Design of a Highly efficient bidirectional isolated LLC resonant converter

The isolated unidirectional LLC resonant converter is known for its outstanding efficiency and high power density. Little information has however been published about the possibility of transferring power in the reverse direction. This paper presents modulation schemes for making the LLC converter bidirectional. High efficiencies are predicted for both directions of power flow, though, as the behavior of the resonant tank is substantially different in the reverse direction, some of the inherent benefits of the conventional LLC converter are lost.