Research On The Electromagnetic Noise And Vibration Characteristics Of Automotive Claw-pole Generator

With the popularity of cars in modern society, people pay more and more attention to the comfort of cars. There is close relationship between the comfortableness and the noise in the car, however generator and engine are the main noise sources of interior noise. Because of development of the noise controlling technology in engine, generator noise was highlighted. This topic of subject is automotive alternator, the alternator produce whistlers in low speed. Through the experiment and simulation to study the characteristics of its electromagnetic noise, lay the foundation for reducing its noise.Firstly, analysis noise and vibration of alternator in load and no-load conditions, compared with no-load condition alternator at low speed and in load condition exist obvious noise. The radial electromagnetic force between rotor and stator tooth lead to structure resonance, then radiate this electromagnetic noise. This noise is related to fundamental frequency of order36. Analysis consistency of electromagnetic noise and vibration, the frequency of peak noise corresponds to the frequency of vibration peak.Secondly, based on generator noise vibration test, analysis spectrum characteristics of the radial electromagnetic force by simulation method. Using Ansoft software to set up three-dimensional finite element model of generator, the time step finite element method is adopted for analyzing the transient magnetic field. It is concluded that the magnetic density of air gap between rotor and stator changes, and calculate the radial electromagnetic force. Analysis radial electromagnetic force spectrum in one teeth of stator to determine the main frequency components.Thirdly, by adopting the method of the combination of calculated modes and experimental modes, the inherent frequency and modal vibration mode of generator stator, shell and the machine were analyzed. Then compared with the frequency of radial electromagnetic force, and determined that the electromagnetic noise is caused by the structure resonance.Finally, put forward the improvement measures based on the above results, such as adding damping materials between stator and shell to reduce vibration transmission to shell and improvement shell structure to change its modes. Analyze the improved generators and verify the feasibility of improvement measures.Experiment and simulation verification method is applied in this article to analyze electromagnetic noise and vibration, provide a basis for solving electromagnetic noise of the same type generators. It has a certain reference value for engineering application.