"print motor" servo as low speed generator??

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. *** Free account sponsored by SecureIX.com *** *** Encrypt your Internet usage with a free VPN account from http://www.SecureIX.com ***

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. *** Free account sponsored by SecureIX.com *** *** Encrypt your Internet usage with a free VPN account from http://www.SecureIX.com ***

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

On Sat, 11 Mar 2006 23:50:15 -0500, "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. *** Free account sponsored by SecureIX.com *** *** Encrypt your Internet usage with a free VPN account from http://www.SecureIX.com ***

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

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

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?

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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clare wrote:

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

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

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

clare wrote: On 14 Mar 2006 13:35:38 -0800, meow2222@care2.com wrote:
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.
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. *** Free account sponsored by SecureIX.com *** *** Encrypt your Internet usage with a free VPN account from http://www.SecureIX.com ***

clare wrote:

On 16 Mar 2006 16:45:48 -0800, meow2222@care2.com wrote: clare wrote: On 14 Mar 2006 13:35:38 -0800, meow2222@care2.com wrote:
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.
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 :)
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

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

clare wrote: On 16 Mar 2006 16:45:48 -0800, meow2222@care2.com wrote: clare wrote: On 14 Mar 2006 13:35:38 -0800, meow2222@care2.com wrote:
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.
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 :)
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.

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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clare wrote:

On 17 Mar 2006 20:53:19 -0800, meow2222@care2.com wrote: clare wrote: On 16 Mar 2006 16:45:48 -0800, meow2222@care2.com wrote: clare wrote: On 14 Mar 2006 13:35:38 -0800, meow2222@care2.com wrote:
Any motor rated at thousands of rpm gives you an immediate problem.
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

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

clare wrote: On 17 Mar 2006 20:53:19 -0800, meow2222@care2.com wrote: clare wrote: On 16 Mar 2006 16:45:48 -0800, meow2222@care2.com wrote: clare wrote: On 14 Mar 2006 13:35:38 -0800, meow2222@care2.com wrote:
Any motor rated at thousands of rpm gives you an immediate problem.
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. 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.

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.

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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clare wrote:

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

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

clare wrote: On 19 Mar 2006 16:23:53 -0800, meow2222@care2.com wrote:
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.
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.
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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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. *** Free account sponsored by SecureIX.com *** *** Encrypt your Internet usage with a free VPN account from http://www.SecureIX.com ***