Short circuit analysis and protection of power module IGBTs

n this paper, the failure modes of power module IGBTs have been experimentally studied by focusing on the short-circuit behaviour of the devices, with reference to the hard switching fault (HSF) and fault under load (FUL) types of fault. In particular, the current ringing phenomenon, having an important influence on the short circuit behaviour of the IGBTs, has been investigated by taking in account for the gate driving conditions. A suitable circuit which performs the fault protection of IGBTs by taking into account for the large voltage spikes and oscillations at turn-off is proposed. Due to such an influence of current oscillations on the collector voltage of the IGBT, a low-pass filter designed at the gate side of the device has been provided to damp the gate voltage oscillations and, consequently, the collector voltage ringing. By this way, full protection of the IGBT in short-circuit conditions has been successfully achieved