Photovoltaic Ladder Inverter
This invention is for a unique DC-AC conversion topology for solar photovoltaic arrays that incorporates the best features of both central string inverters and DC-DC optomizers. It has a simple, elegant design with high reliability, high efficiency and low cost.
Techniques for DC-to-AC conversion are disclosed, and may be embodied in a solar inverter device that can operatively couple to a power grid. The device includes a photovoltaic (PV) stack including series-connected PV modules. Each PV module is associated with a capacitor for storing output of that PV module. A positive terminator circuit switches a negative end of the PV stack to ground during positive half of grid cycle, and a negative terminator switches a positive end of the PV stack to ground during negative half of grid cycle. A connecting branch couples each PV module output to a common bus, each branch including control circuitry configured to selectively couple the corresponding PV module output to bus.
During a first half of grid cycle, some of the capacitors discharge to the grid while a balance of the capacitors charge in preparation for discharge during a second half of grid cycle.
US 8,080,899 issued 2011-12-20 [MORE INFO
US 8,207,630 issued 2012-06-26 [MORE INFO
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