An Open-Circuit Fault Diagnosis Algorithm Based on Signal Normalization Preprocessing for Motor Drive Inverter

In this article, an open-circuit (OC) fault diagnosis algorithm for power switch in the motor drive inverter system is proposed, which uses signal normalization preprocessing to deal with the current fluctuation caused by the load change. For the proposed fault diagnosis algorithm, first, the three-phase currents are sampled by the sliding window, which can improve the timeliness of diagnosis. Then, the sampled data are preprocessed by the variable modulus length normalization to eliminate the influence of the load change. Especially in the transient state, the information of the data feature is retained and the impact of load change is removed. Moreover, the frequency-domain feature of the data is extracted by the discrete Fourier transform (DFT). Finally, the dimension of the features is reduced by the principal component analysis (PCA) method and its contribution graph is used to locate the fault insulated gate bipolar transistor (IGBT). Moreover, the method can overcome the misjudgment of IGBT failure caused by transient currents when the load changes in the drive system. The simulation and experiment results show its effectiveness and timeliness in the OC fault diagnosis of the inverter.