Unipolar Stepper Motor

Unipolar stepper motors use center-tapped phase windings. Each phase is split into two half-windings, and the drive energizes one half at a time to produce step motion. With this arrangement, phase polarity is determined by selecting which half-winding is energized rather than reversing current through the full coil.

In a standard unipolar drive, current reversal is not required, so the output stage is often implemented with low-side switches or transistor array drivers (for example, ULN2003A-class devices) when the motor current and voltage ratings allow. Driver selection should be based on the motor’s phase current, supply voltage, and the intended duty cycle.

With only part of the winding energized at a time, available torque depends on winding use, current setting, and the motor’s magnetic design. Unipolar stepper motors are commonly used in equipment that uses center-tap wiring and switching interfaces, with final performance verified against the datasheet for the specific model.