Whirlpool WSE 2930 W Manual page 52

Functional characteristics
Dispenser stepper motor
A stepper motor (or step motor) is a brushless, synchronous electric motor that can divide a full rotation
into a large number of steps. The motor's position can be controlled precisely, without any feedback
mechanism.
Stepper motor characteristics:
Stepper motors operate differently from normal DC motors, which rotate when voltage is applied to their
terminals. 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 micro controller. To make the motor shaft turn, first one electromagnet is given power, which makes
the gear's teeth magnetically attracted to the electromagnet's teeth. When the gear's teeth are thus aligned to
the first electromagnet, they are slightly offset from the next electromagnet. So when the next electromagnet
is turned on and the first is turned off, the gear rotates slightly to align with the next one, and from there the
process is repeated. Each of those slight rotations is called a "step," with an integral (complete number)
number of steps making a full rotation. In that way, the motor can be turned by a precise angle.