Short current protection circuit for automotive motor inverters application based on GaN transistors

Ensuring the reliability and safety of power converters based on wide band gap (WBG) semiconductors is a critical issue. The former exhibit high critical fields, consequently, and unlike silicon devices, when the devices are stressed a catastrophic failure may erupt before avalanche takes place. For this reasons, short current protection circuit must exhibit nanosecond level detection time in order not to exceed the safe switching operation area of the device and has to ensure smooth turn-off. In this paper, an original derivative pulsed-current sensor in conjunction with the fast response 2-stage shutdown circuit is evaluated for various short-circuits. The protection circuit is developed and tested with the half-bridge converter evaluation board for 650 V / 80A GaN devices in various short circuit conditions.