Stepper Motors: Basic Configuration

Rotor: Permanent magnet mounted to the motor shaft
Stator: Two windings (coils, phases), powered by a driver electronics.

No brushes needed.

When windings are powered, they generate a magnetic field.
It is guided by stator claws (claw pole motor design) or teeth
of laminated iron (hybrid stepper motor design).

Stator north/south poles and rotor permanent magnet poles interact.
They attract each other, the rotor is moved to a new position.

By switching winding currents on/off and in both directions, a sequence of steps is being executed.

Picture shows this basic configuration, but simplified for a 2 pole permanent magnet.
stepper motors 

 

Clock (step frequency) and speed


Typical step frequencies for JE claw pole stepper motors are in the range 50 …500 Hz.
Frequency can be higher if a Chopper driver circuitry is applied (see section below).

Speed (in rpm) is:
   

 

Example:
Step angle 15° and step frequency (clock) 200 Hz à Speed = 500 rpm