Research On BLDCM Sliding Mode Variable Structure Control Based On Improved Exponential Reaching Law

Brushless DC motor is widely used since its excellent performance.BLDCM is a non-linear system,it has complex internal electromagnetic environment,and its internal parameters will change with the operation of the motor.Therefore,the traditional PI control way can no longer meet the precise control requirements of BLDCM.However,sliding mode control method is suitable for non-linear systems,its performance is stable,can resist the system itself and some external interference,can meet the control requirements of BLDCM.This paper is based on the theory of sliding mode variable structure control and non-singular fast terminal sliding mode analysis,and studies BLDCM sliding mode variable structure control from the perspective of improving exponential reaching law,in order to further improve the performance of sliding mode variable structure control.The specific research content are as follows:First of all,this paper summarizes the research background of this system and the significance,analyzed the BLDCM control method,the sliding mode variable structure control and improvement of index reaching law of sliding mode control research status at home and abroad.The basic structure,mathematical model and working principle of BLDCM are expounded,and the control principle of six-step commutating is emphatically analyzed.The basic simulation model of BLDCM six-step commutation control system based on PI control is built.Next,aiming at the shortage of PI control,based on the introduction of sliding mode variable structure control,studying speed controller of non-singular fast terminal sliding mode with index reaching law,to solve the issues of PI control.For further shorten the time it takes for the motor to reach steady state,based on the reaching law,make certain improvements to the exponential reaching law,studying a variable speed exponential reaching law NFTSM speed controller.And use Lyapunov function to prove controller is stable.After simulation analysis,on the premise of not affecting the steady-state accuracy of the controller,the NFTSM speed loop controller with variable speed exponential approach law achieves the expected goal.Then,in order to realize the sensorless control of BLDCM,the sensorless control principle of BLDCM line inverse emf crossing zero method is analyzed,discussing the specific reasons for buffeting caused by traditional sliding mode observer.On this basis,from the view of improving the exponential reaching law,linked to the non-singular fast terminal sliding mode,studying a NFTSMO with improved exponential reaching law.Use the Lyapunov function to verify the stability of the studied sliding mode observer.By simulation,the improved exponential reaching law NFTSMO can well solve the issues of serious chattering and poor observation accuracy of traditional sliding mode observers.Finally,a set of BLDCM system hardware control platform based on Bluetooth wireless control with "GD32F303 chip" as the core is completed.Based on this platform,the speed control of the motor is verified experimentally by using the variable speed exponential reaching law NFTSM,which proves the effectiveness of the researched controller.