I have an three phase inverters (for induction motor) which use IGBTs(without protection circuitry). The problem is every other day, these IGBTs are getting blown out. So, I am thinking of designing protection circuitry for IGBTs. The inverter is driven by 300VDC and the IGBTs are driven by PWM signals from IR21362 driver IC. But I am really stuck on how to design a proper protection scheme. I guess there out to be standard protection methods out there. Your expert advices on this will really be appreciated.