Analysis and Suppression of Torque Harmonics in PMSM with High Resistance Connection Fault

High resistance connection (HRC) fault is a common electrical fault in motor systems that will lead to performance degradation or even system failure. To gain a deeper understanding of the operating characteristics of permanent magnet synchronous motors (PMSMs) under an HRC fault and to mitigate its adverse effects, this paper analyzes the harmonic characteristics of the electromagnetic torque caused by such faults and proposes a fault-tolerant control (FTC) method. First, based on symmetrical components theory, it is shown that the second and fourth harmonic components in the electromagnetic torque are indicative of HRC fault. Then, a fault-tolerant control method combining an adaptive notch filter (ANF) and a resonant sliding mode controller (RSMC) is proposed to suppress torque harmonics and enhance system robustness. Finally, the accuracy of the proposed analytical method and the effectiveness of the control strategy are validated through both simulations and experiments, demonstrating that the method can significantly improve motor performance under fault conditions without requiring additional hardware.