Electric stepper motors

A stepper motor is a brushless synchronous electric motor that converts electrical impulses into mechanical rotation of the motor shaft in a number of steps. Each step corresponds to a precise rotation of the motor, allowing very precise control of position, speed and acceleration. There are three main types of stepper motor: the variable reluctance motor, the permanent magnet motor and the hybrid motor, which is a combination of the two previous technologies.

Stator

A fixed part of the motor, the stator consists of several coils of wire wound around poles. The stator creates a magnetic field when a current flows through it.

Rotor

The rotor is the moving part of the motor. The rotor is generally made up of permanent magnets or ferromagnetic poles. The rotor follows the magnetic fields produced by the stator.

Windings

The wire coils on the stator are activated in sequence to create magnetic fields.

Excitation of the coils

The stepper motor works by sequentially energising the stator coils. Each activation moves the rotor by a precise ‘step’.

Switching sequence

The controller sends electrical pulses to the coils in a specific sequence. This switching sequence determines the direction and distance of movement.

Angular movement

With each electrical pulse received, the stepper motor rotor moves through a fixed angle. The total number of pulses determines the final position of the rotor.

Stepper motors are used in a variety of applications where precise control of position and speed is crucial.