Optimization of the turn-off performance of IGBT at overcurrent and short-circuit current

The maximum safe collector current of an insulated-gate-bipolar transistor is limited by the junction temperature and the overvoltage due to the parasitic inductance at turn-off. In applications, which require a high utilization of the rated collector-emitter breakdown voltage of the IGBT, the gate control has to ensure low loss turn-off at nominal current and low overvoltage turn-off at overcurrent and short-circuit current. A two-stage gate control for the IGBT is presented, which allows a reduction of the overvoltage at overcurrent turn-off without increasing he switching losses at nominal current. A further reduction of the overvoltage is achieved by a current dependent changeover of the gate resistance. The measure of the current is the Miller-plateau of the gate-emitter voltage. The experimental results prove that it is possible to achieve a considerable reduction of the overvoltage at overcurrent and short-circuit current