Research On Topology Optimization And Control Strategy Of Multi-tooth Fault-toterant Flux Switching Permanent Magnet Motor

Reliability of electro-mechanical actuator system is highly demanded in more-electric aircraftrecent years. In order to improve the reliability and fault-tolerant capability of electro-mechanicalactuator based on permanent magnet machine, a six-phase fault-tolerant flux switching permanentmagnet machine with high power density and excellent fault tolerant capability is investigated in thispaper. Post-fault operation is realized by adopting compensation strategy.Optimization of topology of the fault tolerant flux switching permanent magnet machine is studiedwith the goal of sinusoidal flux linkage, high torque density and fault-tolerant capability. Sinusoidalflux and back-EMF are obtained by optimizing the machine topology in the axial direction.Furthermore, the rotor pole number and the width of space tooth of stator are investigated to improvethe electromagnetic performance of the machine. Finite element analysis verified that theMT-FTFSPM machine can achieve higher torque density and better fault-tolerant capability than theclassic fault tolerant permanent magnet machine. Meanwhile, large inductance of dq axis of theproposed fault-tolerant machine provides favorable conditions for flux-weakening operations.Flux-weakening capability of the machine is investigated theoretically.Fault-tolerant current control strategies are studied in order to maintain a smooth output torque atsingle-phase and multi-phase fault state. By controlling current of q axis and zero sequence undersynchronous rotating coordinates, torque ripple caused by open-circuit fault can be reduced andcopper loss is considered at the same time. In terms of different application conditions and thelimitation of converters, both maximum torque per ampere and maximum total torque compensationmethods are proposed. In condition of short-circuit fault, a compensation strategy based on faultdecomposition is proposed. With compensating for short-circuit current transfusion and normal phasecurrent loss respectively, complex online calculations are avoided. Experiments are taken on theprototype machine to verify the torque density, fault-tolerant capability of the machine and theproposed fault-tolerant control strategy.