Cancellation of Torque Ripples With FOC Strategy Under Two-Phase Failures of the Five-Phase PM Motor

This paper investigates torque ripples cancellation of a five-phase (5Ph) permanent magnet (PM) motor under open fault of two phases, where failure phases are either adjacent or nonadjacent. In recent works, torque ripples cancellation is performed at a stationary frame and postfault current solutions for constant output torque are complicated. To implement field-oriented control (FOC) and carrier-based pulse width modulation, reduced-order Clarke and Park transformations are proposed. With the coordinate transformation, a 5Ph motor model under unbalanced conditions has been decoupled. Along with this, the fundamental torque at the d-q frame also remains the same as the healthy case. However, third harmonic of winding density distribution results in torque ripples. To reduce dependence on mathematical model of torque ripples, sliding mode control is employed to calculate q -axis current reference while keeping constant the rotor speed. Decoupled models corresponding to two types of faults, which are adjacent and nonadjacent open fault, are confirmed by finite element analysis, and effectiveness of proposed torque ripples cancellation method is verified on the 5Ph drive in the laboratory.