what is the Stepper Motor – Types, Advantages & Applications

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A stepper motor is an electromechanical device it converts electrical power into mechanical power. Also, it is a brushless, synchronous electric motor that can divide a full rotation into an expansive number of steps. The motor’s position can be controlled accurately without any feedback mechanism, as long as the motor is carefully sized to the application. Stepper motors are similar to switched reluctance motors.

stepper motorThe stepper motor uses the theory of operation for magnets to make the motor shaft turn a precise distance when a pulse of electricity is provided. The stator has eight poles, and the rotor has six poles. The rotor will require 24 pulses of electricity to move the 24 steps to make one complete revolution. Another way to say this is that the rotor will move precisely 15° for each pulse of electricity that the motor receives.

Types of Stepper Motor:
There are three main types of stepper motors, they are:

Permanent magnet stepper
Hybrid synchronous stepper
Variable reluctance stepper
Permanent Magnet Stepper Motor: Permanent magnet motors use a permanent magnet (PM) in the rotor and operate on the attraction or repulsion between the rotor PM and the stator electromagnets.

Variable Reluctance Stepper Motor: Variable reluctance (VR) motors have a plain iron rotor and operate based on the principle that minimum reluctance occurs with minimum gap, hence the rotor points are attracted toward the stator magnet poles.

Hybrid Synchronous Stepper Motor: Hybrid stepper motors are named because they use a combination of permanent magnet (PM) and variable reluctance (VR) techniques to achieve maximum power in small package size.

 

Advantages of Stepper Motor:
The rotation angle of the motor is proportional to the input pulse.
The motor has full torque at standstill.
Precise positioning and repeatability of movement since good stepper motors have an accuracy of 3 – 5% of a step and this error is noncumulative from one step to the next.
Excellent response to starting, stopping, and reversing.
Very reliable since there are no contact brushes in the motor. Therefore the life of the motor is simply dependant on the life of the bearing.
The motor’s response to digital input pulses provides open-loop control, making the motor simpler and less costly to control.
It is possible to achieve very low-speed synchronous rotation with a load that is directly coupled to the shaft.
A wide range of rotational speeds can be realized as the speed is proportional to the frequency of the input pulses.
Applications:
Industrial Machines – Stepper motors are used in automotive gauges and machine tooling automated production equipment.
Security – new surveillance products for the security industry.
Medical – Stepper motors are used inside medical scanners, samplers, and also found inside digital dental photography, fluid pumps, respirators, and blood analysis machinery.
Consumer Electronics – Stepper motors in cameras for automatic digital camera focus and zoom functions.
And also have business machines applications, computer peripherals applications.

Operation of Stepper Motor:
Stepper motors operate differently from DC brush motors, which rotate when voltage is applied to their terminals. Stepper motors, on the other hand, effectively have multiple toothed electromagnets arranged around a central gear-shaped piece of iron. The electromagnets are energized by an external control circuit, for example, a microcontroller.

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