Simulation Analysis Of A Vehicle Generator’s Electromagnetic Noise

In recent years, with the rapid development of automobiles in China, more and moreChinese people start enjoying the convenience of vehicles. Meanwhile, people put forwardhigher requirements to the comfort level of vehicle driving. As an essential part of theautomobile electric equipments, vehicle generator’s noise problem also receives moreattention.In normal operation, the air-gap between stator and rotor magnetic field in vehiclegenerator’s will induce a series of electromagnetic force waves, which radial component acton the stator tooth surface, thus resulting in vibration deformation of the generator, and thenradiating electromagnetic noise to the surrounding space. The radial electromagnetic forceand structural intrinsic mode of generator are two key factors affecting the electromagneticnoise. In this paper, the problem of electromagnetic noise of a vehicle generator is studied byusing the finite element analysis method. The contents of this paper include the followings:analyzing of electromagnetic force, analyzing of structural dynamic response and analyzing ofthe acoustic radiation.Firstly, according to the relevant parameters of the alternator, a finite element modal,which is applied to the electromagnetic field analysis, is built up using the Ansoft software,each stator tooth surface is dispersed into the upper and lower portions, the average values ofradial electromagnetic force （including amplitude, frequency, initial phase） on each discretesurface by simulating.Secondly, the intrinsic modes of the alternator structure are calculated by using AnsysWorkbench software, the impact on the intrinsic mode of the alternator structure of thegenerator windings and chassis structure are discussed. Also, the generator’s vibrationresponse upon the electromagnetic force is studied.Finally, the noise level curves and SPL cloud of the vehicle alternator under theinfluence of a electromagnetic force with special frequency are obtained by using the acousticboundary element method after importing the finite element model, the boundary elementmodel of the alternator and the dynamic boundary conditions into the acoustic analysismodule of LMS.Virtual.Lab.In this paper, a complete analysis process for studying electromagnetic noise of thevehicle alternator is established using the methods of numerical analysis. The process and therelative methods build a foundation for further studies of electromagnetic noise problem onthe same class alternator, and it also has some reference value for engineering applications.