Fault-tolerant control strategy of a five-phase permanent magnet synchronous machine used for EV

The torque ripple is large when multiphase fault-tolerant permanent-magnet synchronous machine (PMSM) operates under fault conditions. An optimal current control strategy is proposed to reduce the torque ripple as multiphase machine works under fault conditions. Torque and torque ripple of multiphase machines under fault conditions were analyzed based on the phasor diagram of torque ripple. The optimal input currents for the remaining healthy phases were calculated to achieve a minimum torque ripple. The optimal current control strategy was verified by combined simulation, and the simulation results indicate that the torque ripple under fault conditions is reduced by more than 50% after adopting the proposed optimal current control strategy.