A High-Efficiency Single-Mode Dual-Path Buck-Boost Converter With Reduced Inductor Current Donghee Cho

Abstract

This article presents a single-mode dual-path buck- boost converter (SDBBC) for mobile devices powered by lithium- ion batteries. Unlike the conventional buck-boost converter (CBBC), this SDBBC conducts buck and boost operations using a hybrid structure with two flying capacitors ( C F1, CF2)a n do n e inductor. This hybrid structure eliminates any mode transition between circuit configurations, covering both the buck and boost operations continuously within a single-mode operation. By con- sistently connecting the inductor to the load with a secondary path formed by C F1 and CF2, the average of the inductor current (IL ) is always smaller than the load current ( ILOAD)a c r o s sa l lt h e output voltage conversion ratios, thus incurring low conduction loss and switch transition loss. Also, the current delivered to the load increases as the duty ratio increases, so the right half-plane (RHP) zero is removed. Therefore, the proposed SDBBC achieves high power efficiency seamlessly across the whole conversion range, 94.8% peak efficiency is achieved even with an inductor of 175 m /Omega1dc resistance (DCR), and 95.58% efficiency is achieved in the boost operation at a heavy load current of 1 A using a large size inductor with 19 m /Omega1DCR.