Key Influencing Factors on the Turn-off Transient Voltage Overshoot of IGBT in the Module of High Voltage DC Circuit Breaker

High voltage direct current (DC) circuit breaker based on fully-controlled electronic devices of insulated gate bipolar transistor (IGBT) is the key equipment for the multi-terminal flexible HVDC transmission engineering. The turn-off transient voltage overshoot of IGBTs in semiconductor module is a key problem needed to be paid attention in engineering. Taking the typical semiconductor module with IGBT full-bridge topology as an example, we firstly investigate the influence of busbar stray inductance in the module on the IGBT turn-off transient voltage overshoot. The influencing mechanism of busbar stray inductance at different positions on the IGBT turn-off transient voltage overshoot is revealed and the corresponding influencing sensitivities are obtained. Subsequently, based on the analysis about the turn-off mechanism of IGBT in high voltage DC circuit breaker applications, the key influencing factors, which include the physical character parameters of IGBT itself, and corresponding influencing laws on the IGBT turn-off transient voltage overshoot are obtained. Finally, the correctness of the analyses is verified by experiments. The research results show that the stray inductance of the capacitor branch in the module has the greatest influence on the IGBT turn-off transient voltage and it should be treated as the key optimization object. In addition to stray inductance, the gate oxide capacitance of IGBT, the knee voltage for the rapid rise of collector-emitter voltage during the turn off process and the gate driving resistance are key parameters influencing the IGBT turn-off transient voltage, and all of them have negative correlations with the turn off transient voltage. The conclusions obtained in this paper can provide guidance for the control of stray inductance in the module, the determination of driving resistance, and the selection or customization of IGBTs. © 2020, High Voltage Engineering Editorial Department of CEPRI. All right reserved.