This paper proposes a new pole-changing memory machine (PCMM), which tactfully incorporates fractional pole-slot combination and pole-changing with memory machine. By doubling the slot number and coil span of fractional slot concentrated winding (FSCW), the machine having 9 slots 8/4 pole (9s-8/4p) combination can be changed into the one having 18 slots 8/4 pole (18s-8/4p) with 2 pitches. The electromagnetic characteristics of the two fractional-slot PCMMs (FS-PCMM), both of which can switch between 8 pole mode (8P mode) and 4 pole mode (4P mode), are analysed and compared. It demonstrates that the 18s-8/4p machine is superior to the 9s-8/4p one in aspects of unbalanced magnetic pull (UMP) and torque ripples. This study shows that the proposed 18s-8/4p FS-PCMM features satisfying variable speed characteristic so that it can be operated in wide speed range as required in electric vehicles.
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