Research On Direct Torque Control Of Permanent Magnet Synchronous Motor Based On Fuzzy Theory

The permanent magnet synchronous motor(PMSM)has the advantages of simple structure,high efficiency and high power density,and is widely applied in the fields of industrial control,automobile and aerospace.The direct torque control(DTC)is a popular control method for pmsm,which has the advantages of fast response speed,simple structure and strong robustness.However,the DTC of the PMSM also has the problems of large torque ripple and poor low-speed performance.In this paper,the fuzzy theory is applied to the control system for the problem of large torque ripple of pmsm,and the improvement strategy is put forward.First,this paper introduces the mathematical model of the different coordinate system of the PMSM,the mutual transformation between the coordinate systems,and the basic principle of the direct torque control.The causes of the torque ripple of the PMSM and the solution to be solved by using the zero vector are discussed.At the same time,the modules of the direct torque control system are set up,and the simulation analysis is carried out.Secondly,aiming at the defect that the hysteresis loop comparator in the traditional direct torque control system leads to a large torque ripple,the flux linkage and the torque hysteresis comparator are replaced by a fuzzy controller,a new fuzzy control rule is designed,and the response speed of the system is improved.The simulation of the model of the fuzzy direct torque control system shows that the torque ripple of the DTC system with improved fuzzy theory is smaller and the performance is better.Finally,in order to improve the response speed and the stability of thewhole system,the traditional outer ring speed PI controller in the original system is replaced by a fuzzy adaptive PID controller,and the fractional order theory is applied to the controller design,so that the range of the PID parameters is widened,and the anti-disturbance capability of the motor is stronger.The simulation model is set up,and the simulation analysis is carried out.The simulation results show that the performance of the DTC system of the PMSM based on the fuzzy theory is obviously superior to that of the traditional direct torque control system.