A Fast Open-Circuit Fault Diagnosis Method for IGBT of Inverter Based on DC Output Current Rate of Change

Three-phase inverters are the important part of the DC zonal electrical distribution subsystem in the integrated power system, the fault of IGBT will lead to the decline of output power quality and even threaten the safety of the system. In order to improve the reliability of the system, a fast open-circuit fault diagnosis method for IGBT of inverter is proposed. Firstly, the switching state model of a typical three-phase inverter is established, and the expressions of DC output current and its rate of change under different switching states are obtained. Then, the switching function of the switch tube under different fault states and its influence on the output current of the DC side are analyzed, the characteristic parameters corresponding to different types of faults are extracted, and the rapid fault diagnosis scheme is designed. The fault diagnosis method proposed is based on the sampled signal of the control module, and the fault characteristic parameters are calculated in real time, and the state estimation process is not affected by the circuit working conditions. There is no need to add additional sensors; Finally, the feasibility and accuracy of the proposed method are verified by simulation and experiment. The proposed method can accurately locate the fault within one to two switching cycles after the fault occurs.