Study of geometrical effects on high frequency winding loss of air-gapped power inductor design with DC current impact.

This paper summarizes geometrical effects on power inductor winding losses based on 4 different winding configurations (concentrically cylindrical, disc-typed, constant, and variable wire diameter methods). Relevant DC winding resistance for 4 winding configurations are derived. An effective inductor design method is given by considering the ratio of k (k=I_av/∆I) , the ratio of skin depth to wire diameter 2r/δ for fixed and variable wire diameter cases as well as a ratio of skin depth to the winding thickness (t/δ ) for concentrically cylindrical and disc-typed winding cases. The core gap effect on the AC winding loss can be optimized by smart selection of the ratio of h/lg.