Research On Servo Control System Of Permanent Magnet Arc Motor For Large Astronomical Telescope

Arc motor is a kind of special motor,the stator of which is spliced by multi segment arc core structure.It has potential application prospects in the driving systems of large-diameter astronomical telescopes,for the reason of easy to process,install,disassemble and maintain.In this paper,the arc motor servo control systems have been studied in the following aspects.This paper summarizes the development and research thesis of arc motor in domestic and overseas.The basic structure,electromechanical conversion principle of arc motor and the fundamental modulation theory are expounded.Meanwhile,the mathematical model of arc motor in rotating coordinate system is constructed.The source of periodic torque disturbance in arc motor servo control system based on PI controller is analyzed.To reject the periodic torque disturbance,the proportional integral quasi resonance(PIQR)controller is designed.And the simulation results from Matlab/Simulink shows the feasibility of this scheme to smooth the speed curve.As for the aperiodic disturbance,an acceleration based disturbance observer(ADOB)which avoids the differentiation of the measured position signal is designed.Thus,the amplification of measurement noise and error at low speed are avoided,meanwhile,the robustness of the system is improved.For the necessary mechanical parameters of the observer,a position signal based model reference adaptive system inertia identification method is designed to avoid the influence of inaccurate speed measurement results.Aiming at the problem of low resolution of encoder,the causes of error and delay in encoder measurement and the shortcomings of common speed measurement algorithms,such as M method and T method,is analyzed.Based on the principle of Kalman filter,a Kalman speed observer(KMO)is designed to extract the speed signal from the original signal of the encoder and improve the speed measurement range.The experiment platform of arc motor servo control system is built,in which the control circuit based on TMSF28335 DSP,sampling and power driving circuit are designed.Meanwhile the control code is programmed based on C language.Experimental results verify the effectiveness of the proposed identification algorithm and the weakening ability of PIQR controller to periodic disturbance.Low speed onload experiments verify the effectiveness of KMO and the improvement of system robustness by ADOB.