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Flux cancellation

In this short movie the guy explains the technology behind his 1kW LLC converter:

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At 0:57 he replaces a monolithic 16:2x1 transformer with 4 4:2x1 transformers, which is a basic matrix transformer technology. OK.

At 1:50 he merges two U-shaped transformers into a single E core, still fine.

At 2:04 I got lost. He removes the center leg of the E core, basically returing to the U shape. But this is topologically equivalent to a toroid with 2x4 primary windings, in other words an 8:4x1 transformer. Since B=mu*H and H~N*I, he has flux doubling, not cancellation. He correctly concludes "half core size" (precisely, volume), but how did he get "half core losses"? Putting all the non-linearities aside, P_loss(B, 2*volume) ~= P_loss(2*B, volume).

Where am I wrong?

Best regards, Piotr

Reply to
Piotr Wyderski
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Piotr Wyderski

I'd think, and I have not watched the movie, logic: For example no core would be no core losses. Depends on the frequency, sufficiently high frequency coupling does not need a core.

If you have an air coupled transformer, then inserting a core would amount to RF heating it :-)

I am not going to watch that movie, am training how it is to live with low bandwidth internet now that I cancelled my cable subscription... LOL

Usenet will still work with my Newsreader, it was designed for that back in 1998.

hahaha

Reply to
<698839253X6D445TD

Right, core is core, doesn't really matter.

Tim

-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website:

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Reply to
Tim Williams

Thanks for confirmation, so another non-discovery.

Best regards, Piotr

Reply to
Piotr Wyderski

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