Abstract: A power inverter system consists of a connection to a primary DC power source, a connection to an AC grid or load, a plurality of switching elements and filter elements to connect the DC power source to the AC grid or load, three power rails internal to the inverter, and a buck/boost circuit to provide a third power rail. The invention allows for simple transformerless grounded or ungrounded connection of a DC power source to an AC grid or load. The voltage rail that is not directly connected to the primary DC power source can be connected to an auxiliary DC power source without any significant additional hardware.

Abstract: A plant secondary power source consists of an auxiliary power source, an auxiliary converter, and a connection to a power generation plant DC voltage link. The auxiliary power source provides power control functionality without the use of direct communication between the auxiliary power system and the power generation plant.