Stepper Motor – How It Works

Stepper Motor – How It Works


Stepper Motor is a brushless motor that
rotates in steps. This is very useful because it can be precisely position
without any feedback sensor which represents an open loop controller. The stepper motor consists of a rotor there is generally a permanent magnet and it is
surrounded by the windings of the stator As we activate the widings step by step
in a particular order and let current flow through them, they will magnetize the stator and make electromagnetic poles respectively that will cause propulsion to the motor.
So that’s the basic working principle of a stepper motor. There are several different
ways of driving the stepper motor. The first one is the wave drive or single
coil excication. In this mode, we activate just one coil at a time which means that for this example
of motor with 4 coils the rotor will make full cycle in 4 steps. Next is the full step drive mode which
provides much higher torque output because we always have 2 active coils at a given time.
However this doesn’t approve the resolution of the stepper and again the rotor will
make a full cycle in 4 step. For increasing the resolution of the stepper
we use the half step drive mode. This mode is actually a combination of the
previous two modes. Here we have one active coil followed by two active coils
and then again one active coil followed by two active and so on. So with this
mode we get double the resolution with the same construction. Now the rotor will
make full cycle in 8 steps. However the most common method of controlling
stepper motors nowadays is the Microstepping. In this mode we provide
variable controlled current to the coils in a form of sine wave. This will
provide smooth motion of the rotor decrease the stress of the parts and
increase the accuracy of the stepper motor. Another way of increasing the
resolution of the stepper motor is by increasing the numbers of the poles of
the rotor or the members of the poles of the stator. By construction there are
three different types of stepper motors: permanent magnet stepper, variable
reluctance and hybrid synchronous stepper motor. The permanent magnet stepper has
a permanent magnet rotor which is driven by the stators winnings. They create
opposite polarity poles compared to the poles of the rotor which propels the
rotor. The next type, the variable reluctance stepper motor uses a non magnetize soft iron
rotor. The rotor has teeth that are offset from the stator and as we activate the windings in
particular order the rotor moves respectively so that it has minimum
gap between the stator and the teeth of rotor. The Hybrid Synchronous motor is a
combination of the previous steppers. It has permanent magnet toothed rotor and
also a toothed stator.The rotor has two sections which are opposite in polarity and their teeth are
offset as shown here. This is the front you commonly used hybrid stepper motor
which has 8 poles on the stator that are activated by two windings A and B. So if
we activate the winding A we will magnetize 4 poles which two of them
will have South polarity and two of them North polarity. We can see that in such a
way to rotors teeth are aligned with the teeth of the poles A and unaligned
with the teeth of the poles B. This means that in the next step when we will turn
off the A poles and activated the B poles the rotor will move counterclockwise and
it’s teeth will align with the teeth of the B poles.
If we keep activating the poles in a particular order the rotor will move
continuously. Here we can also use different driving modes like the wave drive, full step drive, half step drive and microstepping for even further increasing of the resolution of
the stepper. Thanks for watching and for more visit my official website HowToMechatronics.com

83 Replies to “Stepper Motor – How It Works”

  1. This is a great visual representation! Do you go into how increasing the number of steps per revolution effects the torque of the stepping motor in some other video? That is a very important consideration when determining how far to increase steps to gain smoothing. Thank you.

  2. Just what I needed: an animation. This makes much more sense! Only wish that there was a better animation of the hybrid, but you explained it well.

  3. i hate step motor in cd player,the coils wires are connected together and that works like shit even i provide the sequence pulse for it.

  4. why do modern printers don't use stepper motor instead of dc motors?………….Can a stepper motor be as precise as an Optical Encoder?

  5. Excellent video… I've watched quite a few stepper motor videos and this is the clearest explanation that I've seen.

  6. Is a Stepper motor or a switched reluctance motor AC motor or DC motor? Or simply put, is the current in a coil alternating or not?

  7. Блядь, вот почему в русском Ютубе нихуя нет про шаговые движки? Почему я должен смотреть объяснения от этого индуса? Кстати индус хорошо объясняет.

  8. Really nice video. At first i was a little intimidated when you introduced 2 other types of stepper motors but you explained them so well. I learned things today.

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