Direct current converter and photovoltaic system

A photovoltaic system, wherein the photovoltaic system comprises a plurality of direct current converters and a photovoltaic inverter;

• wherein a direct current converter in the plurality of direct current converters comprises a direct current conversion circuit, an auxiliary power supply, and a safe voltage output circuit, wherein an input end of the direct current conversion circuit is connected in parallel to an input end of the auxiliary power supply as an input end of the direct current converter, the input end of the direct current converter is configured to connect to a direct current power supply, an output end of the auxiliary power supply is connected to an input end of the safe voltage output circuit, and an output end of the safe voltage output circuit is connected in parallel to an output end of the direct current conversion circuit as an output end of the direct current converter;
• the auxiliary power supply is configured to:
• when the direct current conversion circuit does not perform voltage conversion, output a second voltage to the safe voltage output circuit based on a first voltage provided by the direct current power supply, wherein the second voltage is less than the first voltage;
• the safe voltage output circuit is configured to output a safe voltage based on the second voltage, wherein the safe voltage is less than the second voltage;
• an input end of each of the plurality of the direct current converters is configured to connect to a photovoltaic module, output ends of the plurality of the direct current converters are connected in series to an input end of the photovoltaic inverter, and an output end of the photovoltaic inverter is configured to connect to a power grid;
• and
• when direct current conversion circuits in the plurality of the direct current converters perform voltage conversion, the direct current conversion circuit in each direct current converter is configured to:
• perform voltage conversion on a direct current provided by the photovoltaic module, and output a first voltage;
• and the photovoltaic inverter is configured to:
• invert a first series voltage of the plurality of the direct current converters to an alternating current voltage, and supply power to the power grid, wherein the first series voltage is a sum of the first voltages at the output ends of the plurality of the direct current converters;
• or
• when the direct current conversion circuits in the plurality of the direct current converters do not perform voltage conversion, the output ends of the plurality of the direct current converters are connected in series to output a second series voltage, wherein the second series voltage is a sum of the safe voltages at the output ends of the plurality of the direct current converters.