How is Litz wire handled?
The actual stranding configuration of the Litz wire is not accounted for. It is assumed that you will be using a Litz wire configuration such that the AC resistance effects at the operating frequency are minimized. It turns out that when this is done, adding 10% to the DC resistance comes very close to solving the problem for all of the stranding variations (twisting of the internal wire). For non-toroidal designs, the field-based estimate assumes a Litz strand equal to tLitz diameter. TLitz defaults to .0025 inches or #42 wire. The field simulation will give accurate results for the tLitz size. If tLitz < sd (skin depth) the approximation that Rac = Rdc is pretty good. You can change tLitz in the calculator or by making your own tLitz button.
