Stepper Motor Control

Stepper Motor Control

Stepper motors are controlled electronically by pulses of DC. Stator poles are arranged in groups. The sequence used to energize these poles determines the direction of rotation. Although  used mainly in positioning applications, the speed at which pulses are supplied determines the speed of rotation.

Fig. 40 The sequence used determines the movement of the stepper motor

Open Loop Techniques

Stepper motors are usually controlled using an open loop technique.

Fig. 41 Open loop control of a stepper motor

Closed Loop Techniques

If the stepper motor is prone to losing steps then an open loop scheme will not position the motor correctly. In this case a sensor such as an encoder may be used to detect position and improve position control.

Fig. 42 Closed loop control of the stepper motor