串联谐振变换器IGBT开路故障检测方法

IGBT open circuit fault diagnosis method for series resonant converter

针对串联谐振变换器IGBT开路故障检测问题,根据故障前后断续谐振电流波形变化特征,提出了一种故障在线检测方法。首先,通过分析变换器的等效电路,得到了单个IGBT开路故障时的谐振电流表达式。从故障机理可知,当单个IGBT开路后,输出电流的平均值减半,同时谐振电流波形在一个开关周期内比正常工况时减少了一个半波。然后,根据故障时谐振电流波形特征,设计了相应的故障检测电路,并通过DSP控制器在线检测谐振电流整形后的方波跳变沿,有效地诊断出了IGBT开路故障,由此证明了所提方法的正确性。

Aiming at the IGBT open-circuit fault detection problem of series resonant converter,an on-line fault diagnosis method is proposed according to the change of the discontinuous resonant current waveform before and after the fault.By analyzing the equivalent circuit of the converter,the resonant current expressions of the single IGBT open circuit fault are obtained.The fault mechanism shows that when a single IGBT open circuit fault occurs,the average value of the output current is halved and the resonant current losses a half-wave than in the normal operating condition.According to the characteristics of resonant current waveform at fault,a hardware circuit for fault detection is designed,which can effectively diagnose the IGBT open circuit fault by detecting the edge of the square waveform reshaped from the resonant current based on the DSP controller.