Abstract: A method for three-phase infeed of electrical power from a DC source into a three-phase AC grid by means of an inverter includes measuring phase-specific grid voltages of the three-phase AC grid, and determining a grid frequency from the measured phase-specific grid voltages. The method also includes generating phase-specific voltage reference values from the phase-specifically measured grid voltages and the determined grid frequency, and generating phase-specific target current values using phase-specific predetermined target current amplitude values, the phase-specific voltage reference values and respective grid voltage amplitudes.

Abstract: The disclosure is directed to a method for detecting an arc in a direct-current circuit including a DC load, a DC source supplying the DC load, and a circuit arrangement arranged between the DC source and the DC load. A power flow between the DC source and an output of the circuit arrangement is cyclically interrupted by a switching circuit, such that the power flow is enabled in an active time window with the first period ?t1 and the power flow is suppressed in an inactive time window with the second period ?t2. Detection of a current I characterizing the power flow P and/or a voltage U characterizing the power flow P in two consecutive active time windows and comparison of the detected values of current I and/or voltage U of the active time window with the corresponding detected values from the preceding active time window can signal an arc if these values of the active time window differ from the corresponding values of the preceding active time window by more than a threshold value.

Abstract: The disclosure describes a method for detecting an arc in a direct-current (DC) circuit comprising a DC load, a DC source supplying the DC load, and a circuit arrangement arranged between the DC source and the DC load. A power flow P between an input and an output of the circuit arrangement is suppressed by means of a switching circuit through cyclical interruption such that the power flow P is enabled in an active time window with the first period ?t1 and the power flow P is suppressed in an inactive time window with the second period ?t2.

Abstract: A method for three-phase infeed of electrical power from a DC source into a three-phase AC grid by means of an inverter includes measuring phase-specific grid voltages of the three-phase AC grid, and determining a grid frequency from the measured phase-specific grid voltages. The method also includes generating phase-specific voltage reference values from the phase-specifically measured grid voltages and the determined grid frequency, and generating phase-specific target current values using phase-specific predetermined target current amplitude values, the phase-specific voltage reference values and respective grid voltage amplitudes.

Abstract: In operating an inverter including input connectors, (i) to which strings of photovoltaic cells are connected, (ii) each of which is connected via a DC/DC converter to a common DC voltage link, and (iii) which are bridgeable, the partial powers flowing through the individual DC/DC converters are determined, and for some time at least two DC/DC converters are either operated with the aim of balancing the partial currents flowing through them or connected through. During this operation or connecting through, the partial powers flowing through the at least two DC/DC converters are compared with each other, and if a difference between the partial powers exceeds a threshold value, the DC/DC converters are subsequently operated in a way adjusted to the fact that they connect different strings to the DC voltage link.

Abstract: In operating an inverter including input connectors, (i) to which strings of photovoltaic cells are connected, (ii) each of which is connected via a DC/DC converter to a common DC voltage link, and (iii) which are bridgeable, the partial powers flowing through the individual DC/DC converters are determined, and for some time at least two DC/DC converters are either operated with the aim of balancing the partial currents flowing through them or connected through. During this operation or connecting through, the partial powers flowing through the at least two DC/DC converters are compared with each other, and if a difference between the partial powers exceeds a threshold value, the DC/DC converters are subsequently operated in a way adjusted to the fact that they connect different strings to the DC voltage link.