Variable Coupling Coefficient Integrated Inductor for Hybrid Energy Source Systems

Abstract

This paper proposes an innovative integrated inductor technology for hybrid energy source systems (HESS). The proposed inductor utilizes novel variable coupling coefficient integrated inductor (VCCII) technology to integrate two inductors that are required for a dual boost converter for HESS. VCCII has an integrated structure of two inductors, and enables control the coupling coefficient between the two inductors depending on the power distribution ratio of two power sources. In a low-power operation, the coupling coefficient between the two inductors is structurally zero, which enables the VCCII technology to independently control each output of energy sources without interference. In high-power operation, the coupling coefficient of the two windings increases by utilizing the non-linear characteristics of a magnetic core. These coupling effects peak shaving of the inductor current, which contributes to loss reduction and increase the maximum power capability. A prototype result verifies a 50% increase of peak power density and a 15% increase of maximum power capability under 20 V / 100 A and 25 V / 40 A inputs and 42 V output HESS. Additionally, the result gives 1.9 point of efficiency improvement in a double boost converter circuit operating at 100-kHz switching, 810 W output.