Compact Switched-Inductor Power Supplies: Design Optimization with Second-Order Core Loss Model

Abstract

Expressing switched-inductor converter losses simply as a function of design variables is key for designers. Power losses in switched-inductor power supplies are varied in nature, and optimization schemes in the literature fail to account for all of them. Available core loss models are mostly empirical or rely on measurements or variables beyond the reach of power supply designers. Specifically, a simple core loss model is missing. This work offers complete design optimization of switched-inductor power supplies with a quadratic model of core loss that relies solely on design variables known to the designers—inductance and switching frequency (or inductor peak current). This model alleviates the burden of performing complex measurements to characterize the inductor—measurements that, moreover, require geometric data about the core, such as its size, which are often not disclosed by the manufacturer. Predicted minimum losses without approximation are within 3.2% of measured minimum losses, and predicted minimum losses with approximation are within 2.2% of measured minimum losses.