Normalized inductance modeling for ferrite power inductor families

This paper discusses a normalized inductance modeling approach for Ferrite Power Inductors (FPIs), aimed at facilitating the analysis of inductors performances and their selection in Switch-Mode Power Supply (SMPS) design. A normalized temperature-independent inductance versus current curve is proposed, to describe the saturation behavior of an entire family of inductors with different nominal inductances, made of different winding turns on the same magnetic core. A Normalized Operating Area (NOA) of the inductor family is consequently derived, allowing a quick identification of the normalized ranges of average inductor current and volt-second integral associated to the desired levels of a given performance of interest (e.g., the peak-to-peak inductor current ripple). By means of the NOA, it is possible to obtain the Real Operating Area (ROA) of each inductor, without performing additional simulations. Examples of application of the proposed modeling approach are provided for two FPI families, with shielded and unshielded magnetic cores of different ferrite materials.