Backward Step-Up Control Strategy for Bidirectional LLC Resonant Converter

An LLC resonant converter has the advantages of simple structure and soft switching. It can enable bidirectional power transmission, but it is difficult to realize a normalized gain greater than one under backward mode (backward step-up mode). Cascaded dc/dc converters or topological changes solve this problem, additional switches components are required losses added. Without changing converter’s basic topology, paper proposes variable duty-cycle control strategy primary side for mode. Using control, LC tank be charged, then realized. Soft switching characteristics some all secondary guaranteed. In study, working principle an was analyzed, analyzed in detail. The voltage boundary continuous conduction (CCM) discontinuous (DCM) were derived. A synchronous rectification method related proposed. verified by experiments.