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niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331
Posted: 11:59am 19 Jun 2011
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hi Greenbelt
i,m not so good on non magnetic metals either .. thats an interesting stator idea there...
going back to your original thoughts on a large alternator this particular design is still in my head from when i first seen it ...
sounds daft..but i wonder if you could take a car or lorry axle, keep the wheel and cut off all the excess metal to leave one big true rotor to mount mags on ...its something that could only work for a vawt ....ish .. ...
ps...i got into the dummies section first...so theres no room for you..Edited by niall1 2011-06-20niall
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 02:20pm 19 Jun 2011
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Well Mac, an interesting way to build a better mousetrap you have here.
If you have a chance to see the innards of an ordinary AC stator have a good look at the way the laminated iron pokes through the center of the coils *but reminds behind them* everywhere else. There is always an air gap between the adjacent coil pole faces.
If I understand correctly, what you did it is to encase the coils completely with your magnetite mix. The magnetite that's in the center of the coils will assist but the magnetite elsewhere might prevent many of the flux lines from passing through the center of the coil.
Remember, the idea is to concentrate the flux passing through the center of the coil as the permanent magnet on the rotor passes by and have as good as possible a circuit path for the magnetic flux from the iron backing behind the coils.
Klaus
Greenbelt Guru Joined: 11/01/2009 Location: United StatesPosts: 566
Posted: 06:35pm 19 Jun 2011
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niall 1,
Niall wrote;
"i wonder if you could take a car or lorry axle, keep the wheel and cut off all the excess metal to leave one big true rotor to mount mags on ...its something that could only work for a vawt ....ish"
I don't see why not, if all the parts are placed correctly it shouldn't matter what is used to support the Mags. A Bicycle or Motorcycle wheel would be a strong support for a large diameter Alt.
Bike wheels of 20,-26, 28 inches diameter, Perfect size for a small Vawt. Lots of little mags Say 60, and run some test coils to see the path forward.
Gyroscopic forces on a Motorcycle wheel at speed when maneuvering would place a large axial force on the rim of the wheel, so you know that the spoked wheel is tough. ancient Autos used them also.
-------Cheers, RoeTime has proven that I am blind to the Obvious, some of the above may be True?
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 02:40am 20 Jun 2011
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Greenbelt,
Some of the very early cars and trucks had wooden spokes, not to mention all the frontier wagons...they all ran on wooden wheels. Mostly made from Hickory or Hard Maple, but I'd think just about any hard wood will do ok if a fella wanted to keep the magnets away from any steel or iron.
...Mac46
I'm just a farmer
MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329
Posted: 02:50am 20 Jun 2011
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[Quote=Tinker]The magnetite that's in the center of the coils will assist but the magnetite elsewhere might prevent many of the flux lines from passing through the center of the coil.
You may very well be correct here. I haven't spun the thing yet. I built this thing based on a "test coil" originally made for the tiny axial-flux machine, but after finding that I'd gone way beyond the practical size limitations, I decided to scrap that project and turn it into something that would actually provide enough energy for a "topping charge" on my land yacht batteries.
Remember, this core i "skein wound". That means it's just one ginormous coil. I used 30-gauge wire and there are 100 turns. I bundled the coil each inch or so to keep its shape while I wound the stator. The entire circumfrence of the coil is wound back and forth across the magnet pathway to form 12 crossings. That means each of the 12 neydymium magnets' flux pathways cut through 1,200 wires each revolution. That works out to 14,400 lines of flux whacked each revolution by all 12 magnets.
I know it will work, the question is how well. That remains to be seen. As I've stated elsewhere on the 4m, I gets a bit distracted with myself from time to time (read that constantly). I'll "Git-'R-Done" sooner or later and when that happens, I'll toss up a "build" post in Windmills.
Here's a snapshot of what I've got so far:
This will get "potted" in polyester (surfboard) resin that has had refined magnetite added to it to form a paste. If it retards the flux movement as you think it may, I'll use the mill and carve out the magnetite-filled spaces between things a bit in an attempt to overcome the bad effect (if any).
Gee, ain't this fun? Spend weeks and weeks designing and building stuff, then turn around an masacre it with your mill!
. . . . . MacNothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas
Greenbelt Guru Joined: 11/01/2009 Location: United StatesPosts: 566
Posted: 06:24am 20 Jun 2011
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Mac46,
Yes, Keeping the wooden spokes preserved may be a problem in some climates, western Washington is very destructive on anything made of wood. Normal Furniture in the home not included.
Time has proven that I am blind to the Obvious, some of the above may be True?
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 02:28pm 20 Jun 2011
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Mac, your definition of "skein wound" is vastly different from mine. I have actually wound 'skein' type coils - these are mainly used for starter windings in single phase asynchronous motors - when I studied that field during my trade tech time.
In my case the one big coil was folded over itself when inserted into the stator slots so it formed 3 complete nesting coils. All were within each other but in different field slots.
I would be very surprised if you get your idea to work at all. Remember, to induce a useful current in a coil it has to move past a magnetic field or vice verso.
In other words, the PM field lines go through the center of the coil or, in other words, the coil wire is wrapped *around* the PM field. Yours do not wrap around anything except the whole stator in a snaky fashion.
Yes you get an induced current by moving just a single wire through the PM field but to get a multiplying voltage effect that wire has to form a coil in the conventional definition.
But - go ahead and prove me wrong, I'd appreciate it. Never too old to learn something new Klaus
MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329
Posted: 05:13pm 20 Jun 2011
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Tinker
Okay, I'll proceede. For now, let's let it rest, cause we're basically hijacking this thread. I'll finish the build and post it along with the results good or bad. Look for it in "Windmills" sometime in the next few weeks.
. . . . . MacNothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 01:22am 22 Jun 2011
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Greenbelt, Glen, everyone,
I think that the one Glen is building will work if it can be enlarged to around 3 feet circumferance, more coils and more magnets, ect. Bigger shaft and bearings.
Its different than the one I was thinking about, but I think Glens will put out more power, and be easyer to build. I'm certainly no expert on these things.
...Mac46I'm just a farmer
Greenbelt Guru Joined: 11/01/2009 Location: United StatesPosts: 566
Posted: 02:23am 22 Jun 2011
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mac46,
The larger radius Alt. will have severe reactance, The torque needed to turn this Monster will be extreme, so care must be taken to size the Mags and coils to produce only the power that the mill can handle in normal wind. The Idea for the large radius is to produce some power in light wind where normally the mill would not turn with enough speed for Cut In voltage.
Did the Storm pass? and did you turn it loose ? we Need Input !---- Cheers, Roe Time has proven that I am blind to the Obvious, some of the above may be True?
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 03:13am 22 Jun 2011
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Greenbelt,
Yes the storm passed...and the other half is due here tonight. I had excellant wind today...but could'nt test the mill because of other things that "had" to be done. I did turn it loose yesterday but I had a wind shadow effect with the SE winds, I have 2 very large Maple trees directly up wind at approx. 125 feet distance. The winds were 5 to 10, so little available power. It did self start and started to spin up, then the wind changed and die'd off.
That is a very good observation and good point about sizeing the magnets and coils according to the capasity of the mill. I wanted to build my mill first for this reason...not knowing what if anything it was capable off. Very hard to get an accurate idea without building something like this first,and then testing the "bease wax" out of it.
You'r desine is appealing, and is what I was thinking of, right now I've got my eye on "alkindsastuff"...doing reading and studying when time permitts.
...Mac46I'm just a farmer
mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412
Posted: 01:11am 27 Nov 2011
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Greenbelt,
I've got my eye on some bar magnets...2x2x1 inches, $1.89 ea. and come in a box of 60 ct. They are regular magnets, not neo's. and I have enough 1/2" steel plate to cut a 3 foot circle. I'm thinking of starting on this project...More correctly I guess, I'm still thinking of starting on this project.
I could fit all 60 magnets in this 3" circle, thinking along the lines of a "dual" axual flux.
Regards,
Mac46
I'm just a farmer
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 02:44am 28 Nov 2011
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This is not strictly true.
As long as the moving magnetic lines cut through the wire at right angles, it will induce a voltage and a resultant current flow just fine.
A radio antenna is usually just a single straight piece of wire and does not meed to be wrapped around anything to work at both creating and receiving a moving (electro) magnetic field.
I had never heard the term "skein winding" before either.
But there is already US patent out for this type of electrical generating machine, using a petaled serpentine winding, so it definitely works...
http://www.patents.com/us-4357968.htmlEdited by Warpspeed 2011-11-29Cheers, Tony.
MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329
Posted: 03:39am 28 Nov 2011
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Warpspeed
Thanks for the interest. To the best of "my" knowledge (and I'm pretty electricity stupid) what I was attempting to build was a "skein" winding. In other words, I took one ginormous coil and wiggled it around such that I could cut different legs of the same coil with a concentrated magnetic field without creating any cancellation.
Did it work at all? No, but not because of anything electrical. What happened is when I spun things up using it as a "test coil" Murphy reached out and snagged a little piece of it. That's all it took and the rest was birdsnest soup!
I came into all this from a history of building tiny steam and air engines as well as R/C airplanes and the like. All the stuff I've built for the 4m and I do mean ALL of it has been too small. Even if I were to resurrect this project (which, by the way, isn't going to happen in this lifetime) it wouldn't be large enough to be of any practical use, but that's the way it is. I'm a sucker for small toys.
Now, my hunch is this post and this topic altogether is likely way off thread, so I'm just going to say thanks for everyone's input and put it to bed.
. . . . . MacNothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 05:49am 28 Nov 2011
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It certainly will work Mac, and it is a very clever and efficient design too.
Less total wire required means lower electrical resistance, no rats nest of internal soldered connections, and pretty straightforward to fabricate.
A crazy idea has just occurred to me.
Something like this could be printed onto a circuit board, even a multi layer circuit board.
That would make it very thin, typically only 1.6mm, which would allow a very small total air gap and increased magnetic field strength.
While the cost of getting one probably very large circuit board would be prohibitive, if a batch were ordered in reasonable quantity, the cost might work out quite reasonable (??).
This technique of using printed circuit coils is certainly not a new idea.
Planar transformers for switching power supplies often consist of multi layer windings on multiple circuit board layers, sandwiched between two very flat ferrite core halves. They can produce some pretty high currents too.
This creates a very low profile cheap to assemble transformer compatible with surface mount components.
A big flat circuit board with several layers, might make a pretty good axial flux alternator with this type of "Skein" winding technique used for the circuit board tracks, as there are no crossovers, and the track density could be quite high.
Here is a handy calculator for circuit board track width versus current, copper thickness and temperature rise.
http://circuitcalculator.com/wordpress/2006/01/31/pcb-trace- width-calculator/Edited by Warpspeed 2011-11-29Cheers, Tony.
retepsnikrep Senior Member Joined: 31/12/2007 Location: United KingdomPosts: 131
Posted: 01:40am 29 Nov 2011
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Now I think the pcb idea is brilliant.
The nature of pcb's would give identical coils and very nice reproduceability.
A Circular pcb is not an imposibility and a 2 layer board with coils on both sides connected by vias and a central power bus sounds very appealing. Use some thick copper traces and wide buses, hmm I want to build one now. Gen1 Honda Insights.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 02:12am 29 Nov 2011
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Computer mother boards, and many dense surface mount boards, with components on both sides, now routinely have seven or eleven layers of copper tracks internally.
And you can specify the copper thickness, one ounce per square foot of copper is the industry standard and most common thickness for most things. But half, two, and four ounce thick copper is available on request.
The circuit board manufactures build up a multi layer board one layer at a time,by gluing a flat copper sheet onto a fibreglass layer, etching it, then gluing another fibreglass layer on top, then another flat copper sheet, etching that, and so on....
So any number of layers could in theory be produced.
The final step is drilling right through all layers, and creating the plated through holes to link the internal layers, or bring them to the surface.
It sounds hugely complex, but in fact the PCB manufacturers now have robot assembly lines that can do all this at very competitive prices, particularly in China.
A simple home etched single or two layer board would make a great prototype for evaluation.
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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you have here.
