Let’s get to know about the electric vehicle power-train…

August 3, 2019 Rakesh Ray 1967 Views

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Power-train of an electric vehicle

Image: AVL Electric Axle

Our mind is tuned in such a way that they learn and memorize the things when we compare one thing with another. So, here to give you an overview of the electric vehicle I will compare with the existing IC engine (in general petrol or diesel vehicle) vehicle.

Basically, any vehicle is the final combined form of power-train, chassis, outer shell (vehicle body) and some electromechanical systems. so the main difference between diesel/petrol vehicle and electric vehicle is related to the power-train unit.

The power-train of the diesel/petrol car is having:

→Internal Combustion Engine

→Clutch system

→Gearbox

The engine is run by petrol or diesel which is filled from outside in the fuel tank of the vehicle. The engine generates the power which is transmitted to the gearbox through the clutch systems. Gearbox does it works, and power is transmitted to the wheel through the propeller shaft and differential.

But the powertrain (power plant) unit is completely different for an electric vehicle.

The powertrain of an electric vehicle is having:

→Inverter

→Electric Motor

→Gearbox

→Battery pack

Image: Electric Vehicle Power-train

So, basically, here the IC engine is replaced with the electric motor and fuel tank is replaced with the high voltage battery pack. Inverter required here to convert the battery’s DC current into 3 phase AC current. Inverter is also used during the battery charging.

Jaguar i-pace (Image Credit: https://www.jaguar.com/jaguar-range/i-pace/)

Now you will be eager to know more about the power-train of the electric vehicle. So, let’s know more about the inverter, motor, gearbox and battery pack-

Inverter Technology:

Inverter system is basically a combination of few electro-mechanical subsystems which are described below-

Rectifier: Converts the alternating current (AC) into direct current (DC).

When the vehicle is charged from a home electrical grid (e.g. 220 V).

DC-DC Converter: responsible for the lowering of the high voltage (e.g. 400 V) to the low voltage network (12 V)

Inverter: controls the electric machine speed and torque by converting the direct current from the battery into the alternating 3-phase current for the electric machine.

When the vehicle is in energy recuperation phase (braking) the inverter is doing the opposite conversion, from 3-phase AC to DC

Electric Motor:

We give electricity into it at one end and an axle (metal rod) rotates at the other end giving you the power to drive a machine of some kind or say it give drive to the gearbox attached to it in an electric vehicle.
Generally, we give 3 phase AC current to the motor and this AC current is converted from the battery DC current with the help of the inverter. We will learn more about the electric motor in the coming posts.

Battery:

A battery which is used as the energy source or energy reservoir in the electric car is made by connecting so many cells in series or parallel. A cell may be of different type like –

These any one of the cells are used to connect into series or parallel to make one module.

Now, these modules are connected to each other and this way a complete battery pack gets ready.

Nissan Leaf battery pack

Note:

1) One special electronic device called BMS (battery management system) is used onboard to monitor the charging and discharging of the battery. It also monitor the battery temperature.

2) The gearbox used in the electric vehicle is much simpler than the usual 5 speed or 6-speed gearbox used in now a day diesel or petrol car.

Below image is just illustration for these all the subsystem placed into one of the electric cars:

Images credit: https://www.jaguar.com/jaguar-range/i-pace/

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