Power converter and control method

A method for controlling a power converter, the power converter including:

• a first DC terminal and a second DC terminal;
• a power converter circuit including a plurality of first switching elements and a plurality of second switching elements, the power converter circuit being implemented as a parallel connection of a plurality of switching circuits in each of which one of the plurality of first switching elements and a corresponding one of the plurality of second switching elements are connected one to one in series, the plurality of first switching elements being connected to the first DC terminal, the plurality of second switching elements being connected to the second DC terminal;
• a plurality of AC terminals provided one to one for the plurality of switching circuits, respectively, each of the plurality of AC terminals being connected to a connection node between the first switching element and the second switching element of a corresponding one of the plurality of switching circuits;
• a plurality of switches provided one to one for the plurality of switching circuits, each of the plurality of switches having a first terminal thereof connected to the connection node between the first switching element and the second switching element of a corresponding one of the plurality of switching circuits, the plurality of switches having their respective second terminals connected in common to a common connection node;
• a plurality of resonant capacitors provided one to one for the plurality of switches, respectively, each of the plurality of resonant capacitors being connected between the first terminal of a corresponding one of the plurality of switches and the second DC terminal;
• a resonant inductor having a first terminal and a second terminal, the first terminal of the resonant inductor being connected to the common connection node;
• and
• a capacitor connected between the second terminal of the resonant inductor and the second DC terminal,
• the method comprising:
• a first step including determining whether two-phase resonant currents corresponding to two switching circuits belonging to the plurality of switching circuits flow simultaneously through the resonant inductor;
• and
• a second step including performing, when determining, in the first step, that the two-phase resonant currents flow simultaneously through the resonant inductor, control of shifting respective ON periods of the first switching element and the second switching element in one switching circuit out of the two switching circuits.