Research On Speed Control Of Permanent Magnet Synchronous Motor Based On Disturbance Observation

With the rapid development of power electronics technology,AC speed control and modern control theory,it is a trend that the DC speed control system will be replaced by the AC speed regulation system.Permanent magnet synchronous motor has the advantages of simple structure,small torque ripple,small moment of inertia,wide speed regulation range,good dynamic performance and high control precision,which is widely used in AC speed control system.However,the control system of permanent magnet synchronous motor is a nonlinear,strong coupling and multi variable complex system,coupled with the impact of the disturbances caused by the external environment,the control strategy will directly affect the performance of the motor control.Therefore,the research of control algorithm for permanent magnet synchronous motor is getting more and more attention by domestic and foreign scholars and engineers.To reject the disturbance of permanent magnet synchronous motor speed control system,this paper aims to research on the active anti-interference control method in surface type permanent magnet synchronous motor speed regulating system,Based on the analysis of permanent magnet synchronous motor speed control system,the following main aspects are carried out in this paper:(1)Firstly,this paper introduces the research status of the control strategy for the permanent magnet synchronous motor speed control system,and briefly analyzes several control algorithms used in the current domestic and foreign motor speed control.Then,based on the analysis of the mathematical model of permanent magnet synchronous motor,the vector control scheme of permanent magnet synchronous motor is studied.After introducing the basic principle and the design method of the disturbance observer,a disturbance observer is designed.In this paper the performance of the disturbance observer is verified with sine wave signal and square-wave signal as disturbance signal,which are considered as complex signals.The simulation results show that the observed performance of the disturbance observer is excellent.(2)Considering the nonlinear,strong coupling and multi disturbance in the permanent magnet synchronous motor speed control system,a new method is presented,which is not dependent on the accurate mathematical model.Firstly,the internal disturbance(parameter perturbation,model mismatch,etc.)and the external disturbance(load torque change)are regarded as the total disturbance of the system.Then the disturbance observer is used to estimate the total disturbance of the system,and the effect of the disturbance is eliminated by the feed forward compensation.Considering the great change of the inertia of the motor load in the practical industrial process,a disturbance observer based on inertia identification is proposed to improve the control performance.The simulation results show that the proposed control method is effective.(3)Despite the disturbance observer can effectively suppress the disturbance,which is caused by the differences between the nominal model and the actual model of the system,external interference,as well as internal interference,the noise suppression effect of the existing disturbance observer control system is not ideal,even a lot of researches assumed that the measurement noise of the sensor has negligible effect on the closed loop system.In this paper,an improved disturbance observer is proposed to compensate the output of feedback signal in the system,which is based on the existing disturbance observer,where the external interference and the measurement noise of the sensor can be timely compensated by the controller and output feedback system.The simulation results show that the improved disturbance observer is effective to improve the measurement noise of the sensor.(4)Time delay is inevitable in the speed regulation system for permanent magnet synchronous motor,and the existence of time delay may cause the phase delay and reduce the stability of the closed loop system.Since Smith Predictor can effectively eliminate the impact of the delay,this article puts Smith Predictor technology into the design of the disturbance observer technique,meanwhile,a control method based on the output predictive disturbance observer is proposed.Firstly,the Smith predictor is employed to eliminate the effect of time delay,then the disturbance observer acts on a link without delay,so as to make a timely response to the changes in the system,thereby improving the ability to track the input signal.Simulation results show that the proposed estimator can effectively eliminate the influence of time delay and improve the control performance of the system.