Power split hybrid transmission having synchronized disconnect shift element

A method of controlling a power split hybrid transmission for a vehicle, the power split hybrid transmission including an internal combustion engine (ICE) that drives an output shaft that is rotatably coupled to a planetary carrier of a planetary gear set, the planetary gear set further including a sun gear and a ring gear, a first electric motor that is rotatably coupled to the sun gear and that provides a first rotatable input through the ring gear that drives a first ratio counter gear to a transmission output shaft, a second electric motor that is rotatably coupled to a second ratio counter gear that provides a second rotatable input to the transmission output shaft, a disconnect clutch positioned between the transmission output shaft and a transfer case input shaft of a transfer case, the transfer case driving a transfer case output shaft that delivers a drive torque to drive wheels, wherein the disconnect clutch disconnects rotatable motion from the transmission output shaft to the transfer case input shaft, the method comprising:

• receiving a target engine speed signal and an actual engine speed signal for the ICE;
• outputting a first engine speed control torque command signal for the first electric motor and a second engine speed control torque command signal for the second electric motor based on the target engine speed signal and the actual engine speed signal;
• receiving a transmission output target speed signal and an actual transmission output speed signal for a transmission output shaft;
• outputting a first transmission control torque command signal for the first electric motor and a second transmission control torque command signal for the second electric motor based on the transmission output target speed signal and the actual transmission output speed signal;
• determining whether the ICE, the first electric motor and the second electric motor are disconnected from the drive wheels;
• commanding, based on a determination that the ICE, the first electric motor and the second electric motor are disconnected from the drive wheels, a final first torque to the first electric motor based on the first engine speed control torque command signal and the first transmission output speed signal;
• and
• commanding, based on a determination that the ICE, the first electric motor and the second electric motor are disconnected from the drive wheels, a final second torque to the second electric motor based on the second engine speed control torque command signal and the second transmission output speed signal, wherein the final first and second torque are determined to match a speed of the transmission output shaft with the transfer case output shaft such that no effective input torque is provided from the transmission output shaft during a range shift of the transfer case.