Patent ID: 8525492

Claim:
An apparatus, comprising: an internal combustion engine; a first variable speed generator driven by the engine; a second variable speed generator driven by the engine; a first inverter to convert variable electric power from the first variable speed generator to provide a first controlled AC voltage at a first electrical output node; a second inverter to convert variable electric power from the second variable speed generator to provide a second controlled AC voltage at a second electrical output node, the first inverter and the second inverter being electrically connected together with a common electrical node to provide a third controlled AC voltage across the first output node and the second output node greater than each of the first controlled AC voltage and the second controlled AC voltage; and a switching device to receive the first controlled AC voltage, the second controlled AC voltage, and AC power from an external power source, wherein the switching device is structured to supply the first controlled AC voltage to the first electrical output node and to supply the second controlled AC voltage to the second electrical output node when AC power from the external power source is below a threshold value.