Study On PI Parameter Self Tuning Of Speed Loop In Permanent Magnet Servo System

Permanent magnet synchronous motor(PMSM),as the actuator of high performance and high precision servo control system,has been widely used in many fields.Permanent magnet synchronous servo system usually adopts a nested three-loop(current loop,speed loop and position loop)vector control structure.In order to enable the system to track the given current,speed and position signals quickly and ensure the stability of the system,most of the current servo loop controllers adopt mature PI control mode.In this paper,the PI controller of permanent magnet servo system is studied,and the PI parameters of speed loop are self-tuned.The parameters of the permanent magnet servo system speed loop PI controller are related to the moment of inertia.Therefore,the auto-tuning includes two parts: the moment of inertia identification and the PI parameter self-tuning.Firstly,according to the structure of PMSM and coordinate transformation,the mathematical model of PMSM in each coordinate system is derived.The vector control technology and PMSM vector control architecture are briefly described.Secondly,the inertia identification method is introduced.Several kinds of inertia identification methods are briefly introduced,and the influence of inertia on the control performance of servo system is analyzed.Because offline acceleration and deceleration inertia identification can't do anything for time-varying inertia identification,Landau online inertia identification is introduced.The identification convergence rate and accuracy of Landau on-line identification are greatly affected by the identification gain.Through stability analysis,corresponding identification rate is set up,so that the identification algorithm can balance the convergence rate and the accuracy.The simulation is carried out on MATLAB/Simulink platform.Thirdly,the permanent magnet servo system speed loop PI control parameters are self-tuned.On the basis of tuning PI parameters of speed loop by frequency domain method and engineering tuning method,an evaluation function is designed to evaluate the step response of speed loop,optimize PI parameters of speed loop,and carry out simulation experiments.Finally,a servo experiment platform with TMS320F28377 S as the core control chip is used to verify the feasibility and validity of the proposed algorithm.