15-03-2011, 10:55 AM
presented by:
.Ashwini Sanu
.Divya Kanekal
Divya Chawan
Rajeshwari T
Rashmi H
STEPPER MOTOR.pptx (Size: 132.92 KB / Downloads: 103)
Basic principle:
Permanent Magnet stepper motors incorporate a permanent magnet rotor, coil windings and magnetically conductive stators. Energizing a coil winding creates an electromagnetic field with a north and south pole.
The stator carries the magnetic field which causes the rotor to align itself with the magnetic field. The magnetic field can be altered by sequentially energising or ‘’stepping’’ the stator coils which generates rotary motion.
INTRODUCTION
Stepper motors commonly have a permanent magnet rotor (also called shaft) surrounded by a stator.
There are also steppers called variable reluctance stepper motors that do not have a permanent magnet rotor.
WORKING OF A STEPPER MOTOR
The most common stepper motors have four stator windings that are paired with a center -tapped common. These are called as four phase or unipolar stepper motors.
The center tap allows a change of current direction in each of the two coils when the winding is grounded , thereby resulting in a polarity change of the stator.
The stepper motor has a fixed repeatable movement.
This is possible as a result of basic magnetic theory where poles of the same polarity repel and opposite poles attract.
The direction of the rotation is due to the current through the stator poles . As the direction of the current changes polarity changes resulting in reverse rotation
STEP ANGLE
Step angle is the minimum degree of rotation associated with a single step.
The various motors will have different step angles.
STEPS PER REVOLUTION:It is the total number of steps needed to rotate one complete rotation or 360 degrees.
For example if step angle is 2degree,then for one
complete rotation 180 becomes the steps per revolution.