A new gate commutated turn-off thyristor and companion diode for high power applications

Conventional gate turn-off (GTO) thyristors require costly dv/dt and di/dt snubber circuits as well as bulky gate drive circuits. Hard turn off in which all of the main current is commutated to the gate drive circuit with a turn-off gain of one has been looked upon as a way to reduce the dv/dt limitations of the conventional GTO. The new gate commutated turn-off (GCT) thyristor is optimized for this mode and is coupled with a low inductance gate drive circuit to greatly reduce the di/dt limitation and allow operation without a dv/dt snubber. A new soft recovery diode has been developed to provide the capability necessary to apply the superior characteristics of the new GCT in actual application.