An Input-Series-Output-Parallel Connected Four-Switch Buck-Boost-Integrated CLLC DC Transformer with Bidirectional Natural Power-Sharing Property

This paper introduces an input-series-and-output-parallel (ISOP) connected two-stage modular four-switch Buck-Boost (FSBB)-integrated CLLC converter (FIC). This integrated FIC module not only improves system efficiency but also enhances the capability of soft-switching. Furthermore, by properly designing the resonant parameters and utilizing the proposed controller, natural power-sharing can be achieved. To regulate the output voltage, a PI compensator with input voltage feedforward is employed to adjust the duty cycle. Additionally, a maximum efficiency tracking algorithm is employed to find the optimal phase shift, thereby reducing system losses. Finally, simulations and experiments are conducted to validate the effectiveness of the proposed scheme.