Abstract: The disclosure relates to a method for connecting a photovoltaic installation to a power supply grid, the photovoltaic installation comprising a photovoltaic generator, a direct voltage intermediate circuit with at least one capacitor, and an inverter. The method including connecting the direct voltage intermediate circuit to the photovoltaic generator and the capacitor is pre-charged to a first voltage. The direct voltage intermediate circuit is then separated from the photovoltaic generator and the capacitor is discharged to or below a second voltage that corresponds to a maximum operating voltage of the inverter. The inverter is then connected to the power supply grid, an inverter bridge of the inverter is clocked, and the direct voltage intermediate circuit is connected to the photovoltaic generator.

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: 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: An inverter includes two input lines for connecting the inverter to an AC power source, a buffer capacitance effective between the input lines, a grounded potential equalization busbar, an isolation monitoring device monitoring the electrical isolation of one of the two input lines with regard to the potential equalization busbar, and an overvoltage eliminating device having at least one overvoltage eliminator for draining overvoltages from the input lines to the potential equalization busbar. The at least one overvoltage eliminator is connected between that input line, whose electric isolation with regard to the potential equalization busbar is monitored, and the potential equalization busbar, without any fuse being connected in series with the at least one overvoltage eliminator. Any overvoltage eliminator of the overvoltage eliminating device, which is connected between the other of the two input lines and the potential equalization busbar, if present, is connected in series with a fuse.

Abstract: A circuit with series-connected solar modules separated into a first and second substring, wherein each substring includes a first and a second terminal, and a solar inverter configured to supply electrical energy from the solar modules to an AC power grid. The circuit includes a first switch coupled to the first terminal of the first substring to a first power cable of the inverter, and a second switch coupled to the second terminal of the first substring to a first terminal of the second substring at a center point, thereby coupling the first and second substrings to form at least one string. The circuit further includes a third switch couple to second terminal of the second substring, and a shared actuator to open the first switch, second switch, and third switch if a current between the center point and a circuit ground exceeds a threshold value.

Abstract: A method of connecting a photovoltaic device to an AC power grid through an inverter includes monitoring a DC voltage at an input of an inverter, and activating the inverter when the monitored DC voltage exceeds a first predetermined threshold. The method further includes synchronizing an output voltage of the inverter with a grid voltage, connecting an output of the inverter to the AC power grid upon synchronization if the monitored DC voltage exceeds second predetermined threshold, and deactivating the inverter if a detected power being fed through the inverter falls below a predetermined power threshold while maintaining the connection between the output of the inverter and the AC power grid. Lastly, the method includes disconnecting the output of the deactivated inverter from the grid if the monitored DC voltage falls below a third predetermined threshold. Further, an apparatus that performs such functionality is also provided.

Abstract: A power converter arrangement configured to convert a direct voltage into an alternating voltage to be supplied to a grid includes a photovoltaic generator configured to generate the direct voltage, a voltage intermediate circuit, a main power converter connected in series with a bypass switch, a maximum power point controller configured to set a maximum power point voltage, and at least one voltage-limited additional circuit configured to be active during a start-up phase of the photovoltaic generator. The at least one voltage-limited additional circuit and the main power converter are configured as a voltage divider in parallel with the photovoltaic generator. The at least one voltage-limited additional circuit is configured as a capacitive voltage divider having a first capacitor and an intermediate circuit capacitor connected in series.

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 buck converter for converting a DC voltage at input terminals into an output voltage at output terminals is disclosed. The buck converter includes a DC voltage link including a series-connection of at least two capacitors between the output terminals, and one subcircuit per each capacitor of the series-connection. Each subcircuit includes an inductor and a freewheeling diode. A first one of the input terminals is connected to a first output terminal by a series-connection of a semiconductor switch and the inductor of a first one of the subcircuits, and the subcircuits are coupled for balancing the voltages across their inductors. The buck converter may be used upstream of an inverter bridge of an inverter, such that a maximum voltage at the input terminals may exceed a maximum voltage rating of the bridge switches within the inverter.

Abstract: A power converter circuitry for converting a DC voltage generated by a generator with varying output power in the mean voltage range into an alternating voltage for feeding into a grid, with several series-connected power converters, which are connected in parallel with said generator, as well as with a controllable bridging switch for each power converter, said bridging switch lying in a direct voltage intermediate circuit and bridging the respective power converter in the closed condition, is intended to be used for a photovoltaic generator. This is achieved in that a resistance chopper is connected between each power converter and the generator, no input diode being provided in the current path from the generator to the power converter, and that each bridging switch is connected in parallel with the resistance chopper in the direct voltage intermediate circuit.

Abstract: In a device for supplying electrical energy from a plurality of strings of photovoltaic modules to a power grid that includes a connection terminal for each string of the plurality of strings, wherein each connection terminal includes an over-current protection component including a power switch for selectively disconnecting the respective string. The device further includes a central insulation monitoring unit providing an insulation status of the entire plurality of strings, and the power switch of each over-current protection component includes an all-pole disconnecting power switch that can be opened and closed by a controller via a motor in response to the insulation status provided by the central insulation monitoring unit to select and selectively disconnect a string having an insulation failure. The device is further configured to supply electrical energy from the remaining strings of the plurality of strings having no insulation failure.

Abstract: A method of connecting a photovoltaic device to an AC power grid through an inverter includes monitoring a DC voltage at an input of an inverter, and activating the inverter when the monitored DC voltage exceeds a first predetermined threshold. The method further includes synchronizing an output voltage of the inverter with a grid voltage, connecting an output of the inverter to the AC power grid upon synchronization if the monitored DC voltage exceeds a second predetermined threshold, and deactivating the inverter if a detected power being fed through the inverter falls below a predetermined power threshold while maintaining the connection between the output of the inverter and the AC power grid. Lastly, the method includes disconnecting the output of the deactivated inverter from the grid if the monitored DC voltage falls below a third predetermined threshold. Further, an apparatus that performs such functionality is also provided.

Abstract: An inverter includes two input lines for connecting the inverter to an AC power source, a buffer capacitance effective between the input lines, a grounded potential equalization busbar, an isolation monitoring device monitoring the electrical isolation of one of the two input lines with regard to the potential equalization busbar, and an overvoltage eliminating device having at least one overvoltage eliminator for draining overvoltages from the input lines to the potential equalization busbar. The at least one overvoltage eliminator is connected between that input line, whose electric isolation with regard to the potential equalization busbar is monitored, and the potential equalization busbar, without any fuse being connected in series with the at least one overvoltage eliminator. Any overvoltage eliminator of the overvoltage eliminating device, which is connected between the other of the two input lines and the potential equalization busbar, if present, is connected in series with a fuse.

Abstract: A circuit arrangement in combination with a first string of series-connected solar modules separated into a first substring and a second substring is provided, wherein each substring includes a first terminal and a second terminal, and further in combination with a solar inverter configured to supply electrical energy from the solar modules to an AC power grid. The arrangement includes a first switch configured to selectively couple the first terminal of the first substring to a first power cable of the inverter, and a second switching circuit configured to selectively couple the second terminal of the first substring to a first terminal of the second substring at a center point, thereby coupling the first and second substrings to form the at least one string.

Abstract: The subject matter of the invention is a backup power system configured to be a UPS system, with a customer generation system and with a network monitoring device with a switch topology including a first connection node, that is connected to the customer generation system that is connected to at least one automatic disconnection switch including a first switch said first switch being disposed between the customer generation system and a utility grid, and that is connected to a second switch that is connected to one or several loads, said system including a second connection node that is connected to said second switch connected to said load, that is connected to a third switch disposed between the utility grid and the load and that is connected to a fourth switch to which there is connected a standalone inverter with a storage device, and said system including a third connection node, connecting said first switch and said third switch to said utility grid, said customer generation system supplying an AC volta

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.

Abstract: A power converter arrangement configured to convert a direct voltage into an alternating voltage to be supplied to a grid includes a photovoltaic generator configured to generate the direct voltage, a voltage intermediate circuit, a main power converter connected in series with a bypass switch, a maximum power point controller configured to set a maximum power point voltage, and at least one voltage-limited additional circuit configured to be active during a start-up phase of the photovoltaic generator. The at least one voltage-limited additional circuit and the main power converter are configured as a voltage divider in parallel with the photovoltaic generator. The at least one voltage-limited additional circuit is configured as a capacitive voltage divider having a first capacitor and an intermediate circuit capacitor connected in series.

Abstract: A device (1) for feeding electrical energy from an energy source with variable source voltage into an electric power supply network (15), said device (1) including a transformer (112) for galvanic isolation, a resonant inverter (11) with semi-conductor switches (a-d; A, B), one or several resonant capacitors (17; 18, 19; 20, 21) and one rectifier (113), is intended to provide high efficiency and have galvanic isolation. This is achieved in that the resonant inverter (11) is operated in the full resonant mode if the operating voltage is in an operation point (MPP) and in the hard-switching mode if the voltages exceed the operation point (MPP).

Abstract: A power converter circuitry for converting a DC voltage generated by a generator with varying output power in the mean voltage range into an alternating voltage for feeding into a grid, with several series-connected power converters, which are connected in parallel with said generator, as well as with a controllable bridging switch for each power converter, said bridging switch lying in a direct voltage intermediate circuit and bridging the respective power converter in the closed condition, is intended to be used for a photovoltaic generator. This is achieved in that a resistance chopper is connected between each power converter and the generator, no input diode being provided in the current path from the generator to the power converter, and that each bridging switch is connected in parallel with the resistance chopper in the direct voltage intermediate circuit.

Abstract: A device (1) for feeding electrical energy from an energy source with variable source voltage into an electric power supply network (15), said device (1) including a transformer (112) for galvanic isolation, a resonant inverter (11) with semi-conductor switches (a-d; A, B), one or several resonant capacitors (17; 18, 19; 20, 21) and one rectifier (113), is intended to provide high efficiency and have galvanic isolation. This is achieved in that the resonant inverter (11) is operated in the full resonant mode if the operating voltage is in an operation point (MPP) and in the hard-switching mode if the voltages exceed the operation point (MPP).