Alternative Power sources - "print motor" servo as low speed generator??

Author

"print motor" servo as low speed generator??

clare at snyder.on.ca

2006-03-11, 12:21 am

Has anyone tried using a disk armature brush type DC servo motor for a
wind generator? I have 200 watt 42 volt and a 500 watt 85 volt that
I'm thinking about fastening a prop to ....... Both are rated at 3000
RPM.
Have an old 3 blade adjustable pitch ultralight prop hanging in the
shed too. Guess I'll chuck the motor into the old 1/2 inch drill and
give it a try tomorrow with a voltmeter attatched. The lathe would be
better, but it's only a 7 incher, and the motor is a bit bigger, I
think.
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clare at snyder.on.ca

2006-03-11, 6:21 pm

At 600 RPM the 500 watt rated (at 2500 rpm) 84 volt motor produced
about 15 volts open circuit (run up with my old 1/2 inch drill with
voltmeter attatched)
Connected to 12 volt battery that was a bit low on charge(11 volt
terminal voltage) it turned 400 RPM.No load.
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FukUSpamer@fukspamer.com

2006-03-12, 1:21 am

I already did this experiment, used servo motor with ordinary fan hooked up
to its shaft and motor generated almost 200Volts. Here is the link of the
motor and 2 small video clips ont he same page:

http://69.253.223.129/motor2.htm

clare at snyder.on.ca

2006-03-12, 6:21 pm

On Sat, 11 Mar 2006 23:50:15 -0500, "FukUSpamer@fukspamer.com"
<fukuspamer@fukspamer.com> wrote:

>I already did this experiment, used servo motor with ordinary fan hooked up
>to its shaft and motor generated almost 200Volts. Here is the link of the
>motor and 2 small video clips ont he same page:
>
>
>http://69.253.223.129/motor2.htm
>
>
>
>
>
Except that is an AC servo motor, and I'm sure that 200 volts dropped
of to less than 10% of that under load.

Totally different animal, regardless.
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meow2222@care2.com

2006-03-14, 6:21 pm

clare wrote:

> At 600 RPM the 500 watt rated (at 2500 rpm) 84 volt motor produced
> about 15 volts open circuit (run up with my old 1/2 inch drill with
> voltmeter attatched)
> Connected to 12 volt battery that was a bit low on charge(11 volt
> terminal voltage) it turned 400 RPM.No load.

At full whack in motor mode the back emf will be most of the terminal
voltage. Thus if you run it in gen mode at 1/5th rated speed you'll get
most of 1/5th rated terminal voltage out.

is that 15v ac single phase? If so, you need less. 14.4v is plenty to
charge a12v lead acid, though I'm told 15v is nice for occasional
equalisation. One can get 14.4 or 15 dc from what ac voltage?

Rectifier drop = 2-3v for a silicon bridge rec, so we need an ac output
with peak of 14.4+2.6 = 17v. RMS V = 17/1.414 = 12v ac.

With 15v offload @ 600rpm, you'll get 12v offload @ 480rpm. And you'll
get that onload at somewhere around 530rpm.

You'd get that at slightly lower speed using a mechanical rectifier, if
prepared to put up with one, since you could lose the rectifier V drop
that way, but I'd have thought its still too fast to make a good
windgen. You'd get significantly more mileage if you used a switch mode
convertor, and using mechanical rectification on the input would
increase output significantly.

Although you could get current out for more of the cycle using a choke
rectifier, the price is you'd have to run the gen significantly faster
to get it.

Any motor rated at thousands of rpm gives you an immediate problem.
There are various ways round it to some extent, but a rewind would sure
make life easier.

NT

clare at snyder.on.ca

2006-03-15, 2:21 am

On 14 Mar 2006 13:35:38 -0800, meow2222@care2.com wrote:

>clare wrote:
>
>
>At full whack in motor mode the back emf will be most of the terminal
>voltage. Thus if you run it in gen mode at 1/5th rated speed you'll get
>most of 1/5th rated terminal voltage out.
>
>is that 15v ac single phase? If so, you need less. 14.4v is plenty to
>charge a12v lead acid, though I'm told 15v is nice for occasional
>equalisation. One can get 14.4 or 15 dc from what ac voltage?

No, it is a commutator motor, so it is DC.
>
>Rectifier drop = 2-3v for a silicon bridge rec, so we need an ac output
>with peak of 14.4+2.6 = 17v. RMS V = 17/1.414 = 12v ac.
>
>With 15v offload @ 600rpm, you'll get 12v offload @ 480rpm. And you'll
>get that onload at somewhere around 530rpm.
>
>You'd get that at slightly lower speed using a mechanical rectifier, if
>prepared to put up with one, since you could lose the rectifier V drop
>that way, but I'd have thought its still too fast to make a good
>windgen. You'd get significantly more mileage if you used a switch mode
>convertor, and using mechanical rectification on the input would
>increase output significantly.
>
>Although you could get current out for more of the cycle using a choke
>rectifier, the price is you'd have to run the gen significantly faster
>to get it.
>
>Any motor rated at thousands of rpm gives you an immediate problem.
>There are various ways round it to some extent, but a rewind would sure
>make life easier.

Except it is totally, 100% impossible to rewind a permanent magnet
electric motor with a printed circuit, ironless armature.
>
>
>NT

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meow2222@care2.com

2006-03-16, 9:21 pm

clare wrote:
> On 14 Mar 2006 13:35:38 -0800, meow2222@care2.com wrote:

>
> Except it is totally, 100% impossible to rewind a permanent magnet
> electric motor with a printed circuit, ironless armature.

Why can one not make a central wood piece and add 2 flat endpieces to
give the right depth of former, then wind new coils, adding glue to the
wire, then glue them to the pcb? Wrap the centre wood bit in polythene
first

clare at snyder.on.ca

2006-03-16, 9:21 pm

On 16 Mar 2006 16:45:48 -0800, meow2222@care2.com wrote:

>clare wrote:
>
>
>Why can one not make a central wood piece and add 2 flat endpieces to
>give the right depth of former, then wind new coils, adding glue to the
>wire, then glue them to the pcb? Wrap the centre wood bit in polythene
>first

>
>
>NT
The "armature" is 1/8 inch thick., and the commutator is also
"printed" on the face of the armature disk. Like I said ONE HUNDRED
PERCENT impossible to rewind!
Now, if you could triple the strength of the magnets?
Reducing the air gap might help a bit too, but it is already a pretty
small gap between the magnets and the disk.
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meow2222@care2.com

2006-03-18, 1:21 am

clare wrote:
> On 16 Mar 2006 16:45:48 -0800, meow2222@care2.com wrote:
[color=darkred]
[color=darkred]
[color=darkred]
[color=darkred]
> The "armature" is 1/8 inch thick., and the commutator is also
> "printed" on the face of the armature disk. Like I said ONE HUNDRED
> PERCENT impossible to rewind!

Ah I see, I was thinking of a different design, one with low profile
wire coils mounted on the pcb.

> Now, if you could triple the strength of the magnets?
> Reducing the air gap might help a bit too, but it is already a pretty
> small gap between the magnets and the disk.

Yes, a risky move.

Perhaps an external transformer might be an option if you need a given
V at lower rpm. A series capacitor can help unload it at low speed.
Switched mode transforming would be better though, as it can self
adjust to give best output across the speed range.

NT

clare at snyder.on.ca

2006-03-18, 3:21 pm

On 17 Mar 2006 20:53:19 -0800, meow2222@care2.com wrote:

>clare wrote:
>
>
>
>
>
>Ah I see, I was thinking of a different design, one with low profile
>wire coils mounted on the pcb.
>
>
>Yes, a risky move.
>
>Perhaps an external transformer might be an option if you need a given
>V at lower rpm. A series capacitor can help unload it at low speed.
>Switched mode transforming would be better though, as it can self
>adjust to give best output across the speed range.
>

I saw one apart yesterday. With a destroyed rotor. It is a glassfibre
sheet core with what COULD be described as low profile conductors
bonded to it.

The interesting thing is the magnets are NOT terribly strong, and they
have a shorted coil of wire wound in alternating directions around
easch magnet, IIRC about 3 turns each. The wire is not externally
connected to ANYTHING. The magnets are roughly 25mm (or one inch deep
and 35mm (or 1 3/8") diameter. Perhaps 1/4 (being generous here) as
strong as a hard drive magnet. More likely about 1/10th. They are
polarized end to end. I'm thinking put another coil on the magnets and
juice them real good once in a while to boost the magnets???
>
>NT

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meow2222@care2.com

2006-03-19, 9:21 pm

clare wrote:
> On 17 Mar 2006 20:53:19 -0800, meow2222@care2.com wrote:
[color=darkred]
[color=darkred]
> I saw one apart yesterday. With a destroyed rotor. It is a glassfibre
> sheet core with what COULD be described as low profile conductors
> bonded to it.

Are these conductors printed copper foil on the fibreglass pcb, or are
they round section copper wire coiled, and just a few turns high? Ya
know even with the former there might be some chance of doing something
if wanted, eg by layering on copper foil and paper. Wet varnish would
keep the paper weatherproof and bond it all together. Maybe there's no
room though.

> The interesting thing is the magnets are NOT terribly strong, and they
> have a shorted coil of wire wound in alternating directions around
> easch magnet, IIRC about 3 turns each. The wire is not externally
> connected to ANYTHING. The magnets are roughly 25mm (or one inch deep
> and 35mm (or 1 3/8") diameter. Perhaps 1/4 (being generous here) as
> strong as a hard drive magnet. More likely about 1/10th. They are
> polarized end to end. I'm thinking put another coil on the magnets and
> juice them real good once in a while to boost the magnets???

This sounds fairly different to whats in my mind: would it be
convenient to post a pic?

I'm no expert at magnetics, but I would have thought the material
limits the max mag firld it can produce, and that mfrs would get the
best out of their materials they can.

I've so little clarity on what exactly you've got that I dont know
whether it might be an option to add an energised field to the
permanent magnet field. Probably not, but who knows. If its possible
this might boost output a fair bit.

It might be easier just to use a switched mode convertor though

Just
that you'll never get as much power out if the genny output isnt
somehow boosted.

NT

clare at snyder.on.ca

2006-03-20, 1:21 am

On 19 Mar 2006 16:23:53 -0800, meow2222@care2.com wrote:

>clare wrote:
>
>
>
>Are these conductors printed copper foil on the fibreglass pcb, or are
>they round section copper wire coiled, and just a few turns high? Ya
>know even with the former there might be some chance of doing something
>if wanted, eg by layering on copper foil and paper. Wet varnish would
>keep the paper weatherproof and bond it all together. Maybe there's no
>room though.
They are a SUNGLE layer of flat conductor, bonded to, or printed on,
the fiberglass substrate. The conductors ARE the commutator, and there
is NO room for any more wire, even if it were possible to rewind it.
>
>
>
>This sounds fairly different to whats in my mind: would it be
>convenient to post a pic?
>
>I'm no expert at magnetics, but I would have thought the material
>limits the max mag firld it can produce, and that mfrs would get the
>best out of their materials they can.

You can take a soft iron core and have NO discernable magnetic field,
or you can stroke it with a magnet and make a half decent megnet out
of it, or you can wind a good coil around it, pour some amps into it,
and make a super powerfull magnet.
Using better steel, you can retain a fair amount of that magnetic
strength even with the juice cut off, or from the stroking.
Heat it or hit it, and youcan loose it all.

In an iron core motor, over-current in the armature can demagnetize
the fields. In an ironless rotor apparently this does not happen.

If I take one apart I'll post pictures. The one I saw apart was scrap
and I do not have it.
>
>I've so little clarity on what exactly you've got that I dont know
>whether it might be an option to add an energised field to the
>permanent magnet field. Probably not, but who knows. If its possible
>this might boost output a fair bit.
>
>It might be easier just to use a switched mode convertor though

Just
>that you'll never get as much power out if the genny output isnt
>somehow boosted.
>
>
>NT

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meow2222@care2.com

2006-03-23, 3:21 pm

clare wrote:
> On 19 Mar 2006 16:23:53 -0800, meow2222@care2.com wrote:

[color=darkred]
[color=darkred]
> They are a SUNGLE layer of flat conductor, bonded to, or printed on,
> the fiberglass substrate. The conductors ARE the commutator, and there
> is NO room for any more wire, even if it were possible to rewind it.

Sounds like a printed pcb, where the copper foil layer is etched to
produce the conductors. The only way I know to up the v from those is
to make a multilayer pcb, with the layers connected in series using
vias. A multilayer FR4 board isnt something easy to do at home, you'd
have to be a bit on the determined side, but not impossible.

A paperboard OTOH is makeable at home, using layers of copper foil,
paper and glue.

Or A duplicate FR4 pcb with thicker copper could perhaps produce more
i_out.

A switched mode convertor sounds a much easier prospect though, even if
a lot more limited in power than a rewind/reboard. Last time I was
involved with a very low v stepup we used germanium transistors, and
the finished article would power from, thinking, not sure but it was
below 0.5v.

Maybe gearing is a better option!

NT

clare at snyder.on.ca

2006-03-24, 1:21 pm

On 23 Mar 2006 11:15:06 -0800, meow2222@care2.com wrote:

>clare wrote:
>
>
>
>
>Sounds like a printed pcb, where the copper foil layer is etched to
>produce the conductors. The only way I know to up the v from those is
>to make a multilayer pcb, with the layers connected in series using
>vias. A multilayer FR4 board isnt something easy to do at home, you'd
>have to be a bit on the determined side, but not impossible.
>
>A paperboard OTOH is makeable at home, using layers of copper foil,
>paper and glue.
>
Except there is not enough gap to make the thing any thicker. And
taking them apart knocks the magnetic strength into the crapper. I
found out what the coil around the magnets is for. It's there for the
factory to jap with mega-amp mili-second pulse to get the magnets up
to strength after assembly. The "windings" on the rotor are bonded on,
not etched. I have a writeup on these motors I'll post to the web in a
couple of days.
>Or A duplicate FR4 pcb with thicker copper could perhaps produce more
>i_out.
>
>A switched mode convertor sounds a much easier prospect though, even if
>a lot more limited in power than a rewind/reboard. Last time I was
>involved with a very low v stepup we used germanium transistors, and
>the finished article would power from, thinking, not sure but it was
>below 0.5v.
>
>Maybe gearing is a better option!
>
>
>NT

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clare at snyder.on.ca

2006-03-24, 9:21 pm

On Fri, 24 Mar 2006 11:46:24 -0500, clare at snyder.on.ca wrote:

..
>Except there is not enough gap to make the thing any thicker. And
>taking them apart knocks the magnetic strength into the crapper. I
>found out what the coil around the magnets is for. It's there for the
>factory to jap with mega-amp mili-second pulse to get the magnets up
>to strength after assembly. The "windings" on the rotor are bonded on,
>not etched. I have a writeup on these motors I'll post to the web in a
>couple of days.

OK guys, for the curious among you, I put up the artical on my
web-site.

WWW.snyder.on.ca/pages/sg/How Printed Circuit electric motors work.doc

It explains things pretty well, with good pictures too.
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clare at snyder.on.ca

2006-03-24, 10:21 pm

On Fri, 24 Mar 2006 19:57:53 -0500, clare at snyder.on.ca wrote:

>On Fri, 24 Mar 2006 11:46:24 -0500, clare at snyder.on.ca wrote:
>
>
>.
>
>
>OK guys, for the curious among you, I put up the artical on my
>web-site.
>
>
>WWW.snyder.on.ca/pages/sg/How Printed Circuit electric motors work.doc

It will likely come up at something like 235% - scale it to 100% to
read it properly. You'll have to cut and paste, the whole URL doesn't
carry through for some reason.

>
>It explains things pretty well, with good pictures too.
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meow2222@care2.com

2006-03-26, 7:21 pm

clare wrote:
> On 23 Mar 2006 11:15:06 -0800, meow2222@care2.com wrote:

> Except there is not enough gap to make the thing any thicker.

Theres no need to make it thicker. More copper means less paper.

> And
> taking them apart knocks the magnetic strength into the crapper.

I dont see how

NT

clare at snyder.on.ca

2006-03-27, 12:21 am

On 26 Mar 2006 15:09:59 -0800, meow2222@care2.com wrote:

>clare wrote:
>
>
>Theres no need to make it thicker. More copper means less paper.

And there is no paper , and the fiberglass is not as thick as one
conductoe, muchless 2, which would be required to add any more copper.
>
>
>I dont see how
>
>
>NT

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meow2222@care2.com

2006-03-27, 1:21 pm

clare wrote:
> On 26 Mar 2006 15:09:59 -0800, meow2222@care2.com wrote:

>
> And there is no paper , and the fiberglass is not as thick as one
> conductoe, muchless 2, which would be required to add any more copper.

I guess electronics and gearing are your only options then. Or doing
nothing and just not getting much from it.

There is one other outer fringes approach that could work. Its a
mechanical switcher that connects to the output to one cell at a time,
and moves the connection from cell to cell every so often. When there's
enough V to charge one cell, theres enough V to run electronics, so in
principle its possible to look at the V_out and connect to whatever
number of cells it will charge at the time.

Switched mode electronics is of course easier, but will be very
inefficient at lower output. And it sounds like this machine will spend
a lot of its time in low output mode.

A 2 diode doubler rectifier would help, as theres only one diode V drop
in the rectifier, and the smpsu pass transistor sees nearly twice the
voltage, thus wastes half the percentage of power.

I suppose if you use no trnoics at all the 2 diode doubler would be
sensible. It would halve the minimum rotor speed required to charge.

NT

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