Additional losses in high frequency magnetics due to non ideal field distributions

Finite-element modeling is used to visualize and quantify four loss mechanisms: leakage fields due to air gaps; orthogonal fields due to the gap between the winding and the window; interactions of windings with half-wave currents; and shield eddy currents. This finite-element modeling effort demonstrates that there are additional losses in high-frequency windings beyond those included in the conventional analysis based on P.L. Dowell's work (1966). These losses may be significant, depending on the particular circumstances. In general it is necessary to model the geometry of interest to determine the additional losses. Two useful rules of thumb appear: space windings at least a distance of twice the air gap length away from the gap and make shield foils thin compared to the skin depth.<<ETX>>