Comparative Study of Negative Sequence Current-based and Current Residual-based Online Diagnosis Method for Inter-turn Faults in PMSM Drives

When the inter-turn faults (ITF) occur, the motor short-circuit current increases sharply, affecting the balance of the motor system, prolonged operation under this condition can cause irreversible damage to the entire motor system. Therefore, early diagnosis of ITF is critical to ensuring the reliability of the motor system. This article focuses on two kinds of fault diagnosis methods based on signal processing and analytical model, it compares and analyzes two kinds of fault diagnosis strategies based on negative sequence current and current residual, respectly. Initially, mathematical models representing both the healthy and fault states of the permanent magnet synchronous motor (PMSM) are established in a synchronous rotating reference frame. Then, the second-order generalized integrator (SOGI) is utilized to extract the negative sequence components in real-time, while current residual is obtained through an observer. Based on theses, corresponding fault detection indicators are proposed. Finally, a fault test platform is constructed to evaluate and compare the performance of the two diagnostic methods in terms of fault detection accuracy and robustness.