Editing Motor controller (section)

== Stepper motor controllers ==
{{Main|Stepper motor}}
[[File:Canon PowerShot S45 - main board - Rohm BD6753KV-91775.jpg|thumb|6-Channel System Lens Driver for Digital Still Cameras: [[Rohm]] BD6753KV]]
A stepper, or stepping, motor is a synchronous, brushless, high pole count, polyphase motor. Control is usually, but not exclusively, done open loop, ''i.e.'', the rotor position is assumed to follow a controlled rotating field. Because of this, precise positioning with steppers is simpler and cheaper than closed loop controls.

Modern stepper controllers drive the motor with much higher voltages than the motor nameplate rated voltage, and limit current through chopping. The usual setup is to have a positioning controller, known as an ''indexer'', sending step and direction pulses to a separate higher voltage drive circuit which is responsible for commutation and current limiting.