Research On Torque Ripple Suppression Strategy Of Hybrid Stepper Motor Based On Active Disturbance Rejection Control

With the rapid development of technology and industrial sectors in modern society and the increasing demand for machine tools,robots,aerospace and industrial assembly line control systems,the performance requirements of hybrid stepper motor control systems and the accuracy requirements of Numerical control platforms are increasing.The stepper motor has the problem of vibration caused by large torque ripple in operation.In this thesis,two control methods are proposed to solve the problem of large output torque ripple of the hybrid stepping motor.In order to solve the problem of large output torque ripple of hybrid stepper motor,two methods of auto-disturbance rejection vector control and adaptive continuouscurrent ratio mode control are proposed based on state observation feedback optimization.The main work of this paper can be summarized in the following four aspects.Ⅰ.Mechanism analysis and modeling of hybrid stepper motor torque rippleAccording to the structure and working principle of the hybrid stepping motor,its mathematical model is established.Through analyzing the resonance of groove torque ripple and electromagnetic torque ripple,the main factors of torque ripple in the process of motor operation are further obtained.It is found that the main influencing factors of the motor torque fluctuation are the interference amount and the non-sinusoidal component in the electromagnetic torque and the tooth groove torque.Ⅱ.Active disturbance rejection vector control based on state observation feedback optimizationThe basic principle of ADRC(Active disturbance rejection control)is analyzed.The traditional ADRC has the problem of tracking delay,and the torque ripple suppression in the operation of the hybrid stepping motor is limited.In this thesis,an improvement is proposed.The difference between the given and feedback of the system and its differentiation are done as the output x1(t)and x2(t)of the tracking-differentiator link;the actual speed is used to replace the output z1 of the extended state observer,and the state quantity observation calculation process is used to estimate the perturbation term z3.The improved algorithm reduces the calculation burden of the controller,thus reducing the delay,and can effectively suppress the torque ripple in the operation of hybrid stepper motor.Ⅲ.Adaptive relay ratio control method for hybrid stepper motorFor the H-bridge drive circuit of stepper motor,the traditional mixed-current mode of slow and fast decay has the problem of narrow application range and cannot run efficiently in all working conditions.Pulsation cannot be well suppressed under the scenarios of motor speed,operating voltage,current or temperature change leading to motor inductance change.In order to solve these problems,a control method of adaptive relapse-ratio hybrid stepper motor is proposed.The difference between the target subdivision current value output by the ring distributor and the measured current value feedback is obtained,and then the percentage of fast current is determined in real time by the adaptive continuous-current ratio controller and finite state machine,so as to adapt to the motor control system under different working conditions and suppress the torque ripple in the motor operation.IV.Simulation and experimental verificationThe control system is built based on MATLAB/Simulink simulation software.Firstly,the output torque ripple of hybrid stepper motor is compared and analyzed when the load is 0.1N·m,0.2N·m,0.3N·m and the supply voltage is 12V,24V and 36V respectively in the active disturbance rejection vector control optimized by state observation feedback.Secondly,the phase current and output torque ripple of the motor under the traditional mixed and the adaptive continuous-current ratio mode are compared and analyzed.Finally,the software and hardware were designed,the experimental platform was built,and the output torque ripple of the motor was analyzed in different working conditions,and the two control methods were compared.To sum up,in view of the vibration problems existing in the operation of hybrid stepper motor,ADRC and adaptive continuation ratio control are proposed in this paper.The simulation and experimental results show that the ADRC method based on state observation feedback can reduce the torque ripple of the motor by about 25%,and the torque fluctuation range of adaptive continuous current ratio mode is reduced by about 40%.Both control methods can effectively reduce the torque ripple of hybrid stepper motor,and the latter has better suppression effect than the former.