Research On Permanent Magnet Synchronous Motor With V-shaped Magnet Structure For Electric Vehicles

In recent years,with the rapid development of the world economy,the atmospheric environment has also deteriorated.It is the consensus of the world to use new energy vehicles such as electric vehicles instead of fuel vehicles to control air pollution.As the core part of the electric vehicle,the motor and its driving system are the key to determine the overall performance and driving experience of the electric vehicle.Therefore,the research of electric motor and its driving system for electric vehicles has become an important topic in the field of motor research.Permanent magnet synchronous motor with V-shaped rotor magnet structure can make full use of its reluctance torque and has higher torque density and power density.In this paper,permanent magnet synchronous motor(PMSM)with V-shaped rotor magnet structure for electric vehicle is studied,and the performance of the motor is further improved.The main contents of this paper are as follows:1.The mathematical model of permanent magnet synchronous motor with V-shaped rotor magnet structure is studied,and the common numerical calculation methods of quadrature-axis and direct-axis inductance parameters are analyzed and compared.Using finite element method the based on frozen permeability and fully considering the saturation of magnetic circuit and the coupling of quadrature-axis and direct-axis magnetic circuits,the quadrature-axis and direct-axis inductance parameters of permanent magnet synchronous motor with V-shaped rotor magnet structure under different load operating conditions are calculated,and the interpolation algorithm based on thin-plate spline function is used to fit the parameter data,which lays the foundation of data for the simulation and optimization of the motor drive system.2.For permanent magnet synchronous motor with V-shaped rotor magnet structure used in electric vehicles,an improved rotor structure with small magnetic isolation gaps is proposed to optimize the sinusoidality of its back EMF waveform.The effects of the design variables on the EMF amplitude,the sinusoidal waveform and the cogging torque of the rotor structure are studied,such as the width,thickness,position and width of small magnetic isolation gaps,the angle between the V-shaped permanent magnet.3.A multi-objective and global parameter optimization design method for V-shaped permanent magnet rotor structure based on genetic algorithm and response surface method is proposed.The optimization design is carried out to optimize the sinusoidal waveform and reduce the torque ripple while increasing the opposite electromotive force.4.The design of shift mechanism on the permanent magnet synchronous motor with V-shaped rotor magnet structure based on winding switching solves the contradiction between low-speed and high-speed operation of electric vehicle drive motor,and effectively avoids the risk of increasing copper loss in weak magnetic region and irreversible demagnetization of permanent magnet.On this basis,a joint simulation model of PMSM with V-shaped rotor magnet structure and its drive system using Simpler and Maxwell is established to verify the performance of the whole electric vehicle drive system.5.Design and test of prototype.A prototype of permanent magnet synchronous motor with V-shaped rotor magnet structure for electric vehicle is trial-manufactured.The no-load test and load test of the prototype are carried out.The experimental data are compared with the results of finite element analysis to verify the performance of the prototype.6.Summary and outlook.A comprehensive summary and conclusions of the subject are made,and some suggestions for further research work are put forward.