Stepper Motor is an electromechanical device that converts electrical energy into mechanical energy. It is an electromagnet that can rotate freely. The original model dates back from 1830 to 1860. At the beginning of 1870, attempts to control were applied to the electrode transport mechanism of the hydrogen arc lamp. This is considered to be an early primary stepper motor. In the early twentieth century, stepper motors were widely used in telephone automatic switches. The invention of transistors in the late 1950s was gradually applied to stepper motors, making digital control easier. In the late 1980s, cheap microcomputers appeared in a multi-functional manner, and the control methods of stepper motors were more flexible.
The big difference between stepper motor and general motor is that it receives digital control signal, electrical pulse signal, and converts to corresponding angular displacement or linear displacement. It is an actuator to complete digital mode conversion. The angular displacement of the stepper motor is strictly proportional to the number of pulses input, and synchronizes with the pulse in time. Therefore, as long as the number of pulses, frequency and phase sequence of motor windings are controlled, the required angle, speed and direction can be obtained.
Types of Stepper Motor
There are three main types of stepper motors: variable reluctance stepper motor, permanent magnet stepper motor, and hybrid stepper motor. Variable reluctance (VR) stepper motor is combined with soft iron, non-magnetic, tooth-shaped rotor and electromagnetic stator. Permanent magnet (PM) stepper motor is made of permanent magnet material, and the number of poles of the rotor is the same as the number of poles of the stator. Hybrid (HB) stepper motor combines the advantages of VR stepper motor and PM stepper motor. Its stator has multi-phase windings, permanent magnet material is used on the rotor, and there are many small teeth on the rotor and stator to improve the step accuracy.
The advantages of Stepper Motor
1)The rotation angle of the motor is directly proportional to the input pulse.
2)The stepper motor is full torque at rest.
3)Very reliable, because the motor has no contact with the brush. Therefore, the life of the motor depends entirely on the life of the bearing.
4)Accurate positioning and motion repeatability
5)Good response to starting, stopping and reversing.
6)The motor provides open-loop control of the digital input pulse response, making the motor simpler and less costly to control.
7)Very low speed synchronous rotation is achieved by a load directly coupled to the shaft.
8)Since the rotational speed is proportional to the frequency of the input pulse, a wide range of rotational speed can be achieved.
Applications of Stepper Motor
Industrial Machines: stepper motor is used in automotive gauges and machine tooling automated production equipment.
Security: new monitoring products for the security industry.
Medical: stepper motor is used in medical scanners, samplers, and in digital dental photography, fluid pumps, respirators, and blood analysis machines.
Consumer Electronics: stepper motor is used on cameras for automatic digital focus and zoom functions.
Operation of Stepper Motor 
Stepper motor works differently than DC brush motors, which can be rotated when voltage is applied to their terminals. On the other hand, stepper motor actually has a plurality of toothed electromagnets arranged in a central gear-shaped iron piece. The electromagnet is powered by an external control circuit, such as a microcontroller. A servo motor is generally composed of four parts: a DC motor, a transmission, a control circuit, and a position sensor (usually a potentiometer). A stepper motor is essentially a servo motor that uses a different motor approach. When the servo motor uses a continuously rotating DC motor and an integrated controller circuit, the stepper motor uses a plurality of toothed electromagnets arranged around the center gear to determine the position.