High power symmetrical GCT for current source inverter

Abstract

GCT (gate commutated turn-off thyristor) is a new high power device with snubberless turn-off operation which was developed in the mid-1990s, and is growing up to be the main device instead of GTO (gate turn-off thyristor) for high power application. For PWM current source inverters used in AC drive, symmetrical GCT with reverse blocking characteristics are expected. However, the symmetrical structure generally gives smaller turn-off capability compared with asymmetrical GCT, which has already been developed. This paper presents new GCT technologies, characteristics of 6 kV/4 kA symmetrical GCT and comparison of loss between current source inverter and voltage source inverter by using GCT.