Week 4 Session 5

DC-DC Converter

• DC-DC converter is an electronic circuit that converts DC voltage from one voltage level to another. It can be step up or step down of voltage.
• This type of converter is also known as chopper.
• The electric components inside the vehicle vary in their voltage requirements, with most running on much lower voltage. This includes radio, dashboard readouts, air conditioning, and in-built computers and displays.
• It can be unidirectional or bidirectional.
• Most of the components are bidirectional, allowing power to go from the battery to the inverter, which rotates the motor.
• When decelerating, the vehicle's momentum turns the motor, which is now acting as a generator, drives power back through the inverter and charges the battery.
• DC-DC converter converts higher voltage DC power from the traction battery pack to the lower-voltage DC power needed to run vehicle accessories and recharge the auxiliary battery.

ii. DC-AC Convetrer

• DC-AC converter change a dc input voltage to a symmetric ac output voltage of desired magnitude and frequency.
• This type of converter is also known as inverter.
• The inverter can change the speed at which the motor rotates by adjusting the frequency of the alternating current.
• When the vehicle has to be accelerated, the accelerator pedal sends a signal to the controller which adjusts the vehicle's speed by changing the frequency of the AC power from the inverter to the motor.

iii. AC-DC Converter

• AC-DC converter takes a harmonic AC input and converts it to a DC output.
• These concerters are also known as rectifiers.
• Inverters are used in Ev/Hev mainly for the on-board charging purpose. Since the charging stations use AC power to charge the vehicle and the battery stores DC power, rectifiers are used to convert AC-DC.