Analysis And Optimization Of Electromagnetic Vibration And Noise Of Permanent Magnet Synchronous Motors For Vehicles

Global energy shortages and environmental degradation have led to a gradual ban on the sale of pure fuel vehicles,and the vigorous development of new energy vehicles has become a strategic choice for automobile industries in various countries,as is China.At present,permanent magnet synchronous motor(PMSM)has many advantages such as high efficiency,large starting torque and high reliability,which accounts for more than 90% of new energy vehicles in China.However,motor squealing caused by high frequency electromagnetic vibration and noise has been widely concerned for a long time.For vehicle PMSM,there is electromagnetic force between stator and rotor,among which tangential electromagnetic force is mainly used to generate electromagnetic torque,while radial electromagnetic force maintains the alternating magnetic field between stator and rotor and causes radial vibration of stator,which is the main source of vibration and noise of motor.This paper starts with optimizing radial electromagnetic force to vehicle PMSM,and the problem of electromagnetic vibration and noise of motor has been studied.Firstly,this paper has studied the influence of the stator assembly material parameters on the structural modal of permanent magnet synchronous motors,and has established an accurate finite element model of the motor structure.To this end,the modal test of the stator assembly of the motor was carried out,and the simulation modal analysis of the stator assembly considering the anisotropic material properties was carried out,and the error between the two was kept within 5.5%;on this basis,the software Hypermesh was used to complete for the assembly of the finite element motor housing,controller housing and other components,the error between the simulation modal results of the motor and the experimental modal results is within 9.3%.Secondly,this paper has analyzed the radial electromagnetic force on the stator teeth surface of PMSM through the analytical method and the finite element method to provide theoretical and practical guidance for the subsequent optimization of electromagnetic force.First,according to the Maxwell tensor formula,the radial electromagnetic force wave per unit area of stator teeth surface is obtained analytically,and the main time harmonic and space harmonic components of the radial electromagnetic force are determined analytically when the motor is powered by no-load and sinusoidal current.Second,through the finite element simulation,the radial air gap magnetic density and radial electromagnetic force distribution of the motor under no-load and sinusoidal current supply are obtained,and the correctness of the analytical method is verified,and the simulated electromagnetic force is used as the excitation source on the surface of the stator teeth for subsequent analysis of the forced vibration response.Then,this paper has studied the forced vibration and radiated noise of the permanent magnet synchronous motor under the action of electromagnetic force,and has established an accurate motor multiphysics vibration noise prediction model.First,the motor vibration and noise bench test was carried out to obtain the vibration acceleration of the motor shell surface and the near-field radiated noise at the test points;second,using the acoustic simulation software LMS Virtual Lab,the forcing vibration response analysis based on the principle of modal superposition and radiated noise analysis based on the boundary element method were performed,so the vibration and noise distribution at the same measurement points were obtained;third,the test results are used as the optimal target,through parameter adjustment,the 24 th and 48 th order vibration and noise distribution between simulation and test results have reached a good consistency.Finally,based on the accurate prediction model of multi-physics vibration noise of the motor,for the 48 th order vibration noise that causes the motor howling,this paper has proposed a rotor slotting scheme to optimize the 48 th order radial electromagnetic force,and reduce the 48 Order vibration noise level.First,the effect of the rotor auxiliary slot space position on the amplitude of the 48 th order electromagnetic force was analyzed by simulation,and the optimal slot position was determined as R2 slot;second,on the basis of the determination of the slot position,the geometric parameters of the auxiliary slot was studied to obtain the influence on the amplitude of the 48 th order electromagnetic force and the performance of the motor,and finally has determined the appropriate slotting geometric parameters.The simulation shows that the slotting scheme has reduced the peak noise of the motor at a steady speed by about 2dB.