Active Clamping Circuit with Status Feedback for HV-IGBT

Active clamping circuit can effectively suppress the overvoltage of series-connected insulated gate bipolar transistor (IGBT). However, long duration operations and frequent actions of active clamping circuit would lead to high losses of the circuit and IGBT, which seriously imperils the efficiency and safety of the system, especially in the applications of high voltage IGBT (HV-IGBT). In this paper, a novel active clamping circuit with status feedback is proposed for series-connected HV-IGBTs. A high speed status feedback sub-circuit is designed for transforming the operation status of active clamping circuit into optical signal and transferring it to control system. According to the feedback signal, microcontroller is able to activate the protection procedure or regulate the drive signal timely in order to restrain the action of active clamping circuit. Experimental results verify the validity of the proposed circuit.