Demagnetization mechanism and local infiltration of heavy rare earth for permanent magnet synchronous motor in electric vehicles

• Published in: Dianji yu Kongzhi Xuebao = Electric Machines and Control Vol. 28; no. 3; p. 75
• Main Authors: Xie, Ying, Sun, Cunjun, Cai, Wei, Ren, Shaoqing, Jiang, Jianing
• Format: Journal Article
• Language: Chinese; English
• Published: Harbin Harbin University of Science and Technology 01.01.2024
• Subjects: Coercivity; Demagnetization; Design factors; Dysprosium; Electric vehicles; High temperature; Infiltration; Permanent magnets; Rare earth elements; Synchronous motors; Triangles; Weight reduction
• ISSN: 1007-449X
• DOI: 10.15938/j.emc.2024.03.008

Due to the design requirements of permanent magnet synchronous motor（PMSM） for electric vehicles with high power density, the magnet is more susceptible to electromagnetic and high temperature influence, resulting in demagnetization. A large number of precious rare earth elements such as dysprosium and terbium are added in the preparation of the magnet to solve the problem, but the price of magnet is higher using this method. The influence of temperature, armature current and flux weakening angle on the demagnetization characteristics of the magnet were studied for the demagnetization problem of a triangle-pole structure PMSM, and then the position and diffusion law of the demagnetization of the magnet were determined. According to the basement, by changing the grade of the motor magnet material to a lower grade and putting forward a reasonable design scheme of selective heavy rare earth infiltration, the purpose of reducing the amount of heavy rare earth elements without losing the motor performance was realized. Finally, based on the principle of magnetic demagnetization, a method was proposed to calculate the maximum coercivity increase factor in the design scheme of local infiltration of heavy rare earth, which can provide reference for the research and design of magnet weight reduction rare earth for electric vehicles PMSM.