Research On Telescopic Spindle Speed Control System Based On Permanent Magnet Synchronous Motor

With the increase of telescope aperture and load,the requirement for low-speed transmission capability is also increasing.The traditional worm and gear drive is changed to direct drive by servo motor with large torque,good low-speed performance and small volume.Permanent magnet synchronous motor(PMSM)has become a good choice for direct drive motors because of its large torque,small size,high efficiency and good low speed performance.Permanent magnet synchronous motor(PMSM)control system belongs to the category of AC drive,and the control system is complex.Therefore,it is necessary to study the control system of PMSM and improve the performance of the control system.After studying the driving principle of permanent magnet synchronous motor,the paper chooses the surface mounted permanent magnet synchronous motor and adopts the control mode of vector control to achieve the control characteristics similar to DC motor.The space vector pulse width modulation(SVPWM)method for converting direct current into alternating current is analyzed.On the basis of studying the composition of the current servo hardware system,the traditional PI speed controller and PI current controller are designed by using the information of motor parameters and resonance frequency,and the simulation model is established to obtain the system transfer function and controller parameters.Aiming at the sensitivity of traditional PI controllers to parameter perturbation,a robust sliding mode control method with strong dynamic response and good dynamic response is studied.The controller is used on the speed loop to bring about the sliding mode variable structure switching function.The problem of speed control amount chattering,using a new simple and smooth structure with a switching function of the boundary layer size,so that the chattering amount fluctuates within a small range,thereby reducing the chattering problem caused by the sliding mode.A PI state observer based on Luenberger observer is designed for the uncertain disturbances such as friction torque and wind resistance moment encountered in the operation of the motor.The observer can observe the disturbance torque of the load very well,and then feed forward compensation to the current loop to reduce the fluctuation of the torque.Based on the controller design,the algorithm is transplanted into the DSP program,and the experimental results show that the proposed algorithm is effective.