For reduction of proximity losses, an odd number of turns is required?

[treez]

Hi,
Would you agree with an SMPS transformer, you really need an odd number of layers of turns to reduce proximity losses?
eg PRI SEC PRI SEC PRI

...where PRI's are in pllel
and SEC's are in pllel.

(ie interleaving)

 

[wwfeldman]

since proximity losses are related to wires carrying the same current side by side,
interleaving primaries and secondaries may help
but the wires in a winding are next to each other, where litz wire helps reduce proximity losses.

 

[treez]

..thanks, and to get lower proximity loss with a pri and a sec...you ideally need an odd number of layers ?...so you get better interleaving?
(sorry, in the question title, i accidentally wrote "turns" when i meant "Layers".)

 

[wwfeldman]

no idea
i have done primary - secondary - primary on the theory (assumption?) that
it makes a small improvement in coupling.

i think one has to consider the trade offs between filling a winding layer, or not,
with whatever change in proximity effect one gets from layering.

this sory of ajdustment in the transformer design it will all depend on the window and the fill ratio for the transformer

i think the best thing is to use litz wire with lots of strands