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

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 (LLC) resonant converters have gained popularity owning to its high efficiency feature. However, wide voltage gain range applications also challenge the LLC 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 LLC 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.