Design And Analysis Of Hybrid Magnetic Materials And Few Rare Earth Permanent Magnet Motors

As one of the three key technologies of electric vehicles(EVs),its performance will directly affect the performance of EVs,the rare-earth permanent magnet brushless(RE-PMBL)motor has become the main choice of electric vehicle driving motor by virtue of its high power density,high efficiency,high reliability and other advantages.However,the long-term destructive exploitation of rare-earth strategic resources has led to the soaring price,objectively resulting in the increase in the price of motor systems,which to some extent has added uncertainties to the development of EVs.Therefore,how to reduce the consumption of rare earth permanent magnet while maintaining the excellent performance of the motor has become a new research direction in the field of permanent magnet synchronous motor.Combined with the design indexes of the driving motor,a less-rare-earth Hybrid Permanent Magnet(LRE-HPM)motor is proposed in the paper,which can reduce the consumption of permanent magnet material while maintaining the high torque output.Besides,the LRE-HPM motor has a wide speed range and a strong anti-demagnetization capability.The main contents of this paper are:Firstly,the research status quo of driving motors in EVs is summarized.Based on the non-rare-earth Permanent Magnet(NRE-PMBL)motors and less-rare-earth Permanent Magnet(LRE-HPM)motors,the structure of LRE-HPM motor is proposed in combination with the performance requirements of driving motors of electric vehicles.The operation principle of the motor is analyzed,and the main structure size of the motor is preliminarily determined.Secondly,a parameterized model of LRE-HPM motor is set up.The output torque,torque ripple,rate of salient pole and electromagnetic properties such as iron loss are chosen as the optimization goal.The motor parameters are stratified by parameter sensitivity analysis.Response surface analysis is carried out for key parameters,and Pareto optimal solution set is obtained based on Multi Objective Genetic Algorithm(MOGA)optimization.For low sensitivity parameters,single parameter optimization scanning analysis is carried out to determine the optimal structure size of the motor.Thirdly,the electromagnetic performance of LRE-HPM motor is analyzed.The conventional electromagnetic properties are researched such as magnetic field distribution,no-load Back-EMF and torque characteristics.In addition,the anti-demagnetization capability,speed regulation and cost of permanent magnet are studied.The performance before and after the optimization design are then compared and analyzed,which further verified the rationality of the motor structure and the feasibility of the design.Finally,the machining scheme of LRE-HPM motor is given,and the machining drawing is designed.At present,the machining of the principle prototype is still in progress,and the silicon steel plates of stator and rotor have been cut.After the processing of the principle prototype is completed,the subsequent experimental analysis will be carried out.