Photovoltaic inverter and leakage current detection apparatus

A photovoltaic inverter comprising:

• a device output end configured to connect to an alternating current power grid;
• an inverter circuit comprising an inverter output end;
• a magnetic ring;
• a first direct current power supply comprising a first direct current (DC) output end;
• a leakage current detection winding wound on the magnetic ring and comprising a first winding end and a second winding end;
• a connection line connecting the inverter output end and the device output end and passing through the magnetic ring;
• a modulation wave circuit comprising:
• a first push-pull circuit comprising:
• a first switching transistor comprising a first control end;
• and
• a second switching transistor comprising a second control end, wherein a series connection point of the first switching transistor and the second switching transistor is connected to the first winding end;
• a second direct current power supply;
• a leakage current sampling resistor comprising a first sampling resistor end and a second sampling resistor end, wherein the leakage current sampling resistor is coupled to the second winding end;
• and
• a comparator configured to output an inverted level signal when the leakage current detection winding is in a charging saturation status, wherein the comparator comprises:
• a positive input terminal coupled to the first winding end;
• a negative input terminal coupled to the second winding end;
• and
• a comparator output end coupled to the first control end, the second control end, and the first DC output end,
• wherein the first DC output end is configured to output a carrier signal, wherein the carrier signal comprises a first level signal and a second level signal that are alternating;
• and
• a filter circuit comprising input filter ends respectively connected to the first sampling resistor end and the second sampling resistor end, wherein the filter circuit is configured to filter a voltage signal at the first sampling resistor end and the second sampling resistor end based on the carrier signal in order to obtain a leakage voltage signal,
• wherein the first switching transistor is configured to be in an on-state when the comparator outputs the first level signal in order to control the first direct current power supply so that the leakage current detection winding is in a first charging state,
• wherein the second switching transistor is configured to be in an on-state when the comparator outputs the second level signal in order to control the second direct current power supply so that the leakage current detection winding is in a second charging state, and
• wherein a first current direction of the leakage current detection winding in the first charging state is opposite to a second current direction of the leakage current detection winding in the second charging state.