Multi-mode electromechanical variable transmission

A drive system for a vehicle, comprising:

• a first gear set including a first sun gear, a first ring gear, a first plurality of planetary gears coupling the first sun gear to the first ring gear, and a first carrier rotationally supporting the first plurality of planetary gears;
• a second gear set including a second sun gear, a second ring gear, a second plurality of planetary gears coupling the second sun gear to the second ring gear, and a second carrier rotationally supporting the second plurality of planetary gears;
• a first electrical machine coupled to the first gear set;
• a second electrical machine coupled to the second gear set;
• a connecting shaft coupling an engine to the first gear set;
• a brake positioned to selectively limit a rotational movement of the second ring gear when engaged;
• a first clutch selectively rotationally coupling the first carrier and the second carrier to a driveshaft output of the vehicle when engaged;
• and
• a second clutch selectively rotationally coupling the second electrical machine to the connecting shaft and the engine when engaged,
• wherein the drive system is selectively reconfigurable into an intermediate shift mode of operation, in which the brake, the first clutch, and the second clutch are engaged.

A method of operating a multi-mode transmission of a vehicle, the method comprising:

• engaging a brake and first clutch of the multi-mode transmission to configure the multi-mode transmission into a first mode of operation whereby a first electromagnetic device is coupled to an engine and generates electricity to power a second electromagnetic device, the first clutch coupling a pair of carriers of a first planetary gear set and a second planetary gear set to a driveshaft output of the vehicle when engaged;
• engaging a second clutch of the multi-mode transmission to couple the engine and the second electromagnetic device, thereby configuring the multi-mode transmission into an intermediate shift mode;
• and
• at least one of (i) disengaging the brake to complete a reconfiguration of the multi-mode transmission into a second mode of operation and (ii) disengaging the second clutch to revert the multi-mode transmission into the first mode of operation from the intermediate shift mode.