基于磁场调制原理的齿槽转矩研究

Investigation of Cogging Torque Based on Magnetic Field Modulation Principle

永磁电机的齿槽转矩会引起电机转矩波动,降低电机控制精度。如何降低齿槽转矩一直是永磁电机领域研究的热点之一。传统齿槽转矩解析方法通常基于能量法。该文将能量法和磁场调制理论相结合,提出一种新的永磁电机齿槽转矩分析方法,对齿槽转矩的产生机理进行解释,并对齿槽转矩表达式进行推导,证明齿槽转矩是若干调制磁场相互作用的结果。通过对齿槽转矩分量表达式进行分析得出,要产生任意齿槽转矩分量,谐波永磁磁场和谐波气隙磁导需要满足的周期约束关系。之后对整数槽绕组电机和分数槽绕组电机进行有限元仿真,研究不同极槽配合下的电机齿槽转矩,以及气隙各次谐波磁场幅值随转子转动的变化规律,并对理论推导进行了验证。该文介绍的齿槽转矩分析方法为抑制永磁电机的齿槽转矩提供了设计思路。

The cogging torque of permanent-magnet machines will cause the torque ripple and reduce the accuracy of motor control.How to reduce the cogging torque has been one of the research hotspots in the field of permanent-magnet machines.The deduction process of traditional analytical method of cogging torque is commonly based on energy method.In this paper,a new cogging torque analysis method for permanent magnet machine is proposed by combining energy method with magnetic field modulation theory.The mechanism of cogging torque is explained,and the expression of cogging torque is deduced.It is proved that cogging torque is the result of the interaction of several modulated magnetic fields.Based on the analysis of the expression of the cogging torque component,the period constraints of the harmonic permanent magnetic field and the harmonic air-gap permeance are obtained to generate each cogging torque component.The integer-slot winding machine and the fractional-slot winding machine are simulated by finite element method.The cogging torques of machines with different pole/slot combinations are studied.The variations of the amplitudes of the harmonic magnetic fields in the air gap with the rotation of the rotor are studied,verifying the theoretical derivation.Finally,based on the analysis method of cogging torque in this paper,the design method of the machine is provided to suppress the cogging torque.