Research On The Electromagnetic Field And Stucture Optimization Of Permanent Magnet Synchronous Motor

With the constant development of society,people are in possession of an increasingly strong awareness of energy conservation and environmental protection.As the core component of new energy vehicles,motor has been paid more and more attention nowadays.Permanent magnet synchronous motor(PMSM)has the characteristics of simple structure,small volume,light weight and high efficiency.Compared with an induction motor,PMSM has more outstanding performances in high efficiency and energy saving,so it has been more widely accepted and applied in the machinery manufacturing industry.As the core material of permanent magnet synchronous motor,rare earth resources in China is extremely rich,thus our country can take advantage of more R&D on the rare earth permanent magnet motor.In this paper,the research work is concentrated on a 2.8KW permanent magnet synchronous motor for low speed electric vehicle as follows.Firstly,the structure as well as the mathematical model of the permanent magnet synchronous motor was introduced.Subsequently,the relevant theory and calculation methods of the electromagnetic field of the motor was discussed.Then the finite element simulation model of the motor is established by adopting the electromagnetic analysis software Ansoft.Secondly,the finite element software Ansoft is applied to simulate and analyze the electromagnetic field of this permanent magnet synchronous motor in both its no-load and load with respected to the magnetic fields.The distributions of magnetic flux and magnetic flux density in the whole motor boundary are obtained with and without magnetic field.At the same time,several key performance parameters of the motor were calculated,including the magnetic flux density and its harmonic content,induced electromotive force and its harmonic content,no-load leakage coefficient,cogging torque and its load torque.Thirdly,by using parametric analysis function of Ansoft software,the influences of the change of every dimension parameter on the motor performance when changing the four key dimensions of the motor(motor slot width,air gap length,length of permanent magnet magnetization direction,and permanent magnet width)were analyzed,which can provide reference for the optimization of the motor structure.Finally,Taguchi optimization method is introduced to optimize the structure of the motor so as to increase the average torque as well as to reduce the back-EMF harmonic content and the cogging torque.Through the finite element simulation experiment,the optimal combination of the structure size were obtained.The optimization results show that the average torque of the motor is increased by 7.54%,the cogging torque is reduced by 40.7%,and the harmonic content of the no-load back electromotive force is reduced by 17.4%.Through the indirect experiment,the test data and the simulation data of the motor were analyzed and then calculate the deviation value between them.As its value is within the allowed error range,the reliability of the simulation and optimization is thus proved.