Short-circuit fault-tolerant control for five-phase fault-tolerant permanent magnet motors with trapezoidal back-EMF

When a short-circuit fault occurs in a phase, the faulty phase needs to be removed artificially from the system because of the loss of the capability to generate torque. In this case, both the short-circuit current and phase-loss fault would generate additional torque ripples. In this study, a novel fault-tolerant control strategy is introduced to achieve low torque ripple operation of five-phase fault-tolerant permanent magnet synchronous motors with trapezoidal back electromotive force (FTPMSM-TEMF) in the event of a short-circuit fault. The key concept of this method is to compensate for the torque ripples caused by the short-circuit current and the adverse effect of the phase-loss. Based on the torque expression under fault conditions, the torque ripple caused by the short-circuit current can be offset by injecting a certain pulsating component into the torque expression in the phase-loss condition. This would result in smooth operation under fault conditions. Moreover, to track the fault-tolerant alternating currents, the model of the deadbeat current predictive control is extended and restructured for the fault condition. The effectiveness and feasibility of the proposed fault-tolerant strategy are verified by experimental results.