An active gate drive circuit for high power inverter system to reduce turn-off spike voltage of IGBT

This paper presents a new gate drive method for high power IGBT to reduce the turn-off spike voltage which is appeared between collector and emitter. In the power circuit of inverter, there is a commutation loop stray inductance between the dc-link capacitors and IGBTs. It affects the turn-off spike voltage of IGBT. In general, snubber circuits are used to control the spike voltage but they are consists of passive components result in the limitation to reduce the spike voltage. In this paper, a new active method is proposed and based on the saturation voltage characteristics of IGBT which is related with collector current and collector-emitter voltage. In order to reduce the spike voltage, gate current is controlled in the active region during the turn-off. The proposed method is implemented with 220 kW inverter and verified by the experimental results.