Circuit and method for detecting insulation resistance of battery board to ground

Abstract

The invention discloses a battery panel ground insulation impedance detection circuit which comprises a partial pressure subcircuit and a voltage detection unit (11), wherein the partial pressure subcircuit is used for connecting between a positive electrode (PV+) of a battery panel and a negative electrode (PV-) of the battery panel. The partial pressure subcircuit comprises a first resistor (R1), a fourth resistor (R4) and a second control switch, the first resistor (R1), the fourth resistor (R4) and the second control switch are connected in series, the second control switch enables a to-be-detected electrode to be connected or disconnected with planet earth (PE) through opening and closing states, and forms a plurality of various connection combinations according to connection between the to-be-detected electrode and the planet earth, and the voltage detection unit (11) is used for sequentially outputting a plurality of sampling voltages according to each various connection combination. The partial pressure subcircuit is formed by respectively connecting resistors on a positive electrode impedance and a negative electrode impedance, the various connection combinations are formed under the control of the second control switch, the plurality of sampling voltages are output, positive electrode ground insulation impedance and negative electrode ground insulation impedance can be calculated, and the problem that when one electrode of a battery is infinite in ground impedance, ground impedance of the other electrode of the battery can not be calculated.

Description

technical field [0001] The present application relates to photovoltaic cell technology, and in particular, to a circuit and method for detecting the insulation resistance of a solar panel to ground. Background technique [0002] In photovoltaic inverter technology, photovoltaic panels are installed outdoors, and changes in the surrounding environment of the panels will affect the insulation resistance of the positive and negative electrodes of the photovoltaic panels to ground. Therefore, according to the current technical standards for most photovoltaic inverters connected to the grid, The photovoltaic inverter is required to detect the insulation resistance of the positive and negative poles of the solar panel to the ground before connecting to the grid, and then compare the detected impedance value with the minimum impedance required by the standard to determine whether the insulation resistance of the photovoltaic panel to the ground meets the safety grid connection. Req...

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Problems solved by technology

However, the above method has a disadvantage, that is, when the impedance of one pole to ground without an external resistance is infinite, the impedance of the other pole to ground cannot be calculated.

When the impedance of one pole is infinite, it obviously meets the requirements of CQC certification, but at this time, it is impossible to calculate the insulation resistance of the other pole to the ground according to the general circuit, and it is impossible to judge whether the insulation resistance of the photovoltaic panel to the ground meets the requirements of safe grid connection. Require

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