Research On Low Noise Pulse Width Modulation Technology Of PMSM

At present, the PWM technology was widely used in variable frequency speedregulation system, which makes the power switch device are turned on and off in adetermined way, so the output voltage of inverter contains a large number of harmoniccomponents, the harmonic enhances the vibration of the motor, and produce a intolerableelectromagnetic noise. to change the spectral distribution of harmonic.This thesis putsforward a hybrid random modulation technology, and make many related experiment in thepermanent magnet motor experimental platform, this thesis mainly research contents are asfollows:Firstly, the development and application of the random PWM technology is summedup, the basic principles and classification of the random PWM technology is summarized,random number generation methods are introduced, and a novel hybrid random PWMtechnology was proposed.Secondly, permanent magnet synchronous motor frequency conversion speed controlsystem model based on the Matlab simulation software is designed, fixed switchingfrequency modulation, cycle frequency modulation, random switching frequencymodulation and mixed random switching frequency modulation technology are simulatedin this paper, the simulation results and comparative analysis of the four kinds of PWMtechnique show that hybrid random switching frequency modulation technology can moreeffectively spread spectrum.Besides, a220W permanent magnet synchronous motor experimental platform isbuilted, and detailedly introduced parts of the hardware circuit design and software designof the permanent magnet motor experimental platform.Finally, the experimental result of the different switch frequency effects on currentwaveform show that the current riple decreases with switch frequency increases, and thehigh harmonics concentrated in the switching frequency and its multiples. By the currentwaveform spectrum analysis of fixed switching frequency, random switching frequencyand mixed random switching frequency modulation,the novel hybrid random switchingfrequency modulation technology can not only more averagely distribute the harmonic in the whole spectrum, but also reduce the performance requirements of random number.