Multiple Stator and Rotor System

[Walt]

Is it possible to stack two or more stator and rotor assemblies on the axial flux

alternator? If so can the back disk of the first unit also be loaded with magnets on the backside to be used as the front disk of the second alternator? Thanks, Walt

[Motorhead]

It's ok to stack the rotors and stators along the same shaft but do not place more than one set of magnets on each rotor plate for each generator stack...this has been tried before and doing this is will cancle out the magnetic field for the inside plates.

[Walt]

How much of an air gap should there be between the two rotor systems?

[hiker]

MOTORHEAD......

 are u the same motorhead in ALASKA ??

[windstuffnow]

  I built one up about a year or so ago, I didn't give it a thought about the magnets pulling the flux toward each other through the steel disc.  I calculated it would produce around 5kw and it only made half that when completed.  If you use separate discs for the magnets then it will come out ok.

  It has 2 discs with magnets on both sides and 4 stators.  Works but not real well...

Have Fun

Windstuff Ed

[Walt]

Just a thought. What about placing a disc of stainless between the back rotor of the first unit and the front rotor of the second unit. I'm thinking that it might break the flux between the two rotors.

[DanB]

It's intersting to me to see the replys about the fields cancelling each other on the same rotor.  Perhaps thicker steel might help with that.

But the 1st thing to consider in my opinion about this....

given the option (if diameter is not a problem) - you'll get much more power from the same magnets and wire... to stick with a single machine, rather than stacking multiple smaller machines.

Double the number of magnets on 1 disk (make it larger diameter), and you'd have twice the number of pole changes per revoltuion, so each coil makes twice as much power.  Double up the number of coils on one stator, (make it larger diameter) and you'll have twice the power.  So I think doubling the number of magnets, and coils in one alternator will yield 4 X the power, where using the same resources, and basicly building two alternators on one shaft would only yield twice the power. (I think thats right...)

so unless the diameter of the alternator is an issue, I don't see much point in having multiple rotors and stators, best to build it all into one.

[windstuffnow]

   I can get more power from a single rotor/stator unit than this one produced so basically it was simply just a fun project, disappointing but fun none the less.  Dan is right if your not pressed for space a larger diameter with more poles will do the job.  I've built up to a 3.5 Kw unit on an 8" disc platform but after 2.5 Kw they tend to get hot and need external cooling.  It really depends on the amount of power your looking for and the space required to achieve it.

    Spacing the discs even slightly will break the flux path between the magnetic discs and cure the problem.

Have Fun

Windstuff Ed

[Phssthpok]

Dredged from the archives...

Would there be a problem with mounting the center rotor magnets inside the rotor itself?

The finished product would be something like:

Standard design rotor

Standard design coil stator

'Double faced' rotor

Standard design coil stator

Standard design rotor

I was thinking in terms of cutting holes in the rotor that will accept the mags in a 'slip fit' (anchored with some sort of bonding cement) such that both faces of each magnet would be facing a coil stator. Is this viable, or is the steel backing of the rotor THAT integral to the magnetic fields acting on the stator?

[Don Cackleberrycreations]

Mythought would be to use a center disc and rather than mount the magnets directly to it . mount them in notches .

Basicly say your outer rotors contain magnets .5" thick your center disc would have magnets 1" thick that were mounted in notches so that the north and south poles faced the front and back rotor. Idealy for such a center rotor you'd have magnets made in an "H" or cut groves for mounting in the sides . this should avoid the flux canceling due to the steel disc , should it not?

The only real advantage I supose would be a single tower  rather than two seperate systems.

[irvin]

I am new to this board but I have built a single stack system with 24 mags and 9 coils for a VAWT System it works great. I am looking to try a 4 stack system. From what Ive gathered from other post the spacing between  rotors are key. I drew out a diagram of what I understand should work, the center rotors would have about 1" clearance between plates do you think this would still have a flux problem?

http://www.otherpower.com/images/scimages/9852/4_stack_stator_VAWT.bmp