A portable power supply includes an engine-driven generator that generates a first AC power. A rectifier rectifies the first AC power to a first DC power. A DC/DC converter converts a second DC power from a storage unit to a third DC power. A controller selectively enables one or both of the rectifier...http://www.google.ca/patents/US6943531?utm_source=gb-gplus-sharePatent US6943531 - Portable power supply incorporating a generator driven by an engine
