| Electromagnetic noise is the main contribution to the noise of automotive drive motors,its sound pressure magnitude and spectral characteristics directly affect the NVH performance of an electric vehicle.Electromagnetic force is the excitation source of electromagnetic noise.Under the effect of electromagnetic force,the motor housing and stator are deformed to generate vibration.The deformation of the stator will change the structure of the air gap and affect the distribution of the magnetic field of the air gap so that the electromagnetic force will change.Finally,it will affect the vibration and noise characteristics of the motor in turn.At present,there are few studies on this kind of magneto-machanical coupling,so it is of exploration significance.This article uses a permanent magnet synchronous motor driven by a vehicle as the research object.Through the combination of theory,simulation and experimentation,this paper analyzes the electromagnetic vibration and noise characteristics of the motor based on the study of the electromagnetic force fluctuation characteristics,structural dynamic characteristics of the motor and effect of shell deformation on magnetic-mechanical coupling analysis of motors.The main contents of this paper are:First of all,the characteristics of the electromagnetic wave of a motor are described theoretically.Then,through the finite element analysis model of the three-dimensional electromagnetic field of the motor,the electromagnetic force of the stator tooth is simulated,at the same time,its spatial distribution characteristics and spectral characteristics are analyzed.The analysis results are consistent with the theoretical derivation results.Considering the superposition effect of silicon steel sheet and the influence of winding quality,a finite element analysis model of the motor stator system structure is established and free modal analysis is performed.At the same time,the correctness of the structural finite element model is verified by modal experiments.On this basis,This paper makes a constrained modal analysis of the motor stator system that is mounted on the gantry.Based on this,the vibration response of the motor running at 3600 r/min was predicted.In order to study the influence of the deformation of the casing on the magnetic-machanical coupling analysis of the motor,a two-way coupling analysis is performed on the electromagnetic field and the structure field of the motor.The results show that for the permanent magnet synchronous motor with large stator stiffness,before and after considering the stator deformation,the magnetic field distribution of the air gap,the maximum electromagnetic force,and the maximum deformation are all less changed.It can be concluded that shell deformation has no effect on magnetic-solid coupling analysis of the permanent magnet synchronous motor with large stator stiffness.The electromagnetic force calculated by the electromagnetic field simulation is loaded on the grid of the stator structure,and the vibration response of the shell surface is calculated by the modal superposition method to obtain the vibration characteristics of the motor frequency spectrum.Based on this,the electromagnetic noise of the motor is calculated by the ATV method,and the acoustic response characteristics of the field are obtained.According to the standard GB/T10069.1-2004,the motor is tested in an accelerated and steady-state noise condition in a semi-anechoic room to obtain the noise characteristics of a permanent magnet motor for use in vehicles.The sound pressure spectrum curve obtained from the noise experiment was compared with that from the simulation to verify the correctness of the simulation method. |
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