Seeking Assistance with 7KW PFC Circuit Based on STEVAL-7BIDIRCB Design

[Waldon]

Dear ST Community Members,

I have built a 7KW three-phase interleaved totem pole PFC circuit (based on the schematic of STEVAL-7BIDIRCB, retaining only the PFC section). The firmware was generated using ST eDesignSuite's "FW download" tool. Before power-up, I verified the ADC readings for input voltage/current and output voltage/current sampling, all of which matched the calculated values.

Current Observations:

1. Scenario A:

   • Apply 230V/50Hz AC power first → Power on the STM32G474 MCU

   • Result: Output stabilizes at 325V (rectified voltage), control board yellow LED lights up, and can't start.

2. Scenario B:

   • Power on the STM32G474 MCU first → Apply 230V/50Hz AC power

   • Result: Output rises from 0V to 230V, holds for ~300ms, then the circuit breaker trips.

Additional Notes:

• Tripping device: Schneider Electric C16 30mA RCCB (Residual Current Circuit Breaker)

• No components on the PFC board show visible damage

Could anyone kindly advise on potential root causes for these behaviors? Any insights or suggestions would be greatly appreciated!

Thank you in advance for your support!