Main Components of EV | Parts of Electric Vehicle

Evolution of Electric Vehicle

The global automobile population has started its transition to Electric Vehicles, with 54,577 units just being sold in the month of Feb in 2022.  The rising cost of petrol, the decreasing cost of components of an EV, and an increase in the adoption of EV by the general populace are among the reasons why we are currently amidst an EV renaissance. 

 
The electric powertrain has a few salient components that differentiate it from its ICE counterparts. These are,

 

• Battery pack
• Accumulator
• Precharge Circuit
• Precharge circuit 
• Insulation Monitoring Device
• Battery Management System 

  

 

To understand how the different parts of an electric powertrain interact with each other, you should first understand the flow of energy in an Electric Vehicle. Energy from the electric grid is stored in the battery pack, from where it goes to the pre-charge circuit, and from there to the motor, where the electric energy is converted into kinetic energy. 

 

 

 

Accumulator

Any component that stores energy is called an accumulator - this includes a fuel tank. Lithium-ion cells are the beating heart of any EV and the increased efficiency of which is the reason we are witnessing an increase in the number of EVs being sold in the world today. There are certain prerequisites that have to be met while designing a Lithium-ion battery pack. 

These packs operate between the temperature range of 45*C to 60*C and they have to be charged and discharged in a very specific way (as specified by the manufacturer), these batteries cannot be overcharged beyond their rated voltage levels as this will result in a thermal runoff.

A thermal runoff is an uncontrollable chain reaction in which the external heat creates chemical reactions within the battery that produces heat which in turn sets off a chemical reaction. A thermal runoff is one of the few drawbacks of an EV and has become a subject of public scrutiny in lieu of the Electric Vehicle fires around India. 

 

Battery Management System

One of the ways manufacturers control this volatile element of lithium-ion batteries is through a Battery Management System or the BMS. 

A BMS regulates and monitors every cell of the lithium-ion battery, it monitors the temperature of the pack and regulates the voltage of each individual cell. The Battery Management System also ensures that the temperature of the battery pack does not go beyond the defined temperature range.

 

 

When an EV system is turned on, the battery pack is first checked by the BMS, which then tells the AIR (accumulator isolation relay) to switch on the power by activating the main contactor, the main contractor carries 400amps but can be switched on by a 12V supply. 

 

Precharge Circuit

The motor is the component of the EV that powers the drive train, when 400V is applied across the system, there is no resistance between the battery and the motor. Without any resistance, this high current will fry the system. In order to reduce the damage, all EVs are designed and equipped with a precharge circuit. 

 

The precharge circuit is a resistor that connects the battery and the capacitor in the controller, which then safely powers the motor. Once the capacitor is charged and there is a steady voltage saturation within the circuit, the high current from the battery safely flows through the system. After ensuring that the current will not fry everything between the battery and the motor the precharge circuit changes to the non-resistive part. 

 

IMD  - Insulation Monitoring Device 

Why do we need insulation? 

One of the major reasons why EVs need to be insulated is that anything about 660volts of DC will kill a human if exposed for more than 30 seconds. Materials used to insulate wires in an EV include; acrylic, Teflon sheets, nylon fibers, and glass fiber sheets. 

If the vehicle gets into an accident and the insulation is scraped off, then IMD will be able to prevent the user from getting shocked and will secure the life of the user. The IMD achieves this by generating a sinusoidal wave that moves through the chassis every millisecond, if there is a persistent change in the waveform that it receives back, the IMD switches off the AIR and the EV will be shut down. 

  

Precharge circuit

Whenever there is an impact or hard braking, the entire system is cut off. To prevent the high voltage leak as mentioned before 60V is dead. When there is more than 9g of acceleration, it gets shut down automatically by connecting to a contactor and shutting off the power supply from the battery. 

 

 

Motor

A motor is the culmination of the energy conversion that starts from the battery, it is the central piece of the puzzle that propels the Electric Vehicle forward. The motor functions by employing the principles and fundamentals of magnetism, like-side attracts and the opposite reflects. When an electric current passes through a circuit, it creates a magnetic field that opposes the electric field of the rotator and pushes the rotator forward creating a rotating magnetic field in the motor. 

 

There are primarily two types of motors, those that use AC and those that use DC.

In typical DC motors, there are three major segments, the rotator (armature) which is a coil through which electricity is allowed to flow, creating a rotating magnetic field against the field generated by the stator. Commutator rings are split rings connected to the coils and are insulated from each other. The commutator rings, which are connected to the power source, ensure that the rotation of the coil is in the same direction by only allowing the current to flow in one direction. The brushes are connected to the commutator rings and the power source. When the brush passes through the insulated gap between commutator rings, it resets the flow of electricity until the next segment of the commutator ring passes through it, thus ensuring a steady flow of magnetic current and torque in the same direction.

 

AC motors have become the standard across the industry as companies like Tesla, Nissan, and Chevrolet, among others. There are two types of AC motors, the asynchronous and the induction motor. In the former, the magnetic field generated in the stator is one step ahead of the field produced in the rotator, as a result of which the rotator tries to become aligned with the stator, creating a spinning motion. The other form of AC motor is the synchronous motor, in which the rotator is a permanent magnet (made from metals like neodymium) that creates a permanent magnetic field.

In an AC motor, the current from the battery is first converted into AC with the help of an inverter. This AC is then fed into the stator creating the electromagnetic field that is opposite to the field created by the rotator. This difference in magnetic polarity then drives the motor, the torque produced by which is converted through a gear set multiplication powering the Electric Vehicle to the ludicrous speeds that have become synonymous with them. 

 

 

The EV job market around the world is seeing an increase in recruitment activity as firms are desperate for talents to join their companies. To start your career in the EV industry, you have to understand how the different parts of the powertrain of an Electric Vehicle work, as briefly highlighted in this article, and how various parts of the EV interact with each other. Skill-Lync has designed industry-relevant programs that will not only train you in the software skills required for you to start your career by training you in various industry-relevant projects that simulate real-life problems.