Coordinated control of a mechanical hybrid driveline with a continuously variable transmission

Requirements for a driveline with respect to fuel economy and driveability can generally not be met simultaneously even with a continuously variable transmission (CVT). A new driveline concept with an additional flywheel makes it possible to compensate for the engine inertia in transient situations. This allows the driveline to be operated for optimal fuel economy without losing driveability. However, to realize this objective it is inevitable to control the driveline in a coordinated way. In light of the system uncertainties and the unknown load as well as nonlinearities a nonlinear robust controller is proposed to generate the setpoints for engine torque and CVT ratio. The focus is on the control law for the CVT ratio setpoint. The controlled CVT regulates the power flow from the engine and flywheel to the wheels while compensating for the internal inertias.