Re: Transformer coupling coefficients

On Tue, 29 Aug 2006 00:18:20 -0500, Don Foreman <dforeman@xxxxxxxxxxxxxxxxxxxx>
wrote:

I'd like to know what realistic or reasonable values for coupling
coefficients (k) might be in ferrite switchmode transformers. I'm
interested in forward converter power range of 50 to several hundred
watts.

I'd be interested in typical values for suitably-sized toroids, pot
cores, E-E cores and U-U cores. Bifilar and/or surrounded windings
(e.g. parallel windings above and below another winding) may be used.

Anybody have any experience with this?

Remembering that you did start this thread with a request for some typical
numbers, I found an old EC41 core set in the bin with some wire already on it,
and I took some measurements.

The first thing on the bobbin is a single layer, bifilar wound with a pretty
red and green pair of wires. The k between these two, calculated from
measurements at 1 KHz is .9991.

Then there is some Nomex, about 3 wraps, and another winding. The k between
one of the first layer windings, and the isolated winding on top of the Nomex is
..9962.
.

Relevant Pages

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  • Re: Transformer coupling coefficients
    ... interested in forward converter power range of 50 to several hundred ... cores, ... Bifilar and/or surrounded windings ... I often see the leakage inductance of a ferrite quoted as being equal to ...
    (sci.electronics.design)
  • Re: Transformer coupling coefficients
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    (sci.electronics.design)