非正弦反电势五相永磁电机开路故障容错控制研究

A Fault-tolerant Control for Five-phase Permanent Magnet Synchronous Motor With Non-sinusoidal Back-EMF Under Open-circuit Fault

与正弦波电机相比,具有非正弦反电势波形的多相电机可提升转矩密度,但容错运行时,反电势谐波会产生额外的转矩脉动。为此,该文提出一种非正弦反电势五相永磁同步电机缺相容错控制策略。基于单相开路故障下转矩方程,推导平稳运行时同步坐标系下的电流表达式,给出利用谐波电流抑制转矩脉动的理论依据;并提出在同步旋转坐标系下注入低阶谐波电流,抑制由3次谐波反电势引起的转矩脉动。为了求解最优谐波电流,分别在最小铜耗或最大转矩模式下协同优化电流系数。相比现有方法,该方法在最小铜耗模式下,能够产生相同的定子铜耗;在最大转矩模式下,能够提高转矩输出能力。最后,通过五相永磁同步电机的缺相容错实验,验证所提控制策略的准确性及有效性。

Multi-phase machines with back-EMF harmonics can be utilized to improve the torque density.However,back-EMF harmonics will induce additional torque ripples under post-fault operation.In this paper,a fault-tolerant control strategy for five-phase permanent magnet synchronous machines with non-sinusoidal back-EMF under open-circuit fault is proposed.Based on the torque equation under single-phase open-circuit fault,the general closed-form solution for disturbance-free operation is derived and the theoretical basis for suppressing torque pulsation with harmonic current is given.Therefore,the low-order harmonic currents are injected in the synchronous frame to suppress the torque pulsation caused by the 3^(rd) harmonic back-EMF.To obtain optimal solution,two operation modes are applied,such as minimum copper loss(ML)or maximum output torque(MT),to simultaneously optimize harmonic current coefficients.Compared with the existing method,the proposed method could produce the same copper loss under ML mode and effectively improve torque output capacity under MT mode.Finally,the experiment results for five-phase permanent magnet synchronous machines under postfault operation verify the accuracy and effectiveness.