US Patent 9650032 Multi-mode electromechanical variable transmission

A vehicle includes an engine, a drive axle, a multi-mode transmission selectively coupled to the engine and the drive axle, and a controller coupled to the multi-mode transmission and configured to selectively configure the multi-mode transmission into an active neutral startup mode of operation in response to an engine start request. The multi-mode transmission includes a first gear set having a first planetary gear carrier and a second gear set having a second planetary gear carrier, a first motor/generator coupled to the first gear set, and a second motor/generator electrically coupled to the first motor/generator with a bus, coupled to the second gear set, and selectively coupled to the engine. The first gear set is coupled to the engine, and the first planetary gear carrier and the second planetary gear carrier are rotatably coupled.