7 High-Voltage Bias, Redundant Supply

A traction inverter system often requires a high-voltage power supply, which converts power from the high-voltage battery and connects to the low-voltage side creating a redundant power path and increasing safety. This high-voltage power supply can be required to start up when the input voltage is as low as 50 V, and also must able to operate as high as 1 kV for an 800-V battery. A low start-up voltage can occur after a vehicle crash or if a traction inverter malfunction results in a separation of the high-voltage battery. The motor starts rotating and acts like a generator, which induces a non-controlled voltage into the DC bus. To control the voltage so that the voltage does not exceed 50 V (touch safe), the auxiliary power supply has to turn on and power up safety-relevant circuits that can discharge the DC link caps (active discharge) or actively short circuit the motor.

TI offers various reference designs to fulfill this requirement:

1. Texas Instruments, UCC28C5y-Q1 EVM: 40V – 1kV Input, 15Vout, 40W PSR flyback
2. Texas Instruments, TIDA-01505 – Automotive 40-V to 1-kV input flyback reference design supporting regenerative braking test
3. Texas Instruments, PMP22288 – 15-W flyback reference design for automotive inverter power
4. Texas Instruments, PMP10200 – Ultra-Wide Input Voltage Range PSR Flyback Converter Reference Design