Purpose

This paper aims to propose a method to evaluate the information obtained on harmonics calculations and to estimate the precision of results using finite element method for an innovative motor topology in which some well-known meshing rules are difficult to apply.

Design/methodology/approach

The same magnetostatic problem is solved with several mesh sizes using both scalar and vector potentials magnetics formulations on a complex topology, an axial claw pole motor (ACPM). The proposed method lies in a comparison between the two weak formulations to determine what information is obtained on harmonics calculations and to estimate its precision. Moreover, an original mesh method is applied in the air gap to improve the numerical results.

Findings

The precision on harmonics calculations using finite element method on an ACPM is estimated. For the proposed motor and mesh, only the mean value (even with large mesh) and the first harmonic (with fine mesh) of torque are calculated with a good accuracy. This results confirm that the non-respect of the meshing rules have a strong impact on the results and that scalar and vector potentials magnetics formulations do not give exactly the same results. Before using torque harmonics values in vibration calculations, a finite element model has to be validated by using both fomulations.

Research limitations/implications

This method is time-consuming and only applied on an ACPM in this work.

Originality/value

The axial claw pole motor, for which the classic meshing rules cannot be applied, is a complex topology very under-studied. To improve the calculation of space harmonics, the authors proposed to split the airgap into four parts. Then in the two central parts, the meshing step of the structured mesh is equal to the rotating step.

中文翻译：

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轴向爪极电动机：使用有限元方法估算谐波转矩

目的

本文旨在提出一种方法，用于对谐波计算中获得的信息进行评估，并使用有限元方法估算创新电机拓扑的结果，该方法难以应用某些众所周知的啮合规则。

设计/方法/方法

使用标量和矢量势磁公式在复杂的拓扑结构（轴向爪极电动机（ACPM））上使用数种网格尺寸解决了相同的静磁问题。所提出的方法在于两种弱公式之间的比较，以确定在谐波计算中获得哪些信息并估计其精度。此外，在气隙中采用了原始的网格方法来改善数值结果。

发现

估计在ACPM上使用有限元方法计算谐波的精度。对于所提出的电动机和啮合，仅以良好的精度计算了扭矩的平均值（即使是大啮合）和一次谐波（精细啮合）。该结果证实了不遵守啮合规则对结果有很大的影响，并且标量和矢量势的磁学公式不能给出完全相同的结果。在振动计算中使用转矩谐波值之前，必须同时使用两个公式来验证有限元模型。

研究局限/意义

此方法很耗时，并且仅在此工作中应用于ACPM。

创意/价值

不能应用经典啮合规则的轴向爪极电动机是一种复杂的拓扑结构，但研究不足。为了改善空间谐波的计算，作者建议将气隙分成四个部分。然后，在两个中心部分中，结构化网格的啮合步骤等于旋转步骤。