Minimising snubbers for high-current emitter-switched transistors

High-power emitter-switched transistors have been operated at 20 kHz and 80 A off 600 V, using voltage clamps instead of shunt snubbers. Under these conditions, snubbing is the dominant source of switching-related power loss and transistors deadtime. An analysis of series snubbers reveals configurations conducive to minimal reset-time and power-loss. Cascode switches operating at high-current ideally require adaptive voltage-clamps which clip at current-dependent voltage levels; practical realizations of such clamps are given.