Study on method of eddy-current-loss suppression and power-factor enhancement of integrated magnetic-field-modulated machine

集成式磁场调制电机涡流损耗抑制与功率因数提升方法研究

¹ Beijing Institute of Automatic Control Equipment, Beijing 100074, China
² School of Automation, Northwestern Polytechnical University, Xi'an 710072, China

Received: 12 February 2025

Abstract

Integrated magnetic-field-modulated machine is a single-air-gap magnetic-field-modulated machine, which is highly integrated by using the magnetic gear and high-speed permanent-magnet machine. It has the advantages of compact structure, high torque density, high reliability, which has potential application prospects in aerospace area. However, this kind of machine uses the multiple modulation harmonics with small amplitude for energy conversation, resulting in the large harmonic loss and low power factor. To solve the above mentioned problems, the eddy current loss suppression and power factor enhancement methods of the integrated magnetic-field-modulated machine are studied. Firstly, the modulated magnetic-field composition of machine is analyzed to determine the contribution of permanent-magnet modulated harmonics and armature modulated harmonics to electromagnetic torque. Secondly, the loss production mechanism is studied. As the eddy current loss of permanent magnet is the main loss, the influence of the permanent magnet segmentation on the eddy current loss is studied. In order to optimize the air gap performance, two improved configurations of the modulated rotor are proposed. Thirdly, the expression of the power factor under different control strategy is deduced. The power factor enhancement method is studied in aspect of the control strategy and the machine design. Finally, a prototype of the integrated magnetic-field-modulated machine is manufactured. The test bench is built up to carry out the experiment. The experimental results verify the correctness and feasibility of the theoretical analysis. The results show that the circumferential segmentation scheme of the permanent magnet can reduce the eddy current loss by at least 75%. The sinusoidal-surface configuration of the modulated rotor can reduce the eddy current loss to 73% of the conventional configuration. By adjusting the input phase angle of the machine, the power factor can be increased by 25%, the eddy current loss can be reduced by 50%, and the efficiency can be increased by 10% without the sacrificing torque.

摘要

集成式磁场调制电机是一种由磁性齿轮与高速永磁电机高度集成的单气隙磁场调制原理电机, 具有结构紧凑、转矩密度高、可靠性高等优点, 在航天领域具有潜在应用前景。然而, 该类电机利用幅值小、次数多的调制谐波进行能量转换, 因此存在谐波损耗大、功率因数低的问题。针对以上问题, 对集成式磁场调制电机涡流损耗抑制与功率因数提升方法展开研究。对电机调制谐波磁场组成进行分析, 确定永磁调制谐波与定子电枢调制谐波对电磁转矩的贡献。对电机损耗产生机理进行研究, 确定永磁体涡流损耗为主要损耗, 研究永磁体分块对其影响规律; 为优化气隙磁导波形, 提出2种改进的调制转子构型。推导不同控制方式下电机功率因数表达式, 从电机控制策略和本体设计两方面出发, 探讨功率因数提升方法。研制样机, 搭建实验平台并进行实验测试, 验证理论分析的正确性与可行性。结果表明: 永磁体周向分块方案可使永磁体涡流损耗降低75%以上; 表面正弦的调制转子构型可使永磁体涡流损耗减小为改进前的73%;通过调节电机输入相角, 可在不牺牲转矩的前提下, 使功率因数提升25%, 永磁体涡流损耗降低50%, 效率提升10%。