【目的】针对屏蔽式永磁同步电机(CPMSM)普遍存在齿槽转矩大、电机效率偏低以及转矩脉动大等问题，本文旨在分析非对称永磁体结构对CPMSM性能的影响。【方法】本文以工程常用弧型永磁体为基础，以单块永磁体几何中心线为基准，通过偏移永磁体内、外径圆心的方式实现永磁体单侧偏心结构设计，提出三种非对称永磁体结构。系统对比分析了不同永磁体结构的CPMSM在空载与负载工况下的气隙磁密、感应电动势、屏蔽套单侧磁拉力、永磁体退磁系数、电机损耗及运行效率等关键电机性能。【结果】结果表明，三种非对称永磁体结构的性能变化趋势基本一致:随着永磁体中心偏移量增大，气隙磁密幅值降低；齿槽转矩幅值与屏蔽套损耗随之同步减小，电机效率得到提升。在不考虑加工制造难度与成本的条件下，左侧非对称结构为最优方案，该结构电机效率与功率因数最高，输出转矩降幅最小，转矩脉动抑制效果最为显著。此外，非对称永磁体所引发的不平衡磁拉力对电机整体性能的影响可忽略。相较于传统定子齿开槽优化方案，所提方法在抑制齿槽转矩的同时可维持良好的电磁性能，具备显著优势。【结论】本文所提非对称永磁体结构在削弱齿槽转矩、抑制转矩脉动以及改善电机综合性能方面效果显著。该结构虽会带来一定程度的磁路不平衡，但不会改变电机整体磁路分布特征，电机依旧可以保持优良的电磁性能。本研究可为CPMSM的优化设计提供一定参考。

[Objective] To address the issue of large cogging torque, low motor efficiency and high torque ripple commonly found in canned permanent magnet synchronous motor (CPMSM), this paper aims to analyze the influence of asymmetric permanent magnet structure on the performance of CPMSM. [Methods] Based on the arc-shaped permanent magnet commonly used in engineering, this paper adopted the geometric centerline of a single permanent magnet as the reference. The unilateral eccentric design of the permanent magnet was realized by offsetting the centers of its inner and outer diameters, and three asymmetric permanent magnet structures were proposed. The key motor performances of CPMSM with different permanent magnet structures, including air-gap flux density, induced electromotive force, unilateral magnetic pull of the can sleeve, demagnetization coefficient of permanent magnets, motor losses and operating efficiency, were systematically compared and analyzed under no-load and load conditions. [Results] The results showed that the three asymmetric permanent magnet structures shared basically the same performance variation trend. As the offset of the permanent magnet center increased, the amplitude of air-gap flux density decreased. The amplitudes of cogging torque and can loss decreased accordingly, and the motor efficiency was improved. Without taking manufacturing difficulty and cost into account, the left-side asymmetric structure was the optimal scheme. The motor with this structure obtained the highest efficiency and power factor, the smallest drop in output torque, and the most prominent suppression effect on torque ripple. In addition, the unbalanced magnetic pull caused by the asymmetric permanent magnet exerted a negligible effect on the overall performance of the motor. Compared with the conventional optimization scheme of stator-tooth slotting, the proposed method suppressed cogging torque while maintaining favorable electromagnetic performance, and exhibited remarkable advantages. [Conclusion] The asymmetric permanent magnet structure proposed in this paper achieve remarkable performance in weakening cogging torque, suppressing torque ripple and improving the comprehensive performance of CPMSM. Although this structure brings a certain degree of magnetic-circuit unbalance, it does not alter the overall magnetic-circuit distribution characteristics of the motor, and the motor still maintain excellent electromagnetic performance. This study provides references for the optimal design of CPMSM.

国家自然科学基金(62473061);辽宁省博士科研启动基金(2025-BS-0809)