US RE45,453 E1Granted

Inverter, more specifically for photovoltaic plants

AssigneeSMA Solar Technology AG

InventorsSven Bremicker, Frank Greizer, Matthias Victor

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Abstract

On an inverter (1) for converting an electric direct voltage, in particular of a photovoltaic direct voltage source into an alternating voltage with a direct voltage input with two terminals (DC+, DC−) and one alternating voltage output with two terminals (AC1, AC2) and with one bridge circuit including semiconductor switching elements (S1-S6), said bridge circuit comprising one first bridge branch (Z1) including four switching elements (S1-S4) and one second bridge branch (Z2) including two additional switching elements (S5, S6) as well as a freewheeling circuit provided with additional diodes (D7, D8), the efficiency is further increased without high frequency interferences and capacitive leakage currents having the possibility to occur on the generator side. This is achieved in that a respective one of the freewheeling diodes (D7, D8) forms a freewheeling branch together with a respective one of the switching elements (S2, S3) located in the first bridge branch (Z1), said freewheeling branch carrying a freewheeling current in a condition decoupled from the direct voltage.

An inverter for converting an electric direct voltage, more specifically of a photovoltaic direct voltage source, into an alternating voltage with a, the inverter comprising:

direct voltage input with two terminals between which there is provided;
a bridge circuit arranged in parallel,;
grid chokes being provided at the alternating voltage outputs of said bridge circuit, for connecting the bridge circuit to alternating output terminals;
and with an
alternating voltage output with two terminals,
characterized in that there is provided wherein
a first bridge branch with at least of the bridge circuit comprises four series connected first through fourth switching elements and a second bridge branch with at least one of the bridge circuit comprises a fifth and one a sixth switching element and that, between the alternating voltage terminal, which takes departure from said second bridge branch, and the,
a first connecting point between the second and the third switching elements in the first bridge branch is connected to a first alternating output terminal,
a second connecting point corresponding to between the fifth and sixth switching element provided elements in the second bridge branch and the respective is connected to a second alternating output terminal,
a third connecting points point between the first and the second or the third and the fourth switching element elements of the first bridge branch there is respectively connected one via a first diode in the direction opposite the forward direction so that a respective one of the central second or third switches of the first bridge branch and a respective one of the diodes carries a freewheeling current in a condition decoupled from the direct voltage to the second connecting point, wherein a cathode of the first diode is connected to the third connecting point, and
a fourth connecting point between the second and the third switching elements of the first bridge branch is connected via a second diode to the second connecting point, wherein an anode is connected to the fourth connecting point.

8 more elements

Abstract

Claims45