More Symmetric Four-Phase Inverse Coupled Inductor for Low Current Ripples & High-Efficiency Interleaved Bidirectional Buck/Boost Converter

In order to substantially improve multiphase interleaved bidirectional buck/boost converter's (IBC) current ripples and efficiency, this paper proposes a more symmetric four-phase inverse coupled inductor (ICI) structure and its comprehensive design solution. First, this paper presents a more symmetric four-phase ICI structure which has the advantages of larger inductance values and more symmetric inductance parameters comparing to existing four-phase ICI of similar volume. Second, this paper presents the four-phase ICI's two magnetic circuit analytical models, the four-phase ICI's inductance calculation results from the two models are verified with Maxwell 3-D simulation and experiments. Third, this paper presents the four-phase ICI's comprehensive design solution with the two models and Maxwell 3-D piecewise linear transient simulation. Finally, the advantages of the four-phase ICI are verified with experiments. When the four-phase ICI is used in multiphase IBC, the IBC will have smaller current ripples, more symmetric phase current waveforms, lower output voltage ripple, and higher efficiency both in buck and boost modes.