Method and device for measuring an insulation resistance of a DC voltage source connected to a split intermediate circuit in mains parallel operation
AssigneeSMA Solar Technology AG
InventorMartin Putz
Life of this patent
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Abstract
To measure an insulation resistance of a DC voltage source connected to a split intermediate circuit, a midpoint potential of the DC voltage source is shifted by different operation of two voltage converters by way of which two poles of the DC voltage source are each connected to one of two parts of the split intermediate circuit. A change in a residual current across all lines that carry a current flowing across the intermediate circuit from the DC voltage source, resulting from the shifting of the midpoint potential of the DC voltage source, is measured.
Claims23
A method for measuring an insulation resistance (Riso) of a DC voltage source connected to a split intermediate circuit, comprising:
- shifting a midpoint potential of the DC voltage source using a control circuit, and
- measuring a change (I_delta) in a residual current across all lines that carry a current flowing across the split intermediate circuit from the DC voltage source resulting from the shifting of the midpoint potential of the DC voltage source using a residual current detection device,
- wherein the midpoint potential of the DC voltage source is shifted by a different operation of two voltage converters in response to the control circuit by way of which two poles of the DC voltage source are respectively connected to a respective one of two parts of the split intermediate circuit, wherein the midpoint potential is shifted relative to a voltage midpoint of the split intermediate circuit between its two parts.
A device, comprising:
- a split intermediate circuit that comprises two parts, and a voltage midpoint between the two parts,
- two input terminals coupled to two poles, respectively, of a DC voltage source,
- two voltage converters, each connected on an input side thereof to a respective one of the two input terminals, and on an output side thereof to a respective one of the two parts of the intermediate circuit,
- a control device operably coupled to the two voltage converters, and
- a residual current detection device configured to detect a residual current across all lines that carry a current flowing across the intermediate circuit from the DC voltage source,
- wherein the control device is configured to shift, in an insulation resistance measuring mode, a midpoint potential of the DC voltage source connected to the input terminals relative to the voltage midpoint of the intermediate circuit by different operation of the two voltage converters, and
- wherein the residual current detection device is configured to detect a change in the residual current resulting from the shift of the midpoint potential of the DC voltage source.
Dependencies are inferred from the claim text.