Research On PMSM AC Servo System Based On Sliding Mode Control

With the development of high performance microprocessor and permanent magnetic materials,Permanent magnet AC servo system have advantages in its simple structure,high power density,strong overload ability and unlike a brush motor which often needs maintenance.It can present a trend that AC servo system takes the place of DC servo system.The control method of AC servo motor is a hot topic at present.It is necessary to design a reasonable control algorithm to meet the high servo performance of the AC servo system.In this paper,the sliding mode control method of permanent magnet AC servo system is taken as the breakthrough point.The application of traditional sliding mode control and integral sliding mode control method in AC servo motor is analyzed.On this basis,an improved form of sliding mode control strategy is proposed.First of all,this paper introduces the basic structure and operational principle of permanent magnet AC servo motor,and analyses the mathematical model of AC servo motor.Besides,the traditional vector control method and the principle of space vector PWM are introduced,and the simulation platform is analyzed and summarized,and the shortcomings of traditional vector control are analyzed.Then,the sliding mode control method is introduced.Based on the sliding mode control theory,a speed controller based on the traditional sliding mode control and integral sliding mode control is designed,and the stability of the designed controller is proved by the control theory.On the Matlab/Simulink platform,two kinds of servo system model including sliding mode control are set up,and the simulation analysis is carried out.The simulation results show that although the sliding mode control method improves the servo performance of servo system,it still has some shortcomings in response performance,global sliding mode characteristics and immunity.Finally,through the analysis of the comparison of several servo control methods,this paper proposed a global sliding mode controller with nonlinear integral based on the load observer combined with the sliding mode control theory.The simulation results show that the sliding mode controller has faster response speed,no overshoot,and has the characteristics of global sliding mode and a certain immunity.In addition,an experimental platform is built to verify the control strategy proposed in this paper.The experimental results show that the controller can make the system have better servo performance,which proves the feasibility and effectiveness of the designed controller.