High-speed snubberless operation of GTOs using a new gate drive technique

Gate turn-off thyristors (GTOs) are operated at currents well beyond rated I_tcsm without turn-off snubbers by use of a gate drive circuit that is capable of very high rates of rise of reverse gate current. This results in a very large rectangular unsnubbed reverse-biased safe operating area that extends to the V_drxm on the voltage axis and beyond the I _tcsm on the current axis. Storage time is reduced to a few tenths of a microsecond and the inductance required for paralleling is reduced by an order of magnitude. Elimination of the turn-off snubber capacitors allows protective circuit trip levels to be set closer to the device ratings and reduces the energy loss in the turn-on snubber. The size of the turn-on snubber inductor can be significantly reduced. High-frequency operation of GTOs becomes practical with this technique due to the short storage times and low external snubber losses