DC motors – how is it made? How it works?

DC motors – how is it made? How it works?


Welcome to PCB Heaven Techlabs Today i will show you what’s
inside a DC motor I have prepare myself a model of
a DC motor for this reason and as you can see this is
fully functional it can rotate eitherway clockwise
and counterclockwise and on the back side you can see the bearing that
holds the shaft and the shaft itself and the two poles that the motor
is powered from Instead of breaking the motor appart and explain each part
as i take it out I would rather prefer to
go backwards and i will start from a scratch
and build the motor from the beginning I strip the motor This is the basic part of the motor this is the shaft and on the shaft the two electromagnets are welded actually these are only the cores
of the electromagnets they still lack of the coils and the coils are actually the ones that
i will start with making the motor The coils are made of thin
single-core wire from copper that it has no plastic
shielding outside instead it has a special paint and this will prevent the short-circuit
between the windings This would be the fist coil of the
electromagnets the motor has actually two electromagnets
something that doesn’t happen in the real life but this motor is made only for
educational purposes and i tried to keep is as simple
as possible So, these are the electromagnets and now it’s starting to look
a motor again and it’s time to give some power
to the coils This is the tricky part
of the DC motor So, to provide the power i need
to build something that’s called commutator The commutator is actually a ring This ring is above the electromagnets and it is fixed on the shaft This ring rotates along with
the shaft and the ring is made of NON conductive
material, this is very important On the perimeter of this ring
there are two other parts That they are made of
conductive material This is the first part
of the commutator And it must be able to stand friction
in high revolutions you will see later why On the other side of this ring is
the other half of the commutator again it is made of the same
conductive material It has the same wire to provide
power to the coils Now both electromagnets have their wire
ending connected to the commutator Now look closer to these pieces They are actually NOT connected together There is a gap between them And on a real motor this gap is
times smaller than a millimeter On the other side there
is the same gap and now let’s take a look around So, we have make the commutator
piece Now it’s time to put something to hold
the shaft in position while rotating and what would be better than a set
of nice ball bearings The motor has actually
two bearings One above the commutator
and one under the coils The bearings are very inportant
on the motor And actually the bearings
along with the brushes are the parts that wear off
on a motor According to the theory of
operation of DC motors The electromagnets rotate inside
a magnetic field So now we need to make
a magnetic field And this field will be made out
of two permanent magnets placed one opposite the other now this is the first piece This piece of permanent magnet has it’s
north pole facing the coils of the motor The coils will rotate in front of
this magnet and they will be actually in
a very close distance 1 or 2 millimeters for small motors And now we need the other half of the…
another magnet with the other pole facing to the coils This magnet has the South pole
facing to the coils Between these two magnets there
is a permanent magnetic field and the coils will rotate inside
this magnetic field I will continue making
my motor The itnernal parts are
almost ready what I need now is a way to
provide power to the coils while they rotate. Remember that the poles of the windings
of the coils are both connected to the two pieces of the commutator There’s another part,
called, the “brush” And this is actually why this kind
of motor is called “brushed” motor The brush is a piece of metal that
acts like spring On one end, there is a conductive material
very durable, to friction like the one used for the
commutator usually this is made out
of carbon The metal will push this piece
on the commutator and so it will make contact
between these two on the other end of thie piece there is the power connector
of the motor this is where you connect
the power actually. The current goes from the power
connector through the metal spring and throught the carbon connector
directly to the commutator and then its provided in
both coils And of course there is another
brush opposite this one with the same structure and
operation of course It will give power to the other
piece of the commutator. Now, watch what happens while
the shaft is rotating. The brushes have always the
same polarity as provided by the
power supply, but as the shaft rotates, the polarity driven to the
coils is changed, because every time… for example the left commutator
goes one time to the positive and one time to the negative
power supply And this is how the electromagnets
change their polarity. That’s the tricky part of
the DC motor. Now it’s time to put it all together, and i will put the housing
of the motor. It has a proper place of course
for the ball bearing. And the electromagnets are also fixed
on the walls of this housing. That’s the housing. Our motor is almost finished. Its time for the final part. I don’t really know the name of this part. I will call it a cover, actually
its a cover! It covers everything. And it also has a place for
the bearing on top. It will hold the bearing
on top, and it also has two holes
for the power terminals And the motor is ready. Fully functional. Everything in position,
that’s it! Thank you for watching this video
and don’t forget to visit our website for more interesting
projects!

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