Optimal pole width ratio for high force density linear switched reluctance motors

Abstract

The double salient structure significantly reduces the forces in a linear switched reluctance motor (LSRM). The structure is then optimized for high force densities. The pole width is the key parameter in the double salient structure with this paper focusing on the optimal pole width ratio for a high force density LSRM using qualitative and quantitative analyses and experimental measurements. The qualitative analysis based on a linear flux linkage model shows a maximum average force for various translator and stator pole widths. Then, a finite element analysis (FEA) based parametric modeling method is used to validate the results and to calculate the optimal pole width range. Force measurements then agree well with the FEA results. They both show that the optimal stator pole width ratio is 0.4 to 0.45 and the optimal translator pole width ratio is 0.45 to 0.5 for a high force density in the LSRM. The optimal width ratio does not change with the air gap or slot depth. 摘要 双凸极作为直线开关磁阻电机 (LSRM) 的特征结构对于电机的出力性能有着较大的影响。由于极宽是双凸极结构的关键尺寸, 因此该文从理论定性分析、有限元定量分析和实验测量3个方面探究了提升LSRM力密度的最佳定动子极宽比。利用磁链线性模型定性地分析了定动子极宽如何影响电机平均输出力, 从机理上揭示了定子和动子极宽分别存在使得平均输出力最大的极值点。利用参数化建模方法建立了有限元分析模型, 定量地验证了理论分析的推断并给出了最大平均输出力所对应的最佳定动子极宽比范围。通过实验测量了不同定动子极宽的力曲线, 实验测量结果和有限元计算结果相一致, 从而验证了有限元分析的准确性。有限元分析和实验结果表明：对于提升LSRM力密度的最佳定子极宽比范围为0.4~0.45, 最佳动子极宽比范围为0.45~0.5, 且最佳定动子极宽比范围基本不受气隙、槽深的影响。