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An Alternate PM Alternator Design | 50 comments (50 topical)
Re: An Alternate PM Alternator Design (3.00 / 0) (#19)
by finnsawyer on Tue Apr 25, 2006 at 09:03:18 AM MST

No offense taken.  I like the give and take.  It tends to expand the mind.  A while back we were speculating here about trading magnets for copper.  Well, this may do that.  Not necessarily a bad thing.  But still, it has to produce enough power at a reasonable cost.  The jury will be out on that for a while.  

When you speak of dead wire I presume you are referring to the wire along the top and bottom of each coil.  I guess I missed that in your comment, although I was aware of the issue.  That wire is there to complete the loop.  Every design has to put up with it.  To minimize its effect you have the magnet be as large as the inside of the coil.  Also make the magnets and coils round.  The alternator should still work in that case, but don't expect nice rectangular pulses.
GeoM
[ Parent ]



Re: An Alternate PM Alternator Design (3.00 / 0) (#23)
by kitno455 on Tue Apr 25, 2006 at 05:26:51 PM MST

as i understand it, having the magnet as large as the inside of the coil will not minimize the effect. the parts being passed over by the magnet are the only parts that generate voltage. in your design, thats the short sides of the coil, while the long sides just contribute resistance.

just my guess, but it looks like you can get the more power from the same mags and less wire, by going with smaller coils.

allan

[ Parent ]



Re: An Alternate PM Alternator Design (3.00 / 0) (#25)
by finnsawyer on Wed Apr 26, 2006 at 10:09:55 AM MST

There are two things that make or break an alternator design.  Firstly, you need to get the proper voltage at the cut-in speed.  This depends on the number of turns (note turns, you can't make an alternator with only radial wires) and the strength of the magnetic flux.  Larger flux, fewer turns.  That applies to this design as well.  Once you have established the number of turns the second requirement is current carrying ability or resistance.  The solution to lower the resistance is to use heavier wire for the same number of turns.  You now made the coil bigger.  This requires a larger rotor.  That will give a lower cut-in rpm.  That is true for this design as well.  So, for a proper combination of magnet size, wire size, number of turns, and rotor size it should be possible to satisfy the design criteria.  The problem of course is that these things are all interrelated.  It will take while to sort them out.  The design currently used was obtained by trial and error.  I suspect the same will hold true for this one.
GeoM
[ Parent ]


An Alternate PM Alternator Design | 50 comments (50 topical)

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