Fault‐tolerant control technology of symmetrical six‐phase permanent magnet synchronous motor

Abstract

In comparison with three-phase motors, multiphase motors have garnered increasing attention owing to their high fault-tolerant ability. When the motor has an open-circuit fault, the stator combined magnetomotive force (MMF) changes, αβ and z1z2 subspaces are no longer decoupled, and the conventional vector control causes phase current distortion, harmonic current increase, and torque fluctuation of the motor. To address the aforementioned problems, first, the mathematical model of the common neutral symmetric six-phase permanent magnet synchronous motor in the static coordinate system is presented in this paper. Second, the transformation matrix of αβ and z1z2 subspace decoupling is proposed, and the corresponding mathematical model of decreasing order is constructed. Third, considering the orthogonal vector of the remaining dimension after the phase fault, the reduced-order transformation matrix expression of the general single-phase fault is obtained, which is further extended to the double-phase fault. Fourth, the harmonic current of the z1z2 subspace was tracked and controlled by the proportional integral resonant (PIR) regulator. Finally, simulation and experimental verification are performed, and the results demonstrate that the fault-tolerant control algorithm proposed in this paper can effectively reduce the torque ripple and it has good dynamic performance after an open-circuit fault.