Research On Low-speed Disturbance Rejection Technology Of Permanent Magnet Synchronous Motor In Large-aperture Astronomical Telescopes

The permanent magnet synchronous motor(PMSM)is widely used in the tracking rack drive of large-diameter astronomical telescopes due to its simple structure,high efficiency and high power density.The difficulty of PMSM low-speed control lies in disturbance rejection.There are periodic and aperiodic disturbances in the control system,resulting in speed fluctuation and poor control.Therefore,the research on disturbance rejection of PMSM in low speed operation has high theoretical research value and potential engineering application prospects.The thesis summarizes state of the art and development trend of PMSM for large-aperture astronomical telescopes and the research status of disturbance rejection in Low-speed Control systems.A PMSM control system considering disturbances is established,after analyzing the sources,action forms and effects of aperiodic and periodic disturbances.In the thesis,a PMSM low-speed active disturbance rejection control(ADRC)system is studied and designed.The error differential feedback term is added to the extended state observer(ESO)in ADRC,which improves the observation ability of disturbance.A new state error feedback control law is proposed.A high pass filter(HPF)is added to the linear feedback,effectively improves the problem that the traditional ADRC has weak ability to reject disturbances in the mid-frequency band.The moment of inertia of the system is identified and updated to the parameter design of ADRC by model reference adaptive controller(MRAC).The thesis builds a simulation model and designs the hardware circuit of the control system as well as the control program.Then the thesis verifies the system through simulation and physical experiments.The dynamic and steady-state performance of the system is compared and analyzed in different parameter,then the design principles are summarized.Three controllers in the speed loop,PI,ADRC and ADRC+HPF are compared.The results show that ADRC+HPF improves ADRC’s ability to reject periodic disturbances,and the system steady-state performance is better.MRAC improves the dynamic performance of ADRC.Therefore,the PMSM low-speed control strategy proposed in the thesis can greatly improve the disturbance rejection ability of the system,enhance the system robustness,and realize the low-speed stable operation of the PMSM.