Abstract: A solar inverter is provided having a cooling module, a DC module, an inverter module and an AC module provided side-by-side within a chassis. The DC module includes an input accessible from a first side of the chassis and a disconnection switch on a second side of the chassis, with the input being configured to be connected to a DC solar power source. The AC module includes an output accessible from the first side of the chassis and a disconnection switch provided on the second side of the chassis. The cooling module is configured to pump a liquid coolant around the solar inverter in order to cool elements of the DC module, the inverter module and/or the AC module.

Abstract: An inverter for feeding a grid-compatible AC voltage into a grid is described, wherein the inverter includes an inverter bridge for converting a DC voltage to a first AC voltage and a grid interface between the inverter bridge and the grid for converting the first AC voltage to the grid-compatible AC voltage for feeding into the grid. An AC interface via which an AC module for feeding into the grid can be connected, is arranged between the inverter bridge and the grid interface.

Abstract: The invention relates to a process of connecting an AC output of a transformerless inverter of a solar power plant to an internal AC power grid at an input side of a galvanic isolation, while an offset voltage for shifting a potential center point of a photovoltaic generator connected to the inverter is applied. The process includes: (i) synchronizing the inverter with the power grid; (ii) essentially matching a potential center point of the current-carrying lines of the AC output and a potential center point of the power grid, while only one of the potential center points of the current-carrying lines and the power grid is yet shifted by the offset voltage; and (iii) galvanically connecting all current-carrying lines of the AC output with the power grid only after the steps of synchronizing and essentially matching.

Abstract: The disclosure relates to an apparatus including a multi-part housing to be assembled around two lines and conducting a power current generated by a solar module, and an electric circuitry arranged within the housing. The apparatus further includes connection devices for connecting the electric circuitry to the two lines such that at least one component of the electric circuitry is connected in parallel to the solar module. The connection devices include insulation displacement terminals which electrically contact the two lines, and at least one cutting blade made of an electrically insulating material cutting through at least one of the two lines in assembling the multi-part housing.

Abstract: A method for converting DC power from a source into AC power by means of an inverter which includes three bridge branches, each having a phase output, is described. During grid-connected operation, the bridge branches are actuated in such a way that the AC power is fed, as three-phase grid-compliant power, into a grid. During emergency operation of the inverter, the AC power is provided as single-phase island grid by two of the three bridge branches at the phase outputs thereof, wherein the inverter is disconnected from the grid.

Abstract: An inductor apparatus includes an inductor winding, a core defining a magnetic circuit for a magnetic flux generated by a current flowing through the inductor winding, at least one permanent magnet magnetically biasing the core by its permanent magnetization, and a magnetization device operable for adjusting a desired magnetization of the permanent magnet. The at least one permanent magnet is arranged within the magnetic circuit of the magnetic flux generated by the current flowing through the inductor winding. The magnetization device includes a magnetization winding and a circuitry configured to subject the magnetization winding to magnetization current pulses, thereby generating at a location of the permanent magnet a magnetic field which is able to change the permanent magnetization of the permanent magnet.

Abstract: An inverter for converting electrical power from a DC voltage generator is disclosed. The inverter includes a moisture sensor inside a housing of the inverter, and a control unit for controlling the inverter connected to the moisture sensor for receiving a moisture value from the moisture sensor. The inverter also includes a heating element connected to the control unit. The control unit is configured to control the inverter based on the moisture value such that, in the case where a limit value for the moisture is exceeded, the voltage at an input of the converter unit lies below an arc-avoiding voltage value and electrical power is fed to the heating element. Furthermore, a method for operating an inverter of this type is disclosed.

Abstract: For the purpose of determining a fault current component of a differential current which is measured as a current sum over a plurality of lines carrying a current of an AC current generator, an electric signal which depends on generator voltages present at the AC current generator with respect to earth potential and which is in phase with a leakage current component of the differential current is generated. The electric signal is scaled by multiplying it by a scaling factor; and the scaled electric signal is subtracted from the differential current to obtain a remainder. The scaling factor is repeatedly updated such that the effective value of the remainder reaches a minimum at the present value of the scaling factor.

Abstract: For connecting a PV array via an inverter to an AC power grid, at first a DC link at the input side of the inverter is pre-charged from the AC power grid. A link voltage of the DC link is adjusted to a pre-set value with the inverter connected to the AC power grid, the pre-set value being lower than an open circuit voltage of the PV array, and then the PV array at its open circuit voltage is directly connected to the DC link, while the link voltage is continuously adjusted to the pre-set value.

Abstract: A half-bridge of a bidirectional converter is divided into a first and a second conduction path connected in parallel. In each of the conduction paths a switching element and a freewheeling diode are connected in series, and the center points of the conduction paths are connected via a second inductor. The second inductor is connected in series with a first inductor which is connected to the center point of the second conduction path. The half-bridge has two operating modes. In each of the two operating modes the switching element in one of the two conduction paths is clocked at a high frequency to cause a flow of energy in one of two directions between a pair of high voltage-side connections and a pair of low voltage-side connections to the half-bridge. The two switching elements are of different types, the switching element in the first conduction path causing higher switching losses.

Abstract: An AC inductor includes a core, at least one permanent magnet for magnetically biasing the core, an inductor winding on the core, and a circuitry which guides an alternating current which flows through the AC inductor in such a way through the inductor winding that, during each half-wave of the alternating current, the alternating current generates a magnetization of the core which is opposite to the magnetization by the permanent magnet. This circuitry includes a commutator which guides the alternating current flowing between two contacts of the AC inductor through the same part of the inductor winding with a same flow direction during each of the half-wave of the alternating current.

Abstract: In large PV power plants, grounding of individual PV modules may lead to problems. The present invention overcomes such problems. The basis for the invention is a PV power plant comprising one or more PV generators, each comprising a PV string and an inverter with a DC input and an AC output. The PV string comprises at least one PV module and is electrically connected to the DC input of the inverter. The inverter comprises means for controlling the DC potential at the DC input depending on the DC potential at the AC output. The AC outputs of the inverters are coupled in parallel. The novel feature of the invention is that the PV power plant further comprises an offset voltage source, which controls the DC potential at the AC outputs. Thereby, the DC potential at the DC input will be indirectly controlled, and it is thus possible to ensure that the potentials with respect to ground at the terminals of the PV modules are all non-negative or all non-positive without grounding the PV modules.

Abstract: An inverter for converting a direct current flowing between two input lines into an alternating current flowing between two output lines includes first and second series circuits each including two switches configured to switch at a high frequency and of an inductance connected between the switches, wherein the two inductances are magnetically coupled. The inverter further includes diodes which lead from opposite sides of the inductances to a first intermediate point and diodes leading from a second intermediate point to the opposite sides of the inductances, and an unfolding circuit which forwards a direct current flowing between the intermediate points and consisting of sine-shaped half-waves to the output lines with a polarity changing half-wave by half-wave.

Abstract: For levelling the partial powers which flow at a grid connection point between a multi-phase AC power grid having a plurality of phase conductors and a unit for feeding electric energy into the AC power grid having a multi-phase inverter as well as electric consumer loads connected to the AC power grid, via the individual phase conductors, differences between the partial powers flowing via the individual phase conductors are determined and are reduced by feeding different partial powers with the inverter into the individual phase conductors.

Abstract: A method for determining a maximum power point (MPP) of a photovoltaic generator (PV) by variation of at least one parameter of search voltage and search current, within a maximally searchable search area on a power/voltage curve is disclosed. The method includes initializing by defining a start point with a start voltage and a start current, searching for the maximum power point (MPP) in at least one search direction by repeated variation of the search voltage or search current in the search area taking account of at least two limiting conditions for limiting the search area, wherein at least one of the limiting conditions for limiting the search area are is determined with evaluation of parameters provided in an operating state already attained during the search, and ending the search if one of the at least two limiting conditions for limiting the search area is met.

Abstract: A method and device to discharge a filter capacitance at the output of an inverter for feeding electrical power from a generation unit into a grid via a grid connect switch is disclosed. The grid connect switch has a generation unit side and a grid side, and via AC grid terminals on the grid side of the grid connect switch, the filter capacitance is connected to at least one of the AC grid terminals. A voltage applied across the filter capacitance is rectified independent of a polarity thereof, and a rectified voltage of a fixed polarity is provided, and a DC voltage link of a power supply unit for supplying power to circuitry of the inverter is charged with this rectified voltage.

Abstract: A circuitry arrangement for a solar power plant includes a transformerless inverter for feeding electric power from at least one photovoltaic generator into an alternating power grid, a galvanic separation of all lines carrying current between the inverter and the power grid, and a DC voltage source in an offset path between one electric line at the input side of the galvanic separation and a reference potential. The DC voltage source provides an offset voltage. The offset path includes a DC branch and an AC branch connected in parallel. The direct voltage source is connected in series with a current sensor in the DC branch, and at least one capacitor is arranged in the AC branch. Further, a DC contactor triggered by the current sensor is arranged in the offset path.

Abstract: A method for determining a spatial arrangement of photovoltaic module groups in a photovoltaic installation includes measuring a sequence of values of an illumination-dependent electrical characteristic variable of different photovoltaic module groups while the photovoltaic installation is subject to light incidence with an incidence intensity which varies over time and spatially. The relative spatial arrangement of the photovoltaic module groups with respect to one another is then determined by comparing sequences of measured values associated with different photovoltaic module groups.

Abstract: A method for limiting an output power of an inverter having an output bridge and an upstream boost converter includes determining a first measurement variable representative of a bridge temperature and a second measurement variable representative of an output power of the inverter. The method also includes determining a third measurement variable representative of a generator voltage at generator connections of the inverter or a fourth measurement variable representative of an output voltage at a power output of the inverter, and reducing the output power supplied to a power supply grid to a reduced power value. The reduced power value is determined based on the first measurement variable, the second measurement variable and at least one of the third and fourth measurement variables. A control device having such functionality is also disclosed.