Winding loss analysis and optimization of an AC inductor for a galvanically isolated PV inverter

This paper describes simple treatments for fringing fields of air gaps in the core and bypass fluxes in the winding window area of an existing high frequency AC inductor used by a commercial developer of PV inverters. For this purpose, Maxwell (ANSOFT) electromagnetic software package is used for winding eddy current loss analysis. It is displayed that air gaps cause high flux strength and, therefore, induce significantly high eddy currents to the surrounded windings. Proximity effect also causes non uniform current density in the winding. Altogether, the inductor is affected by fringing fields, and proximity effect produces a very high AC resistance, consequently resulting in undesirable heat rise. Three winding designs based on electromagnetic field analysis are proposed to reduce the induced eddy currents and proximity effects in the windings. The results revealed a significant winding loss reduction of up to 56% in comparison with the original design.