An Igbt Inverter Protection And Fault Diagnosis

Due to the impact of IGBT's stability and reliability, the engineering problem of power device such as easy failure and short life are hard to void. Thus, the protction circuit of IGBT and the inverter fault diagnosis algorithm based on waveform similar matching, which are very useful to improve life and efficientcy of device and to reduce fault rate, are proposed in this paper.After analyzing the current, voltage and thermal characteristics of 50kVA APF, driver and over-current protection circuit, RCD subber circuit, online and real-time overheating detection circuit based on PTC thermistor were designed. The universal dirver and over-current protection module had a general-purpose peripheral interface circuits and was suitable for 1200V-1700V IGBT applicable to less than 10kHz circumstance. The overheating detection circuit based on PTC thermistor with multi-response characteristics for different temperatures could send off alarm and close signal. The running results of APF prototype show that IGBT dirive and protection circuit were stability and met the needs of 50kVA APF.The fault diagnosis algorithm included classification and similarity measurement. First, feature vector of classification was extracted by wavelet transform and singular value decomposition. Then support vector machine was carried out to train the history fault waveforms and classify current fault waveform. Last, the similarity measurement between current fault waveform and classified history fault waveforms were achieved by wavelet matrix transform based on uniform basis. Experiment results, comparing proposed method with plain wavelet and wavelet SVD, show that proposed methods were better then other two methods in anti-noise ability and accuracy of similarity value.The running result of APF prototype and software and hardware practice of the fault diagnosis algorithm proof the effectivness of IGBT protection and laid the foundation of the fault diagnosis based on fault waveforms.