Sma Solar Technology Ag

Tobias Mueller

Pablo Ignacio Correa Vasquez

Oliver Prior

Alexander Unru

Stephanie Coors

Sven Bremicker

Claus Allert

Henrik Wolf

Martin Bock

Christian Gehrke

Volker Wachenfeld

Sybille Pape

Harald Drangmeister

Karel De Brabandere

Florian Steiper

Thomas Ortmann

A method for determining capacitance values of capacitances of a photovoltaic system including a multiphase inverter which includes an output current filter on an alternating current side thereof and is connected to a multiphase energy supply network via a switching element and is associated with at least one intermediate circuit capacitance on the direct current side thereof is provided. The method includes disconnecting the photovoltaic system from the energy supply network by opening the switching element; operating the inverter to set up an island network after the disconnecting, wherein an in-phase AC voltage is applied to at least two outputs of an inverter bridge of the multiphase inverter and a flow of current is produced between the at least one intermediate circuit capacitance and at least one filter capacitance of the output current filter; measuring currents (Ia, Ib, Ic) flowing at the outputs of the inverter bridge and at least one voltage present at one of the capacitances, and determining a capacitance value of at least one of the capacitances using the determined voltage and the measured currents (Ia, Ib, Ic).

Method and inverter for determining capacitance values of capacitances of an energy supply system

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.

Determining a string configuration in a multistring-inverter

The disclosure relates to a method for operating an inverter that includes at least one bridge assembly that is actuated in a modulated manner for supplying electrical power to an energy supply network. Initially, the inverter is operated by the unipolar actuation of the at least one bridge assembly and the energy supply network is monitored for the presence of a network fault. If a network fault is detected, the inverter is operated at least at intervals by the bipolar actuation of the at least one bridge assembly. The disclosure further relates to a network fault-tolerant inverter which is equipped for carrying out the method.

Operating method for an inverter and grid fault tolerant inverter

A method for the operational control of an inverter designed for DC/AC voltage conversion that has at least one direct-voltage input and that can be connected to a power supply grid via at least one alternating-voltage output, the inverter being involved in a power flow interaction with the grid in such a manner that, during operation of the inverter, a leakage current Ican occur, wherein the leakage current Iis controlled in the operational control.

Method for the operational control of an inverter

The disclosure relates to a tracking method for a voltage transformer, in particular an inverter, of a photovoltaic system. In the method, an intermediate circuit voltage is repeatedly decreased or increased in one direction to a lower or higher voltage by voltage steps of a specified magnitude. The method is characterized in that an average rate of change of the intermediate circuit voltage in a partial time period between two voltage steps is limited by a maximum average rate of change, the maximum average rate of change being defined according to the magnitude of the intermediate circuit voltage. The disclosure further relates to a tracking device designed to perform the tracking method and to an inverter equipped with the tracking device.

Tracking method and tracking device for a voltage converter for a photovoltaic system

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.

Connecting an inverter in a solar power plant with shifted potential center point

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.

Growing community of inventors

Escherode, Germany

Tobias Mueller