Abstract: An inverter including a circuit arrangement configured to measure an insulation resistance is disclosed. The inverter includes at least one half-bridge including at least two switching elements extending between respective end points, and a grid disconnection point comprising a series circuit comprised of two disconnection devices. The series circuit is arranged between a center point of the half-bridge and an AC voltage terminal of the inverter, which AC voltage terminal is configured to connect to a phase conductor or a neutral conductor of an AC voltage grid. The circuit arrangement includes a resistor and a voltage measurement apparatus. The resistor is arranged electrically in parallel with one of the disconnection devices and the voltage measurement apparatus is arranged electrically between the output-side terminal of the resistor and one of the end points of the half-bridge.

Abstract: A converter module for converting electrical power by means of a converter circuit having at least one power electronic semiconductor switch driven in a clocked manner is disclosed. The converter module includes a housing, a first DC link circuit terminal, and a capacitance arranged in the housing and connected to the first DC link circuit terminal and to the converter circuit and serving for stabilizing a DC voltage present at the first DC link circuit terminal. The converter module includes a second DC link circuit terminal, which is connected to the capacitance and to the first DC link circuit terminal, wherein the first and second DC link circuit terminals are designed for connection to DC link circuit terminals of further converter modules for converting electrical power. An inverter can be formed by at least two converter modules which are connected to one another via a respective one of their DC link circuit terminals.

Abstract: A description is given of an apparatus for disconnecting a connection between solar modules of a photovoltaic string. A circuit breaker, a band-stop filter and a supply circuit are arranged in a series circuit between a first and second terminal. The series circuit is configured to conduct a current that includes a DC string current flowing through the photovoltaic string and a high-frequency control signal modulated onto the DC string current. The supply circuit is configured to generate energy to power the apparatus from the DC string current. An AC bypass circuit bridges the circuit breaker in parallel and is configured to conduct the high-frequency control signal. A control unit is configured to operate the apparatus based on the high-frequency control signal. A reverse current diode oppositely polarized relative to an operating current flow is connected in parallel with the circuit breaker or the circuit breaker and the band-stop filter.

Abstract: A network subscriber unit for an electrical energy supply network includes a control unit configured to control the power exchange of the network subscriber unit with the energy supply network, a device configured to determine a voltage zero crossing at a connection point of the network subscriber unit with the energy supply network and a receiving unit of the network subscriber unit configured to receive a signal of a reference time. The control unit is in this case configured to determine a time offset between a time of the voltage zero crossing determined by the device and the received reference time and to control the power exchange based on the time offset.

Abstract: A circuit for limiting the voltage of a photovoltaic string divided into a first section and a second section of a series circuit of solar modules, includes a first terminal for connection to a first end of the first section, a second terminal for connection to a first end of the second section and a third terminal for connection to a second end of the second section. The circuit also includes a bypass switch, which is connected at one end to the first terminal and at the other end to the third terminal and a disconnect switch, which is connected at one end to the first terminal and at the other end to the second terminal. The circuit has a controller for actuating the bypass switch and the disconnect switch, wherein the controller is configured to determine a first threshold value UUL and a second, lower threshold value ULL depending on a switch voltage UOC dropped across the disconnect switch in an open state and taking into account the number of solar modules in the first section and in the second section.

Abstract: A method and associated device for detecting arcs in a photovoltaic system with an inverter and with a plurality of current collector circuits connected in parallel with the inverter via collector lines, wherein a plurality of strings of photovoltaic modules are connected in parallel with each current collector circuit via string lines. The method includes acquiring measured values of electrical variables and analyzing the measured values of the electrical variables for the presence of signs of an arc in the photovoltaic system using an analysis circuit and generating an arc signal which indicates the presence of an arc if the analyzed measured values meet predefined criteria. The method also includes acquiring measured values of acoustic variables using one or more acoustic sensors, and analyzing the measured values of the acoustic variables for the presence of signs of an arc in the photovoltaic system using the analysis circuit.

Abstract: A seal for an International Protection (IP)-sealing and electromagnetic capability (EMC)-shielding connection between a first housing component and a second housing component of an electrical or electronic device is disclosed. The seal includes an elastomer-containing sealing body and a metallic support that is embedded to some extent in the sealing body. The sealing body and the metallic support are connected to one another in an adhesive and/or form-fitting manner and thus form a material bond, and the metallic support has a plurality of contact segments, which project out of the sealing body and are configured such that the contact segments make electrical contact in resilient fashion with a first boundary surface that is assigned to the first housing component, and a second boundary surface that is assigned to the second housing component, the seal being pressed in between said boundary surfaces in an installed state.

Abstract: A description is given of an apparatus for disconnecting an electrical connection between solar modules of a photovoltaic string, the apparatus including a first and a second terminal for a respectively assigned solar module of the photovoltaic string, also a circuit breaker, a band-stop filter and a supply circuit for supplying energy to the apparatus, which are arranged in a series circuit with respect to one another between the first and second terminals. A bandpass filter for coupling out a high-frequency control signal from the electrical connection bridges the circuit breaker and the band-stop filter in parallel. In this case, a reverse current diode that is oppositely polarized relative to an operating current flow direction is connected in parallel with the circuit breaker or the partial series circuit comprising the circuit breaker and the band-stop filter.

Abstract: A method for operating a transformerless inverter includes operating first and second half-bridges of the inverter using a unipolar clocking method as a first clocking method, determining a value of a grid-frequency stray current at the DC terminals of the inverter during the unipolar clocking method, and when a limit value is exceeded by the stray current value, operating the first and second half-bridges of the inverter using a stray-current-reducing clocking method as a second clocking method in which the first half-bridge provides an AC voltage at the first AC output, wherein an amplitude of the AC voltage is less than 50% of the amplitude of a voltage amplitude of the grid, and the second half-bridge provides a difference voltage between the grid voltage and the voltage provided by the first half-bridge at the first AC output.

Abstract: An unfolding bridge includes a half-bridge with a first input terminal, a second input terminal, and an output terminal, wherein the half-bridge includes a first bridge switch connected between the first input terminal and the output terminal and a second bridge switch connected between the second input terminal and the output terminal. The unfolding bridge also includes a further half-bridge which includes a first further bridge switch connected between the first input terminal and a further output terminal and a second further bridge switch connected between the second input terminal and the further output terminal. A switch controller for operation of the bridge switches is designed such that a connection of the output terminals with the input terminals via the bridge switches is reversed at a zero crossing of an alternating current flowing at the output terminals.

Abstract: A method for detecting high-frequency AC currents in a DC circuit including a common mode choke with two partial windings includes tapping voltages dropping across the two partial windings due to the AC current, superposing the tapped voltages, and obtaining a superposed AC voltage wherein differential mode portions of the tapped voltages are summed constructively and common mode portions of the voltages are summed destructively; and measuring the superposed AC voltage.

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 present disclosure provides a control method for improving conversion efficiency of a multi-channel MPPT input inverter, which implements high efficient operation of the inverter.

Abstract: The disclosure relates to an inverter for supplying a power provided as a DC voltage at a DC input to an AC mains connectable to an AC output. In this case, the inverter includes a switching network with a plurality of semiconductor switches and a digital control unit for producing a digital switching pattern for digitally operated semiconductor switches of the switching network that are able to be used to produce a first output voltage (Uout,dig). The inverter additionally includes a linear control unit for producing signals for actuating at least one semiconductor switch of the switching network in a linear mode, wherein the linear control unit is set up to produce a voltage drop (Uout,lin) across and/or a current (Iout,lin) through the at least one linearly operated semiconductor switch to a target value that is dependent on an instantaneous difference between the first output voltage (Uout,dig) and a voltage (UAC) of the AC mains.

Abstract: A device for detecting alternating-current components iAC of an electric current iACDC flowing in a direct-current circuit includes an inductor arranged in the direct-current circuit, and an AC path arranged electrically in parallel with the inductor, wherein the AC path comprises a series circuit made up of a capacitor and a primary winding of a transformer. The device further includes a voltage measuring device, wherein a secondary winding of the transformer is connected to the voltage measuring device via a low-pass filter circuit.

Abstract: An inverter for converting DC power of a generator into grid-conforming AC power includes an inverter bridge circuit and a scanning circuit configured to trace at least one part of a characteristic curve of the generator to determine an MPP power value (PMPP). The scanning circuit is configured, in the case of a derating to a derated power (Pred), to trigger a tracing of the characteristic curve with provision of a first power profile deviating from the derated power (Pred) if an enable signal is present at the inverter, and to indicate a start and an end of the tracing by outputting a start signal and an end signal, respectively. The scanning circuit is further configured to provide a second power profile as AC power upon receiving a start signal, wherein the first power profile has a deviation from the derated power (Pred) with a sign that is opposite to a sign of a deviation of the second power profile from the derated power (Pred).

Abstract: A method and system for operating an inverter, which has a terminal with four conductor connectors for connection of the inverter to three outer conductors and to a neutral conductor of an AC voltage grid is disclosed. The method includes determining a connection configuration of the inverter to the AC voltage grid by actuating switching elements of a bridge circuit of the inverter to generate a zero-phase sequence system having a zero-phase sequence system current, and measuring and evaluating output currents of the inverter with respect to the zero-phase sequence system current. The method also includes identifying a presence of a connection of the neutral conductor to a conductor connector provided for connection to the neutral conductor when the zero-phase sequence system current exceeds a prescribed threshold value and identifying that the neutral conductor is not connected to the conductor connector provided for connection to the neutral conductor otherwise.

Abstract: An inductor assembly is disclosed that includes a magnetic core with a center leg and a number n of phase legs, wherein n is an integer and n>1. Each phase leg is magnetically connected to the center leg by an upper bridge and a lower bridge to form a magnetic main loop, a midpoint of the phase leg being magnetically connected to a center point of the center leg by a shunt element including a gap. Each phase leg further includes an upper inductor coil disposed on an upper phase leg section located between the midpoint and the upper bridge and a lower inductor coil disposed on a lower phase leg section located between the midpoint and the lower bridge. Alternatively, the upper and lower inductor coils are disposed on respective upper and lower bridges.

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.