Patent ID: 7723865

Claim:
A bidirectional buck boost DC-DC converter in which a direct-current power is supplied bidirectionally between two direct-current voltage sources of a primary-side power supply and a secondary-side power supply, the bidirectional buck boost DC-DC converter comprising: a primary-side converting unit that is connected to an input/output terminal of the primary-side power supply and performs a power conversion operation to the primary-side power supply; a secondary-side converting unit that is connected to an input/output terminal of the secondary-side power supply and performs a power conversion operation to the secondary-side power supply; a coupling unit that connects the primary-side converting unit and the secondary-side converting unit and mediates supply and reception of a power between the primary-side converting unit and the secondary-side converting unit; and a control unit that detects at least a voltage of the primary-side converting unit on a power supply side and a voltage of the secondary-side converting unit on a power supply side out of the voltage of the primary-side converting unit on a power supply side, the voltage of the secondary-side converting unit on a power supply side, and a voltage at an arbitrary point between a positive-electrode-side connecting terminal and a negative-electrode-side connecting terminal of the coupling unit each connecting the primary-side converting unit and the secondary-side converting unit, that detects a current flowing into/out of the primary-side converting unit, a current flowing into/out of the secondary-side converting unit, and a current flowing into/out of the coupling unit and controls so that a selected one of the currents is consistent with a command value corresponding to the selected one of the currents, and that controls a power conversion operation to the primary-side converting unit and the secondary-side converting unit based on the voltage of the primary-side converting unit on a power supply side that is detected, the voltage of the secondary-side converting unit on a power supply side that is detected, the selected one of the currents, and a signal based on the command value corresponding to the selected one of the currents so that a direction and a magnitude of a power flowing bidirectionally between the primary-side power supply and the secondary-side power supply are controlled to be continuously variable on instantaneous value basis regardless of a magnitude relation between a voltage of the primary-side power supply and a voltage of the secondary-side power supply in a state where the two direct-current voltage sources are each connected.