Research For Radiation Noise Of Electric Vehicle PMSM

With the rapid development of new energy vehicle industry,battery electric vehicles have been widely concerned by major automobile factories.Due to the difference of powertrain between battery electric vehicle and traditional vehicle,the noise excitation source of the vehicle is obviously different.Because of electromagnetic design,the structure of the motor stator manufacturing tolerance and other factors caused by internal motivation and the road load change under the influence of external incentives,the drive motor of battery electric vehicle powertrain,such as working vibration and noise radiate through the air and structure into the car,affect the driving experience of people in the vehicle.The main factors affecting NVH performance come from three categories: powertrain and transmission system,road and tire excitation,and high-speed wind noise.Reducing vibration and noise of driving motor can improve vehicle NVH performance effectively.This paper is based on the PMSM(permanent magnet synchronous motor)NVH performance improvement project of a developing vehicle of BJEV.By optimizing the electromagnetism and structural design of the driving motor,this paper studies the cause of the noise of PMSM for vehicle and the influencing factors of radiative noise.Firstly,the finite element model of the motor is established and the modal analysis is carried out to obtain the motor’s natural frequency and related vibration modal.The simulation results are compared with the modal test results to verify the correctness of the finite element model and modal analysis results,which lays a foundation for acoustic analysis.Secondly,the two-dimensional motor simulation model is established to carry out the electromagnetic field simulation calculation,and the magnetic field density at a specific speed is converted into the electromagnetic force,and the dual Fourier transform is performed to obtain the spatial order in the time domain and frequency domain.The nodal force on the stator teeth is generated and loaded into the finite element model.Then,based on the finite element model of the motor shell,the free modal data of the motor and the dynamic excitation of electromagnetic excitation to the stator core are obtained,and the acoustic finite element and acoustic boundary analysis are used to calculate them.The simulation results of noise radiation of different electromagnetic schemes and the test results of the whole vehicle are compared to verify the effectiveness of the acoustic finite element simulation method.Finally,the practical effect of reducing the radiated noise of the motor was verified by the vehicle test with the feasible engineering noise reduction optimization scheme.The improved motor was tested by optimizing the structure shape of permanent magnet and the stator filling and sealing.The noise result before and after the optimization was compared,and the effectiveness of the motor noise reduction design was proved.