MULTIMODE ELECTROMECHANICAL VARIABLE SPEED TRANSMISSION AND METHOD OF DESIGNING, PRODUCING AND OPERATING THE SAME

The invention discloses a multi-mode electro-mechanical variable speed transmission capable of providing multiple operation modes including two power split operation modes and at least one fixed output-to-input speed ratio operation mode. The transmission includes an input shaft, an output system, at least one planetary gear set having at least a first, second and third co-axial rotatable components, two electric machines, and at least one torque transfer device including a neutral position and at least two engagement positions. The first co-axial rotatable component couples to the first electric machine with a constant speed ratio; the second co-axial rotatable component couples to the output system with a constant speed ratio; and the third co-axial rotatable component couples to the input shaft with a constant speed ratio; the second electric machine selectively couples to two different co-axial rotatable components of the planetary gear set with two different speed ratios. The transmission further includes a means for unloading the torque transfer device, a means for adjusting engine power, and a means for shifting one of the electric machines to a freewheeling state and actively synchronizing the speed of the electric machines with the speed of one of the engagement positions of the torque transfer device.