Research On AC Servo System Of Tuning Strategy Of Control Parameters And External Load Torque Observer Design And Compensation

AC servo has many advantages such as lower noises, higher credibility, moremoment exporting, higher efficiency and smaller weight. So it has been used more andmore widely.The control parameters of AC servo system and the performance are closelyrelated, in order to obtain satisfactory AC servo system performance, the settingparameters of the AC servo system must be tuned. Therefore, it is important andsignificant to study the tuning method of AC servo system control parameters toimprove the efficiency and performance of AC servo system.In addition to the effect of the control parameters, various uncertainties can alsoaffect the performance of AC servo system. The change in the load torque also has agreat impact on system performance. State observer is insensitive to the internalsystem parameters, and has advantages of good robustness to external disturbance andfast dynamic response etc. So, it has been widely applied in AC servo system control.Firstly, analyzes the permanent magnet synchronous motor’s mathematical modelat different coordinates and the conversion among them, then, builds the synchronousmotor’s model for vector control, finally, using the simulation to verify thecorrectness of the model.Secondly, the transfer of various components of the AC servo system wasanalyzed; corresponding mathematical models of the three controlling loop frominternal to external namely current loop, velocity loop, and position loop w ereestablished respectively according to the PMSM structure of various sectors of the ACservo system; the process of control parameter tuning was analyzed by using theestablished AC servo system’s mathematical model and theoretical basis for the studyof control parameters tuning was obtained.Thirdly, according to the mathematical equation of the permanent magnetsynchronous motor, full-order and reduced-order load torque observer are separatelyproposed, and according to the simulation results, the comparison between thefull-order and reduced-order load torque observer is given. The consequence showsthat the reduced-order load torque observer has the advantage of easier design, lesstuning parameters, the more correct estimation, and the load torque compensationstrategy based on the reduced-order observer has good robustness to load torque disturbance.Finally, the experimental AC servo system was built. By experimentalverification, it can come to a conclusion that after control parameter tuning, the ACservo system has good accuracy, stability and fast response ability. The observer canmake fast response to follow the change of load torque, the torque compensationbased on the reduced-order observer compensates the load torque well, improves theperformance of the AC servo system.