fact that magnets repel at like poles and attract at unlike poles, a rotational motion is achieved.
Brushed DC Motor
(Rotor) on which components like the commutator, brushes, and split ring all of which is placed around the motor shaft.
When power is supplied to the motor (through battery or through an AC to DC plugged in source), electricity flows from the source to the armature through the brushes which are usually located on opposite sides of the motors shaft.
The brushes (whose presence in the design is a major factor behind the motor’s name), transfer electric current to the armature through physical contact with the commutator.
As soon as the armature (the coil of wire) is energized, it begins to behave like a magnet and at that point its poles start repelling the poles of the permanent magnet which makes up stator.
As the poles repel, the motor shaft to which the armature is attached begins to rotate with a speed and torque that depends on the strength of the magnetic field around the armature.
The strength of the magnetic field is usually a function of the voltage applied at the brushes and the strength of the permanent magnet used for the stator.
Brushless DC Motors
Even though they use the same principle of electromagnetism, brushless motors on the other hand are more complex.
They are a direct result of efforts made to improve the efficiency of Brushed DC motors and can be simply described as motors who do not adopt the use of brushes for commutation.
However, the simplistic nature of that description gives way to questions on how the motor gets powered and how motion is achieved without brushes which I will try to explain.
, sensors (e.g hall sensor) are placed along the poles of the motor to provide feedback to the control circuitry to help it estimate rotor position.
There are three popular algorithms employed for sensor-based commutation;
Trapezoidal commutation
Sinusoidal commutation
Vector (or field-oriented) control.
Each of these control algorithm has its pros and cons and the algorithms can be implemented in different ways depending on the software and the design of the electronics hardware to make necessary changes.
on the other hand, instead of sensors being placed within the motors, the control circuitry is designed to measure the back EMF to estimate rotor position.
This algorithm performs pretty well and is at a reduced cost as the cost of the hall sensors is eliminated but its implementation is a lot more complex compared to the sensor based algorithms.
Advantage and Disadvantages
and thus have really high efficiency, require zero maintenance and last longer than brushed DC motors.
due to the simple nature of their design.
Brushless DC motors on the other hand are quite expensive due to their complex design and the extra cost of the additional electronics components (controllers) required to drive them.
Applications
While brushless DC motors are more popular these days, brushed DC motors are still used in day to day home appliances, kids toys, and in industrial applications due to the ease with which their speed to torque ratio can be varied.
Due to their low cost, they are used in applications where the host device could fail before the motors.
Brushless DC motors on the other hand have found applications in all sort of devices, from medical equipments, robots and drones to electric cars, power tools etc.
They are essentially used in applications that require high efficiency, longevity and are worth the cost.
Factors to consider when selecting between the Brushless and Brushed DC Motors
Asides speed, torque, power rating and other basic requirements for your application below are three factors I feel could also be good to consider when making a decision on the type of motor to deploy for your application.
Duty Cycle/ Service Life
Efficiency
Control/Actuation
Cost
motors but there have been cases of Iron-less core brushed motors with superior efficiency compared to equivalent brushless motors.
However, it is important to evaluate the overall required efficiency and compare it with that of each motor before making a decision.
In most cases where efficiency is the deciding factor, brushless DC motors usually win.
) makes it easier to interface a BLDC with a microcontroller.
The complexity of the design of brushless DC motors makes them really expensive when compared with brushed DC motors.
Be sure the extra costs are within affordable limits for the project before going for brushless DC motors.
Also consider the cost of the other accessories required for the use of BLDCs before making a decision.
tutorial/what-is-capacitor-leakage-current-and-how-to-reduce-it
What is Capacitor Leakage Current and How to Reduce It
Capacitor also have a different types of ratings, such as working voltage, working temperature, tolerance of the rated value and leakage current.
Apart from selecting the perfect capacitor with proper leakage, circuit should also have the ability to control the leakage current.
So first we should have a clear understanding of capacitor leakage current.
Relation with Dielectric Layer
The leakage current of a capacitor has a direct relationship with the dielectric of the capacitor.
Let's see the below image -
, etc.
The Insulator and the flow of current can be demonstrated by using a simple capacitor and resistor.
and the capacitor is used to replicate the actual capacitor.
Since the resistor has a very high value of resistance, the current flowing through the resistor is very low, typically in a number of nano-amperes.
Insulation resistance is dependent on the type of dielectric insulator as different type of materials changes the leakage current.
The low dielectric constant provides very good insulation resistance, resulting in a very low leakage current.
For example, polypropylene, plastic or teflon type capacitors are the example of low dielectric constant.
But for those capacitors, the capacitance is very less.
Increasing the capacitance also increases the dielectric constant.
Electrolytic capacitors typically have very high capacitance, and the leakage current is also high.
Dependent Factors for Capacitor Leakage Current
Capacitor Leakage Current generally depends on below four factors:
Dielectric Layer
Ambient Temperature
Storing Temperature
Applied Voltage
1. The Dielectric layer is not working properly
Capacitor construction requires a chemical process.
The dielectric material is the main separation between the conductive plates.
As the dielectric is the main insulator, the leakage current has major dependencies with it.
Therefore, if the dielectric is tempered during the manufacturing process, it will directly contribute to the increase of leakage current.
Sometimes, the dielectric layers have impurities, resulting in a weakness in the layer.
A weaker dielectric decreases the flow of current which is further contributed to the slow oxidation process.
Not only this, but improper mechanical stress also contribute to the dielectric weakness in a capacitor.
2. Ambient Temperature
The capacitor has a rating of the working temperature.
The working temperature can be ranged from 85 degree Celsius to the 125 degree Celsius or even more.
As the capacitor is a chemically composed device, the temperature has a direct relationship with the chemical process inside the capacitor.
The leakage current generally increases when the ambient temperature is high enough.
3. Storage of the Capacitor
When the capacitors are stored, the oxide layer is attacked by the electrolyte material.
The oxide layer starts to dissolve in the electrolyte material.
The chemical process is different for different type of electrolyte material.
The water-based electrolyte is not stable whereas inert solvent-based electrolyte contributes less leakage current due to the reduction of the oxidation layer.
However, this leakage current is temporary as the capacitor has self-healing properties when applied to a voltage.
During the exposure to a voltage, the oxidation layer starts to regenerate.
4. Applied Voltage
Each capacitor has a voltage rating.
Therefore, using a capacitor above the rated voltage is a bad thing.
If the voltage increases, the leakage current also increases.
If the voltage across the capacitor is higher than the rated voltage, the chemical reaction inside a capacitor creates Gases and degrade the Electrolyte.
If the capacitor is stored for a long time such as for years, the capacitor is needed to be restored into the working state by providing rated voltage for a few minutes.
During this stage, the oxidation layer built up again and restores the capacitor in a functional stage.
How to reduce Capacitor Leakage Current to improve the Capacitor Life
As discussed above a capacitor has dependencies with many factors.
The first question is how the capacitor life is calculated? The answer is by calculating the time until the electrolyte is run out.
The electrolyte is consumed by the oxidation layer.
Leakage current is the primary component for the measurement of how much the oxidation layer is hampered.
Therefore, the reduction of leakage current in the capacitor is a major key component for the life of a capacitor.
The precaution needs to be taken that the dielectric layer is not damaged or hampered.
Improper temperature affects the capacitor electrolyte which further downgrades the oxidation layer quality.
Make sure to operate the capacitors in proper ambient temperature, less than the maximum value.
To overcome this, each capacitor comes with a data sheet where the manufacturer provides a safe soldering temperature rating and maximum exposure time.
One needs to be careful about those ratings for the safe operation of the respective capacitor.
This is also applicable for the Surface Mount Device (SMD) capacitors too, the peak temperature of reflow soldering or wave soldering should not exceed than the maximum allowable rating.
This is due to the imbalance of leakage current divide the voltage and split between the capacitors.
The split voltage can be different for each capacitor and there can be a chance that the voltage across a particular capacitor could be excess than the rated voltage and the capacitor start to malfunction.
To overcome this situation, two high-value resistors are added across the individual capacitor to reduce the leakage current.
By using the balancing technique, the voltage difference influenced by leakage current can be controlled.
tutorial/what-is-fpga-introduction-and-programming-tools
Introduction to FPGA and It's Programming Tools
because of their cheap cost, good support, easy availability, large community, versatility, programming etc.
But other than that microprocessors have some limitations such as the instructions set, sequential execution of programs (sequential processing), lack of flexibility and reusability etc.
However the FPGA can overcome these limitations as FPGAs have parallel execution of programs and it is flexible & reusable means it can be reprogrammed over and over for different tasks.
What is FPGAand How it is different from Microcontroller
The FPGA will behave like the digital circuit once it is loaded with a bit file.
when it comes to building any device.
FPGAs takes considerably much more time to set-up while the microcontrollers are available readilybuilt for specific applications.
FPGA Architecture
Each block will be discussed below in brief.
CLB (Configurable Logic Block): These are the basic cells of FPGA.
It consists of one 8-bit function generator, two 16-bit function generators, two registers (flip-flops or latches), and reprogrammable routing controls (multiplexers).
The CLBs are applied to implement other designed function and macros.
Each CLBs have inputs on each side which makes them flexile for the mapping and partitioning of logic.
I/O Pads or Blocks: The Input/Output pads are used for the outside peripherals to access the functions of FPGA and using the I/O pads it can also communicate with FPGA for different applications using different peripherals.
Switch Matrix/ Interconnection Wires: Switch Matrix is used in FPGA to connect the long and short interconnection wires together in flexible combination.
It also contains the transistors to turn on/off connections between different lines.
When FPGAs are needed
A programmer has to abide by the restrictions while developing code.
So in this scenario also, the FPGAs have advantage.
In the case of microcontrollers, you have to account for the time taken by ISR to resolve an interruption.
You can rewire an FPGA easily just by reprogramming it.
The configuration in an FPGA is loaded on the configurable logic cells when the power is switched on.
However, they also have the drawbacks of prototype operation and complexity of configuration.
So, the FPGAs can be chosen with these advantages over microcontrollers.
Let’s start the FPGA programming and emphasize more on FPGA programming.
Programming FPGA (Field-Programmable Gate Array)
Programming of FPGAs is done by HDLs (Hardware Description Languages).
There are several HDLs are available but the VHDL and Verilog are widely used HDLs.
Even though there are some similarity between HDL code and high-level software programming language but the two are fundamentally different.
Software codes are a sequence of operations and perform the processing in sequence whereas HDL code is a schematic that uses text to introduce components and create interconnections with parallel processing.
respectively.
The important steps involve in programming FPGAs are as follows.
Synthesis: The First step is the synthesis which takes HDL code and translate into netlist which is a textual description of a circuit diagram or schematic.
Simulation: After synthesis, the next step involves the simulation which is used to verify if the design specified in the netlist functions correctly.
Convert netlist into Binary Format: Once the design is verified, the next is convert netlist into binary format.
The components and connections are mapped to CLBs and the design is placed and routed to fit onto the target FPGA (i.e Place and Route).
Perform Second Simulation: To see the design quality, a second simulation is performed.
Generate Bit File: Finally a bit file is generated to load the design onto FPGA (A .bit file is a configuration file which is used to program all of the resources within FPGA).
Verify and Debug: At last, using different tools the design is verified and debugged while it is running on the FPGA.
Unlike the Hardware Design Flow, there is no requirement for pre-implementation simulation step in Software Design Flow.
Also, the compile times for software are much shorter than implementation times for hardware designs so it is practical to recompile code and perform debugging as an iterative process.
The Programming Languages and Tools
As mentioned above there are several programming languages and tools available to program and debug FPGAs but most widely used are VHDL and Verilog.
Both VHDL and Verilog are well established and wide support HDLs.
In terms of program FPGA, one needs to forget the software coding behaviour and start thinking about logic gates and circuits to implement the functionality that one wants to run on FPGAs.
such as:
Both languages provide structures to describe the inherently parallel nature of FPGA / ASIC development.
Due to their initial use to describe the behaviour of the circuits prior to the generation of synthesis tools, these languages also support test benches to test the design being implemented.
is a graphical language which gives a completely different way of programming a FPGA.
LabVIEW FPGA is the FPGA compilation uses a cloud-based option, which speeds up the compilation time significantly.
is the language which can play a vital role and should be studied.
The MATLAB is generally used to generate filters for signal processing, develop image processing algorithms and almost any other algorithm.
But apart from this, it is possible to go from MATLAB model to FPGA using the HDL coder.
The traceability enables the high integrity applications can be developed using this approach.
HDL coder enables to perform hardware (FPGA) in the loop testing and co-simulation to see the difference between the original algorithm and the implemented hardware algorithm, which helps to explore the design space.
Conclusion
The initial experience with FPGAs cannot be as expected but after practicing several times, it can be handy to program FPGA.
Also the modern FPGAs are high performance devices and one can find these FPGAs with potential advantages in some applications which needs versatility.
tutorial/what-is-inductor-coupling-series-and-parallel-combinations
Inductor Coupling - Series & Parallel Combinations
The combinations of components are together to create coupled circuits.
The meaning of coupled circuit is that the energy transfer takes place from one to other when either of the circuits is energized.
Major components in the electronics circuit are coupled by either conductively or electromagnetically.
combinations will be discussed.
Mutual Inductance
In the previous article, we discussed the self-inductance of an inductor and its parameter.
During the self-inductance related operation, there was no mutual inductance took place.
When the rate of current change occurs, a voltage is induced inside a coil.
Which can be further demonstrated using the below formula where,
Is the current flowing through the coil, and the inductance of the coil is L.
V(t) = L {di(t)/dt}
The above condition is true only for the self-inductance related circuit element where two terminals are present.
In such a case, no mutual inductance is taken into the order.
Now, at the same scenario, if two coils are situated in a close distance, the inductive coupling will happen.
The two separate coils are now magnetically coupled.
Now, interestingly, if one of the coils faces the rate of current change, the other coil will induce a voltage which is directly proportional to the rate of current change in the other coil.
Therefore, when a voltage source V1 is applied in the coil L1, the current i1 will start to flow through the L1.
The rate of current change produces a flux which flows through the magnetic core and produces a voltage in the coil L2.
The rate of current change in L1 also changes the flux which can further manipulate the induced voltage in L2.
can be calculated in the below formula-
V2 = M {di1(t)/dt}
Same for the first coil L1, the mutually induced voltage due to mutual inductance for the first coil can be ᾍ
V2 = M {di2(t)/dt}
As the inductance induces voltage with the rate of current change, mutual inductance also induces a voltage, which is termed as mutual voltage M(di/dt).
This mutual voltage can be positive or negative which is highly dependable on the physical construction of the coil and the direction of the current.
DOT Convention
is an essential tool to determine the polarity of the mutually induced voltage.
As the name suggests, the dot mark which is in a circular shape is a special symbol which is used at the end of two coils in mutually coupled circuits.
This dot also provides the information of the winding construction around its magnetic core.
In the above circuit, two mutually coupled inductors are shown.
These two inductors have self-inductances of L1 and L2.
The voltages V1 and V2 are developed across the inductors are the result of current entering into the inductors on the dotted terminals.
By assuming that the mutual inductance of those two inductors is M, The induced voltage can be calculated using the below formula,
For the first inductor L1, the induced voltage will be -
V1 = L1(di1/dt) ± M(di2/dt)
The same formula can be used for calculating the induced voltage of the second Inductor,
V2 = L2(di2/dt) ± M(di1/dt)
Therefore, the circuit contains two types of induced voltage, the induced voltage due to self-inductance and the mutually induced voltage due to the mutual inductance.
The induced voltage depending on the self-inductance is calculated using the formula V = L(di/dt) which is positive, but the mutually induced voltage can be negative or positive depending on the winding construction as well as the flow of current.
The use of dot is an important parameter to determine the polarity of this mutually induced voltage.
In a coupled circuit where two terminals belong two different coils and identically marked with dots, then for the same direction of the current which is relative to like terminals, the magnetic flux of self and mutual induction in each coil will add up together.
Coefficient of Coupling
where L1 is the self inductance of the first coil and the L2 is the self inductance of the second coil.
Two inductively coupled circuits are linked using the magnetic flux.
If the entire flux of one inductor is coupled or linked the other inductor is called perfect coupling.
During this situation, the K can be expressed as 1 which is the short form of 100% coupling.
The coefficient of coupling will always less than the unity and the maximum value of the coefficient of coupling can be 1 or 100%.
The mutual inductance is highly dependable on the coefficient of coupling between the two inductively coupled coil circuits.
If the coefficient of coupling is higher so the mutual inductance will be higher, on the other side, if the coefficient of coupling is at a lower amount that will highly decrease the mutual inductance in the coupling circuit.
The coupling coefficient cannot be a negative number and it has no dependencies on the direction of current inside the coils.
The coupling coefficient depends on the core materials.
In iron or ferrite core materials the coupling coefficient can be very high like 0.99 and for the air core, it can be as low as 0.4 to 0.8 depending on the space between the two coils.
Inductor in Series Combination
In this method, the current flowing through the two inductors is in the same direction.
As the current flowing in the same direction, the magnetic fluxes of self and mutual induction will end up linking with each other and add together.
Therefore, the total inductance can be calculated using the below formula-
Leq = L1 +L2 +2M
is the total equivalent inductance and M is the mutual inductance.
In such a case, the current flow through the inductors is in the opposite direction.
Therefore, the total inductance can be calculated using the below formula,
Leq = L1 +L2 - 2M
is the total equivalent inductance and M is the mutual inductance.
Inductors in Parallel Combination
, as seen on the left image, the dot convention clearly shows that the current flow through the inductors is in the same direction.
To calculate the total inductance, below formula can be very helpful.
In such a case, the self-induced electromagnetic field in two coils allows the mutually induced emf.
Leq = (L1L2 ᾠM2) / (L1 +L2 +2M)
, the inductors are connected in parallel with the opposite direction of each other.
In such a case, the mutual inductance creates a voltage which opposes the self-induced EMF.
The equivalent inductance of the parallel circuit can be calculated using the below formula-
Leq = (L1L2 ᾠM2) / (L1 +L2 +2M)
Fundamentals of Motors ᾠTheory and Laws to Design a Motor
This will help us understand the fundamentals behind a motor spinning.
and the next blog would be on motor control.
But there are certain topics which are necessary to understand before going into the depth of motor control and we will cover them in this article.
Operation of a Linear Motor
Types of Motors and its History
Saliency
Flux Interaction between the Stator and Rotor
Operation of a Linear Motor
We will spend some time understanding these laws.
Some of you might already know it but it is good to go through them once again.
You might learn something new.
Faraday’s law
Faraday’s Law of Induction states the relationship between the flux of a coil of wire and the voltage induced in it.
e(t) = -dφ/dt ‐
It can be described as the coil is formed of N single turns in a series configuration.
Thus,
λ = Nφ
e(t) = -dλ/dt = -Ndφ/dt
The minus sign is usually attributed to Lenz’s law.
: An EMF (electromotive force) is induced in a coil of wire if the flux linked with it changes.
The polarity of the EMF is such that if a resistor was shunted across it, the current flowing in it would oppose the change in flux which induced that EMF.
moves the rod horizontally but the rod is always in contact with the horizontal conductors.
The external resistor R is used as a shunt to allow the current to flow.
So, the arrangement acts like a simple electrical circuit with a voltage source (the induced EMF) and a resistor.
The flux linked with this loop is changing as the area linked with the B is increasing.
This induces an EMF in the circuit according to the Faraday’s Law (the magnitude is decided by how fast the flux is changing) and Lenz’s Law (the polarity is decided such that the current induced will oppose the change of flux).
If we curl our fingers in the direction of the induced current, then the thumb will give the direction of the generated field by that induced current.
In this case, to oppose the increasing flux due to B field, we need to develop a field a field out of the plane of the paper, and hence, the current will flow in a counter-clockwise direction.
As a result, terminal A is more positive than the terminal B.
From the load point of view, a positive EMF is developed with increasing flux and hence we will write the equation as
e(t) = d λ/dt
Observe that we have ignored the negative sign as we are writing this equation from the point of view of the load.
(A similar case will come up when we start dealing with motors).
The final electrical circuit will take the form as below figure.
Even though the discussed case is of a generator, we have used the sign convention from the motor point of view and the polarity shown in the figure below is correct.
(It will become obvious when we move on to the motor operation).
A coil of 1 turn (conductor in this case) will produce a flux linkage of:
Where A represents the area of the loop, l is the length of the conductor, v is the velocity with which the rod is moving because of the applied force.
But the external resistor will determine how much force is needed to maintain the velocity (and hence the current).
This discussion is continued forward in the form of Lorentz Law.
Lorentz Law
We will check out the equation first and then try to understand it.
F = q .
(E + Vc x B)
in an electromagnetic field, it experiences a force.
In a motor, the electric field E is irrelevant.
Thus,
F = q .
Vc .
B
If the field is constant with time over the length of the conductor and perpendicular to it, we can write the above equations as:
F = q .
dx/dt .
B = dq/dt .
x .
B = i.
l.
B = B.
i .
l
It shows that the force acting on the charge is directly proportional to the current.
All the energy is dissipated as heat in the resistor.
The law of conservation of energy should be satisfied and hence we get:
F .
v = e .
i
This equation represents how mechanical energy is converted to electrical energy.
This arrangement is called a linear generator.
) given by the Lorentz Law.
The direction of the force can be established by the Right-Hand Rule shown below
All the motors are derived from these basic principles.
There are many detailed articles and videos that you will find describing the operation of brushed DC motor, brushless motors, PMSM motors, Induction motors, etc.
So, it does not make sense making one more article describing the operation.
Here is the link to some of the good educational videos on different types of motors and its operation.
History of Motors
Historically, there have been three types of motors that have been widely used ᾠbrush commutator DC, synchronous and induction motors.
Many applications demand varying speed and DC motors were widely used.
But the introduction of thyristors around 1958 and the transistor technology changed the scene.
Inverters were developed which helped in an efficient speed control application.
The transistor devices could be turned on and off at will and it allowed PWM operation.
The basic control schemes that were developed earlier were V/f drives for induction machines.
In parallel, permanent magnets started replacing field coils to improve efficiency.
And the use of inverter along with sinusoidal permanent magnet machines allowed elimination of brushes to improve the life and reliability of the motor.
The next major step was in the control of these brushless machines.
The two-reaction theory (or d-q theory) was introduced by Andre Blondel in France before 1900.
It was combined with complex space vectors which allowed to model a machine accurately in transient and steady state.
For the first time, the electrical and mechanical quantities could be related to each other.
Induction motors did not see much changes until 1960.
Two Germans ᾠBlaschke and Hasse made some key innovations which led to the now famous vector control of induction motors.
Vector control deals with the transient model of the induction motor rather than the steady state.
Besides controlling the voltage amplitude to frequency ratio, it also controls the phase.
This helped the induction motor to be used in speed control and servo applications with high dynamics.
The sensorless algorithm was the next big step in control of these motors.
Vector control (or Field Oriented Control) requires to know the rotor position.
Expensive positions sensors were used earlier.
The ability to estimate the rotor position based on the motor model allowed the motors to run without any sensors.
There have been very few changes since then.
The motor design and its control more or less remain the same.
Motors have been evolving since the last century.
And electronics have helped them to be used in varying applications.
The majority of electricity used in this world is consumed by motors!
Different Types of Motors
The motors can be classified in a lot of different ways.
We will look at some of the classifications.
‘At its terminalsᾠis important because it eliminates what kind of electronics is used to run the motor.
For example: The brushless DC motor actually cannot run directly on DC supply and it requires an electronic circuit.
The motor can be classified based on power supply and based on commutation - brush or brushless, as shown below
Saliency
This will be the case with IPM (Interior Permanent Magnet) motors.
(There are motors that purely work on reluctance effect but we will not be discussing them here.) The next topic will help you to understand flux linkage and saliency much better.
(Note: Angle Advance in below figure refers to the phase difference between the stator current and air gap flux.)
Flux Interaction between the Rotor and the Stator
is approximately equal to 1).
The MMF (magnetomotive force) developed across the steel is very less as it has negligible reluctance compared to the air gap.
(An analog to the electrical circuit would be: A voltage source (magnet) drives current (flux) through a resistor (air gap reluctance).
The conductors (steel) connected to the resistor have very low resistance and we can ignore the voltage drop (MMF drop) across it).
Thus the structure of the stator and rotor steel has a negligible influence and the entire MMF is developed across the effective air gap reluctance (any non-ferrous material in the flux path is considered to have a relative permeability equal to that of air-gap).
The air gap length is negligible compared to the rotor diameter and it can be safely assumed that the flux from the rotor is perpendicular to the stator.
There are fringing effects and other non-linearities due to slots and teeth but these are generally ignored in modeling the machine.
(You CANNOT ignore them when designing the machine).
But the flux in the air gap is not just given by the rotor flux (magnets in case of permanent magnet machine).
The current in the stator coil also contributes to the flux.
It is the interaction of these 2 fluxes that will determine the torque acting on the motor.
And the term which describes it is called the effective air gap flux linkage.
The idea is not to go into mathematics and derive the equations but to take away two points:
We are concerned with only the flux in the air gap as the entire MMF is developed across it.
The effective flux linkage in the air gap is due to both the stator current and rotor flux (magnets) and the interaction between them produces torque.
perpendicular to it).
We will get back to the D and Q axis in future articles.
It is not important for the above question.
A,B,C ᾠnon-salient, D,E,F,G,H ᾠsalient (the magnets affect the reluctance in different rotor position, see below figure, in J,K- both the rotor and stator are non-salient.
We will end this article at this point.
A lot more mathematics and machine modeling could have been discussed but it would become too complex here.
We have covered most of the topics that are needed to understand the control of a motor.
The next series of articles will directly move to Field Oriented Control (FOC), Space Vector Modulation (SVM), Flux Weakening, and all the practical hardware and software aspects where you might possibly get stuck once you start designing the controller.
article/role-of-rf-power-semiconductor-in-ev-revolution-opportunities-and-challenges
The Staple Role of RF Power Semiconductor in EV Revolution - Opportunities & Challenges
Although the ever-increasing number of 5G roll-outs and climbing consumer electronic devices sales will predominantly create a favourable environment for the RF power semiconductor demand growth, automotive industry also remains among the key consumer areas of RF power modules.
).
to be met in 2025.
This scenario clearly prompts at the significant opportunities for highly efficient RF power semiconductors that would effectively function at elevated temperatures.
Manufacturers of RF power modules are thus constantly focusing their strategies on the development of products based on SiC (silicon carbide), GaN (gallium nitride), and WBG (wide band-gap) technologies.
GaN Emerging as a Choice of Material for RF Power Semiconductors
Despite a number of R&D efforts prevailing in the WBG semiconductor realm, the SiC variant has remained the traditional choice for EVs and HEVs, over the recent past.
However, on the other side, SiC has already arrived at the maturity stage in market and is being challenged by other competitor technologies that are gaining ground over it ᾠparticularly in case of power electronics and other demanding applications in electric and hybrid electric vehicles.
While EVs and HEVs typically utilize SiC based RF power semiconductors for regulation of DC/DC converters in the powertrain, the transition time tends to restrict their switching frequencies between 10 kHz and 100 kHz.
Currently, almost every automaker around the world is putting efforts in innovative around the GaN designs of RF power semiconductors.
Introduction of GaN semiconductor held the promise to potentially overcome this longstanding challenge by enabling switching time within the nanosecond range and operation at temperatures as high as 200°C.
The faster functionality of GaN semiconductor results on high switching frequency and thereby, low switching loss.
Moreover, the lower power electronic volume translates into reduced overall weight, which subsequently supports lightweight and more efficiency economy.
Several studies advocate de facto potential of GaN based semiconductor for high power conversion at high speed.
Moving to a new era of power electronics that would best complement the objective of EVs and HEVs, key attributes of GaN semiconductor materials, such as superior switching speed, high operating temperatures, lesser switching and conductivity losses, compact-sized packaging, and potential cost competitiveness, will continue to place GaN-based RF semiconductors over all other counterparts.
Potential Challenges Limiting Expanse of RF Power Semiconductor in EVs & HEVs
Despite all the innovations and positive outcomes entering markets, a few challenges still remain as the barriers to RF power semiconductor’s functionality in electric vehicles.
After all, driving a high-power component within nanoseconds is a complex chore and comes with multiple difficulties that are yet to be resolved.
One of the most prominent challenges is the improvement of voltage ratings.
Enhancing efficient operability at higher temperatures without altering conventional designs is another important challenge that continues to capture R&D interests in the RF semiconductor space.
The fact repeatedly highlights that applications of power electronic modules in EVs and HEVs are highly demanding and their performance relies not only on voltage- and performance-based innovations.
A constant push in terms of structural and design technology improvements ensure endurance, reliability, and thermal resistance of RF devices within hybrid and pure/battery electric vehicles.
Packaging challenges are capturing attention
While distortion of surrounding electronic parts has been another factor challenging suitability of RF semiconductor devices within EV designs, EMC (epoxy molding compound) semiconductor packaging has emerged as a highly lucrative area of research, as it allows operation without disturbing the neighboring electronic components.
are already being perceived as the mainstream of the near future, the designs still have a scope for improvement in terms of thermal management.
Leading companies in the RF semiconductor landscape are thus emphasizing widening their efforts related to packaging to achieve improved reliability for usage in electric vehicles.
Better future for WBG ᾠIs there any?
In the backdrop of SiC’s maturity and GaN’s proven superiority, the market is however failing to resolve the reliability concerns associated with WBG, which is eventually limiting market penetration of WBG type FR semiconductors in the long run.
The only way to achieve engineering of more robust WBG type semiconductors lies in deeper understanding of their failure mechanisms in harsh operational conditions.
Experts also opine that WBG might attain maturity in market without any concrete strategic support that would re-establish their reliability for further utilization.
What the Industry’s Behemoths are up to?
, the U.S.-based Cree Inc.
company specialized in premium SiC and GaN RF power products, recently launched a new product that brings about more than 75% reduction in the inverter losses of EV drivetrain.
With such improved efficiency, engineers are likely to discover new parameters to innovate in terms of battery usage, range, design, thermal management, and packaging.
The high-voltage circuitry of inverters in electric and hybrid electric vehicles generate a lot of heat and this problem needs to be addressed with efficient cooling mechanism.
Research has been recommending time and again that the reduction of size and weight of inverters is the key to attaining improved cooling of the automotive components in EVs and HEVs.
, for an instance) remain focused on inverter mass and size with the help of a double cooling technology that uses either liquid or air to directly cool the desired high-voltage RF power module.
Such a mechanism also allows adds to the compactness and flexibility of the overall design and thereby, to the efforts in reducing the power generation losses.
has particularly developed this ultra-compact RF power product for hybrid EVs and claims it to be the world’s smallest-ever SiC device of its kind.
The reduced packaging volume of this device consumes significantly lesser space in the vehicle interior and thus underpins higher fuel and energy efficiency.
The device’s commercialization is anticipated in the next couple of years.
Partly supported by the New Energy and Industrial Technology Development Organization (NEDO, Japan), the company will also commence with mass production of the ultra-compact SiC inverter, soon.
, based in France, with an objective to enable the existing EV and HEV technologies to achieve their maximum potential.
Silicon Mobility’s manufacturing partner in the development of FPCU is the US-based semiconductor manufacturer ᾠGlobalFoundries.
RF Power Semiconductor Demand to Surge in the Asia Pacific Region
of the total new vehicle sales will be accounted by EVs.
The latest data of the China Association of Automobile Manufacturers implies that over half a million EVs were sold in China alone, in the year 2016, which majorly included commercial vehicles and buses.
While China will remain the largest market for EVs in the long run, the rate of EV production has been on a constant high in the entire Asia Pacific region.
In addition to the significantly flourishing consumer electronics industry, the region has been witnessing considerable growth of the EVs market, recently, thereby creating a strong opportunity for the penetration of RF power semiconductors, preferably based on GaN.
The global valuation of RF power semiconductor market is roughly US$ 12 billion (as of 2018 end).
With breakthrough opportunities arising from the onset of 5G technology, extensive adoption of wireless network infrastructure and IIoT (Industrial Internet of Things) technology, prosperous outlook of the consumer electronics landscape, and growing electric vehicle (EV) sales, the RF power semiconductor market revenues are likely to expand at an impressive 12% compound annual growth rate through 2027.
article/what-is-an-inductor-construction-and-working
Understanding an Inductor and It's Working
and inductors.
Inductors are closely related to the capacitors as they both use an electric field to store energy and both are two terminal passive components.
But capacitors and Inductors have different construction properties, limitations and usage.
Inductor is a two terminal component which stores energy in its magnetic fields.
It is also referred as coil or choke.
It blocks any changes in current flowing through it.
If the current flow through an inductor is changed at the rate of one ampere per second and 1V of EMF is produced inside the coil, then the value of inductance will be 1 Henry.
In Electronics the inductor with a value of Henry is rarely used as it is a very high value in terms of the application.
Typically, much lower values like, Milli Henry, Micro Henry or Nano Henry are used in most of the applications.
Symbol
Value
Relation with Henry
mH
Milli Henry
1/1000
uH
Micro Henry
1/1000000
nH
Nano Henry
1/1000000000
is shown in the below image-
The symbol is a representation of twisted wires which means wires are constructed to become a coil.
Construction of Inductor
Inductors are formed using insulated copper wires which further formed as a coil.
The coil can be different in shapes & sizes and also can be wrapped in a different type of materials.
The inductance of an Inductor is highly dependable on multiple factors, such as number of turns of wire, the spacing between the turns, no of layers of turns, type of core materials, its magnetic permeability, size, shape etc.
There is a huge difference between Ideal Inductor and the actual real inductors used in electronic circuitry.
Real inductor not only has inductance, but it also has capacitance and resistance.
The closely wrapped coils produce a measurable amount of stray capacitance between coil turns.
This additional capacitance, as well as wire resistance, alters the high-frequency behaviors of an inductor.
Inductors are used in almost every electronic product, some DIY applications of inductor are:
Metal DetectorArduino Metal DetectorFM transmitterOscillators
How does an Inductor work?
.
So, as of now, there is a magnetic field across inductors, produced by the current flowing through it.
, the generated EMF is proportional to the rate of change of the magnetic flux.
VL = N (dΦ / dt)
Construction of an Inductor
When the current flow through the wire, the electromagnetic field will develop across the conductor and electromotive force or EMF will generate depending upon the rate of change of the magnetic flux.
So, the flux linkage will be N.
is said to be
μN2A / L
where N is the number of turns
A is the cross sectional area of the core material
L is the length of the coil
μ is the permeability of the core material which is a constant.
is
Vemf(L) = -L (di / dt)
where di/dt is the rate of current change
L is the self-inductance.
The induced EMF direction will be opposite of the applied current source.
:
LC Meter using Arduino: Measuring Inductance and FrequencyHow to measure value of Inductor or Capacitor using Oscilloscope ᾠResonant Frequency Method
Why an Inductor blocks AC rather than DC?
It is quite interesting.
To understand this, one needs to understand the Lenz law.
As per the Lenz law, the direction of current induced in a conductor due to the change in magnetic field is such that it creates a magnetic field that opposes the change that produced it.
So, there are two types of applications.
First is to apply DC across the inductor and the other one is to apply AC across the inductor.
, the AC changes the current flow which is opposed by the inductor by increasing the reactance.
The higher the frequency of AC, the higher the rate of change current and the higher the blocking effect from the inductor.
, the inductor act as a near short circuit with very low resistance.
In a steady state DC flow, the rate of current changes is zero which further make the di/dt zero.
So, there was no voltage is induced and the Inductor do not oppose the flow of DC.
?
Let's considered the below circuit.
or any kind of typical switch which will provide the voltage source to the inductor.
.
the current from the voltage source to the inductor start rising until the current flow reaches the maximum steady state value.
In this time the current flow through the inductor increases and the rate of current change depends on the value of inductance.
As per Faraday's law, the inductor generates back EMF which stays until the DC gets into the stable state.
During the steady state there is no current change in the coil and current simply pass through the coil.
During this time, an ideal inductor will act as a short circuit as it has no resistance, but in a practical situation, the current flow through the coil and the coil has a resistance as well as the capacitance.
On the other state when switch is being closed again, the Inductor current goes down rapidly and again there is change is current which further leads to EMF generation.
Current and Voltage in an Inductor
where P = Voltage x Current.
Therefore, in such a case, the voltage is –L (di / dt) and the current is i.
So, the power in an Inductor can be calculated using this formula
PL = L (di / dt) i
But during the steady state the real Inductor is just act like a resistor.
So the power can be calculated as
P = V2R
An Inductor stores energy using the magnetic field.
The energy stored in the Inductor can be calculated using this formula-
W(t) = Li2(t) / 2
There are different types of Inductors available in terms of their construction and size.
Construction wise Inductors can be formed in air core, ferrite core, iron core etc and Shape-wise there are different types of Inductors available, like the drum core type, choke type, transformer type etc.
Applications of Inductors
Inductors are used in a wide area of application.
In RF related application.
SMPS and Power supplies.
In Transformer.
Surge protector to limit inrush current.
Inside the Mechanical Relays etc.
article/energy-saving-quad-low-side-intelligent-power-switches
Energy Saving Quad Low Side Intelligent Power Switches
In this paper we present the new quad low side intelligent power switches specifically designed to minimize total power dissipation; thanks to its low Rds(on) per channel and unique in the market the programmable output current limitation and programmable cut-off delay time.
Main features of the device, together with applications highlights -based on the company reference board specifically developed- are here reported.
I.
Introduction
up to 100kHz, quad low side switches able to drive any type of load (resistive, inductive and capacitive) with one side connected to supply voltage (Vcc).
The device is named IPS4260L, it has integrated on chip four 45V Power MOSFETs channels (260mW typical Rds(on) at 25 degrees Celsius) together with logic, driver, protections and diagnostic.
The IPS4260L has been housed in the tiny Jedec standard HTSSOP 20 leads power package.
The device is made by using the STMicroelectronics Multipower-BCD technology; this is a STMicroelectronics Smart Power technology that allows the integration in the same chip both of the control part and of the power stage.
II.
IPS4260L BLOCK DIAGRAM
The block diagram of the device is shown in figure 1.
connect between ILIM pin and SGND), inductive clamp (typically 58V) and supply rail wire break protection.
Thanks to current limitation, cut-off time and thermal protections, each channel is self protected against load short-circuit and over-current.
Due to the clamping chain at 58V it is realized a demagnetization circuitry; the device is indeed able to manage big inductive loads, discharging the inductive energy in fast way.
If the inductive load is very big you have to connect a Zener or TVS diode between VZ pin and GND or Supply rail to discharge the load in fast way (see figure below) or have to connect the Vz pin to supply rail to discharge it in slow way.
Under-voltage protection avoids abnormal operations with very low supply voltages, while loss of ground protection switch-OFF the Power stages a soon as the ground references lost for any reason; thus avoiding the device destruction.
C; it protects the channel in case of a generic over-load.
The input blocks of the device are input/output.
They are TTL/CMOS compatible and designed in order to minimize input switching times, and to allow the connection of an optocoupler through a series resistor.
The channels are switched ON with a minimum level input voltage > 2.0V.
When the channel is in cut-off or thermal shutdown the relevant input pin is internal switched OFF through the open drain transistor.
Open drain common status pins are able to drive directly a light emitting diode (LED), they give indications of both cut-off protection or junction over-temperature shut-down (FLT pin) and open load in OFF state or short to GND (OL pin).
III.
NON-DISSIPATIVE SHORT CIRCUIT
As before mentioned the IPS4260L device has a current limitation protection integrated settable using an external resistor.
Together with the junction thermal protection and detection, included on each channel, the IPS4260L has also integrated what is called “non-dissipative short circuit blockᾬ which is intended to limit dissipation of the device as a whole.
This further protection avoids the PCB degradation in case of large number of channels in over-load conditions, due to the quick increase of device temperature.
(junction shutdown temperature).
represent the voltage applied to the INx pin, it goes down every time the FLT pin go down while the MCUx voltage stay constant.
(reset temperature).
What is important to highlight is that the thermal protection acts only on the over-load channel; non over-loaded channel continue to operate normally.
IV.
OPEN LOAD DETECTION IN OFF STATE
In order to detect the open load fault in OFF state a pull-down resistor have to connect between the PGND line and the output pin (see Figure 5).
In a normal condition, the current flows through the network made up of the pull-down resistor and the load.
The voltage across the load is less than the minimum open load voltage, so the OL pin is kept high level.
), to reduce a noise interference.
After this time the OL pin goes low to level, thus signalizing the open load.
In fig.
6 we show the waveforms of the generic Input pin voltage, the relevant Output voltage and the OL pin voltage when an open load event occurs and when it finish.
time (Typ.
16.5 ms).
V.
REFERENCE BOARD AND APPLICATION TESTS
In figure 9 a typical application circuit of the device IPS4260L is reported; it represents the output stage of a programmable logic controller designed for industrial automation or process control.
We offer an User Manual and a dedicate graphical user interface (GUI) to drive it.
In order to protect the device in low-side configuration from the harsh industrial conditions of power supply lines, usually optocouplers diodes are used to separate the application control
circuits from the power supply, as well in the inputs as in the diagnostic pins.
Transil diodes protect the Low Side Switch (LSS) against both positive and negative surge pulses to make the device compliant with IEC 61000-4-5.
An electrolytic capacitor must be placed on the bus line (Vcc) in order to filter bus inductance effect making supply voltage stable and avoiding under voltage shut-down.
The size of the electrolytic capacitor is selected based on the slope of the output current, the impedance of the complex power supply cables, as well as the maximum allowed voltage drop across the device.
A low ESR capacitor is suggested, as close as possible to the LSS, in order to filter the power supply line for electromagnetic compatibility concerns.
In our example a 47uF capacitor has been selected.
The toughest loads can be driven in factory automation/process control are the inductive ones; it is a common case to drive 1.15 Henry nominal load.
The associated energy to manage such inductive loads is very appreciable, carrying out a sensible power dissipation and a very high junction temperature: IPS4260L was just designed to drive such a big loads using an external Zener or TVS diode connects between VZ pin and GND or Supply rail to discharge the load in fast way (see figure 2) or have to connect the Vz pin to supply rail to discharge it in slow way.
Over-current and short circuit of the load to the supply voltage are the harshest events we must face during the digital output operation.
In these bad events, the output stages must survive dissipating all the associated energy.
Besides the loads, connected to the output stages, must be protected from the peak of current that could reach unexpected values.
In order to safely manage very high peaks of currents during short circuit of outputs to the supply voltage a current limitation block is integrated on chip.
As result only a current spike for a short time is allowed; just the time needed to intervene the current limitation circuitry, so trimming the maximum output current using an external resistor.
It is the same during a hard over-load.
Internally limited output current is not enough however; in fact, if short circuit or over-load duration last during the time, the power dissipated into the device as well as into the load, become important so causing an over-heating able to destroy the device and/or the load involved.
) connected between CoD pin and SGND ground plane.
After this time the channels rest in OFF for a time, named power stage restart delay time (tres), to avoid the PCB degradation in case of large number of channels in over-load conditions and to reduce the energy that flows in both device and loads.
) the junction thermal protection blocks, one for each channel, switch OFF the channels.
They restart only when Tj come back below the reset threshold.
It is possible to disable the “non-dissipative short circuit blockᾠconnecting the CoD pin in short with SGND ground plane, thus only the junction thermal protection is active into the IPS4260L.
) during short circuit conditions; as you can see in both figures the output current, after a short peak, is limited at a fixed value.
In figure 9, in addition, we report the output voltage of the relevant channel and the input voltage that follow the waveform of fault voltage because the input pins of the IPS4260L are used for diagnostic purpose.
and the cycle begin again.
Behavior with capacitive load
you can see the “non-dissipative short circuit protectionᾠintervention, so that the power output loaded is switched OFF as well as per over-load or short circuit.
When the capacitor is almost completely charged the current goes below the set current limiting: this is clearly shown in figure 13 where you can observe in the middle of the blue color waveform a sudden change of slope in the charging current until reaching zero value (capacitor completely charged).
When the output capacitor is charged and you give a low voltage to the input the OL pin behavior corresponds to the short to GND case, because of the voltage on it.
This means that in OFF state (input voltage low) the diagnostic signal of OL pin (normally high) goes low (see truth table at figure 12).
VI.
Conclusion
A smart monolithic quad low side switches has been presented.
The new intelligent power switch (IPS) provides improved accuracy to minimize energy losses and prevent system errors when faults occur.
These advantages are achieved using ST’s latest generation Multipower-BCD technology, which allows a programmable over-load current limit to maintain stable power conditions while the system is recovering.
By providing an integrated solution for four output channels, the IPS4260L also simplifies design, enhances reliability, and saves pc-board space.
This new quad-channel IC is an important addition to ST’s portfolio of industrial IPS, which already includes single, dual, quad and octal-channels high side devices.
References
.
About the Author
Senior Technical Marketing Engineer
Intelligent Power Switches (IPS) & IO-Link products
Industrial & Power Conversion Division
STMicroelectronics
article/innovations-in-supercapacitor-development-past-present-and-future
Innovations in Supercapacitor Development: Past, Present, and the Future
, triggered by the essentiality of faster storage, efficient power management, and energy optimization.
- also known as ultracapacitors or electrochemical capacitors (ECs).
Focus on Efficient Power Storage Triggered the Emergence of Supercapacitors
As industrial developments started revolving around the electrification trend, innovations in the designs of supercapacitors picked up the pace.
Global giants, including General Electric, conducted experiments dedicated toward design improvements in supercapacitors, in a bid to capitalize on the growing demand for supercapacitors in industries as a key electrification enabler.
The NEC Corporation was among the first few companies to commercially introduce supercapacitors to the world; the Standard Oil Company of Ohio (SOHIO) is mainly attributed for the invention.
Post the emergence of superconductors as a more efficient energy storage solution, the popularity of the EC technology surged instantly.
The designs of supercapacitors have advanced through several generations ever since their first commercial launch.
Research organizations and leading companies in the power electronics industry are still focusing on innovating around the manufacturing methods and materials to further improve the cost-efficiency and performance of supercapacitors.
Research Institutes Discovered Innovative Manufacturing Procedures for Supercapacitors
Also, durability-related concerns apropos of supercapacitors has been restricting its adoption in industrial applications to a certain extent.
In response to these concerns, supercapacitor manufacturing companies have been investing heavily in research and development (R&D) to design a more superior version of supercapacitors.
In February 2013, researchers at University of California, Los Angeles discovered a groundbreaking and cost-effective fabrication method to manufacture micro-scale supercapacitors by using a consumer-grade LightScribe DVD burner.
These micro-supercapacitors consist of a one-atom–thick layer of graphitic carbon and can be easily integrated into miniaturized electronic devices.
With the use a two-dimensional sheet of graphene in combination with the new fabrication technique, researchers could reduce the manufacturing costs to a great extent and expanding the applications scope for supercapacitors.
In July 2013, Researchers from Ulsan National Institute of Science and Technology (UNIST) developed an innovative method to mass produce 3-dimensional mesoporous graphene nano-ball (MGB) that can be used in the manufacturing of supercapacitors.
The researchers projected that the properties of mesoporous graphene will improve the scalability, quality, and cost-efficiency of supercapacitors, expanding the scope of their applications in electric vehicles.
In August 2014, engineers at Monash University in Australia developed a novel method of method of producing the graphene inside supercapacitors to improve their energy density 10 times more than commercial devices.
The engineers created a macroscopic graphene materialthrough a process similar to traditional paper manufacturing method.
In addition, they further affirmed that by reducing the solution-based chemical ᾠgraphite oxide in graphene, the engineers could open new avenues for commercialization of graphene and 10x energy denser supercapacitors.
A group of researchers in South Korea discovered an unusually innovative yet highly suitable alternative material for supercapacitor electrodes in August 2014.
They devised a way to use cigarette filters in supercapacitors, which can be transformed into a high-performing carbon-based material with high power densities.
Researchers could successfully use used-cigarette filters to store more electrical energy than commercially available carbon.
The Focus on Supercapacitor Material Developments Ubiquitous
The move towards the development of high-performance materials has gained utter palpability among the supercapacitor manufacturers, with the ever-growing demand for supercapacitors in various industrial applications, such as wearable consumer electronics and electric vehicles.
Though graphene remains one of the apt materials for supercapacitors, ongoing research activities allude significant transformations in the supercapacitor market’s landscape.
while conducting the experiments for their fuel cells project.
The researchers found that the highly-porous supercapacitor material is low-cost, light, and non-toxic, and can be used in potential commercial applications of supercapacitors, such as transportation, electronics, and energy storage devices.
to reduce thicknesses on the order of millimeters and improve performance characteristics of supercapacitors including power densities and capacitance retention.
was made out of ordinary paper by engineers from Georgia Tech and Korea University that could store more energy for longer, especially in wearable electronic products as it is flexible.
Scientists, engineers, and researchers around the world are mainly focusing on balancing the power density and energy density of supercapacitors in order to avoid loss of power at once.
Recent developments and innovations in the materials used in supercapacitors manufacturing mainly center on reducing the possibility of self-discharge or short circuit.
Stakeholders in the supercapacitor market are aiming to capitalize on various performance characteristics of pseudo-capacitors and hybrid capacitors, which can reflect higher energy density than any other types of supercapacitors.
While the demand for electrical double layer capacitors remain highest across the supercapacitors market, hybrid capacitors are witnessing an upsurge in demand in various industrial applications.
Automotive Industry ᾠKey Growth Potential Area for Supercapacitor Manufacturers
of the revenue share of supercapacitors market.
However, with the recent developments in automotive industry, automobiles have become one of the most important applications of supercapacitors.
have foreseen to be promising.
This has led the supercapacitor manufacturers to eye profitable opportunities in the rapidly-evolving automotive industry.
is one of the most important business strategies of supercapacitor manufacturing companies.
On the other hand, automotive manufacturers are also in the race to roll out most efficient electric vehicles, which justified their hunt for high-quality energy storage systems.
This ultimately reflects in the ever-expanding scope for innovations in supercapacitors in the rapidly-evolving automotive industry.
ᾠglobal giant in the automotive and energy industries ᾠannounced that it has acquired Maxwell Technologies Inc.
ᾠa leading battery technology company ᾠfor approximately US$ 218 million.
The company aims to capitalize on lucrative opportunities for electric vehicles, and with this acquisition, it plans to add expertise in the field of supercapacitors that could speed up car charging capabilities.
ᾠworld’s leading luxury car maker ᾠentered a collaboration agreement with Superdielectrics Ltd ᾠa UK-based technology start-up, explore the potential of supercapacitors and create a state-of-the-art high-energy storage technology.
With this partnership, Roll-Royce aims to combine its expertise in material science with Superdielectricsᾠhydrophilic polymers for developing world-class supercapacitor battery applications.
is another leading automaker to join the pack of automobile companies that are planning to leverage supercapacitorsᾠextraordinary characteristics during the electrification of the automotive industry.
The company’s chief technical officer recently declared that the company has previously used supercapacitors in the Lamborghini Aventador for the starter battery.
Experts predicts that Aventador’s successor might use the identical supercapacitors.
The quest for constant advancements in supercapacitorsᾠperformance is likely to trigger some groundbreaking innovations in the supercapacitors market in coming years.
Role of Supercapacitors in Prospects of Electronics and Energy & Power Industries
Automotive and transportation industry is expected to account for more than one third of the revenue share of the supercapacitors market in the coming decade.
Despite the glorified future for supercapacitors in the new-age automotive industry, consumer electronics and energy & power industries are likely to hold a lion’s share in development of the supercapacitors market.
Supercapacitors are touted as the workhorse of any electronic product that works on batteries or energy storage systems.
In the coming years, supercapacitors are likely to witness ubiquitous acceptance in various industry verticals.
The future of supercapacitors market is likely to witness the emergence of ECs that will power the future of modern wearables and consumer electronic products.
Solar supercapacitors are also a thing from future, which is expected to have a huge sales potentials in the wearable sensors landscape, especially in wearable health devices.
in the near future.
With increasing applications of supercapacitors in various industrial sectors, such as electronics, energy & power, military & defense, and aerospace, the global market for supercapacitors is expected to surpass US$ 5.5 billion by 2028.
The exponential growth rate of the supercapacitors market is expected to amplify lucrative opportunities for researchers, manufacturers, and other stakeholders in the landscape.
tutorial/real-life-object-detection-using-opencv-python-detecting-objects-in-live-video
Real Life Object Detection using OpenCV ᾠDetecting objects in Live Video
, so if it recognizes the object it would mention objet found.
In the code the main part is played by the function which is called as SIFT detector, most of the processing is done by this function.
And in the other half of the code, we are starting with opening the webcam stream, then load the image template, i.e.
the reference image, that is the programme is actually looking through the webcam stream.
loop, and then capturing the corresponding height and width of the webcam frame, and after then define the parameters of the region of interest (ROI) box in which our object can fit in by taking the corresponding height and width of the webcam frame.
And then we draw the rectangle from the ROI parameters that we had defined above.
Then finally crop the rectangle out and feed it into the SWIFT detector part of the code.
Now the SIFT detector basically have two inputs, one is the cropped image and the other is the image template that we previously defined and then it gives us some matches, so matches are basically the number of objects or keypoints which are similar in the cropped image and the target image.
Then we define a threshold value for the matches, if the matches value is greater than the threshold, we put image found on our screen with green color of ROI rectangle.
Now let’s move back to the main part of the code, the function which is called as SIFT detector, it takes the input as two images one is the image where it is looking for the object and other is the object which we are trying to match to (image template).
Then gray scale the first image and define the image template as second image.
Then we create a SIFT detector object and run the OpenCV SIFT detect and compute function, so as to detect the keypoints and compute the descriptors, descriptors are basically the vectors which stores the information about the keypoints, and it’s really important as we do the matching between the descriptors of the images.
to zero and then we set the index and search parameters in the dictionary format, we just define the algorithm we are going to use which is KDTREE, and the number of trees we are going to use, the more tree we use the more complicated it gets and slower.
And in search parameter define the number of checks, which is basically number of matches it’s going to complete.
And then create our FLANN based matcher object by loading the parameter we previously defined which are index parameters and search parameters and based upon this create our FLANN based matcher, which is a KNN matcher where KNN is K-nearest neighbors, basically it’s a way where we look for nearest matchers and descriptors and we do the matching with initialization constant k.
Now this FLANN based matcher returns the number of matches we get.
FLANN based matching is just an approximation, so as to increase the accuracy of the FLANN based matcher we perform a Lowe’s ratio test and what it does is it looks for the matches from the knn flann based matcher and define some matric parameters which is distance here, for which distance is a numpy function, and once it meets the criteria append the matches to the good matches and returns the good matches found, and so the live video stream tells the number of matches found at the corner of the screen.
Now Let’s look at the code for the above description:
import cv2
import numpy as np
def sift_detector(new_image, image_template):
# Function that compares input image to template
# It then returns the number of SIFT matches between them
image1 = cv2.cvtColor(new_image, cv2.COLOR_BGR2GRAY)
image2 = image_template
# Create SIFT detector object
#sift = cv2.SIFT()
sift = cv2.xfeatures2d.SIFT_create()
# Obtain the keypoints and descriptors using SIFT
keypoints_1, descriptors_1 = sift.detectAndCompute(image1, None)
keypoints_2, descriptors_2 = sift.detectAndCompute(image2, None)
# Define parameters for our Flann Matcher
FLANN_INDEX_KDTREE = 0
index_params = dict(algorithm = FLANN_INDEX_KDTREE, trees = 3)
search_params = dict(checks = 100)
# Create the Flann Matcher object
flann = cv2.FlannBasedMatcher(index_params, search_params)
# Obtain matches using K-Nearest Neighbor Method
# the result 'matchs' is the number of similar matches found in both images
matches = flann.knnMatch(descriptors_1, descriptors_2, k=2)
# Store good matches using Lowe's ratio test
good_matches = []
for m,n in matches:
if m.distance < 0.7 * n.distance:
good_matches.append(m)
return len(good_matches)
cap = cv2.VideoCapture(0)
# Load our image template, this is our reference image
image_template = cv2.imread('phone.jpg', 0)
while True:
# Get webcam images
ret, frame = cap.read()
# Get height and width of webcam frame
height, width = frame.shape[:2]
# Define ROI Box Dimensions
top_left_x = int (width / 3)
top_left_y = int ((height / 2) + (height / 4))
bottom_right_x = int ((width / 3) * 2)
bottom_right_y = int ((height / 2) - (height / 4))
# Draw rectangular window for our region of interest
cv2.rectangle(frame, (top_left_x,top_left_y), (bottom_right_x,bottom_right_y), 255, 3)
# Crop window of observation we defined above
cropped = frame[bottom_right_y:top_left_y , top_left_x:bottom_right_x]
# Flip frame orientation horizontally
frame = cv2.flip(frame,1)
# Get number of SIFT matches
matches = sift_detector(cropped, image_template)
# Display status string showing the current no.
of matches
cv2.putText(frame,str(matches),(450,450), cv2.FONT_HERSHEY_COMPLEX, 2,(0,255,0),1)
# Our threshold to indicate object deteciton
# We use 10 since the SIFT detector returns little false positves
threshold = 10
# If matches exceed our threshold then object has been detected
if matches > threshold:
cv2.rectangle(frame, (top_left_x,top_left_y), (bottom_right_x,bottom_right_y), (0,255,0), 3)
cv2.putText(frame,'Object Found',(50,50), cv2.FONT_HERSHEY_COMPLEX, 2 ,(0,255,0), 2)
cv2.imshow('Object Detector using SIFT', frame)
if cv2.waitKey(1) == 13: #13 is the Enter Key
break
cap.release()
cv2.destroyAllWindows()
Object detection using ORB
Object detection using SIFT is pretty much cool and accurate, since it generates a much accurate number of matches based on keypoints, however its patented and that makes it hard for using it for the commercial applications, the other way out for that is the ORB algorithm for object detection.
Similar to the method of object detection by SIFT in which we divided the programme into two parts, the same will be followed here.
function is NONE, it is asking for the use of image mask or not and we are denying it here.
and inside BFMatcher we define two parameters one is NORM_HAMMING and other is the crossCheck whose value is TRUE.
Then compute the matches the matches between those two images using the descriptors defined above, which in all returns the number of matches since these matches are not approximation and hence there is no need to do Lowe’s ratio test, instead we sort the matches based upon distance, least the distance more the match is better (here the distance means distance between the points), and at the end we return the number of matches using length function.
Now let’s look at code for ORB based detection
import cv2
import numpy as np
def ORB_detector(new_image, image_template):
# Function that compares input image to template
# It then returns the number of ORB matches between them
image1 = cv2.cvtColor(new_image, cv2.COLOR_BGR2GRAY)
# Create ORB detector with 1000 keypoints with a scaling pyramid factor of 1.2
orb = cv2.ORB_create(1000, 1.2)
# Detect keypoints of original image
(kp1, des1) = orb.detectAndCompute(image1, None)
# Detect keypoints of rotated image
(kp2, des2) = orb.detectAndCompute(image_template, None)
# Create matcher
# Note we're no longer using Flannbased matching
bf = cv2.BFMatcher(cv2.NORM_HAMMING, crossCheck=True)
# Do matching
matches = bf.match(des1,des2)
# Sort the matches based on distance.
Least distance
# is better
matches = sorted(matches, key=lambda val: val.distance)
return len(matches)
cap = cv2.VideoCapture(0)
# Load our image template, this is our reference image
image_template = cv2.imread('phone.jpg', 0)
# image_template = cv2.imread('images/kitkat.jpg', 0)
while True:
# Get webcam images
ret, frame = cap.read()
# Get height and width of webcam frame
height, width = frame.shape[:2]
# Define ROI Box Dimensions (Note some of these things should be outside the loop)
top_left_x = int(width / 3)
top_left_y = int((height / 2) + (height / 4))
bottom_right_x = int((width / 3) * 2)
bottom_right_y = int((height / 2) - (height / 4))
# Draw rectangular window for our region of interest
cv2.rectangle(frame, (top_left_x,top_left_y), (bottom_right_x,bottom_right_y), 255, 3)
# Crop window of observation we defined above
cropped = frame[bottom_right_y:top_left_y , top_left_x:bottom_right_x]
# Flip frame orientation horizontally
frame = cv2.flip(frame,1)
# Get number of ORB matches
matches = ORB_detector(cropped, image_template)
# Display status string showing the current no.
of matches
output_string = "Matches = " + str(matches)
cv2.putText(frame, output_string, (50,450), cv2.FONT_HERSHEY_COMPLEX, 2, (250,0,150), 2)
# Our threshold to indicate object deteciton
# For new images or lightening conditions you may need to experiment a bit
# Note: The ORB detector to get the top 1000 matches, 350 is essentially a min 35% match
threshold = 250
# If matches exceed our threshold then object has been detected
if matches > threshold:
cv2.rectangle(frame, (top_left_x,top_left_y), (bottom_right_x,bottom_right_y), (0,255,0), 3)
cv2.putText(frame,'Object Found',(50,50), cv2.FONT_HERSHEY_COMPLEX, 2 ,(0,255,0), 2)
cv2.imshow('Object Detector using ORB', frame)
if cv2.waitKey(1) == 13: #13 is the Enter Key
break
cap.release()
cv2.destroyAllWindows()
Histogram of Oriented Gradients (HOG’s)
Now let’s talk about a different descriptor which is Histogram of Oriented Gradients (HOG’s).
It’s computed by a sliding window detector over an image, where a HOG descriptor is a computed for each position.
And then each position is combined for a single feature vector.
Like SIFT the scale of the image is adjusted by pyramiding.
where each HOG descriptor that is computed is fed to a SVM classifier to determine if the object was found or not.
Here’s the link to a Great Paper by Dalal & Triggs on using HOGs for Human Detection:
https://lear.inrialpes.fr/people/triggs/pubs/Dalal-cvpr05.pdf
Histogram of Oriented Gradients (HOG’s), Step by Step:
Understanding HOG’s could be quite complex, but here we are only going to deal with the theory of HOG’s without going deeper into the mathematics related to it.
, and on the upper corner is 8x8 pixel box here, so in this box we compute the gradient vector or edge orientations at each pixel.
So it means in this box we calculate the image gradient vector of pixels inside the box (they are sort of direction or flow of the image intensity itself), and this generates 64 (8 x 8) gradient vectors which are then represented as a histogram.
So imagine a histogram which represents each gradient vector.
So if all the points or intensities lied in one direction, the histogram for that direction let’s say 45 degrees, the histogram would have peak at 45 degrees.
So what we do now is we split each cell into angular bins, where each bin corresponds to a gradient direction (e.g.
x, y).
In the Dalal and Triggs paper, they used 9 bins0-180° (20° each bin).
This effectively reduces 64 vectors to just 9 values.
So what we have done is reduced the size but kept all the key information which is needed.
, we normalize the gradients to ensure invariance to illumination changes i.e.
Brightness and Contrast.
In this image, the intensity values are shown in the square according to the respective direction and all have difference of 50 between each other
H = 50, v = 50; ╢= ↵02+50 = 70.72, 70.72/100=0.707
We divide the vectors by the gradient magnitudes we get 0.707 for all, this is normalization.
Similarly, if we change the intensity or change the contrast we get the below values.
H = 50, v = 50; ╢= ↵02+50 = 70.72, 70.72/100=0.707; H = 100, v = 100; ╢= ↱002+100 =141.42, 141.42/100=1.41
, so here the blocks are basically a group of 4 cells, this takes into account neighboring blocks so normalize while taking into consideration larger segments of the image.
Now let’s look at the code
import numpy as np
import cv2
import matplotlib.pyplot as plt
# Load image then grayscale
image = cv2.imread('elephant.jpg')
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
# Show original Image
cv2.imshow('Input Image', image)
cv2.waitKey(0)
#defining the parameters, cell size and block size
# h x w in pixels
cell_size = (8, 8)
# h x w in cells
block_size = (2, 2)
# number of orientation bins
nbins = 9
# Using OpenCV's HOG Descriptor
# winSize is the size of the image cropped to a multiple of the cell size
hog = cv2.HOGDescriptor(_winSize=(gray.shape[1] // cell_size[1] * cell_size[1],
gray.shape[0] // cell_size[0] * cell_size[0]),
_blockSize=(block_size[1] * cell_size[1],
block_size[0] * cell_size[0]),
_blockStride=(cell_size[1], cell_size[0]),
_cellSize=(cell_size[1], cell_size[0]),
_nbins=nbins)
# Create numpy array shape which we use to create hog_features
n_cells = (gray.shape[0] // cell_size[0], gray.shape[1] // cell_size[1])
# We index blocks by rows first.
# hog_feats now contains the gradient amplitudes for each direction,
# for each cell of its group for each group.
Indexing is by rows then columns.
hog_feats = hog.compute(gray).reshape(n_cells[1] - block_size[1] + 1,
n_cells[0] - block_size[0] + 1,
block_size[0], block_size[1], nbins).transpose((1, 0, 2, 3, 4))
# Create our gradients array with nbin dimensions to store gradient orientations
gradients = np.zeros((n_cells[0], n_cells[1], nbins))
# Create array of dimensions
cell_count = np.full((n_cells[0], n_cells[1], 1), 0, dtype=int)
# Block Normalization
for off_y in range(block_size[0]):
for off_x in range(block_size[1]):
gradients[off_y:n_cells[0] - block_size[0] + off_y + 1,
off_x:n_cells[1] - block_size[1] + off_x + 1] += \
hog_feats[:, :, off_y, off_x, :]
cell_count[off_y:n_cells[0] - block_size[0] + off_y + 1,
off_x:n_cells[1] - block_size[1] + off_x + 1] += 1
# Average gradients
gradients /= cell_count
# Plot HOGs using Matplotlib
# angle is 360 / nbins * direction
color_bins = 5
plt.pcolor(gradients[:, :, color_bins])
plt.gca().invert_yaxis()
plt.gca().set_aspect('equal', adjustable='box')
plt.colorbar()
plt.show()
cv2.destroyAllWindows()
The image shows how the input image is represented as HOG representation.
HAAR cascade classifiers
As previously discussed, we can extract features from an image and use those features to classify or detect objects.
An object detection method that inputs Haar features into a series of classifiers (cascade) to identify objects in an image.
They are trained to identify one type of object, however, we can use several of them in parallel e.g.
detecting eyes and faces together.
(i.e.
images with the object present) and
negative images (i.e.
images without the object present).
However, this is a ridiculous number of calculations, even for a base window of 24 x 24 pixels (180,000 features generated).
and it found most informative features in the image.
Boosting is the process by which we use weak classifiers to build strong classifiers, simply by assigning heavier weighted penalties on incorrect classifications.
Reducing the 180,000 features to 6000, which is still quite a bit features.
- for face detection, the Viola Jones method used 38 stages.
Face & Eye detection
, xml stands for extensible markup language, this language is used to store vast amount of data, you could even build a database on it.
Just extract the zip file to get the xml file.
import numpy as np
import cv2
# We point OpenCV's CascadeClassifier function to where our
# classifier (XML file format) is stored, remember to keep the code and classifier in the same folder
face_cascade= cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
# Load our image then convert it to grayscale
image = cv2.imread('Trump.jpg')
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
# Our classifier returns the ROI of the detected face as a tuple
# It stores the top left coordinate and the bottom right coordinates
# it returns the list of lists, which are the location of different faces detected.
faces = face_cascade.detectMultiScale(gray, 1.3, 5)
# When no faces detected, face_classifier returns and empty tuple
if faces is ():
print("No faces found")
# We iterate through our faces array and draw a rectangle
# over each face in faces
for (x,y,w,h) in faces:
cv2.rectangle(image, (x,y), (x+w,y+h), (127,0,255), 2)
cv2.imshow('Face Detection', image)
cv2.waitKey(0)
cv2.destroyAllWindows()
import numpy as np
import cv2
face_classifier = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
eye_classifier = cv2.CascadeClassifier('haarcascade_eye.xml')
img = cv2.imread('Trump.jpg')
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
faces = face_classifier.detectMultiScale(gray, 1.3, 5)
# When no faces detected, face_classifier returns and empty tuple
if faces is ():
print("No Face Found")
for (x,y,w,h) in faces:
cv2.rectangle(img,(x,y),(x+w,y+h),(127,0,255),2)
cv2.imshow('img',img)
roi_gray = gray[y:y+h, x:x+w]
roi_color = img[y:y+h, x:x+w]
eyes = eye_classifier.detectMultiScale(roi_gray)
cv2.waitKey(0)
for (ex,ey,ew,eh) in eyes:
cv2.rectangle(roi_color,(ex,ey),(ex+ew,ey+eh),(255,255,0),2)
cv2.imshow('img',img)
cv2.waitKey(0)
cv2.destroyAllWindows()
cv2.waitKey(0)
for the eyes, which brings us to the reduction in computation as we are only going to detect eyes only in that area only.
Live Face and Eye detection
In this we will do the same detection of face and eyes but this time we will be doing it for the live stream form the webcam.
In most of the application you would find your face highlighted with a box around it, but here we have done something differently that you would find your face cropped out and eyes would identify in that only.
So in here we are importing both the face and eye classifier, and defined a function for doing all the processing for the face and eye detection.
And after that started the webcam stream and called the face detector function for getting the face and eyes detected.
The parameter we are defining inside the face detector function are the continuous images from live web cam stream
import cv2
import numpy as np
face_classifier = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
eye_classifier = cv2.CascadeClassifier('haarcascade_eye.xml')
def face_detector(img, size=0.5):
# Convert image to grayscale
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
faces = face_classifier.detectMultiScale(gray, 1.3, 5)
if faces is ():
return img
for (x,y,w,h) in faces:
x = x - 50
w = w + 50
y = y - 50
h = h + 50
cv2.rectangle(img,(x,y),(x+w,y+h),(255,0,0),2)
roi_gray = gray[y:y+h, x:x+w]
roi_color = img[y:y+h, x:x+w]
eyes = eye_classifier.detectMultiScale(roi_gray)
for (ex,ey,ew,eh) in eyes:
cv2.rectangle(roi_color,(ex,ey),(ex+ew,ey+eh),(0,0,255),2)
roi_color = cv2.flip(roi_color,1)
return roi_color
cap = cv2.VideoCapture(0)
while True:
ret, frame = cap.read()
cv2.imshow('Our Face Extractor', face_detector(frame))
if cv2.waitKey(1) == 13: #13 is the Enter Key
break
cap.release()
cv2.destroyAllWindows()
Tuning Cascade Classifiers
other than the input image have the following significance
ourClassifier.detectMultiScale(input image, Scale Factor , Min Neighbors)
Scale FactorSpecifies how much we reduce the image size each time we scale.
E.g.
in face detection we typically use 1.3.
This means we reduce the image by 30% each time it’s scaled.
Smaller values, like 1.05 will take longer to compute, but will increase the rate of detection.
Min NeighborsSpecifies the number of neighbors each potential window should have in order to consider it a positive detection.
Typically set between 3-6.
It acts as sensitivity setting, low values will sometimes detect multiples faces over a single face.
High values will ensure less false positives, but you may miss some faces.
Car and Pedestrian Detection in videos
Now we will detect pedestrian and cars in videos using the HAAR cascades, but in the case no video is loading and code compiles without an error you need to follow the following steps:
or opencv_ffmpeg310.dll (if you're using an X86 machine)
, just run these two lines of code, it would print the location where python is installed.
import sys
print(sys.executable)
import cv2
import numpy as np
# Create our body classifier
body_classifier = cv2.CascadeClassifier('haarcascade_fullbody.xml')
# Initiate video capture for video file, here we are using the video file in which pedestrians would be detected
cap = cv2.VideoCapture('walking.avi')
# Loop once video is successfully loaded
while cap.isOpened():
# Reading the each frame of the video
ret, frame = cap.read()
# here we are resizing the frame, to half of its size, we are doing to speed up the classification
# as larger images have lot more windows to slide over, so in overall we reducing the resolution
#of video by half that’s what 0.5 indicate, and we are also using quicker interpolation method that is #interlinear
frame = cv2.resize(frame, None,fx=0.5, fy=0.5, interpolation = cv2.INTER_LINEAR)
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
# Pass frame to our body classifier
bodies = body_classifier.detectMultiScale(gray, 1.2, 3)
# Extract bounding boxes for any bodies identified
for (x,y,w,h) in bodies:
cv2.rectangle(frame, (x, y), (x+w, y+h), (0, 255, 255), 2)
cv2.imshow('Pedestrians', frame)
if cv2.waitKey(1) == 13: #13 is the Enter Key
break
cap.release()
cv2.destroyAllWindows()
import cv2
import time
import numpy as np
# Create our body classifier
car_classifier = cv2.CascadeClassifier('haarcascade_car.xml')
# Initiate video capture for video file
cap = cv2.VideoCapture('cars.avi')
# Loop once video is successfully loaded
while cap.isOpened():
time.sleep(.05)
# Read first frame
ret, frame = cap.read()
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
# Pass frame to our car classifier
cars = car_classifier.detectMultiScale(gray, 1.4, 2)
# Extract bounding boxes for any bodies identified
for (x,y,w,h) in cars:
cv2.rectangle(frame, (x, y), (x+w, y+h), (0, 255, 255), 2)
cv2.imshow('Cars', frame)
if cv2.waitKey(1) == 13: #13 is the Enter Key
break
cap.release()
cv2.destroyAllWindows()
, it’s just a delay in frame rate so you can confirm that all the cars are correctly identified, or you can easily remove it just by adding a comment label to it.
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article/comparison-and-difference-between-pic-vs-avr-microcontroller-architecture
PIC vs AVR: Which Microcontroller to choose for your Application
Start with Project Requirement
Gather information of project such as Size of Project
Number of Peripherals and Sensors Used
Power Requirement
Budget of Project
Interfaces Requirement (like USB, SPI, I2C, UART etc),
Make a Basic Hardware Block Diagram,)
List down how many GPIO is needed
Analog to Digital Inputs (ADCs)
PWMs
Select the Right Architecture Needed i.e.
(8-bit, 16-bit, 32-bit)
Recognise Memory Requirement of project (RAM, Flash etc)
Look at the Featured Parameters
When all the information is gathered, then it is a right time to choose the microcontroller.
In this article the two competing microcontroller brand PIC and AVR will be compared on variety of parameters.
Depending upon the need of project to compare the two, look at the following parameters such as,
Frequency: Speed at which the microcontroller will operate
Number of I/O pins : Required ports and pins
RAM: All the variables and arrays declared(DATA) in most MCUs
Flash Memory: Whatever code you write goes here after compiling
Advanced Interfaces: Advanced interfaces such as USB, CAN and Ethernet.
Working Voltage: Working voltage of MCU such as 5V, 3.3V or Low voltage.
Target Connectors: The connectors for ease of circuit design and size.
The most of the parameters are similar in both PIC and AVR but there are some parameters that surely differ when compared.
Working Voltage
such as PIC16F and PIC18F because these PIC series used chip-erased method that need at least 4.5V to operate, and below 4.5V PIC programmers have to use row-erase algorithm which cannot erase locked device.
However this is not the case in AVR.
AVR has improved and launched the latest P (pico-power) variants such as ATmega328P which are extremely low-power.
Also the current ATtiny1634 has improved and comes with sleep modes to reduce power consumption when brownout is used which is very useful in battery powered devices.
and has launched some products based on picPower.
Target Connectors
Target connectors are very important when it comes to design and development.
AVR has defined 6 and 10-way ISP interfaces, which makes it easy to use whereas PIC doesn’t have it, so PIC programmers comes with flying leads or RJ11 sockets which are difficult to fit in the circuit.
with the target connectors whereas PIC still needs to rectify this.
Advanced Interfaces
In terms of advanced interfaces, then the PIC is surely the option as it has got their act with advanced features such as USB, CAN and Ethernet which is not the case in AVR.
However one can use external chips, such as FTDI USB to serial chips, Microchip Ethernet controllers or Philips CAN chips.
than AVR.
Development Environment
Other than this there are important features which makes both the microcontroller different from each other.
The ease of development environment is very important.
Below are some important parameters which will explain the ease of development environment:
Development IDE
C Compilers
Assemblers
which is of large 750MB size and is a bit clunky with more add-on features which makes it difficult and complicated for newbie electronic hobbyists.
However the users are switching to the older versions of AVR Studio such as 4.18 with service pack3 as it runs much faster and has basic features for development.
Both PIC and AVR comes with XC8 and WINAVR C Compilers respectively.
The PIC has bought out Hi-tech and have launched their own compiler XC8.
This is completely integrated into MPLAB X and functions well.
But WINAVR is ANSI C based on GCC compiler which makes it easy to port code and use standard libraries.
The free 4KB limited version of IAR C Compiler gives a flavour of professional compilers that costs much.
Since the AVR is designed for C in the beginning, the code output is small and fast.
The PIC has many features that make it well compared to AVR but it’s code becomes larger because of the structure of the PIC.
The paid version are available with more optimisation however the free version is not well optimised.
With three 16-bit pointer registers that simplify addressing and word operations, the AVR assembly language is very easy with lots of instructions and the ability to use all 32 registers as accumulator.
Whereas PIC assembler is not that well with everything forced to operate through the accumulator, forces to use bank switching all the time to access all the Special Function Registers.
Although MPLAB includes macros to simplify bank switching but it’s tedious and time consuming.
Also the lack of branch instructions, just skip and GOTO, which forces into convoluted structures and a bit confusing code.
The PIC series has some microcontroller series much faster but again limited to one accumulator.
Price and Availability
Other Features
Atmel Studio 7 has added Production ELF Files, which includes EEPROM, Flash and fuse data in one file.
Whereas AVR has integrated fuse data into their hex file format so fuse can be set in code.
This enables the transfer of project to production easier for PIC.
Conclusion
both are excellent low-cost devices which are not only be used in industries but also a popular choice among students and hobbyists.
Both are widely used and have good networks (forums, code examples) with active online presence.
Both have good community reach and support and both are available in wide sizes and form factor with core independent peripherals.
Microchip have taken over Atmel and now takes care both AVR and PIC.
At the end, it is well understood that learning microcontroller is like learning programming languages, as learning another will be much easier once you have learnt one.
It is regardless to say that whoever wins, but in almost all branch of engineering, there is no word such as “bestᾠwhereas the “Most Appropriate for Applicationᾠis well suited phrase.
It all depends on the requirements of a particular product, development method and manufacturing process.
So depending on project, one can choose well suited microcontroller out of PIC and AVR.
tutorial/nodal-voltage-analysis
Nodal Voltage Analysis
These two techniques follow the different rules and have different limitations.
Before going to analyze a circuit in a proper way, it is essential to identify which analysis technique is best suitable in terms of complexity and required time for analysis.
What to use ᾠMesh Analysis or Nodal Analysis?
The answer is hidden in the fact that how many numbers of voltage or current sources are available in the specific circuit or network.
If the targeted circuit network consists of current sources, then the nodal analysis will be less complicated and easier.
But, if a circuit has voltage sources then the mesh analysis technique is perfect and takes less calculation time.
In many circuits, both current and voltage sources are available.
In those situations, if the number of current sources is larger than the voltage sources, then the nodal analysis is still the best choice and one need to convert the voltage sources to an equivalent current sources.
Nodal Analysis
?
Nodal analysis is done on nodes.
, because each node can be assigned a voltage which is an essential parameter to analyze a node using the Node Analysis Method.
whether it is planer circuit or non-planer circuit.
Why? Because the voltage is a potential difference between two nodes.
Therefore, to differentiate, a reference is required.
This differentiation is done with a common or shared node which acts as a reference.
This reference node needs to be zero to get the perfect voltage level other than the ground reference of a circuit.
If these all are available, it is really easy to solve the circuit network.
Finding out nodes in the circuit
Finding out N-1 equations
Finding out N-1 voltage
Applying Kirchhoff's current law or KCL
Finding Voltage in Circuit using Nodal Analysis - Example
To understand the nodal analysis let's consider the below circuit network,
Let’s consider these five resistors as five resistive loads.
So, as discussed before, the numbers of nodes have been found.
Now, there is N-1 number of nodes that means 3-1 = 2 nodes are available in the circuit.
So, the remaining two nodes, Node-1 and Node-2 need to be assigned a voltage.
So the voltage level of Node-1 and Node-2 will be in reference to Node-3.
is applied.
The amount of current entering the nodes is equal to the current leaving from the nodes.
The arrows indicated the flow of currents Inodes in both Node-1 and Node-2.
The circuit’s current source is I1.
, the amount of current entering is I1, and the amount of current leaving is the sum of current across R1 and R2.
, the current of R1 is (V1 / R1) and the current of R2 is ((V1 ᾠV2) / R2).
So, applying Kirchoff's law, The Node-1 equation is
I1= V1/R1+ (V1 - V2)/R2 …‐quation:1]
and the resistor R4 and R5 can be combined to achieve a single resistance which is R4 + R5, the current through these two resistors will be V2/(R4 + R5).
Therefore, applying Kirchoff's current law, the equation of Node-2 can be formed as
(V2-V1 )/R2+ V2/R3+ V2/(R4 + R5)=0………………[Equation:2]
By solving these two equations, voltages at each node can be found without any further complexity.
Example of Nodal Voltage Analysis
Let's see a practical example-
which has a potential voltage of 0V.
There is one current source, I1, which is providing 10A of current and one voltage source which is providing 5V voltage.
,
I1= VR1+ (V1- V2)/R2
Therefore, by providing the exact value,
10 = V1 / 2 + (V1 - V2) / 1 or, 20 = 3V1 - 2V2…‐quation:1]
(V2 - V1) / R2 + V2/ R3 + V2 / (R4) = 0 or,
(V2 - V1) / 1+ V2 / 5+ (V2 - 5) / 3 = 0 or,
15V2 - 15V1 + 3V2 + 5V2 - 25=0
-15V1+ 23V2 = 25 ……………‐Equation: 2]
to verify the calculated results with simulated results.
And we got the same results as calculated above, check the simulated results in the picture below:
tutorial/object-detection-using-python-opencv
Object Detection using Python OpenCV
etc.
form the most important use case for computer vision, they are used to do powerful things such as
Labelling scenes
Robot Navigation
Self-driving cars
Body recognition (Microsoft Kinect)
Disease and cancer detection
Facial recognition
Handwriting recognition
Identifying objects in satellite images
Object recognition is the second level of object detection in which computer is able to recognize an object from multiple objects in an image and may be able to identify it.
Now, we will perform some image processing functions to find an object from an image.
Finding an Object from an Image
function for finding that object
import cv2
import numpy as np
image=cv2.imread('WaldoBeach.jpg')
cv2.imshow('people',image)
cv2.waitKey(0)
gray=cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)
template=cv2.imread('waldo.jpg',0)
#result of template matching of object over an image
result=cv2.matchTemplate(gray,template,cv2.TM_CCOEFF)
sin_val, max_val, min_loc, max_loc=cv2.minMaxLoc(result)
top_left=max_loc
#increasing the size of bounding rectangle by 50 pixels
bottom_right=(top_left[0]+50,top_left[1]+50)
cv2.rectangle(image, top_left, bottom_right, (0,255,0),5)
cv2.imshow('object found',image)
cv2.waitKey(0)
cv2.destroyAllWindows()
is used.
The whole function returns an array which is inputted in result, which is the result of the template matching procedure.
, which gives the coordinates or the bounding box where the object was found in an image, and when we get those coordinates draw a rectangle over it, and stretch a little dimensions of the box so the object can easily fit inside the rectangle.
which stands for correlation coefficient.
takes a “sliding windowᾠof the object and slides it over the image from left to right and top to bottom, one pixel at a time.
Then for each location, we compute the correlation coefficient to determine how “goodᾠor “badᾠthe match is.
to find where the good matches are in template matching.
Feature Description Theory
In template matching we slide a template image across a source image until a match is found.
But it is not the best method for object recognition, as it has severe limitations.
This method isn’t very resilient.
The following factors make template matching a bad choice for object detection.
Rotation renders this method ineffective.
Size (known as scaling) affects this as well.
Photometric changes (e.g.
brightness, contrast, hue etc.)
Distortion form view point changes (Affine).
The sky is an uninteresting feature, whereas as certain keypoints (marked in red circles) can be used for the detection of the above image (interesting Features).
The image shown above clearly shows the difference between the interesting feature and uninteresting feature.
Features are important as they can be used to analyze, describe and match images.
They have extensive use in:
Image alignment ᾠe.g panorma stiching (finding corresponding matches so we can stitch images together)
3D reconstruction
Robot navigation
Object recognition
Motion tracking
And more!
What defines the interest points?
Interesting areas carry a lot of distinct information and unique information of an area.
Typically, they are areas of high change of intensity, corners or edges and more.
But always be careful as noise can appear “informativeᾠwhen it is not! So try to blur so as to reduce noise.
ᾠThey can be found in multiple pictures of the same scene.
ᾠEach feature is somewhat unique and different to other features of the same scene.
ᾠSignificantly less features than pixels in the image.
ᾠFeature occupies a small area of the image and is robust to clutter and occlusion.
Corners are identified when shifting a window in any direction over that point gives a large change in intensity.
Corners are not the best cases for identifying the images, but yes they have certainly good use cases of them which make them handy to use.
So to identify corners in your image, imagine the green window we are looking at and the black one is the image we want to find corners in, and now when we move the window only inside the black box we see there is no change in intensity and hence the image is flat i.e.
no corners identified.
Now when we move the window in one direction we see that there is change of intensity in one direction only, hence it’s an edge not a corner.
When we move the window in the corner, and no matter in what direction we move the window now there is a change in intensity, and this is identified as a corner.
and works fairly well.
The following OpenCV function is used for the detection of the corners.
(input image, block size, ksize, k)
- Should be grayscale and float32 type.
- The size of neighborhood considered for corner detection
- Aperture parameter of Sobel derivative used.
- Harris detector free parameter in the equation
ᾠarray of corner locations (x,y)
, i.e.
image should be gray image of float 32 type.
import cv2
import numpy as np
image = cv2.imread('chess.jpg')
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
gray = np.float32(gray)
harris_corners = cv2.cornerHarris(gray, 3, 3, 0.05)
kernel = np.ones((7,7),np.uint8)
harris_corners = cv2.dilate(harris_corners, kernel, iterations = 2)
image[harris_corners > 0.025 * harris_corners.max() ] = [255, 127, 127]
cv2.imshow('Harris Corners', image)
cv2.waitKey(0)
cv2.destroyAllWindows()
returns the location of the corners, so as to visualize these tiny locations we use dilation so as to add pixels to the edges of the corners.
So to enlarge the corner we run the dilation twice.
And then we again do some thresholding to change the colors of the corners.
The following function is used for the same with the below mentioned parameters
cv2.goodFeaturesToTrack(input image, maxCorners, qualityLevel, minDistance)
Input Image - 8-bit or floating-point 32-bit, single-channel image.
maxCorners ᾠMaximum number of corners to return.
If there are more number of corners than the total numbers of corners which are actually found, then the strongest one of them is returned.
qualityLevel ᾠParameter characterizing the minimal accepted quality of image corners.
The parameter value is multiplied by the best corner quality measure (smallest eigenvalue).
The corners with the quality measure less than the product are rejected.
For example, if the best corner has the quality measure = 1500, and the qualityLevel=0.01 , then all the corners with the quality measured less than 15 are rejected.
minDistance ᾠMinimum possible Euclidean distance between the returned corners.
import cv2
import numpy as np
img = cv2.imread('chess.jpg')
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
corners = cv2.goodFeaturesToTrack(gray, 100, 0.01, 15)
for corner in corners:
x, y = corner[0]
x = int(x)
y = int(y)
cv2.rectangle(img,(x-10,y-10),(x+10,y+10),(0,255,0), 2)
cv2.imshow("Corners Found", img)
cv2.waitKey()
cv2.destroyAllWindows()
It also returns the array of location of the corners like previous method, so we iterate through each of the corner position and plot a rectangle over it.
Corner matching in images is tolerant of or corner detection don’t have any problem with image detection when the image is
Rotated
Translated (i.e.
shifts in image)
Slight photometric changes e.g.
brightness
or affine intensity
However, it is intolerant of:
Large changes in intensity or photometric
changes)
Scaling (i.e.
enlarging or shrinking)
SIFT, SURF, FAST, BRIEF & ORB Algorithms
Scale Invariant Feature Transform (SIFT)
are rotation invariant, which means even if the image is rotated we could still get the same corners.
It is also obvious as corners remain corners in rotated image also.
But when we scale the image, a corner may not be the corner as shown in the above image.
is used to detect interesting keypoints in an image using the difference of Gaussian method, these are the areas of the image where variation exceeds a certain threshold and are better than edge descriptor.
Then we create a vector descriptor for these interesting areas.
And the scale Invariance is achieved via the following process:
i.
Interesting points are scanned at several different scales.
ii.
The scale at which we meet a specific stability criteria, is then selected and encoded by the vector descriptor.
Therefore, regardless of the initial size, the more stable scale is found which allows us to be scale invariant.
of the key point using image gradient magnitudes.
Once we know the 2D direction, we can normalize this direction.
A full paper on SIFT can be read here:
.
Speeded Up Robust Features (SURF)
SURF is the speeded up version of SIFT, as the SIFT is quite computational expensive
SURF was developed to improve the speed of a scale invariant feature detector.
Instead of using the Difference of Gaussian approach, SURF uses Hessian matrix approximation to detect interesting points and uses the sum of Haar wavelet responses for orientation assignment.
As the SIFT and SURF are patented they are not freely available for commercial use however there are alternatives to these algorithms which are explained in brief here
Features from Accelerated Segment Test (FAST)
Key point detection only (no descriptor, we can use SIFT or SURF to compute that)
Used in real time applications
Here you can find the papers on FAST
Binary Robust Independent Elementary Features (BRIEF)
Computers descriptors quickly (instead of using SIFT or SURF)
it is quite fast.
Here you can find the paper on BRIEF
Oriented FAST and Rotated BRIEF (ORB)
Developed out of OpenCV Labs (not patented so free to use!)
Combines both Fast and Brief
Here you can find the paper on ORB
Using SIFT, SURF, FAST, BRIEF & ORB in OpenCV
The SIFT & SURF algorithms are patented by their respective creators, and while they are free to use in academic and research settings, you should technically be obtaining a license/permission from the creators if you are using them in a commercial (i.e.
for-profit) application.
SIFT
import cv2
import numpy as np
image = cv2.imread('paris.jpg')
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
Create SIFT Feature Detector object
sift = cv2.xfeatures2d.SIFT_create()
#Detect key points
keypoints = sift.detect(gray, None)
print("Number of keypoints Detected: ", len(keypoints))
image = cv2.drawKeypoints(image, keypoints, None, flags=cv2.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS)
cv2.imshow('Feature Method - SIFT', image)
cv2.waitKey(0)
cv2.destroyAllWindows()
Here the keypoints are (X,Y) coordinates extracted using sift detector and drawn over the image using cv2 draw keypoint function.
import cv2
import numpy as np
image = cv2.imread('paris.jpg')
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
orb = cv2.ORB_create()
# Determine key points
keypoints = orb.detect(gray, None)
keypoints, descriptors = orb.compute(gray, keypoints)
print("Number of keypoints Detected: ", len(keypoints))
image = cv2.drawKeypoints(image, keypoints, None, flags=cv2.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS)
cv2.imshow('Feature Method - ORB', image)
cv2.waitKey()
cv2.destroyAllWindows()
We can specify the number of keypoints which has maximum limit of 5000, however the default value is 500, i.e.
ORB automatically would detect best 500 keypoints if not specified for any value of keypoints.
and can be used as a portable device like Smartphones having Google Lens.
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article/smart-meter-monitor-your-electricity-though-wifi-link
IoT Smart Meter - Monitor your Electricity through the Wi-Fi Link
.
High-speed, robust wireless and wired communications.
Real-time or near-time registration of electricity use and possibly electricity generated locally e.g., in case of photovoltaic cells.
Accurate current and voltage measurement of current transformers, shunts or other sensors.
Security against magnetic and mechanical tampering
Description
; it is better if professionals who received appropriate technical training should operate the hardware if you want to implement.
This design uses the Texas Instruments CC3200MOD and MSP430i2040 as the development platform for communication and electrical metering, respectively.
Starting from the TI Design TIDM-3OUTSMTSTRP as the metering data source, a communication board designed using the CC3200MOD is added for Wi-Fi communication.
The metering data can then be read and the relay can be controlled by using a browser.
Circuit Diagram
(ADCs) allow accurate energy measurements, providing read of voltage, current, power (active, reactive, apparent), power factor, and frequency of three AC outlets.
The MSP430i2040 requires only a few passive external components to interface directly to the voltage divider and current shunt for voltage and current measurements.
The CC3200MOD is used in this design as the Wi-Fi controller that integrates an ARM Cortex-M4 MCU, allowing customers to develop an entire application with a single device.
With on-chip Wi-Fi, Internet, and robust security protocols, no prior Wi-Fi experience is required for faster development.
Constant-voltage (CV) and constant-current (CC) output regulation without optical coupler, has thermal shutdown, Low line and output overvoltage protection.
It has 7-channel high current sink drivers and supports up to 8-V output pullup voltage.
Design of Smart Meter
This design uses the MSP430i2040 as the metrology processor.
The TI Design TIDM-3OUTSMTSTRP is used as the platform of the metering part.
The hardware and firmware are slightly modified to add relay control alighted to zero crossing.
This design uses the HTTP Web Server on the CC3200 transfer data from the MSP430i2040 metering hardware.
This transfer allows metering data to be accessed using a web browser on any platform.
The HTTP server listens on the HTTP socket (default to 80) then handles the request (HTTP GET or HTTP POST) by retrieving the web page files from the serial flash.
The server then calls to an HTTP event handler to operate on the variable contents.
It then composes an HTTP response and sends back to the client over the Wi-Fi link.
To allow the metering data to be read with an HTML file with dynamic contents, the HTTP web server supports a set of predefined tokens, which will be replaced on-the-fly by the server, with dynamically generated content.
Some tokens are predefined in the HTTP server with additional tokens that can be defined in user application.
The HTTP server scans the HTML page for the "__SL_G_" prefix.
If the server finds a prefix, it checks the complete token.
Once it matches a known token, it replaces the token in the HTML with the appropriate data (string) that matches that token.
If the token is not in the predefined list, the server generates a get_token_value asynchronous event with the token name.
This request eventually calls to the HTTP event handler in the main.c code file.
The handler then interprets the token and responds to the token value with a send_token_value.
The HTTP web server uses this token value and returns it to the client.
To send data from client to the HTTP server, the server will check for the "__SL_P_" prefix.
Then the server goes over the parameters list and checks each variable name to see if it matches one of the known predefined tokens.
If the variable names match the predefined tokens, the server processes the values.
If the HTTP web server receives an HTTP POST request that contains tokens not in the predefined list, the server generates a post_token_value asynchronous event to the host, which contains the following information: form action name, token name, and token value.
The host can then process the required information.
To facilitate dynamic data, the user defined token is defined for the set of data to be retrieved:
for detailed explanation of event handling, hardware connection and to download the software files, see the link above with name TIDC-WIFIMETER-READING.
The software files are distributed using a self-extracting executable file, which default to install onto TIDCWIFI-METER-READING-SOFTWARE on the user’s desktop.
After the hardware is connected, download the firmware to its corresponding hardware.
Once the connection is done, you will reach programming part.
Set the Wi-Fi module to programming mode by switching the SOP2 DIP switch on the Wi-Fi module to the ON position.
After loading the firmware and setting it up as described in the link, you are ready to test.
Test Setup
To test the design, set up the hardware loaded with the firmware.
Then apply AC voltage to the AC input of the power strip.
The LEDs on the TIDM-3OUTSMTSTRP will light up; the LED on the Wi-Fi should flash as well.
To start testing, use a smartphone, tablet, or PC with Wi-Fi.
Look for the SSID "mysimplelink-XXXXXX" (where "XXXXXX" is a six-digit hexadecimal number) and connect to it.
Launch a browser and type in the URL "mysimplelink.net".The main page will be shown with the name of the meter in the upper left hand corner (which is "MSP430i2040 3 SOCKET POWER STRI").
Then click on "Reading"to see the details.
There is no doubt about the potential benefits of smart metering.
Smart meters are indispensable for all market parties:
for metering companies to decrease meter reading costs;
for grid operators who want to prepare their grid to the future;
for energy suppliers who want to introduce new, customer made services and reduce call centre cost;
for governments to reach energy saving & efficiency targets and to improve freemarket processes;
for end users to increase energy awareness and decrease energy use and energy cost.
Introduction of smart metering seems also a logical step in a world where all communication is digitalized and standardized (Internet, E-mail, SMS, chat boxes etc.) and where cost of 'digital intelligence' is still rapidly decreasing.
The effects of smart meters on health are not dangerous according to many officials.
Although the research is going on as all around the world people are reporting wireless is affecting their health.
Smart meters are found to be very accurate and getting more control over the electricity bills make us to have one.
About the Author
Priyanka Umraniworks asAnalog Layout Design Engineer with Texas Instruments, India
article/how-to-modify-clock-frequency-to-reduce-microcontroller-power-consumption
How to Modify the Clock Frequency to Reduce Microcontroller Power Consumption
Developers always have challenge delivering high levels of functionality and performance while simultaneously maximizing battery life.
Also when it comes to electronic products, the most important feature is the battery consumption.
It should be as less as possible to increase the device operation time.
The power management is very critical in portable and battery-powered applications.
Differences of microampere consumptions can lead to months or years of operating life which can increase or decrease the popularity and brand of the product in the market.
The increase in products demand more efficient optimization of battery use.
Nowadays, users demand longer battery backup with compact size of products so manufacturers are focusing on smaller battery size with super long battery life which is a questionable task.
But, the developers have come up with Power Saving Technologies after going through many factors and critical parameters affecting battery life.
which needs to be taken care when using MCU for low power applications.
Why to Modify Clock Frequency in Microcontrollers?
In order to avoid this loss, the developers need to take care of the appropriate frequency selection to run the microcontroller.
Now, it is not necessary that the frequency selection can be done initially, while setting up microcontroller, whereas it can be chosen in between the programming also.
There are many microcontroller which comes with bit selection to select desired operating frequency.
Also the microcontroller can run at multiple frequencies, so the developers have option to select appropriate frequency depending upon the application.
What is the effect of selecting multiple frequencies on the performance?
Low or High Frequency, which one to select?
It is not always the case when microcontroller has to deliver a high performance, there are several applications which need moderate performance of the microcontroller, in these type of applications the developers can decrease the operating frequency from GHz to MHz and even to minimum frequency required to run microcontroller.
Although, in some cases the optimum performance is required and also execution time is critical such as when driving external flash ADCs without FIFO buffer, or in video processing and many other applications, in these areas the developers can use the optimum frequency of microcontroller.
Even using in these kind of environment, the developers can code smartly to decrease the code length by choosing the right instruction.
loop.
So essentially choice of frequency is a trade-off between power consumption and required computation power.
Also the main advantage of working at low frequency is low supply current besides lower RFI (Radio Frequency Interference).
Supply Current (I) = Quiescent Current(Iq) + (K x Frequency)
The second term is predominant.
The RFI energy of a microcontroller is so small that it is very easy to filter.
Clock-Frequency Switching Technique
Also, the MCU that contains a PLL unit cannot exploit the benefits of frequency-switching technique that allows the MCU to operate at high frequency in the data-processing period and then return to low-frequency operation for the data transmission period.
Selecting Clock Management Modes of Operation
It is possible to switch between these modes allowing user to optimize the speed of the device while power consumption.
The crystal oscillator is a large consumer of power on any microcontroller, especially during low power operation.
The ring oscillator, used for quick starts from Stop mode, can also be used to provide an approximately 3 to 4MHz clock source during normal operation.
Although a crystal oscillator is still required at power-up, once the crystal has stabilized, device operation can be switched to the ring oscillator, realizing a power savings of as much as 25 mA.
The operating frequency of a microcontroller is the single biggest factor in determining power consumption.
The High-Speed Microcontroller family of microcontrollers supports different clock speed management modes that conserve power by slowing or stopping the internal clock.
These modes allow the system developer to maximize power savings with a minimum impact on performance.
Software execution from non-volatile memory or RAM
Developers must carefully consider whether software is executed from non-volatile memories or RAM in estimating the current consumption.
Executing from RAM can offer lower active current specifications; however, many applications are not small enough to execute from RAM alone and require programs be executed from non-volatile memory.
Most microcontroller applications require access to memories and peripherals during software execution.
This requires bus clocks to be enabled and needs to be considered in active current estimates.
Using the internal oscillator
Using internal oscillators and avoiding external oscillators can save significant energy.
As external oscillators draws more current resulting in more power usage.
Also it is not hard bound that one should use internal oscillator, as external oscillators are advisable to use when the applications require more clock frequency.
Conclusion
This technique can be used to improve the energy efficiency of a low-cost MCU.
Moreover, the amount of energy saving depends upon the difference between the operating frequencies, data-processing time and the architecture of the MCU.
The energy saving up to 66.9% can be achieved when using the frequency-switching technique compared with normal operation.
This article was created to help developers understand how the MCUs consume power in terms of frequency and can be optimized with modification of frequency.
interview/ashok-from-wisense-technology-on-how-they-build-low-power-wireless-sensor-networks-and-solutions
Ashok from Wisense Technology, on how they build low power wireless sensor networks and solutions
IoT solutions are everywhere today.
Be it Warehouse Management, Agriculture, Industrial Automation or Logistics everything is getting smart by communicating among the things and the Internet itself.
Any IoT Solution would include a sensor node, which measures a specific parameter using a dedicated sensor and then sends the information to could.
In a typical solution we will require more than one of these sensor nodes deployed at different locations to work collectively to provide useful data.
Most of the time these nodes need to be portable and will be powered by a battery hence they have to work with Low Power and still communicate with the could.
Wisense Technology offers easy to use wireless mesh network solutions for sensing and control applications.
With their expertise in wireless communication, sensors and electronics design they have implemented many IoT solutions using a wide range of sensor nodes.
Our Q&A Exchange is documented below
WiSense provides low power mesh network in sub1GHz frequency.
We have worked in the industrial and agricultural domain.
We develop both hardware and software which enables us to build products according to the use case.
As Senior Embedded engineer my job is to take care of product development from end to end, right from initial design to support the customer in the field.
Low Power, which increases battery life
We operate at Sub-GHz frequency band(865-867 MHz) which is free from data traffic
WiSense has provided solutions in all the verticals from Industrial to AgriTech.
The most challenging would be in the agriculture field, considering the harsh environment in which everything is put to test, right from Enclosure to power management of the device.
The major reason for operating in the 865-867MHz band would be
Less air traffic
Long Range
Low power for same range at 2.4GHz
Most of the time is spent on a messy table which is covered with PCBs and development boards.
We are incubated at NASSCOM CoE-IoT Bengaluru, where other IoT startups are incubated as well.
This would be the perfect place for the development of hardware product
The protocol for sensor node application should be lightweight as the sensor data is a very small packet of data.
This would be one of the important factors during the initial stages of development.
WiSense has worked on 50+ Sensors.
Temperature, Humidity, Soil Moisture, Soil Temperature, pH, Dissolved Oxygen in water, Rain, Proximity, Pressure are some of the sensors we have deployed till date.
There are many things which need to be considered while building firmware for the wireless devices.
Reliable software
Low power during non-operational mode
Information about all the components used in the product.
We use microcontrollers from MSP family.
The main reason for using MSP family is low cost and low power, which is critical for sensor network application.
Solar Cell and Super Capacitor is for the installations which need to be maintenance free.
Agriculture field is an example where the replacement of batteries for a large number of units is difficult.
We are currently team of 5 Members.
The team is led by Mr.Ramkrishnan who has 20+ years experience in Embedded system.
Work hard to improve Linkedin profile instead of Facebook profile.
Friends can wait but career will not.
tutorial/mesh-current-analysis
Mesh Current Analysis
Mesh and Nodal analysis
Mesh and nodal analysis have a specific set of rules and limited criteria to get the perfect result out of it.
For the working of a circuit, single or multiple voltage or current source or both is required.
Determination of Analysis technique is an important step in solving the circuit.
And it depends on the number of voltage or current source available in the specific circuit or networks.
So, for simpler calculation and to reduce complexity, it is a wiser choice to use mesh analysis where a large number of voltage sources are available.
At the same time if the circuit or networks deals with a large number of current sources, then Nodal analysis is the best choice.
But what if a circuit has both voltage and current sources? If a circuit has a larger number of voltage sources and few numbers of current sources, still Mesh analysis is the best choice, but the trick is to change the current sources into an equivalent voltage source.
Mesh Current Method or Analysis
To analyze a network with mesh analysis a certain condition needs to be fulfilled.
The mesh analysis is only applicable to planner circuits or networks.
Planner circuit is a simple circuit or network that can be drawn on a plane surface where no crossover is happening.
When the circuit needs a crossover then it is a nonplanar circuit.
It is simple and no crossover is present.
The circuit cannot be simplified asthere is crossover in the circuit.
Mesh analysis cannot be done in the nonplanar circuit and, it can only be done in the planar circuit.
To apply the Mesh Analysis, few simple steps are required to get the end result.
The first step is to identify whether it is a planar circuit or nonplanar circuit.
If it is a planar circuit then it needs to be simplified without any crossover.
Identifying the Meshes.
Identifying the voltage source.
Finding out the current circulating path
Applying Kirchoff's law in proper places.
Let's see how Mesh Analysis can be a helpful process for circuit level analysis.
Finding current in Circuit using Mesh Current Method
The above circuit contains two meshes.
It is a simple planner circuit where 4 resistors are present.
The first mesh is created using R1 and R3 resistors and the second mesh is created using R2, R4, and R3.
Two different value of current is flowing through each mesh.
The Voltage source is V1.
The circulating current in each mesh can be easily identified using the mesh equation.
.
, The Voltage of V1 is equal to the voltage difference of R1 and R3.
Therefore, as per the Kirchoff’s voltage law,
V1 = i1R1 + R3(i1 ᾠi2)……‐Equation: 1]
R3(i1 ᾠi2)) + i2R2 + i2R4 = 0)……‐Equation: 2]
Now we will see two practical examples to solve the circuit loops.
Solving Two Meshes using Mesh Current Analysis
There are two meshes in the circuitry.
By using the Ohms law, the voltage of each component is-
V1 = 5V
VR1 = i1 x 2 = 2i1
So, the voltage at
VR3 = (i1+i2) x 5 = 5(i1+i2)
As per the Kirchhoff's law,
V1 = 2i1 + 5(i1+i2)
5 = 7i1 + 5i2…‐Equation:1)
By using the Ohms law, the voltage of each component are-
V1 = 25V
VR2 = i2 x 10 = 10i2
VR3 = (i1 + i2) x 5 =5(i1 + i2)
As per the Kirchhoff's law,
V2 = 10i2 + 5(i1+i2)
25 = 5i1+15i2
5 = i1+ 3i2…..
(Equation: 2)
By solving this two equation we get,
i1 = .625A
i2 = 1.875A
The exact same circuit is replicated in Orcad Pspice and we get the same result
Solving Three Meshes using Mesh Current Analysis
Here is another classic Mesh analysis example
Let’s consider the below circuit network.
By using Mesh analysis, we will calculate the three currents in three meshes.
is also available.
, a ten Ampere current source is outside of the circuit network.
By using the Ohms law, the voltage of each component are-
V1 = 10V
Therefore, the voltage across the resistor R1
VR1 = (i2 ᾠi1) x 3 = 3 (i2 ᾠi1)
And for the resistor R2
VR2 = 2 x (i2 ᾠi3) = 2(i2 ᾠi3)
As per the Kirchhoff's law,
3(i2 ᾠi1) + 2(i2 ᾠi3) + 10 = 0 or -3i1 + 5i2 = -10‐Equation: 1)
is already known which is 10A.
value, Equation:2 can be formed.
-3i1 + 5i2 – 2i3 = -10
-30 + 5i2 – 2i3 = -10
5i2 ᾠ2i3 = 20‐Equation: 2)
V1, R3, and R2 are connected in series.
So, the same current is flowing through the three components which is i3.
By using the Ohms law, the voltage of each component is-
V1 = 10V
VR2 = 2 (i3 – i2)
VR3 = 1 x i3 = i3
As per the Kirchhoff's law,
i3 + 2 (i3 – i2) = 10
or, -2i2 + 3i3 = 10….[Equation:3]
= 8.18A.
the exact same result as calculated.
tutorial/image-segmentation-using-opencv
Image Segmentation using OpenCV - Extracting specific Areas of an image
In the previous tutorials, we have used OpenCV for basic image processing and done some advance image editing operations.
As we know, OpenCV is Open Source Commuter Vision Library which has C++, Python and Java interfaces and supports Windows, Linux, Mac OS, iOS and Android.
So it can be easily installed in Raspberry Pi with Python and Linux environment.
And Raspberry Pi with OpenCV and attached camera can be used to create many real-time image processing applications like Face detection, face lock, object tracking, car number plate detection, Home security system etc.
In this tutorial we will learn that how to do image segmentation using OpenCV.
The operations we are going to perform are listed below:
Segmentation and contours
Hierarchy and retrieval mode
Approximating contours and finding their convex hull
Conex Hull
Matching Contour
Identifying Shapes (circle, rectangle, triangle, square, star)
Line detection
Blob detection
Filtering the blobs ᾠcounting circles and ellipses
1. Segmentation and contours
to extract the parts of an image.
Also contours are very much important in
Object detection
Shape analysis
And they have very much broad field of application from the real world image analysis to medical image analysis such as in MRI’s
Let’s know how to implement contours in opencv, by extracting contours of squares.
import cv2
import numpy as np
image=cv2.imread('squares.jpg')
cv2.imshow('input image',image)
cv2.waitKey(0)
gray=cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)
edged=cv2.Canny(gray,30,200)
cv2.imshow('canny edges',edged)
cv2.waitKey(0)
#use a copy of your image, e.g.
- edged.copy(), since finding contours alter the image
#we have to add _, before the contours as an empty argument due to upgrade of the OpenCV version
_, contours, hierarchy=cv2.findContours(edged,cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_NONE)
cv2.imshow('canny edges after contouring', edged)
cv2.waitKey(0)
print(contours)
print('Numbers of contours found=' + str(len(contours)))
#use -1 as the 3rd parameter to draw all the contours
cv2.drawContours(image,contours,-1,(0,255,0),3)
cv2.imshow('contours',image)
cv2.waitKey(0)
cv2.destroyAllWindows()
- [array([[[368, 157]],
[[367, 158]],
[[366, 159]],
...,
[[371, 157]],
[[370, 157]],
[[369, 157]]],
dtype=int32),
array([[[520, 63]],
[[519, 64]],
[[518, 65]],
...,
[[523, 63]],
[[522, 63]],
[[521, 63]]], dtype=int32),array([[[16, 19]],
[[15, 20]],
[[15, 21]],
...,
[[19, 19]],
[[18, 19]],
[[17, 19]]], dtype=int32)]
So we have found a total of three contours.
this file tells how these contours looks like, as printed in above console output.
In the above console output we have a matrix which looks like coordinates of x, y points.
OpenCV stores contours in a lists of lists.
We can simply show the above console output as follows:
[array([[[368, 157]], array([[[520, 63]], array([[[16, 19]],
[[367, 158]], [[519, 64]], [[15, 20]],
[[366, 159]], [[518, 65]], [[15, 21]],
..., ..., ...,
[[371, 157]], [[523, 63]], [[19, 19]],
[[370, 157]], [[522, 63]], [[18, 19]],
[[369, 157]]], dtype=int32), [[521, 63]]], dtype=int32), [[17, 19]]], dtype=int32)]
Now, as we use the length function on contour file, we get the length equal to 3, it means there were three lists of lists in that file, i.e.
three contours.
is the first element in that array and that list contains list of all the coordinates and these coordinates are the points along the contours that we just saw, as the green rectangular boxes.
cv2.CHAIN_APPROX_NONE
cv2.CHAIN_APPROX_SIMPLE
stores all the boundary point, but we don’t necessarily need all the boundary points, if the point forms a straight line, we only need the start point and ending point on that line.
instead only provides the start and end points of the bounding contours, the result is much more efficient storage of contour information.
_, contours,hierarchy=cv2.findContours(edged,cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_NONE)
So we have learned about contours and approximation method, now let’s explore hierarchy and retrieval mode.
2. Hierarchy and Retrieval Mode
Retrieval mode defines the hierarchy in contours like sub contours, or external contour or all the contours.
Now there are four retrieval modes sorted on the hierarchy types.
ᾠretrieves all the contours.
retrieves external or outer contours only.
retrieves all in a 2-level hierarchy.
retrieves all in a full hierarchy.
Now let’s illustrate the difference between the first two retrieval modes, cv2.RETR_LIST and cv2.RETR_EXTERNAL.
import cv2
import numpy as np
image=cv2.imread('square donut.jpg')
cv2.imshow('input image',image)
cv2.waitKey(0)
gray=cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)
edged=cv2.Canny(gray,30,200)
cv2.imshow('canny edges',edged)
cv2.waitKey(0)
#use a copy of your image, e.g.
- edged.copy(), since finding contours alter the image
#we have to add _, before the contours as an empty argument due to upgrade of the open cv version
_, contours,hierarchy=cv2.findContours(edged,cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_NONE)
cv2.imshow('canny edges after contouring', edged)
cv2.waitKey(0)
print(contours)
print('Numbers of contours found=' + str(len(contours)))
#use -1 as the 3rd parameter to draw all the contours
cv2.drawContours(image,contours,-1,(0,255,0),3)
cv2.imshow('contours',image)
cv2.waitKey(0)
cv2.destroyAllWindows
import cv2
import numpy as np
image=cv2.imread('square donut.jpg')
cv2.imshow('input image',image)
cv2.waitKey(0)
gray=cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)
edged=cv2.Canny(gray,30,200)
cv2.imshow('canny edges',edged)
cv2.waitKey(0)
#use a copy of your image, e.g.
- edged.copy(), since finding contours alter the image
#we have to add _, before the contours as an empty argument due to upgrade of the open cv version
_, contours,hierarchy=cv2.findContours(edged,cv2.RETR_LIST,cv2.CHAIN_APPROX_NONE)
cv2.imshow('canny edges after contouring', edged)
cv2.waitKey(0)
print(contours)
print('Numbers of contours found=' + str(len(contours)))
#use -1 as the 3rd parameter to draw all the contours
cv2.drawContours(image,contours,-1,(0,255,0),3)
cv2.imshow('contours',image)
cv2.waitKey(0)
cv2.destroyAllWindows()
, in cv2.RETR_EXTERNNAL only the outer contours are being taken into account while the inner contours are being ignored.
inner contours are also being taken into account.
3. Approximating Contours and Finding their Convex hull
In approximating contours, a contour shape is approximated over another contour shape, which may be not that much similar to the first contour shape.
function of openCV which is explained below
cv2.approxPolyDP(contour, approximation accuracy, closed)
Contour ᾠis the individual contour we wish to approximate.
Approximation Accuracy- important parameter in determining the accuracy of approximation, small value give precise approximation, large values gives more generic information.
A good thumb rule is less than 5% of contour perimeter.
Closed ᾠa Boolean value that states whether the approximate contour could be open or closed.
import numpy as np
import cv2
image=cv2.imread('house.jpg')
orig_image=image.copy()
cv2.imshow('original image',orig_image)
cv2.waitKey(0)
gray=cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)
ret, thresh=cv2.threshold(gray,127,255,cv2.THRESH_BINARY_INV)
_, contours, hierarchy=cv2.findContours(thresh.copy(),cv2.RETR_LIST,cv2.CHAIN_APPROX_NONE)
for c in contours:
x,y,w,h=cv2.boundingRect(c)
cv2.rectangle(orig_image,(x,y),(x+w,y+h),(0,0,255),2)
cv2.imshow('Bounding rect',orig_image)
cv2.waitKey(0)
for c in contours:
#calculate accuracy as a percent of contour perimeter
accuracy=0.03*cv2.arcLength(c,True)
approx=cv2.approxPolyDP(c,accuracy,True)
cv2.drawContours(image,[approx],0,(0,255,0),2)
cv2.imshow('Approx polyDP', image)
cv2.waitKey(0)
cv2.destroyAllWindows()
4. Convex Hull
Convex hull is basically the outer edges, represented by drawing lines over a given figure.
import cv2
import numpy as np
image=cv2.imread('star.jpg')
gray=cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)
cv2.imshow('original image',image)
cv2.waitKey(0)
ret, thresh=cv2.threshold(gray,176,255,0)
_, contours, hierarchy=cv2.findContours(thresh.copy(),cv2.RETR_LIST,cv2.CHAIN_APPROX_NONE)
n=len(contours)-1
contours=sorted(contours,key=cv2.contourArea,reverse=False)[:n]
for c in contours:
hull=cv2.convexHull(c)
cv2.drawContours(image,[hull],0,(0,255,0),2)
cv2.imshow('convex hull',image)
cv2.waitKey(0)
cv2.destroyAllWindows()
5. Matching Contour by shapes
cv2.matchShapes(contour template, contour method, method parameter)
Output ᾠmatch value(lower value means a closer match)
ᾠThis is our reference contour that we are trying to find in a new image.
ᾠThe individual contour we are checking against.
ᾠType of contour matching (1,2,3).
ᾠleave alone as 0.0 (not utilized in python opencv)
import cv2
import numpy as np
template= cv2.imread('star.jpg',0)
cv2.imshow('template',template)
cv2.waitKey(0)
target=cv2.imread('shapestomatch.jpg')
gray=cv2.cvtColor(target,cv2.COLOR_BGR2GRAY)
ret,thresh1=cv2.threshold(template,127,255,0)
ret,thresh2=cv2.threshold(gray,127,255,0)
_,contours,hierarhy=cv2.findContours(thresh1,cv2.RETR_CCOMP,cv2.CHAIN_APPROX_SIMPLE)
#we need to sort the contours by area so we can remove the largest contour which is
sorted_contours=sorted(contours, key=cv2.contourArea, reverse=True)
#we extract the second largest contour which will be our template contour
tempelate_contour=contours[1]
#extract the contours from the second target image
_,contours,hierarchy=cv2.findContours(thresh2,cv2.RETR_CCOMP,cv2.CHAIN_APPROX_SIMPLE)
for c in contours:
#iterate through each contour in the target image and use cv2.matchShape to compare the contour shape
match=cv2.matchShapes(tempelate_contour,c,1,0.0)
print("match")
#if match value is less than 0.15
if match<0.16:
closest_contour=c
else:
closest_contour=[]
cv2.drawContours(target,[closest_contour],-1,(0,255,0),3)
cv2.imshow('output',target)
cv2.waitKey(0)
cv2.destroyAllWindows()
0.16818605122199104
0.19946910256158912
0.18949760627309664
0.11101058276281539
,0.0) method values which varies from 1,2 and 3, for each value you will get different match values in console output.
OpenCV can also be used for detecting different types of shapes automatically from the image.
By using below code we will be able to detect circle, rectangle, triangle, square and stars from the image.
import cv2
import numpy as np
image=cv2.imread('shapes.jpg')
gray=cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)
cv2.imshow('identifying shapes',image)
cv2.waitKey(0)
ret, thresh=cv2.threshold(gray,127,255,1)
_,contours,hierarchy=cv2.findContours(thresh.copy(),cv2.RETR_LIST,cv2.CHAIN_APPROX_NONE)
Get approximate polygons
approx = cv2.approxPolyDP(cnt,0.01*cv2.arcLength(cnt,True),True)
if len(approx)==3:
shape_name="Triangle"
cv2.drawContours(image,[cnt],0,(0,255,0),-1)
M=cv2.moments(cnt)
cx=int(M['m10']/M['m00'])
cy=int(M['m01']/M['m00'])
cv2.putText(image,shape_name,(cx-50,cy),cv2.FONT_HERSHEY_SIMPLEX,1,(0,0,0),1)
elif len(approx)==4:
x,y,w,h=cv2.boundingRect(cnt)
M=cv2.moments(cnt)
cx=int(M['m10']/M['m00'])
cy=int(M['m01']/M['m00'])
#cv2.boundingRect return the left width and height in pixels, starting from the top
#left corner, for square it would be roughly same
if abs(w-h) <= 3:
shape_name="square"
#find contour center to place text at center
cv2.drawContours(image,[cnt],0,(0,125,255),-1)
cv2.putText(image,shape_name,(cx-50,cy),cv2.FONT_HERSHEY_SIMPLEX,1,(0,0,0),1)
else:
shape_name="Reactangle"
#find contour center to place text at center
cv2.drawContours(image,[cnt],0,(0,0,255),-1)
M=cv2.moments(cnt)
cx=int(M['m10']/M['m00'])
cy=int(M['m01']/M['m00'])
cv2.putText(image,shape_name,(cx-50,cy),cv2.FONT_HERSHEY_SIMPLEX,1,(0,0,0),1)
elif len(approx)==10:
shape_name='star'
cv2.drawContours(image,[cnt],0,(255,255,0),-1)
M=cv2.moments(cnt)
cx=int(M['m10']/M['m00'])
cy=int(M['m01']/M['m00'])
cv2.putText(image,shape_name,(cx-50,cy),cv2.FONT_HERSHEY_SIMPLEX,1,(0,0,0),1)
elif len(approx)>=15:
shape_name='circle'
cv2.drawContours(image,[cnt],0,(0,255,255),-1)
M=cv2.moments(cnt)
cx=int(M['m10']/M['m00'])
cy=int(M['m01']/M['m00'])
cv2.putText(image,shape_name,(cx-50,cy),cv2.FONT_HERSHEY_SIMPLEX,1,(0,0,0),1)
cv2.imshow('identifying shapes', image)
cv2.waitKey(0)
cv2.destroyAllWindows()
7. Line Detection
, and has a promising use in the real world.
Autonomous cars use line detection algorithms for the detection of lanes and roads.
In line detection we will deal with two algorithms,
Hough Line Algorithm
Probalistic Hough Line Algorithm.
However, in OpenCV line is represented by another way
The equation above ρ=xcos +ysincos is the OpenCV representation of the line, wherein ρ is the perpendicular distance of line from origin and is the angle formed by the normal of this line to the origin (measured in radians, wherein 1pi radians/180 = 1 degree).
wherein threshold is minimum vote for it to be considered a line.
Now let’s detect lines for a box image with the help of Hough line function of opencv.
import cv2
import numpy as np
image=cv2.imread('box.jpg')
gray=cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)
edges=cv2.Canny(gray,100,170,apertureSize=3)
#theta accuracy of (np.pi / 180) which is 1 degree
#line threshold is set to 240(number of points on line)
lines=cv2.HoughLines(edges, 1, np.pi/180, 240)
#we iterate through each line and convert into the format
#required by cv2.lines(i.e.
requiring end points)
for i in range(0,len(lines)):
for rho, theta in lines[i]:
a=np.cos(theta)
b=np.sin(theta)
x0=a*rho
y0=b*rho
x1=int(x0+1000*(-b))
y1=int(y0+1000*(a))
x2=int(x0-1000*(-b))
y2=int(y0-1000*(a))
cv2.line(image,(x1,y1),(x2,y2),(0,255,0),2)
cv2.imshow('hough lines',image)
cv2.waitKey(0)
cv2.destroyAllWindows()
Now let’s repeat above line detection with other algorithm of probabilistic Hough line.
The idea behind probabilistic Hough line is to take a random subset of points sufficient enough for line detection.
Now let’s detect box lines with the help of probabilistic Hough lines.
import cv2
import numpy as np
image=cv2.imread('box.jpg')
gray=cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)
edges=cv2.Canny(gray,50,150,apertureSize=3)
#again we use the same rho and theta accuracies
#however, we specify a minimum vote(pts along line) of 100
#and min line length of 5 pixels and max gap between the lines of 10 pixels
lines=cv2.HoughLinesP(edges,1,np.pi/180,100,100,10)
for i in range(0,len(lines)):
for x1,y1,x2,y2 in lines[i]:
cv2.line(image,(x1,y1),(x2,y2),(0,255,0),3)
cv2.imshow('probalistic hough lines',image)
cv2.waitKey(0)
cv2.destroyAllWindows
8. Blob detection
Blobs can be described as a group of connected pixels that all share a common property.
The method to use OpenCV blob detector is described through this flow chart.
which takes the following arguments.
cv2.drawKeypoints(input image,keypoints,blank_output_array,color,flags)
where in the flags could be
here is pretty much nothing but one by one matrix of zeros
Now let’s perform the blob detection on an image of sunflowers, where the blobs would be the central parts of the flower as they are common among all the flowers.
import cv2
import numpy as np
image=cv2.imread('Sunflowers.jpg',cv2.IMREAD_GRAYSCALE)
detector=cv2.SimpleBlobDetector_create()
keypoints= detector.detect(image)
#cv2.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS ensure the
#size of circle corresponds to the size of blob
blank=np.zeros((1,1))
blobs=cv2.drawKeypoints(image,keypoints,blank,(0,255,255),cv2.DRAW_MATCHES_FLAGS_DEFAULT)
cv2.imshow('blobs',blobs)
cv2.waitKey(0)
cv2.destroyAllWindows()
Even though the code works fine but some of the blobs are missed due to uneven sizes of the flowers as the flowers in the front are big as compared to the flowers at the end.
9. Filtering the Blobs ᾠCounting Circles and Ellipses
We can use parameters for filtering the blobs according to their shape, size and color.
For using parameters with blob detector we use the OpenCV’s function
cv2.SimpleBlobDetector_Params()
We will see filtering the blobs by mainly these four parameters listed below:
params.filterByArea=True/False
params.minArea=pixels
params.maxArea=pixels
params.filterByCircularity=True/False
params.minCircularity= 1 being perfect, 0 being opposite
params.filterByConvexity= True/False
params.minConvexity=Area
params.filterByInertia=True/False
params.minInertiaRatio=0.01
Now let’s try to filter blobs by above mentioned parameters
import cv2
import numpy as np
image=cv2.imread('blobs.jpg')
cv2.imshow('original image', image)
cv2.waitKey(0)
detector=cv2.SimpleBlobDetector_create()
keypoints=detector.detect(image)
blank=np.zeros((1,1))
blobs=cv2.drawKeypoints(image,keypoints,blank,(0,0,255),cv2.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS)
number_of_blobs=len(keypoints)
text="total no of blobs"+str(len(keypoints))
cv2.putText(blobs,text,(20,550),cv2.FONT_HERSHEY_SIMPLEX,1,(100,0,255),2)
cv2.imshow('blob using default parameters',blobs)
cv2.waitKey(0)
#initialize parameter setting using cv2.SimpleBlobDetector
params=cv2.SimpleBlobDetector_Params()
params.filterByArea=True
params.minArea=100
params.filterByCircularity=True
params.minCircularity=0.9
params.filterByConvexity=False
params.minConvexity=0.2
params.filterByInertia=True
params.minInertiaRatio=0.01
detector=cv2.SimpleBlobDetector_create(params)
keypoints=detector.detect(image)
blank=np.zeros((1,1))
blobs=cv2.drawKeypoints(image,keypoints,blank,(0,255,0),cv2.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS)
number_of_blobs=len(keypoints)
text="total no of circular blobs"+str(len(keypoints))
cv2.putText(blobs,text,(20,550),cv2.FONT_HERSHEY_SIMPLEX,1,(0,100,255),2)
cv2.imshow('filtering circular blobs',blobs)
cv2.waitKey(0)
cv2.destroyAllWindows()
and you will be able to make something cool with Computer Vision.
interview/yuvraj-tomar-founder-of-thinqbot-technologies-tells-about-his-smart-home-solutions-hardware-startup
Yuvraj Tomar, Founder of Thinqbot tells us how his smart home solutions could convert any home into a smart one
With the advent of wireless technology and IoT Solutions, Smart Home concepts are quickly getting popular.
The Internet is already filled with a plethora of Home Automation Solutions that could make our life easier and secure.
Moreover, who would say no to a home that could automatically turn on the AC, set the lights and tune in to your favourite Playlist just when you step in from a hard day at work.
For me, this would surely be like getting one step closer to my Iron Man dreams.
But, are we ready for such things yet? What would it actually take to automate my home and how will that solution work? Most importantly would I have to re-wire my house all again?
, a company that provides home automation solutions.
At Thinqbot, Yuvraj oversees the full-stack technology design while developing viable business strategies and strengthening partner network.
Before starting Thinqbot, Yuvraj had software development stints at KDE, Google, and Cisco.
In 2013, I was looking for a solution to automate my apartment.
My landlord wouldn't allow rewiring and changing the electrical layout of the home, and the available solutions didn’t cater to my needs.
I researched a lot but couldn't find the ideal retrofit solution.
The products that I bought didn't give a satisfactory user experience and I felt that smart homes in general, are "broken".
I took it up as a personal challenge to fix it by creating a solution that can be installed in any home (whether old or new), without changing the wiring layout of the house, packed with all the features and integrations in an intuitive 3D UI.
That was the start of Thinqbot.
We talk about smart lights, and smart appliances when talking about the smart home, but we often forget the basic entity which should be automated for a proper experience - the switchboard.
There is no solution that can retrofit inside your switchboard and cater to a dimmable load plus a heavy load, on one board, unless they have to rewire the switch panel or change the electrical layout.
To battle this age-old proposition, we have created a modular hardware design that can retrofit inside any switchboard, old or new, big or small.
The user can even mix and match a combination of heavy, regular or dimmable loads on one board till 8 appliances on one board.
One of our biggest advantages is that we don't require any change in the existing electrical wiring of the house.
Our solution works on 6LoWPAN, which sets up a wireless mesh covering the whole home or even a mansion.
On the software side, we have created a new UI for interacting with the physical devices, in 3D.
It feels intuitive, and can even be used by kids and elderly alike..
Due to the limitations of existing wireless retrofit solutions, the only way to fully and reliably automate your home is to install Crestron or Control4 solutions; which are mostly wired solutions (Cat6).
So the customer ends up paying a premium for installation and wiring just for a basic experience.
This is also the biggest reason why the retrofit smart home market hasn't taken off.
Even after all the hassle, the customer gets a UI that looks straight out from the 90s.
Thus people who are looking to renovate their home or buying a new home are the ones opting for these solutions as the inertia and complexity of installation isn’t an inhibiting factor in these scenarios.
Because of the high price tag, home automation has always had the perception of luxury and not a necessity.
The market is slowly making a shift towards retrofit and affordable solutions, and more people have begun experimenting with DIY solutions as well.
A lot of promising startups are there in this space but none of them cater to the whole-home market like the breadth and features of the incumbents.
It is just waiting for disruption where, if a solution that can offer Crestron like features and reliability at affordable prices, a monumental shift in consumer adoption will happen.
It wasn’t a single product as such, our first rollout included a hub and a unified switchboard module which could control up to 4 devices per board.
From then on we had a lot of iterations with the hardware design and expanded our portfolio to accommodate security and entertainment offerings.
It’s an adage in the tech world that "Hardware is hard".
After all, a programmer can ship an app; armed with just a whiteboard, a marker, some carbonated drinks and noodles, and a montage of "wired-in" coding sprees on a computer.
But a new piece of hardware has an entirely different story.
It has to go through design revisions, materials tests, and manufacturing regulations before it sees the light of day.
In hindsight, building a hardware company in India has been difficult and it would have been a lot easier in Shenzhen, or Hong Kong.
But the return of investment on talent across the entire stack is unbeatable in India, and that plays a significant advantage to start any business here.
Our solution is comprised of 5 layers:
- sensors sending data and actuators performing control actions.
- wireless network layer for transmitting data across sensors
- local intelligence for automation, voice, image, and media
- servers hosted on AWS for supporting features and requirements
- 3D UI developed in a game-engine for controlling and viewing the home
Then we expose our APIs locally and over the cloud for 3rd Party Integrations and services.
6LoWPAN is an acronym for IPv6 over Low-powered Wireless Personal Area Networks.
It is a mesh networking technology (similar to Zigbee and Z-Wave), however it is IPv6 based and has a lot of functionalities making it suitable for managing IoT devices.
In fact, 6LoWPAN practically has little adoption in the consumer space; LIFX Smart Bulbs, Tado Thermostats, Sensibo IR Blasters being some of them.
The obvious answer is that because the protocol is much ‘youngerᾠthan its competitors and the pieces needed to make it useful (like the border router), haven’t existed for long.
Having said that, 6LoWPAN is proving to be a strong contender to replace wired solutions for large installations, and prove the reliability of wireless sensor networks.
There are companies in Europe (Sensinode and Cetic) that are using 6LoWPAN for entire buildings, let alone homes.
Qube exposes a bundle of wireless protocols for connectivity, namely: WiFi, BLE, 6LoWPAN and IR.
All our products use 6LoWPAN and WiFi to connect to Qube and thereby establish the link to talk to user app or the cloud.
The platinum version of Qube is geared towards security and entertainment features compared to the basic version which is targeted towards automation.
In Qube (Platinum) we have the following bundle of features available:
Make any dumb TV smart by connecting it to Qube and access everything including your TV Guide, social media accounts (such as Netflix), and even your stored media content on an external hard-drive connected to Qube.
No need for Dropbox or Google Drive, connect a hard-disk to Qube and make it your personal cloud.
We encrypt all user data and bundle it with a VPN service to provide complete anonymity.
You can now watch shows on Netflix US, or stream from Spotify UK, at your home in India.
Even better, think torrents.
Universal Streaming incorporates AirPlay, GoogleCast and Miracast in one, allowing you to transform your TV or projector into a universal screen mirroring receiver, instantly turning the room into a collaborative space.
Atom is the starting point for experiencing automation.
It connects via WiFi and has a relay module inside for controlling appliances.
As it can directly connect to the cloud, the hub is not required to control Atom products and is thus affordable for users who want to automate a few appliances to begin with.
We’ve designed Spark in a modular fashion and that is the sole reason why we are able to retrofit inside switchboards.
Typical in-switch control modules have a power supply, a networking module, a control module and actuator units; assembled in one board.
We’ve designed all those parts as stand-alone units which snap-fit behind the switches.
That way we make use of the available real-estate between the switch terminals, thereby occupying only 12-14mm behind the switchboards.
Such a configuration makes it easier for any household electrician to install the Spark modules.
Beam is an Infrared and RF emitter.
It can control any device that works with an IR/RF remote, such as TVs, ACs, Set-Top- Boxes, Home-Theatre Systems, Curtains, Color LED Strips, etc; making it the perfect device for your Living room and Bedroom.
There is a learning component also built in Beam, in which it can learn all the remote commands and subsequently replicate them for usage.
We store raw IR and RF data for replication, that makes our firmware protocol independent to control IR and RF signals.
Beam has 7 IR emitter diodes which can project upto 10m in line of sight with an angular spread of 120 degrees.
The diodes are placed in a manner that it can cover the available hemisphere in its range.
Neon Strips consume 72W and the Neon Panels consume 0.5W to 2W per panel.
Neon Strips are priced competitive to Syska LED Strips, Neon Panels start at INR 3k per panel (minimum order of 9 panels).
There are various tenets to making your home smart ᾠautomation, security, and entertainment.
The best value comes when all these facets are integrated together.
In case you want to focus on a particular category, then the best place to start would be to choose products in that category and customize it later as your needs grow.
The language of home automation is such that the consumer lacks clarity of what he’s getting into before making the purchase.
To avoid this, we schedule a feasibility call and visit to the customer’s premises to understand their automation needs properly and then guide them to prepare the best solution in an A-la-Carte manner.
I use a MacBook Pro which runs all the utilities for my firmware programming, middleware programming, app development and cloud computing.
Most of my development tools are also divided across these 4 domains:
Firmware: ST
PCB: KiCAD
Middleware: Bash, Vim, Cscope (Not a fan of IDE for middleware programming)
App: 3DS Max, Unity3D, XCode, Microsoft Visual Develop
Cloud: PyCharm, GoLand, Bash
Other: SnapMaker
The supply chain is scattered across Shenzhen, Taiwan, Hong Kong, Ahmedabad, NCR, Chennai and Bangalore.
Sometimes we source components through AliExpress and AliBaba for prototyping, especially when the volumes are small.
Establishing and managing the supply chain has been an intensive task.
Ideally, all these processes should be streamlined under a few Contract Manufacturers but we’ll tackle that at a later stage when we move the entire SCM to Shenzhen.
Leaving a legacy is a fool's errand.
Play by the rules and win.
Seek no destination or no glory.
Think of it like an orchestra.
Compose, structure, arrange.
And gather the people
Who all share the common vision
To wander and create a beautiful symphony.
article/temperature-monitoring-system-in-electric-vehicles
Temperature Monitoring System in Electric Vehicles
Automotive manufacturers all over the world are focused on vehicle electrification.
There is a need for cars to charge more quickly and have a more extended range on a single charge.
This implies, electrical and electronics circuit within the vehicle should be able to handle extremely high power and manage losses effectively.
There is a need for robust thermal-management solutions to ensure that safety-critical applications remain operational.
In addition to heat produced by vehicle by itself, just think of all the thermal tolerance that your car and its electronics must have in order to handle wide ambient temperature ranges.
For example, in India coldest regions face temperature much below 0°C during winter and it could be exceeding 45°C during summer for some other regions.
(BMS) also require fine resolution of temperature measurement on cell level.
The one component that must be accurate at extreme temperatures in order to protect the system is no doubt thetemperature sensor.
Accurate temperature information allows the processor to temperature-compensate the system so that the electronic modules can optimize their performance and maximize their reliability no matter the driving conditions.
This includes temperature sensing of power switches, power magnetic components, heat sinks, PCB, etc.
Temperature data also helps to run cooling system in a controlled manner.
(ADC) channel of a microcontroller (MCU).
However, there are a few NTC characteristics that can make it difficult to use in an automotive environment.
As previously mentioned, the resistance of an NTC varies inversely with temperature, but the relationship is nonlinear.
Figure below shows an example of a typical NTC-based voltage divider.
When you consider the heat generated from various subsystems within EV and climates that exist in different regions of the world, it becomes clear that a vehicle’s semiconductor components will be exposed to a wide range of temperatures (-40°C to 150°C).
Over a wide temperature range, the nonlinear behavior of the NTC will make it difficult to reduce errors as you translate a voltage reading to an actual temperature measurement.
The error introduced from an NTC’s nonlinear curve lowers the accuracy of any NTC-based temperature reading.
An analog output IC temperature sensor will have a more linear response when compared to NTCs as shown in the figure above.
And MCU can easily translate the voltage into temperature data with more accuracy and speed.
Finally, analog temperature sensor ICs often have superior temperature sensitivity at high temperatures compared to NTCs.
ICtemperature sensorsshare a market category with other sensing technologies like thermistors, resistance temperature detectors (RTD) and thermocouples, but ICs have some important benefits when good accuracy is required over wide temperatures like the AEC-Q100 Grade 0 range (-40°C to 150°C).
First, the accuracy limits of an IC temperature sensor are given in degrees Celsius in the data sheet across the full operating range; conversely, a typical negative temperature coefficient (NTC) thermistor may only specify the resistance accuracy in percent at a single temperature point.
You would then need to carefully calculate the total system accuracy for the full temperature range when using a thermistor.
In fact, be careful to check the operating conditions specifying any sensor’s accuracy.
When selecting an IC, keep in mind that there are several types ᾠwith various merits for different automotive applications.
Analog output: Devices like theLMT87-Q1(available in AEC-Q100 Grade 0) are simple, three-pin solutions that offer multiple gain options to match best with your selected analog-to-digital converter (ADC), which lets you determine the overall resolution.
You also get the benefit of low operating power consumption that is comparatively consistent over the temperature range vs.
a thermistor.
This means you don’t have to trade off power for noise performance.
Digital output: To further simplify your thermal management implementation, TI offers digital temperature sensors that will directly communicate temperature over interfaces like I2C or Serial Peripheral Interface (SPI).
For example, TMP102-Q1will monitor temperature with an accuracy of ±3.0°C from -40°C to +125°C and directly communicate the temperature over I2C to the MCU.
This completely removes the need for any sort of look up table or calculation based on a polynomial function.
Also, LMT01-Q1 device is a high-accuracy, 2-pin temperature sensor with an easy-to-use pulse count current loop interface, which makes it suitable for onboard and off board applications in automotive.
Temperature switch: Many of TI’s automotive-qualified switches provide simple, reliable over-temperature warnings, for example TMP302-Q1.
But having the analog temperature value gives your system an early indicator that you can use to scale back to limited operation before getting to a critical temperature.
EV subsystems can also benefits from the programmable thresholds, ultra-wide operating temperature range and high reliability from in-circuit operational verification of theLM57-Q1due to the harsh operating environment (both ICs are available in AEC-Q100 Grade 0).
For complete portfolio of IC based temperature sensor parts, you can visit : http://www.ti.com/sensors/temperature-sensors/products.html
which provides digital pulse output over an isolation barrier.
are often used to monitor temperature, but their nonlinear temperature response can prove problematic for automotive solutions.
TI’s analog and digital temperature sensor solutions enable you to both accurately and easily monitor the temperature of many automotive systems.
About the Author
Mr.
MahendraPatel started his career in semiconductor industry with Texas Instruments 6 years ago.
As a field engineer, he supports multiple customer and application in automotive sector.
He enjoys working on designs related to Electric vehicles and automotive lighting.
interview/piyali-goswami-texas-instruments-application-engineer-shares-her-views-about-women-in-the-field-of-engineering-on-international-womens-day
Women in the Field of Engineering on International Women’s Day.
According to a Survey taken by Women’s Engineering Society in 2017, only 11% of the worlds engineering workforce are Women.
Surprising enough, another statistics from Joint Council for Qualifications, shows that girls normally out-perform boys in STEM (Science, Technology, Engineering and Math) subjects.
Then why don’t we just see more women Engineers in the field yet?
and she was generous enough to discuss the following with us.
I am a Software Applications engineer.
A typical day at office consists of working closely with ADAS customers to understand their system and software problems and offer optimal and innovative solutions to help them get the best out of TI devices.
The team here is very close and jovial.
Whether it is friendly banter, discussions (sometimes very passionate) on sports, opinions on the latest movie or spontaneous plans of eating out, there is always something fun and exciting to look forward to everyday.
The best part is we get to share the closeness even with our worldwide teams as the work and interactions span across the globe.
I have always been an engineer at heart.
Right from childhood, whether it be tinkering with electric switch boards at home or breaking apart electronic video games (not to the delight of my parents) to see what is in them, I have been curious to know how things work.
Over time, what I have come to love most about engineering is being able to come up with practical solutions to real world problems.
I love the whole process of breaking down a problem, coming up with ideas for the solution and transforming the idea from paper to reality.
The icing on the cake is to see your solution being deployed in the end equipment and knowing your ideas and work is improving the lives of many people.
I don’t believe Engineering is gender specific.
As long as one is passionate about making a difference, thoughts about being a girl or a boy should not matter.
I’ll be very honest, I did have some trouble with carpentry workshop back in B.Tech, but that’s about it!
is a technology which enables the driver of a vehicle with essential information and assistance with the aim of improving road safety.
ADAS technologies exist at different levels of active assistance.
Basic ADAS systems include driver information systems, like rear-view cameras, surround-view displays, and blind spot and lane departure warnings where the driver continues to remain in full control of the vehicle at all times.
Partially autonomous systems, such as lane keep assistance and active cruise control, enable the vehicle to control itself briefly in specific driving scenarios with the driver ready to override automatic control at all times.
Driver monitoring systems in addition keep track of the driver’s attentiveness.
Highly autonomous systems, including automatic parking valet, will take full control of the vehicle at specific times.
While self-driving cars are still in development, advanced driver assistance is with us today and rapidly increasing in importance.
family of devices.
The challenge was to understand from customers how to map the raw Radar data processing system requirements to TI devices, how different it is from vision/camera sensors and provide software solutions to enable meeting key criteria like processing latency, CPU load, configurability and functional safety.
Sensing the environment is a very critical task in ADAS and automated driving.
Sensors add intelligence to a vehicle and help create an accurate perception of the vehicle surrounding.
There are multiple image sensors in ADAS such as cameras, radar, laser, ultrasonic, infrared and Lidar.
Vision/Video cameras are one of the most popular and cost effective automotive sensors.
Front camera and surround view camera systems are critical vision-based systems that help drivers stay in their lanes, avoid collisions, keep pedestrians safe, and provide parking assistance.
Automotive radar sensors have the advantage of being able to penetrate nonmetal objects such as plastic, clothing and glass and is generally unaffected by environmental factors such as fog, rain, snow and bad or dazzling light.
Automotive radar systems are categorized as short-, mid- and long-range, based on the range of object detection.
Ultra-short range radar (USRR) is also an emerging ADAS application for park-assist systems.
Driver-assist features such as adaptive cruise control and automatic emergency braking use long range radar (LRR) systems.
Light detection and ranging (LIDAR) is a sensing method that detects objects and maps their distances for collision avoidance and 360 degree scene mapping.
LIDAR, radar, ultrasonic sensors and cameras have their own set of advantages and disadvantages.
Highly or fully autonomous vehicles typically use multiple sensor technologies to sense the environment under different weather and lighting conditions in order to increase redundancy and improve safety.
Sensor fusion is also deployed to generate an accurate and reliable map of the environment around a vehicle.
TI provides an environment which allows all employees to think and apply their creativity while solving problems in silicon design, test, software and systems.
There are experts in every domain of the semiconductor design, manufacturing and systems at TI.
The open culture allows anyone to walk up, discuss their ideas and learn from the experts within the organization.
In a technical discussion, there is no sense of hierarchy.
Whether you are a new college graduate or a senior technical leader, man or woman, everyone’s ideas are heard and considered on their technical merit.
At TI, there is a lot of emphasis and structure around developing, training and mentoring people at different stages of their career to help people realize their true potential and passion.
This shines through when senior leaders highlight this as a part of the organization’s priorities.
The timings are flexible to allow people to balance dedicating time towards their family and contribute at work.
It is up to an individual to set their boundaries to which they would like to explore and make an impact.
TI provides the opportunity for end to end ownership and rewards people accordingly.
TI also provides facilities and infrastructure to enable and encourage people to pursue their passions outside work, whether it is health and fitness (we have a gym, basketball, tennis courts within the campus), music, arts (there are classes organized regularly) or social initiatives to help give back to the society.
I believe for people who are driven, passionate about technology and want to make a difference in the world, the field of Engineering is a perfect place to create and express.
The kind of opportunities available in Engineering (and Semiconductors in particular) is growing exponentially with everything becoming more smart, connected and green ᾠAutomobile, Industry, Consumer‐here is no end.
There are many challenges yet to be solved to make these systems practical and cost effective.
There is now more opportunity than ever to build long fulfilling technical careers for both women and men.
When it comes to core engineering fields, there is often a skewed gender ratio starting from under Grad College.
This may be due to multiple reasons: social conditioning, preferences to which many women tend to gravitate towards, experiences and encouragement during one’s formative years.
Individuals at every stage of their career should be allowed to explore areas in which they feel excited, curious and passionate, and helped to take a decision either through counseling or coaching.
As an organization, it is very important to provide opportunities (especially to women) to work with flexibility with respect to time, identify areas of strength and interest, and coach them towards avenues which bring out their best and allow them to pace their careers.
I think the most important thing for any young engineer is to be curious and excited to learn.
Especially for young women engineers, it is important to seek mentors and people who can give you constructive feedback, guidance on career aspirations and confidence to step out of your comfort zone.
Network with other men/women senior engineers/managers to understand what their journey has been and what solutions they have applied to their hurdles.
Most times you would start seeing patterns and realize that any inhibitions or challenges are not unique to you or unsolved.
Most importantly have fun!
tutorial/hartley-oscillator
Hartley Oscillator
In simple terms, the oscillator is a circuit which converts DC power from the supply source to the AC power to the Load.
Oscillator system is built using both active and passive components and it is used for the production of sinusoidal or any other repetitive waveforms at the output without any application of an external input signal.
We discussed few oscillators in our previous tutorials:
Colpitts OscillatorRC Phase Shift OscillatorWein Bridge OscillatorQuartz Crystal OscillatorPhase Shift Oscillator CircuitVoltage Controlled Oscillator (VCO)
A simple oscillator application can be seen inside a very common device such as a watch.
Watches use an oscillator to produce a 1 Hz clock signal.
or any similar kind of wave across the output.
Other than the oscillator classifications based on the output signal, Oscillators can be classified using the circuit construction like negative Resistance oscillator, feedback oscillator etc.
The Tank Circuit
An LC oscillator consists of a tank circuit which is an essential part to produce the required oscillation.
The tank circuit is using three components, two inductors, and a capacitor.
The capacitor is connected in parallel with two series inductors.
Below is the circuit diagram of Harley Oscillator:
Because the LC circuit stores the frequency of the oscillation.
In the tank circuit, capacitor and two series inductors are being charged and discharged by each other repetitively which produce an oscillation.
The charge and discharge timing or in other words, the value of capacitor and inductors is the main determining factor for the oscillation frequency.
Transistor-based Hartley Oscillator
In the circuit, the output voltage appears across the tank circuit which is connected to the collector.
However, the feedback voltage is also a part of the output voltage which is denoted as V1, appearing across the Inductor L1.
Working of Hartley Oscillator Circuit
The active component in Hartley Oscillator is the transistor.
The DC operating point in the active region of the characteristics is governed by the resistors R1, R2, RE, and the collector supply voltage VCC.
The capacitor CB is the blocking capacitor and CE is Easter bypass capacitor.
In this configuration, the transistor input and output voltage have a 180-degree phase shift.
In the circuit, the output voltage V1 and the feedback voltage V2 has 180-degree phase shift.
By combing these two, we get a total 360 degree of phase shift, essential for the oscillation (referred to as Barkhausen criterion).
Another essential thing to start the oscillation inside the circuitry without applying an external signal is to produce noise voltage inside the circuit.
When the power is switched on, a noise voltage is produced with a wide noise spectrum and it has the required voltage component at the frequency, required for the oscillator.
The AC operation of the circuitry is not affected by the resistance R1 and R2 for a large resistance value.
These two resistors are used for the biasing of the transistor.
The earth and CE are being used for the immunity of overall circuit and these two resistors and capacitor are used as emitter resistor and emitter capacitor.
F = 1 / 2π√LTC
Op-Amp Based Hartley Oscillator
In the above image, the op-amp based Hartley oscillator has been shown where capacitor C1 is connected in parallel with L1 and L2 in series.
, where the resistor R1 and R2 is the feedback resistor.
The amplifier voltage gain can be determined by the below-mentioned formula ᾍ
A = - (R2 / R1)
The feedback voltage and the output voltage is also denoted in the above op-amp based Hartley oscillator circuit.
The frequency of the Oscillation can be calculated using the same formula which is used in transistor based Hartley oscillator section.
Hartley oscillator usually oscillates in the RF range.
The frequency can be varied by altering the value of inductor or capacitors or both.
For the selection of a variable component, capacitors are chosen above the inductors as they can be easily varied than inductors.
The frequency of the oscillation can be changed in the ratio of 3:1 for smooth variations.
Example of Hartley Oscillator
Suppose a Hartley oscillator with a variable frequency of 60-120 KHz consist of a trimmer capacitor (100 pF to 400 pF).
The tank circuit has two inductors where the value of one inductor is 39uH.
So to find the value of other inductor, we will follow the below procedure:
The frequency of Hartley oscillator is-
F = 1 / 2π√LTC
In this situation where the frequency varies between 60 to 120 kHz which is a 1:2 ratio.
The variation of the frequency can be obtained by a pair of coils since the capacitance varies in the ratio of 100pF: 400 pF which is a 1:4 ratio.
So, when the frequency F is 60 kHz, the capacitance is 400 pF.
Now,
So, the total capacitance is 17.6 mH and the value of other Inductor is
17.6 mH ᾠ0.039 mH = 17.56 mH.
Differences between Hartley Oscillator and Colpitts Oscillator
Advantages and Disadvantages of Hartley Oscillator
1.The Output amplitude is not proportional with the variable frequency range and the amplitude remains near constant.
2.Frequency is easily controllable using a trimmer instead of the fixed capacitor in the tank circuit.
3.Well suitable for RF range applications due to stable RF frequency generation.
1.Hartley Oscillator provides a distorted sine wave and not suitable for pure sine wave related operations.
The main reason for this drawback is the high amount of harmonics induced across the output.
2.In low frequency the Inductor value become large.
is mainly used to generate sine wave in various devices like Radio transmitter and receivers.
article/current-sensing-solutions-in-ev-hev-batteries
Current Sensing Solutions in EV/HEV Batteries
(BMS), precise and accurate current measurement is essential.
These high-voltage subsystems need to measure large currents at high common-mode voltages.
For technical and regulatory reasons, the current measurements require isolation as well as very high performance in harsh automotive environments.
The typical configurations of electric vehicles in India are as below:
Battery pack voltage = 48V , 72V
1kW , 2kW Motor
Battery pack voltage = 48V , 72V
2kW , 4kW Motor
Battery pack voltage = 72V , 400V , 600V
20kW to 300kW
One of the key features to make an electric vehicle safe is to collect data and take quick feedback actions locally based on this data.
One such data point which is very important and key to safety is the current flowing across various sub-systems of an electric vehicle.
broadly into 3 categories as shown below:
Traction drives :
Battery protection circuitry :
Battery gauging
System power consumption
Power steering
Motor drive application :
DC/DC converters
Below is a high level overview of the different solutions from TI for current sensing applications.
The Y axis is the common mode voltage of the rail through which current is being sensed and the X axis is the actual amplitude of the current being measured.
As shown in above figure current can be sensed through a voltage across a small shunt resistance or can be measured by measuring the magnetic field produced by the current while flowing through the conductor.
At Ti we provide solutions for measuring current using both the methods mentioned above.
A list of solutions available from TI for current sensing application can be seen below:
Lets look at each of the use cases of current sensor in a little more depth and look at some suitable solutions available from TI for the same.
1. Real time Over-current protection
This use case is generally seen in an EV from a safety prospective.
As the batteries can discharge huge amounts of current during occurrence of a fault, having real time fault monitoring circuitry becomes very important.
The speed and the accuracy of such a circuitry is the figure of merit the current sense amplifier.
In some occasions as the uC has limited bandwidth, sampling the analog current value ᾠconverting into a digital value followed by a digital value comparison to detect overcurrent causes a huge delay in the protection circuitry.
To tackle this problem TI has come up with current sense amplifier with integrated comparators whose threshold can be set and can be directly fed into the interrupt pin of the uC causing a huge reduction in overload of the uC.
Some of the solutions from TI for over current protection are:
A very good example of this use case is using a current sense amplifier as an E fuse as shown below:
2. Current and power monitoring for System optimization
Current and power monitoring is usually implemented in electric vehicle systems to monitor the total current consumption from the battery and thus giving real-time information to the driver about the charge left in the battery of the vehicle using algorithms like coulomb counting.
Besides the above use case current monitoring in vehicles Is utilized in different subsystems like the power steering, power windows and similar areas.
TI has a broad portfolio when it comes to current and power monitoring.
As mentioned above one of the key focus areas is to look into the current flowing in and out of the battery pack so as to count the coulombs and calculate the remaining battery life /charge.
TI’s INA299 stands out for such an application due to the high level of integrity coupled with high precision and low quiescent current consumption.
We can see a typical high level block diagram below of a BMS with the INA299.
For more details and whitepapers please visit on to the product folder of INA299 on ti.com.
3. Current measurement for closed loop circuits
Due to the presence of multiple voltages available in an Electric vehicle, one finds a whole lot of combination of buck and boost converters presents in the power supply tree.
Some of the very prominent power supply blocks in a typical Electric vehicle is the on board charger, BLDC (traction motor drivers), 48V to 12V converter etc.
As the control loop in all these high wattage power supply is exercised using a uC, measurement of high accuracy, low latency current becomes of prime importance to implement peak current control loops.
For such application current sensor with very high bandwidth is required to measure switching current , output current for the control to take quick actions .Another highlight of such current sensors which are used in controlling motor drives is the ability of the sensors to reject Common mode noise at high frequency ( PWM rejection ) .
For examples INA253 excels in this application with its industry leading 93db CMRR even @ 50khz.
Below is a typical schematic shown which is used for inline current sensing application
Texas Instruments offers best-in-class isolated amplifiers and isolated modulators that help achieve very accurate isolated current measurements over temperature when paired with high-precision shunts.
TI has come up with a new range of isolated current sense amplifiers named as the AMC series which help the designed measure current with high accuracy with an isolation barrier of to the tune of 2kVrms.
ᾠwhich shall help engineers learn how to maximize the performance achieved, when measuring current with a current sense amplifier.
This is a series of short videos, each addressing a different topic.
Overall the training shall be broken into Three Sections
The Basics
Understanding Error Sources
Advanced Topics
by following the link.
About the Authors
Mr.
Shreenidhi Patil is an analog application engineer in Texas Instruments who mainly focuses on Grid metering, upcoming EV market and EV charging stations.
Mr.
MahendraPatel started his career in semiconductor industry with Texas Instruments 6 years ago.
As a field engineer, he supports multiple customer and application in automotive sector.
He enjoys working on designs related to Electric vehicles and automotive lighting.
tutorial/dual-converter-working-types-and-modes
An Overview of Dual Converters
, follow the links.
These questions may arise and you will get the answer in this article.
It means that both the load voltage and load current become reversible.
How four-quadrant operation is possible in the dual converter? That we will see further in this article.
It is used for high-power applications.
Four Quadrant Operation in Dual Converter
voltage and current both positive.
voltage is positive and current is negative.
voltage and current both negative.
voltage is negative and current is positive.
operation, the energy transfers from the load to source.
and the power flow is from load to source.
Principle of the Dual Converter (Ideal Dual Converter)
To understand the principle of the dual converter, we assume that both converters are ideal.
It means that they produce pure DC output voltage, there is no ripple at the output terminals.
The simplified equivalent diagram of the dual converter is as shown in the below figure.
In the above circuit diagram, the converter is assumed as a controllable DC voltage source and it is connected in series with the diode.
The firing angle of the converters is regulated by a control circuit.
So, the DC voltages of both converters are equal in magnitude and opposite in polarity.
This makes possible to drive current in reverse direction through the load.
in the form of below equations.
EDC1 = EmaxCos1
EDC2 = EmaxCos2
is the firing angle of converter-1 and converter-2 respectively.
For, single-phase dual converter,
Emax = 2Em /π
For, three-phase dual converter,
Emax = 3↳Em /π
For, ideal converter,
EDC = EDC1 = -EDC2
EmaxCos1 = -EmaxCos2
Cos1 = -Cos2
Cos1 = Cos (180 - 2)
1 = 180 - 21 + 2= 180
will change in such a way that it will satisfy below graph.
Practical Dual Converter
between the converters and that will flow through the load.
1) Operation without circulating current
2) Operation with circulating current
1) Dual Converter Operation without Circulating Current
In this type of dual converter, only one converter is in conduction and another converter is temporarily blocked.
So, at a time one converter operates and the reactor is not required between the converters.
At a particular instant, let say converter-1 acts as a rectifier and supplying the load current.
At this instant, converter-2 is blocked by removing the firing angle.
For inversion operation, converter-1 is blocked and converter-2 is supplying the load current.
It ensures reliable operation of thyristors.
If converter-2 trigger before the converter-1 has completely turned off, a large amount of circulating current will flow between converters.
There are many control schemes to generate a firing angle for circulating current free operation of the dual converter.
These control schemes are designed to operate very sophisticated control systems.
Here, at a time only one converter is in conduction.
Therefore, it is possible to use only one firing angle unit.
A few basic schemes are listed below.
A) Converter selection by control signal polarity
B) Converter selection by load current polarity
C) Converter selection by both control voltage and load current
2) Dual Converter Operation with Circulating Current
= 180.
Let say the firing angle of converter-1 is 60 then firing angle of converter-2 must be maintained at 120.
In this operation, converter-1 will operate as a rectifier and converter-2 will operate as an inverter.
Thus, in this type of operation, at a time both converters are in conducting state.
If the load current is reversed, the converter which is operated as a rectifier is now operating as an inverter, while the converter which is operated as an inverter is now operating as a rectifier.
In this scheme, both converters conduct at the same time.
So, it requires two firing angle generator unit.
is that we can get smooth operation of the converter at the time of inversion.
Time response of the scheme is very fast.
The normal delay period is 10 to 20 msec in the case of circulating current free operation is eliminated.
is that, the size and cost of reactor high.
Because of the circulating current, the power factor and efficiency are low.
To handle the circulating current, the thyristors with high current ratings are required.
1) Single-Phase Dual Converter
The circuit diagram of the dual converter is shown in the below figure.
A separately excited DC motor is used as a load.
The DC terminals of both the converters are connected with the terminals of the armature winding.
Here, two single-phase full converters are connected back to back.
Both converters supply a common load.
The waveform of the single-phase dual converter is as shown in the below figure.
2) Three-Phase Dual Converter
The circuit diagram of the three-phase dual converter is as shown in the below figure.
Here, two three-phase converters are connected back to back.
The principle of operation is the same as a single-phase dual converter.
in high-power applications.
article/cell-balancing-techniques-and-how-to-use-them
Cell Balancing Techniques and How to Use Them
, when batteries are combined in series the voltage value gets added up.
For example when four lithium cells of 4.2V is connected in series the effective output voltage of the resulting battery pack will be 16.8V.
In this article we will learn more about cell balancing and also briefly about how to use them on the hardware and software level.
Why do we need Cell Balancing?
is maintained to be equal to achieve the maximum efficiency of the battery pack.
When different cells are combined together to form a battery pack it is always made sure that they are of the same chemistry and voltage value.
But once the pack is installed and subjected to charging and discharging the voltage values of the individual cells tends to vary due some reasons which we will discuss later.
This variation in voltage levels causes cell unbalancing which will lead to one of the following problems
Thermal Runaway
The worst thing that can happen is thermal runaway.
As we know lithium cells are very sensitive to overcharging and over discharging.
In a pack of four cells if one cell is 3.5V while the other are 3.2V the charge will charging all the cells together since they are in series and it will charge the 3.5V cell to more than recommended voltage since the other batteries are still require charging.
Cell Degradation
When a lithium cell is overcharged even slightly above its recommended value the efficiency and life cycle of the cell gets reduced.
For example a slight increase in charging voltage from 4.2V to 4.25V will degrade the battery faster by 30%.
So if cell balancing is not accurate even slight overcharging will reduce the battery life time.
Incomplete charging of Pack
As the batteries in a pack get older few cells might be weaker than its neighboring cells.
These week cells will be huge problem since they will charge and discharge faster than a normal healthy cell.
While charging a battery pack with series cells the charging process should be stopped even if one cell reaches the maximum voltage.
This way the if two cells in a battery pack get week they will charger faster and thus the remaining cells will not be charged to it maximum as shown below.
Incomplete use of Pack energy
the pack will be disconnected from load even if one cell reaches the minimum voltage.
This leads to the unused capacity of the pack energy as shown below.
Still there are few applications where initial cost should be very low and battery replacement is not a problem in those applications cell balancing could be avoided.
But in majority of applications including electric vehicles, cell balancing is mandatory to get the maximum juice from the battery pack.
What causes Cell unbalancing in battery packs?
Measuring the SOC of a cell is complicated; hence it is very complex to measure the SOC of individual cells in a battery.
An ideal cell balancing technique should match the cells of same SOC instead of the same voltage (OCV) levels.
But since it is practically not possible cells are matched only on voltage terms when making a pack, the variation in SOC might lead to change in OCV in due course.
It is very hard to find cells of the same Internal resistance (IR) and as the battery age the IR of the cell also get changed and thus in a battery pack not all cells will have the same IR.
As we know the IR contributes to the internal impedance of the cell which determines the current flowing though a cell.
Since the IR is varied the current through cell and its voltage also gets varied.
The charging and discharging capacity of the cell also depends on the temperature around it.
In a huge battery pack like in EVs or solar arrays the cells are distributed over a waste areas and there might be temperature difference among the pack itself causing one cell to charge or discharge faster than the remaining cells causing an imbalance.
There many different types of hardware and software techniques used for battery cell balancing.
Let is discuss the types and widely used techniques.
Types of Battery Cell Balancing
Cell balancing techniques can be broadly classified into the following the four categories which are listed below.
We will discuss about each category.
Passive Cell Balancing
Active Cell Balancing
Lossless Cell Balancing
Redox Shuttle
1. Passive Cell Balancing
Passive cell balancing method is the simplest method of all.
It can be used in places where cost and size are major constraints.
The following are the two types of passive cell balancing.
Each cell connected in series in a pack will have its own bypass resistor connected through a switch as shown below.
When mosfet is turned on that particular cell begins to discharge through the resistors.
Since we know the value of resistors we can predict how much charge is being dissipated by the cell.
The capacitor connected in parallel with the cell is used to filter voltage spikes during switching.
as shown below
The internal P-channel MOSFET will be triggered by the controller which causes the cell to discharge (I-bias) through the resistors R1 and R2.
The value of R2 is selected in such a way that the voltage drop occurring across it due to the flow of discharge current (I-bias) is enough to trigger the second N-channel MOSFET.
This voltage is called the gate source voltage (Vgs) and the current required to bias the MOSFET is called as biasing current (I-bias).
The value of this resistor can be low allowing more current to pass though it and thus discharging the battery faster.
This current is called as drain current (I-drain).
In this circuit the total discharge current is the sum of drain current and bias current.
When the P-channel MOSFET is turned off by the controller the biasing current is zero and thus the voltage Vgs also gets zero.
This turns off the N-channel MOSFET leaving the battery to get ideal again.
from renowned manufacturers like Linear and Texas instruments respectively.
These ICs can be cascaded to monitor multiple cells and saves development time and cost.
The charge Limiting method is the most inefficient method of all.
Here only the safety and life time of the battery is considered while giving up on the efficiency.
In this method the individual cell voltages are monitored continuously.
During the charging process even if one cell reaches the full charge voltage the charging is stopped leaving the other cells half the way.
Similarly during discharging even if one cell reaches the minimum cut-off voltage the battery pack is disconnected from the load until the pack the charged again.
Although this method is inefficient it reduces the cost and size requirements.
Hence it is used in an application where batteries could be often charged.
2. Active Cell Balancing
This is achieved by utilizing charge storing elements like Capacitors and Inductors.
There are many methods to perform Active cell balancing lets discuss the commonly used ones.
This method utilizes capacitors to transfer charge from high voltage cell to low voltage cell.
The capacitor is connected through SPDT switches initially the switch connects the capacitor to the high voltage cell and once the capacitor is charged the switch connects it to the low voltage cell where the charge from the capacitor flows into the cell.
Since the charge is shuttling between the cells this method is called as charge shuttles.
The below figure should help you understand better.
The below figure represents an Inductive converter with only two cells and single buck boost converter.
In the above circuit charge can be transferred from cell 1 to cell 2 by switching the MOSFETS sw1 and sw2 in the following manner.
First the switch SW1 is closed this will make the charge from cell 1 to flow into the inductor with current I-charge.
Once the inductor is fully charged the switch SW1 is opened and the switch sw2 is closed.
Now, the inductor which is fully charged will reverse its polarity and begin to discharge.
This time the charge form the inductor flows into the cell2 with current I-discharge.
Once the inductor is fully discharged the switch sw2 is opened and the switch sw1 is closed to repeat the process.
The below waveforms will help you get a clear picture.
During the time t0 the switch sw1 is closed (turned on) which leads to the current I charge to increase and the voltage across inductor (VL) to increase.
Then once the inductor is fully charged at time t1 the switch sw1 is opened (turned off) which makes the inductor to discharge the charge that it accumulated in previous step.
When a inductor discharges it changes its polarity hence the voltage VL is shown in negative.
When discharging the discharge current (I discharge) decrease from its maximum value.
All this current enters the cell 2 to charge it up.
A small interval is allowed from time t2 to t3 and then at t3 the whole cycle repeats again.
This method also suffers from a major disadvantage that charge could be transferred only from higher cell to lower cell.
Also the loss in switching and diode voltage drop should be considered.
But it is faster and efficient than the capacitor method.
As we discussed the buck boost converter method could only transfer charges form the higher cell to the lower cell.
This problem can be avoided by using a Fly back converter and a transformer.
In a flyback type converter the primary side of the winding is connected to the battery pack and the secondary side is connected to each individual cell of the battery pack as shown below
As we know the battery operates with DC and the transformer will have no effect until the voltage is switched.
So to begin the charging process the switch on the primary coil side Sp is switched.
This converts DC to pulsed DC and the transformer primary side is activated.
Now on the secondary side each cell has its own switch and the secondary coil.
By switching the mosfet of the low voltage cell we can make that particular coil to act as a secondary for the transformer.
This way the charge form the primary coil is transferred to the secondary coil.
This causes the overall battery pack voltage to discharge into the weak cell.
and not particular cell is discharges.
But since in involves a transformer, it occupies a large space and the complexity of the circuit is high.
3. Lossless balancing
Lossless balancing is a recently developed method that reduces losses by reducing the hardware components and providing more software control.
This also makes the system simpler and more easier to design.
This method uses a matrix switching circuit which provides the capability to add or remove a cell from a pack during charging and discharging.
A simple matrix switching circuit for eight cells is shown below.
During charging process the cell which is of high voltage will be removed from the pack using the switch arrangements.
In the above figure the cell 5 is removed from the pack by using the switches.
Consider the red line circles to be open switches and the blue line circle to be closed switches.
Thus the rest time of the weaker cells are increased during the charging process so as to balance them during charging.
But the charging voltage has to be adjusted accordingly.
The same technique can be followed during discharging also.
4. Redox Shuttle
The final method is not for hardware designers but for chemical engineers.
In lead acid battery we do not have the problem of cell balancing because when a lead acid battery is overcharged it causes gassing which prevents it from getting over charged.
The idea behind Redox shuttle is to try achieving the same effect on lithium cells by altering the chemistry of the electrolyte of the lithium cell.
This modified electrolyte should prevent the cell from getting overcharged.
An effective cell balancing technique should combine the hardware to a proper algorithm.
There are many algorithms for cell balancing and it depends on the hardware design.
But the types can be boiled down to two different sections.
This is the easy and most commonly followed method.
Here the open cell voltages are measured for each cell and cell balancing circuit works to equalize the voltage values of all the cells connected in series.
It is simple to measure OCV (Open circuit voltage) and hence the complexity of this algorithm is less.
In this method the SOC of the cells are balanced.
As we already know measuring the SOC of a cell is a complex task since we have to account in the voltage and current value of the cell over a period of time to calculate the value of SOC.
This algorithm is complex and used in places where high efficiency and safety is required like in aerospace and space industries.
This concludes the article here.
Hope now you got a brief idea of what cell balancing is how it is implemented in hardware and software level.
If you have any ideas or techniques do share them in the comment section or use the forums to get technical help.
tutorial/colpitts-oscillator
Colpitts Oscillator
An oscillator is a mechanical or electronic construction which produces oscillation depending on few variables.
We all have devices which need oscillators like a traditional clockor a wristwatch.
Various types of metal detectors, computers where microcontroller and microprocessors are involved use oscillators, especially electronics oscillator which produces periodic signals.
We discussed few oscillators in our previous tutorials:
RC Phase Shift OscillatorWein Bridge OscillatorQuartz Crystal OscillatorPhase Shift Oscillator CircuitVoltage Controlled Oscillator (VCO)
by forming an LC filter.
Same as other oscillators Colpitts oscillator consists of a gain device, and the output is connected with an LC circuit feedback loop.
The Colpitts oscillator is a linear oscillator which produces a sinusoidal waveform.
The Tank Circuit
consists of three components- a inductor and two capacitors.
Two capacitors are connected in series, and these capacitors are further connected in parallel with inductor.
The oscillation is highly depended on the capacitors and the inductor’s value.
Below formula is to determine the oscillation frequency:
F = 1 / 2π√LC
where F is frequency and L is Inductor, C is the total equivalent capacitance.
The equivalent capacitance of the two capacitors can be determined using
C = (C1 x C2) / (C1 + C2)
Transistors Based Colpitts Oscillator
T1.
is used as an emitter bypass capacitor which is connected in parallel with the resistor R3.
If we remove this C3 capacitor, the amplified AC signal will be dumped across resistor R3 and results in a poor gain.
So, the capacitor C3 is provided an easy path for the amplified signal.
The feedback from the tank circuit is further connected using the C4 to the transistor T1's base.
, the loop gain should be slightly greater than the unity and the phase shift around the loop needs to be 360 degrees or 0 degrees.
So, during this case, to provide the oscillation across the output, the total circuit needs 0 degrees or 360-degree phase shift.
The transistor configuration as common emitter provides 180-degree phase shift whereas the tank circuit also contributes an additional 180-degree phase shift.
By combining this two-phase shifts the total circuitry achieves 360-degree phase shift which is responsible for the oscillation.
which is further fed back to the tank circuit.
The determination of the feedback voltage is a crucial part of the circuitry because the low amount of feedback voltage would not activate the oscillation whereas a high amount of feedback voltage will end up in destroying the output sine wave and induce distortion.
There are two ways to make the Colpitts oscillator work in a variable tuning configuration.
In the second option, as the feedback voltage is highly dependable on the ratio of C1 and C2 it is advisable to use a simple gang.
So that when there is variation in one capacitor the other capacitor also changes its capacitance in accordance with it.
Op-Amp Based Colpitts Oscillator
Resistors R1 and R2 are used due to provide the necessary feedback to the operational amplifier.
The tank circuit is connected along with the single inductor in parallel with two series capacitors.
The input of the operational amplifier is connected to the feedback of the tank circuit.
Difference between Colpitts Oscillator and Hartley Oscillator
Colpitts oscillator performs more stable in high-frequency operation than the Hartley Oscillator.
The Colpitts oscillator is an excellent choice in high-frequency operation.
It can produce output frequency in Megahertz range as well as in Kilohertz range.
Application of Colpitts Oscillator Circuit
1. Due to the difficulties in a smooth variation of inductor and capacitor, the Colpitts oscillator is mainly used for fixed frequency generation.
2. The main use of Colpitts oscillator is in mobile or other radio frequency controlled communications devices.
3. In high-frequency oscillation, Colpitts oscillator is an excellent choice.
Thus high-frequency oscillator based devices use Colpitts Oscillator.
4. In a few applications where continuous and undamped oscillation is needed in addition with thermal stability, Colpitts Oscillator is used.
5. For those applications which need a wide range of frequencies with minimum noise induced.
6. Many types of SAW-based sensors use Colpitts oscillator
7. Various types of metal detector use the Colpitts oscillator.
8. Frequency modulation related radio frequency transmitter use Colpitts oscillator.
9. It has a huge application in military and commercial grade products.
10. In microwave applications, signal masking related chaotic circuits is also required Colpitts oscillator in the different frequency range.
article/implementing-low-power-consumption-in-microcontrollers
Minimizing Power Consumption in Microcontrollers
Just as gas (petrol/diesel) is important for bikes, trucks and cars (yeah, excluding Teslas!) to move, so is electric power for most of the electronics applications and more so, for embedded system based applications which are usually battery (limited energy) powered, from the regular mobile phones to smart home devices amongst others.
The Limited nature of battery power implies the need to ensure the rate of power consumption of these devices should be reasonable to encourage their adoption and use.
Especially with IoT based devices where a device could be expected to last for as long as 8 ᾠ10 years on a single charge without battery replacement.
Power Saving Techniques for Microcontrollers
1. Sleep Modes
Depending on the architecture and manufacturer, microcontrollers usually have different kind of sleep modes, with each mode possessing the ability to disable more internal circuitry or peripheral compared to the other.
Sleep modes usually range from deep sleep or off, to idle and doze modes.
It should be noted that the characteristics as well as name of these modes may vary from manufacturer to manufacturer.
With this, the CPU is able to resume operations immediately the wake-up trigger is activated.
Clock gating has been employed extensively to cut off signals in low power modes for microcontrollers and this mode effectively gates clock signals across the CPU.
, but one major difference is it allows change in the content of the ram which is not usually the case with the idle/sleep mode.
In Standby mode, high-speed peripherals like the DMA (direct memory access), Serial Ports, ADC and AES peripherals are kept running to ensure they are available immediately after the CPU is awake.
For certain MCUs, the RAM is also kept active and can be accessed by the DMA allowing data to be stored and received without CPU intervention.
Power drawn in this mode can be as low as 50uA/MHZ for low power microcontrollers.
used to drive critical elements like the watchdog timer, brown out detection and the power on reset circuitry.
Other MCUs may add other elements to it to improve the overall efficiency.
Power consumption in this mode can be as low as 1uA depending on the particular MCU.
without making compromises that affects the specification of the system.
2. Dynamic Modification of Processor Frequency
as the relationship between the frequency of the processor and the amount of power consumed is linear (as shown below).
The implementation of this technique usually follows this pattern; when the system is in an idle state, the firmware sets the clock frequency to a low speed allowing the device to save some power and when the system needs to do heavy computations, the clock speed is brought back up.
There are counterproductive scenarios to modifying processor frequency which is usually as a result of badly developed firmware.
Such scenarios arise when the clock frequency is kept at a low while the system is performing heavy computations.
A low frequency in this scenario means the system will take more time than necessary to perform the set task and will thus accumulatively consume the same amount of power the designers were trying to save.
Thus, extra care must be taken when implementing this technique in time critical applications.
3. Interrupt Handler Firmware Structure
It is made possible by few microcontrollers like, the ARM cortex-M cores which have a sleep-on-exit bit in the SCR register.
This bit provides the microcontroller with the ability to sleep after running an interrupt routine.
While there is a limit to the number of applications that will run smoothly in this manner, this could be a very useful technique for field sensors and other, long-term, data gathering based applications.
and may not be very beginner friendly.
4. Power Optimized Firmware
This directly affects the amount of work done by the CPU per time and this, by extension contributes to the amount of power consumed by the microcontroller.
Efforts should be made while writing the firmware to ensure reduced code size and cycles as every unnecessary instruction executed, is a portion of the energy stored in the battery being wasted.
Below are some common C based tips for optimized firmware development;
Use the “Static ConstᾠClass as much as possible to prevent runtime copying of arrays, structures etc.
that consumes power.
Use Pointers.
They are probably the most difficult part of the C language to understand for beginners but they are the best for accessing structures and unions efficiently.
Avoid Modulo!
Local variables over global variables where possible.
Local variables are contained in the CPU while global variables are stored in the RAM, the CPU accesses local variables faster.
Unsigned data types are your best friend where possible.
Adopt “countdownᾠfor loops where possible.
Instead of bit fields for unsigned integers, use bit masks.
, exist, but to keep the length of this post within a reasonable range, we will save them for another day.
Conclusion
that are available for use during the low power modes.
tutorial/harmonic-filter-circuit-how-to-remove-harmonics-using-active-and-passive-harmonic-filters
Harmonic Filter Circuit: How to remove Harmonics using Active and Passive Harmonic Filters
What is Harmonics in Electrical System?
induced by the non-linear load such as VSDs (variable speed drives).
The nonlinear loads draw current from the power line that is not in a perfect sinusoidal waveform.
The nonsinusoidal current waveform can be a complex series of simple sinusoidal which can oscillate at an integer, multiple of the power line fundamental frequency.
are caused by the current harmonics.
The Voltage harmonic occurs because of the distorted voltage produced by the effect of current harmonics with the source impedance.
The above image shows the distressed current waveform across the non-linear load.
Here the distorted current waveform is not following the sinusoidal wave.
This shows the current harmonics in the power system.
Why it is necessary to eliminate Harmonics in the Power System?
Current and the voltage harmonics are directly proportional to the noisy power transfer to the Load.
Various household and office equipment are responsible for the harmonics in the power system.
The power system harmonics often increase the load current.
Various instruments, like Fluorescent lights in the factories or in the house or office, are affected by harmonics and suffer from various malfunctions.
Motors are hugely affected by the power system harmonics.
Sometimes the harmonics in the power systems can be very dangerous and increase power delivered to the instruments which leads to a temperature rise in the Load and can shorten the instrument life.
Type of Harmonics Filters
Harmonics filters very effective to protect costly electrical equipment from distorted power outputs due to harmonics.
There are different types of harmonics filters available in the electrical and electronics market depending on the rated power, applied voltage, single phase or three phases and other load-dependent parameters.
and integrated circuits.
As the harmonics filters are the electrical line safety equipment they must confirm the international safety standards like IEEE, EN, AS, BS and the underwriter's laboratories UL mark.
Also, the harmonics filters can be designed in different orders.
Like a third order harmonic filters can filter out the frequency which is the third multiple of the fundamental frequency.
Passive Harmonic Filters
Passive harmonic filters are the most common and the easily available harmonic filter.
It is affordable filter to suppress the harmonic disturbance in the power line.
The filter can be tuned to a certain frequency that needs to be eliminated as harmonics.
are used:
1. High pass filter
2. Bandpass filter
3. C type filter and
4. Series filter.
High pass passive harmonic filters are used to eliminate higher order harmonics and to have flexible control over the wide range of frequencies.
The basic high pass harmonic filter design use three passive components, resistor, capacitor, and inductor.
In the above image, we can see the basic construction of a passive high pass harmonic filter.
The construction shows the resistor and the inductor is in parallel connection a capacitor in series.
The filter produces flat impedance characteristics in the high-frequency range.
The high frequency decreases the power loss.
/ 6th or higher order current.
Often different filters are combined with high pass harmonic filters to eliminate power loss when used in low order or low-frequency applications.
The impedance curve with the frequency can be shown in the below image.
It is also used for high order harmonic filtration purposes.
This filter works with the combining parallel resonance of the standard bandpass filter along with series resonance of inductor and capacitor combined.
a resistor, an inductor, and a capacitor are connected in parallel.
The first part and the second part are also connected in series.
The impedance characteristics with the frequency can be shown in the below graph.
C type filter is used for the low order such as second or third order harmonic filtration purposes.
C type filters have lower loss than the equivalent bandpass or the series filter.
In the above image, the basic construction of c type filter is shown.
A capacitor is connected in series of an inductor which is again connected in parallel with the resistor.
The three component parallel connection is again connected in series with a second capacitor.
The resistor suppresses the fundamental current created by the oscillated inductor and capacitor.
The Impedance curve is shown in the below image-
This filter eliminates single frequency.
The construction of this filter can be shown in the below image where 3 passive components are connected in series to form the single tuned series harmonic filter.
The Impedance characteristic is shown in the below image -
Active Harmonic Filters
As discussed previously, passive harmonics filters are good to eliminate harmonics associated in the power line.
However, the passive harmonic filter design is really complex and the designer must design the passive harmonic filters in accordance with the reactive power requirements of the load.
In such a case, the passive filter design is very difficult and it leads to a poor power factor operation for certain load conditions.
Active harmonic filters use an excellent method where the filter use self-produced harmonic components and injects this to the power line which cancels the unwanted harmonics.
which use different topologies to eliminate the harmonics in the power line.
The most common active harmonic filters design uses the following basic things like
1.Voltage source inverter using various power switches
2.Sampling and control reference from the power line
3.PWM system which injects PWM firing pulse into the system as harmonics.
The Active Harmonic filter uses a different kind of semiconductor switches which requires power to operate.
How to select Harmonic Filters
at which the filters need to be tuned.
In a few cases, the filter operation is failed to serve the purpose just because of wrong tuning at a certain fundamental frequency where no harmonics are present.
and depending on the harmonic order the filter need to be chosen.
To eliminate single frequency harmonic distortion series harmonic filters are efficient but in few cases double tuned harmonics filters need to be employed.
also need to be compensated which are highly dependent on the choice of filter.
Sometimes for a high level of nonlinear loads, active and passive both types of harmonic filters are required.
interview/jagatheeswaran-head-of-innovation-and-technology-shares-how-he-develops-solutions-for-industry-40-and-iot-applications
Jagatheeswaran Senthilvelan Head of Innovation and Technology shares how he develops solutions for Industry 4.0 and other IoT applications
He has been involved in the development of various end to end IoT solutions; one such example is to measure and manage the water infrastructure at Titan Industries (Hosur) using IoT and completely handled the deployment and commissioning from client’s facility.
He has also been the Tech Coordinator for Cisco LaunchPad Cohort 3, which is an Elite Startup Accelerator program which will be held for 6 months annually in India where the top 8 startups in India will be selected.
Currently, he is focusing on Protogen which is is the academic wing of FluxGen Engineering Technologies Pvt.Ltd.
ProtoGen provides products and services to build a solid foundation and familiarize learners with current trends in technology.
Excited by his works, we were curious to know more.
So we approached him with few questions, and he was generous to provide us the following answers.
FluxGen Engineering Technologies is on a dutiful mission to help mitigate water and energy crisis across the globe by deploying state-of-the-art solutions in water and energy monitoring and management by providing cost-effective Internet of Things (IoT) solutions to identify consumption pattern and reduce the expenditure.
across the business value chain.
According to IBEF, the Government of India plans to increase the contribution of manufacturing sector to 25% of Gross Domestic Product (GDP) by 2025, from the current level of 16%.
India is also prepared to face global competition by undertaking the Make in India programme.
It is all set to lead the world with Smart Manufacturing.
Adopting Smart manufacturing, analytics and IoT will give a new lease of life to industrialization in India.
Apart from policy implementation hurdles, one major bottleneck is the fear of job losses owing to Robotics & Automation.
A smart strategy to counter this is to upskill workers and millennials in these fields and create a quality workforce.
This lead to Starting-up Protogen.
Protogen is unique from others in a way that we bridge the gap between the academia and the industry by imparting our knowledge and experience directly from the industry with cutting-edge technologies.
We have impacted more than 5000 students and 1000 professionals by partnering with more than 15 industries to upskill the future workforce.
We have conducted more than 100 training programmes covering a wide range of technology to build confidence, knowledge and skills among the participants to build their own product prototypes and set up their own startup.
Define your main goal of the project.
Start your initial brainstorming with your team.
You may know your design obstacles and need to research solutions.
Stick with 1 or 2 features, to begin with.
Remember this version will be refined along the way.
Create your design on paper.
Discuss with appropriate partners or stakeholders knowing there will be improvements.
Any managers, users, researchers etc.
should be included for feedback.
Edit your design after discussion with partners or stakeholders.
Design from paper to prototype with the top three features of the product which you are planning to make.
Keep it very simple.
Don't strive for perfection.
The user is encouraged to work with the system in order to determine how well the prototype meets his or her needs and to make suggestions for improving the prototype.
Note down all the changes the user requests and refine the prototype accordingly.
After the prototype has been revised, the cycle returns to (3).
(3) And (4) are repeated until the user is satisfied.
Recently we had conducted one survey on “How to increase the innovation coefficient of Engineering studentsᾬ in that we had asked this question to them
”What is the most challenging part of Product Development?ᾠOption are:
Coming up with a new idea
The Idea to Prototype
Prototype to Product
The survey was taken by around 500 students.
The results were amazing around 47% of the students told idea to prototype is the most challenging part and around 29% of the students told coming up with a new idea is the most challenging.
Remaining 24% told prototype to product.
So from this, we found the most challenging part is the idea to prototype and coming with the new idea.
To tackle this we designed a ProtoShop “Prototyping Workshopᾠwith Both Technical and Design Thinking assignments.
And with this ProtoShop till now we have successfully trained around 3000+ students and out of which around 30+ prototypes have come out and few of them won YUStart Awards by CII, Bangalore
Initial Prototype doesn’t require a sophisticated enclosure design.
Best thing I would suggest is there are ready-made enclosures with different IP standards in the market with good aesthetics and also available in different sizes.
One can get that and make their product prototype.
I will suggest this even for selling it to the early stage customers.
Once the product is frozen and ready to market in scale one can go for special design for their product.
Arduino is all time favorite for all those who start with a Prototype design, even for me the same because of its ease to use and it is open source.
Along with Arduino raspberry pi is also an amazing product to start prototyping with.
And I know few successful startups with raspberry pi and Arduino as their core hardware platform.
For getting started with IoT prototyping I would suggest NodeMCU, it is development board with ESP8266 WiFi SoC on it.
And NodeMCU also has a lot of tutorials available on the internet
The ProtoKit is an Arduino -IDE compatible development platform that enables quick--and--easy product prototyping.
It can interact with real--world sensors, control motors, display information, and perform near--instantaneous calculations.
It enables anyone to create unique, mind-blowing projects.
The ProtoKit also serves as an excellent physical computing learning platform.
We’ve designed the IoT Node to be as easy--to--use as possible.
It can be used to help teach both programming and electronics concurrently ᾠtwo skills that are becoming significantly important in today’s high--tech world.
It comes with integrity with 5 Wireless Technologies namely: Bluetooth, ZigBee, LoRa, WiFi, GSM.
I personally think Firebase and Adafruit.io is the best cloud service for prototype development because it is open source and a lot of source codes and tutorials are available for this.
And they have very good support in terms of APIs for cross-platform integration like Android, IOS, Web-based apps., etc.
There are various parameters to select one among them, it will always be based on the Application for which they are using it.
First one has to decide on the Product/ Application and then select them based on following parameters like:
Power Consumption of their product (For Low Power Consumption Probably LoRa/ Ble would be best not WiFi/GSM/ZigBee)
Cost
Signal Range
Frequency Range
Number of devices connected at a time
Data Transfer Rate ., etc
Lack of awareness of the current trends in the industry and courage to pursue their interest is where our engineers lag today.
There is a process set already by the education system which drives most of the engineers today to the monotonous jobs, and also they have fear of failure and self-doubt on their career vision.
To overcome this they have to keep them updated and aware of what's happening in and around the world.
How much ever the engineers are desperate to find jobs, the companies are even more desperate to find the right talent.
There are a lot of opportunities available around the world, engineers have to go and grab it.
Prototyping is one of the most essential skills in this generation.
Let it be fixing your table or building your own system at home to wake yourself up in the morning.
It doesn't matter if you are an innovator, an engineering student, an entrepreneur or someone with an idea that could help solve the planets greatest of problems.
An Idea alone cannot take you the distance, but quickly building it and showing out to the world that your idea really works and has the potential to become something is what matters.
This program will give you a head start into the world of Product Prototype development with a specialization in IoT and embedded systems products.
The course will be conducted by practising engineers in IoT with field deployment experience who also have research publications in top International journals and conferences.
The similar workshop has been conducted for Google Product Managers from Mountain View, Accenture Strategy Team, Karlsruhe Institute of Technology Germany, VU University Amsterdam, Indian Institute of Science, National Institute of Technology Surathkal and others
tutorial/what-is-diac-construction-working-and-applications-in-triggering-the-triac
What is DIAC: Construction, Working and Application in Triggering the TRIAC
is shown.
Construction of DIAC
without the gate terminal.
In the above image, Three N-type regions are shown with the name of NA, NB, and NC.
P-type regions are shown as PA and PB.
If MT1 terminal became more positive than MT2, the current will flow in the direction of PA -> NB -> PB -> NC.
When the reverse situation occurs, the MT2 terminal became more positive than the MT1 and the current will flow in a direction of PB -> NB -> PA -> NA.
.
As DIAC is a bidirectional device, it will happen for both directions of the current.
DIAC Characteristic Curve
In the above image, the actual I-V characteristic of DIAC is shown.
The curve looks like the English word Z.
The DIAC remains in the nonconductive state until the breakdown voltage is reached.
The slow curve before going to the straight line is due to the leakage current.
After the breakdown voltage is reached, the DIAC enters into the low resistance state and the current flow through the diode is rapidly increased which is shown as a straight line.
But during the current conducting state the voltage drop across the diode is reduced, hence the line is not perfect 90 degrees.
DIAC Applications
, as the DIAC conducts in both directions.
TRIAC do not fire symmetrically and because of this, TRIAC do not trigger at the same gate voltage level for one polarity as for the other one.
This leads to an undesirable result.
The unsymmetrical firing results in a current waveform which has a greater variety of harmonic frequencies leads to uncertain possibilities inside the Power circuit.
To recover from this situation and to reduce the harmonic contents in a power system, DIAC is placed in series with the gate of a TRIAC.
Basic DIAC application is shown in the below image where the DIAC is being used as a triggering device of the TRIAC.
The DIAC is connected in series with the gate of a TRIAC.
The DIAC do not allow any gate current until the triggering voltage has reached to a certain repeatable level in both directions.
In this case, the firing point of the TRIAC from one-half cycle to the next half cycle tends to be more consistent and it reduces the total harmonic content of the system.
Practical Example of DIAC
The construction is fairly simple, it consists two 1N4007 diode which is a 1000V 1A rectifier diode and a 47uF capacitor with at least 300V rating.
For the DIAC, DB3, DB4 or NTE6408 can be used.
Two resistors of 20k and 100 Ohms ( Watt) are used along with a blue color standard LED, (3v)
Here two diodes are used for safety purpose which convert AC into DC.
Capacitor quickly gets charged by the diodes, and as soon as the charged voltage reaches DIAC‘s breakdown voltage, it starts to conduct and turn on the LED.
After turning on the LED and while the current is passing through the DIAC, the voltage drop decreases and the capacitor star discharging through the resistor 20k.
Turn on and off time of the LED can be controlled by changing the capacitor value.
In the below, the simulation is shown in Proteus.
The Quadrac construction
which uses DIAC and TRIAC in a single package.
In this device, DIAC is used to internally trigger the TRIAC.
Quadrac has a wide range of applications like switching, temperature modulation control, Speed control or various dimmer related applications.
interview/evi-technologies-aditya-raj-verma-speaks-on-ev-charging-stations-in-india
EVI Technologies Technical Director, Aditya Raj Verma speaks on Electric Vehicle charging stations in India
According to the BNEF forecasts, the growth of EVs in India is slow because of the shortage of charging infrastructure and lack of affordable models.
The growing market of EV, demands quality charging stations across the city to support daily commute of EV users and EVI Technologies is doing exactly that.
while you enjoy their conveniences.
The charging stations could function completely remote through a mobile application, using which the user can turn on the charger by making the payment online.
The charger then obtains the information about the users EV through CAN protocol and implements a suitable algorithm to charge EV accordingly.
A single charging station could charge upto three Vehicles simultaneously and could also leverage Solar energy if feasible.
Inspired by this futuristic charging station, we approached Mr.Aditya Raj who is the Technical Director and Cofounder of EVI Technologies to know more about the charging stations and he was kind enough to give us the following answers.
It all started in Augᾲ016 in my IIT hostel room.
Delhi AQI was oscillating between hazardous and severely unhealthy, while we were searching for efficient green ideas.
We narrowed it down to solar PV or electric vehicle.
Solar PV was a matured technology and further invention or innovation required developing efficient PV cells which involved heavy R&D and cost extensive infrastructure.
Electric vehicle was still untapped region in Indian market but designing vehicle was still expensive hence we thought on building supporting framework i.e.
charging infrastructure.
Also the Founding members of EVI technologies came from domain of electrical, electronics, mechanical and power with good hands on industrial experience.
Everything seems to be in sync hence we started working on design and development of a charging station.
EVI Technologies is currently floating four type of EV charging unit in its product basket
- It is 10kW system capable of charging 3 vehicle simultaneously with 3 phase input requirement.
It is designed as per AC001 standard.
We have supplied 50nos to government of India in its first tender.
- It is single phase 12kW level 2 ac charging unit designed with consideration for easy to install with less space requirement.
Further it features smart card mode of authorisation for easy to operate.
The system is capable delivering 60 amps of continuous current enabling fast charging feature
ᾠThis unit is designed to cater all kind of EV currently running on Indian roads with feature of AC as well as DC charging point.
The design has a smaller form factor and wall or pedestal mounting feature
ᾠThis is dedicated high power DC charging unit with power rating upto 20kW delivering 200 amps of DC current.
Further it feature communication port as per DC001 standards for EV BMS to charger communication.
The input is 3 phase is capable of fast charging 1 electric car or 3 electric 3 wheeler simultaneously.
The development took around 9 months for first prototype as we were fortunate to be selected under MeitY programme which provided power lab facilities with tools and test benches which saved a good amount of time.
Our EV AC Charging both 1 and 3 sockets can cater all kind of Electric vehicle i.e.
2 wheeler, 3 wheeler and 4 wheelers.
EVI Technologies EV AC charging 3 socket currently installed at Ministry of Power Complex, New Delhi is delivering energy to Mahindra Verito and Tata Tigor EV, the Indian EV variants running on roads.
AC/DC combo charger can also charge 3W, 2W, 4W over AC point and fast charge 3W,2W over DC point.
EVI’s DC charging unit is capable of fast charging 2W, 3W, 4W with maximum DC power delivery of 20kW.
Just to brief it up in bullets are as follows:
Should have a basic EV charging installation infrastructure i.e.
land, commercial electricity connection (EVI can support on revised tariff rate and new connection) and resources.
Site survey is done by EVI Technologies
Should install a minimum number of chargers (number is decided on what product franchise has chosen)
EVI can co-invest in setting up the EV charging unit with revenue sharing model
A token of security deposit is received in advance by EVI Technologies as per formal agreement.
The general misconception prevailing in market is EV charger must be faster or else it is not worthy.
The fast charging is function of battery chemistry and independent of charger applied.
If ‘xᾠkWh battery is connected to ᾴxᾠkW charger.
In case where battery can absorb ᾴxᾠkW charger can charge the battery full in 15 minutes.
But battery commercially used for EV support maximum of ‘x/2ᾠkW hence even with high rated charger the time for complete charge shoots to 2 hours.
EVI DC charging units are developed with SiC based power MOSFETs achieving efficiency over 96% at loading capacity window of (30-98%) as compared to existing charger provided by manufacturer i.e.
just 80% efficient at only 90% loading capacity.
Further onboard rectifiers on EV 4W have lower power rating and efficiency at that form factor slowing charge rate where as EVI DC charging unit provide higher efficient DC power accelerating charge rate
Open Charge Point Protocol is an open source protocol for communication between EV Charging unit and Central Server.
It was developed by E-Laad group in Netherlands with an aim to build an open application protocol that can be used by any EV charging manufacturer without worrying on server vendor.
The purpose of implementing OCPP is the single time development for EV charging manufacture with support to all kinds of EV charger variants across globe.
OCPP enables creation of a large-scale, visible network that uses a range of different charging with single application protocol scheme
For EV AC charging unit it is rated at 12 kW with maximum current delivering capacity of 60amps of continuous charge current.
As per global standards this charger falls in category of level 2- fast AC charging unit
For EV DC charging unit we have 20kW rated charger delivering 100Vdc and 210A dc for charging EV 4W over fast charging port
As per current statistics major metros like Delhi, Kolkata, Lucknow, Kanpur, Patna have significantly higher number of EV running on roads.
These locations are suits a good demand of building network of EV charging network.
Fortunately EVIT’s has already installed charger in majority of these cities.
Further tier 2 cities like Raipur, Bhopal are also have good rise in EV count and EVI has already installed charger and planning to expand network for infusion of more EV on roads.
The requirement of EV charging unit is direct function of EV’s on roads and with better charging infrastructure people choices can be inclined towards EV based travel.
Therefore it’s vice versa too i.e.
EV on roads is direct function of EV chargers available
The team is good mix of engineers from major streams of engineering with industrial experience and passionate character.
Further founder members are batch mates shared same campus and have strong bonding and better coordination.
Attached below is glimpse of team of EVI
As EVI technologies work culture is flexible and lively.
Interactions and appreciations are prime principle of EVI enabling it to perform and achieve in such s short span of time.
As a start up we believe in building cost effective products to carter our customer and team is always willing to customize designs to suit client’s requirement.
To brief on challenges we faced in developing our charger:
There were no Indian standards available for charger architecture and power ratings.
In Decᾲ017 first draft was rolled by ARAI as AIS138 but still no fixed standard protocols or design requirements
There is no standard charging coupler used by EV on Indian roads making difficult to design charger coupling socket
Component procurement and technical support was sluggish increasing product development time and cost
The challenge in sourcing components from manufacture was difficult because of MOQ and lead times.
We coordinate with third party distributor to procure the required components which incurs additional cost and increasing development cost.
Further, maximum components are German or American based hence distributor network was difficult to search and select.
Supply chain establishment taught us many things as a growing start up firm.
The experience was beneficial because with new challenges coming each day in initial time made us to explore better sourcing network.
Hence, today EVI has a very small but efficient supply chain network and lead times drastically reduced to less than a week for majority of components enabling faster product development and market capture.
A.T.
Kearney reports an astonishing figure of 1.5 million registered electric 3 wheelers till Juneᾲ017 without any government support and policy intervention.
This kind of steady growth of 9% every year sincerely highlights the positive and accelerated growth of EV in India.
Our hon’ble PM has already rolled out FAME II (Faster Adoption and manufacturing of electric and hybrid vehicles) is indicative of government’s keen interest on supporting EV on Indian roads.
Many state governments have already rolled their EV policies with Delhi being the first, pushing a positive growth in EV.
Further for EV charging franchise, government has already waived of any licensing requirement and subsidised the electricity tariff.
In my opinion the growth will accelerate as government is also keen on building charging infrastructure to backbone EV’s on road and subsiding & exempting taxes for EV drivers.
Well, any vehicle with a battery and motor can be my favourite EV as its silent and greener mode to travel.
I don’t have any personnel favourite but would love to drive every EV on Indian road
tutorial/image-manipulation-in-python-opencv-part2
Image Manipulations in OpenCV (Part-2)
This application will use many of Image processing functions which we have learned so far or will learn in this tutorial, so this will be a good practical example to cover all the functions.
etc.
Here we will learn to apply the following function on an image using Python OpenCV:
Bitwise Operations and Masking
Convolution & Blurring
Sharpening - Reversing the image blurs
Thresholding (Binarization)
Dilation, Erosion, Opening/Closing
Edge detection and Image gradients
Perspective & Affine Transform
Live Sketch Application
1. Bitwise Operations and Masking
Bitwise operations help you in image masking and helps you to create some simple images.
import cv2
import numpy as np
#we use only two dimensions because this is a grayscale image, if we were using a
#colored image, we had then used a rectangle=np.zeros((300,300,3),np.uint8)
#Making a square
square =np.zeros((300,300),np.uint8)
cv2.rectangle(square,(50,50),(250,250),255,-1)
cv2.imshow("square",square)
cv2.waitKey(0)
ellipse=np.zeros((300,300),np.uint8)
cv2.ellipse(ellipse,(150,150),(150,150),30,0,180,255,-1)
cv2.imshow("ellipse",ellipse)
cv2.waitKey(0)
BitwiseAND=cv2.bitwise_and(square,ellipse)
cv2.imshow("AND",BitwiseAND)
cv2.waitKey(0)
BitwiseOR=cv2.bitwise_or(square,ellipse)
cv2.imshow("OR",BitwiseOR)
cv2.waitKey(0)
#XOR_shows only where either exists by itself
BitwiseXOR=cv2.bitwise_xor(square,ellipse)
cv2.imshow("XOR",BitwiseXOR)
cv2.waitKey(0)
BitwiseNOT_elp=cv2.bitwise_not(ellipse)
cv2.imshow("NOT_ellipse",BitwiseNOT_elp)
cv2.waitKey(0)
cv2.destroyAllWindows()
2. Convolution & Blurring
is an mathematical operation performed on two functions producing a third function which is typically a modified version of original function.
we use kernel’s to specify the size over which we run our manipulating function over our image.
is an operation where we average the pixels within a region(Kernel)
OpenCV blurs an image by applying kernels, a kernel tells you how to change the value of any given pixel by combining it with different amount of neighboring pixels the kernel is applied to every pixel in the image one by one to produce the final image.
We can simply understand it by the following example.
The above is a 3X3 Kernel.
We multiply by 1/25 to normalize i.e.
sum to 1 we had been increasing the intensity or decreasing the intensity as in the case of brightening or darkening of images.
, given by the function cv2.filter2D (image, -1, kernel)
import cv2
import numpy as np
image = cv2.imread('elephant.jpg')
cv2.imshow('original',image)
cv2.waitKey(0)
kernel_3x3=np.ones((3,3),np.float32)/9
blurred=cv2.filter2D(image,-1,kernel_3x3)
cv2.imshow('3x3_blurring', blurred)
cv2.waitKey(0)
kernel_7x7=np.ones((7,7),np.float32)/49
blurred=cv2.filter2D(image,-1,kernel_7x7)
cv2.imshow('7x7_blurring', blurred)
cv2.waitKey(0)
cv2.destroyAllWindows()
too:
Averages value over a specified window.
Similar but uses a Gaussian window (more emphasis on points around the center).
Uses median of all elements in the window.
Blurs while keeping the edges sharp, it preserves the edges and line details.
We will see one by one below, first display the original image using below code:
import cv2
import numpy as np
image = cv2.imread('elephant.jpg')
cv2.imshow('original', image)
cv2.waitKey(0)
#cv2.blur
blur=cv2.blur(image,(3,3))
cv2.imshow('Averaging', blur)
cv2.waitKey(0)
#cv2.GaussianBlur
#instead of box filter, let’s try Gaussian kernel
Gaussian=cv2.GaussianBlur(image,(7,7),0)
cv2.imshow('Gaussian blurring',Gaussian)
cv2.waitKey(0)
It takes median of all pixels under the kernel area and central element is replaced with this median value.
#cv2.medianBlur
#takes median of all pixels under the kernel area and central element
#is replaced with this median value.
median=cv2.medianBlur(image,5)
cv2.imshow('median blurring',median)
cv2.waitKey(0)
Bilateral is very effective in noise removal while keeping the edges sharp
#cv2.bilateralFilter
#Bilateral is very effective in noise removal while keeping the edges sharp
bilateral=cv2.bilateralFilter(image,9,75,75)
cv2.imshow('bilateral blurring',bilateral)
cv2.waitKey(0)
cv2.destroyAllWindows()
import cv2
import numpy as np
image=cv2.imread('elephant.jpg')
cv2.imshow('original',image)
cv2.waitKey(0)
#parameter after None is the filter strength 'h'(5-10 is a good range)
#next is h for color components, set as same value as h again
dst=cv2.fastNlMeansDenoisingColored(image,None,6,6,7,21)
cv2.imshow('Fast means denois',dst)
cv2.waitKey(0)
cv2.destroyAllWindows()
ᾠfor single gray scale image
ᾠSingle color image
ᾠfor image sequence grayscale
ᾠfor image sequence colored
3. Sharpening - Reversing the image blurs
, it strengths or emphasizes on edges in the image.
Kernel = [-1,-1,-1],
[-1, 9,-1],
[-1,-1,-1]
Our kernel matrix sums up to one, so there is no need to normalize (i.e.
multiply by a factor to same brightness as of original), if kernel is not normalized to 1 the image would be brighter or darker.
import cv2
import numpy as np
image=cv2.imread('elephant.jpg')
cv2.imshow('original',image)
cv2.waitKey(0)
kernel_sharpening=np.array([[-1,-1,-1],
[-1, 9,-1],
[-1,-1,-1]])
#applying sharpening kernel to input image
sharpened=cv2.filter2D(image,-1,kernel_sharpening)
cv2.imshow('sharpened image',sharpened)
cv2.waitKey(0)
cv2.destroyAllWindows()
4. Threshoding (Binarization)
In opencv there is separate function for thresholding defined as
Cv2.threshold(image, threshold value, Max value, threshold type)
There are following threshold types:
cv2.THRESH_BINARY ᾠmost common
cv2.
THRESH_BINARY_INV ᾠmost common
cv2.THRESH_TRUNC
cv2.THRESH_TOZERO
cv2.
THRESH_TOZERO_INV
import cv2
import numpy as np
#load image as grayscale
image=cv2.imread('gradient.jpg',0)
cv2.imshow('original',image)
cv2.waitKey(0)
_,thresh1=cv2.threshold(image,127,255,cv2.THRESH_BINARY)
cv2.imshow('1 threshold',thresh1)
cv2.waitKey(0)
_,thresh2=cv2.threshold(image,127,255,cv2.THRESH_BINARY_INV)
cv2.imshow('2 threshold',thresh2)
cv2.waitKey(0)
_,thresh3=cv2.threshold(image,127,255,cv2.THRESH_TRUNC)
cv2.imshow('3 thresh trunc', thresh3)
cv2.waitKey(0)
_,thresh4=cv2.threshold(image,127,255,cv2.THRESH_TOZERO)
cv2.imshow('4 threshold', thresh4)
cv2.waitKey(0)
_,thresh5=cv2.threshold(image,127,255,cv2.THRESH_TOZERO_INV)
cv2.imshow('5 threshold', thresh5)
cv2.waitKey(0)
cv2.destroyAllWindows()
5. Dilation, Erosion, Opening/Closing
These are the operations in the field of mathematical morphology
ᾠit adds pixels to the boundaries of object in an image.
ᾠRemoves pixels at the boundaries of object in an image.
ᾠErosion followed by dilation.
ᾠDilation followed by erosion.
Opening is very much helpful in denoising the images as it first thins the image by erosion (removes the noise) and then dilates it.
There is sometimes confusion between dilation and erosion usually in pictures with white background, as opencv considers white background as image to be dilated or eroded instead of original picture, so in this case erosion works as dilation and vice-versa, as shown in image sample shown below.
removes pixels at the boundaries of objects in an image
import cv2
import numpy as np
image =cv2.imread('imagecv.png',0)
cv2.imshow('original',image)
cv2.waitKey(0)
#let's define our kernel size
kernel=np.ones((5,5),np.uint8)
erosion=cv2.erode(image,kernel,iterations=1)
cv2.imshow('Erosion’, erosion)
cv2.waitKey(0)
dilation=cv2.dilate(image,kernel,iterations=1)
cv2.imshow('dilation',dilation)
cv2.waitKey(0)
opening = cv2.morphologyEx(image,cv2.MORPH_OPEN,kernel)
cv2.imshow('opening',opening)
cv2.waitKey(0)
closing=cv2.morphologyEx(image,cv2.MORPH_CLOSE,kernel)
cv2.imshow('closing',closing)
cv2.waitKey(0)
cv2.destroyAllWindows()
6. Edge detection and Image gradients
Edge detection is very important area in computer vision, especially when dealing with contours.
Edges can be defined as boundaries of image, actually they are edges which define object in images they preserve a lot of information about the image.
can be defined as sudden changes (discontinuities) in an image and they can encode as much information as pixels.
The above image shows how computer vision identifies and recognizes the image.
There are three main types of edge detection algorithms
Sobel ᾠto emphasis on vertical or horizontal images.
Laplacian ᾠoptimal due to low error rate, well defined edges and accurate detection.
Canny Edge detection algorithm (devolped by john.F.Canny in 1986)
import cv2
import numpy as np
image =cv2.imread('input.jpg',0)
height,width=image.shape[:2]
sobel_x=cv2.Sobel(image,cv2.CV_64F,0,1,ksize=5)
sobel_y=cv2.Sobel(image,cv2.CV_64F,1,0,ksize=5)
cv2.imshow('original',image)
cv2.waitKey(0)
cv2.imshow('sobelx',sobel_x)
cv2.waitKey(0)
cv2.imshow('sobely',sobel_y)
cv2.waitKey(0)
sobel_OR=cv2.bitwise_or(sobel_x,sobel_y)
cv2.imshow('sobelOR',sobel_OR)
cv2.waitKey(0)
laplacian=cv2.Laplacian(image,cv2.CV_64F)
cv2.imshow('Laplacian',laplacian)
cv2.waitKey(0)
#in canny we need to provide two values: threshold1 and threshold2.
#any gradient larger than threshold 2 is considered to be an edge.
#any gradient larger than threshold 1 is considered not to be an edge.
#values in between threshold 1 and threshold 2 are either as edge or non-edge
#on how their intensities are connected, in this case any value below 60 are considered
#non edges wheareas any value above 120 are considered as edges.
canny=cv2.Canny(image,60,120)
cv2.imshow('canny',canny)
cv2.waitKey(0)
cv2.destroyAllWindows()
14.
Perspective & Affine Transform
, the original image shown below is clearly an non affine image as the edges are going to meet at some point however, we can straighten it by warping and taking the perspective transform.
function to generate the final output.
import cv2
import numpy as np
import matplotlib.pyplot as plt
image=cv2.imread('paper.jpg')
cv2.imshow('original',image)
cv2.waitKey(0)
points_A=np.float32([[320,15],[700,215],[85,610],[530,780]])
#we use a ratio of an A4 paper 1:1.41
points_B=np.float32([[0,0],[420,0],[0,592],[420,592]])
M=cv2.getPerspectiveTransform(points_A,points_B)
warped=cv2.warpPerspective(image,M,(420,594))
cv2.imshow('warpprespective',warped)
cv2.waitKey(0)
cv2.destroyAllWindows()
from the shape function instead of manually entering it.
import cv2
import numpy as np
import matplotlib.pyplot as plt
image=cv2.imread('box.jpg')
rows, cols=image.shape[:2]
cv2.imshow('original',image)
cv2.waitKey(0)
points_A=np.float32([[320,15],[700,215],[85,610]])
#we use a ratio of an A4 paper 1:1.41
points_B=np.float32([[0,0],[420,0],[0,592]])
#transformation matrix,M
M=cv2.getAffineTransform(points_A,points_B)
warped=cv2.warpAffine(image,M,(cols,rows))
cv2.imshow('warpaffine',warped)
cv2.waitKey(0)
cv2.destroyAllWindows()
8. Live Sketch Application
we are going to learn some new concepts of loops and functions.
If you are familiar with programming, you must have a broader idea of what the function and loops are.
However, in python the basic concept of loops and functions remains the same but the method to define them changes a little.
ᾠthis is a formal definition of a function a group of statements working together for a certain output.
is a function, in python function is defined by “defᾠand ends with a Ὰᾠmark.
Also the statements which are required to be inside the function or you can say which are required for the function to work properly, are side aligned automatically by the function.
So to come out of the functions the statements needed to be totally left aligned.
For the further references you can refer to google on how the functions are defined in python.
, here the binary inverse could also be done by bitwise_NOT but we had deliberately chosen this threshold binary inverse as it gives freedom to sets its parameters till we get a clear image.
While the ret is the Boolean telling that function is run successfully or not and the mask is the final output of the function i.e.
the processed image.
as it continuously had to capture the images, to give it a sense of a live video, where the frame rate of the video would be the frame rate of your webcam which is mostly between 24 to 60 fps.
, where the ret is the Boolean indicating that the function was successfully run or not and the frame contains the image taken by webcam.
import cv2
import numpy as np
#sketch generating function
def sketch(image):
#convert image to grayscale
img_gray=cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)
#cleaning up the image using Gaussian blur
img_gray_blur=cv2.GaussianBlur(img_gray,(5,5),0)
#extract edges
canny_edges=cv2.Canny(img_gray_blur,10,70)
#do an invert binarize the image
ret, mask=cv2.threshold(canny_edges,70,255,cv2.THRESH_BINARY_INV)
return mask
#initialize webcam, cap is the object provided by video capture
#it contains a Boolean indicating if it was successful(ret)
#it also contains the images collected from the webcam(frame)
cap=cv2.VideoCapture(0)
while True:
ret,frame=cap.read()
cv2.imshow('livesketcher',sketch(frame))
if cv2.waitKey(1) == 13: #13 is the enterkey
break
#release camera and close window, remember to release the webcam with the help of cap.release()
cap.release()
cv2.destroyAllWindows()
and you will be able to make something cool with Computer Vision.
tutorial/what-is-vfd-drive-circuit-types-working-advantage-disadvantages
What is VFD Drive Circuit: Its Operation, Types and Applications
There are lots of factories and plants in the world which use a different type of high power motors.
Due to the high power consumption, the factories and plants end up paying a high amount of energy bills.
To overcome the high power consumption and to increase the efficiency, VFD was introduced four decades ago but the circuitry was not strong enough.
or adjustable frequency drive.
The frequency determines the motor RPM and by controlling the AC frequency the motor RPM can be controlled.
Different types of VFDs are available in the electronics and electrical market ranging from small motor related applications to the high power induction motors.
Other than the three-phase VFDs, single phase VFDs are also available.
VFD Circuit and Its Operation
A VFD circuit consists of three parts.
Rectifier Section of VFD Circuit
rectifier section uses 6 diodes.
The diodes D1, D2, and D3 are connected with the positive rail and the diode D4, D5 and D6 are connected with the negative rail.
Those 6 diodes act as a diode bridge which converts the three-phase AC signal into a single DC rail.
The three-phase R, B, and Y are connected across the diode.
Depending on the sinusoidal wave polarity the diodes gets forward biased or reverse biased thus providing a positive pulse or a negative pulse in both positive and negative rail.
, just follow the link.
Filter Section of VFD Circuit
As we know the standard rectifier diodes only convert the AC signal to DC, but the output DC signal is not smooth enough because there are frequency dependent AC ripples are also associated with it.
To rectify the AC ripple and to make a smooth DC output there is a requirement of some sort of ripple rejection filters.
The standard component for the filter is to use different type of large capacitors and inductors.
In filter section, mainly the capacitor filters out the AC ripple and provides smooth DC output.
In some cases, other types of filters are also used to reduce the input AC noises and harmonics.
Switching or Inverter section of VFD Circuit
The switches are rapidly turned on or off and the load receives a pulsating voltage that is very similar to AC.
The output frequency is proportional to the switching rate.
High switching rate provides high-frequency output whereas low switching rate provides a low-frequency output.
Different types of VFD
Depending on how VFD converts AC power to DC power and make the rectification there are other types of VFDs are available in the market.
VSI type VFDs
This is the most common type of variable frequency driver.
In this type of VFDs, a simple diode bridge is used to convert the AC signal into DC and a capacitor is used to store the energy.
An inverter switching circuit uses the stored energy in the capacitor and provides the output.
1.It has a good speed range.
2.Multiple motor control facility.
Multiple motors can be connected with the single VSI type VFD.
3.Simple design.
4.It is cost effective from the production and installation side.
effect, the load motor face jerking during start and stop situation.
2.The output provides different types of harmonics and noises.
3.If the motor speed is controlled or the speed is decreased, the overall power factor is largely get hampered which results in poor power factor.
CSI type VFDs
, SCR bridge converter is used.
The output energy is filtered using series inductors as an alternative of capacitors for smooth current output.
CSI type VFDs act same as like constant current generator.
Instead of a square wave of voltage, CSI type VFDs is capable to provide square wave of current.
1.Reliable then VSI type VFDs.
2.Support higher horsepower induction motors where VSI is not a suitable choice.
3.Simple design.
4.Good regeneration capabilities.
1.The overall power factor is poor, especially at low RPM.
2.Cogging effect exists and could vibrate the motor shaft while running.
3.It is not suitable for multi-motor operation in respect of VSI.
PWM type VFDs
Using the PWM technique the VFDs are capable to provide stable voltage output maintained with a frequency ratio.
The construction uses a diode bridge to rectify the AC signal into a DC signal.
The switching circuit controls the duty cycle in a variable frequency range.
An additional regulator is used to regulate the PWM output to provide stable and proper voltage and current to the Load.
1.No clogging or jerking effect.
2.Wide speed and control range.
3.Consist different type of protection circuits.
4.Constant power factor.
5.Induce very high efficiency.
6.Energy efficient.
1.Complex to design.
2.Complex in respect of the implementation.
3.Requires additional hardware.
4.Audible noise generation in the driver circuit.
5.Costly solution.
How to select VFD for my Application?
To select the proper VFDs for a specific application, a good understanding of the load is required.
Different types of motors produce different types of torque.
In some applications constant torque is necessary whereas in other applications the torque needs to be controlled.
Also the load across the motor is determining factor of the motor specification, mainly the Power rating.
To select the appropriate VFD for the proper application we need to evaluate or consider the following things.
1. Horsepower of the motor
2. The cost
3. The operating environment of the VFD and motors
4. Single phase or three phase
5. Single VFD with single motor or single VFD with multiple motors
6. Additional control features requirements
Advantages of VFD
VFD offer high efficiency in terms of energy consumption other than any controller devices in the same segment.
Due to this, in case of large factories and plants where larger horsepower motors are required, VFD offers low power consumption thus lowering the energy bill amount and provides cost-saving opportunities.
during the motor start and stops condition, which also decrease the inrush load in the supply line, as well as provide a safety margin for the costly motors.
No additional costly electrical connection and control operations are needed.
There are options to connect multiple motors that can be controlled using single VFD which in further reduce additional system setup cost.
Disadvantages of VFD
However, despite the above advantages, there are a few disadvantages also associated with the VFD system.
The primary drawback of the VFD system is the initial setup investment.
For a factory or a plant where multiple high horsepower motors need to be controlled using VFDs, requires high investments.
The construction needs special types of Motor insulations, as well as the motors need to be specified for inverter rated applications.
Other major disadvantage of VFD is that the main source power line is highly disturbed with distortion, line notching harmonics.
Due to this, the other devices connected in the same power line also get hampered during the operating condition.
However, the advancement of the modern semiconductor industry has highly improved the construction of modern VFD systems.
Before the solid state device era, rotary machines are the main component used to make the VFDs.
In the modern microprocessor era, VFDs are equipped with all sorts of protections such as undervoltage, overvoltage, thermal overload protection etc.
with proper control facilities.
The Motor application in the industry is responsible for the 25% of the world’s electrical energy consumption, which can be efficiently controlled using VFDs.
tutorial/what-is-jfet-basics-construction-working-and-biasing
What is JFET: Its Construction, Working and Biasing Techniques
We can use JFET as voltage controlled resistors or as a switch, or even make an amplifier using the JFET.
It is also an energy efficient version to replace the BJTs.
JFET provides low power consumption and fairly low power dissipations, thus improving the overall efficiency of the circuit.
It also provides very high input impedance which is a major advantage over a BJTs.
We already discussed about MOSFET in previous tutorial, here will learn about JFET.
Types of JFET
Same like MOSFET it has two subtypes- N Channel JFET and P Channel JFET.
ᾮ
The current flowing through the Drain and Source is dependable on the voltage applied to the Gate terminal.
For the N channel JFET, the Gate voltage is negative and for the P channel JFET the Gate voltage is positive.
Construction of JFET
In the above image, we can see the basic construction of a JFET.
The N-Channel JFET consists of P-type material in N-type substrate whereas N-type materials are used in the p-type substrate to form a P channel JFET.
JFET is constructed using the long channel of semiconductor material.
Depending on the construction process, if the JFET contains a great number of positive charge carriers (refers as holes) is a P-type JFET, and if it has a large number of negative charge carriers (refers as electrons) is called N-type JFET.
In the long channel of semiconductor material, Ohmic contacts at each end are created to form the Source and Drain connections.
A P-N junction is formed in one or both side of the channel.
Working of JFET
One best example to understand the working of a JFET is to imagine the garden hose pipe.
Suppose a garden hose is providing a water flow through it.
If we squeeze the hose the water flow will be less and at a certain point if we squeeze it completely there will be zero water flow.
JFET works exactly in that way.
If we interchange the hose with a JFET and the water flow with a current and then construct the current-carrying channel, we could control the current flow.
When there is no voltage across gate and source, the channel becomes a smooth path which is wide open for electrons to flow.
But the reverse thing happens when a voltage is applied between gate and source in reverse polarity, that makes the P-N junction reversed biased and makes the channel narrower by increasing the depletion layer and could put the JFET in cut-off or pinch off region.
.
, whereas MOSFETs have depletion mode and enhancement mode.
JFET Characteristics Curve
, we can plot the I-V curve of a JFET.
where the current flow is uncontrolled.
increase.
Biasing of JFET
Different types of techniques are used to bias the JFET in a proper manner.
From various techniques, below three are widely used:
Fixed DC Biasing Technique
Self-Biasing Technique
Potential Divider Biasing
to bias the voltage.
In this technique, the gate current is zero again.
The source voltage is determined by the same ohms law V = I x R.
Therefore source voltage = Drain current x source resistor.
Now, the gate to source voltage can be determined by the differences between gate voltage and source voltage.
= 0 ᾠGate current x Source resistance.
Thus there is no external biasing source is needed.
The biasing is created by self, using the voltage drop across source resistor.
remain negative.
tutorial/what-is-inrush-current-and-how-to-limit-it
What is Inrush Current and How to Limit it?
Why Inrush Current Appears?
There are number of factors behind the cause of the inrush current.
Like some devices or systems which consists decoupling capacitor or smooth capacitor, draws a large amount of current at start to charge them.
Below given diagram will give you an idea about the difference between an inrush, peak and steady state current of a circuit:
It’s the maximum value of current attained by a waveform either in positive or negative region.
It is defined as the current at each time interval remain constant in a circuit.
A steady state current is achieved when di/dt = 0, which means the current remain unchanged with respect to time.
Occur instantaneously when device is turned on
Appears for a short time of span
Higher than the rated value of the circuit or device
Incandescent Lamp
Induction Motor Starting
Transformer
Turning ON SMPS based power supplies
Inrush Current in Transformer
is defined as the maximum instantaneous current drawn by the transformer when the secondary side is unloaded or in open circuit condition.
This inrush current harms the magnetic property of the core and cause an unwanted switching of transformer’s circuit breaker.
The magnitude of the inrush current is depends upon the point of AC wave at which the transformer is starting.
If transformer (at no load) turns on when the AC voltage is at its peak then no inrush current will occur at the starting, and if transformer (at no load) turns on when the AC voltage is passing through zero then the value of inrush current will be very high and it also exceeds the saturation current, as you can see in the below image:
Inrush Current in Motors
Like transformer induction motor do not have continuous magnetic path.
Reluctance of the induction motor is high due to the air gap between the rotor and the stator.
Therefore, due to this high reluctance induction motor requires high magnetizing current to produce the rotating magnetic field at starting.
The diagram below shows the full voltage starting characteristics of the motor.
(mainly called as soft starters) are used.
Should we care about Inrush Current and How to limit it?
, every time it turns ON.
Adjust the breaker tolerance may help us, but the components should withstand the peak value at in-rush.
while designing an electronic circuit or PCB.
Choosing the type of protection depends upon the frequency of the inrush current, performance, cost, and reliability.
works as an electrical resistor whose resistance is very high at low-temperature value.
The NTC thermistor connects in the series with the power supply input line.
It exhibits high value of resistance at ambient temperature.
So, when we turn on the device the high resistance limits the inrush current to flow into the system.
As the current flow continuously the temperature of the thermistor rises which reduces the resistance significantly.
Hence, the thermistor stabilizes the inrush current and allows the steady current to flow into the circuit.
The NTC thermistor is widely used for the current limiting purpose due to its simple design and low cost.
It also have some drawbacks like you cannot rely on thermistor in the extreme weather conditions.
are costlier and also increase the size of the system or circuit.
It consists of sensitive components that switch high incoming current.
Some of the active devices are Soft Starters, voltage regulators, and DC/DC converters.
These protections are used to protect the electrical as well as a mechanical system by limiting the instantaneous inrush current.
The below-mentioned graph show the inrush current value with the protection circuit and without the protection circuit.
We can clearly see how effective an inrush current protection is.
How to measure Inrush Current?
You all have seen the bicycle cart, to get it moving the rider needs to apply a vigorous force.
And, once the wheel starts moving the required force get reduced.
So, this initial force is equivalent to the inrush current.
Similarly, in motors, once the rotor starts moving the motor starts reaching the steady state where it does not require high current to run.
Like you can use Fluke 376 FC True-RMS Clamp meter to measure the inrush current.
Sometimes the inrush current shows a value which is higher than the rating of the circuit breaker, but still, the breaker does not trip.
The reason behind this is, the circuit breaker works on a time v/s current curve, like you are using a 10 amps circuit breaker, so the inrush current which is more than 10 amps should flow through the circuit breaker more than the rated time of it.
Follow the below mentioned steps to measure the inrush current:
Tested device should be turned off initially
Rotate the dial and set to the Hz- sign
Place the live wire into the jaw or use probe connected with the clamp meter
Press the inrush current button in the clamp meter, as shown in the above image
Turn the device ON, you will get the inrush current value on the meter’s display
tutorial/what-is-mosfet-basics-types-working-and-amplifier-design
What is MOSFET: Its Construction, Types and Working
or BJT has base, emitter, and collector, whereas a MOSFET has gate, drain and source connection.
Other than the pin configuration, BJT needs current for operation and MOSFET needs voltage.
MOSFET provides very high input impedance and it is very easy to bias.
So, for a linear small amplifier, MOSFET is an excellent choice.
The linear amplification occurs when we bias the MOSFET in the saturation region which is a centrally fixed Q point.
.
Types of MOSFETs
available.
These two types further have two subtypes
Depletion type MOSFET or MOSFET with Depletion mode
N-Channel MOSFET or NMOS
P-Channel MOSFET or PMOS
Enhancement type MOSFET or the MOSFET with Enhancement mode
N-Channel MOSFET or NMOS
P-Channel MOSFET or PMOS
Depletion type of MOSFET is normally ON at zero Gate to Source voltage.
If the MOSFET is N-Channel Depletion-type MOSFET then there will be some thresholds voltage, which is needed to make the device turn off.
For example, an N-Channel Depletion MOSFET with a threshold voltage of -3V or -5V, the gate of the MOSFET needs to be pulled negative -3V or -5V to turn off the device.
This threshold voltage will be Negative for the N channel, and positive in case of P channel.
This type of MOSFET is generally used in logic circuits.
In Enhancement type of MOSFETs, the device remains OFF at zero Gate voltage.
To turn on the MOSFET , we must provide a minimum Gate to Source voltage (Vgs Threshold voltage).
But, the drain current is highly dependable on this gate-to-source voltage, if the Vgs is increased, the drain current also increases in the same manner.
Enhancement type MOSFETs are ideal for constructing an Amplifier circuit.
Also, similarly like depletion MOSFET, it also has the NMOS and PMOS subtypes.
Characteristics and Curves of MOSFET
By providing the stable voltage across drain to source, we can understand the I-V curve of a MOSFET.
As stated above, the drain current is highly dependable on the Vgs, gate to source voltage.
If we vary the Vgs the Drain current will also vary.
Let's see the I-V curve of a MOSFET.
, the drain current is 0 when the Vgs voltage is below the threshold voltage, during this time the MOSFET is in the cut-off mode.
After that when gate-to-source voltage start increasing, the drain current also increases.
,
The curve showing that when the Vgs is 4.5V, the maximum drain current of IRF530 is 1A at 25 degree C.
But when we increase the Vgs to 5V, the Drain current is almost 2A, and finally at 6V Vgs, it can provide 10A of Drain Current.
DC Biasing of MOSFET and Common-Source Amplification
It is not a tough job if we determine how to bias the MOSFET and use it in a perfect operation region.
it provides perfect Q-point.
If we provide a small signal (time-varying) and apply the DC bias at gate or input, then under the right situation the MOSFET provides linear amplification.
/ dVgs.
It is an important parameter for the amplification factor.
At this point the drain current amplitude is
Id = gm x Vgs
can control the drain current as well as the drain voltage using the equation
Vds = Vdd - Id x Rd (as V = I x R)
x Vgs x Rd
Now by the equations, the gain will be
Amplified Voltage Gain = -gm x Rd
So, the overall gain of the MOSFET Amplifier is highly dependable on the transconductance and the Drain resistor.
Basic Common Source Amplifier Construction with single MOSFET
, the important thing is to achieve DC biasing condition.
To serve the purpose, a generic voltage divider is constructed using two simple resistors: R1 and R2.
Two more resistors are also required as Drain resistor and Source resistor.
To determine the value we need step by step calculation.
A MOSFET is provided with high input impedance, thus in operating condition, there is no current flow present in the gate terminal.
then the voltages across those three resistors are equal to the VDD.
or Drain-to-source voltage.
Now as per the KVL,
VDD = ID x Rd + VDS + ID x Rs
VDD = ID (Rd + Rs) + VDS
(Rd + Rs) = VDD ᾠVDS / ID
We can further evaluate it as
Rd = (VDD – VDS / ID) - RS
Rs can caluculated as Rs = VS / ID
(R2 / R1 +R2)
Fortunately, maximum values can be available from the MOSFET datasheet.
Based on the specification we can build the circuit.
Two coupling capacitors are used to compensating the cut-off frequencies and to block the DC coming from the input or getting to the final output.
We can simply get the values by finding out the equivalent resistance of the DC bias divider and then selecting the desired cutoff frequency.
The formula will be
C = 1 / 2πf Requirement
as Push-pull configuration, follow the link for practical application.
tutorial/image-manipulation-in-python-opencv-part1
Image Manipulations in Python OpenCV (Part 1)
etc.
Here we will learn to apply the following function on an image using OpenCV:
Image Transformations ᾠAffine and Non-Affine Transformation
Image Translations ᾠMoving image up, down, left and right
Rotation of image ᾠSpinning the image
Scaling, Resizing, and Interpolation
Image Pyramids ᾠAnother way of resizing
Cropping ᾠCutting out the image region you want
Arithmetic operations for Brightening and Darkening of images
1. Image Transformations ᾠAffine and Non-Affine Transformation
are of three types scaling, rotation and translation, the important thing in affine transformations is that lines are parallel before and after image transformations.
or projective transformations doesn’t preserve parallelism, length or angle, it does however preserves the collinearity and incidence, collinearity means that the two points lie on the same straight line.
2. Image Translations ᾠMoving image up, down, left and right
Image translation is moving the image up, down, left and right and even diagonal if we implement x and y translation at the same time.
but for that we need a translation matrix.
,
T = 1 0 Tx
0 1 ty
are the directions in which the image shifts takes place.
is shift along X-axis (Horizontal)
is shift along Y-axis (Vertical)
# this is an affine transformation that simply shifts the position of an image
# we use cv2.warpAffine to implement these transformations.
import cv2
import numpy as np
image = cv2.imread('input.jpg')
# store the height and width of image
height,width = image.shape[:2]
print(image.shape[:2])
quater_height, quater_width = height/4, width/4
T = np.float32([[1,0,quater_width],[0,1,quater_height]])
img_translation=cv2.warpAffine(image,T,(width,height))
print(T)
cv2.imshow('original_image', image)
cv2.waitKey(0)
cv2.imshow('Translation',img_translation)
cv2.waitKey(0)
cv2.destroyAllWindows()
[ 0.
1. 45.75]]
3. Rotation of image ᾠSpinning the image
Rotation of the image is rotating an image about a point or the point in the center of the image, just as the rotating point acts like a pivot.
Rotation matrix, M matrix = Cosθ -Sinθ
Sinθ Cosθ
direction.
but instead of translation matrix as in previous case here we use the rotation matrix.
import cv2
import numpy as np
image=cv2.imread('input.jpg')
height, width=image.shape[:2]
#divide the height and width by 2 to rotate the image about it's center
rotation_matrix=cv2.getRotationMatrix2D((width/2, height/2),90,1)
rotated_image=cv2.warpAffine(image,rotation_matrix,(width,height))
cv2.imshow('original image',image)
cv2.waitKey(0)
cv2.imshow('rotated image', rotated_image)
cv2.waitKey(0)
cv2.destroyAllWindows()
Now the image is rotated by 90 degrees, it is cropped because of the canvas size, since the canvas size remains the same but due to rotation image size doesn’t fits into canvas size.
It could be adjusted by setting the scaling factor to negative, but it allows a black background behind the image.
it, but it would rotate the image by the multiples of 90 degrees in anti-clockwise direction.
4. Scaling, Resizing and Interpolation
Scaling and resizing are affine transformations, resizing the image is what we have done quite a time and we have also dealt with interpolation, like when you are resizing the image to larger size in which we are expanding the pixels, there are some gaps in the pixels and that’s where interpolation comes in.
It can occur on increasing the image size from smaller to larger or decreasing the image size from larger to smaller.
in OpenCV like
ᾠgood for shrinking or down sampling
- fastest
ᾠgood for zooming or up sampling (default)
- better
- best
# resizing is very easy using the cv2.resize function, its arguments are
#cv2.resize(image,dsize(output image size), x_scale, y_scale, interpolation)
import cv2
import numpy as np
image=cv2.imread('input.jpg')
cv2.imshow('Original_image',image)
cv2.waitKey(0)
#let's make the image 3/4 the the original image size i.e.
scales down to 75%
image_scaled=cv2.resize(image,None,fx=0.75,fy=0.75)
#since linear interpolation is default method for open cv we don’t need to implement it as a function.
cv2.imshow('scaling_linear interpolation', image_scaled)
cv2.waitKey(0)
#let's double the size of our image
img_double=cv2.resize(image,None,fx=2,fy=2,interpolation=cv2.INTER_CUBIC)
cv2.imshow('scaing_cubicInterpolation',img_double)
cv2.waitKey(0)
# let's do the resizing by exact dimensions
image_resize=cv2.resize(image,(200,300),interpolation=cv2.INTER_AREA)
cv2.imshow('scaling_exact',image_resize)
cv2.waitKey(0)
cv2.destroyAllWindows()
5. Image Pyramids ᾠAnother way of resizing
It’s simply a different way of resizing that allows us to easily and quickly scale images, scaling down reducing the height and width of the new image by half.
This comes useful when making object detectors that scales the images each time it looks for an object.
import cv2
image=cv2.imread('input.jpg')
smaller=cv2.pyrDown(image)
larger=cv2.pyrUp(smaller)
cv2.imshow('original',image)
cv2.waitKey(0)
cv2.imshow('smaller',smaller)
cv2.waitKey(0)
cv2.imshow('larger',larger)
cv2.waitKey(0)
cv2.destroyAllWindows()
In larger image you will notice that still being of the same size of the original image its little blurry because its being converted from smaller image to larger image directly.
But if we interpolate it the image quality becomes improved as of the previous one because interpolation estimates the pixels while filling in the spaces when image is enlarged.
Now running the same code but with cubic interpolation gives a better quality of large image.
Below images shows the comparison among original image, up scaled version of image, smaller image and cubic interpolated version of smaller image.
import cv2
image=cv2.imread('input.jpg')
smaller=cv2.pyrDown(image)
larger=cv2.pyrUp(smaller)
cv2.imshow('original',image)
cv2.waitKey(0)
cv2.imshow('smaller',smaller)
cv2.waitKey(0)
cv2.imshow('larger',larger)
cv2.waitKey(0)
# increasing the quality of converted larger image from smaller image using cubic interpolation
img_double=cv2.resize(smaller,None,fx=2,fy=2,interpolation=cv2.INTER_CUBIC)
cv2.imshow('scaing_cubicInterpolation',img_double)
cv2.waitKey(0)
cv2.destroyAllWindows()
function.
6. Cropping ᾠCutting out the image region you want
Cropping images refers to extracting a segment of image.
using the below code
Cropped=image [start_row: end_row, start_col: end_col]
We put the image array and using indexing tools or method in numpy, we define start row to end row and start column to end column separated by a comma that extracts the rectangle we want to crop to get the image.
import cv2
import numpy as np
image=cv2.imread('input.jpg')
height, width=image.shape[:2]
#let's get the starting pixel coordinates(top left of cropping rectangle)
start_row, start_col=int(height*.25),int(width*.25)
#let's get ending pixel coordinates(bottom right)
end_row, end_col=int(height*.75),int(width*.75)
#simply use indexing to crop out the rectangle we desire
cropped=image[start_row:end_row, start_col:end_col]
cv2.imshow("original image",image)
cv2.waitKey(0)
cv2.imshow("cropped image”, cropped)
cv2.waitKey(0)
cv2.destroyAllWindows()
, they are just given to get the easy identification for the user.
7. Arithmetic operations for Brightening and Darkening of images
Arithmetic operations in OpenCV basically are adding or subtracting matrixes to the image, adding or subtracting matrixes has effect on increasing or decreasing of brightness.
that gives matrixes of 1’s same size as of our image.
import cv2
import numpy as np
image=cv2.imread('input.jpg')
#create a matrix of one's, then multiply it by a scaler of 100'
#np.ones gives a matrix with same dimension as of our image with all the values being 100 in this case
M = np.ones(image.shape, dtype="uint8") * 100
#we use this to add this matrix M to our image
#notice the increase in brightness
added=cv2.add(image,M)
cv2.imshow("Added",added)
cv2.waitKey(0)
#likewise we can also substract
#notice the decrease in brightness
subtracted=cv2.subtract(image,M)
cv2.imshow("subtracted",subtracted)
cv2.waitKey(0)
cv2.destroyAllWindows()
This is how OpenCVcan be used to apply many different image processing operations on image.
We will continue with other image manipulation functions in next tutorial.
article/applications-of-iot-in-energy-industry
Applications of IoT in the Energy Industry: Generation, Transmission and Consumption
, one industry after the other.
This will involve use cases, current industry trends and future applications with the aim of providing useful insight to all seeking to deploy IoT based solutions.
We will look at how IoT is being used or can be used to transform the energy sector from energy generation to transmission, distribution, and consumption.
Transforming Energy Generation with IoT
The goal for power generation is to achieve affordability, availability, sustainability and reduce the use of fossils and emissions.
Many organizations like GE, across the world are increasingly leveraging on IoT to achieve these goals.
There are three main areas where IoT can be very Impactful in Power generation.
This is probably one of the most popular uses of IoT in industrial applications.
Connected sensors are being used to measure wear, tear, vibration, temperature, and other parameters to determine the overall health of assets from turbines to transmission lines.
Trends in the data obtained from sensors could be used to estimate the “time to failureᾠof key infrastructures and plan maintenance, reducing downtime due to unscheduled maintenance and help avoid the economic consequences of such downtimes.
Adopting IoT in power generations could also help identify safety issues like gas leakages before they cause harm to workers and equipment, generally helping stations attain new safety levels.
IoT has the ability to provide real-time information about the overall state of the entire generation station and this is greatly helping plant automation.
Real-time data is being used to fine-tune the operations of plants, increasing energy conversion from fuels and reducing the costs of maintenance.
A major goal for power generation is the eradication of fossil fuels but in the meantime, generating stations are able to cut down on emissions by combining energy generated through renewable means like Wind and Solar with the traditional coal or gas stations.
IoT provides generating station with information on peak periods which helps them plan alternation between renewable sources and fossils while also facilitating the storage of excess energy and its use during peak demand periods.
The output and uptime of renewable sources can also be easily maximized using IoT based solutions as it helps to ascertain the production values and overall health of renewable sources irrespective of their location.
IoT is rapidly leading to energy decentralization.
It is at the core of several new business models which are paving the way for commercialization of small and medium scale renewable energy solutions.
From “pay as you useᾠoff-grid solar system powering homes in developing countries like Nigeria, to large-scale, privately owned stations contributing energy to the grid in developed countries.
It is also providing utilities with the information required to create flexible tariffs (e.g higher tariffs during peak periods) giving consumers more options.
Transforming Energy Transmission and Distribution with IoT
The problems during transmission and distribution to some extent are similar.
They involve line failures, fault detection, losses on the lines among others.
Most of these problems could be solved with IoT.
Depending on the setup, assets involved with power transmission and distribution usually include substation equipment, transmission lines amongst others.
Each of these equipment develops faults and fail due to factors like overloading, vandalization etc.
With IoT, they can be monitored remotely with a range of sensors that monitor parameters like temperature, detect falling of utility poles before it causes safety hazards and detects security breaches to prevent vandalism which is rampant in developing countries.
The ability of the sensors to identify failures and their sources, before they become critical, increases the productivity of repair teams and reduces downtime and other related losses.
The overall spending on parts and repairs are reduced making electricity more available and affordable.
IoT has the ability to provide the real-time information needed to effectively manage congestion on T&D lines.
With IoT, the grid can ensure the connected generation stations have met the connection requirements from frequency to voltage control to prevent instability.
One of the biggest future trends in electricity generation is the contribution of regular homes to the energy grid.
Excess energy generated by solar panels at the rooftops in several homes are contributed/sold to the Grid.
One of the key technologies that will drive this transformation is the IoT.
The connection of renewable energy based generation plants with varying production levels to the grid will bring about variations in voltages at different nodes on the grid causing changes in power flow, but all of these can be, managed using real-time data provided by IoT solutions, auto-adjusting the grid to maintain stability.
Sensors installed at different substations and along distribution lines could provide real-time information on power consumption in different areas which could help the utilities make automated and smart decisions around voltage control, network configuration, load switching among others.
Trends in the data supplied could also be used as the basis for infrastructure upgrade and development.
Transforming Energy Consumption with IoT
Consumption is by far the section of the energy cycle where IoT has had the most impact.
It started with AMR based (semi) smart meters and thermostats and has evolved to Smart electricity meters that predicts consumption pattern and with your permission control the supply of power to certain power-hungry equipment during peak time when power is expensive.
Web-connected lightings that know when no one is home and automatically switches off the lights that were left on.
Some of the important opportunities IoT is enabling on the consumer side of energy are discussed below.
1. Smart Decision Making
IoT is helping consumers save cost and make smart decisions about their power usage.
Data from smart meters are sent to mobile app through which consumers can access how much power has been consumed, how much more they can afford to consume based on their budget and take steps to tune consumptions accordingly.
Consumers can turn off the supply of power to certain appliances and set conditions under which other appliances come on.
With this, they are able to eradicate waste and optimize their consumption.
2. Access to Dynamic Billing and flexible Tariffs
As mentioned above, IoT has created a plethora of business models that have increased the availability and affordability of energy and the biggest beneficiaries are the consumers who now have access to divers plans and tariffs to subscribe to for constant and affordable power supply.
3. New Power Solutions
Alongside new business models are new IoT based power solutions that facilitate monitoring, low scale generation, and storage of power for consumers.
We are gradually moving closer to a future where consumers can choose to buy power during periods when the tariffs are low and use during peak periods when tariffs are expected to be high.
4. Reduced Downtime
New line of smart meters, enabled for two-way communication between the distribution station and consumer, are being deployed in developed countries.
These meters send downtime notifications and other critical operation information to utility agencies.
Utility agencies can act on this data and respond more quickly to outages due to faults and other factors.
The meters also provide real-time data (Load forecasting) that helps the grid adjust power distribution as a result of variation in peak time across different areas.
5. Sale of Power to the Grid
IoT is enabling technologies that could help small homes sell excess energy generated from sources like solar panels and wind plants to the Grid.
With technologies like “Vehicle to Gridᾬ even Electric cars could start contributing excess, unused energy to the grid.
6. Zero Net Energy Buildings
IoT is also powering consumer driven concepts like the Zero Net Energy building.
Zero Net energy means all the energy needs of that house is generated by the house mostly via the use of renewable energy sources.
Each of the applications mentioned above represents opportunities for entrepreneurs and utilities to deliver additional value to customers and the combination of all these applications will certainly help make energy cleaner, cheaper, more available and sustainable.
tutorial/thyristor-commutation-technique
Thyristor Commutation Techniques
It can be done by bringing the Thyristor back into the forward blocking state from the forward conduction state.
To bring the Thyristor into forward blocking state, forward current is reduced below the holding current level.
For the purpose of power conditioning and power control a conducting Thyristor must be commutated properly.
in our previous Article.
There are mainly two techniques for Thyristor Commutation: Natural and Forced.
The Forced commutation technique is further divided into five categories which are Class A, B, C, D, and E.
Below is the Classification:
Natural Commutation
Forced Commutation
Class A: Self or Load Commutation
Class B: Resonant-Pulse Commutation
Class C: Complementary Commutation
Class D: Impulse Commutation
Class E: External Pulse Commutation
Natural Commutation
, and it is named so because it doesn’t require any external circuit.
When a positive cycle reaches to zero and the anode current is zero, immediately a reverse voltage (negative cycle) is applied across the Thyristor which causes the Thyristor to turn OFF.
A Natural Commutation occurs in AC Voltage Controllers, Cycloconverters, and Phase Controlled Rectifiers.
Forced Commutation
Mainly forced commutation is used in Chopper and Inverters circuits.
Forced commutation is divided into six categories, which are explained below:
1. Class A: Self or Load Commutation
Class A is also called as “Self-Commutationᾠand it is one of the most used technique among all Thyristor commutation technique.
In the below circuit, the inductor, capacitor and resistor form a second order under damp circuit.
When we start supplying the input voltage to the circuit the Thyristor will not turn ON, as it requires a gate pulse to turn ON.
Now when the Thyristor turns ON or forward biased, the current will flow through the inductor and charges the capacitor to its peak value or equal to the input voltage.
Now, as the capacitor gets fully charged, inductor polarity gets reversed and inductor starts opposing the flow of current.
Due to this, the output current starts to decrease and reach to zero.
At this moment the current is below the holding current of the Thyristor, so the Thyristor turns OFF.
2. Class B: Resonant-Pulse Commutation
Class B commutation is also called as Resonant-Pulse Commutation.
There is only a small change between Class B and Class A circuit.
In class B LC resonant circuit is connected in parallel while in Class A it’s in series.
Now, as we apply the input voltage, the capacitor starts charging upto the input voltage (Vs) and Thyristor remains reversed biased until the gate pulse is applied.
When we apply the gate pulse, the Thyristor turns ON and now the current start flowing from both the ways.
But, then the constant load current flows through the resistance and inductance connected in series, due to its large reactance.
Therefore, due to this opposing commutating current, when the anode current is getting lesser than the holding current, Thyristor turns OFF.
3. Class C: Complementary Commutation
Class C commutation is also called as Complementary Commutation.
As you can see the circuit below, there are two Thyristor in parallel, one is main and another is auxiliary.
Initially, both the Thyristor are in OFF condition and the voltage across capacitor is also zero.
Now, as the gate pulse is applied to the main Thyristor, the current will start flowing from two paths, one is from R1-T1 and second is R2-C-T1.
Hence, the capacitor also starts charging to the peak value equal to the input voltage with the polarity of plate B positive and plate A negative.
Now, as the gate pulse is applied to the Thyristor T2, it turns ON and a negative polarity of current appear across the Thyristor T1 which cause T1 to get turn OFF.
And, the capacitor starts charging with the reverse polarity.
Simply we can say that when T1 turns ON it turns OFF T2 and as T2 turns ON it turns OFF T1.
4. Class D: Impulse Commutation
Class D commutation is also called as Impulse Commutation or Voltage Commutation.
As Class C, Class D commutation circuit also consists of two Thyristor T1 and T2 and they are named as main and auxiliary respectively.
Here, diode, inductor, and auxiliary Thyristor form the commutation circuit.
Initially, both the Thyristor are in OFF state and voltage across capacitor C is also zero.
Now as we apply the input voltage and trigger the Thyristor T1 the load current starts flowing through it.
And, the capacitor starts charging with polarity of plate A negative and plate B positive.
Now, as we trigger the auxiliary Thyristor T2, the main Thyristor T1 turns OFF and the capacitor starts charging with the opposite polarity.
When it gets full-charged, it causes the auxiliary Thyristor T2 to turn OFF, because a capacitor does not allow the flow of current through it when it gets fully charged.
Therefore, the output current will also be zero because at this stage because of both the Thyristorsare in OFF state.
5. Class E: External Pulse Commutation
Class E commutation is also called External Pulse Commutation.
Now, you can see in the circuit diagram, the Thyristor is already in forward bias.
So, as we trigger the Thyristor, the current will appear at the load.
The capacitor in the circuit is used for the dv/dt protection of the Thyristor and the pulse transformer is used to turn OFF the Thyristor.
Thyristor will turn OFF.
is holding current.
tutorial/getting-started-with-opencv-image-processing
Now the output of the amplifier will be -
Vout = open loop gain x (Vin - Vout)
Or,
Vout = A(Vin - Vout
where di/dt is the rate of current change
L is the self-inductance.
The induced EMF direction will be opposite of the applied current source.
:
LC Meter using Arduino: Measuring Inductance and Frequency
How to measure value of Inductor or Capacitor using Oscilloscope ᾠResonant Frequency Method
However, this is a ridiculous number of calculations, even for a base window of 24 x 24 pixels (180,000 features generated).
and it found most informative features in the image.
Boosting is the process by which we use weak classifiers to build strong classifiers, simply by assigning heavier weighted penalties on incorrect classifications.
Reducing the 180,000 features to 6000, which is still quite a bit features.
- for face detection, the Viola Jones method used 38 stages.