inductive charger core geometry

It might help somewhat. But I've torn a few apart and they just use a cylindrical core with a winding on either side of the gap.

It helps that they run at about 100 kHz.

Simple circuit

Shows air core coils 1-1/2" and 13/16"

Most that I came across ran around 60-80kHz. And yeah, usually just a big old chunk of ferrite with wire around it. Got to keep them profit margins up there ...

Really good contactless chargers operate the drive side in series resonant fashion.

Ok, on the Iron. I'll play around with that some - I was thinking a pair of planar core halfs. As far as the series resonant design goes, I've just about abandoned that idea. My SR simulations aren't cooperating with me. I think I may end up with too much variation in the gap which will detune the circuit. Have you any insight on the really good ones. A manufacturer name or any patent info would help as Ilike the series resonant approach. I'm looking at 500kHz to 1MHZ to run this thing. I'm thinking of a half bridge which will commutate very nicely with a lagging current.

regards, Bob

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I've made one of these things in the past. You need to spread out the resonance peak with a bit of resistance in the coil ie detune it somewhat. Having that resonance makes a big difference in the size of the charging gap. Typically I was getting good charge transfer at about 2x coil diameter.

MHZ

org/- A UK political party

Ok, thanks Dirk. I'll take another look at it sometime in 1Q 09 and report back to the group.

Merry Christmas

Regards, Yzordderrex

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