直流断路器用IGBT正向恢复特性实验建模

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

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。

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 overcurrent 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.