Abstract The Maxwell stress tensor (MST) method is commonly used to accurately compute the global efforts, such as electromagnetic torque ripple and unbalanced electromagnetic forces in electrical machines. The MST has been extended to the estimation of local magnetic surface force for the vibroacoustic design of electrical machines under electromagnetic excitation. In particular, one common air-gap surface force (AGSF) method based on MST is to compute magnetic surface forces on a cylindrical shell in the air gap. However, the AGSF distribution depends on the radius of the cylindrical shell. The main contribution of this study is to demonstrate an analytic transfer law of the AGSF between the air gap and the stator bore radius. It allows us to quantify the error between the magnetic surface force calculated in the middle of the air gap and the magnetic force computed on the stator teeth. This study shows the strong influence of the transfer law on the computed tangential surface force distribution through numerical applications with induction and synchronous electrical machines. Finally, the surface force density at stator bore radius is more accurately estimated when applying the new transfer law on the AGSF.

中文翻译：

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气隙表面力的分析研究——在电机中的应用

摘要 麦克斯韦应力张量 (MST) 方法通常用于精确计算全局作用力，例如电机中的电磁转矩脉动和不平衡电磁力。MST 已扩展到用于电磁激​​励下电机振动声设计的局部磁表面力的估计。特别是，一种基于 MST 的常见气隙表面力 (AGSF) 方法是计算气隙中圆柱壳上的磁表面力。然而，AGSF 分布取决于圆柱壳的半径。本研究的主要贡献是证明了气隙和定子孔半径之间 AGSF 的解析传递定律。它使我们能够量化在气隙中间计算的磁表面力与在定子齿上计算的磁力之间的误差。本研究通过感应电机和同步电机的数值应用显示了传递定律对计算出的切向表面力分布的强烈影响。最后，在 AGSF 上应用新的传递定律时，可以更准确地估计定子孔半径处的表面力密度。