I am betting there are flux guides involved however it is done. Some iron in the circuit does wonders for concentrating fields, though high frequencies...is permeability of material a function of frequency? I always did DC magnetics.
The cores in transformers are no more or less than flux guides that are magnetically soft to reduce loses to heat. Maybe a simple isolation transformer (1:1) works if you can put the sending and receiving coils on U shaped cores and the mating faces are brought close together, preferably touching. The core/pole faces are not electric contacts, so no arcing, they carry the current in the flux gradients. Still any eddies that are generated in the flux guides are a loss - the kind of power we are talking about might even need cooling. I actually like big-assed contacts for this, not inductive. But I am simple minded. I think I would rather plug it in than build all this for induction. On Wed, Jul 23, 2014 at 12:47 PM, Lee Hart via EV <ev@lists.evdl.org> wrote: > From: George Tyler > >I have done a lot of transformer and inductor design over the years, > always > >said "you can't focus or direct a magnetic field", apart from ordinary > >magnetic materials of course. On day I found something that someone had > put > >together on the web: He pointed out that if you have a resonant coil in a > >magnetic field then the field it creates cancels the field around the > >outside, and enhances it in the center on the coil. The effect is just > like > >"sucking" in the field into the coil! > > That's true. You get the same effect just by having a long solenoid coil, > where every turn has the same current in it. The magnetic flux travels all > the way to the end, and then loops back around to the far end. Or a similar > effect can be observed in a toroid, which can be looked at as a long > solenoid coil, bent into a donut-shaped loop. > > However, that's not very helpful when you have a primary and a secondary, > unless you can put one winding on top of the other (so all the flux lines > link both coils). > > The resonance effect can make the flux lines link, because again you can > make the current and phase in both coils identical. But then you can't > extract any power from the second coil. :-) > > One other technique is to surround the transformer with a very good > conductor; like wrapping it in thick copper sheet. The copper shorts out > the magnetic flux, forcing it to stay away and flow along the other path > you would prefer. You'll see this done on transformers in high quality > audio gear, to "shield" or block the magnetic field from escaping to cause > hum in the audio. Vicor uses this same trick to squeeze a little more > efficiency in their switch mode transformers. > > > -- > Excellence does not require perfection. -- Henry James > -- > Lee A. Hart http://www.sunrise-ev.com/controllers.htm now includes the GE > EV-1 > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA ( > http://groups.yahoo.com/group/NEDRA) > > -- Put this question to yourself: should I use everyone else to attain happiness, or should I help others gain happiness? *Dalai Lama * Tell me what it is you plan to do With your one wild and precious life? Mary Oliver, "The summer day." To invent, you need a good imagination and a pile of junk. Thomas A. Edison <http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> A public-opinion poll is no substitute for thought. *Warren Buffet* Michael E. Ross (919) 550-2430 Land (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google Phone (919) 631-1451 Cell (919) 513-0418 Desk michael.e.r...@gmail.com <michael.e.r...@gmail.com> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140723/75617dda/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
