Variable Coupling Coefficient Integrated Inductor

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 for a dual-boost converter for HESS. VCCII has an integrated structure of two inductors that enables the control of the coupling coefficient between the two inductors depending on the power distribution ratio of two power sources. With a low power demand, the coupling coefficient between the two inductors was zero, which enabled VCCII to independently control each output of the energy source without interference. With a high power demand, the coupling coefficient of both windings increased by utilizing the nonlinear characteristics of a magnetic core. These coupling coefficients yield a peak shaving of the inductor current, which contributed to the loss reduction of switching device and increased maximum power capability of HESS. The experimental results from a prototype showed a 50% increase in the peak power density and a 15% increase in the maximum power capability under the inputs of 20 V / 100 A and 25 V / 40 A and output of 42 V for the HESS. The system efficiency was evaluated in the double-boost converter circuit operating at 100-kHz switching HESS system. The results showed a 1.9% efficiency improvement at the output of 810-W, and confirmed the smooth power distribution control between two power sources in the HESS with an overall efficiency of 96.5%.