The present invention relates to a two degrees-of-freedom compound planetary gear train with two conjoined planetary gear trains and four torque-transfer devices. The different combinations of states of various torque-transfer devices yield multiple modes of opration. The planetary gear train allows the addition of power of two prime-movers to drive the load. In addition it also allows splitting the power from one prime-mover into requirements of the energy storage system while catering to the output needs. This it achieves in a manner so as to limit the re-circulating power to a fraction of the input power. Other advantage of the transmission is that it provides a high overdrive ratio, which permits regeneration even at moderate speeds. The transmission obviates the need for a torque converter. The transmission can oprate as multi-speed, fully automatic.