Research On Position Control Of 3-phase Hybrid Stepper Motor With High Dynamic Response

Stepper motor,as a typical digital actuator,can achieve high positioning accuracy with simple open-loop control,and it is widely used in CNC machines,robots and PC automation.Hybrid stepper motor,with the advantage of small step angle of reactive stepper motor and high power density of permanent magnet stepper motor,has occupied the market with absolute advantages since its birth.It has basically replaced the reactive stepper motor and permanent stepper motor.The traditional hybrid stepper motor driver uses simple open-loop control,which is easy to lose step,overshoot and even block rotation in some occasions with large load disturbance and frequent starting and positive and negative rotation,which seriously reduces the reliability of the control system and cannot meet the requirements of modern high-precision and high-speed servo control.In recent years,the closed-loop control of hybrid stepping motor with position feedback has been widely concerned because it can theoretically avoid the risk of losing step or blocking rotation.On the other hand,the hybrid stepping motor has a mature product line,and its high cost performance makes it more competitive in the low-end servo occasions.However,compared with the permanent magnet synchronous motor,hybrid stepper motor runs at a lower maximum speed,which limits its application in servo with high dynamic response requirements.Therefore,it is of great practical significance to select the appropriate driving strategy and design the corresponding control algorithm to realize the high dynamic performance closed-loop control of the hybrid stepper motor.This article briefly introduces the basic structure and working principle of three-phase hybrid stepper motor,and derives the self-inductance,mutual inductance and the basic equations by building up the equivalent magnetic network.The mathematical model under rotating coordinate system is derived by using Park transformation.Then based on the model,the vector control of three-phase hybrid stepper motor is discussed in detail,and an improved realization of SVPWM is given which aims at the shortcomings of the traditional SVPWM algorithm.Some special problems are analyzed for the motor with delta connection winding.To improve the dynamic performance of hybrid stepper motor,a flux weakening control based on negative direct-axis current compensation is given by analyzing the control requirements.This article also designs the passivity-based positioning controller base on the Euler-Lagrange error equation.Finally,the three-phase hybrid stepping motor closed-loop control simulation system is built in the MATLAB/SIMULINK environment,and the experimental platform including the driver and upper computer software are designed to complete the model and algorithm verification.The simulation and experimental results prove the effectiveness and correctness of the proposed algorithm.