Investigation of GTO Turn-on in an Inverter Circuit at Low Temperatures using 2-D Electrothermal Simulation

Abstract

GTO (gate-turn-off-thyristor) turn-on failure in inverter circuits for traction drives is investigated by mixed-mode 2D electrothermal device and circuit simulation. Whereas GTO turn-off failure has already been analysed extensively in the past, in this paper a novel turn-on failure mechanism at low temperatures is analysed. The turn-on failure is due to a decreased carrier lifetime at low temperature with resulting increased latching current. As a consequence at low load current and low triggering current large parts of the device area do not latch while other parts with somewhat higher carrier lifetime or deviating doping concentration have to sustain a very high current density at high voltages. It is essential for this destruction mechanism to take into consideration the distributed resistance of the gate metallisation and its contact resistance.