New design approach for ultra high power GCT thyristor

Turn-off capability is a major concern when designing ultra high power, large size GCTs (gate commutated turn-off thyristors). Unlike small size GCTs, which have a high turn-off capability, conventional large size GCTs have a low turn-off capability that is not proportionate to its high power. With the help of computer simulation and test sample evaluation, we developed a new design approach for ultra high power GCTs with improved turn-off capability. Turn-off simulation suggested that the low turn-off capability of large size GCTs is related to the nonuniformity in the GCT chip design. Optimizing the GCT chip uniformity following our new design approach resulted in large size GCTs with higher turn-off capability when compared with the conventional approach.