Electric power converter and control method for electric power converter

An electric power converter comprising:

• a switching unit that includes a plurality of first bidirectional switches disposed between a DC power source and an AC load or between a DC load and an AC power source;
• a controller configured to control the switching unit to perform power conversion between DC power and AC power;
• and
• a second bidirectional switch that is disposed on a path between one pole of the DC power source or one pole of the DC load and the switching unit to perform connection and interruption between the one pole of the DC power source or the one pole of the DC load and the switching unit, wherein
• the controller turns on one of the plurality of first bidirectional switches connected between another pole of the DC power source and the AC load or between another pole of the DC load and the AC power source when turning off the second bidirectional switch,
• the plurality of first bidirectional switches include a third bidirectional switch that connects between the another pole of the DC power source and one end of the AC load or between the another pole of the DC load and one end of the AC power source and a fourth bidirectional switch that connects between the another pole of the DC power source and another end of the AC load or between the another pole of the DC load and another end of the AC power source,
• the controller, when the second bidirectional switch turns off, turns off one of the third and fourth bidirectional switches and turns on the other of the third and fourth bidirectional switch based on a voltage polarity of the AC load or a voltage polarity of the AC power source,
• the switching unit includes:
• first and second DC nodes provided on a side of the one pole of the DC power source or the one pole of the DC load;
• a third DC node provided on a side of the another pole of the DC power source or the another pole of the DC load;
• and
• two AC nodes provided on a side of the AC load or the AC power source,
• the plurality of first bidirectional switches are disposed to connect each of the first to third DC nodes and each of the AC nodes, and
• a reactor is provided between the first DC node and the second DC node.

A control method for an electric power converter comprising:

• connecting between a DC power source and an AC load or between a DC load and an AC power source by controlling a switching unit and a second bidirectional switch that is disposed on a path between one pole of the DC power source or one pole of the DC load and the switching unit, the switching unit including a plurality of first bidirectional switches that connect between the DC power source and the AC load or between the DC load and the AC power source;
• turning off the second bidirectional switch;
• turning on one of the first plurality bidirectional switches that connects between another pole of the DC power source and the AC load or between another pole of the DC load and the AC power source when the second bidirectional switch is off;
• and
• turning off the one of the first plurality bidirectional switches when the second bidirectional switch is on, wherein
• the switching unit includes:
• first and second DC nodes provided on a side of the one pole of the DC power source or the one pole of the DC load;
• a third DC node provided on a side of the another pole of the DC power source or the another pole of the DC load;
• and
• two AC nodes provided on a side of the AC load or the AC power source,
• the plurality of first bidirectional switches are disposed to connect each of the first to third DC nodes and each of the AC nodes, and
• a reactor is provided between the first DC node and the second DC node.