| Because of its high precision in positioning, stepping motor is widely used in office and factory automation applications. Among various types of stepping motor, hybrid stepping motor is the most commonly used since it has the advantages of higher efficiency and toque capability over the other stepping motors. The hybrid stepping motor is usually used as the actuator in the open-loop position servo system and the low-speed open-loop speed servo system. This type of servo system is simple and not expensive. But its shortcoming is also obvious: noisy, ripple of torque and speed, resonating in some frequency domain and even the worst losing steps.It is well known that micro-stepping reduces resonance behavior of stepping motors since the rotor moves in a sequence of very small steps. Hybrid stepping motor, which is also known as a synchronous inductor motor, was originally designed to operate as a low-speed synchronous motor. Theoretically, the hybrid stepping motor can be considered as a multiple synchronous motor. The advanced control strategies widely applied such as Field Oriented Control (FOC) in synchronous inductor motor can also be used in hybrid stepping motor.In this paper the principle of the three-phase hybrid stepping motor is analyzed, the prototype of the motor is set up, and its mechanism of torque is analyzed. The digital PID controller and Space Vector Pulse Width Modulation (SVPWM) are the most important contents in the digital control system. A digital PID controller with anti-windup correction and SVPWM technique are presented in detail.Digital control system of hybrid stepping motor based on TMS320LF2403A is built. Experiment is carried out, and the results validate the feasibility of this project.
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