直流断路器用IGBT正向恢复特性实验建模

直流断路器是柔性直流电网故障清除的主流手段。混合式直流断路器动作前，转移支路IGBT处在正栅极电压的零电压零电流状态，当转移支路电流开始上升时，由IGBT正向恢复过程产生的集-射极电压过冲一旦满足IGBT过流监测判据，将会引起保护误动进而降低装备运行可靠性。针对直流断路器工况下IGBT出现的正向恢复现象，通过建立的IGBT大电流开通实验平台获取了不同电流上升过程中IGBT集-射极电压波形，基于分阶段数学表征建立了能够反映IGBT正向恢复特性的I-U映射关系。与实测结果相比，该模型计算所得的集-射极电压峰值相对误差小于10%，高于过流监测阈值电压的持续时间相对误差小于15%，可支撑直流断路器所用IGBT的过流监测判据的合理制定。

Experimental Modeling of Forward Recovery Characteristics of IGBT for DC Circuit Breaker

DC circuit breaker is the main means to clear the faults in VSC-HVDC power grid. Before action of the hybrid DC circuit breaker, the IGBT in the transfer branch is in a state of zero voltage and zero current. When the current of the transfer branch begins to rise, and once the voltage overshoot of collector-emitter produced in the forward recovery process of IGBT meets the IGBT's over-current monitoring criterion, the protection will malfunction, consequently reducing the operating reliability. Aiming at the forward recovery phenomenon of IGBT, a high-current turn-on experimental platform of IGBT is built to obtain the IGBT’s collector-emitter voltage waveforms corresponding to different current waveforms. Based on the staged mathematical fitting, an I-U mapping relationship that reflects the forward recovery characteristics of the IGBT is established. Compared with the experimental results, the relative error of peak collector-emitter voltage is less than 10%, and the duration relative error of over-current monitoring threshold voltage is less than 15%. The model can help to reasonably formulate the over-current monitoring criterion of IGBT used in DC circuit breaker.