Enhanced Fault-Tolerant Control for Torque Ripple Reduction in Dual Three-Phase PMSMs Considering Back EMF Harmonics

With fault-tolerant operation of dual three-phase permanent magnet synchronous machine (DTP-PMSM), the torque ripple deteriorated by back electromotive force (EMF) harmonics is harmful for high precision servo control field in aviation. This article proposes an open-circuit fault-tolerant control strategy to optimize the torque ripple caused by back EMF harmonics. Firstly, the mechanism of torque ripple deterioration is investigated by using magnetomotive force synthesis theory. Then, harmonic components of torque ripples are analytically derived based on the back EMF harmonic distribution. Subsequently, the fault-tolerant current references are newly deduced for both isolated and single neutral point winding configurations by using the torque ripple optimization algorithm. However, for the single neutral point configuration, the copper loss is greatly increased when using the optimized fault tolerant current references. Therefore, a trade-off point is established to balance torque ripples and copper loss. The proposed strategy effectively suppresses torque ripple within a compact framework and demonstrates high practical feasibility. Finally, the effectiveness and superiority of proposed strategy is verified through experimental results on a 48-slot and 22-pole DTP-PMSM.