Torque Characteristics Analysis Of Interior Permanent Magnet Synchronous Motor Used For Electric Vehicle

In this paper,the permanent magnet synchronous motor for electric vehicles had high requirements on the torque characteristics to meet the short-time starting,acceleration and overload performance of the automobile.A interior permanent magnet synchronous motor(IPMSM)for an electric vehicle with 80 kW uneven air gap was used.For the research object,the torque characteristics were studied on the basis of electromagnetic characteristics.Firstly,according to the parameters of the permanent magnet synchronous motor for electric vehicles,the main dimensions of the motor were determined,and the structure of the stator and rotor was designed and the structure of the rotor was improved-the uniform air gap structure was changed to the uneven air gap structure,so that the air gap magnetic density waveform was rectangular to sine wave.The experimental values of the prototype and the electromagnetic design program values were compared.Secondly,establishing the physical model of permanent magnet synchronous motor for electric vehicles,the influence factors of torque of the permanent magnet synchronous motor were analyzed.The finite element method was used to calculate the no-load and load magnetic-density distribution of the permanent magnet synchronous motor,and the air-gap magnetic-density waveform and its Fourier decomposition’s harmonic content were obtained.Calculated the no-load back electromotive force waveform and d,q-axis inductance of permanent magnet synchronous motor,analyzed the cogging torque,rated electromagnetic torque and peak torque characteristics of the permanent magnet synchronous motor,and the performance of permanent magnet synchronous motor with uniform air gap and uneven air gap were compared and analyzed.In order to verify the correctness of the theoretical analysis,an experimental test platform was set up to compare and analyze the simulated values of the rated speed-torque,rated speed-power,speed-peak torque curve and experimental values.Finally,the factors affecting the peak torque of permanent magnet synchronous motor for electric vehicles were analyzed.Based on the modal analysis,the random vibration analysis of the IPMSM rotor were carried out,and then the influence of the eccentricity caused by random vibration on the peak torque of IPMSM was analyzed.And the rotor unevenness,permanent magnet slot shape,material,angle,inter polar distance,weight reduction hole area and position on peak electromagnetic torque of interior permanent magnet synchronous motor were further researched.It presented a basis for electromagnetic design and overload characteristic analysis of interior permanent magnet synchronous motor for electric vehicles.