Hello all
Now,the IGBT on my board has been burned by a strange fault.
Specific working conditions:
When the motor is running at 1200 rpm, the bus relay is suddenly disconnected.Then,the bus voltage(500V) dropped and the system detected a bus voltage undervoltage,so the PWM signal is turned off by the undervoltage signal。After this the PMSM motor entered the state of power generation,to make increase the bus voltage slightly.This causes the system to transition from an undervoltage condition to a non-undervoltage condition.During this short period of time, the system was considered normal(non-undervoltage condition), and the MCU began to output a PWM signal to drive the rotating motor again.when the PWM was output again,I found the bus voltage increased abnormally, and it rose from 400 volts to 1200 volts.I wonder why the bus voltage suddenly rises abnormally?
If you are not clear about my description, I can use waveforms to show it:
The whole waveform captured by me(zoom out):
Waveform Captured by me(zoom in):
So,Why does driving a rotating motor in a power generation state by SVPWM cause the bus voltage to rise dramatically?Or my analysis is not rigorous, missing something?
Thank you to everyone who discussed this.