Week 4 Session 5

Applications of Power converters in an Electric vehicle

DC to AC converters ( Inverters)

The use of inverters can increase or decrease the power or torque of the motor by adjusting the amplitude of the signal.

It plays a significant role in capturing energy from regenerative braking and feeding it back to the battery. The key component is that it has a direct impact on on-road performance, driving range, and reliability of the vehicle also as a consequence of their weight and size.

The output voltage waveform of ideal inverters should be sinusoidal. However, the waveform of practical inverters is non-sinusoidal and contains certain harmonics.

DC to DC converters (Choppers)

A step-up converter, which turns a low-voltage input into a high-voltage output, or a step-down converter, which does the exact opposite.

In electric vehicles that use a DC motor, the running motor can use up to three times the voltage provided by the battery. With the help of the right converter, we can bridge this gap without having to use a larger, heavier battery.

Isolated DC-DC converters

The input and output stages are separated and there is a presence of a transformer which can further reduce (or increase) the output voltage apart from being done by the duty cycle. Forward, Flyback, Half bridge, Full bridge, and Push-pull converters fall under this category.

The amount of power flow between the input and the output can be controlled by adjusting the duty cycle (ratio of on/off time of the switch). Usually, this is done to control the output voltage, the input current, and the output current or to maintain constant power.

Auxillary loads involved in Electric vehicle:-

Horn, Air conditioning system , Lighting system( Headigh, Indicators, Tail light etc) , Powertrain electronics cooling , Power steering

For Horn which requires DC less than 10 V DC-Dc converter is used