Transformerless static voltage inverter for battery systems

A static inverter for at least one multicell DC source battery of elementary DC source cells electrically connected in series and including a number N of intermediate voltage taps along the elementary DC source cells electrically connected in series, comprising:

• a number of elementary DC source cells between an intermediate tap and one of another adjacent intermediate tap and an end terminal of said number of elementary DC source cells is proportionate to an amplitude in a respective phase interval of a number N of discretization phases of a waveform of the AC voltage to be output in a quadrant;
• and comprising:
• a number N of power switches each connecting a respective intermediate tap and a first end terminal of a first polarity of said chain of elementary DC source cells electrically connected in series to a common circuit node of said first polarity;
• an output bridge stage constituted by at least four power switches controlled in pairs for switching current paths through the output bridge stage, having a first pair of nodes coupled to said common circuit node of said first plurality and to the other end terminal of polarity opposite to said first polarity of said elementary DC source cells electrically connected in series, respectively, and a second pair of nodes constituting an AC output;
• a control circuit sequentially and cyclically turning on, in a continuous manner, one switch at a time of said N power switches;
• each for a phase interval of 1/(4N) times a period of said AC output, and alternately turning on by pairs said at least four power switches of said output bridge stage at every half a period of said AC output.

A system for powering electric loads at a certain AC voltage from a solar energy conversion system comprising:

• at least one photovoltaic panel;
• at least one redox flow battery for storing energy comprising a plurality of elementary DC source cells electrically connected in series and having a number N of intermediate voltage taps along a number of DC source cells composed of said elementary the elementary DC source cells electrically connected in series;
• and
• an inverter for outputting electric power at said AC voltage, wherein the number of elementary DC source cells comprised between an intermediate tap and another adjacent intermediate tap or an end terminal of elementary DC source cells electrically connected in series is proportionate to an amplitude in a respective phase interval of a number N of discretization phases of a waveform of the AC voltage to be output in a quadrant;
• and comprising
• a number N of power switches each connecting a respective intermediate tap and a first end terminal of a first polarity of said number of elementary DC source cells electrically connected in series to a common circuit node of said first polarity;
• an output bridge stage constituted by at least four power switches controlled in pairs for switching current paths through the output bridge stage, having a first pair of nodes coupled to said common circuit node of said first polarity and to the other end terminal of polarity opposite to said first polarity of said chain of elementary DC source cells electrically connected in series, respectively, and a second pair of nodes constituting an AC output;
• a control circuit sequentially and cyclically turning on, in a continuous manner, one switch at a time of said N power switches;
• each for a phase interval of 1/(4N) times the period of said AC output, and alternately turning on by pairs said at least four power switches of said output bridge stage at every half a period.