Power conversion device and DC power distribution system

A power conversion device comprising:

• a multiwinding transformer including a primary-side winding and a plurality of secondary-side windings;
• a primary-side DC terminal connected to a DC power supply;
• a plurality of secondary-side DC terminals;
• a primly-side bridge circuit connected between the primary-side DC terminal and the primary-side winding, the primary-side bridge circuit carrying out DC/AC power conversion;
• a plurality of secondary-side bridge circuits connected between the plurality of secondary-side windings and the plurality of secondary-side DC terminals, respectively, the plurality of secondary-side bridge circuits carrying out AC/DC power conversion;
• and
• a control device to control the primary-side bridge circuit and the plurality of secondary-side bridge circuits,
• the plurality of secondary-side windings including
• a first secondary-side winding strongest in magnetic coupling to the primary-side winding, and
• a second secondary-side winding weaker in magnetic coupling to the primary-side winding than the first secondary-side winding,
• wherein a leakage inductance between the primary-side winding and the second secondary-side winding is greater than a leakage inductance between the primary-side winding and the first secondary-side winding,
• the plurality of secondary-side DC terminals including
• a first secondary-side DC terminal electrically connected to the first secondary-side winding with a first secondary-side bridge circuit of the plurality of secondary-side bridge circuits being interposed, and
• a second secondary-side DC terminal electrically connected to the second secondary-side winding with a second secondary-side bridge circuit of the plurality of secondary-side bridge circuits being interposed, wherein the control device includes
• a first controller to control the primary-side bridge circuit so as to provide a first AC voltage having a reference phase,
• a second controller to control the first secondary-side bridge circuit so as to provide a second AC voltage having a first phase difference from the reference phase, and
• a third controller to control the second secondary-side bridge circuit so as to provide a third AC voltage having a second phase difference from the reference phase, and
• the first secondary-side DC terminal and the second secondary-side DC terminal supply output voltages different from each other,
• a rated output voltage of the DC power supply is substantially equal to a rated output voltage of the first secondary-side DC terminal, and
• a turns ratio between the primary-side winding and the first secondary-side winding is closer to one than a turns ratio between the primary-side winding and the second secondary-side winding.