Learn About Stepper Motors

Last modified by Microchip on 2023/11/10 11:17

A stepper motor is a DC motor that moves in discrete steps. The coils are organized into phases. When the phases are energized in sequence the motor will rotate in precise increments.
Inside a Stepper Motor

Types of Stepper Motors

Permenent Magnet Stepper Motor

The rotor is permanently magnetized. A voltage is applied in sequential order to the stator windings. The magnetized stator coils then attract the rotor.

Permanent Magnet Stepper Motor Diagram

Variable Reluctance Stepper Motor

This type of motor uses a non-magnetized iron rotor with 'teeth' that are offset from the stator. As the stator coils are activated the rotor moves.

Variable Reluctance Stepper Motor Diagram

Hybrid Synchronous Stepper Motor

This motor type is a combination of the two previous designs. The rotor has magnetized teeth whose polarities are offset from each other. Two stator windings are activated with different polarities to move the rotor. This type of motor can offer higher torque and more precise stepping.

Hybrid Synchronous Stepper Motor Diagram

Controlling a Stepper Motor

Open loop control is used on stepper motors. Utilizing a synchronized series of outputs stepper motors can be moved by single steps, half steps, micro-steps

Single Step control

Activating one stator coil at a time, or a pair of adjacent coils a stepper motor will cause the motor to rotate 1/4 of an electrical cycle. 


Activating 2 stator coils at a phase of 90 degrees will cause the rotor to take 8 half-steps for each electrical rotation.


Outputting a sinusoidal signal on adjacent stator coils, with the same phase as a half step, will cause to rotor to move in what is referred to as micro-steps.

Microstep Sinusoidal Signals

Advantages and Disadvantages of Stepper Motors


  • Precise positioning
  • High torque at low speed.
  • Ideally suited for high-precision applications such as printers and CNC.


  • Low torque at high speed
  • No inherent feedback, external circuits are required to gain position feedback.
  • Electrically inefficient

Learn More