Research On Position Sensorless Control Of Surface-Mounted Permanent Magnet Synchronous Motor Based On Sliding Mode Control

Permanent magnet synchronous motor(PMSM)has been widely used in AC speed regulation systems due to its high dynamic performance,high efficiency,lightweight,and many other advantages.Currently,motor control is developing towards high efficiency,high performance,high reliability,and low cost.Generally,PMSM control systems are equipped with mechanical position sensors,which pose problems such as high system cost,reduced reliability and limited application.PMSM position sensorless control technology can effectively avoid these problems.In this thesis,the object of study is surface-mounted permanent magnet synchronous motor,and the research on PMSM position sensorless control is carried out based on sliding mode control method under the framework of speed and current dual closed-loop vector control strategy with _di=0 control.Firstly,this paper introduces PMSM vector control and sliding mode control,and then vector control based on traditional PI and sliding mode control is simulated on the MATLAB/Simulink platform.The results show that traditional vector control has shortcomings such as large overshoot,poor rapidity and poor anti-disturbance ability,and cannot achieve high-performance control.Secondly,in view of the shortcomings of traditional vector control,based on the exponential reaching law and an integral terminal sliding mode surface,a PMSM cascaded terminal sliding mode control system based on nonlinear disturbance observer(NDOB)is designed,and its stability is proved.In this system,both the speed loop and current loop based on the traditional PI controller or sliding mode controller are replaced and cascaded by the terminal sliding mode controller,and a nonlinear disturbance observer is designed to enhance the anti-disturbance performance.Through comparison simulation with traditional vector control and cascaded terminal sliding mode control,it is verified that the performance of the NDOB-based PMSM cascade terminal sliding mode control is significantly improved in various aspects,and can achieve high-performance control with high accuracy and fast response.Finally,an improved super-twisted sliding mode observer is combined with the PMSM cascade terminal sliding mode control(with position sensor)system based on NDOB to form a PMSM composite position sensorless control system,and comparative simulation using MATLAB/Simulink is performed.Simulation results show that the PMSM composite position sensorless control system based on traditional sliding mode observer has severe chattering and severe back EMF distortion.Compared with the system before the improvement,the PMSM composite position sensorless control system based on an improved super-twisted sliding mode observer further enhances the ability to resist disturbances and chatter while maintaining the good rotor position and back electromotive force observation performance,and expands the range of effective speed regulation.The improvement effect and rationality of the PMSM composite position sensorless control system proposed in this paper,which combines improved super-twisted sliding mode observer and PMSM cascade terminal sliding mode control based on nonlinear disturbance observer,are verified by the comparative simulation.