High Speed, Snubberless Operation of GTO's using a New Gate Drive Technique

GTO's can be operated at currents well beyond the rated ^Itcsm 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 (RBSOA) that extends to the VjrxII| on the voltage axis and beyond the Itcsm ^{0,1 tbe} current axis. Storage time is reduced to a few tenths of a μδβοοηά 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 GTO's becomes practical with this technique due to the short storage times and low external snubber losses.