Speed Control And Disturbance Rejection Techniques Of Permanent Magnet Synchronous Motors

This thesis mainly focuses on the investigation of speed control and disturbance rejection techniques of permanent magnet synchronous motors(PMSM).These studies are conducted to improve the control performance and disturbance rejection ability of PMSM.For the speed control problem,extended state observer(ESO)based sliding mode control,disturbance rejection based prescribed performance control and nonlinear dynamics estimation based funnel control are proposed in this thesis separatively.To address the disturbances injected in the system,an extended state observer and an unknown disturbance estimator are proposed separatively.Then composite control algorithms including speed tracking controllers and disturbance estimators are introduced to improve the overall performance of the PMSM system.Finally,simulations and experimental tests are conducted based on the PMSM system to verify the effectiveness and praticability of the proposed methods.Detaied studies are summarized as follows:(1)Extended state observer based sliding mode control for PMSM system.A two-order ESO is introduced by augmenting the lumped disturbances to a new state variable.Then the ESO is used to estimate the lumped external disturbances,and the estimated disturbances can be incorporated into the sliding mode controller.The stability of the closed-loop control system is verified by using Lyapnov theory.The convergences of the tracking error and estimation error are all theoretically proved.To verify the effectiveness and disturbance rejection ability of the proposed strategy,numerical simulations are conducted.(2)Disturbance estimator based prescribed performance control for PMSM system.To cope with external load of PMSM,a disturbance estimator is introduced,which is simple and efficient.The speed tracking error is transformed into a new error variable by using a prescribed performance function.Based on the transformed error and the estimated load disturbance,a feedback control is adopted to control the speed of PMSM.By using Lyapnov theory,the closed-loop system stability is proved and the speed tracking error can be prescribed in the preset small region around zero.Simulation results show that the proposed method can effectively guarantee both the transient and steady-state performance.In addition,the proposed method has better ability on disturbance rejection.(3)Nonlinear dynamics estimation based funnel control of PMSM system.A disturbance estimator is adopted to estimate the unknown nonlinear dynamics of PMSM.A newly proposed funnel control is applied on the PMSM speed control system.Based on the estimated nonlinear disturbance,a funnel controller is designed,which can guarantee both the transient and steady-state performance.The convergences of the speed tracking error and estimation error are all proved.Simulation results show that the nonlinear dynamics estimation based funnel control can effectively achieve speed tracking and reject nonlinear disturbances.(4)Validation of the proposed speed control strategies based on a PMSM system.Basic principles and implementation process of vector control for PMSM are presented.Based on the framework of vector control,the proposed methods are integrated into the vector control framework.Experiments show that the proposed methods can rapidly track desired trajectory and obtain satisfactory control performance.