The calculation accuracy of unbalanced magnetic forces (UMF) is very important to the design of rotor length, because it will effect the shaft deflection. But in some permanent magnet synchronous motors (PMSMs) with fractional slot concentrated windings (FSCW), the UMF caused by asymmetrical statortopology structure is not considered in the existing deflection calculation, which is very fatal for the operational reliability, especially for the PMSMs with the large length-diameter ratio, such as submersible PMSMs. Therefore, the part of UMF in the asymmetrical stator topology structure PMSMs caused by the choice of pole-slot combinations is analysized in this paper, and a more accurate rotor deflection calculation method is also proposed.

中文翻译：

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带有不等分槽集中绕组的永磁同步电动机中不平衡磁力对轴挠度的影响

不平衡磁力（UMF）的计算精度对于转子长度的设计非常重要，因为它会影响轴的挠度。但是在某些带有分数槽集中绕组（FSCW）的永磁同步电动机（PMSM）中，在现有的挠度计算中并未考虑由不对称定子拓扑结构引起的UMF，这对于运行可靠性非常致命，特别是对于具有以下特征的PMSM：长径比大，例如潜水式PMSM。因此，本文分析了由于极槽组合的选择而引起的非对称定子拓扑结构PMSMs中的UMF部分，并提出了一种更精确的转子挠度计算方法。