US Patent 9114804 Vehicle drive and method with electromechanical variable transmission

One embodiment provides a vehicle drive. The vehicle drive includes a first gear set and a second gear set. Each gear set includes a sun gear, a ring gear, planetary gears, and a planetary gear carrier. The vehicle drive includes a first motor/generator coupled to the sun gear of the first gear set. The vehicle drive includes a second motor/generator coupled to the planetary gear carrier or the ring gear of the first gear set. The second motor/generator is electrically coupled to the first motor/generator. The motor/generators are electrically coupled without an energy storage device. The vehicle drive includes an engine coupled to the ring gear of the first gear set and selectively coupled to the second motor/generator. The vehicle drive includes a first and a second clutch configured to selectively engage the second motor/generator to the planetary gear carrier of the first gear set or the engine.