Sma Solar Technology Ag

Sybille Pape

Marcel Kratochvil

Rainer Schmitt

Alexander Unru

Tobias Mueller

Neidhardt Bechtel

Torsten Otto

Moritz Welker

Tobias Müller

A method for detecting an arc in a circuit including a DC load, a DC source supplying the DC load, and a circuit arrangement between the DC source and the DC load is provided. 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 Δtand suppressed in an inactive time window with the second period Δt. Detection of a current I and/or a voltage U 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.

Method and circuit arrangement for detecting an arc, and photovoltaic (PV) inverter having a corresponding circuit arrangement

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 Δtand the power flow P is suppressed in an inactive time window with the second period Δt. Via detection of an input current Iflowing at the input and/or an input voltage Uapplied to the input and comparison of values of the input current Iand/or input voltage Udetected in the inactive time window with a current threshold value Ior a voltage threshold value Uan arc presence criterion is signaled if the input current Idetected in the inactive time window falls below the current threshold value Iand/or the input voltage Udetected in the inactive time window does not exceed the voltage threshold value U. The application also describes a circuit arrangement for detecting an arc and a photovoltaic (PV) inverter including such a circuit arrangement.

Method and circuit arrangement for detecting an arc and photovoltaic (PV) inverter having a corresponding circuit arrangement

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.

Method for three-phase supply into an alternating voltage network, and three-phase inverter

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.

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Vellmar, Germany

Sybille Pape