Fault tolerant machine drives are being favored by safety-critical applications. However, the machine needs to be carefully designed since it is required to achieve high performance in healthy condition as well as good fault tolerance for various faults. Meanwhile, the design should also satisfy electric, thermal, and mechanical constraints. This paper has performed an optimization for a triple redundant nine phase fault tolerant permanent magnet assisted synchronous reluctance machine (PMA SynRM). Various design tools have been facilitated to assess the electromagnetic, thermal, and mechanical performances and guarantee that the design meets all the limits in both the healthy and faulty operations. A prototype has been built according to the optimization, the test results verify that the design achieves high performance and excellent fault tolerant and satisfies various design constraints. INDEX TERMS Fault tolerant, PMA SynRM, turn fault, design optimization, thermal design.

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Stator turn fault is the most serious failure in the electrical machine drive which requires immediate detection techniques. Under such a turn fault, the fundamental change is that the high frequency (HF) impedance of the fault phase is significantly reduced due to the flux nullifying effect of the fault turns. Thus, this paper proposes a novel turn fault detection technique by using the equivalent HF impedance. It is derived by the HF voltage and current signals which are obtained by processing the phase voltages and currents with a bandpass filter. The effectiveness of the proposed is verified by extensive simulation and experimental tests on both surface mounted and interior PM machines. It is demonstrated that the performance of the proposed detection method is superior than the conventional HF current ripple based method. The investigation also confirms that the fault can be detected at an early stage by the proposed method.INDEX TERMS Turn fault detection, high frequency, current harmonic, voltage harmonic, impedance, bandpass filter.

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