Research On Permanent Magnet Synchronous Motor Servo System Based On Sliding Mode Control Method

In the control of permanent magnet synchronous motor,traditional PI control is not suitable for high demand applications because of its poor anti disturbance ability.Sliding film control is one of the schemes to improve the robustness of PMSM control system.There have been successful cases in the field of application,but there are still many problems to be solved.In this paper,the research work will be carried out on the sliding film control of permanent magnet synchronous motor.Firstly,the paper introduces the research status of PMSM speed servo system at home and abroad,deduces the mathematical model of PMSM,and based on this,builds a simulation model with changeable motor parameters.Through the simulation of double closed-loop speed control system,the correctness of the self built motor model is verified.Then,based on the traditional sliding film control,the linear quadratic optimal control is introduced,and the optimal sliding mode control is produced by combining the two.The related theoretical basis and the design of the optimal sliding mode control are introduced in detail.The optimal sliding mode controller is applied to the d-axis current control instead of the traditional PI control.The simulation results show that the control strategy is better than the traditional PI control in stability and robustness.Finally,the feasibility of the optimal sliding mode control is verified by experiments.Aiming at the cause of chattering in traditional sliding mode control,which is the discontinuous control variable acting on the first derivative of sliding mode surface variable,a high-order sliding mode control is proposed,which applies the discontinuous control variable on the high derivative of sliding mode surface variable,and then makes the control variable acting on its first derivative continuous,weakening chattering.The theoretical basis of high order sliding mode control and the second order sliding mode control are introduced in detail.The second-order sliding mode controller is used to replace the PI controller of speed and q-axis current.Through analysis and simulation,the performance of the control system under the control strategy is studied deeply.It is concluded that the system is better than the PI controller in terms of rapidity and robustness when the second-order sliding mode controller is used,but the PI controller is better in terms of stability.Based on the second-order sliding mode control,singular perturbation theory is introduced to combine the two.The original system is decomposed into two reduced order subsystems,and the controller is designed respectively.The superiority of this method is verified by simulation experiments.The results show that the proposed control strategy has better robustness,good dynamic and steady-state control performance and good stability than the second-order sliding mode control.Finally,the control effect of second-order sliding mode control and singular perturbation second-order sliding mode control are verified and compared by experiments.There are 26 figures,2 tables and 85 references in this paper.