Research On Microstep Drive System Of Stepper Motor

This paper is based on the research of two-phase hybrid stepper motor drive circuit for a commercial space solar panel drive device.Stepper motor is generally used as driving source for solar panel driving devices.Stepper motor has the advantages of no cumulative error,no brush discharge,high positioning accuracy,high holding torque,small size and low weight,and does not need to use complex closed-loop position and rate control.In order to meet the stability requirements of micro-satellite platform,the whole step and half step control system of micro-perturbation torque stepper motor combined with harmonic reducer has become the mainstream driving scheme.With the improvement of payload accuracy,the superstable satellite platform requires the solar panel drive device to reduce the disturbance amount,and then requires the drive source to reduce the positioning torque and improve the rate stability.Therefore,this paper takes two-phase hybrid stepper motor as the controlled object,and conducts related research on speed control and microstep drive control of stepper motor.The main research contents are as follows:First of all,aiming at the two-phase hybrid stepping motor as the controlled object,the basic structure and working principle are analyzed,the mathematical model is derived,and the simulation model of the stepping motor based on MATLAB/Simulink environment is built and verified,which lays a solid foundation for the theoretical research and verification in the following paper.Secondly,aiming at the micro-vibration control requirements of variable speed in the working mode of solar panel drive device,the trapezoidal torquefrequency characteristic curve of stepper motor is analyzed,and an improved speed control method based on parabolic operation curve is proposed.The mathematical model of the given curve of parabolic speed is derived,and the generation module of the given pulse of parabolic speed is established,and the three operation curves are compared.The results show that the proposed improved parabolic curve control method can effectively improve the speed control performance,speed response and stability of the stepper motor.Then,aiming at the micro-step drive control of the super-stable satellite platform,three micro-step drive control methods are compared and studied,an improved micro-step drive method based on current tracking PWM and H-bridge drive circuit is proposed,and a current waveform selection method based on the approximate method is designed.The stepper motor drive source can run smoothly in acceleration and deceleration process,reduce the positioning torque,and significantly improve the motor speed control precision and positioning control precision.Finally,based on STM32F407 microcontroller and DRV8825 motor drive chip,the hardware circuit of stepper motor drive is designed.Based on Keil5 software environment,the program is written,and the experimental test platform of stepper motor is built.The whole step and multiple subdivision microstep drive algorithms are designed and verified,and the winding current waveform of the stepper motor is compared.Experimental results show that the proposed microstep drive method achieves high stability and high precision drive control of stepper motor.