A Novel Approach to Calculate the Reluctance of Air-Gaps in Ferrite Cores

Magnetic circuit theory is a reasonable approach to quickly estimate the inductance. The air-gap reluctance strongly depends on air-gap size, shape and position. Several calculation methods have been proposed that improve the equivalent representation of the air-gap in the magnetic circuit. However, those approaches either have been restricted to small air-gaps or are not valid for arbitrary air-gap position or shape. This paper introduces a novel approach to quickly predict the air-gap reluctance as a function of air-gap size, shape and position. Special attention is paid to the reluctance of large air-gaps as well as inductors with discretely distributed air-gaps.