Abstract:
A powertrain system includes an engine and a multi-mode transmission configured to transfer torque among the engine, first and second torque machines, and an output member. The input member includes a clutch element configured to prevent rotation of the engine in a first direction. In response to an output torque request when the engine is in an OFF state, the motor torques from the first and second torque machines are controlled in response to the output torque request including controlling the motor torque from the first torque machine at a positive torque greater than a minimum positive torque and controlling the motor torque from the second torque machine responsive to the output torque request and responsive to the motor torque from the first torque machine.