Research On Direct Torque Control For PMSM Speed ​​Control System

Compared with other motors, PMSM has small volume, high operationefficiency. In recent years, the research like PMSM-DTC has been sufficientlyimproved with the updating for power electronic devices and the simplificationof control algorithm. But, the flux and torque ripple limit the application ofDTC.In this study, traditional PMSM-DTC and SVM-PMSM-DTC are introducedon the basis of mathematical models. Based on the basis of the relevantparameters, traditional control scheme is simulated by matlab/simulink. Resultswere compared, and the experimental results prove that: The use of SVPWMwith PMSM-DTC has the function of reducing the torque ripple and the currentwaveform distortion, and improving the utilization of DC voltage.The second, low pass filter is used with DTC. And in this study, a new wayto judge stator flux space vector’s sector is introduced. After the analysis ofcorresponding theoretical basis, simulation experiment is used to proof them.Results were compared, and the experimental results prove that: low pass filtercan clear up high-order harmonic and it also can reduce the harmonic and noise.We can know stator flux linkage waveform and current waveform are well. Atthe same time, the new method replaces the traditional one perfectly, and it canreduce programming complexity.The third, in order to solve the issues that large space, expensive, prone tointerference by a poor working environment with speed sensor. Sensorless speedcontrol is used with DTC. Firstly, sensorless speed control and the simulationmodule are introduced in this study. Then, based on the simulation module ofthe third and forth chapters, new stator flux space vector’s sector is used in thesimulation with sensorless speed control. Results were compared, and theexperimental results prove that: The new method replaces the traditional oneperfectly. And sensorless speed control combines with DTC very good.