Parasitic Capacitance Modeling of Copper-Foiled Medium-Voltage Filter Inductors Considering Fringe Electrical Field

This article characterizes three parasitic capacitances in copper-foiled medium-voltage inductors. It is found that the conventional modeling method overlooks the effect of the fringe field, which leads to inaccurate modeling of parasitic capacitances in copper-foiled inductors. To address this problem, the parasitic capacitances contributed by the fringe electrical field is identified first, and a physics-based analytical modeling method for the parasitic capacitances contributed by the fringe electrical field is proposed, which avoids using any empirical equations. The total parasitic capacitances are then derived for three different cases with three different core potentials, from which a three-terminal equivalent circuit is derived, and thus, the parasitic capacitances in copper-foiled inductors are explicitly identified. The calculated results show a close agreement with the measured capacitance by using an impedance analyzer. Two recommendations for reducing the parasitic capacitances in copper-foiled inductors are given in this article.