Power conversion device

A power conversion device, comprising:

• a first input/output terminal pair;
• a second input/output terminal pair;
• a DC/DC converter connected to the first input/output terminal pair and the second input/output terminal pair;
• and
• a control unit configured to control the DC/DC converter,
• wherein the DC/DC converter comprises:
• a first switching leg having first and second switching elements connected in series via a first connection point and connected to the first input/output terminal pair;
• a second switching leg having third and fourth switching elements connected in series via a second connection point and connected in parallel to the first switching leg;
• a third switching leg having fifth and seventh switching elements connected in series via a third connection point and connected to the second input/output terminal pair;
• a fourth switching leg having sixth and eighth switching elements connected in series via a fourth connection point and connected in parallel to the third switching leg;
• a first energy storage and conversion unit connected to the first connection point and the second connection point and connected to one winding of a transformer and a first reactor connected in series;
• and
• a second energy storage and conversion unit connected to the third connection point and the fourth connection point and connected to the other winding of the transformer and a second reactor connected in series,
• wherein the control unit is able to execute a first control for causing the DC/DC converter to convert a voltage within a first range applied to the first input/output terminal pair into a voltage within a second range and to output the voltage within the second range from the second input/output terminal pair and a second control for causing the DC/DC converter to convert a voltage within the second range applied to the second input/output terminal pair into a voltage within the first range and to output the voltage within the first range from the first input/output terminal pair,
• wherein the first control is a control for controlling ON/OFF of each switching element in the DC/DC converter so that a state of the DC/DC converter iteratively transitions between, in an order of, a first state in which a current input from the first input/output terminal pair flows through the first reactor, a second state in which a current is able to circulate along a path including the first reactor, a third state in which the current input from the first input/output terminal pair flows through the first reactor in a direction opposite to a direction in the first state, and a fourth state in which a current is able to circulate along a path including the first reactor while flowing through the first reactor in a direction opposite to a direction in the second state, and
• wherein a transition from the second state to the third state and a transition from the fourth state to the first state are configured to be performed when a magnitude of a current circulating along the path including the first reactor has reached “0.”