I basicly agree with Tom... but I'll offer my current thoughts which may change tomorrow...
"I was sure that the double-magnet rotor system would produce more power(twice as many magnets =more power), however talking to him he believes that if you build a single magnet rotor with a steel slotted stator, you can produce a more powerful alternator. What are your thoughts on this?"
With slotted laminates you can have a much thinner airgap, so... for any given diameter and a given amount of magnets, I think you could have a lot more power. The dual rotor "system" requires a lot bigger airgap, and a lot more magnet.
" Is each ring a seperate piece of metal from the next ring of laminate? Is it necessary to insulate each ringfrom the other?"
It could be concentric rings, or... a big spiral, or lots of short segments. Each layer should be somewhat insulated from it's neighboring layer - but the voltage in eddy currents in very low, so the insulation doesn't need to be excellent.
"How thick do the laminates need to be?"
The thinner the better, but at some point it probably becomes a point of diminishing returns. I've got some old westinghouse generators that have laminates almost 1/8" thick in them...
"I am guessing that the laminate area needs to cover all the area the magnets do, that makes sense in order to catch as much flux as possible."
I would guess the same. I'd maybe consider slightly narrower than the magnets would be OK or good, but probably not wider.
"Next thing is air gap. I am assuming that the air gap is the reason behind the thought that the single magnet rotor with a slotted steel rotor is the way to go"
It's the way to go if you want the most bang for your buck in magnets... and it will allow for more power to be generated in a smaller space I think.
It may also have a different, possibly advantagous power curve - I'm not quite clear or sure how using laminates changes things there. It does, in my opinion, have the drawback of cogging, some iron losses, and - in an axial flux machine (which is what were mostly doing) the bearing will be under a constant load (there will always be a force attracting the magnet rotor to the stator). The advantage of a dual rotor alternator - although larger and perhaps more expensive in magnets and wire, is that there will be no loading on the bearing, no eddy current losses, and no drag due to hystoresis - so it will turn more freely and perhaps be slightly more efficient in low winds. Depending on your tools and resources, one may be easier to build than the other. To build a single rotor machine with slotted laminates, you'll have to buy good steel for the laminates and figure a good way to put slots in them. Like everything in this fun hobby - every choice has it's pros and cons.
