Classification and working principle of stepper motors

Release Time：

2025-03-13

A stepper motor is a special type of motor that is controlled by electric pulses to move. It cannot be directly driven by conventional DC or AC power sources, but requires the use of a specialized stepper motor driver.

Classification and working principle of stepper motors
A stepper motor is a special type of motor that is controlled by electric pulses to move. It cannot be directly driven by conventional DC or AC power sources, but requires the use of a specialized stepper motor driver.

A dedicated driving power supply supplies a series of regular electrical pulse signals to the stepper motor. With each input of an electrical pulse, the stepper motor advances one step, and its angular position is proportional to the number of pulses. The speed of the stepper motor is proportional to the pulse frequency, and the speed and direction of rotation are related to the electrification mode of each phase winding.

In non overloaded situations, the speed and stopping position of the stepper motor depend only on the frequency and number of pulses of the pulse signal, and are not affected by load changes. That is, adding a pulse signal to the stepper motor causes it to rotate one step angle.

Stepper motors can achieve speed regulation over a wide range by changing the frequency of input control pulses, and can achieve fast start, reverse, and braking. In addition, stepper motors can be directly controlled using pulse digital signals and converted into angular displacement, making them very suitable for computer control.

A stepper motor moves forward one step with each input pulse, and the angle of the forward step is called the step angle. This type of stepper motion is different from ordinary motors that rotate at a constant speed, so it is called a stepper motor. Due to its working power supply being pulsed voltage, stepper motors are also known as pulse motors.

According to the principle of torque generation, stepper motors can be divided into reactive stepper motors, excitation stepper motors (also divided into electromagnetic and permanent magnet), and hybrid stepper motors.

The stator and rotor of a reactive stepper motor are both convex structures that operate based on the principle of low magnetic resistance. Because the cross axis magnetic resistance of the convex rotor of a stepper motor is different from the direct axis magnetic resistance, the armature reaction magnetic field generates electromagnetic torque according to the principle of low magnetic resistance, thereby driving the rotor to rotate.

The number of teeth on the rotor of a reactive stepper motor can be large, so the step angle can be made very small. Even without a deceleration device, position control can be achieved at low speed and high precision.

The excitation of an excited stepper motor can be permanent magnet or electromagnetic excitation, usually permanent magnet excitation. The rotor of an excited stepper motor has a large driving torque due to its magnetic field. Due to manufacturing processes, the number of rotor magnets cannot be too large, resulting in a relatively large step angle.

Hybrid stepper motors have the advantages of both reactive stepper motors and permanent magnet stepper motors, which can achieve small step angles and high driving torque.