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From: "Frithiof Andreas Jensen"
Subject: Sv: Seeking large high-permeability high-frequency ferrite cores
Date: Thu, 2 Jan 2003 23:10:41 +0100
X-Newsreader: Microsoft Outlook Express 5.00.2615.200
Organization: TDC Internet
Winfield Hill skrev i en
> I'm seeking a source for huge high-permeability high-frequency
> low-loss ferrite cores. Hopefully one of yo'all can help me!
probably not ;-/
The geometry of the coil is critical in minimising capacitive losses.
If you can work with one end of the inductor grounded, much can be gained by
using a disk winding because the high-voltage end can be moved well away
from the grounded core.
The important thing is to keep a good distance between the layers and that
the peak voltage is increasing as the layers move away from the core. If one
end cannot be grounded, you may use two disk-windings in series, with the
terminals on the outer layer and a good distance between them. In that way
only half the potential is close to the core.
You will probably want to use a ferrite rod instead of a "real" core - it
gives much more room.
If you have to use a normal E-core f.ex., some people will layout the
winding in a "xmas-tree" configuration:
But this is hard to do by machine; disks are much easier.
Finally, you could build a huge core out of "I" pieces, using several
windings in series and each gap being filled by an insulating sheet:
You may have to bond the "I" sections to some intermediate potential in
order to lower the capacitive losses.
Anyway, the key is to get lots of separation between the parts and still
maintain the magnetic coupling - and that is not so easy.
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