Week 4 Session 5
Q.1 - Explain the various applications of Power converters in an Electric vehicle. For Example what type of converter will you use for Horn which requires DC and less than 10V. Likewise come up with different applications.
Sol - There are four types of power converters:
1. AC to DC Converter
2. DC to AC Converter
3. DC to DC Converter
4. AC to AC Converter (it is not used in EV)
AC to DC Converter
- An AC-DC converter is an electrical device that converts alternating current (AC) power to direct current (DC) power.
- AC-DC Converters are also called rectifiers, they convert the input AC voltage to variable DC voltage, then optimize it through a filter to obtain an unregulated DC voltage.
- Inverters are used in Ev/Hev mainly for onboard charging purposes. Since the charging stations use AC power to charge the vehicle and the battery stores DC power, rectifiers are used to convert AC-DC.
- This type of converter is commonly used in a variety of applications, including power supplies for electronic devices, battery charging systems, and motor drives.
DC to AC Converter
- The electrical circuits that transform Direct current (DC) input into Alternating current (AC) output are known as DC-AC Converters or Inverters.
- 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.
- They are used in power electronic applications where the power input is pure 12V, 24V, and 48V DC voltage that requires power conversion for an AC output with a certain frequency.
DC to DC Converter
- DC-DC converter is an electronic circuit that converts DC voltage from one voltage level to another. It can be a step up or a step down of voltage. This type of converter is also known as a 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.
- DC-DC converter will use for Horn which requires DC and less than 10V.