Research On SHEPWM Control Technology Of Permanent Magnet Synchronous Motor Speed Control System

Permanent magnet synchronous motor(PMSM)is widely used in AC speed regulation because of its small size and high power factor.However,due to the limitation of switching loss and heat dissipation of inverter switch tube,the switching frequency of inverter is usually less than 1000 Hz,and the harmonic content of current increases with the increase of motor speed,so it is necessary to redesign the modulation strategy of permanent magnet synchronous motor speed control system.Usually,asynchronous modulation is selected at low frequency,piecewise synchronous modulation is selected at intermediate frequency and square wave is selected at high frequency.In this paper,the permanent magnet synchronous motor speed control system is taken as the research object,and the specific harmonic elimination pulse width modulation technology(SHEPWM)is studied by using vector control technology,and the pulse width modulation strategies of low frequency asynchronous space vector pulse width modulation(SVPWM),intermediate frequency segmented synchronous SVPWM and SHEPWM are adopted.This modulation strategy can avoid the problems of excessive storage of SHEPWM switching angle at low frequency and high harmonic content at intermediate frequency.The improved ant colony algorithm is used to solve the SHEPWM switching angle equations.Compared with the basic ant colony algorithm,the switching angle obtained by the improved ant colony algorithm has the advantages of fast convergence speed and high solution accuracy.Compared with the basic ant colony algorithm and Newton iterative method,the simulation further illustrates the superiority of SHEPWM technology based on the improved ant colony algorithm.Finally,the SHEPWM simulation model of permanent magnet synchronous motor speed control system is built by using MATLAB/Simulink software.The simulation results show that the permanent magnet synchronous motor runs stably,the current harmonic content is low and the torque ripple is small.In the process of switching different modulation modes,the voltage vector equivalent method is used to realize the smooth switching between SHEPWM and SVPWM The method of current harmonic zero crossing is adopted to realize the smooth transition between different carrier ratios SHEPWM.