A stepping motor or a step motor or a stepper motor is referred to as a brushless DC electric motor that partitions a full pivot into various equivalent steps. The position of the motor can be made to hold and move at one of these steps without any rotary encoder for feedback.

Basics of operation

There is a continuous rotation of brushed DC motors whenever a DC voltage is given across their terminals. The stepper motor is popular by its functionality of changing input pulses (square wave pulses) into an accurately characterized augmentation in the pole position. Each pulse makes the shaft to move by a fixed angle.

Stepper motors come with multiple "toothed" electromagnets that are placed around a central gear formed in the shape of an iron. The electromagnets are made to energize by a microcontroller as well as an external driver circuit. To carry out the turning motion in the motor shaft, firstly, power is supplied to the electromagnet which attracts the teeth gear magnetically. When the teeth gear lines up with the first electromagnet, they are somewhat balanced from the succeeding electromagnet. Now as the following electromagnet is switched ON and the previous one is switched OFF, the gear turns marginally to line up with the following one. This process is then repeated and each of these rotation is known as "step".

The electromagnets’ circular arrangement is split into groups, each group is known as a phase, and every group comes with an equal number of electromagnets. The number of groups is selected by the creator of that particular stepper motor. Each group's electromagnet is interleaved with other group's electromagnets to establish a uniform pattern of arrangement. Let’s understand it with an example. Assume that the stepper motor consists of 2 groups A and B. Along with that it has 10 electromagnets. The grouping will be like ABABABABAB.

Electromagnets that are within a particular group are all energized together. As a consequence, the stepper motor with more phases regularly has more wires to operate the motor.

Advantages

• Low speed and high torque at startup.
• Ease for control accomplished.
• Construction is simple.
• Ruggedness
• It can be operated in an open-loop control system.
• Low maintenance.
• Will surely wok in any kind of environment.
• Less chance to slip or stall.
• It can be utilized in robotics.
• The input pulse is proportionate to the rotational angle.
• Highly reliable.
• Full torque at standstill.
• It provides a quite good response to reversing / stopping / starting.
• As there are no contact brushes in the motor, they are very much reliable. Thus the motor’s life is dependent completely on bearing’s life.

Applications

Stepper motors are commonly used in flatbed scanners, compact disc drives, computer printers, slot machines, image scanner, intelligent lighting, CNC machines, camera lens as well as in 3D printers.

Hope you liked the article on stepper motors. Brands that manufacture them are Applied Motion, CUI and Pololu. Make sure to follow the links as provided.

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