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A fault-tolerant permanent-magnet vernier (FT-PMV) machine incorporates the merits of high fault-tolerant capability and high torque density. In this paper, a remedial phase-angle control (RPAC) strategy is proposed for a five-phase FT-PMV machine with short-circuit fault. Firstly, the proposed strategy can reduce the amount of unknown quantities by structuring the phase-angles of the normal phases. It can simplify the calculation of the remedial currents. Then, in order to obtain the desired torque, only the amplitudes of the remedial currents need to be calculated. Based on the principle of instantaneous electrical input power and mechanical output power balance condition, the real components are used to maintain the torque capability, while the reactive components are limited zero to minimize the torque ripple. Both simulations and experiments are presented to verify the proposed RPAC strategy.

A fault-tolerant permanent-magnet vernier (FT-PMV) machine incorporates the merits of high fault-tolerant capability and high torque density. In this paper, a new remedial control is proposed for a five-phase FT-PMV machine with short-circuit fault of stator windings. Based on the principle of copper loss minimization, the aims of the proposed control strategy are to keep magnetic motive force (MMF) unchanged and minimize torque ripple. The proposed remedial control strategy contains two parts. Firstly, the remedial currents of the healthy phases are used to compensate for the ripple of MMF caused by the short-circuit current. Secondly, an open-circuit fault-tolerant control strategy is used to compensate for the lack of normal torque in the fault phase. Finally, the vector sum of two parts is adopted to derive the remedial currents. The final expression of the proposed remedial current is simpler than that than these previous methods. In addition, the proposed remedial currents are sinusoidal, which can reduce the reactive component in instantaneous power produced by pulsating torque and iron loss of a sine back-EMF machine. A FT-PMV prototype is built. The simulations and the experiments verify the effectiveness of the proposed strategy.