Sma Solar Technology Ag

Thomas Wegener

Harald Drangmeister

Daniel Clemens

Marcel Kratochvil

Henrik Wolf

Holger Behrends

Michael Viotto

Johannes Lang

-Ing Henrik Wolf

The disclosure relates to a method for detecting an arc in a DC circuit. The method includes measuring and analyzing an AC component (I) of a current (I) flowing in the circuit and determining at least one parameter of the AC component (I). The level of a DC component (I) of the current (I) is varied and a degree of correlation between the level of the DC component (I) of the current (I) flowing in the DC circuit and the at least one parameter of the AC component (I) is determined. An arc is detected and selectively signaled based on the degree of the determined correlation. The disclosure also relates to an apparatus for carrying out the method and to an inverter comprising such an apparatus.

Method and apparatus for detecting an arc in a DC circuit

An inverter device for feeding electrical energy from a DC-power source into a power grid includes a pair of bus lines to be connected to the DC-power source; a plurality of capacitors connected in series between the bus lines; a surveying topology surveying an integrity of the plurality of capacitors, and to provide a signal indicating a loss of integrity of one capacitor of the plurality of capacitors; a voltmeter measuring a voltage drop over the plurality of capacitors; a DC/AC-inverter; and a controller. in case of the signal indicating a loss of integrity of one capacitor of the plurality of capacitors, the controller compares the voltage drop over the plurality of capacitors to a lost integrity threshold voltage value, and reduces a current load to the plurality of capacitors by reducing the power uptake of the DC/AC-inverter, when the voltage drop exceeds the lost integrity threshold voltage value.

Inverter device comprising a topology surveying a series of capacitors

A topology for surveying the integrity of a plurality of capacitors connected in series between a pair of bus lines arranged to be connected to a DC-power source comprises a plurality of resistors connected in series between the pair of bus lines, the plurality of resistors being connected in parallel to the plurality of capacitors; and a comparator comparing the electric potential of an intermediate point between two capacitors of the plurality of capacitors with the electric potential of an intermediate point between two resistors of the plurality of resistors. The comparator provides a signal signaling a difference between these two electric potentials, which indicates a loss of integrity of one capacitor of the plurality of capacitors.

Topology surveying a series of capacitors

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Kassel, Germany

Thomas Wegener