A Novel LLC Converter With Topology Morphing Control for Wide Input Voltage Range Application

Abstract

Wide voltage gain range applications are challenging for dc/dc converters, and the system efficiency would be degraded in order to satisfy the voltage gain requirement. Inductor–inductor–capacitor ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> ) resonant converters have gained popularity owning to its high efficiency feature. However, wide voltage gain range applications also challenge the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converters from the following three aspects: 1) large switching frequency operating range is required to meet the voltage gain requirement, which degrades the converter electromagnetic interference (EMI) performance and challenges the optimization of magnetic components; 2) small inductor ratio is required to boost the voltage gain, which increases the resonant tank root-mean-square (rms) current and conduction loss; and 3) control instability issues may occur at both maximum voltage gain and minimum voltage gain, which reduce the converter reliability. To address these issues, in this article, a novel <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter with topology morphing control is proposed for wide voltage gain range applications. Three operation modes, dual full-bridge (DFB), hybrid full-bridge and half-bridge (HFBHB), and dual half-bridge (DHB), can be achieved by adopting the topology morphing control, which can cover a wide voltage gain operation range. Operational principles, design considerations, and experimental validations of the proposed converter are presented.