Power converter, photovoltaic power generation system, method, and apparatus

A photovoltaic power generation system, comprising:

• a photovoltaic array;
• and
• a power converter comprising a power conversion circuit, a switching device, and a controller, wherein
• the power converter comprises N phases, wherein N is 2 or 3;
• an input end of the power conversion circuit is configured to connect to a direct current power supply, and the power conversion circuit is configured to convert a direct current output by the direct current power supply into an alternating current;
• the switching device comprises at least the following two stages:
• a first-stage switching device and a second-stage switching device, wherein the first-stage switching device and the second-stage switching device separately comprise N switches, and the N switches are connected in series to the N phases respectively;
• an output end of the power conversion circuit is connected to an alternating current power grid through the first-stage switching device and the second-stage switching device that are connected in series;
• and
• the controller is configured to:
• when the power conversion circuit is connected to the alternating current power grid, first control the N switches in the second-stage switching device to be simultaneously turned on, and then sequentially control the N switches in the first-stage switching device to be turned on one by one;
• wherein the photovoltaic array is connected to an input end of the power converter.

A method for controlling an action of a switching device, applied to a power converter, wherein the power converter comprises a power conversion circuit and a switching device;

• the switching device comprises at least a first-stage switching device and a second-stage switching device;
• the power converter comprises N phases, wherein N is 2 or 3;
• an output end of the power conversion circuit is connected to an alternating current power grid through the first-stage switching device and the second-stage switching device that are connected in series;
• and the first-stage switching device and the second-stage switching device separately comprise N switches;
• and
• the method comprises:
• when the power conversion circuit is connected to the alternating current power grid, first controlling the N switches in the second-stage switching device to be simultaneously turned on;
• and
• then sequentially controlling the N switches in the first-stage switching device to be turned on one by one.