Power Inductors Behavioral Modeling Revisited

This paper revisits the behavioral modeling of inductors used for Switch-Mode Power Supply (SMPS) design. A novel unified behavioral modeling for power inductors is herein proposed, which considers the DC current passing through the device and the equivalent applied voltage and switching frequency as model inputs, and the resulting peak-to-peak current ripple, total power loss and temperature as model outputs. The proposed behavioral modeling relies on simple analytical formulas, discovered from experimental measurements by using a multi-objective evolutionary algorithm. The resulting behavioral models allow to define the “Constrained Operating Area” of a power inductor, which describes the boundary area in the three-dimensional domain of switching frequency, DC current and equivalent voltage that can be applied to the component while maintaining its peak-to-peak current ripple, power loss and temperature within given limits. The experimental case studies presented in the paper eventually confirm the reliability of the proposed behavioral modeling approach and of the resulting models, in the assessment of the suitability of a given inductor and in the comparative evaluation among different inductors for a given SMPS application.