Open‐Circuit Fault‐Diagnosis Method for PMSM Inverter Systems Based on Quasi‐Z‐Source Network Characteristic Analysis

Open‐circuit (OC) faults in the switching devices of quasi‐Z‐source inverters (qZSI) can severely degrade output power quality and cause abnormal operation of permanent magnet synchronous motor (PMSM) systems. However, existing diagnostic methods mostly rely on signal analysis of output current and voltage, neglecting the distinctive topological characteristics of the qZS network, which limits diagnostic robustness and specificity. This article proposes a fault‐diagnosis method for inverter OC faults based on the characteristic analysis of the qZS network. The proposed approach exploits the differential response of the duty cycle under various operating modes during fault conditions, extracts the boost‐inductor voltage residuals for fault detection, determines the faulty phase through instantaneous current‐vector angle analysis, and locates the specific faulty switch using the average current over one electrical period. Compared with traditional voltage‐residual or deep‐learning‐based methods, the proposed method requires no additional sensors, achieves higher robustness, and involves lower computational complexity. Finally, both simulation and experimental results verify the feasibility and accuracy of the proposed method.