Active gate control strategy of series connected IGBTs for high power PWM inverter

This paper describes an operation of series connected IGBT gate drive circuit with a closed loop voltage control in high voltage inverter applications. The purpose of voltage control is to instantaneously limit large overvoltage applied to certain IGBTs in inverter valves during switching transients and off-state IGBT voltages and to maintain the voltage to an acceptable level. The performance of the gate drive circuit is examined experimentally by the series connection of four different rated IGBTs with conventional snubber circuits. The experimental results show the voltage balancing by the voltage control with wide variations in imbalance conditions.