Bidirectional DC-to-DC converter with inrush current suppression

A Direct Current (DC)-to-DC converter comprising:

• a first switching leg including a first switching device and a second switching device connected to each other;
• a second switching leg including a third switching device and a fourth switching device connected to each other;
• a first full-bridge circuit in which the first switching leg and the second switching leg are connected in parallel with each other and that converts direct current voltage from a first input/output terminal into alternating current voltage;
• a transformer;
• a first reactor, having one end connected to a node between the first switching device and the second switching device and another end connected to an end of a primary winding of the transformer;
• a third switching leg including a fifth switching device and a sixth switching device connected to each other;
• a fourth switching leg including a seventh switching device and an eighth switching device connected to each other;
• a second full-bridge circuit in which the third switching leg and the fourth switching leg are connected in parallel with each other and that converts direct current voltage from a second input/output terminal into alternating current voltage;
• a second reactor, having one end connected to a node between the fifth switching device and the sixth switching device and another end connected to a secondary winding of the transformer,
• wherein each of the switching devices has a respective capacitor connected in parallel;
• and
• a control unit that:
• controls power transmission by generating signals for driving the switching devices and adjusting a first phase difference between switching of the first full-bridge circuit and switching of the second full-bridge circuit, and
• when activated at start-up, switches one or more of a combination of the first switching leg and the second switching leg and a combination of the third switching leg and the fourth switching leg with a certain second phase difference and drives the first, third, fifth, and seventh switching devices or the second, fourth, sixth, and eighth switching devices with a first duty ratio, is the first duty ratio lower than a duty ratio during normal operation.