Fractional Sliding Mode Based Speed Tracking Control Of PMSM

Permanent magnet synchronous motor(PMSM),which is a promising energy-saving and environment-friendly motor with small vibration,compact structure,wide speed range,strong overload capability and high reliability.However,as a kind of nonlinear system with external disturbance,complex and strong coupling,PMSM servo system has dynamic parameters such as parameter perturbation and uncertain external disturbance,which make the dynamic performance of the permanent magnet synchronous motor servo control system decrease.In order to improve the control precision of the PMSM servo system,many scholars at home and abroad have done a lot of research.Based on the existing research,this paper focuses on the off-line parameter identification,disturbance rejection and speed tracking control of PMSM.The main research contents and innovations are as follows:(1)For the problem that the stator resistance and inductance of PMSM are easily affected by factors such as temperature rise and magnetic saturation,which leads to the reduction of the accuracy of electrical parameters,a fractional order adaptive sliding mode based PMSM parameter identification method is proposed.By selecting appropriate state variables,the driving system and response system are established.Then a fractional order adaptive sliding mode controller is designed to make the response system desynchronize and track the driving system.When the two systems are fully synchronized,the error between the estimated parameters and the actual parameters is asymptotically stable and the parameters of PMSM are identified.Finally,the effectiveness of the proposed parameter identification method is verified by numerical simulation.(2)For the PMSM control system with uncertain factors such as parameter perturbation and external disturbance,a disturbance observer(DOB)based fractional-order differential sliding mode control method is proposed.Firstly,to reconstruct the uncertain external disturbance,the disturbance observer is designed by Lyapunov stability theorem.On this basis,a saturation function based fractional-order sliding mode controller is proposed to improve the chattering phenomenon of sliding mode control.Then,the disturbance reconstructed by disturbance observer is introduced into the controller to offset the influence of external disturbance on the system and improve the system performance.Finally,the effectiveness of the designed controller is verified by simulation.(3)For chattering problem of fractional sliding mode control in PMSM control system,a disturbance observer based fractional complementary sliding mode control method is proposed.A new sliding surface is designed by combining the generalized sliding surface with the complementary sliding surface.The stability of the sliding surface and the existence of the controller are proved by the fractional Lyapunov stability theory.The controller can effectively reduce the system tracking error,improve the system response speed,and further weaken the chattering phenomenon.The effectiveness of the controller is verified by simulation and experiment.