Based On Improved Random Pulse Width Modulation Technology Research On Vibration Suppression Of Permanent Magnet Synchronous Motor

Permanent Magnet Synchronous Motors have obvious advantages such as low loss,high efficiency and high power density.PMSMs are widely used in household appliances,automobiles and other civil industries,underwater propellers,aerospace and other special industries.At the same time,the vibration and noise problems of PMSMs are gradually exposed with the improvement of residents’ living standards and people’s higher requirements for the living environment in which they live.In the realization of a wide-range frequency conversion speed control system for PMSMs,the drive mode of the motor is mainly driven by an inverter circuit composed of power devices.In the motor drive system,SVPWM is currently the main method of PMSMs speed control.In the SVPWM modulation process,a fixed-frequency carrier signal and a modulation signal are modulated to generate a high-frequency pulse signal that controls the on and off of the power device.During the modulation process,the motor current contains a lot of high-frequency harmonics related to the carrier frequency.At the same time,in the inverter bridge,in order to avoid the simultaneous conduction of the upper and lower power devices of the same bridge arm,the dead time needs to be added.The existence of dead time will lead to dead time effects,resulting in low-order harmonics such as(6k±1)subharmonics in the current spectrum.These current harmonics will generate radial electromagnetic force in the air gap magnetic field of the motor,which will cause the deformation of the stator and rotor of the motor,which in turn causes the motor system to generate strong vibration and noise.This article starts with the control strategy,gives a detailed introduction to the FOC of the PMSMa,and analyzes the vibration source of the vector control system.Then,on this basis,the PMSM is researched on the vibration and noise reduction of the current harmonics in different frequency bands.First,in view of the high frequency switching harmonics caused by SVPWM modulation technology,the random switching frequency SVPWM modulation technology analyzes the problems of uneven dispersion and obvious harmonic bands when dispersing the harmonic energy.Propose an improved random pulse width modulation technology to disperse high-frequency switching harmonics.The sine signal and Markov chain algorithm are used to generate the carrier frequency of the sine random signal,so that the harmonic energy concentrated at the switching frequency and its multiples can be evenly dispersed into a wider frequency spectrum.Obtain a relatively smooth current spectrum with evenly distributed harmonic energy.Secondly,for the(6k±1)sub-harmonic caused by the dead zone effect,the problem of the traditional compensation technology that is not easy to detect the current polarity is improved.The vector operation of the flux linkage increment and the estimation of the back electromotive force are used to form a disturbance voltage observer,which realizes the dead zone compensation strategy without detecting the current polarity,and reduces the amplitude of low-frequency current harmonics.Realize the weakening of the harmonic amplitude of the current full frequency band,and achieve the purpose of suppressing the vibration and noise of the PMSMs.And set up a simulation model in Matlab/Simulink for research,the results show that this strategy has a better harmonic suppression effect.Finally,an experimental platform is built for comparison and verification of experiments.The experimental results verify the effectiveness and superiority of the above-mentioned harmonic suppression strategy and can achieve the purpose of suppressing vibration and noise of PMSMs.