Analysis On Electromagnetic Vibration Characteristics Of Vehicle Alternator

Currently,the major manufacturers are paying close attention to the vibration and noise of vehicle alternator.With the development of manufacturing technology and the development of noise reduction technology,the mechanical vibration noise and aerodynamic vibration noise of alternator are suppressed,but the electromagnetic noise caused by electromagnetic vibration is highlighted.Therefore,it is of great significance to study the electromagnetic vibration of vehicle generator.In this paper,a typical AC claw pole alternator is used as the research object.The electromagnetic vibration and its influence factors of the alternator are studied by the method of finite element simulation and experiment.According to the electromagnetic noise and vibration problem of “JFZ1741” alternator of a passenger car,the vibration and noise are tested under cold non-loading and hot loading conditions,and the results show that the electromagnetic vibration will increase the level of noise at the rotate speed ranged from 1500 to 5000 rpm under hot loading condition,and the 36 order vibration and noise is the main component of the speed range.The vibration and noise signals of the peak speed of 3000 rpm are measured to be compared with the simulation.In this paper,the electromagnetic model of alternator is established by using the 3D modeling software CATIA and the electromagnetic simulation software ANSOFT Maxwell.The constant voltage excitation is added to the rotor winding and the external circuit of the stator is built after the load is replaced by the fixed value resistance.By separating the stator teeth,the accuracy and the efficiency of the electromagnetic force can be improved.Based on ANSOFT Maxwell,the electromagnetic field of 3000 rpm is calculated,and the electromagnetic force of a stator tooth is extracted.The electromagnetic force has good periodicity,and the results of spectrum analysis show that the 12,24,and 36 order have obvious peak value.The simulation model of stator is simplified based on its structural characteristics,the entity model is established to replace the sliced structure of stator core,and stator winding is modeled based on equivalent volume method,the maximum error of test and simulation is 7.1%,which validated the reliability of stator model.On this foundation,the whole model is built,and connections between assembly parts are reasonably set,the errors of modal simulation results and the experimental results are less than 7.4%,the finite element model can be used to vibration response analysis.In ANSYS Workbench,the electromagnetic force is automatically loaded on the stator teeth in the form of spectrum.The radial acceleration of stator surface was extracted,compared with the test results,the results are consistent with each other in the spectrum except mechanical vibration interference in low frequency,and the 36 order vibration amplitude of the peak value are close to.Based on the simulation system,the factors that affect the electromagnetic vibration,such as air gap,chamfer,claw pole size and eccentricity,are analyzed.In this paper,a complete analysis system of the electromagnetic vibration of the alternator is established with the experiment and finite element coupling simulation.It provides a reference for the control of the electromagnetic vibration of the motor,and have some certain actual engineering significance.