IGBT串联电压失衡机理研究

Study on unbalance mechanism of IGBT series voltage

在高压开关场合的IGBT串联应用中,由于IGBT本身、电路参数、器件温差、驱动信号差异、寄生电容差异等因素的影响,使得IGBT串联使用中存在电压失衡导致高压击穿的问题,影响整个系统的正常工作。因此,文中就导致电压失衡的因素进行分析与研究,针对造成电压失衡的影响因素进行理论分析,对IGBT串联电压失衡机理进行了较为深入的研究,并提出平衡串联IGBT串联动态电压的方法。通过分析得出引起串联IGBT动态电压失衡的根本原因有三方面:动态阻抗不一致导致的动态分压不一致;开关时刻及速度不一致;寄生电容引起的分流导致各级IGBT流过的电流不一致。

In the application of the insulated gate bipolar transistor(IGBT)series in the high⁃voltage switch occasions,there is a problem of high⁃voltage breakdown caused by voltage imbalance in series application of IGBT due to the influence of IGBT itself,circuit parameters,device temperature difference,driving signal difference,parasitic capacitance difference and other factors,which affects the normal operation of the whole system.Therefore,the factors that lead to voltage imbalance are analyzed and studied,and the influencing factors of voltage unbalance are analyzed theoretically.The in⁃depth study on the mechanism of IGBT series voltage imbalance is carried out,and a method of balancing series IGBT series dynamic voltage is proposed.Three fundamental reasons for the unbalance of series IGBT dynamic voltage are concluded.They are dynamic partial pressure inconsistency caused by dynamic impedance inconsistency,switching time and speed inconsistency,and inconsistency of currents flowing from all level IGBTs,which is produced by the shunt caused by parasitic capacitance.