Double stator

[zvizdic]

I am tempted to try building alternator with 2 stators and 1 double sided rotor 12 1/2x1x2 per side.I heard and read about many burned stators .Heat is a big issue with stator being sandwiched between 2 rotors.Stator on the outside offer many possibilities like steel core, heat sink on outside and fully enclosed design.In sandwich design strong magnetic field is a big advantage witch will bi lost.Any  idea or suggestion on a design or power output ?  

[ChrisOlson]

Every stator I've lost was because something else went wrong.  I guess when you build a stator it should have a max continuous output determined for it, and a max intermittent output determined.  If you exceed either one of those it will burn up.  It doesn't make any difference if it's between two magnet rotors, or hanging out in the open with a rotor only on one side of it.

As far as design, a stator with more coils and less turns runs cooler than one with fewer coils and lots of wire in the coils.  And you're right on the loss in efficiency - I don't think a single rotor axial flux using two iron core stators will make as much power as a dual rotor with one stator, using the same magnets.  So just by the act of reducing the generator's potential output by not using the magnetic flux to its full power, you already made it run cooler.  But I don't think that's what you were trying to achieve.

--

Chris

[wpowokal]

Er I struggled to understand your concept but am convinced you have not grasped the full concept of air core alternators. Take note of the other response, buy a book, don't try re-inventing the wheel, there so much scope for burning stators by straying from the basic design or not understanding it.

Then again maybe I completely missed the point of your post.

Allan

[fabricator]

The way I understand it these machines use the dual steel rotors so the magnetic flux is both trapped between the rotors and has a pathway from the north side of one magnet and the south side of the magnet on the other side, making for the maximum flux lines and therefore the maximum number of cuts on the copper windings.

[ADMIN]

You'll get much better 'bang' for your buck by ditching the dual stator idea and simply build a larger diameter alternator with more magnetic material and more copper wire.

Basically, if you double the diameter of an alternator, and use twice the

magnets, and twice the copper - you will get 4x the power at any given

speed (because each coil is producing twice as much power when twice as

many magnets go by per revolution and you have twice as many coils).

If you double it up as your suggesting (2 stators  - twice the magnets

and 3 steel rotors -the middle one having magnets on both sides) then

you're using the same resources as you would had you just doubled the

diameter - but you only get twice the power at any given rpm.

ADMIN

[Flux]

It's worse than that in this case, by changing from a dual rotor to 2 single rotors the flux is reduced by something like 50% and normally the power out varies as the square of the flux. With a lower flux density and twice as much copper the power will be way down. Certainly a good way to prevent it burning out  but as Chris said earlier not for the intended reasons.

Flux

[bzrqmy]

ZVIZDIC,

You make me smile.  After researching this subject for a couple hours,  I was thinking the same thing.  This subject somes up at least once a week on the forum.  

Sometimes there will be harsh responses about how this is a bad idea.  It's just because we see it so often.  

Here is my theory.  I  belive that it takes a special kind of person to even visit this forum.  Obviously you have some kind of interest in this subject.  Good for you.  I think it is in our nature to try to improve on existing designs.    I think Dan says it best about the resources required to build a double stator machine.  So, after researching for a long time and buying the Windpower book sold on this site, I have built a 10 foot machine which is a proven design.  I am still struggling to control this thing.  My suggestion if you are considering a project like this is to read as much as you can in the archives of this site, buy the book and ask questions.  

Cheers,

Pat