Re: An Economical Magnecharger (inductive charger)

["Arthur Matteson" <awmatt@mediaone.net>]

> Also of note. The PFC20s use a inductor, and 40Khz of switching. This
> makes for a LOT smaller inductor transformer.

If I were doing this project, I'd make it a high switching frequency.  This allows sources besides utilities - such as solar
panels - to be connected up, without any efficiency loss.  The transformer will definitely be more efficient at a higher frequency,
at least according to many figures I've recently looked over.  I don't think the cost would be too much more with a switcher.  I
could design and possibly build a cheap one for you (if I have time).
An E core would be a good solution.  It would be easy to wind.

> Also you can get Powdered Iron Es.

I just realized that I was doing power supply testing with a powdered core instead of a ferrite core.  That might explain some
things.  : )

> Also I call Lams "Stacked Razor blades". I am not sure that I would
> want to handle them offten.

Yes.  I've been cut by these.  Nasty.
I don't think you would be able to build an I and E out of these, since they would have to be perfectly aligned when put together,
so they wouldn't short out.  From the transformer that I took apart, the E's and I's were staggered.  The entire reason for having
the laminated layers is to isolate them.  In a ferrite, this is taken care of, since the iron particles are separated by oxygen (I
think).

> In the PFC20s we are stuffing 5+ kw thru a 4 inch Torroidal core. It's
> even smaller than the Avcon receptical. With HF we could get this thing
> pretty darn small.

Oh, definitely.  With ferrites you can choose between a few types of cores - you could cut a toroid in half, to acheive lower EMI,
or you could just get two U or E cores and slide them together.  You just have to make sure dirt won't get in the way, otherwise it
becomes an air gap and the permeablity goes way up.  Maybe some design like the gasoline filler for a car?  You know, that flap that
covers the hole from inside...(I don't know its name)

> This of course is not a dumb cheap 60 Hz solution. Still the safeties
> and mode shifting abilities may be needed to pull off this concept even
> at 60 Hz.

That transformer sure would be heavy...even five pounds might be tricky to line up to the car for some people.

Good luck!

Art

P.S.:
> As a first cut, aim for a smallish onboard charger that can charge as
> fast as a standard 120vac 15amp 60hz outlet will allow. 120v x 15a =
> 1800w. Derating to 80% per NEC means 1440 watts.
I'm designing a 1800W plug-in charger at the moment.  Tomorrow I'm ordering my ferrite cores from Magnetics.  The applications
engineer said that he'd send me a few samples without even going through a formal process.  I bet you could get a free U-core to
experiment with; although you might need to be a student.... : D