High-speed And Stable Operation Control Of Permanent Magnet Synchronous Motor Based On Sliding Mode Variable Structure

Permanent magnet synchronous motors(PMSM)have attracted widespread attention due to their wide speed range,high efficiency,high power density and large torque.Flux-weakening control is the key technology to realize its wide-range speed operation.Permanent magnet synchronous motors have non-linear characteristics of multiple variables,strong coupling,and variable parameters.Traditional PI control can play a good control effect for linear control systems,but it’s difficult to achieve high-performance current regulation of PMSM.This paper aims to improve the control performance of PMSM and achieve wide-range speed regulation.By combining sliding mode variable structure control and flux-weakening control strategy,a sliding mode speed controller is designed,and a flux-weakening control system for PMSM based on sliding mode variable structure control is constructed,which improves the robustness and immunity of the control system.First of all,this paper introduces the necessity of using flux-weakening control for permanent magnet synchronous motors.Based on a review of the fixed-q-axis voltage single current regulation algorithm of PMSM,a single current regulator based on virtual impedance is designed to solve the defect that the ambiguous reference value of the quadrature axis voltage in the application of the single current regulator,and the operating efficiency and torque output capacity of the PMSM can be taken into account at the same time.The correctness and effectiveness of the algorithm are verified through computer simulation and experiments.Secondly,the basic theory of sliding mode variable structure control is introduced,and the speed controller of the PMSM control system using the i_d=0 control strategy is designed using the exponential approach law.In order to improve the performance of the controller,the square term of the state variable is introduced on the basis of the original exponential approach law and a new approach law is proposed.Simulation and experiments are designed.to verified the feasibility and superiority of the new approach law speed controller.Finally,a speed controller for improving flux-weakening control is designed which combining sliding mode variable structure control with the flux-weakening control strategy based on virtual impedance,and a flux-weakening control method based on sliding mode variable structure for PMSM is proposed.The PMSM control system constructed by this control method not only achieves high-speed and wide-range stable operation,but also improves the robustness of the flux-weakening control.The robustness and immunity of the method against load disturbance and bus disturbance are verified in simulation and experiments.