Research On Double Sliding Mode Control System Of Permanent Magnet Synchronous Motor

Permanent magnet synchronous motors(PMSM)have the advantages of high torque inertia ratio,high efficiency and high power density,being widely used in civil,aerospace and military fields.Speed closed loop is essential to achieve high performance PMSM control.However,the installation of the speed sensor will increases system cost and reduce reliability and robustness of system,which is also limited by environmental and installation conditions.Therefore,speed sensorless control technology has become one of the most popular research topics in motor control.In this paper,the following researches aim at how to improve the wide speed performance,load capacity,anti-mutation capability and system robustness of the speed sensorless vector control system for permanent magnet synchronous motor.Firstly,this paper introduces the development status of permanent magnet synchronous motor and summarizes the main speed sensorless control strategy.After discussing basic principles of the dynamic mathematics of permanent magnet synchronous motor and vector control,the SVPWM control technique is analyzed.At the same time,the basic principles of sliding mode variable structure control,three characteristics of sliding mode control and the chattering problem of sliding mode variable structure control system are analyzed.Secondly,based on the mathematical model of permanent magnet synchronous motor,the traditional sliding mode observer is discussed.According to arc-tangent,the rotor position and speed are estimated which points out limitations of this method.Therefore,an adaptive sliding mode observer based on phase-locked loop(PLL)is established to estimate the motor speed and rotor position;The saturation function sat(s)is designed as the switching function;And The stability of the observer is analyzed by using the Lyapulov stability theorem,which overcomes the error magnification caused by arc-tangent function and reduces the chattering of observer.In order to expand the low-speed range and enhance the robustness of the system,a sliding mode speed controller based on linear constant velocity approach law is constructed and the stability of the system is determined.The sliding mode speed controller of the integral variable exponential approach law is further derived to analyze the stability of the system,accelerate the approach speed and reduce the chattering on the sliding surface.To sum up,in this part of the paper,a dual-sliding mode vector control system for permanent magnet synchronous motor,which is based on adaptive sliding mode observer and integral variable exponential approaching law sliding mode speed controller,is constructed.Finally,based on MATLAB/Simulink,the simulation system is established,and the simulation analysis is carried out for several aspects such as speed regulation range,load capacity and load resistance mutation.Compared with the traditional sliding mode observer vector control system,the proposed control scheme improves the low-speed load capacity and robustness of the PMSM speed regulation system.The system has strong anti-interference ability,so that it can keep the speed drop within 10%even it operates at very low speed.It also has wide speed range up to 1:600.Furthermore,experimental verification has been carried out on Guwei PTS-1000 physical experiment platform.Simulation and experimental results both verify the correctness of the theoretical analysis It further proves the effectiveness and feasibility of the control strategy studied in this paper.