Generation Mechanism And Optimization Design Of Torque Ripple And Electromagnetic Noise In Claw-pole Alternator

With rapid development of automobile in recent years, claw-pole automobile alternators have been used with an annual production of above 400 million because of the advantages of reliable running, lower economic cost and better performance. However, electromagnetic noise and torque ripple of claw-pole alternator are becoming a more and more significant topic of research which prevents the gradual development of claw-pole alternator severely, and researchers are paying attention to it. This paper investigated the torque ripple and electromagnetic noise of automobile claw-pole alternators, and analysis of generation mechanisms and control technology are given. The achievements of this paper main include the following:1. The claw-pole was equaled to the model of cantilever beam. Claw-pole’s deformation for rotating centrifugal force and electromagnetic exciting force were considered by the basic theory of air-gap magnetic field and mechanical principle.2. In connection with characteristics of claw-pole alternator, the origins of ripple torque were presented, the calculation formulas of ripple torque were deduced, the method of torque pulsation reduction was analyzed, and it was proved that there is a strong correlation among pole-arc coefficient, torque ripple and electromagnetic vibration.3. As for noise generation mechanisms, many methods were proposed, such as the claw pole was provided trimming, electromagnetic field tend to be sinusoidal and excitation force waves tend to be reduced; the method based on brazing poles to reduce the centrifugal distortion and electromagnetic noise; the reasonable pole and slot matching; the optimization of installation structure, etc.;4. The optimized claw-pole alternators with low electromagnetic noise were produced, an experiment platform was designed to illustrate the feasibility of the scheme by experimental data, and experimental results of torque ripple and electromagnetic noise were analyzed.This paper systematically studied the issue of torque ripple and electromagnetic noise in claw-pole automobile alternator, and some primary conclusions of generation mechanisms and control technology were obtained. Research on this paper provided reliable theoretical and technical support of high-performance alternator, and important theoretical significance and practical value were on this paper.