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