White Papers

Closed loop control of stepper motors without position sensor

Print page

Email page

This paper presents a patent-pending method to operate stepper motors in closed loop position without position sensors, boosting stepper-motor performance into the range of servomotor performance while maintaining the inherent simplicity of the conventional stepper motor drive system.

By Rich Dirker, Agile Systems

STEPPER MOTOR drive systems appeal to a wide variety of position and motion control applications, because of their inherent control simplicity and lower cost versus servo-system alternatives. The performance of conventional stepper motor drive systems is limited, excluding them from applications requiring high speeds, high acceleration rates and smooth motion. They are also prone to excite mechanical resonance, stall easily and emit discernible audible noise. Over the years added stall detection and electronic resonance damping features have provided partial improvements.

Over the years efforts have been undertaken to transform stepper-motor systems into pseudo servos, by adding feedback based closed loop control or implementing means of indirect stall detection and resonance damping. However, the proposed methods either increase system complexity by adding feedback devices or overcome some of the typical stepper motor disadvantages only partially by adding stall detection and resonance damping algorithms. The method presented here overcomes all conventional stepper-motor drawbacks without adding feedback components and thus maintaining the simplicity of conventional, open loop stepper motor drive systems.

File Size: 60 KB
File Type: PDF

This content is for members only. Please use the login or register link below to access this white paper.

Login or Register Now