Photovoltaic array ground insulation resistance online detecting system for high-power photovoltaic inverter

The invention provides a photovoltaic array ground insulation resistance online detecting system for a high-power photovoltaic inverter. A photovoltaic array positive bus PV+ is connected with one end of a resistor R1, and the other end of the resistor R1 is connected with the drain of a first MOSFET Q1, the source of the first MOSFET Q1 is connected with ground PGND, and a resistor R3 is further connected in parallel between the drain and the source of the first MOSFET Q1. A photovoltaic array positive bus PV- is connected with a resistor R2, the other end of the resistor R2 is connected with the source of a second MOSFET Q2, the source of the second MOSFET Q2 is connected with the ground PGND, and a resistor R4 is further connected in parallel between the drain and the source of the second MOSFET Q2. The drive connection end of the first MOSFET Q1 is connected with a first optic coupling drive circuit, and the drive connection end of the second MOSFET Q2 is connected with a second optic coupling drive circuit. The two ends of the R1, the PV+ and PGND end, the two ends of the R2 and the PV- and PGND end are connected into a first voltage sampling circuit, a second voltage sampling circuit, a third voltage sampling circuit and a fourth voltage sampling circuit respectively. The system is quick in reaction, small in consumption and wide in application range.