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.