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Forum Index : Windmills : What magnets??

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MacGyver

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Joined: 12/05/2009
Location: United States
Posts: 1329

Posted: 05:25pm 05 Nov 2010

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arewa

To pick up where Tinker left off, the reason using only one rotor disk gives very poor performance is there is no flux-return path. Flux is just like electricity; where there is no return path, there is not a complete "circuit" and things don't work well.

Using two magnet rotor wheels forces the flux lines to travel a finite, concentrated path; a path which subsequently completes the flux circuit.

Unfortunately, to the best of my current knowledge, the only thing you can do to a single rotor system to enhance its performance involves introducing iron. The iron will conduct the flux and that is why you see it in commercial uses as in an automobile alternator. I say unfortunately, because this causes drag and cogging.

The automobile alternator is actually a very poor performer on its own. Being tied to virtually unlimited horsepower (the car engine) it will keep a battery charged. Notice I said "keep". It does not do well recharging a 'dead' battery. By the way, most automobile alternators have to spin at around 10,000 rpm before they work as they were designed.

So, when you are designing and building a wind-driven alternator, you have to do it so there is little to no torque requirements at start up (i.e. no iron) and make it have the ability to charge your desired voltage at a reasonable rpm. Most wind systems have a "cut-in" speed of around 300 rpm plus or minus. Too slow, the thing stalls; too fast and you waste energy. It's a fine line, but it's the gold standard we're all working for.

It appears you are well on your way. Keep up the good work.

. . . . . MacEdited by MacGyver 2010-11-07

Nothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas

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