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making a new wind generator.
By devoncloud, Section Homebrewed Electricity Posted on Fri Oct 08, 2004 at 06:48:57 PM MST
Well, here I go again!

I am making another wind Generator. I have just recieved sixteen wedge shaped neos and some silicone steel for my laminate.
It will be a slotted stator design such as the design that Ed from windstuff now has done. There will be three single phases of coils (sixteen coils in each single phase)equalling 48 total coils. The coils will be six turns a piece, the biggest wire that will fit in the slots (Ed thinks no 14 will be the one, I guess time will tell).
The magnet rotor will be a 12 inch disk, the blades 8foot diameter at tsr of 8 I think, not sure on the tsr as of yet either.... about the only thing I am sure of so far is that it will be of the slotted stator design, 12 inch magnet disk, sixteen magnets, three single phases, 48 coils total. This is the basic design, and I will get started building this part of the project this weekend.
OK, so I have gotten a little power crazy here and have begun to think of more possible output, and have decided that I may want to also slot the back side of my laminates, so that I can fit coils on the back of the laminates and the front.... and then add another 12 inch disk and another sixteen magnets. I would line the magnets up where the poles of the magnets facing each other are the same and perfectly alligned with one another.
As far as the slots on the steel laminate, I will offset them from the front side. The reason for this is so when the front side is in the position where the cogging is the worst, the back side is not experiencing the cogging affect at all and vise versa.... The thought is that perhaps the cogging effect will in essense "cancel" itself out... but, even if this is not the case, at least the cogging effect is not doubled due to both sides cogging at the exact same time.
I will also keep the sides totally seperate from one another until after they are rectified. In other words, it will be two seperate alternators, only sharing the laminate and the force of the props.
I am thinking that I will use steel disks for the magnet rotors rather than car brake rotors in order to cut down on some weight in the design....
Oh, and of course the furling tail.
I figure if I could pull this off, no way I won't be making enough juice for that stupid fridge.... at least that is the hope anyway. I will still have to buy some more battery power too.
Hope I explained this good enough to envision..... what do you all think?
devon

making a new wind generator. | 20 comments (20 topical)

Re: making a new wind generator. (3.00 / 0) (#1)
by Electric Ed on Sat Oct 09, 2004 at 05:12:40 AM MST

Sounds fine except this statement-

[quote]"I would line the magnets up where the poles of the magnets facing each other are the same and perfectly alligned with one another."

I believe that in a dual rotor machine the opposing magnets should be of opposite polarity.

Re: making a new wind generator. (3.00 / 0) (#3)
by devoncloud on Sat Oct 09, 2004 at 11:28:10 AM MST

Thanks EE...

I am wondering though, since this is not a true dual rotor machine (in the sense that the rotors are not "charging" the same sets of coils) if the old rule holds true. I am in essense making two alternators here, only sharing my steel core laminate. there are 48 coils on the front side being charged by the front magnet rotor, while there are 48 coils on the back side of the laminate being charged by the back magnet rotor. The two sides will even be rectified seperately.

But you bring up a good point, which is what setup would better serve the design? Since it is two different alternators I think both would produce power, but which one would be better (if any)? Would the same poles hitting the same area of the front and back of the stator be better or would it have a bit of a canceling affect or vise versa? This should be a interesting test. Anyone out there ever played with this before?
Devon

[ Parent ]

Re: making a new wind generator. (3.00 / 0) (#5)
by Flux on Sat Oct 09, 2004 at 11:44:55 AM MST

My instinct makes me suspect that if your core material is sufficiently thick it doesn't matter what you do to the two sections.

If it is not thick enough to be absolutely sure of this, I would put the slots on one side where the teeth are on the other so that you do not cause very thin areas.

Reduce cogging by altering one rotor disc in relation to the other to get the best result.

There would probably be little difference which way you put the magnets but I would be tempted to put them with the same polarity facing so that the flux goes the same way on both sides.

I think that if you get this to perform to its full potential it will be too powerful for an 8ft prop especially with tsr 8.

Flux

[ Parent ]

Re: making a new wind generator. (3.00 / 0) (#14)
by finnsawyer on Sun Oct 10, 2004 at 09:33:58 AM MST

If you put two equal N poles facing each other the magnetic flux midway between them will be zero. This is accomplished by the flux going out to the side. Flux going to the side does not contribute to an induced voltage in the coils. E E is right. In order to maximize the flux crossing the coils you need to have opposite poles on the two sides. For what it's worth, as I mentioned in a previous comment, you could have all north poles on one side and and all south poles on the other with appropriate spacing between magnets. You still need to provide a way for the flux to loop and need to keep the air gaps small. It's possible that the south poles might not need to be aligned with the north poles, but could be centered over the spaces between the north poles. This might reduce output but might also reduce cogging. It really boils down to building it to see how it would work.
GeoM
[ Parent ]

Re: making a new wind generator. (3.00 / 0) (#2)
by hvirtane on Sat Oct 09, 2004 at 11:15:01 AM MST

As far as the slots on
the steel laminate, I will
offset them from the front side.
The reason for this is so
when the front side is in
the position where the cogging
is the worst, the back side
is not experiencing the cogging
affect at all and vise versa....
The thought is that perhaps
the cogging effect will
in essense "cancel" itself out...
but, even if this is not the case,
at least the cogging effect
is not doubled due to both
sides cogging at the exact same time.

I think that this is a good idea.

I'm sharing the idea of 'Electric Ed'.
I would put the magnets opposite
poles facing each others.

You might try making also another
stator without laminates to test,
which is the better method?

- Hannu

Re: making a new wind generator. (3.00 / 0) (#4)
by devoncloud on Sat Oct 09, 2004 at 11:39:30 AM MST

Good point Hannu. Since this is a test on a new design, making a second stator without laminates may be a good idea just to see which would produce more power. I have made a dual rotor alternator, but it was the original Hugh's five phase design, 12 magnets a rotor sandwiching ten coils. I was not impressed with the output, then again it was the first generator I ever made, so I am sure the output problems had alot more to do with me than the design.
Devon

[ Parent ]

Re: making a new wind generator. (3.00 / 0) (#6)
by stop4stuff on Sat Oct 09, 2004 at 12:37:42 PM MST

Hi Devon,

check out this discussion, started by Troy...
1 magnet, 1 coil, 1 AC wave

Originally I thought that AC wave generated by a coil as the magnetic flux passes it was due to the flux passing thru the center of the coil... not the case, as can be seen by Troy's posting.

Currently, I am working on an alternator that has no iron/steel material in the rotor, there are 12 1"x1/4"x1/4" magnets mounted 'spoke like' in 4" acrylic sheet disc. The magnets oppose each other radially, so that there is a concentration of magnetic flux being forced out of the sides of the rotor to produce electricity from 20 coils (1/3" or ~8mm depth)... 10 either side of the rotor set up for 5 phases with 4 coils per phase.

I am still testing and improving the setup... so far, with a stationary steel backing to the coils, the output is increased by around 20% (vs no backing to the coils.) There is some serious drag to gain this improvement... my next testing stage is to use steel that has magnetic memory to make 2 rotors (1 each for the outside of the coils) so that the alternator is a sandwich;
rotor plate, stator CW wound coils, rotor magnet/acrylic plate, stator CCW wound coils, rotor plate

I'm using 28 SWG wire for the coils (there's a difference between AWG and SWG in wire numbering) and I'm confident at a final output of at least 10w at 300rpm.

For me opposing magnets is working.

Once the alt is optimised I shall be posting results.

all the best,

paul

Re: making a new wind generator. (3.00 / 0) (#8)
by LEXX on Sat Oct 09, 2004 at 05:40:02 PM MST

Is your stationary steel backing a plate, if so, shouldn't that produce quite a bit of very unwanted heat?
LEXX

[ Parent ]

Re: making a new wind generator. (3.00 / 0) (#11)
by stop4stuff on Sun Oct 10, 2004 at 04:15:51 AM MST

I didn't check for heat, but i understand what you're saying.
As it is I won't be using stationary plates, but ones that rotate with the magnet rotor.

paul

[ Parent ]

Re: making a new wind generator. (3.00 / 0) (#19)
by troy on Mon Oct 11, 2004 at 12:26:30 PM MST

Don't forget that an air core coil may behave somewhat differently than an iron core coil. One coil will still make an AC wave in one pass of the magnet, but the iron core makes it more efficient with better peak voltage values. But it also increases cogging and adds manufacturing complexities.

So you takes your choices...

Best regards,

troy

[ Parent ]

Re: making a new wind generator. (3.00 / 0) (#7)
by Gary D on Sat Oct 09, 2004 at 03:56:18 PM MST

Devon, I think you may have problems with your laminates being yanked back and forth. On the old board, several people had problems with the larger magnets ripping out the laminates. This was with only one side having magnets however; don't recall anyone trying exactly what you will be attempting. Perhaps I'm confused, maybe Dan or someone else that used the large neo's will chime in. If you have n-s across from each other, my thinking is that you'll have twice the pull-push as a single magnet? One of the many practical reasons they changed to air core I think. Hope I'm wrong, have a pleasant weekend. Gary D.

Re: making a new wind generator. (3.00 / 0) (#9)
by devoncloud on Sat Oct 09, 2004 at 07:46:06 PM MST

thanks Gary D. I have been wondering about this myself, and, (kind of a related problem) how to mount the stator in the first place. I have decided that four pieces of angle iron placed at the top, bottom and both sides of the stator (and then welding the other sides of the angle iron pieces onto the frame of course) will do the trick hopefully. The way I have thought about mounting the stator to the four pieces of angle iron will be to drill holes through the width of the laminate, and putting a skrew or a shaft of some kind (something that is non-magnetic so to minimize eddy currents if that will work) through the stator and mounted with bolts or pins or something like so (forgive the horrible image):

Think this would work?
Devon

[ Parent ]

Re: making a new wind generator. (3.00 / 0) (#10)
by devoncloud on Sat Oct 09, 2004 at 09:21:11 PM MST

looking at the picture after I posted it, the text did not show up too good. The red line points to the laminate, the green lines points to the non-magnetic skrews or shafts that are going through the laminate to hold it in place, and the blue lines point to the angle iron that will be welded onto the frame in order to hold the stator in place. Hope this helps to clarify a bit, I know the picture is not the best in the world :>)
Devon

[ Parent ]

Re: making a new wind generator. (3.00 / 0) (#12)
by Gary D on Sun Oct 10, 2004 at 06:53:00 AM MST

Devon, if the laminates are wide enough I "think" your plan will work! Others are welding the backs of their laminates (not sure how deep the saturation point is). If you got 3/4 or wider laminations could be that it won't be a problem. But then you possibly could have 2norths facing in and next 2south facing in to push at the sametime going around the circle So the push/ pull balance out( if the magnetic forces don't reach in too far?). Otherwise, the pull no matter how thick "could" yank the laminates. This is how my current thoughts are: always subject to change! Good luck, if you use a 5 stud arrangement, and issues arise, you could just move over 1 stud on 1 rotor to give a different magnet viewing. As I said hopefully someone with the lamination issues earlier will give their thoughts! Glad you understood and were looking for input. Looking forward to any results! Good experiment, worth a try! Gary D.

[ Parent ]

Re: making a new wind generator. (3.00 / 0) (#15)
by devoncloud on Sun Oct 10, 2004 at 10:57:09 AM MST

Thanks Gary, and I do have 3/4 inch laminate. It is siliconed steel. I am a bit worried about perhaps pulling the stator apart, but, am hoping that the magnet rotors will be pulling and pushing at the same time, therefore sort of canceling out any forceful pull in any one direction, and if it does, then I will take your advise and move one rotor over a stud. I am also thinking that the four skrews or shafts that I put through the turns of laminate will hold it in place strong enough as to not pull the turns of laminate away from each other as well. The laminate is one solid piece simply rolled up, so in order to tear the stator apart it would have to pull the turns away from each other (sort of like a slinky or something) which would mean it would have to break the skrews or shafts to do it since the the skrews will be going through all the turns holding them in place. I guess we will see for sure if I indeed get it up and running.

I think you all are right in making my prop last. This is also the part of making wind generators I am the worst at also,so saving it for last sounds good to me anyway ;>).... Figuring tsr and the size of the blades and whatnot is confusing to me, but I guess I will have to figure it out here soon enough. I need to read up a bunch more on how to figure out tsr (and size of prop)in relation to the output of the alternator I guess, it is a lot of info for my brain to try to calculate... I guess I should have studdied the books in college instead of female anatomy and fermenting processes of Beer!!!!!!!

devon

[ Parent ]

Re: making a new wind generator. (3.00 / 0) (#13)
by DanB on Sun Oct 10, 2004 at 07:48:32 AM MST

Interesting idea and it'll be a fun experiment.
I wouldn't plan too much about the prop untill you get some sort of power curve from the alternator - I agree with other statements which suggest that if you build it well, it'll likely be too powerful for an 8' prop.

I also think you'd get quite a bit more power (twice the power) from it if you went with one rotor, and a larger diameter - and put all your magnets on that rotor, but it would probably cog a bit more - your plan for two rotors would definitely improve the cogging situation. But - a more powerful alternator would allow for a larger prop which might help overcome the cogging to a large degree.

Re: making a new wind generator. (3.00 / 0) (#16)
by devoncloud on Sun Oct 10, 2004 at 11:21:43 AM MST

Thanks Dan, I agree about the prop, and this area is the one I have the most difficulty figuring out as well, so I will be listening to you all in this area given you all have much more experience in this area than I do. I need to read up a good bit more on prop size and tsr to fully understand it in relation to the alternator. so far I have done what others have said, but have not really figured out these calculations for myself, so I am a bit relunctant to say the least about comming up with a final size and tsr. I guess building the stator first and figuring out what it can do will help me to figure out the calculations on the props, at least I hope anyway.
devon

[ Parent ]

Re: making a new wind generator. (3.00 / 0) (#17)
by scoraigwind on Sun Oct 10, 2004 at 04:24:33 PM MST

There will be some flux in the part of the laminations that goes from coil to coil along the back (middle of core with two sides). If this piece is thin then it is a good idea to put north opposite to south so that much ar all of the flux goes straight through.

Whatever there is nothing to be gained by putting north opposite to north.

To minimise cogging I think it is very important you put the slots on one side opposite to the teeth in the other side. This will make a big difference. so the magnets also need to be a little different in positions to match this skewing.

Having two rotors will help by reducing the thrust load on the bearing (balancing it out). But you will still get iron loss and cogging.

How do you plan to cut the slots?
Hugh Piggott http://www.scoraigwind.co.uk

Re: making a new wind generator. (3.00 / 0) (#18)
by devoncloud on Sun Oct 10, 2004 at 08:39:27 PM MST

Hello Hugh,

I guess that I will have the slots machined at a shop. I have thought of taking my angle grinder and making some sort of sliding base to mount it on and do it myself, however given the fact that I have basically no metal working skills whatsoever I may be better off letting a professional take care of this.

I have decided that the opposing poles is a better choice, thank you all for pointing out the pros and cons of the idea. There will be more pull on the laminations that way, however I think my idea on how to mount the stator will stop the forces of the magnets from pulling the laminate turns apart.

One thing I am worried about however is the screws that I will be inserting into the stator to hold it in place. I am worried about eddy currents. I know that steel screws is not a good choice because of eddy currents, so what is? Should I use brass or titanium or something? Oh well, that might be for another post, unless someone out there reading this knows the answer.
Devon

[ Parent ]

Re: making a new wind generator. (3.00 / 0) (#20)
by Electric Ed on Mon Oct 11, 2004 at 12:28:26 PM MST

[quote]"I am worried about however is the screws that I will be inserting into the stator to hold it in place. I am worried about eddy currents"

Using brass screws will prevent hysteresis losses but will do nothing to prevent eddy currents, which would occur in any conductive material.

A larger number of smaller screws should reduce the losses to a negligible value.

EE

[ Parent ]

making a new wind generator. | 20 comments (20 topical)

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