Electric power conversion apparatus and method of controlling the same

An electric power conversion apparatus comprising:

• a transformer having a winding turn ratio 1:N between a primary side and a secondary side;
• a primary-side full bridge circuit provided at the primary side of the transformer;
• a first port connected with the primary-side full bridge circuit;
• a second port connected with a center tap at the primary side of the transformer;
• a secondary-side full bridge circuit provided at the secondary side of the transformer;
• a third port connected with the secondary-side full bridge circuit;
• and
• a control part configured to control the primary-side full bridge circuit and the secondary-side full bridge circuit in such a manner that regenerated power that is input from the first port is used to charge at least one of a first battery connected with the second port and a second battery connected with the third port, wherein
• the control part is configured to, when the control part has determined that a condition (VBd/N)≦VR≦(VBc/N) is met, further determine whether to use the regenerated power to charge the first battery and the second battery and, when the control part has determined that a condition VCd≦VR≦(VCc/Dmin) is met, further determine whether to use the regenerated power to charge the first battery, where
• VR denotes a voltage of the regenerated power, VCd denotes a discharge final voltage of the first battery, VCc denotes a charge final voltage of the first battery, VBd denotes a discharge final voltage of the second battery, VBc denotes a charge final voltage of the second battery, N denotes the winding turn ratio of the transformer, and Dmin denotes a lower limit of a duty ratio D of the primary-side full bridge circuit.