Design Methodology of Bidirectional LLC Resonant Converter

The conventional bidirectional LLC resonant converter encounters challenges in achieving the necessary extensive voltage gain range during backward mode due to its operation as a series-resonant converter. To address this issue, this study introduces a design methodology for a bidirectional LLC resonant converter. This methodology aims to achieve a consistent voltage gain curve, similar to that of a unidirectional LLC resonant converter, in both forward and backward modes. This is achieved by designing the resonant inductors based on a coupled inductor principle and reconfiguring the winding structure of the transformer. To validate the proposed converter design, an experimental prototype with a rated output power 3.6-kW is established.