Sma Solar Technology Ag

Ralf Juchem

Matthias Victor

Andreas Falk

Marcel Kratochvil

Oliver Prior

Gerd Bettenwort

Alexander Unru

Dirk Hermeling

Tobias Müller

Oliver Frank

Juergen Schlabbach

Oliver Gotthold

A method and related apparatus for extending a DC voltage range of a rectifier circuit for the supply, from an AC grid, of a DC load which is connected to a DC rectifier output of the rectifier circuit, wherein an AC rectifier input of the rectifier circuit is connected via a grid connection point to the AC grid, wherein the rectifier circuit includes an AC/DC converter having an AC input and a DC output, wherein the AC/DC converter includes a converter circuit having semiconductor switches and freewheeling diodes connected in an antiparallel arrangement thereto, wherein an inductance is connected between the AC input of the AC/DC converter and the grid connection point. The method includes setting a desired DC operating voltage Uon the DC output of the AC/DC converter or on the DC rectifier output, or both, by an actuation of semiconductor switches of the AC/DC converter, wherein, when the desired DC operating voltage Ulies below a value of an amplitude Ûof an alternating voltage on the AC input of the AC/DC converter, the semiconductor switches of the AC/DC converter are actuated for an exchange of reactive power Q(t) with the AC grid, which has a voltage-lowering effect upon the amplitude Ûof the AC voltage at the AC input of the AC/DC converter, such that the amplitude Ûapproaches the desired DC operating voltage U, and wherein the exchange of the reactive power Q(t) with the AC grid is executed during or shortly before an electrical connection or an electrical isolation of the DC load to or from the rectifier circuit.

Method for extending a voltage range of a rectifier, rectifier for carrying out the method, and electrolysis system

A method of activating a Multi-String inverter for photovoltaic generators () of a photovoltaic plant (), the Multi-String inverter incorporating on the input side a separate DC-DC converter () for each generator string (photovoltaic generator) () and each output of the DC-DC converters () being connected in parallel and to an input of a DC-AC converter () and the DC-AC converter () being connected with an alternating current mains () for feeding into the mains aims at improving efficiency. This is achieved in that one or several electrical variables, namely input current, input voltage and/or input power are measured at each DC-DC converter () and at least one of the DC-DC converters () changing its operating condition as a function of this measurement when a limit value and/or a range is exceeded in such a manner that its power loss is reduced so that the energy yield of the photovoltaic plant () is increased.

Method for activating a multi-string inverter for photovoltaic plants

The subject matter of the present invention is a method for monitoring a photovoltaic generator () for generating current with a number of solar cells connected between two external connections by repeated feeding of a current with a frequency spectrum into the generator current circuit, detecting thereby a respective frequency response in the frequency spectrum with the supplied current as the input variable and an electric variable of the generator as the output variable, and detecting a change in the frequency response for monitoring the photovoltaic generator () in the event of a change during repeated feeding.

Method of monitoring a photovoltaic generator

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Niestetal, Germany

Ralf Juchem