Interturn Short-Circuit Fault Diagnosis Method of PMSM Servo System Based on High-Frequency Negative Sequence Components

The working environment and operating states of the permanent magnet synchronous motor (PMSM) servo system make stator winding interturn short-circuits (ISCF) more likely, and the time-domain aperiodic fault characteristics also poses challenges for fault diagnosis. To address this, this paper proposes a high-frequency negative sequence component-based fault diagnosis (HFNSC-FD) method. The rotating high-frequency (HF) current injection introduces symmetric HF components into the system, and second-order generalized integrators are used to extract the HF response. Then, the HF negative sequence component is constructed through signal delay, forming a fault characteristic that maps fault severity. The method determines whether a fault has occurred by comparing the fault characteristic with a predefined threshold and locates the faulty phase using the minimum phase difference. This diagnostic method is independent of PMSM operating conditions, significantly improving fault detection and location reliability. Compared with the existing method, the proposed method offers higher detection sensitivity and greater robustness in fault location. Extensive experimental results validate its effectiveness.