Basics of Stepper Motor Drive - Motor Structure and Working Mechanism

Electromechanical Motors, Actuators, Solenoids and Drivers
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Stepper motors play a key role in numerous automation devices. With high reliability, they enable high-precision positioning in open-loop control and provide high torque at low speeds, making them widely used in industries such as manufacturing, healthcare, 3D printing, and robotics.

Stepper Motor Structure

A stepper motor is primarily composed of a magnetic rotor and stator coils. A common hybrid 2-phase stepper motor features a rotor with two magnetic cups, each typically having 50 teeth with opposite polarities and offset from each other. The stator consists of two coils wound around the rotor. This structural design allows the motor to achieve precise rotational motion through the principle of electromagnetic induction.

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Hybrid Stepper Motor Structure
(a) 8-pole stator. (b) Permanent magnet rotor.(ADI source).

Working Mechanism

When stator coils are energized in sequence, a magnetic field is generated, which interacts with the permanent magnets of the rotor to cause rotation.

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Hybrid Stepper Motor Operation (source: ADI).

The motor achieves precise position control by dividing a full rotation into equally spaced steps. For example, a motor with 200 discrete positions per revolution has a step angle of 1.8° (360° divided by the total number of steps). Current switching alters the magnetic field, guiding the rotor to turn by the step angle without requiring position feedback (open-loop control). This working mechanism gives stepper motors unique advantages in many applications requiring precise position control.

Step Angle = 360° / Total Number of Steps

For more information on how to drive stepper motors, see:

Related Products

  • TMC2240 and TMC5240
    TMC2240 and TMC5240 are intelligent, high performance 2-phase stepper motor driver ICs integrated with motion controllers. The 8-point motion ramp function simplifies the system architecture, allowing users to easily program desired positions and motion profiles.

  • TMC2160 and TMC5160
    TMC2160 and TMC5160 are high power 2-phase stepper motor driver ICs supporting 256 microstep resolution and MicroPlyer microstep interpolation. They optimize driver performance using multiple Trinamic technologies, suitable for a wide range of scenarios from battery-powered systems to high-voltage industrial applications.

  • TMC2300
    TMC2300 is a low voltage driver designed for 2-phase battery-powered stepper motors, featuring 256 microstep resolution and functions such as CoolStep, StealthChop2, StallGuard4, and SpreadCycle.

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