Author Topic: stacked coils idea, would it work?  (Read 2010 times)

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iFred

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stacked coils idea, would it work?
« on: July 01, 2004, 09:36:23 PM »



Stacked coils idea, with this idea I figure you could fit hundreds of coils one next to the nex one in stacked formation, each coil sees a north pole and a south... Thoughts?? Would it work?? The only problem seems to be the air gap.....

« Last Edit: July 01, 2004, 09:36:23 PM by (unknown) »

stop4stuff

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Re: stacked coils idea, would it work?
« Reply #1 on: July 02, 2004, 12:44:39 AM »
Hi iFred,


i was going to say it wouldn't work, but on thinking about it, I'm not so sure.

Bigger magnets, squash the coils coils and who knows.

Perhaps the answer is waiting to be discovered?


paul

« Last Edit: July 02, 2004, 12:44:39 AM by (unknown) »

Virgis

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Re: stacked coils idea, would it work?
« Reply #2 on: July 02, 2004, 02:49:51 AM »
Hi, iFred

it will not work.

the magnetic flux is crossing in one direction both legs (top and buttom) of coil and you will have zero. It is possible to have voltage if your coil will be wounded like figure 8.

Regards

Virgis
« Last Edit: July 02, 2004, 02:49:51 AM by (unknown) »

Gary D

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Re: stacked coils idea, would it work?
« Reply #3 on: July 02, 2004, 05:52:27 AM »
Hi Fred, I think down a few posts Devon(?) was asking the same thing in (3 or more phases). If you would purposly put your magnets out of alignment a bit, I do wonder (one disc slightly out of sinc but the same ammount of magnets). Just a thought from a dummy, not worth 2 cents! Gary D.
« Last Edit: July 02, 2004, 05:52:27 AM by (unknown) »

Junkie

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Re: stacked coils idea, would it work?
« Reply #4 on: July 02, 2004, 06:09:02 AM »
I don't think that will work. But I found this image on this site. Its a bit similar I think


See:


http://www.otherpower.com/images/scimages/83/ToroidalStator_crosssecviewa.jpg

http://www.otherpower.com/images/scimages/83/ToroidalStator_statorviewa.jpg


I'm pretty sure this would work(dont know how well), I even made a little test coil to see and I got around 4VDC at 2600Rpm on my bench drill. This was using 6  1inch ceramic speaker magnets. I didn't measure the current.


NOTE: I didn't draw those images above. I don't know who did.

« Last Edit: July 02, 2004, 06:09:02 AM by (unknown) »

windstuffnow

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Re: stacked coils idea, would it work?
« Reply #5 on: July 02, 2004, 08:11:16 AM »
  It's a neat idea iFred, unfortunately it doesn't work.  If you follow the magnetic circuit you'll find that each pair makes up one pole and the return path is the next pair beside it.  As you have it in the drawing, both legs of each coil are only seeing one pole.  If you turn the coils so one leg is seeing one pair and the other leg is seeing the other pair then it will work.   I think Electric Ed has posted some good drawings showing the overlapped coils under a dual rotor system.


   At the point of total frustration, your mind is working the hardest to find an answer.  The answer is there, you simply need to ask the right question.  Is it the answer we are really looking for... or is it the right question?


   Keep going... your close to something new!


Have Fun

Windstuff Ed

« Last Edit: July 02, 2004, 08:11:16 AM by (unknown) »
Windstuff Ed

iFred

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Re: stacked coils idea, would it work?
« Reply #6 on: July 02, 2004, 01:37:12 PM »



OK, what about this then!

« Last Edit: July 02, 2004, 01:37:12 PM by (unknown) »

Devo

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Re: stacked coils idea, would it work?
« Reply #7 on: July 02, 2004, 04:53:37 PM »
I have been thinking the same way :-) , Wish I could figure how to draw it like that - good job.


Devo

« Last Edit: July 02, 2004, 04:53:37 PM by (unknown) »

windstuffnow

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Re: stacked coils idea, would it work?
« Reply #8 on: July 02, 2004, 08:30:20 PM »
  iFred,  that almost looks like it might work.  Probably the slanted version.  I'm not sure you'd get the full potential of what it could in another configuration.  It's a slick idea though and would be worthy of a small prototype.  Possibly set it up with alternating poles on both discs to take advantage of all the wire, all the time.


Have Fun

Windstuff Ed

« Last Edit: July 02, 2004, 08:30:20 PM by (unknown) »
Windstuff Ed

elvin1949

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Re: stacked coils idea, would it work?
« Reply #9 on: July 03, 2004, 04:39:27 AM »
hi fred

i agree with ed

slanted looks good

the angle will be the key i think

later

elvin
« Last Edit: July 03, 2004, 04:39:27 AM by (unknown) »

devoncloud

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Re: stacked coils idea, would it work?
« Reply #10 on: July 04, 2004, 03:26:26 AM »
Well, to clarify, my idea of the stacked coils was not quite what internet fred has here.... my idea was to stack coils very much like ed (windstuffnow)has been, except he knows what he is doing and I really don't :).  


My idea (which I might not have been so good at clarifying in writting) was to stack coils diagonally a little so that you could utilize the space in the middle of a coil.  In other words, say you have a twelve coil stator.  My idea was to make more sets of of twelve coils and offsetting the legs of each set of coils from the other a little so that the legs uitlize all the space in the stator instead of having a big hole of unused space in the middle of each coil.  My idea was to create three or four (however much room was available) "layers" of twelve coils, and then rectify the different layers as if they were seperate from one another.  This would have turned my twelve coil stator into a 36 coil stator (if three layers of coils is what worked, 48 coils if four layers fit)or three seperate twelve coil stators but all in the same mold.  I was also thinking making one of the layers into a smaller size wire for better start up speed, however have thought better of the idea since I have no idea how I would be able to turn that layer off in higher wind speeds and so it would overheat and ruin my stator.


Ed has been doing something very similar to my idea it seems (not to mention he has actually done it while I have just had the idea floating around in my head), except he stacks to legs of his coils in one "slot" on each of his layers, which is not what I had in mind but seems to work great and would maximise the usage of space even more than what I had in mind.  

Devon

« Last Edit: July 04, 2004, 03:26:26 AM by (unknown) »

Ungrounded Lightning Rod

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Re: stacked coils idea, would it work?
« Reply #11 on: July 04, 2004, 04:56:45 PM »



  1. My idea (which I might not have been so good at clarifying in writting) was to stack coils diagonally a little so that you could utilize the space in the middle of a coil.  In other words, say you have a twelve coil stator.
  2. My idea was to make more sets of of twelve coils and offsetting the legs of each set of coils from the other a little so that the legs uitlize all the space in the stator instead of having a big hole of unused space in the middle of each coil.
  3. My idea was to create three or four (however much room was available) "layers" of twelve coils, and then rectify the different layers as if they were seperate from one another.


If I understand the descriptions correctly:


 1. involves coils that (in a three-phase example) look roughly like this from the end:


 * * * * *

/ / / / /

 
/ / / / /

* * * * * *

 but flattened top-to-bottom by a bunch (so the runs in-out of the screen are in the same position right-to-left but the slope of the slashes is closer to horizontal.)


 3. involves making an N-layer "cake" and rotating each layer by 1/N coil width, like this:


-
 --  --  --

  --  --  --

--  --  --  -


These are equivalent and both will work quite well.  (Unlike iFred's straight-up version and its variants.)  The upside is that you've increased the amount of copper that gets "cut" by the magnetic field, generating more power.  The downside is that you've increased the gap between the magnets, weakening the field and losing part of your gain.


What will improve them even more is to bend the part of the coil that is NOT between the poles of the magnets, so that the part BETWEEN the magnets can lie completely flat, lining up that part of the coils.  This lets you leave the gap minimal and the field strong.  So you get the gain without the loss.


(I won't attempt a typewriter picture of 1, where each slash turns into a lazy S.)  Here's a rendering of 3.:


  +--+  +--+  +--+

  |  |  |  |  |  |

 +--+| +--+| +--+| +

 || || || || || || |

*
******

|  |  |  |  |  |  |

+--+  +--+  +--+  +-


That just converged on windstuffnow's Dual rotor stator.


Three phases are about as many as you need to pull this off.  More phases just means more rectifiers and interconnection but no more power, since you can put the same amount of copper under the magnets with three.


However, you can increase your flux further by leaving a gap between the windings and putting a flux path between the magnets in the space between them.  In this case what you want to do is "pave" the area mostly with flux-path metal.  The gap that controls the flux penetration is the sum of the gaps between the flux-path metal and the rotor magnets, not that between the rotors, and you can make that quite small.  The flux has to jump through the coil to get to the next path, so you pretty much aren't penalized for making your coils thicker and the individual windings narrower to get the same amount of copper cut.  You DO need to make the coil slots wide enough that the flux doesn't jump over the coil to the next flux-path rahter than going through to the other rotor, and this limits how much of the area you can "pave" with flux path metal.


If you DO pull that, you need to laminate the metal, oriented so the moving field is "sliding along" the laminations rather than crossing them.  Otherwise you'll get a current in the (somewhat resistive) flux-path metal and that will both steal some of your generated current from the coils and produce a lot of heat.  (You'll still get a little in a laminated structure, though far less than in a solid block.)


The limit to your total output current your genny produces is the amount that it would take, moving in loops through your stator (or some solid-conductor replacement of it), to generate the same magnetic field as is produced by your rotor magnets.  You can divide that current by any number of turns (multiplying the voltage by the same factor because the turns are series), but you can't raise it by using thicker copper.  Spinning faster still raises the voltage (as long as you don't suck it down by pulling too much current, which would then limit the number of turns the field penetrated as it went by).

« Last Edit: July 04, 2004, 04:56:45 PM by (unknown) »

Ungrounded Lightning Rod

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Re: stacked coils idea, would it work?
« Reply #12 on: July 04, 2004, 05:16:23 PM »
Argh!  I hit "post" instead of "preview" and the editor ate my typewriter pictures.

Let's try this:


= = = =


 1. involves coils that (in a three-phase example) look roughly like this from the end (with x where it goes "into" the screen, o where it comes "out"):


 o o o o o o  

/ / / / / /  

 / / / / / /  

x x x x x x  


= = = =


 3. involves making an N-layer "cake" and rotating each layer by 1/N coil width, like this:


-o  x--o  x--o  x--o  

  x--o  x--o  x--o    

x--o  x--o  x--o  x-  


= = = =


(I won't attempt a typewriter picture of 1, where each slash turns into a lazy S.)  Here's a rendering of 3.:


  +--+  +--+  +--+  

  |  |  |  |  |  |  

-+| +--+| +--+| +--+

 || || || || || || |

xoxoxoxoxoxoxoxoxoxo

|  |  |  |  |  |  |  

+--+  +--+  +--+  +-

« Last Edit: July 04, 2004, 05:16:23 PM by (unknown) »

devoncloud

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Re: stacked coils idea, would it work?
« Reply #13 on: July 05, 2004, 01:41:29 AM »
1. "Three phases are about as many as you need to pull this off.  More phases just means more rectifiers and interconnection but no more power, since you can put the same amount of copper under the magnets with three."


Correct me if I am wrong, but part of what makes Windstuffnow's design work so well is the little amount of turns per coil.  In his last example he made ten turns per coil, and is contemplating wether or not he should have only have made eight turns if I remember correctly... I would venture to guess that by doing so decreases the amount of resistance.  By making more layers of coils with less turns, are you not decreasing resistance per coil and thus creating more power output?  I understand you are loosing some power with extra rectifiers, but I would think that keeping resistance down would be more important so that you keep heat down in your stator as well allowing you to run at higher rpm's.  I am new to this stuff and am still working on my first generator, so I really don't know but it sounds like that makes sense anyway.


And, yes, I would make the top part of the coils and the bottom part of the coils be the part that overlaps so that I could make the gap as small as possible.  But actually I am starting to think that this design still works better with one magnet rotor and a slotted laminate stator.  I think that is the direction I will be going with my generator anyway.

Devon

« Last Edit: July 05, 2004, 01:41:29 AM by (unknown) »

Ungrounded Lightning Rod

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Re: stacked coils idea, would it work?
« Reply #14 on: July 08, 2004, 05:17:10 PM »
1. "Three phases are about as many as you need to pull this off.  More phases just means more rectifiers and interconnection but no more power, since you can put the same amount of copper under the magnets with three."


Correct me if I am wrong, but part of what makes Windstuffnow's design work so well is the little amount of turns per coil.  In his last example he made ten turns per coil, and is contemplating wether or not he should have only have made eight turns if I remember correctly... I would venture to guess that by doing so decreases the amount of resistance.


That last sentence is where you go wrong.  Yes, fewer turns of thicker wire mean less resistance.  But they don't mean less copper losses.  What makes Windstuffnow's genny's good is that he used a high total cross-section of copper per coil.


Imagine a hundred-turn coil that produces one volt per turn and one amp through the coil.  It will have a certain amount of power lost to resistive heating.


Now split it in the middle, into two fifty-turn coils, and connect them in parallel to get two amps at 50 volts.  Same windings (though connected differently), same current in the wire, same losses, same power output (though at a different current/voltage tradeoff).


Now suppose the particular windings in the two 50-turn coils are side-by-side all the way.  No voltage between them.  So remove the insulation between them and weld them into a single figure-8 wire.  No change.  Reshape the wire from a figure-8 into a circle with the same cross-section.  Still no change.  Split the coils again and reconnect for 25 volts and four amps, 20 volts and five amps, or one volt and a hundred amps.  No change yet again.


You CAN reduce your copper losses by making the wire thicker and keeping the number of turns the same.  That reduces heating losses in the coil.  If your limit was how much you can heat the coil you can thus get more power.


But that also makes the coil fatter.  You can only go so far before something else has to change - like increasing the magnet spacing - to make room.  Increasing magnet spacing reduces power.  You can get it back by using stronger magnets or spinning them faster for more voltage.  But eventually you goof something up that moves your limit from heating the coils to something else you can't fix (like making your prop too inefficient.)


So let's not fool around with anything in his excelent design except the number of turns and wire thickness.  As long as we keep the wire cross-section times the number of turns constant we can play with the turn number to trade voltage for current and not affect power output, heating loss, or (unless we get down to a few turns of bussbar) how the coil fits into the space.  Even conduction of heat out of the coil remains unaffected (though finer wire may transfer a little more heat to the air if the ends of the coil are exposed).


And that lets us adjust the designed output voltage/current tradeoff of the generator to our liking, without affecting the total power delivered.


Is my explanation clear?

« Last Edit: July 08, 2004, 05:17:10 PM by (unknown) »

devoncloud

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Re: stacked coils idea, would it work?
« Reply #15 on: July 08, 2004, 06:17:17 PM »
Somewhat clear, but you are not talking to an electrical genius either :)


I understand the jist of it though and I think you are correct for the most part.  If you look at my last posting (Coil Resistance), Ed does a little more explaining, and states that he does use less wire with better results, and I would guess to venture it is solely because of his more efficient usage of space in the stator (many more legs under any one pole at any given time).


I think that the way he makes more coils but smaller also helps heat.  Yes, his system puts out as much heat as if he just used 12 bigger coils, but since they are broken up into many more smaller ones, I think this brings his overall temerature down some and lets him get away with pushing his generators harder.  In other words, 12 coils would run at 300 degrees, where 36 coils with the same amount of wire in the stator as the 12 coil example probably only gets to 180 degrees under the same load.  I am not sure about this, but I would bet a dollar or two that is right.  

Devon

« Last Edit: July 08, 2004, 06:17:17 PM by (unknown) »