Analysis Of Electromagnetic Noise Of Automobile Alternators Based On Statistical Energy Analysis

Claw-pole alternator, with the characteristic of simple manufacture, low costand reliable operation, was widely used in the field of new energy power generation,automotive industry and so on. With the development of industrial technologywidening application of the claw pole alternator, the demand on the claw polealternators is becoming higher and higher. The size of miniaturization of claw polealternator and the increasing demand for the output power and output performance,vibration and noise were considered as important indicators to judge the merits ofmotors. During the operation of claw-pole alternator, the value of electromagneticnoise was large, making it an important factor for restricting claw pole alternatordevelopment. The motor structure was damaged, the motor life was reduced, theefficiency of the motor and other technical indicators were affected and the reliableoperation of the motor was threated significantly. Therefore, the accurate predictionof electromagnetic noise of the claw pole alternator is of great significance forlow-noise claw pole alternator design and optimization.Due to the special structure of the claw pole alternator, the frequencies andvalue of harmonic generated by the alternator during operation at different speedwere distinctive, the complexity of noise and vibration prediction of the claw polealternator was increased. The complex analysis of claw-pole alternator at high-bandfrequency, the impact of mounting structure was not clear, and vibration noiseanalysis also involves a number of areas of acoustics, the magnetic field theory andfinite element method, these factors contributed to the difficulties of the accurateprediction of the claw pole alternator electromagnetic noise, a large number ofexperiments and in-depth research are needed.In this paper, the14v,500w Automobile Alternators was used as the researchobject, the statistical energy analysis method was introduced to analyze thealternator. First, the basic theory and internal parameters of statistical energyanalysis were introduced to build the basic energy balance equation and clearly thebasic principle of the energy flow between the subsystems and experimentalstatistical energy analysis method; Second, in connection with the claw polealternator, subsystems were divided, statistical energy analysis model and theenergy balance equation were established to provide factor equations and the input power equations calculate the radiated sound power of claw pole alternator; andthen, the impact of the installation structure and ripple torque of the alternator wereanalyze; Finally, experimental equipment was introduced and experimental methodwas used to measure the radiated sound power of claw pole alternator. Then thecalculated values were compared with the statistical energy analysis, theadaptability of statistical energy analysis method in the high frequency andaccuracy of the calculation results were validated, the measures to reduce theelectromagnetic noise for claw pole alternator were given, which could help tooptimize the design and actual practice of claw pole alternator in futureapplications.