Abstract: A DC/AC converter for converting DC power of a number of inductively connected generators into power grid conformal AC power for feeding into a connected power grid with a number of phases, includes an intermediate circuit with a positive and a negative intermediate circuit connection, and for each phase, a bridge. Each bridge includes a first switch between the positive intermediate circuit connection and a phase terminal, a second switch connected between a positive generator terminal of the generator and the phase terminal, a third switch connected between a negative generator terminal of the generator and the phase terminal, and a fourth switch between the negative intermediate circuit connection and the phase terminal.

Abstract: For monitoring an inverter that includes separate input-side connectors for multiple direct-current generators with regard to the occurrence of a critical fault current, differential currents in at last two pairs of input lines are measured separately in the inverter. The at last two pairs of input lines conduct the currents that are fed in at different input-side connectors, and all pairs of input lines in their entirety transmit all currents that are fed in at the connectors. The differential currents are compared with a limit value separately for each pair of input lines. A case of the limit value being exceeded is recognized as a fault. In addition, a sum of simultaneously occurring differential currents in all pairs of input lines is determined and the sum is compared with a further limit value, wherein a case of the further limit value being exceeded is also recognized as a fault.

Abstract: The disclosure relates to a method for operation of a photovoltaic installation for feeding electrical power into a medium-voltage power supply grid, with the photovoltaic installation having a plurality of photovoltaic modules, at least one inverter and at least one medium-voltage transformer, and with the primary side of the medium-voltage transformer being connected directly to an alternating-current (AC) low-voltage output of the inverter, and at least one direct-current (DC) switching member being arranged between the photovoltaic modules and a DC input of the inverter. When the electrical power produced by the photovoltaic modules in the photovoltaic installation is not sufficient for feeding electrical power into the supply grid, the photovoltaic modules are disconnected from an inverter on the DC voltage side while, in contrast, the inverter remains connected to the medium-voltage power supply grid on the AC voltage side by the medium-voltage transformer.

Abstract: For protecting a photovoltaic generator comprising photovoltaic modules, having an open circuit voltage higher than an insulation design voltage of its photovoltaic modules and being connected to an AC power grid via an inverter against a surge voltage relative to ground resulting from a ground fault and exceeding the insulation design voltage, the photovoltaic generator is surveyed for the occurrence of the ground fault or the surge voltage. Upon the actual occurrence of the ground fault or the surge voltage, at first, the photovoltaic generator is separated from an input-side intermediate link capacitance of the inverter, and the inverter is separated from the AC power grid. Then, the intermediate link capacitance is discharged via a resistor, prior to permanently closing semiconductor switches of an inverter bridge of the inverter and to reconnecting the photovoltaic generator to the input-side intermediate link capacitance of the inverter to short circuit the photovoltaic generator.

Abstract: A circuit arrangement for a photovoltaic inverter includes two bus lines, input terminals for connecting at least one photovoltaic generator to the bus lines, respectively, and at least one DC/AC converter connected to the bus lines. The circuit arrangement further includes a disconnector between each DC/AC converter and the bus lines, respectively, and at least one short-circuit path for short-circuiting a voltage between the bus lines, wherein a short-circuit switch is arranged in the short-circuit path, wherein the at least one short-circuit path runs between the bus lines upstream of all disconnectors between the input terminals and the disconnectors, and wherein the short-circuit switch in the at least one short-circuit path between the bus lines is connected in series with a fuse.

Abstract: A step-up converter includes a first inductance electrically connecting a first DC voltage input of the step-up converter to a first junction point, a step-up converter switch connecting the first junction point to a second DC voltage input and a second DC voltage output of the step-up converter, a first diode connecting the first junction point to a first DC voltage output of the step-up converter, and a snubber circuit comprising a charging path and a discharging path. The discharging path runs as a series connection of a capacitor and a second diode from the first junction point to the first DC voltage output, and the charging path is connected at its one end to a junction point between the capacitor and the second diode and is arranged such that the capacitor is charged when the step-up converter switch is switched on.

Abstract: The disclosure relates to a splash-water protection arrangement for a cooling air system of a housing of an electrical or electronic device having an air box having an air inlet grille and an air outlet opening through which air outlet opening ambient air sucked in at the front side exits the air box. The air inlet grille has a multiplicity of profiled strips that are arranged in at least two planes lying one behind the other in a main air inflow direction, wherein the profiled strips lying within a plane are spaced apart from one another and the profiled strips lying in the various planes overlap laterally.

Abstract: A short-circuit switch for use with a first electrical conductor and a second electrical conductor includes a controllable semiconductor switch that is configured to short-circuit a voltage present between the first conductor and the second conductor responsive to receipt of a trigger, and a mechanical press-pack structure. The controllable semiconductor switch is a press-pack-type thyristor having a first planar electrode and a second planar electrode on contact sides situated opposite one another. The thyristor is disposed in the mechanical press-pack structure. The mechanical press-pack structure includes: a first terminal electrode that is configured to connect the first planar electrode to the first conductor, wherein the first terminal electrode is resiliently supported by a spring assembly; and a second terminal electrode that is configured to connect the second planar electrode to the second conductor. The press-pack structure forms a protective cover enveloping the thyristor.

Abstract: An inverter has an inverter bridge connected between two DC busbars on the input side and connected to an AC output on the output side. The two DC busbars run, in a manner overlapping one another, in planes which are parallel to one another. The inverter bridge has a subcircuit having a plurality of semiconductor switches between the AC output and each DC busbar. Semiconductor modules which form the two subcircuits are connected, in a manner arranged beside one another, to the two DC busbars and to the AC output via connections. A connection element which leads to the AC output begins on that side of the DC busbar which faces the semiconductor modules in a region overlapped by the DC busbars and connects the semiconductor modules of the two subcircuits to one another there.

Abstract: The method of detecting an arc fault in a power circuit includes determining a first signal related to current flowing in the power circuit is determined and analyzing the first signal to determine whether the signal indicates the presence of an electric arc in the power circuit. In case the first signal indicates the presence of an electric arc in the power circuit, means for suppressing an electric arc are activated. A second signal related to current flowing in the power circuit is then determined and analyzed. An occurrence of an arc fault in the power circuit is signaled if the second signal does not indicate the presence of an electric arc. The system for detecting an arc fault is designed to perform a corresponding method.

Abstract: The disclosure relates to an electrical connection between two busbars made of flat conductors and an insulating layer disposed between the conductors at the opposite longitudinal edges of the two busbars. The two conductors of each busbar run parallel to each other at a distance on the longitudinal edge thereof, wherein a molded part made of electrically insulating material bridges the distances between the conductors of the two busbars. Electrically conductive contact elements, forced against each other but electrically insulated from each other, each contact one of the conductors of each busbar by means of structured contact surfaces and clamp the same between the element and the molded part, wherein the contact surfaces for the conductors of the two busbars including clamping protrusions running parallel to the longitudinal edges.

Abstract: For monitoring an inverter that includes separate input-side connectors for multiple direct-current generators with regard to the occurrence of a critical fault current, differential currents in at last two pairs of input lines are measured separately in the inverter. The at last two pairs of input lines conduct the currents that are fed in at different input-side connectors, and all pairs of input lines in their entirety transmit all currents that are fed in at the connectors. The differential currents are compared with a limit value separately for each pair of input lines. A case of the limit value being exceeded is recognized as a fault. In addition, a sum of simultaneously occurring differential currents in all pairs of input lines is determined and the sum is compared with a further limit value, wherein a case of the further limit value being exceeded is also recognized as a fault.

Abstract: The disclosure relates to a method for operating a photovoltaic system for feeding a medium-voltage grid, wherein the photovoltaic system has a photovoltaic generator including a plurality of photovoltaic modules, at least one inverter and at least one medium-voltage transformer. The medium-voltage transformer is connected on the primary side directly to a low-voltage AC output of the inverter, the inverter is connected to the photovoltaic generator via a DC input, and the inverter permits reverse currents from the low-voltage AC output to the DC input. The method is characterized by the fact that in the event that there is insufficient generation of electric power for the feed by the photovoltaic modules, the inverter remains connected on the AC side to the medium-voltage grid via the medium-voltage transformer, and remains connected on the DC side to the photovoltaic generator.

Abstract: For protecting a photovoltaic generator comprising photovoltaic modules, having an open circuit voltage higher than an insulation design voltage of its photovoltaic modules and being connected to an AC power grid via an inverter against a surge voltage relative to ground resulting from a ground fault and exceeding the insulation design voltage, the photovoltaic generator is surveyed for the occurrence of the ground fault or the surge voltage. Upon the actual occurrence of the ground fault or the surge voltage, at first, the photovoltaic generator is separated from an input-side intermediate link capacitance of the inverter, and the inverter is separated from the AC power grid. Then, the intermediate link capacitance is discharged via a resistor, prior to permanently closing semiconductor switches of an inverter bridge of the inverter and to reconnecting the photovoltaic generator to the input-side intermediate link capacitance of the inverter to short circuit the photovoltaic generator.

Abstract: A device for converting direct voltage from an electrochemical store or a fuel cell to alternating voltage, includes a two-stage design having a single DC/DC converter stage for generating an intermediate circuit voltage from the output voltage of the electrochemical store or the fuel cell, which converter stage converts, in particular raises, the direct voltage in a wide input voltage range directly to an intermediate circuit voltage with which a DC/AC converter stage can be operated to generate the alternating voltage. The single DC/AC converter stage generates the alternating voltage from the intermediate circuit voltage. The invention further relates to a method for actuating a device for converting direct voltage from a store or energy generator into alternating voltage for feeding into a supply network.

Abstract: A DC/AC converter for converting DC power of a number of inductively connected generators into power grid conformal AC power for feeding into a connected power grid with a number of phases, includes an intermediate circuit with a positive and a negative intermediate circuit connection, and for each phase, a bridge. Each bridge includes a first switch between the positive intermediate circuit connection and a phase terminal, a second switch connected between a positive generator terminal of the generator and the phase terminal, a third switch connected between a negative generator terminal of the generator and the phase terminal, and a fourth switch between the negative intermediate circuit connection and the phase terminal.

Abstract: An inverter with galvanic separation including a resonant converter and an upstream mounted boost chopper is intended to provide galvanic separation in the context of a variable input and output voltage as it exists in photovoltaic systems, with the efficiency being intended to be optimized over the entire input voltage range. This is achieved in that a boost chopper or a buck chopper is mounted upstream of the resonant converter.

Abstract: The method of detecting an arc fault in a power circuit includes determining a first signal related to current flowing in the power circuit is determined and analyzing the first signal to determine whether the signal indicates the presence of an electric arc in the power circuit. In case the first signal indicates the presence of an electric arc in the power circuit, means for suppressing an electric arc are activated. A second signal related to current flowing in the power circuit is then determined and analyzed. An occurrence of an arc fault in the power circuit is signaled if the second signal does not indicate the presence of an electric arc. The system for detecting an arc fault is designed to perform a corresponding method.

Abstract: The disclosure relates to a PV system including at least one inverter coupled to a grid via an AC disconnecting element and at least one transformer. The PV system includes at least one PV sub-generator having at least one PV string connected to a DC connection region of the inverter via DC lines. The PV system includes protection devices including a DC short-circuiting switch for short-circuiting the at least one PV string and a reverse-current protection element connected downstream thereof. The protection device includes an AC short-circuiting switch arranged upstream of the AC disconnecting element.

Abstract: Disclosed is a bi-directional battery power inverter (1) comprising a DC-DC converter circuit element (3) to which the battery (2) can be connected in order to generate an AC output voltage from a battery (2) voltage in a discharging mode while charging the battery (2) in a charging mode. The inverter (1) further comprises an HF transformer which forms a resonant circuit along with a resonant capacitor (6). In order to increase the efficiency of said battery power inverter, the transformer is provided with two windings (11, 12) with a center tap (20) on the primary side, said center tap (20) being connected to a power electronic center-tap connection with semiconductor switches (21, 31) while a winding (13) to which the resonant capacitor (6) is serially connected provided on the secondary side.