Patent ID: 7309929

Claim:
A propulsion system, comprising: (a) a plurality of engine systems, each engine system comprising; an engine; a generator operable to convert mechanical energy output by the engine into electrical energy; an electrical converter operable to convert the outputted generator electrical energy into direct current electrical energy and to permit electrical energy to flow reversably in each of two directions; and (b) a direct current bus connecting the plurality of engine systems, the direct current bus being operable to carry the direct current electrical energy to and/or from the engine systems, wherein, at a selected time, at least a first engine system is turned off and at least a second engine system is turned on, wherein the electrical converter of the second engine is switched to provide electrical energy to the DC bus at a selected voltage level, and the electrical converter of the first engine is switched to receive electrical energy from the DC bus at a selected voltage level, whereby the first engine is activated using electrical energy supplied, via the DC bus, by the second engine.