Multilevel power conversion system, and circuitry of multilevel power conversion system

Circuitry of a multilevel power conversion system comprising:

• a multilevel power converter that comprises:
• a positive terminal and a negative terminal connected to a DC power supply or a DC load;
• a plurality of DC capacitors connected in series via a DC neutral point between the positive terminal and the negative terminal;
• an AC terminal connected to an AC power supply or an AC load;
• a first semiconductor switching element and a fourth semiconductor switching element connected in series via the AC terminal between the positive terminal and the negative terminal to have the same polarity;
• a first freewheeling diode and a fourth freewheeling diode respectively connected in inverse parallel to the first semiconductor switching element and the fourth semiconductor switching element;
• a third semiconductor switching element and a second semiconductor switching element connected in series between the DC neutral point and the AC terminal to have reverse polarity;
• and
• a third freewheeling diode and a second freewheeling diode respectively connected in inverse parallel to the third semiconductor switching element and the second semiconductor switching element, wherein
• the circuitry is configured to:
• cause an operation mode of the multilevel power converter to transition to a standby mode in which power conversion is not performed between the positive terminal and the AC terminal based on a predetermined condition;
• and
• generate and output a gate signal that puts at least one of the third semiconductor switching element or the second semiconductor switching element into a conducting state or a switching state in the standby mode.