Chattering-Free Sliding Mode Control Method And Its Application In Permanent Magnet Synchronous Motor Control

With the continuous development of automatic control theory,sliding mode control is characterized by its fast response speed,low requirement on the precision of the controlled object model,strong robustness against system uncertainties and external disturbances,and easy implementation of system decoupling control.The advantages have been universally applied in many fields.However,due to the unique switching characteristics of the sliding mode control,the control discontinuity is easily caused,which leads to the occurrence of high-frequency chattering,which limits its application in more fields.In this dissertation,a chattering-free sliding mode control method is proposed for the sliding mode chattering problem by integrating the extended state observer with the sliding mode control.The introduction of the extended state observer enhances the immunity of the sliding mode control system.At the same time,a class of nonlinear smooth functions are used in the design of the extended state observer and the sliding mode control law,which is very good for avoiding the sliding mode.The chattering problem caused by the high-frequency switching of the sign function.The main research contents of the paper are as follows:(1)Based on the analysis of the theory of sliding mode control for the chattering problem of sliding mode control,the causes of the chattering,the hazards and the significance of the elimination of chattering,and several typical methods for suppressing buffeting are obtained.(2)Studied a chattering-free sliding mode control method based on an extended state observer,which compensates for the deficiency of the classical PID(Proportional-Integral-Differential)control theory for the ability to adjust the complex nonlinear system and the sliding mode control Immunity and deficiencies between the elimination of chatter.Using the excellent observation characteristics of the extended state observer,the unknown functions in the nonlinear uncertain system are observed and estimated.At the same time,after analyzing the functional properties of a class of nonlinear smooth functions,this function replaces the extended state observer and the sliding mode.The non-linear chattering sliding mode controller is designed to approach the non-linear combination of powers in the law.The stability of the system is proved by the Lyapunov function method.(3)The studied chattering-free sliding mode control method is applied to the control of a permanent magnet synchronous motor.For the permanent magnet synchronous motor is a multi-input multi-output nonlinear strong coupling object,the coupling quantity and the unknown quantity in the mathematical model can be regarded as unknown disturbances,and the state observer is used for observation compensation.Both the speed loop and the current loop are controlled by a chatter-free sliding mode controller,which enhances the control quality of the permanent magnet synchronous motor speed control system.The simulation results show that the proposed control method can effectively solve the influence of uncertain factors on the sliding mode control system,and has good control quality and robustness in the control of the permanent magnet synchronous motor speed control system,and can be effective Solve the chattering problem of the sliding mode.