Inside a Washing Machine Motor: Explanation, Pinout, Teardown AND Experiments
Summary
TLDRThis video explores the inner workings of a washing machine motor, demonstrating how to identify pinouts, power it with AC or DC, and differentiate it from a standard DC motor. The host also discusses motor speed control, field coils, and potential applications in robotics and electric vehicles.
Takeaways
- 🔧 The video demonstrates a teardown of a Zeman's washing machine motor to salvage an electric motor and fitting belt.
- 🔍 The presenter explores the motor's internals to understand its pinout, enabling repurposing for various projects.
- 🔌 The motor's pinout is crucial for its functionality, and the video provides a detailed guide on identifying and utilizing it.
- 🏗️ The motor has a tacho coil for speed regulation, which is an important aspect of its operation.
- ⚙️ The video explains the differences between universal motors and ordinary DC motors, focusing on their construction and operation.
- 🔥 A safety feature, the thermal switch, is highlighted to protect the motor from overheating.
- 🔄 The video shows how to power the motor using both AC and DC, discussing the implications of each method on motor performance.
- 🔋 The presenter discusses the concept of self-excited motors and how they differ from separately excited DC motors.
- 📉 The importance of controlling motor speed and torque is emphasized, with demonstrations of how to achieve this.
- 🧲 The role of field coils in generating the magnetic field is explained, and their impact on motor speed and torque is demonstrated.
- 🛠️ The video concludes with experiments showing the effects of remnant magnetism in the stator pack and the possibility of using permanent magnets instead of field coils.
Q & A
What was the main purpose of the video?
-The main purpose of the video was to demonstrate how to salvage an electric motor from a washing machine, explore its internal components, and show how to power it with both AC and DC sources.
Why did the presenter choose to examine a Milliband washing machine motor instead of the Zeman's motor?
-The presenter chose to examine a Milliband washing machine motor because it was bulkier, more rugged, and he had a couple of them available for future projects, unlike the Zeman's motor which was precious due to its own transmission.
What is a universal motor and how does it differ from an ordinary DC motor?
-A universal motor is a type of electric motor that can be powered by both AC and DC sources. It differs from an ordinary DC motor, which typically uses permanent magnets, by having field coils or field windings that generate the magnetic field when powered by AC or DC.
What is the significance of the tacho coil in the motor?
-The tacho coil is used in conjunction with a small permanent magnet and a coil to read out the motor speed and control it. It is an important component for motor regulation.
What safety feature is the thermal switch in the motor?
-The thermal switch is a safety feature that protects the motor from overheating. It is conductive at normal temperatures but switches off when heated, preventing current flow until it cools down.
What does the term 'series wound' mean in the context of motors?
-In the context of motors, 'series wound' refers to a configuration where the field coils and the armature are connected in series, meaning the same current flows through both, affecting the motor's speed and torque.
How can the motor speed and torque be controlled when using a universal motor?
-The motor speed and torque can be controlled by adjusting the voltage across the armature and the current through the field windings. Using independent voltage or current sources for each allows for precise control.
What is a 'self-excited' motor and how does it differ from a 'separately excited' DC motor?
-A 'self-excited' motor is one where the field coils and the armature share the same current, meaning the voltage across them is not independent. This differs from a 'separately excited' DC motor, where the armature and field coils are powered by independent sources, allowing for separate control of speed and torque.
Why are iron filings used in the experiment with the motor's stator pack?
-Iron filings are used to visualize the magnetic field lines within the stator pack of the motor. They align themselves along the magnetic field lines, providing a visual representation of the field's structure.
What is the remnant magnetic field and why does it cause the motor to continue rotating even when the field coil current is shut off?
-The remnant magnetic field is the weak magnetic field that remains after the current through the field coils is shut off. It is caused by some magnetic domains in the stator pack retaining their alignment from when the current was flowing. This remnant field can cause the motor to continue rotating, albeit with reduced torque.
How can a universal motor be powered by DC using permanent magnets instead of field coils?
-A universal motor can be powered by DC using permanent magnets by placing them in a stationary position to create a constant magnetic field. The motor's armature can then interact with this field to produce rotation, eliminating the need for field coils.
Outlines
🔧 Salvaging Motors from Washing Machines
The video begins with a recap of the previous episode, where the presenter salvaged an electric motor and a belt transmission from a Siemens washing machine. The current episode focuses on examining the motor's pinout and demonstrating how to power it with AC or DC. The presenter introduces the motor salvaged from the Siemens washing machine and a similar motor from a Miele washing machine. They highlight the motor's components, including the pulley, stator pack, and ten-pin connector. The aim is to understand the pinout for practical use.
⚙️ Disassembling the Motor
The presenter starts disassembling the Miele washing machine motor by removing its plastic shield and metal arm, noting the presence of Torx screws. They reveal the internal components, including a ten-pin connector and a tacho coil. The video focuses on understanding the pinout by examining the connectors and identifying a thermal switch that protects the motor from overheating. The pinout diagram includes crucial safety and control aspects.
🔌 Powering the Universal Motor
The presenter explains the significance of the motor's brushes and commutator, identifying the motor as a universal motor rather than a simple DC motor. They detail the process of connecting the motor's field coils and armature in series, powering it with AC using an isolation transformer. The presenter addresses the issue of uncontrolled motor speed and proposes controlling the motor with two independently regulated DC voltages for precision control.
🔋 Controlling Motor Speed and Torque
The presenter demonstrates controlling the motor speed and torque using a lab power supply with independently regulated DC voltages for the armature and field coils. They explain the concept of series wound, shunt wound, and separately excited DC motors, illustrating the differences with practical experiments. The focus is on achieving precise control over motor speed and torque by adjusting the voltage and current through the field coils.
🧲 Exploring Magnetic Fields in Motors
The presenter explores the role of field coils in creating magnetic fields within the motor's stator. They conduct experiments with a compass and iron filings to visualize the magnetic field lines. The video explains how reversing the current through the field coils reverses the magnetic field, enabling the motor to run on AC. The presenter also demonstrates the concept of remanent magnetism and the possibility of using permanent magnets instead of field coils for DC operation.
🛠️ Practical Applications and Future Projects
The video concludes with a summary of the experiments and their implications for repurposing washing machine motors. The presenter discusses potential applications, such as using the motor for robots or electric vehicles, and mentions ongoing projects involving Arduino motor control and mechanical drivetrains. They encourage viewers to provide feedback, support the channel on Patreon, and look forward to future episodes focusing on motor control and applications.
Mindmap
Keywords
💡Teardown
💡Electric Motor
💡Pinout
💡Universal Motor
💡Stator Pack
💡Commutator
💡Field Coils
💡Tacho Coil
💡Thyristor Circuit
💡Isolation Transformer
💡Magnetic Field
Highlights
Teardown of Zeman's washing machine motor to salvage electric motor and fitting belt.
Exploration of motor internals to determine pin out and powering options with AC or DC.
Differences between universal motors and ordinary DC motors discussed.
Salvaged Miele washing machine motor used for demonstration, noted for its transmission.
Brief examination of the motor's nameplate for specifications and regulation details.
Removal of plastic shield to access the motor's internal components safely.
Identification of the tacho coil and thermal switch within the motor for safety.
Demonstration of the temperature switch's function as an overheating protection.
Pin out diagram creation for the ten-pin connector of the motor.
Explanation of the motor's brushes and their connection to the commutator.
Discovery of unused center tabs of the field coils indicating series connection.
Simple powering of the motor by connecting field coils and armature in series.
Challenges of controlling motor speed without active speed control.
Experiment with self-made lab power supply to control motor with independently regulated DC voltages.
Observation of motor behavior with field coils current shut down and implications on torque.
Experiment with iron filings to visualize the magnetic field inside the stator pack.
Demonstration of motor operation with only permanent magnets and no field coils.
Discussion on the potential for using Arduino to control motor speed with sensor readouts.
Upcoming projects involving motor control circuits, Arduino motor shields, and mechanical drivetrains.
Transcripts
hello friends in my last episode I've
shown you a teardown of a Zeman's
washing machine and I did that in order
to show you how you can salvage an
electric motor and a fitting belt
transmission in this video I'm now going
to go a step further and take a look
inside one of these motors in order to
show you how to find out their pin out
and how to in principle power them with
both AC and or a DC and after that we're
going to explore some of the things
happening inside the motor and talk
about the differences between this type
of motor and an ordinary DC motor
so here is the Zeman's washing machine
motor that i salvaged in my last episode
but it is kind of precious to me because
it came with its own transmission and
that is why I don't want to take it
apart instead we will take a look inside
one of these Milliband washing machine
motors here that I happen to have a
couple of and that I also want to use
for future projects it's a little
bulkier a little more rugged but very
similar in build and works on the same
principles so let's take a closer look
at this motor and then take it apart we
have again a pretty small pulley for a
ribbed belt sitting on the pretty
massive motor shaft and then we have
this bulky rectangular stator pack or
package made from transform illumination
that was also welded together on the
backside of the motor we have a plastic
cover and we find a tenpin connector and
one of the main reasons for this video
is to show you how to take a look inside
of one of your motors and find out the
pin out of the connector on your motor
because without that a motor like this
is pretty much useless to you but let's
take a brief look at the nameplate first
and this motor by the way is salvaged
from a 25 to 30 year old miele washing
machine and those are just as easily
available now as the Siemens washing
machines in the last video it also says
moto fu jager but weep on here and that
means that this motor must be regulated
and that is between 300 and 11,500
revolutions per minute which it states
down here and we're going to talk a
little bit more about that later in this
video so I begin to tear down by
removing this plastic shield here and it
seems to serve a double purpose for one
maybe it protects the inside of the
washing machine a little bit from the
dust coming from the brushes inside the
motor but it also makes the motor a
little quieter I think and that is why
we have some insulation material in here
and in the next step I remove this metal
arm here and I do that by unscrewing a
bunch of rather thick Torx screws and
that is something that you didn't see
too often in Germany
thirty years ago but in these older
Miele washing machines you can already
find torques all over the place and on
the backside of the motor we can now see
a plastic shield connected to the motor
by four screws and we remove those as
well but we can see that it's actually
not one piece but two pieces of plastic
that are connected together and by
unhooking the top cover here I can take
it off and we can take a closer look
inside and we see traces leading to our
ten pin connector and we can see that
two of the connectors are pretty charred
we'll take a closer look at that in just
a second and then we can try to wiggle
off this entire plastic shield but you
have to be very careful because you
don't want to damage the motor brushes
that are connected to this plastic part
and here on the backside of the motor
shaft we can also find a small permanent
magnet and that is used in conjunction
with a coil sitting in an plastic shield
in order to read out the motor speed and
control that but we're going to talk
about that in another video but we can
now start to determine and write down
the pin out of that ten pin connector
and for that I have taken this picture
here of another well optically is
slightly different but electrically
identical shield I took this from
another motor of the same type now we
have seen that these two traces here
just lead to this tacho coil and we can
write that down
so let's take a look at those two pins
that are a little burned or charred and
we can see that this is actually a
component that we can pull out here and
what this is is a temperature or a
thermal switch and let me demonstrate
how that works so as you can hear the
continuity tester of the DMM shows us
that this temperature switch is
conductive now I'm heating it up
and as you can see now it has switched
off and we wait for a while until it has
cooled down again and now it's
conductive again so this is just a
safety measure used to protect the motor
from overheating and let's write that
down
our little pin out diagram here as well
the outermost pin on the left side
simply connects to a resistor at 10 mega
ohm resistor that just ends in the air
right now normally this would be
connected via one of the screws that I
removed to the housing or enclosure of
the motor and this is where PE the
protective earth connector would be
connected with that you can also see on
this connector cable for the washing
machine motor but well when you operate
this motor on your desk for example it
might be smarter to connect the
protective earth directly to the housing
and remove that 10 mega ohm resistor but
I don't want to give any conclusive
advice about this yet we'll have to talk
about these safety issues once we are
really running it via the line voltage
in this video I'm kind of doing that but
I'm using an isolation transformer and
when you have an isolation transformer a
connection to protective earth wouldn't
make any sense if you don't know what
I'm talking about watch my video about
the power grid which I linked in the
video description so the 5 pins that we
have determined so far are important for
safety and control aspects of the motor
but they are not crucial if you just
want to power up the motor so let's get
to the really crucial parts and among
those are these two brushes here which
connect to the commutator and power the
armature of the motor and the brushes
are connected to these 2 pins here and
let's write that down in our little
diagram here as well and the symbol that
I use here for the commutator for the
armature is the same one that you use
for ordinary DC motors with permanent
magnets the little black things touching
the circle in the middle reading em are
supposed to be the brushes but this
motor is not a DC motor at least not a
DC motor with permanent magnets it's a
universal motor
and what that actually means well we'll
have to talk more about that but one
thing that it means is that this motor
has field coils or field windings and
they are connected to the remaining pins
so let's explore that a little further
so if we take a closer look at the Stata
pack and the field coils themselves we
can see for actual connectors leading to
the coils and the plastic shield has
four blade connectors but only two of
those connectors actually connect to the
field coils while two of them just go
into these plastic indentations here
connecting to nothing and that is
because two of the connectors on the
field coils are just two ends of the
coils being connected together by this
little piece of metal here and that
simply means that a few coils are
soldered together in series and that
only it's two ends are effectively used
and let out of the motor so we have two
Center tabs or taps of the field coils
if you want that were never used with
this motor though so now we have the
complete pin out and well one of the ten
pins is actually not connected that's
why it says NC you know that pin just
leads to those two blade connectors that
just go into the plastic indentations
and lead nowhere but with a pin out
we're now able for the first time to
power up the motor and I'm now going to
do that in the most simple way possible
and that is by simply connecting the two
field coils and the armature in series
and that is the standard configuration
for the universal motor and well
typically Universal motors are powered
by AC and that is what I'm going to try
now and I'm using my adjustable
isolation transformer here and I will
step up the supply voltage to around
half what it's rated for that is 115
volts out of 230
[Music]
[Music]
so here again we encounter a problem
that I have tried to describe and solve
before in my earlier videos about
washing machine motors and that is if
you have a series wound DC motor or a
universal motor and you power that up
without actively controlling the motor
speed then it will just go through the
roof and the motor will turn faster and
faster and faster and even with only
half the supply voltage and no
mechanical load on the motor shaft
11,500 rpms is left behind very quickly
and this can be harmful for the motor
and is also not very useful for most
applications now I have used a motor
like this successfully before without
speed control and that is when I build
my ducted fan in the ducted fan project
the thing is that you have a constant or
at least a constantly present load and
represented by the air and the air
resistance so that the motor will settle
down at some kind of maximum speed but
well I still operated it at only I think
80 volts or something if you want to
have something like a robot or a vehicle
or anything where you need more
precision control and more torque and
less motor speed then you will have to
control the motor more sufficiently and
it is not enough to just connect it to
the line voltage but I have presented
one solution for that in my video about
how to reuse washing machine motors and
that was in the form of a very simple
thyristors circuit that kept the motor
at constant speeds but it had its
limitations maybe I can still improve it
but right now I'm working on a
completely different approach to solving
this problem so let me show you what I'm
talking about so you can already see me
connecting the motor to my self-made lab
power supply here and I'm doing that
because I want to use two independently
regulated DC voltages to control the
motor let's take a look at the simple
circuit diagram again and let me explain
to you the different options that we
have we had connect
the field coils and the armature in
series and used AC to power the motor I
would call this the universal motor mode
of operation now if we were to use DC
instead of AC then we could call and see
this motor as a series wound self
excited DC motor series wound because
field coils and armature are connected
in series and self excited because the
external field in this data is not
generated by permanent magnets but by
field coils but also self excited
because the current flowing through the
armature is the same current flowing
also through the field coils meaning
that the current through the field coils
or the voltage across the few coils is
not independent of that across or
through the armature and that's why
that's called self excited now if we
were to connect the field coils in
parallel or in shunt with the armature
we'd call that a shunt wound DC motor
and it's again self excited because the
voltage across the two things here the
armature in the field coils are not
independent from each other but if you
separate both and then have two
independent voltage or current sources
powering the armature on the one and the
field call on the other side we're
talking about a separately excited DC
motor it's neither
series nor shunt wound because the two
elements are not connected together
and using this motor as a series wound
DC motor is basically what I did back
with the thyristors circuit because that
actually used DC as well but well the
field coil and the armature were still
connected in series connecting the two
in parallel doesn't really make any
sense
because the field coil has a very low
resistance and it is just not built to
handle the large voltages that we can
put across the armature the few coil
were just overheat and well the
insulation would melt at some point
doesn't really make much sense so the
other option here really is to control
the two separately and let's just try
this in a little experiment the analog
voltmeter shows the voltage across the
armature and the analog ammeter shows
the current flowing through the armature
the reading on this read seven segment
display here is the voltage across the
field coils and the DMM displays the
current flowing through the field coils
we are now applying a voltage across the
commutator and the motor starts spinning
yet other than in the example before it
now will not run away but stay at a
constant speed or at a maximum speed
we're stepping up the voltage across the
commutator and of course the motor
speeds up but again it keeps its speed
and let's go through 30 volts and we can
see the same result
now we can adjust the motor speed and
torque by adjusting the voltage across
or the current through the field winding
let's step up that current and as you
can hear the motor speed goes down and
when we decrease the voltage across the
field winding or into the current
through it the motor speed goes up
thirds of course best if you control
both the voltage across the commutator
and the current flowing through the
field winding but in theory you can have
a fixed supply voltage for the motor and
then a variable voltage or current for
the field winding in order to control
the motor let's make an additional
observation here I now shut down the
current through the field coils
completely zero and pair and I keep a
voltage across the armature and as you
can see the motor is still spinning and
even speeds up but I can now very easily
just grab the shaft and stop the
rotation because there's almost no
torque here so why does that happen
well we'll hopefully understand it later
in this video but in order to make that
happen it's maybe time to learn a little
more about the field coils themselves
why are they even there here we have a
windshield wiper motor just an ordinary
DC motor like it would be used in
automotive applications we open it up
and inside we find an armature that
looks not exactly like the one from the
washing machine motor but it has a lot
of similarities there is a commutator
here for example and commutator brushes
but when we take a look inside
the housing of this DC motor we find
permanent magnets it's what in German is
called a permanent a zig-zag leash to a
motor a permanently excited DC motor may
be not a very usual English word so most
people just call it a permanent magnet
DC motor or something like that but here
for example we have a Brett cutting
machine that I found on the trash the
other day and let's
take that apart and inside we find a
universal motor and this universal motor
again has an armature a commutator
brushes but then this weird state a pack
and a coil sitting on it and the
difference here really is that this
motor is not powered by DC but by AC by
the line voltage and for some reason it
is necessary to have a field coil rather
than permanent magnets if you want such
a motor to be powered by AC well why is
that
well let's take a look at another little
experiment so here we have our state a
pack with the two field coils in series
and that are now going to be hooked up
to our lab power supply right in the
middle I have now placed in ordinary
compass and that is sitting on just a
piece of rubber that puts some distance
between the surface and the compass
itself I will now apply a voltage to of
the field coil and you can see a
rearrangement of the needle and the
rough direction or orientation of the
flux lines inside the stator pack is
like this but when I now reverse the
polarity of the voltage across the field
coils you also see a 180-degree
rearrangement of the magnetic needle so
by reversing the voltage across the
field coils the direction of the current
flowing through these coils is also
reversed resulting in a reversal a
180-degree reversal of the flux lines
inside the stator and this can also be
used for example to reverse the
rotational direction of the armature in
such a motor it is also the reason why
it is possible to use such a motor
rather than an ordinary DC motor with
permanent magnets with AC because when
you connect an alternating voltage an
alternating current with periodically
changing direction will flow through the
field coils also creating a magnetic
field inside that will likewise change
its direction periodically and the same
thing happens at the same time in the
armature
so these two 180 degree reversals are
synchronous and they can't should cancel
each other out
while when you apply an alternating
current to a DC motor with permanent
magnets only the field in the armature
reverses while this field here stays
stationary and therefore no rotation
comes to be so when repurposing a
universal motor as a DC motor like what
I'm doing here it would actually not be
necessary to have field coils you could
just have permanent magnets but one
thing that is good about field coils as
well is that you can strengthen or
weaken the field in the stator which
then results for example in more speed
or otherwise more torque in the rotation
of the shaft as we have seen in the
experiment before so since the washing
machine motors come with field coils we
might as well use them to our benefit
but I wanted to explore the magnetic
field inside a little more so I took now
this very small compass here to see how
the field lines within the stator are
arranged and it seems that they are
pretty much parallel and in order to get
a better picture I also got myself some
iron filings and let's see what that
will look like
well of course it's a little more
complex than just straight lines that
are in parallel to each other but I
think it's pretty close but when we shut
off the current
of course the iron filings collapse but
still if you now insert a compass into
the stator pack there is still a
rearrangement of the needle well and why
is that I mean if I try to stick the
iron filings to this data they just fall
through it well the answer is that there
is still a weak magnetic field here a
remnant magnetic field because some of
the magnetic domains are still pointing
in the direction that was once forced by
one of the few coils when a current was
flowing through them and that is also
the reason why the motor still rotates
and even speeds up when I shut down the
current through the field coils entirely
the remanent magnetism of the state
effect and here I have now completely
removed the field coils themselves so
that you can see what the pack or
package actually looks like and here
again you can witness the reaction of
the needle to the remnant field but
there is one more little thing that I
wanted to do because I said that you
could use a motor like this also with
permanent magnets and I just wanted to
prove that to you so I have now put the
motor back together missing only one
very crucial piece and that is the
stator itself or the stator pack with
the field coils and when I now step up
the supply voltage across the commutator
or armature the current goes up but the
motor doesn't rotate now let's try
something a little different here the
demonstration here we have an ordinary
iron file and on that is sitting a
strong neodymium magnet and I'm just
placing this you're roughly on top of
the motor now let's step up the voltage
again
and it's give up you see that let's give
them what a little momentum with my hand
it's struggling but you can't see that
there is a rotation and that should
suffice to show you that you really only
need a stationary magnetic field when
powering such a motor with DC and you
could add permanent magnets this type of
motor if you wanted to and use it with
DC and not use the field calls at all so
that was today's episode and I hope it
helped you a little bit in maybe
figuring out the pin out of a washing
machine motor that you have lying around
somewhere and that it gives you an idea
what kinds of modes of operation there
are for these types of motors and maybe
also you learn something about the
differences between Universal motors and
permanent magnet DC motors now I'm using
my experimental setup here with the lab
power supply to determine just the right
values to build a much simpler circuit
that I then hopefully will present to
you guys as a simpler solution to this
problem on the other hand I have also
started to work with the Arduino and
build something like a motor shield for
the Arduino so that we can for example
control the speed of these motors by
having sensor readouts for example of
the tacho coil or other sensors like
magnetic sensors that I have used before
and then I'm also working on a
mechanical drivetrain so that I can use
maybe two of these motors as a drive for
a robot or some kind of small electric
vehicle so those are at least three
extremely interesting projects in my
opinion and the next couple of videos
will revolve around this topic again so
if you like these ideas if you like the
little experiments that I've shown you
or other things please let me know in
the comment section and if you can spare
a buck or two well then maybe think
about supporting my channel on
patreon.com /tpa I sure could use it and
it was
helped out a lot so I hope you like this
and to see you soon
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