Electromagnetic Design And Loss Analysis Of High-power And High-speed Permanent Magnet Synchronous Motors

The volume of high-speed permanent magnet motor is far smaller than that of medium-low speed motor with the same power,and the power density is high.In recent years,the high-speed permanent magnet motor has been widely developed and is widely favored in centrifugal compressors,new energy vehicles,aerospace,medical equipment and other fields.However,the research of high-speed permanent magnet motor mainly focuses on small and medium power,and its design is different from that of medium and low speed motor.In this paper,the design difficulties of highspeed permanent magnet synchronous motor are discussed and analyzed.Firstly,according to the design indexes,the stator and rotor design of the high-speed permanent magnet synchronous motor is completed,including the selection of core materials,stator structure design,stator inner diameter and core length.Permanent magnet material selection,rotor permanent magnet arrangement,etc.Furthermore,the finite element software is used to simulate and verify the rationality of the theoretical analysis.With reluctance torque and air-gap flux density as optimization objectives,the combined rotor of magnetic pole was optimized on the basis of the original motor,i.e.,the soft magnet Halbach motor was added,and the optimal position and size of the soft magnet in the original tangential magnetizing permanent magnet were determined.The performance of nonuniform and unequal thickness Halbach motor(original motor),traditional Halbach motor and soft magnetic Halbach motor is compared.The results show that soft magnetic Halbach motor has larger air gap magnetic density,maximum reluctance torque and better performance.The risk of rotor damage can be avoided by stress checking of rotor part of high speed permanent magnet motor.Based on the rotor strength analysis theory of Workbench,this paper compared and analyzed the stress of the permanent magnet and sheath when carbon fiber,titanium alloy and stainless steel were used as sheath,and selected an appropriate interference value for them.A suitable core loss model is selected to analyze the magnetization characteristics of different parts of the stator and the analytical method is combined with the finite element method to calculate the stator iron loss.The formula method is used to calculate the copper consumption of the motor analytically.The eddy current losses of the permanent magnet and the three kinds of sheathing are calculated by using the finite element software,and then the carbon fiber material is selected as the protection sleeve.