Design And Driving Simulation Analysis Of Permanent Magnet Synchronous Motor For Electric Vehicle

Permanent magnet synchronous motor(PMSM)is widely used in vehicle drive motor because of its high power density,strong overload capacity,high reliability and high torque density.Due to the complex and changeable road conditions,vehicles often need short-term acceleration and climbing in the process of driving,so the torque performance of the drive motor is required to be high.In the process of motor design,when the motor torque performance is improved,the heat production of the motor will also increase,resulting in excessive temperature in the motor.In this paper,the electromagnetic design and temperature prediction of a permanent magnet synchronous motor for electric vehicle are presented.Firstly,the structure of stator and rotor,air gap and permanent magnet parameters of PMSM for electric bus are designed based on the dynamic parameters and operation characteristics of PMSM for electric bus.According to the magnetic circuit method,the electromagnetic design of the motor is carried out,and the transient magnetic field of the designed motor is analyzed by using the finite element software.Secondly,the basic concepts of equivalent heat path method are introduced,including the three forms of heat transfer,the concept and calculation formula of thermal resistance,heat capacity and heat source.According to the characteristics of the internal structure of the motor,the equivalent model of the rotor with complex structure is established.The equivalent thermal resistance of each part is calculated by using different kinds of heat transfer models.According to the structure distribution and heat flow direction of the motor,all equivalent thermal resistance are connected to form an equivalent heat path model.Then,the equivalent thermal circuit model is solved to obtain the temperature distribution in the motor,and the results are analyzed,which provides a reference for the design and temperature prediction of permanent magnet synchronous motor for electric bus.Finally,the mathematical model of the power system of the pure electric bus is established through theoretical calculation,and the parameters of the whole vehicle and the driving motor are matched.In order to ensure the rationality of the designed motor in practical engineering application,the dynamic model of the whole vehicle is established by using the moto-CAD simulation software,and the simulation experiments of the matching scheme between the electric bus and the driving motor under different working conditions are carried out.