【目的】轮毂电机空间紧凑、散热条件严苛，其内置永磁体在高温和大电枢电流冲击下极易发生不可逆退磁，严重威胁电机的可靠性与性能。针对此问题，本文设计了一种新型铁钴基组合磁极，以提高轮毂电机的抗退磁能力和综合电磁性能。【方法】首先，系统分析了不同温度和电枢电流对电机永磁体退磁特性的影响，并确定了永磁体的易退磁位置。然后，在易退磁区采用新型高矫顽力铁钴基代替传统钕铁硼，形成组合磁极，通过仿真研究了组合磁极中铁钴基与钕铁硼的不同组合比例对其电磁性能的影响，确定了铁钴基与钕铁硼的最佳组合比例。最后，对单一磁极电机和组合磁极电机的电磁性能进行对比分析。【结果】组合磁极电机在额定转矩、峰值转矩以及效率等多方面的表现更优。在110 ℃工作温度下，相较于单一磁极电机，组合磁极电机的额定转矩提升了4 N·m，峰值转矩提升了7 N·m，最高效率提高了0.4%；在160 ℃高温状态下，相较于单一磁极电机，组合磁极电机的额定转矩提升了8 N·m，转矩波动下降了0.82%，峰值转矩提升了14 N·m；在峰值工况下，组合磁极的临界退磁温度相较于单一磁极提升了15 ℃。【结论】所设计的新型铁钴基组合磁极有效提升了电机在高温及大电流工况下的抗退磁能力，并显著改善了电机的综合电磁性能，为解决轮毂电机高温易退磁问题提供了有效技术途径。

[Objective] In-wheel motors have compact space and harsh heat dissipation conditions, and the interior permanent magnets are highly susceptible to irreversible demagnetization under high temperature and large armature current surges, which seriously threatens the reliability and performance of the motors. To address this issue, this study designs a new type of FeCo-based combined magnetic pole to improve the anti-demagnetization ability and comprehensive electromagnetic performance of in-wheel motors. [Methods] Firstly, the effects of different temperatures and armature currents on the demagnetization characteristics of motor parmanent magnet were systematically analyzed, and the easily demagnetized area of permanent magnet was determined. Then, a new type of high coercivity FeCo-based material was used to replace the traditional NdFeB in the easily demagnetized area to form a combined magnetic pole. The effects of different combination ratios of FeCo-based and NdFeB in the combined magnetic pole on the electromagnetic performance were investigated through simulation, and the optimal combination ratio of FeCo-based and NdFeB was determined. Finally, the electromagnetic performance of single magnetic pole motor and combined magnetic pole motor was compared and analyzed. [Results] The motor with combined magnetic pole performed better in various aspects such as rated torque, peak torque and efficiency. At an operating temperature of 110 ℃, the rated torque of the combined magnetic pole motor increased by 4 N·m, peak torque increased by 7 N·m, and maximum efficiency increased by 0.4% compared to the single magnetic pole motor. At a high temperature of 160 ℃, the rated torque of the combined magnetic pole motor increased by 8 N·m, torque fluctuation decreased by 0.8%, and peak torque increased by 14 N·m compared to the single magnetic pole motor. At peak conditions, the critical demagnetization temperature of the combined magnetic pole was 15 ℃ higher than that of the single pole motor. [Conclusion] The designed new type of FeCo-based combined magnetic pole effectively enhances the anti-demagnetization ability of the motor under high temperature and high current operating conditions, and significantly improves the comprehensive electromagnetic performance of the motor, providing an effective technical approach to solve the problem of easy demagnetization of in-wheel motors at high temperatures.

黑龙江省自然科学基金(LH2023E084)