A stepper motor is an electromechanical device that converts electrical pulse signals into precise mechanical rotational movement. It rotates in fixed angular increments called “steps”, which enables accurate position and speed control without requiring a feedback system.

How a stepper motor works
A stepper motor mainly consists of a stator and a rotor. The stator contains multiple electromagnetic coils, while the rotor is usually made of permanent magnets or soft magnetic materials.

When electrical pulses are applied to the stator windings in a specific sequence, the process works as follows: the stator coils generate a rotating magnetic field, which attracts or repels the rotor. As a result, the rotor moves a fixed angle (one step). Continuous pulse signals make the rotor rotate step by step, and the total rotation angle is directly proportional to the number of input pulses.

Basic operating principle
Electrical pulse signal → Motor driver controls coil energizing → Magnetic field generated in stator → Rotor moves step by step → Precise rotational motion output

Key characteristics of stepper motors
Precise positioning – accurate control of rotation angle
Open-loop control – no encoder required in many applications
High holding torque – strong torque at low speed
Excellent repeatability – consistent step accuracy
Simple control system – easy integration with controllers
Low-speed stability – smooth operation at low RPM

Common step angles
Typical step angles include 1.8° per step (200 steps/revolution) and 0.9° per step (400 steps/revolution). Smaller step angles provide higher positioning accuracy and smoother motion control.

Types of stepper motors
Permanent Magnet (PM) stepper motor uses a permanent magnet rotor and provides good low-speed torque performance. Variable Reluctance (VR) stepper motor uses a soft iron rotor and operates based on magnetic reluctance changes. Hybrid stepper motor combines the advantages of both PM and VR types, offering high precision and high torque, and is the most commonly used type in industrial automation.

Applications of stepper motors
Stepper motors are widely used in CNC machines, 3D printers, robotics, medical equipment, packaging machinery, AGV/AMR systems, textile machinery, and semiconductor equipment.

Advantages of stepper motors
High positioning accuracy, fast start and stop response, excellent low-speed performance, cost-effective motion control solution, and reliable durable structure.

Disadvantages of stepper motors
Torque decreases at high speed, possible resonance and vibration, lower efficiency compared with servo motors, and potential step loss under overload conditions.