【目的】针对稀土材料稀缺昂贵导致新能源汽车驱动电机成本高昂的问题,本研究旨在采用低成本的铁氧体材料替代部分钕铁硼永磁体以降低制造成本。【方法】以电动大巴车U型内置式驱动电机为研究对象,设计3种钕铁硼与铁氧体混合的永磁转子结构,采用有限元方法分析不同永磁体排布方式对电机输出转矩、磁阻转矩以及气隙磁密畸变的影响,选出磁阻转矩、输出转矩优势明显的非对称磁极排列结构。在永磁体用量不变的前提下,对永磁体角度、距离、磁桥间距进行多参数优化。最后,基于一台现有的110 kW钕铁硼样机测试电机反电动势与转矩-电流特性,并将实测数据与仿真数据对比分析。【结果】相较于其余排布方式,单极不对称两极对称的磁极排列结构可实现更高的磁阻转矩与输出转矩,经多参数优化后,电机输出转矩提升4.4%,磁阻转矩提升2.5%。样机实测的反电动势、转矩-电流特性与有限元仿真数值高度吻合。【结论】该方案通过部分替代钕铁硼永磁体,在有效降低电机制造成本的同时,借助对单极不对称及两极对称等多种磁极排列结构的多参数优化,实现了在不增加永磁材料用量前提下的转矩性能提升。此外,通过现有样机的试验测试,验证了本文所采用的有限元仿真计算方法的正确性与准确性。

[Objective] To address the problem of high costs in manufacturing new energy vehicle drive motors caused by the scarcity and high price of rare earth materials, this study aims to reduce manufacturing costs by using low-cost ferrite materials to replace some of the neodymium iron boron permanent magnets. [Methods] Taking the U-shaped interior permanent magnet drive motor of an electric bus as the research object, three types of hybrid permanent magnet rotor structures combining neodymium iron boron and ferrite were designed. The finite element method was used to analyze the influence of different permanent magnet arrangements on the motor’s output torque, reluctance torque performance, and air-gap flux density distortion, and an asymmetric magnetic pole arrangement structure with obvious advantages in reluctance torque and output torque was selected. On the premise of unchanged permanent magnet usage, multi-parameter optimization was performed on the permanent magnet angle, distance, and magnetic bridge spacing. Finally, used an existing 110 kW neodymium iron boron prototype, the motor’s back electromotive force and torque-current characteristics were tested, and the measured data were compared with the simulation data. [Results] Compared with other arrangements, the single-pole asymmetric and two-pole symmetric magnetic pole arrangement structure achieves higher reluctance torque and output torque. After multi-parameter optimization, the motor’s output torque improved by 4.4% and the reluctance torque increased by 2.5%. The experimentally measured back-electromotive force and torque-current characteristics of the prototype shows a high degree of agreement with the finite element simulation values. [Conclusion] This solution partially replaces neodymium iron boron permanent magnets, which effectively reduces the manufacturing cost of the motor. At the same time, through multi-parameter optimization of various magnetic pole arrangement structures, such as single-pole asymmetric and two-pole symmetric structures, it achieves improved torque performance without increasing the amount of permanent magnet material used. Furthermore, experimental tests on an existing prototype verify the correctness and accuracy of the finite element simulation calculation method used in this paper.

辽宁省科技厅联合基金项目面上资助计划项目（2023-MSLH-247)