Research On Performance Of Permanent Magnet Synchronous Motor System Based On Direct Torque Control

Permanent Magnet Synchronous Motor(PMSM)has been widely used in various industries because of its high output efficiency,high output and excellent working performance.Direct Torque Control(DTC)has the advantages of simple coordinate transformation and easy control of torque.However,there are also some shortcomings,such as large torque ripple and increased wear and tear.At the same time,in order to obtain rotor information in DTC control,mechanical sensors are usually required,which results in high cost and limits the use environment of PMSM.Therefore,it is necessary to study the position-free sensing technology.In this paper,the performance of traditional DTC and SVM-DTC control methods is analyzed.Based on this,the torque ripple suppression method and sensorless control technology are studied.The main research contents are as follows:(1)Aiming at the problem of traditional DTC torque ripple in PMSM,this paper proposes a new improvement strategy,which introduces zero voltage vector and Super-twisting sliding mode speed controller into traditional DTC.The simulation shows that the improved DTC torque ripple is significantly reduced and the speed characteristics are significantly improved.(2)The working principle of PMSM based on space vector modulation direct torque control(SVM-DTC)is analyzed.It is verified by Matlab/Simulink simulation.Compared with the traditional DTC method,the torque ripple can be significantly reduced.The speed performance improvement is not obvious.A new speed controller combining single neuron PID and traditional PID is introduced.The simulation proves that the new control strategy improves the speed performance of SVM-DTC system.(3)When the traditional Sliding Mode Observer is used to measure the rotational speed and rotor position of PMSM,the chattering phenomenon affects the observation accuracy.This paper improves the traditional SMO from three aspects,firstly using the variable saturation function sat(s)replaces the symbol function sgn(s),secondly introduces a back-EMF observer,and finally uses a phase-locked loop to extract the position information of the rotor.The effectiveness of the proposed strategy is verified by MATLAB.The simulation shows that the speed tracking is more accurate and the rotor position estimation is more accurate.