Electric Vehicle Components, Electric Vehicle Tutorial
Hello guys, welcome back to our blog. In this article “Electric Vehicle Tutorial“, we are pointing out the key areas you need to learn about EV technology. EV Technology is one of the rapidly evolving areas with lots of research and innovations happening every day.
Also, if you wish to learn in detail with real-time knowledge, you may check out this online EV course you can pursue.
If you have any electrical, electronics, and computer science doubts, then ask questions. You can also catch me on Instagram – CS Electrical & Electronics.
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Electric Vehicle Tutorial
What makes Electric Vehicle Technology a great career choice?
Electric vehicles are revolutionizing the automobile world. These pollution-free, silent, and high-performance vehicles are expected to make the conventional IC engine vehicles obsolete in the near future, creating a huge demand for Electric Vehicle Engineers.
Understanding the Fundamentals of an Electric Vehicle Technology
Electric Vehicles vs Conventional Vehicles
Comparing the IC engine with the EV motor, we can find that
01. In IC engines, the linear motion of the piston has to be converted into rotational motion. This causes problems and wear-and-tear with usage, as there are lots of moving parts. Whereas in EV motors, we have direct rotational motion.
02. Unlike the internal combustion engine, an induction motor is self-started easily. No need for an ignition system.
03. As the power output of an IC engine is uneven, many accessories are required to overcome this problem. In the case of induction motor, on the other hand, we get a uniform power output.
As we see, many components in the IC engine can be avoided easily in an EV.
All these factors contribute to a higher power-to-weight ratio resulting in great vehicle performance.
A little about the working of an Electric Car
Let’s see how electric cars have achieved superior performance by analyzing the technology behind the induction motor, inverter, powertrain, lithium-ion battery, and regenerative braking system, in a logical step-by-step manner.
EV Motors – the Powerhouse of an Electric Car
The main highlight of an induction motor is that they run on different frequencies and the speed is proportionate to the frequency.
This allows them to function according to the electricity supply. All you need to do is increase or decrease the frequency, and as a result, we can control the drive wheel speed accordingly.
For a better understanding, you must learn in detail how an induction motor works. The motor speed ranges from 0 to around 18,000 RPM. This is a major advantage electric cars have over internal combustion cars.
One drawback of Internal Combustion engines is that they produce torque and power output within a limited speed range only.
Hence, it is not an efficient technique to directly connect the engine rotation to the drive wheel. This is where transmission plays a vital role in varying the drive wheel speed.
But induction motors work well & efficiently in any speed range. No speed varying transmission is required for an electric car.
Usage of Inverters in Electric Vehicle
The motor is powered by a battery pack. Now, the battery produces DC power and it has to be converted into AC before supplying to the motor. This is done with the help of an inverter. This power electronic device also controls the AC power frequency thus controlling the motor speed.
The inverter can also vary the amplitude of the AC power which can control the motor power output. Thus the inverter also acts as the control unit of the electric car.
EV Powertrain and Drivetrain
The drivetrain of an electric vehicle gives the power to move the wheels. The powertrain includes both the motor and the drivetrain system.
The power generated by the motor is transferred to the drive wheels with the help of a gearbox with a simple single-speed transmission as the motor is much more efficient.
Even achieving the reverse gear is quite easy in an electric car by just changing the order of the power phase. Here an electric car transmission is only needed for reducing speed and its associated torque multiplication.
In the tesla, this is accomplished using a state-of-the-art algorithm with help from sensors and controllers. Tesla has replaced a complex mechanical hardware system with smart, responsive software.
The Regenerative Braking System
It is even possible to drive an electric car efficiently using just one pedal with the help of a powerful regenerative braking system. With this, as soon as the accelerator pedal is released the regenerative braking comes into action.
Interestingly, during regenerative braking, the same induction motor acts as a generator. In this scenario, the wheels drive the rotor of the induction motor.
In an induction motor the speed of the rotor is comparatively less than the RMF speed, and to convert it into a generator, we just have to make sure the rotor speed is greater than the RMF speed.
In an EV, the inverter plays an important role in adjusting the input power frequency and keeping the RMF speed lower than the rotor speed. This generates electricity in the stator, which is much greater than the electricity supply. The generated electricity can then be converted and stored in the battery pack.
During the process, an opposing EM force acts on the rotor, which causes the drive wheels and the car to slow down. Though the brake pedal can be applied for a complete stop.
Battery Management System (BMS) in an EV
Lithium-ion batteries are popular for several applications including electric vehicles and energy storage systems. Because of their high power density, low safety charge, and relatively low cost.
However, individual battery cells alone cannot provide enough power to operate a whole energy storage system or support an electric power grid. So we combine many cells to create a module and then connect many modules to create the pack.
BMS or Battery Management System plays a very important role in electric vehicles. To monitor and maintain the battery pack for proper usage, a BMS is needed. The main functions of BMS are
- Cell balancing: equalizing the Soc and voltage of each cell
- Protecting the battery pack from overcurrent, overvoltage, & under-voltage condition
- Monitoring the temperature, & isolating the BMS if the temperature exceeds
- Monitoring current, voltage, SoC (state of charge), SoH (state of health)
- Efficient charging & discharging
These are the main functions of BMS.
EV Energy Storage System – The Battery Pack
The battery pack, which surprisingly is just a collection of common lithium-ion cells just like the ones used in your daily life! The cells are connected in a combination of series and parallel arrangements to produce the required power to run the electric car.
These cells are arranged as detachable modules with around 16 modules in a battery pack constituting nearly 7,000 cells. Two key elements make up an efficient battery management system: thermal management and charge balancing.
An Overview of the Thermal Management System in Electric Vehicles
Each lithium-ion battery has an acceptable operating temperature range. A cell operating outside of its safe temperature range causes performance degradation and irreversible damage.
In extreme cases, it can even cause thermal runaway, excessive overheating of the cell, and possible combustion. BMS uses sensors to measure the temperatures and controls the heat by distributing coolant where it is needed.
Glycol coolant is passed through metallic inner tubes through the gap between the cells, which is a major innovation from Tesla. To improve the effectiveness of cooling, many small cells are used instead of a few big cells. This also minimizes thermal hot spots and even temperature distribution is achieved which leads to a higher battery pack life.
The heated Glycol is cooled down by passing through a radiator at the front of the vehicle. Moreover, the battery pack is placed close to the ground level to lower the vehicle’s center of gravity, thus improving the stability of the car considerably. It also gives a good structural rigidity to electric cars.
Charge balancing in Electric Vehicles
Charge balancing is a matter of consideration due to the manufacturing inconsistencies. Even brand new cells of the same type have slight differences like capacity impedance and the self-discharge rate which causes the cells to age at different rates.
This results in significant energy imbalance within the cells in a module, hence the degradation of its performance. Passive balancing is a conventional way to address this issue by removing excess energy in the cells. The system drains all of the cells to the same point so that they recharge fully and at the same rate.
But passive charging is not helpful when the battery is being discharged as the capacity of a module is still limited by the weakest cell. Active balancing is a more energy-efficient way to balance and compared with passive balancing it redistributes the energy among cells rather than dissipate and waste it.
Power electronics devices are used to move energy from the strong cells to weak cells maximizing the available energy and increasing the effects of the capacity of the module.
Wireless Charging of EV
Another improvement in EV charging systems is with the wireless charging technology. Different organizations and companies have come up with technologies for charging electric vehicles while waiting at a parking slot or even while driving over a special track on the roads.
These technologies rely on using inductive magnetic fields for charging. Although charging in parking lots is quite easy to implement, charging while the vehicle is moving over a track is quite challenging, and requires a very high infrastructure facility.
Battery Swap technology
One of the major drawbacks of EVs is that it takes hours to charge the battery pack. If we fast charge the batteries, we are degrading the battery at a much faster rate than the usual slow charging.
This is where battery swapping comes into play. It is accomplished with the help of little robots which replace the depleted batteries with new fully charged ones. The whole process may take about 2 to 10 minutes.
Battery swapping has been adopted by many companies and yet is an area with a major scope of improvements & innovations. One of the issues with these battery swapping stations is that they are expensive. As the batteries are massive and it’s not easy to implement.
Some companies have come up with modular batteries so that the swapping stations can be smaller and comparatively less expensive. Another advantage of modular batteries is the ability to fit into different sizes. If it’s a big car, you can put in more and less in a small car.
Future of Electric Vehicles
Electric cars are much safer than conventional cars, and even the cost of maintaining and driving them is much lower than that of an IC engine car. With the drawbacks of electric cars evaded through the advent of improved technology, electric cars promise to be the cars of the future.
This was all about “Electric Vehicle Tutorial“. I hope this article “Electric Vehicle Tutorial” may help you all a lot. Thank you for reading.
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