A Robust Diagnosis Method for Power Switch Open-Circuit Faults in Voltage-Source Inverters Under Transient Conditions

Fault diagnosis is essential to ensure the reliability and continuous operation of power converter systems. Despite significant progress over the years, the applicability of diagnosis methods in transient processes remains limited, hindering their practical application, especially in transportation electrification. To tackle this issue, a diagnosis method for voltage-source inverter power switch open-circuit faults with superior transient adaptability is proposed. The method firstly transforms the three-phase current into a two-phase orthogonal coordinate system and then analyzes the current vector trajectory under different fault conditions. A fast fault detection method is then developed based on trajectory analysis. Furthermore, the trajectory is converted into a two-dimensional binary matrix, which is then recognized by a lightweight Convolutional Neural Network to locate the fault. Compared to existing methods, the proposed method significantly expands the diagnostic range while maintaining high accuracy, particularly excelling in handling transient processes. Physical experiments have verified the method’s performance across a wide range of operating conditions.