转子温度空间分布差异诱发永磁电机局部失磁特性研究

Research on Local Demagnetization Characteristics of Permanent Magnet Motor Induced by Spatial Distribution Difference of Rotor Temperature

永磁材料磁特性受工作温度影响较大,高工作温度下存在的不可逆失磁现象是永磁电机高可靠性设计的主要瓶颈。针对内置式磁路结构的高功率密度永磁电机用钕铁硼永磁材料的不可逆失磁问题,基于电机全域空间损耗、温度分布的差异,该文提出一种永磁体局部失磁分析模型与特性计算方法。通过磁体虚拟分块法建立基于温度、退磁率等变量的永磁材料磁特性分析模型,利用电磁场和温度场双向耦合的三维多物理场计算方法,得到电机转子永磁体损耗、温度和局部失磁的空间分布特性。最后,通过对一台115 kW、8极永磁电机样机转子永磁体温度和转子表面磁场的实验测试,验证了分析模型与计算方法的准确性,为永磁电机局部失磁问题研究及精细化防失磁设计提供依据。

The magnetic properties of permanent magnets are greatly affected by their operating temperature.Irreversible demagnetization at high operating temperature is the main bottleneck in high reliability design of permanent magnet motors.In order to solve the irreversible demagnetization problem of NdFeB permanent magnet for high power density permanent magnet motor with interior magnetic circuit structure,based on the difference of space loss and temperature distribution in the whole area of the motor,an analysis model and characteristic calculation method for local demagnetization of permanent magnet are proposed in this paper.The magnetic characteristic analysis model of permanent magnet material based on temperature,demagnetization and other variables is established by virtual block method of magnet.The spatial distribution characteristics of permanent magnet loss,temperature and local demagnetization of motor rotor are obtained by using the calculation method of bidirectional coupling of three-dimensional electromagnetic field and temperature field.Finally,the accuracy of analysis model and calculation method is verified by the test of permanent magnet temperature and magnetic field on rotor surface of a 115kW,8-pole permanent magnet motor prototype,which provides basis for the research of permanent magnet motor local demagnetization problem and fine demagnetization protection design.