stepper motor explanation

Stepper Motor Explanation

Today we’ll discuss regarding stepper motor, its operating, types, advantages, disadvantages with it practical space.

In easy words, it’s a mix of DC motor with natural philosophy technology that permits the motor to rotate and stop at mere angle.

It is principally employed in artificial intelligence wherever move the arm of robots at mere angle and hold there for a few time and acquire back come back once it.

This is a brushless mechanical device that is employed to convert the series of electrical pulses applied at their excitation winding into exactly outlined step by step the mechanical shaft rotation.

In others words, the stepper motor is associate mechanical device that converts electric power into mechanical power.

It is a particular type of DC motor that does not rotate continuously, but a full rotation is divided into the number of equal steps.

It works on the principle that, the theory of operation for magnets to make the shaft turn the precise distance when a pulse of electricity is provided.

In a stepper motor, number of input as pulses given to the motor decides the steps angle and hence the position of the shaft is controlled by controlling the number of pulses.

These distinctive options that’s totally different from the servo motor build the stepper motor to be appropriate for open loop system whereby the precise position of the

shaft is maintained with the exact number of the pulses without using a feedback sensor.

If the steps angle is smaller, then the greater will be the number of the step per revolution and higher would be the accuracy of the position obtained. The step angle can be as large as 90 degrees and as small as 0.72 degree, however, the usually used step angles are 1.8, 2.5, 7.5 and 15 degrees.
Stepper Motor:
Construction:

Stepper motor is formed from the stator coil and rotor.

The rotor is the movable part which has no winding, brushes and a commutator. The stator is made up of multipole and multiphase winding, usually of three or four phases winding wound for a required number of poles decided by desired angular displacement per input pulses.

 

stepper motor

 Working:
Stepper motor works on the principle of electromagnetism.

The magnetic axis is enclosed by the electromagnetism stators.

Rotor and stator coil have poles which can or might not be teethed relying upon the categories of the stator coil.

Whenever the stators have energized the rotor, it moves to align itself along with the stator. In this fashion, the stators are energized in the sequence at different poles to rotate the stepper motor.

Due to the superb management of the speed, rotation, direction and position, these square measure of specific interest in process system, CNC machine, robotics, producing automation System

 Types of stepper motor:

1. Variable reluctance stepper motor.
2. Permanent magnet stepper motor.
3. Hybrid stepper motor. 

  1. Variable reluctance stepper motor:

Variable reluctance stepper motor has the straightforward style with soft iron, non-magnetic toothed rotor and wound magnetic force stators.

No attraction between the rotor and stator winding when the winding being energized since the rotor is not magnetised. When an opposite pair of winding has current switched to them, a magnetic field is produced with lines of force which pass from the stator poles through the nearest set of poles on the rotor. It gives the steps angle of 7.5 or 15 degrees.
2. Permanent magnet stepper motor:
Permanent magnet stepper motor has a permanent magnet rotor that is axially magnetised. It means that it has alternating north and south poles parallel to the rotor shaft. Each pole is wound with a field winding, the coils on opposite pair of poles in series. Current is supplied from D.C source to the winding through switches. The rotor is a permanent magnet and thus when a pair of the stator poles has a current switched to it the rotor will move to line up with it.

steps angle of this motor square measure one.8, 7.5,15,30,34 and 90 degrees.

  1. Hybrid stepper motor:

The hybrid stepper motor is that the combination of each permanent and variable reluctance motor.

It has a permanent magnet, toothed rotor made up two sections or cup, which are opposite in polarity and whose teeth are offset to each other.

The rotor set itself within the minimum reluctance position in response to a combine of mechanical device energised .Step angle of this motor are 0.9, or 1.8 degrees.

 

You can additionally watch this video to know the various sorts and dealing of stepper motor.

Advantages:

1. The rotation angle is proportional to the input pulses.
2. Full torque at standstill.
3. Very low-speed synchronous rotation is possible to achieve.
4. There are no brushes so it is reliable.
5. Speed is directly proportional to the frequency of the input as pulses; hence a wide range of rotational speed can be realized.
6. Low speed with high precision.

Disadvantages:

1. No feedback system.
2. Low effitiency.
3. May produce more noise.
4. Difficult to operate at very high speed.
5. For the smooth move, micro stepping is required.

Applications:

1. Factory automation.
2. Packaging.
3. Material handling.
4. Aerospace industry especially in avionics.
5. 3D pictures acquisition system.
6. Laser measurements.
7. Robotics.

 

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