In this article, the relationship between slot-pole combination and electromagnetic performance of a partitioned-stator field-excitation (PS-FE) brushless machine is analyzed by air-gap field modulation principle (AFMP). Firstly, the air-gap field modulation process of two PS-FE machines is investigated with the inner stator pole number Ni/rotor pole number Nr/outer stator slot number No of 8/18/42 and 12/10/12 respectively, and verified by finite element analysis (FEA) and experiments. Then, a general combination (Rule-I), a deprecated combination (Rule-II) and a compensatory combination (Rule-III) are defined to guide the slot-pole selection. It is found that if Nr is an integer multiple of Ni/2 (i.e. the inner stator pole pairs number pi), the air-gap flux-densities will contain only the integer multiple harmonics of pi, resulting in an asymmetric flux-linkage and a back-electromotive force (back-EMF) in the armature windings. Although symmetric flux-linkage and back-EMF can be performed by Rule-III, a higher torque ripple and a higher DC-winding-induced flux-linkage exist in the PS-FE machines. Hence, Rule-IV and the saturated inner stator effect are discussed to pursue a lower DC-winding-induced flux-linkage, thereby a lower induced voltage under both open-circuit and on-load. Finally, rules are listed and the important findings are summarized.

中文翻译：

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气隙场调制原理分区定子励磁无刷电机槽极组合与性能关系


本文利用气隙场调制原理（AFMP）分析了分区定子场励磁（PS-FE）无刷电机的槽极组合与电磁性能之间的关系。首先，研究内定子极数Ni/转子极数Nr/外定子槽数No分别为8/18/42和12/10/12的两台PS-FE电机的气隙磁场调制过程，并通过有限元分析（FEA）和实验验证。然后，定义一般组合（规则-I）、不推荐组合（规则-II）和补偿组合（规则-III）来指导槽极选择。研究发现，如果Nr为Ni/2的整数倍（即内定子极对数pi），则气隙磁通密度将仅包含pi的整数倍谐波，导致磁链不对称，电枢绕组中的反电动势（反电动势）。尽管对称磁链和反电动势可以通过规则 III 执行，但 PS-FE 电机中存在更高的扭矩纹波和更高的直流绕组感应磁链。因此，讨论规则 IV 和饱和内定子效应，以追求较低的直流绕组感应磁链，从而在开路和负载下实现较低的感应电压。最后，列出了规则并总结了重要的发现。