High power gate-controlled switch

The ratings of GCS's have remained around 10 amperes and 600 volts since the early 1960's. The problem of increasing the device's capability is therefore reviewed. Experimental results show that turn-off is governed by the diversion of the anode current through the gate,the sequence of junction recovery, the optimum gate drive timing, and the condition of a low impedance drive voltage below the gate avalanche point. Furthermore, the scaling-up for high current assumes that the total current is shared by each elemental area at all times, Tests revealed that nonuiformity leads to shifting of load current during turn-off into on area which causes failure. With due consideration of these factors, a practical design and process for the high power GCS were developed. Data on developmental 50-ampere GCS's are presented.