| Post Info | TOPIC: large diameter alternator |
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Lynx Steam
Senior Member
Posts: 279
Date: May 28th
| RE: large diameter alternator |
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| Really what I am proposing in essence is this: Two stator plates side by side each with 15 coils, but in this large diameter design each coil is flipped N-S 40 times per revolution. Your idea is to lay them on top of each other and have 30 of each coil, just thinner, and 40 flux changes per rev. To me it seems about the same, except that your idea may give the thin wire coils a little less flux. What I am discovering through experimentation is that a beefy alternator is great in winds over 20 mph, but under that nothing much. Takes rpms to generate voltage in that big wire. A meager and thin wired alternator is great in low winds but the resistance kills it when the winds pick up. I also think VAWTs need the different approach of a large diameter alternator. Using a Hawt alternator is wrong. At low rpm the Vawt can take advantage of more flux changes with a big diameter alternator. Then it is also important to make sure the VAWT has good strong torque at the lower rpm. The hawt gets its torque from speed, the Vawt from grabbing the wind. I'll draw up the circuitry for the power switch over relay I am thinking of. I think it will be important to de-energize the low wind coils at higher rpm. I have drawn several circuit systems and have concluded the simplest is best. Just a light coil sixer that kicks over to a heavy coil Star somewhere near 110 rpm.
Marcus |
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sjh7132
Guru
Posts: 1252
Date: May 27th
| large diameter alternator |
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| Caleb wrote:
I was thinking of doing something like that winding a coil with a tap near the center. Then if both the end of the coil and the tap were run to separate rectifiers, current would feed through the rectifier with more turns until the rectifier connected to the tap wire could conduct. One problem I ran into analysing the design was that the upper turns would conduct even when the tap rectifier was active. To make the design more efficient, there should be a way to turn off the upper turns and just let the tap conduct in higher winds. Perhaps if there were a MOSFET switch after the rectifier connected to the coil end, it could gradually shift current to the tap using a PWM signal. (I was thinking of using smaller wire for the upper part of the coil to limit the space used ... perhaps winding 3 or 4 in hand up to the tap point, soldering the wires together and finishing the coil with a single strand of wire.)
That could work. It's also possible that if the upper layer was the right thickness, it would be enough to transfer a few watts in low winds (which is all you get in low winds), but in high winds the resistance would limit the power it could transfer. Or like you suggested a MOSFET circuit. But it would need some positive feedback so that it 'flipped' on and off quickly. (Or PWM, but then you are talking about a control circuit and at that point it's only a few steps to a peak power tracking controller.) -- Edited by sjh7132 on Thursday 27th of May 2010 11:18:35 PM
Steve
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Caleb
Senior Member
Posts: 473
Date: May 27th
| RE: large diameter alternator |
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| sjh7132 wrote:
Lynx Steam wrote:
What I would do without your circuit expertise would cost about $45 and I know it would work while it is rather simple. I think, I would skip the trippler and just go with star parallel or switch to pure 3 phase parallel at really high rpm.
I can't make a peak power point tracking controller for $45.00. (yet) I was just looking at an IC that does it for Solar, but it was limited to 2 amps.
How about a simpler approach???? Wind your main coils in the primary realestate, right next to all the magnets, and wind a second batch of coils with much thinner wire on top of them where they don't get the best field. Wind enough turns of that thinner wire to get a few watts for low winds, and it's resistance will limit it in higher winds. (Maybe this was your original plan and I'm just understanding it.)
(Once you get a measurement of your magnets with a test coil, you can figure out turns and wires sizes with a spread sheet.)
I was thinking of doing something like that winding a coil with a tap near the center. Then if both the end of the coil and the tap were run to separate rectifiers, current would feed through the rectifier with more turns until the rectifier connected to the tap wire could conduct. One problem I ran into analysing the design was that the upper turns would conduct even when the tap rectifier was active. To make the design more efficient, there should be a way to turn off the upper turns and just let the tap conduct in higher winds. Perhaps if there were a MOSFET switch after the rectifier connected to the coil end, it could gradually shift current to the tap using a PWM signal. (I was thinking of using smaller wire for the upper part of the coil to limit the space used ... perhaps winding 3 or 4 in hand up to the tap point, soldering the wires together and finishing the coil with a single strand of wire.)
- Bryan
Mechanical Engineer turned stay-at-home dad. |
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sjh7132
Guru
Posts: 1252
Date: May 27th
| RE: large diameter alternator |
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| Lynx Steam wrote:
What I would do without your circuit expertise would cost about $45 and I know it would work while it is rather simple. I think, I would skip the trippler and just go with star parallel or switch to pure 3 phase parallel at really high rpm.
I can't make a peak power point tracking controller for $45.00. (yet) I was just looking at an IC that does it for Solar, but it was limited to 2 amps. How about a simpler approach???? Wind your main coils in the primary realestate, right next to all the magnets, and wind a second batch of coils with much thinner wire on top of them where they don't get the best field. Wind enough turns of that thinner wire to get a few watts for low winds, and it's resistance will limit it in higher winds. (Maybe this was your original plan and I'm just understanding it.) (Once you get a measurement of your magnets with a test coil, you can figure out turns and wires sizes with a spread sheet.)
Steve
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Lynx Steam
Senior Member
Posts: 279
Date: May 27th
| RE: large diameter alternator |
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| Thanks for the feedback. When I go to 2" x 1" rectangles the geometry changes of course. I can get 30 coils and 40 magnets inside a 2' circle. I thought about filling a 3' circle but that would be too much copper and magnets. I would need 45 coils and 60 magnets. At a certain point the alternator overpowers the VAWT. Which leads me back to the idea of placing some coils in with thinner wire. At low wind speeds these wont kill the rotation. At higher wind speeds, who knows what I can do with all these coils. I am also thinking the 1/2" thick magnets again may overpower the VAWT. There are 1/8" thick magnets with 26 LB pull. Really all I am after is a way to do useful work in all wind-speeds, and the only way I know to achieve this is with more coils and thinner wire. But, this alone would limit the output at high wind speeds. I have the wire already. Its about $120 worth. The magnets are about $80. Now, tell me more about the circuitry you would recommend. The link you gave me was dead. What I would do without your circuit expertise would cost about $45 and I know it would work while it is rather simple. I think, I would skip the trippler and just go with star parallel or switch to pure 3 phase parallel at really high rpm.
Marcus |
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sjh7132
Guru
Posts: 1252
Date: May 27th
| RE: large diameter alternator |
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| Lynx Steam wrote:
Lets put the round vs rectangle aside for a minute. I can easily make the coils slightly wedge shaped and use rectangular magnets. What do you guys think about the idea of two sets of coils. One set heavier gauge, and one set lighter gauge? The idea being to get ultra low wind trickle charge and provide for capturing the power in heavier winds. I will experiment with the relays and adjusting their automatic operation, but I assume this can be accomplished.
It seems that in an alternator, the one critical resource is the space for wire in the areas where the magnets will create a field. I like your idea, but hate that you are sacraficing space for your main coils for the Sixer coils. There is a circuit called a Kirchoff ladder, which is similar to the Sixer, but a chain that you can replicate to get 4x,6x,8x,10x, etc voltage multiplication. This circuit is nice because it doesn't force you to connect your phases in series. I believe you could use a Kirchoff ladder and your normal rectifiers on your main coils (wired in star) at the same time. Like the Sixer, the ladder will only transfer a limited amount of power at a given RPM, so the cap sizes could be tuned so that at low wind speeds it does some charging, but at higher wind speeds the ladder only takes a few watts (which still go into the battery), but the main circuit handles most of the power. Before you implement anything, add up the parts cost. It may end up that my peak power tracking charge controller circuit may be more cost effective.
Steve
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Lynx Steam
Senior Member
Posts: 279
Date: May 27th
| RE: large diameter alternator |
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| Lets put the round vs rectangle aside for a minute. I can easily make the coils slightly wedge shaped and use rectangular magnets. What do you guys think about the idea of two sets of coils. One set heavier gauge, and one set lighter gauge? The idea being to get ultra low wind trickle charge and provide for capturing the power in heavier winds. I will experiment with the relays and adjusting their automatic operation, but I assume this can be accomplished.
Marcus |
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Bernd
Senior Member
Posts: 233
Date: May 26th
| large diameter alternator |
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At ironless Generators the induction directly goes into the wire, not into the core of the coil like it does at iron core coils.
At ironless Generators there is no induction into the coil.
The induction has it lowest value when the magnet stands directly over the hole of the coil.
Thats completly opposite to iron systems.
The indcution of a ironless has it highest point when the magnet cross the wire leg at 90 degree.
Thats the point why round coils are at ironless alternators not effective because the lowest part of the flux crosses the wire at the round coil with 90 Degree.
Much better are square coils and magnets, best not square but rectangular with long coils legs. So you get a long part with full induction and a low part without.
Bernd
-- Edited by Bernd on Wednesday 26th of May 2010 09:54:23 PM
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sjh7132
Guru
Posts: 1252
Date: May 26th
| RE: large diameter alternator |
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| Bernd wrote:
Marcus round coils and magnets are not very effective at ironless alternators.
Better you use square coils and magnets.
Bernd, why is that? It seems that round gives you the most area for the least amount of wire. Do the field lines spread faster or something?
Steve
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Bernd
Senior Member
Posts: 233
Date: May 26th
| RE: large diameter alternator |
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Marcus round coils and magnets are not very effective at ironless alternators.
Better you use square coils and magnets.
Bernd
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DESIGNS RIDES
Member
Posts: 13
Date: May 26th
| RE: large diameter alternator |
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I had thought about different cutins at different rpm's also. My theory was since I have 6 banks of coils to switch on or off I could switch on various banks of coils at different rpm's.
I thought that by adding banks of coils at higher rpm's the blades of the vawt
would not be over whelmed from the begining. Hence low wind speed less power or torque, then maybe as wind speed increases switch on addtional banks of coils, so as not to over power the vawt with the alternator. As it is with the one bank under load I can still turn it by hand easily.
THANKS MIKE
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Lynx Steam
Senior Member
Posts: 279
Date: May 26th
| large diameter alternator |
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| This is a good thread. Here's a drawing of what I am thinking. Its a three tiered system, pma alternator. 30 coils total, but half of them are thinner gauge wire and are led off to a voltage sixer for really low rpm charge voltage. The next step is a coil group of heavier  gauge wire coils led to a voltage tripler that can be switched automatically to star at higher rpm. I am thinking that switching could be as simple as 12 vdc relays that sense voltage from the next step up, using diode drops to adjust cutin. So when the heavier gauge wire coils reach 13.5 vdc the relay is closed and the lower rpm system is de-energized. When the voltage trippler reaches a certain amperage a set of three relays cuts out the trippler and opens the star circuit. The sixer is a light load, the trippler a medium load and the star a heavy load. So maybe we can utilize light breeze all the way up to heavy winds without stalling the VAWT. Low rpm - sixer mid rpm - trippler high rpm - star -- Edited by Lynx Steam on Wednesday 26th of May 2010 05:32:22 PM
Marcus |
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keithturtle
Senior Member
Posts: 174
Date: May 3rd
| RE: large diameter alternator |
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| Apparently the large-diameter alternator idea has a future http://www.earthtronics.com/honeywell.aspxLooks to be coreless axial-flux on the perimeter, well-placed spokes keep it true to the stator Turtle
Soli Deo Gloria |
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DESIGNS RIDES
Member
Posts: 13
Date: April 15th
| RE: large diameter alternator |
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| Sorry guys,
I've been extremely busy for the past month. This is my busy time of the year and have been putting in the over time. I get off worK, eat some fast food and go to work on mom's house, as we have to get it sold. I get home some time after midnite, just to it all over the next day. I'm missing out on some good wind as we had 25-30mph with gusts over 50 for the last two days.
A coworker and friend gave me something that MIGHT BE OF INTEREST to some of you. Also need your help INDENTIFYING IT.
Will try to get some pictures of it posted soon.
THANKS, MIKE |
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keithturtle
Senior Member
Posts: 174
Date: Mar 2, 2010
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DESIGNS RIDES
Member
Posts: 13
Date: Mar 1, 2010
| RE: large diameter alternator |
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| E-dady, thanks for the kind words. The spokes serve two purposes. First to keep the weight to a minimum, and second it allows me to true the magnet rotor. I have tuned the rotor to within a few thousands. There are 90 spokes alternating top and bottom. they are just straight, and not laced together like a bike wheel. The rotor is actually T shaped though hard to tell from the pictures. The material I used for my mill is .063 alum sheet then broke in to shape. I may be losing some air in the scoops due to the open ends, but with the snow we have here in Colorado I thought this way there would not be any problems with ice making it out of balance. On my working mill I'll probably use .50 alum and roll the scoops so as not to have the brake lines disrupting the air flow on the upwind side. I had thought about useing magnets on each side of the rotor rim, but due to cost thought it would still work this way. Useing the laser to cut the rim allowed me to get the spacing exact. I fabricated a jig out of alum to set each magnet for depth in the rotor. I will run a femm simulation to see just how much difference it makes. THANKS AGIAN !!! MIKE |
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electrondady1
Senior Member
Posts: 430
Date: Feb 28, 2010
| large diameter alternator |
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yikes!
you are a skilled and imaginative builder.
love the spokes
love the" L"shaped rotor.
like the way you were able to build your lenze2 with no web supports
by using a thicker material .
hate the way you embedded the magnets in metal
if you placed the same magnets on the steel you will produce twice the flux density and make use of half the copper .
cutting your total resistance in half .(hello amperage!)
-- Edited by electrondady1 on Sunday 28th of February 2010 05:00:17 PM
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DESIGNS RIDES
Member
Posts: 13
Date: Feb 28, 2010
| RE: large diameter alternator |
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| The magnets are oriented N-S-N-S . The coils are sized such one leg is over a north pole and the other leg is over the south pole . There are three coils in a set each overlapping and then repeating . Such as A-B-C, A-B-C, A-B-C etc. until there is 15 sets of three in each bank. There will be three banks of fortyfive coils above the magnets and three banks of fortyfive coils below the magnets. This amounts to 135 coils on each side, resulting in 270 coils total. |
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sjh7132
Guru
Posts: 1252
Date: Feb 28, 2010
| RE: large diameter alternator |
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What is the pattern you are following? It almost looks like a coil circles 3 magnets. I think that would be self defeating, unless you have the magnets oriented so that there are 3 norths, then 3 souths, then 3 norths.....
__________________
Steve
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DESIGNS RIDES
Member
Posts: 13
Date: Feb 27, 2010
| RE: large diameter alternator |
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| Just a couple more because I don't want to put my kid through any more...
Bank number 2 half finished, but hopefully shows how the coils are layed out.
Close up of coils.
I know there will be a lot of questions but I will answer them asap.
Thanks Mike and Kaitlyn :D |
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DESIGNS RIDES
Member
Posts: 13
Date: Feb 27, 2010
| RE: large diameter alternator |
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DESIGNS RIDES
Member
Posts: 13
Date: Feb 27, 2010
| RE: large diameter alternator |
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| I used my daughter's cell phone to take some pic's. I hope that I can figure out how to attach them , so here goes .  My prototype mill, it's a modified lenz 2  The magnet rotor, 32 inches, center of mags  Close up of mags Thanks so much to my devoted daughter, Kaitlyn, that did all of this for me :D |
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vawtman
Senior Member
Posts: 251
Date: Feb 27, 2010
| RE: large diameter alternator |
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Mike are you running this has an aircore or do you have return path?
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vawtman
Senior Member
Posts: 251
Date: Feb 27, 2010
| RE: large diameter alternator |
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Yepper Steve :)
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DESIGNS RIDES
Member
Posts: 13
Date: Feb 27, 2010
| RE: large diameter alternator |
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| Hi guys, I got the idea for the big dia. alt from my limited machineing experince. larger dia. materials have to turn a a slower rpm due to surface speed. I put 2 and 2 together and started to realize what sjh7132 said. It's been fun and a lot of work.
I made a mistake earlier when I said my mags were .375 thick , they are actually .5. I have acess to a laser cutter at work so have the benefit of haveing my parts cut with accuracy. Believe me I would not been able to do this with out it. The one I'm finishing is my third attempt. I have the mag rotor finished and one and a half banks of coils done. I have tested the first bank useing a 60 rpm gear motor to turn the rotor. After wireing the coils together and rectifing the phases I'm getting 18 volts dc at 60 rpm. I do not have an amp meter yet so can't measure the amps. I tried to attach a autocad drawing to my last post, but it would not accept it. I will try to change the format and post drawings monday. THANKS MIKE. |
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sjh7132
Guru
Posts: 1252
Date: Feb 27, 2010
| RE: large diameter alternator |
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If you want to build a very powerful and efficient alt, the large diameter is the way to do it. It pays off in two ways. 1) You get more change in flux per rev due to more magnets, and 2) You get more total flux through the coils with less wire do to more magnets. So for twice the diameter, you get 4x the power per RPM.
__________________
Steve
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vawtman
Senior Member
Posts: 251
Date: Feb 27, 2010
| RE: large diameter alternator |
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Hi Mike
COOL! Pics please
My early experiments were with geared motor conversions and since my blades had no cups to help bust through cog and gearing i had to come with a better plan.
The overall weight of the rotor(70 lbs)i think will stabilize the turbine in unstable winds.
Has my bud Edaddy stated i'm havin trouble designing the stator.One thought would be a wave winding with heavy wire or just a few coils stratigically placed to reduce vibration.
The 108cl setup was too flimsy but learned from it.
Last year was pretty much smoked(lol) on learning and growin tobacco.Will be back this year though.
Be carefull not to run it over 600v though :)
Have fun
Mark
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Zapmk
Veteran Member
Posts: 49
Date: Feb 26, 2010
| RE: large diameter alternator |
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Hello Mike,
32 inch yep that a big one all right, looking forward to seeing the pic's and dwg's
I've been working on a 24 inch dual rotor 32 pole 24 coils 3 phase, after 4 years of
working on it off and on it's getting closer to flying.
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electrondady1
Senior Member
Posts: 430
Date: Feb 26, 2010
| RE: large diameter alternator |
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a diagram would be fine for an understanding of what you have.
it sounds interesting .
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DESIGNS RIDES
Member
Posts: 13
Date: Feb 26, 2010
| RE: large diameter alternator |
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I'll try to answer some of your questions and if i can i'll post some dwg's and pic's as soon as i can.
The alternator has a single magnet rotor and 6 banks of 45 coils, 3 banks of coils above and 3 banks below. I'll try to post some dwg's and pic's as soon as i can.
In my craziness i started on this long before I found this and other forums, but decided to continue as my reasoning seems sound. Vawts as we all know are for the most part , slow in the rpm's ,but strong in thier torque and power. so in that line of thinking i decided that to increase speed or at least the speed that a magnet passes a coil, a large diameter alternator would be better. most axial flux alt's shown on the net are 9 coils and 12 magnets, at 10 rpm that means that a magnet crosses a coil 1080 times in that minute. in a larger diameter alt with more mags and more coils that increases , case in point I have 90 magnets and 270 coils so at 10 rpm I get 243 thousand times that a magnet crosses a coil per minute. the idea is that what creates the electricity is the mag crossing the coil so the more times you can do that the better off you are. so I decided to go as large as possible, hence this altenator.
Electron I plan to stack two lenz type turbines on top of each other rotated 90 degrees to smooth out the rotation and get more power to the alt.
I consider vawtman my inspiration also. as when I found this forum and some others i got quite discouraged till I seen his monster ALT.
THANKS MIKE
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electrondady1
Senior Member
Posts: 430
Date: Feb 26, 2010
| RE: large diameter alternator |
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sounds like three single phases to me .
that's a nice way to go.
is the stator one piece ?
the largest dia alt i have done is 14" but that was with ceramic mags.
i have 48, 1"x2"x.5" n42 mags siting on my shelf for about two years now
waiting for my new shop to be finished so i can build a decent size windmill
i am of two minds still as to lay out.
a dual rotor axial with 24 and 24 or a radial with 48 poles .
and of course now bernd has pointed the way to this new ironless single rotor design
decisions decisions .
i consider vman a friend , we used to chat a lot over at otherpower.
his 54 pole radial has huge potential but i don't think he ever finished the stator.
so you are stacking a second lenze2 to get more torque?
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Bernd
Senior Member
Posts: 233
Date: Feb 26, 2010
| RE: large diameter alternator |
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Hello Mike,
I'm working on a Generator with 60cm magnet plate diameter.
You use 270 Coils for only 90 magnets ?
Did you build a ironless axial flux plate generator ?
What is the reason to use so much coils ?
Normaly you use 1/4 less coils than magnet poles for 3 phase.
Do you have some pictures of your big Generaor ?
Bernd
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DESIGNS RIDES
Member
Posts: 13
Date: Feb 26, 2010
| large diameter alternator |
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| Hello all, i've been a member since sept. and a follower for alot longer.
My question is has anyone here ever built a large diameter alternator?
or should i say anyone besides the famous Vawtman with his VAWTINATOR.
I've been working on a 32" diameter alternator for around a year,off and on.
It has 90 mags and 270 coils. the mags are .75dia. x .375 thick n40's.
My coils are 20 gauge wire with 40 turns, 3 phase. I built a version of the lenz2
vawt. it's 40" diameter x 48 tall. I've gotplans to double the hieght on the one thatpowers my alternator. Seems that here we've got wind from 5-10 mph. most days, and days of 30 plus mph a lot. seen gusts over 60 . my prototype lenz has withstood it all. Guess that's why there is over 500 of the big boys just 20 miles from here. Thanks to all for the motivation, inspiration and INFORMATION. MIKE |
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