Research On Sliding Mode Variable Structure Control In Permanent Magnet Synchronous Motor Servo System

With the development of modern industrialization, AC servo system with permanentmagnet synchronous motor is widely used in many areas. Sliding mode control strategy hasmany advantages, such as simple structure, insensitivity to parameter variation and externaldisturbance. By using the advantages of sliding mode, sliding mode variable structure controlbased on the permanent magnet synchronous motor has very important practical significance.Firstly, the mathematical model of the permanent magnet synchronous motor is built inthis dissertation, while vector control strategy on permanent magnet synchronous motor isstudied further deeply. It suggests that control ofid=0can be chosen. Secondly, the controlscheme of permanent magnet synchronous motor servo system is established with threeclose-loop PI regulators by using SVPWM. Finally, a improved sliding mode variablestructure controller is designed on the speed loop and position loop for vector control systemof PMSM, meanwhile the PI controller makes effect in the different stages of systemrespectively. The speed loop controller is designed by simplified sliding mode control methodof variable exponent reaching law, and the position loop adopts sliding mode variablestructure equivalent control method. The position controller improves the system dynamic andstatic performance and robustness by designing switching parameters to the nonlinear variableamong position signal error, sliding mode surface integral and sliding gain.The improved sliding mode control strategy on the servo system of permanent magnetsynchronous motor is simulated using Matlab/Simulink in comparison with the PI controller.According to the simulated results, the novel strategy can improve the systems robustness tothe influence of load and parameters disturbance. It is proved that the improved sliding modecontrol method has the significantly inhibitory action to the inherent chattering, and improvethe PMSM servo system robustness, dynamic and static performance.