Research On Direct Torque Control System Of Permanent Magnet Synchronous Motor Based On Double Sliding Mode

Permanent magnet synchronous motor(PMSM)has the advantages of stable structure,large starting torque,energy saving and easy control,so it has been widely used in industrial production.Direct torque control(DTC)of permanent magnet synchronous motor has the advantages of simple control and rapid response,so it is widely used in PMSM speed control system.In this paper,the traditional DTC system has the disadvantages of large torque and flux ripple and unstable switching frequency,and the improvement and optimization design are carried out.Aiming at the defects of the traditional DTC system,such as unstable switching frequency and large flux flux and torque ripple,the space voltage vector pulse width modulation(SVPWM)technology and the superhelix algorithm in the second order sliding mode were introduced to design the superhelix sliding mode controller(STSMC),and the hysteresis control of flux flux and torque in the traditional DTC system was replaced by STSMC.Through simulation analysis,the optimized DTC system reduces the flux and torque ripple,and improves the control accuracy of the system.The rotor information acquisition accuracy of permanent magnet synchronous motor is very important for the performance and reliability of PMSM control system.The traditional PMSM uses position sensors to determine the motor speed and rotor position.The traditional mechanical sensors are not only susceptible to the adverse environment,but also make the structure of PMSM more complex.Therefore,in this paper,the rotor position information is obtained by using SMO algorithm,and combined with the optimized DTC system,a direct torque control method of PMSM based on double sliding mode is proposed.Traditional SMO systems have problems such as poor observation accuracy and high frequency chattering.Therefore,a sensorless control strategy based on double filter is proposed in this paper.After the back electromotive force is extracted by the traditional SMO algorithm,a low pass filter is usually applied to remove the high frequency signal to improve the observation accuracy.The high-order sliding mode has the effect of weakening chattering.In this paper,superspiral algorithm is introduced to design STSMO to suppress chattering in the system.At the same time,the low-pass filter is replaced by a variable frequency low-pass filter,and Kalman filter is added to form a dual filter structure,which further filters out noise and interference signals,and reduces the ripple in the estimated back electromotive force.At the same time,the saturation function is used to replace the original sign function to reduce chattering.Finally,the position information of the rotor is obtained through the phase-locked loop.The simulation results show that the optimized STSMO control system has good dynamic and static stability,can effectively suppress system chattering,and greatly improve the observation accuracy of rotor position.To verify the feasibility and effectiveness of this algorithm,an experimental platform of PMSM sensorless control system was designed and built.Experimental results show that the optimized PMSM direct torque control system based on double sliding mode can effectively suppress system chattering,and has better control accuracy and steady-state quality.