Modifying Motors/Generators

[Farmhand]

Hi all, This thread is for all different kinds of motor/generator modification's.
I know there is already a lot of other motor generator threads but I thought a
thread with some devices developed from existing common equipment or
household appliances might be fun.

To show my first bit of progress toward exploring this area of experiment I
present the "Generating Field DC Motor". I used a vacuum cleaner motor which
I think was a 2000 watt rated vacuum. I believe it's a universal motor I tested
it with 120v AC first as it was originally wired with the armature in series with
the field coils, and it went well with 50 watts.

Generating Field DC Motor 24v input - YouTube

Generating Field DC Motor - YouTube



Then I separated the armature and the field coils and inserted another coil
between the field coils to make the two field coils in series with the other coil
then by powering the armature with DC from a battery the motor works and I
can get power out of the field coils as well.

Being out of an abused vacuum cleaner it's not as efficient as it could be
it seems to work well from 24 volts and has quite a bit of power. I'm
interested at looking into using some common appliance parts/motors to
experiment with.

I was also thinking about trying to use it the other way around by using a
motor controller to pulse the field coils then take the power from the armature.

[Guest]

Hi Farmhand, what an interesting project...

I'll have to look up some specifics on how these motors work,
because from your diagram it isn't registering to me how the
armature generates torque. Your motor has two coils and two
brushes, yet they aren't connected. Normally I'd guess the
coils would receive a pulse from the brushes. Otherwise it
seems like the armature would have the coils and it could
pulse against a set of magnets, as how an alternator is built.

Does the added coil have an effect on the output, or have
you included it for some other reason?

Recently I've obtained an old fan motor, perhaps candidate
for experimenting with; it registers at around 12ohms.

[Guest]

There are a couple of other ones as well... small motors
but what about rewinding with thicker wire? Also what about
replacing the magnetic strips with Neodymium? I'm having
difficulty determining their N-S polarity orientation with
a compass.

[mbrownn]

Hi all, This thread is for all different kinds of motor/generator modification's.
I know there is already a lot of other motor generator threads but I thought a
thread with some devices developed from existing common equipment or
household appliances might be fun.

To show my first bit of progress toward exploring this area of experiment I
present the "Generating Field DC Motor". I used a vacuum cleaner motor which
I think was a 2000 watt rated vacuum. I believe it's a universal motor I tested
it with 120v AC first as it was originally wired with the armature in series with
the field coils, and it went well with 50 watts.

Generating Field DC Motor 24v input - YouTube

Generating Field DC Motor - YouTube



Then I separated the armature and the field coils and inserted another coil
between the field coils to make the two field coils in series with the other coil
then by powering the armature with DC from a battery the motor works and I
can get power out of the field coils as well.

Being out of an abused vacuum cleaner it's not as efficient as it could be
it seems to work well from 24 volts and has quite a bit of power. I'm
interested at looking into using some common appliance parts/motors to
experiment with.

I was also thinking about trying to use it the other way around by using a
motor controller to pulse the field coils then take the power from the armature.

WOW, I'm impressed. I think you have created a DC induction motor

Let me explain.

When the current passes through the rotor a rising magnetic field is created. this would normally rise to a fixed point but at the same time it is inducing a field in the stator coils causing the rotor to turn. When the rotor turns the inductance changes as the commutator switches so now you have a varying field. It is still DC but it is varying in magnitude allowing the induced field to continue to oppose the rotor.

Universal motors are more efficient on DC than AC because we are not changing the polarity of the stator. I think you need to measure the output mechanical power. If it is more efficient than about 35% I think this will be proven.

With your induced current being in the outer coils it makes it simple to tap some of this. You could place a a high wattage bulb in series with your diodes and it should light.

If the combined mechanical power and light bulb is more than 60% of the input power, using a 3 battery setup would possibly bring it into overunity as additional power will be collected in the return line battery.

The third winding is probably causing a phase shift in the field coils.

Does my explanation make sense to you?

I need to build one of these

[mbrownn]

Obviously pulsing it would improve the efficiency further

[mbrownn]

Try replacing the third coil with a transformer, this may make it easier to draw power from the system. What's the signal look like on the scope from the third coil.

I love universal motors, there is so much you can do with them, Its like they are wanting to give you energy.

[Farmhand]

Hi Geo and mbrownn, Thanks mbrownn I think you just explained to Geo for
me how the shaft gets torque. You're right it is more efficient with DC and
much more efficient with the windings as normal and with low voltage DC like 24 volts.
Which is strange because the windings are quite low resistance. I used the
extra coil between the field coils to raise the voltage, a transformer there is a
good idea, but it's so much more efficient with the field coils in series with the
armature, two sets of field coils would be good or a DC bias current or something.

It's just so easy to supply DC from a battery and let the commutator do the work.

It will glow a 25 watt incandescent bulb but just a bit I measured about 5 watts.
This is just something I did while messing around, maybe it could be made
better or with different motors.

So many things to try and think about, I would think that adding some small
permanent magnets in the right place would allow better use without powering
the field coils, I'm guessing when the field coils give current they make a field.

For some reason when i place the neos in there it make it slow down, maybe
they are too strong. I also noticed as the motor speeds up the magnetic
intensity skews slightly in the field, rotating a fraction the same way as
rotation (I think).

Anyway it is interesting and surprising it even ran when not energizing the
field. Wierd it can run well from 24 volts with 50 watts and is made to run
from 240 v it does have a SCR or triac motor speed controller PCB I saved as
well.

Cheers

P.S. It is a bit of a pain removing the cowling from around the impeller I drilled
a hole in the dome cowling and peeled it off like a sardine tin. I can be
more specific if need be. I had to clean the motor and free up and oil the
bearings as well.

..

[Farmhand]

Geo, Those microwave fan motors can be handy but I don't think they will run
on anything but AC at around the correct Hz, I found that to power them
from my square wave converter I must use at least one series capacitor to
limit the current and prevent nasty reactions.

I kinda wanted to try to stay away from using permanent magnets, those fan
motors can be difficult to find the poles in.

I was thinking before i get too carried away I should quickly check out some
other motors just to see how they are built.

I've decided I might try to wind a few turns on top the field coils and see
what happens. I got an interesting result earlier by reconnecting the coils as
they were originally then leaving one field coil out of the powering circuit and
leaving the other field coil out of the output circuit but including the armature
in both. Still everything relies on using the shaft power as well, this motor has
a poor chance of good coupling of the shaft to different loads.

Cheers

[Guest]

Then the rotor spins when the load is supplied
from the generator field coils? This would mean the output is
resonating the motor! When a load draws current from
the motor coils it normally causes drag on the system rather
than increasing the torque if I'm not mistaken. How this works
is still a tad confusing.

What would happen if your third added coil was bifilar with
one input and output and the first of the two connected in series
with the other getting the magnetic fields to collide? Couldn't
any extra emf be captured somehow and sent back to the battery?

[mbrownn]

I would still like some torque and speed figures. Normal induction motors are surprisingly efficient on AC so figures for this would be very interesting. I think it may have more power when wired normally but is it more efficient?

For the bulb, try a 6v or 12v 60w because I think the voltage will be low in the field windings.

Again with the transformer use the output side of a 6 or 12v transformer so it is acting as a step up because we want to keep the resistance low.

Reducing the number of turns on the field coils or increasing the wire size should increase the amps and torque due to lower resistance. Note that the rotor winding on an induction motor is practically zero ohms.

Very nice work Farmhand.

[Farmhand]

Geo, It does spin without the field coils even connected to anything but it
seems that if there is direct current flowing in the field circuit the correct way it
is more efficient. I haven't really wrapped my head around it yet, but put it this
way. With the motor wired as original it uses just under 1 amp with 24 volts, but
spins slower too. With no field coils in the power circuit the input is about 2 amps
there is about 10 mH less inductance but only a few Ohms less the rotor spins
up faster too but takes longer to do it, then when loading the field coils I don't
think a whole lot happened. I'm setting it back up again so I'll take note.

Cheers

[Peculian]

Thanks Farmhand for this topic.

Now just a simple idea:
What if you put different capacitor values at the coils you added up in series
or parallel ?
This is just an idea, nothing more.

[citfta]

Series vs shunt

Hi Farmhand,

You may already know most of what I am posting because I know you have been studying a lot, but I'll share this for those that may not have a good grasp of how these types of motors work. You have modified it to be a shunt wound motor which means the fields are in parallel with the armature instead of in series with it. This type of connection of the fields has some advantages over a series connected motor. I believe you are still getting it to run because of some residual magnetism in the field cores. And since you have a complete circuit with the coils and the bridge this allows some current to flow in the field coils which would give the motor enough torque to allow it to run. Have you tried seeing if the motor will still run if both field coils are not connected to anything? My guess would be it will barely turn if at all, and the armature current will be pretty high. This is because there is no BEMF being generated without the influence of the field.

In industry I worked on DC shunt wound motors up to 50 HP. When the field current is at the normal rated full field current the motor will develop almost full torque at very low armature voltage. One of the motors I worked on was driving a 40 ft milling machine table. When they were doing actual milling I have seen that motor move that table with only 2.5 volts on the armature and it was turning so slow you could count the armature segments go past the brushes. Amazing to watch a motor have that kind of power and turn so slow.

When the motor has full armature voltage and full field current it will be running at its rated speed and torque if not overloaded. If the motor is not loaded too heavily you can reduce the field current and the motor will speed up. Of course it will draw more armature current until the it gets to the speed where the BEMF limits the armature current. In this condition you have also reduced the torque of the motor although that is usually not a problem since the equipment is already up to speed. There are safety circuits built into the motor controllers for these large motors because of the potential for extremely high current in the armature if the field current were to fail. The current could go as high as several hundred amps or even up to a few thousand amps. And the motor would continue to accelerate until it or the device it was driving was destroyed.

So you can see that the field current has an impact on how the motor will run. Increase field current and you increase torque and limit speed. Decrease field current and you increase speed and decrease torque. These two statements assume you are keeping the armature voltage the same.

I really like the idea you have come up with for experimenting with a universal motor. I have never thought about taking the power off the field windings like that! I want to try that as soon as I get caught up on some other things I have going on. Thanks for sharing that idea.

Later, Carroll

[Guest]

Would there be any change in performance through pulsing the armature with
a capacitor instead of connecting it to the battery? With a second capacitor
on a CDI circuit in series with the emitter of the armature coil, it seems
like it would collect the emf output of the coil and could then be used alternately
to for some purpose during the off pulse of the motor.

One of the 12v fan motors from earlier is now providing an output; having
first rewound two of the stator coils after manually figuring out how they are
wrapped. This particular fan had the opposite coils in series. It now has
three of them in series and one that will be used to pulse the rotor. There's
enough room left on the stator for a secondary coil to be wrapped around one
of them for sensing when to pulse... or a reed switch and custom magnet rotor
could be positioned on top.

Through the use of another coil in series with the other three, could it possibly
obtain a suitably higher voltage with which to charge a 12V battery?

[ Fan Rotor Generator, 4.7uF ]

[Farmhand]

Hi Cifta, Thanks for the explanation It will run also with the field
coils unconnected but as you point out the armature current is high, it does
speed up differently, I think what I was seeing in the video with 12 volts is
when I pushed on the shaft to load it a bit the input increased (armature current), which
increased the field current slightly, which then reduced the input power while
maintaining speed, those small batteries are quickly drained by 2 amps. I'll
setup the same arrangement tonight and make a better shorter video. I've
cleared some space. I'll show more clearly the wiring and stuff
I've got a better meter as well, I destroyed that analogue amp meter, it's
toast.

Geotron, I think I see now what your doing there, that's a cool experiment. I
think if you add another coil in series with the output coils outside of the motor
it will raise the voltage for sure, I think it's like an auto-transformer effect
(variac). I like the idea of the fan motor/generator, I think slider replaced the
flexable magnets in a fan with little neo's and it worked ok because they stuck
to the steel inner cylinder thingy in there.

Cheers

P.S. About the broken meter, I think I'll keep the meter even though it's
broken, I accidentally made a short circuit in reverse through the meter with
2 batteries in series then I accidentally did the same thing the other way
around, haha now it reads a maximum of 2 amps regardless of if the current
through it is more, but it does read down to zero. I should have used a
5 amp fuse.