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I will make two stators
By devoncloud, Section Homebrewed Electricity Posted on Thu Oct 14, 2004 at 11:25:50 PM MST
laminates or not,....

Well, after thinking about this and also not knowing if my laminate idea will work (in terms of it pulling apart due to the forces of magnets or mounting problems) I have also decided to build a stator with no laminates. Besides no laminate in the second stator, it will be the same as the first stator in terms of wiring, coil size, amount of turns, and total coils.
Given the number of coils, there will be no open areas in the flux path as is the case with most double magnet rotor(three phase)generators. Most of those designs use large coils which end up being a bit on the fat side, thus making the gap between the two rotors very large and leaving a huge hole in the center of the coil where there is no magnet wire to capture the flux. This in my opinion is a waste of possible power output in the design.
doing the coils the same way I was planning on doing them with the slotted steel laminate, I have many thinner coils which will overlap on the top and the bottom legs of the coils. Since the overlapping occurs on the top and bottom of the coils (away from the magnet path), the side legs (the ones in the path of the magnets and thus the flux) can lay flat. This also utilizes all space in the stator by not leaving areas where there is no magnet wire to catch the flux of the magnets. Doing it this way makes the stator thickness minimal. Given the size of the coils, I think i can even put in the extra set of coils (as I originally planned in the slotted steel laminate design), and still have a thinner stator than most double magnet rotor designs with the standard three phase design.
I plan on building both stators, and then test the difference in output. I suspect that the non-laminate design will be far easier to build and have much less problems to overcome, but perhaps about twenty percent less efficient.
But, given the losses assosiated from cogging and eddy currents, perhaps the laminate-free design is the way to go.
Devon

I will make two stators | 9 comments (9 topical)

Re: I will make two stators (3.00 / 0) (#1)
by iFred on Fri Oct 15, 2004 at 04:46:50 AM MST

Hi Devon. I have played with both. I can say that I came to the ultimate conclusion that the dual rotor is the way to go. If you design your coils correctly and keep your coils thin, the increased magnetic field will generate more then enough power. The key is a very thin core!! (try for around 1/4 inch or so, the magnetic field is huge in their)

The only thing that has impressed me so far (in core design) is the output power of the induction motor conversion. Which is hard to compare with dual rotor designs. My dual rotor outperforms everything else that I have built with the exception of the induction motor, but that's another story. I bury my current meter without any problem beyond 10-15 and sometimes 20 or so amps, without that dual rotor even sweating.. seriously

It has been my experience over the last few years that the dual rotor IS the best you can hope for in making it yourself. It does not cog in low winds, it's fast on startup, it's a good generator of power overall when it does get going. It really depends highly on the blades/wind speed design and what they are doing. There is a lot of slack with the designs of the core and the magnet arrangements, all of which I have tried.

Just make your coils smaller (around 65 turns or less), and about 12 or more coils #14, 16 magnets per plate. I think you will be surprised at the output it produces in a good wind. I wish you well but always have fun at doing it!
>> all energy used to produce this comment or post came from solar and wind energy! It works!

Re: I will make two stators (3.00 / 0) (#5)
by zubbly on Fri Oct 15, 2004 at 06:20:35 PM MST

hello Devon / iFred !

iFred, you certainly did hit a note when you mentioned a thin stator. i did some experimenting using very thin air gaps and did show much improvement in performance.
it allows you to hit cut in voltage with less turns, thus allowing you to use fewer turns or make use of the bonus space with larger wire, increasing the current carrying capability of the stator.

Devon, i do keep an experimental unit for trying out different ideas and plan on using some flat wire. for example a #14 is available in a dimention that is .120 x .030 inches. that would give you a tight wound coil that is less than 1/8 of an inch thick and quite a stiff coil. careful thought and planning would have to be given in the location of the inner or start conductor ( pass it under the coil where it will be clear of the magnet path). you could also make a stacked (two coils on top of each other and joined in the middle with "then" both the start and finish of each coil on the outer perimeter ) LOTS of possibilities! :)

the wire i speak of is from www.alpha core.com ( i think that is the proper address)
check them out. available on ten pound spools.

hope some of the ideas will be of use to you!

zubbly

[ Parent ]

Re: I will make two stators (3.00 / 0) (#2)
by Michael G on Fri Oct 15, 2004 at 04:51:19 AM MST

Exactly what I have been thinking! Make use of both sides of the magnets! Making the rotor out of aluminum with pockets around the edges for magnet to slide into or pinch bolts to hold the magnets. Using to steel discs to mount the stators on and using the exact same coil scheme so there is no flux in wasted space! Keep us up to date on this one!

Re: I will make two stators (3.00 / 0) (#3)
by LEXX on Fri Oct 15, 2004 at 06:24:42 AM MST

If you are having a problem with the gaps in the middle of the coils try making a 6 phase stator. With 12 coils you would have 9 coils in each of two layers offset by This pretty much closes up any gap in the coils and like you said the overlap is outside the flux path. I personally think dual rotor is best, I haven't tried too many different designs like some of the guys here but the one I built is interchangeable with the different designs and the setup with dual rotors does very well. Please keep us posted with your progress.
LEXX

Re: I will make two stators (3.00 / 0) (#4)
by devoncloud on Fri Oct 15, 2004 at 07:20:35 AM MST

Well, everyone keep in mind that my original plan was to use Ed from windstuff now's slotted coil design AND his same coil configuration. This means sixteen coils per "single phase" (since there are sixteen magnets per rotor), and there are three single phases in his alternator design. This equals 48 coils at six turns per coil of number 14 wire.

Now, Where I was differing on my laminate core design from Ed, was that I am planning on putting another 48 coils on the back side of the laminate and make three more single phases out of the machine as well and add another magnet rotor. I am also planning to offset the coils from the back end from the front end in order to stop the cogging effect. The plan is to even rectify these phases seperately and everything, so this was in essense going to be two seperate alternators that simply share the laminate core and the blades.

I plan to do the exact same design - except without the laminate core... so, this means 96 coils of number 14 wire, six turns each coil. I know that this sounds like a lot, but on a 12 inch magnet rotor design, there is plenty of room to work with in the stator, and I can fit all legs that are in the path of the magnets on one layer with this design, I have already checked it out.

I am not sure just how thick the stator will be when I finish it, but it will be no thicker than 1/4 inch in the area of the magnetic flux path (the area where the magnet rotors will be spining). the area of overlap of the coils will be a little thicker(on the top and bottom legs of the coils), but I plan to route two small grooves for the top part of the coils and the bottom in the stator mold to make a bit more room for the overlay for the coils. The groove will take advantage of the space that is left behind due to the magnets no longer taking up that space. So in other words, the stator will be very thin in the 12 inch diameter, and just beyond the 12 inch diameter it will be a little fatter and also on the inner edge as well to allow for the overlay of the coils, but not widen my air gap. This is kind of hard to explain, but I hope you get the picture.
Devon

Re: I will make two stators (3.00 / 0) (#6)
by iFred on Fri Oct 15, 2004 at 09:32:38 PM MST

I know exactly what you want to do, I thought of the same thing about a year ago, still have not solved for some problems. The main problem you are going to have is supporting the core properly (which is going to be really difficult when you really think about it hard) and also in cogging. You can't get away from it. It does sound at first as a great idea, and it is, but I suggest that you first try to build a very small model to get a handle on it (also less expense). It is more complex then what you mention. Another problem is warping of the core at thinner core thickness'. Beyond this will be the fact that the core is going to be pushed and pulled during rotation and without adequate central and outside support it will rip it's self apart and destroy the core and coils. Another problem with core is heat, if your intention is to use fiberglass above and below for support, then your trapping the heat within. This will cause the core to warp and change. Metal causes heat when magnetic fields pass through it.

However, I wish you the best as always and keep us informed!
Good Luck!

>> all energy used to produce this comment or post came from solar and wind energy! It works!

Re: I will make two stators (3.00 / 0) (#7)
by devoncloud on Fri Oct 15, 2004 at 11:35:57 PM MST

yes, and thanks for the thoughts. I have figured a way I think will work to mount the stator, but none the less I am still going to build the stator without the laminates as well just in case the design does not work. I figure if it does, I will probably gain 20% power output, but then again, I do see several possible problems such as the ones you mentioned. Still, I think that the other design will work just fine if I cannot make the slotted laminate core work.
Thanks for the advise,and here goes nothing... I will keep you all posted on progress.

Devon

[ Parent ]

Re: I will make two stators (3.00 / 0) (#8)
by hvirtane on Sat Oct 16, 2004 at 11:03:54 AM MST

I think that cogging with
this design will be quite little.

It will be interesting to see
how the coils from the different
sides will influence each others.

Please keep us posted.

Hannu

Re: I will make two stators (3.00 / 0) (#9)
by scoraigwind on Sun Oct 17, 2004 at 04:21:38 AM MST

It is true that a thin stator will get higher flux density, but more % of the total gap space has to be wasted in the clearances between rotors and stator. You get more flux but you have less room for wire and the tradeoff has to work for you. As the stator gets thinner and thinner, you don't actually get that much more flux because you still have to maintain a decent clearance if you want long term reliability. And a thin stator is more fragile and liable to warp and crack.

Overlapping the coils at the inside and outside is an option to increase the copper in the gap but it will mean a lot of extra length of wire (resistance) and a lot of hassle to build it. And it will be a tight fit on the inside ends of the coil. The 3-phase design I use with 'fat' coils does waste some space at the centre of each coil but overall it uses about 60% of the available space very efficiently, and the turns are kept very short and simple.

You could do a 3-phase design with overlapping coils (don't forget to reverse every other coil connections, or this could better be described as 6-phase). This will fill more space with copper but mean that you need a tortuous path for the end windings at the centre to get past each other. It will be difficult to measure the clearances (magnet face to coil face) because of the mushroom shape of the stator edge, but make sure you have adequate clearance to work long term in the real world.
Hugh Piggott http://www.scoraigwind.co.uk

I will make two stators | 9 comments (9 topical)

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which stator will work better?
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