Power Transformer N87 Material, I assume your maximum frequency for LLC is below 100KHz...
There is always some high frequency current through these inductors which is the reason for heating up inductors found on al cheapo class d-amps. Most of the losses are due to core material, skin and proximity effects being less dominant.
The skin effect loss in the amplifier output filter Inductor at 20kHz is not significant compared to core loss.
At 20kHz, the skin depth in copper wire is about 0.46mm, at 5 times the radius this would be 4.6mm. The flat wire wound on the core has even lower skin loss than round wire.
This is interesting to consider, that even at 60Hz one needs to pay attention skin effect for some applications, like large mains power distribution: Microwaves101 | Skin Depth
"At 60 Hertz, no matter what the conductor, the skin depth is about 1 centimeter. That means that a power line 10 centimeters in diameter will satisfy the "five skin depths" rule (radius is 5 centimeters). Bigger than that and you are wasting copper. So to decrease losses on long high-tension runs, power companies sometimes hang double, and even triple wires for each power phase."
Skin Depth Calculator: Skin effect depth Calculator
At 20kHz, the skin depth in copper wire is about 0.46mm, at 5 times the radius this would be 4.6mm. The flat wire wound on the core has even lower skin loss than round wire.
This is interesting to consider, that even at 60Hz one needs to pay attention skin effect for some applications, like large mains power distribution: Microwaves101 | Skin Depth
"At 60 Hertz, no matter what the conductor, the skin depth is about 1 centimeter. That means that a power line 10 centimeters in diameter will satisfy the "five skin depths" rule (radius is 5 centimeters). Bigger than that and you are wasting copper. So to decrease losses on long high-tension runs, power companies sometimes hang double, and even triple wires for each power phase."
Skin Depth Calculator: Skin effect depth Calculator
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