Improved winding loss theoratical calculation of magnetic component with air-gap

For inductors, such as DC chokes, PFC inductors, resonant inductors and fly-back transformers, magnetic field distributions in winding windows are extremely complex due to the air-gap fringing effects in the core. Existing high-frequency winding loss calculation method usually ignores the fringing effect losses caused by air-gap fringing fluxes, resulting much errors for winding loss analysis and loss reduction designs. In this paper, an improved winding loss theoretical calculation method of gapped inductor is proposed. By replacing the air-gap magnetic voltage drop with equivalent surface current sheet with certain shape and certain current density distribution near the air-gap, the winding loss accuracies were improved. And then mirror-image method was used to equivalent the influence of the boundaries of high permeability magnetic core. The mirror image method was extended to dual 2D model approximation of 3D model.