Abb Schweiz Ag

Hitachi Energy Switzerland Ag

Abb Power Grids Switzerland Ag

Michail Vasiladiotis

Tobias Geyer

Jan Svensson

Beat Buchmann

Georgios Stamatiou

Christoph Haederli

Alexandre Christe

Thomas Schaad

Bjoern Wider

An AC-to-AC modular multilevel converter (MMC) is configured to be connected between a three-phase AC system and a single-phase AC system. The MMC includes a number of converter arms connected in a ring to allow a circulating current to be circulated in the ring through each of the converter arms. Each converter arm includes series-connected converter cells. Phase terminals are arranged in the ring between the converter arms such that each of the converter arms is separated from neighboring converter arms by at least one of the phase terminals. The phase terminals include respective terminals for each of a first phase, a second phase and a third phase of the three-phase AC system and respective terminals for each of a positive conductor and a negative conductor of the single-phase AC system.

AC-to-AC MMC with reduced number of converter arms

A method of decoupled modulation of a direct AC/AC MMC between a first AC network L having a first waveform and a second AC network R having a second waveform includes performing first and second modulations based on respective reference signals of the first and second AC networks to generate, for each phase leg, first and second integer command signals corresponding to first and second combinations of cell states in the branches of the phase leg needed for generating the first and second waveforms. The method also includes, based on the first and second integer command signals, mapping to each branch a number of cell states to be used for concurrently generating both the first and second waveforms.

Modulation of AC/AC MMC

In a method of controlling a DC-to-AC Modular Multilevel Converter (MMC) having a three-phase AC side connected to a three-phase AC network and having a DC side connected to a DC network, the MMC has a double-star topology with a plurality of phase-legs. Each phase-leg has a first branch and a second branch. Each of the first and second branches includes a plurality of series connected converter cells. The method includes obtaining an Optimized Pulse Pattern (OPP) for the MMC. The method also includes adapting the OPP to the MMC by means of closed-loop pulse pattern control. The method also includes, based on the adapted OPP, sending firing signals to the plurality of cells of each branch.

Control of DC-to-AC modular multilevel converter

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Zurich, Switzerland

Michail Vasiladiotis