A stepper motor is a brushless, synchronous electric motor that can divide a full rotation into a large number of steps. Stepper motors operate differently from DC brush motors, which rotate when voltage is applied to their terminals. To rotate, each step motor needed from an external control circuit, such as a microcontroller.
Stepper motors, on the other hand, effectively have multiple “toothed” electromagnets arranged around a central gear-shaped piece of iron. The electromagnets are energized by an external control circuit, such as a microcontroller.
There are two basic winding arrangements for the electromagnetic coils in a two-phase stepper motor: bipolar and unipolar. A unipolar stepper motor has two coils per phase, one for each direction of the magnetic field. Bipolar motors have a single winding per phase. The current in a winding needs to be reversed in order to reverse a magnetic pole, so the driving circuit must be more complicated. There are two leads per phase; none are common.

All automotive stepping motors are bipolar type.

FEATURES