Engine torque control during wheel shaft disconnect transitions on series hybrid powertrains

An engine torque control method for an electrified vehicle having a series hybrid powertrain with at least two electric traction motors, the engine torque control method comprising:

• detecting, by a control system of the electrified vehicle, an open-to-closed state transition of a drive shaft disconnect system based on a driver torque request, wherein the drive shaft disconnect system is configured to selectively connect and disconnect a first axle system or a pair of first wheels of the electrified vehicle from a first electric traction motor of the series hybrid powertrain;
• and
• in response to detecting the open-to-closed state transition:
• determining, by the control system, an optimum engine torque for the open-to-closed state transition based on a set of parameters for the open state of the drive shaft disconnect system;
• determining, by the control system, engine torque constraints for the open state and the closed state of the drive shaft disconnect system;
• applying, by the control system, the engine torque constraints to the optimum engine torque for the open-to-closed state transition to obtain a final engine torque command;
• and
• controlling, by the control system, an engine of the series hybrid powertrain based on the final engine torque command.