Ok, so some sources suggest that for an LLC supply you can use solid wire for xformer vindings IF the resonant inductor is implemented as a seperate inductor.
It looks very, very wrong, but it would be so much simpler and I had to test it. I tested with solid core for both primary and secondary, and efficiency stayed above 80% for 150w out Including rectifier and all.
I switched the primary to 8 strands of thinner wire and kept the solid secondary. Efficiency peaks around 90% for 150w out.
This is a etd39 core and lowest frequency for max load is 80khz.
Secondary is 1.3mm solid wire!
I will test again with 8 thinner strands for secondary, but I don't expect much improvement.
Unless I botched the measurements this is somewhat surprising to me.
It looks very, very wrong, but it would be so much simpler and I had to test it. I tested with solid core for both primary and secondary, and efficiency stayed above 80% for 150w out Including rectifier and all.
I switched the primary to 8 strands of thinner wire and kept the solid secondary. Efficiency peaks around 90% for 150w out.
This is a etd39 core and lowest frequency for max load is 80khz.
Secondary is 1.3mm solid wire!
I will test again with 8 thinner strands for secondary, but I don't expect much improvement.
Unless I botched the measurements this is somewhat surprising to me.
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I assume that the reduction of stray field between tight coupled windings reduces eddy current loss.