Analysis and Control of A Full-Bridge Three-Level CLLC Resonant Converter

The bidirectional CLLC resonant converter has high potential in electric vehicles and energy storage systems for its advantages of soft switching and bidirectional power capability. In order to apply the CLLC resonant converter to medium and high voltage applications, this paper proposes a novel bidirectional full-bridge three-level (FBTL) CLLC resonant converter. The modulation strategy is proposed for the FBTL CLLC resonant converter, which has two operation modes in the first half cycle and the second half cycle, respectively. Then, neutral point voltage balancing control strategy without PI controller is proposed for the FBTL CLLC resonant converter. Furthermore, the frequency control of the FBTL CLLC resonant is presented to regulate the output voltage. Finally, a simulation model and a prototype converter are built to verify the feasibility and the advantages of the control for the proposed CLLC resonant converter.