Method of decoupling input and output torque for engine speed control and hybrid powertrain utilizing same

A hybrid powertrain for a vehicle comprising:

• a multi-mode transmission having an input member and an output member;
• a controller operatively connected to the multi-mode transmission and configured to execute a stored algorithm that includes a first stored transfer function relating virtual output torque to virtual input torque, and the first stored transfer function is based on modeled physical dynamics of a driveline of the vehicle for each selected mode of the multi-mode transmission;
• wherein, via the stored algorithm, the controller:
• commands the virtual input torque;
• and
• determines the virtual output torque required on the output member given the virtual input torque commanded on the input member for engine speed control in the selected mode of the multi-mode transmission such that rotational speed of the output member is unchanged to prevent undesired torque variation at the output member.

A vehicle comprising:

• a hybrid powertrain including:
• an engine having a crankshaft;
• a multi-mode transmission having an input member connectable to rotate with the crankshaft, and having an output member;
• and
• a controller operatively connected to the multi-mode transmission and configured to execute a stored algorithm that includes a first stored transfer function relating virtual output torque to virtual input torque, and the first stored transfer function is based on modeled physical dynamics of a driveline of the vehicle for each selected mode of the multi-mode transmission;
• wherein the modeled physical dynamics include spring functions, damper functions, and inertial mass values representative of components of the driveline in the selected mode, and are represented as a state space model;
• wherein, via the stored algorithm, the controller:
• commands the virtual input torque;
• and
• determines the virtual output torque required on the output member given the virtual input torque commanded on the input member for engine speed control in the selected mode of the multi-mode transmission such that rotational speed of the output member is unchanged to prevent undesired torque variation at the output member.