Low-leakage drive for optically-triggered high-power SiC emitter turn-off thyristors

In this paper a new low-leakage drive for SiC emitter-turn-off (ETO) thyristors for power rating of 15-kV and 100-A is presented. Conventional ETOs suffer from the turn-on leakage current. Turn-on leakage current is caused by the false activation of the turn-off path in the gate contact of the thyristor. This is due to the high slew rate of the current and parasitic inductances in the turn-on commutation path. This leakage current decelerates the switching action, increases the switching loss and generates electro-magnetic noise. The proposed method reduces the leakage current by adding only a low-power Zener diode in the gate path of the thyristor, enhancing the switching performance and reducing the switching loss. The proposed drive method is investigated and verified through simulation results.