about coil sizes?

[jaskiainen]

Hi all!

The more i keep reading your postings the more confused i get.

Last thing what i found was that the coils shouldnt come much bigger than mags.

Is that so? And how bad it can be if my magnets are 1/2 inch disks and my

coils are lets say 1 1/2 inches height? And does it goes better if my coils

actually fit inside the magnet area?

I would have attached one picture here for clearance, but dont know how?

Just asked because my first attemp with renewable energy starts with quite small mags.

I dont even think i dare to say their diameters

[Flux]

Not sure where you found that but I must agree that you can find anything if you look far enough.

Assuming you are looking at a dual rotor axial of the simple type usually built here then I would suggest that you stick roughly to the following, but nothing is absolute.

Space magnets so that gaps between them are equal to or a little greater than magnet width ( dia if round). Make the hole in the coil magnet size or a little smaller. Make outside of coils so that at the closest point they just touch when assembled in the stator.

Make coil thickness about the thickness of one magnet. If you stick to this you will have something workable. It may not be the ultimate and things are a bit dependent on magnet shape but you will not go far wrong.

Flux

[jaskiainen]

Thanks Fux!

Ive already drawn a plans like that and was just checking that im not doing anything stupid.

[jaskiainen]

Oh here it is...

So the first one is better?

[Flux]

For round magnets I can't see any point in making the coils other than round or possibly elliptical. All you will do is add lots of resistance. I would never use trapezoidal coils for other than trapezoidal magnets.

Flux

[jaskiainen]

Thanks again

I just drawed the coils like this because it was easier for me to do )

The coils in my plans are round like this:


"80%" src="http://www.otherpower.com/images/scimages/9397/coil.jpg">


[motoman465]

Wouldn't it cause cancellation with both legs of the coil over the same pole as in the drawing?

Todd

[jaskiainen]

im not sure what you mean, but this was just question of the coil size against the magnet.

[martin1]

I think he means that the holes in the coils are too small.

http://www.fieldlines.com/story/2004/10/2/11043/6778

[jaskiainen]

yup

I did post another picture of the "real" coil but somehow it is cencored





This is the way im gonna do it

[finnsawyer]

The rule of thumb seems to be that the coil 'diameter' equals one magnet diameter plus twice the spacing between magnets.  For instance if the magnets are 1 inch in diameter with a spacing between them of 1/2 inch the coils will be about 2 inches in diameter.  let's see, does that work for a 12/9 design?  12x1.5 = 18.  18/9 = 2.

Eureka!  Well, you can refine it by drawing a picture, but it's close.  As far as height, if you make the coil too high (long) you will get a region of diminishing returns as the flux escapes sideways to the adjacent magnets.  A dual rotor design would help, but it's best not to deviate too much from established practice.  Set the diameter first and then the height or length.  If the length seems to be too long use smaller diameter wire and pay the cost of increased resistance.  I hope this helps.

[TomW]

jaskiainen;

You might want to reconsider using terms like "cencored". It is "censored", by the way.

Your comment was removed for gross violation of photo size guidelines.

Deletion due to failure to follow the rules is hardly a form of censure.

Just so you know.

T

[skipinder]

Hi flux, thanks for the precisions (is that a word, it is now...), what about the gap between the magnet and the coil, I guess I would imagine the closer the better?

[FredARose]

Ok, I have been working on a design with 1"x2"x1/2" thick Neos.  It is a dual rotor design and my question is should the coil be just a little bit larger than the magnet, or should it be shaped moe like the 9/12s of the rotor face area... Here area few pictures to make it clear.  It is a 9 coil, 12 magnet (x2), dual rotor design.

The three phases are indicated by the colors and the sq neos that are centered under one phase have a yellow dot.

I have been pulling out my Physics books on this one!  Which one is better..

Fred

[FredARose]

Here is a sketchup with all sq coils...