Research On Vector Control Technology For Hybrid Stepper Motor

Stepper motors are widely used in 3D printers,CNC machines,robots,and other electromechanical systems due to their simple control method and low cost.With the changes in market demand,traditional open-loop control and subdivision control technologies are difficult to meet the requirements.In recent years,research on stepper motor vector control technology has received widespread attention.Compared to permanent magnet synchronous motors,the nonlinearity of hybrid stepper motors is more obvious,and the influence of reluctance torque cannot be ignored.Common stepper motor vector control systems do not consider this factor,and their SVPWM algorithm has low voltage utilization,which affects the dynamic performance of the motor.This article studies these two key issues.Based on this,in order to reduce system manufacturing costs,Further research was conducted on two vector control technologies for position free stepper motors,and their characteristics were compared and verified.The main specific work content is as follows:Firstly,the structure and operating principle of a two-phase hybrid stepper motor were analyzed.Based on the magnetic network model,the inductance of the motor winding was derived,and the voltage and current equations of the motor winding were obtained.The electromagnetic torque equation of the motor was obtained through magnetic energy sharing.A mathematical model using synchronous rotating coordinate system was derived via coordinate transformation,and simulation models of the motor were established in Simulink under both stationary coordinate system and synchronous rotating coordinate system.Secondly,for the inverter algorithm of two-phase hybrid stepper motors,a four nonzero vector SVPWM algorithm based on the traditional dual H-bridge basic driving circuit is first presented.Based on this,all non-zero vectors under the dual H-bridge are considered,and an eight non-zero vector SVPWM algorithm is designed.For the sake of simplifying hardware,a three-phase inverter based two-phase hybrid stepper motor SVPWM algorithm is proposed using three bridge arms.The above three SVPWM algorithms are compared,the voltage utilization rate of the eight non zero vector SVPWM algorithm is the highest,so this paper uses it as the inverter algorithm for the vector control system of the stepper motor.Then,based on the principle of subdivision control,simulation models are established in both stationary and synchronous rotating reference frames.Develop a vector control model using the mathematical model of the motor as the basis.,and refer to the expression of the reluctance torque to compensate for the q-axis current,generating electromagnetic torque that is equal in magnitude and opposite in direction to counteract the reluctance torque.Comparing the simulation results of the two control methods,vector control technology can dynamically adjust the current size,making the motor run more smoothly,and the error during operation is about 8 subdivision step angles in subdivision control.Finally,position free control is introduced into the two-phase hybrid stepper motor control system,and the rotor position and speed of the motor are observed through model reference adaptation and pulse high-frequency injection.The simulation results show that the pulse high-frequency injection method has smaller high-frequency harmonics and higher accuracy in estimating the rotor position and speed.