Patent ID: 7833119

Claim:
A vehicle powertrain comprising: an engine including an engine output member; a first motor/generator including a first rotor connected to the engine output member for rotation therewith; a transmission including a transmission input member selectively operatively connectable to the engine output member and the first rotor for rotation therewith, a transmission output member, a geartrain having a plurality of planetary gearsets with gear members that are configured to selectively operatively interconnect the transmission input member and the transmission output member, a second motor/generator including a second rotor operatively connected to one of the gear members for rotation therewith, and a plurality of torque transmitting devices that are selectively engageable to provide a plurality of fixed speed ratios between the transmission input member and the transmission output member that are independent of the speeds of the first and second motor/generators; and a control unit configured to selectively cause a series mode of operation characterized by the absence of a mechanical connection between the engine output member and the transmission output member and in which the second motor/generator provides torque to said one of the gear members; wherein the control unit is configured to cause the engine output member to provide torque to the first rotor whereby the first motor/generator generates electrical energy during the series mode of operation.