Patent ID: 7836986

Claim:
A method of operating a hybrid vehicle having first and second motor-generators, a combustion engine, first and second wheels and an energy storage device for powering said motor-generators, said method comprising: operating said vehicle in a low-speed mode when vehicle speed is below a threshold speed, said low-speed mode comprising driving one of said motor-generators by said engine to charge said energy storage device while said engine is decoupled from said first and second wheels and while the other one of said motor-generators provides mechanical power to one of said wheels using electrical power from said one motor-generator or from said energy storage device; when the vehicle speed exceeds said threshold, operating said vehicle in a high-speed mode comprising: (a) engaging said engine through disengagable coupling to said first wheel, engaging a selected one of said motor-generators to one of said wheels or to said engine, propelling said vehicle with mechanical power from said engine while operating said selected one motor generator as an electric generator to charge said energy storage device; (b) controlling the road speed of said vehicle by controlling a level of electric current generated by said selected one motor-generator so as to control a mechanical load of said selected one motor-generator on said engine.