Compensation of dynamic torques and flywheel start in a CVT based hybrid Powertrain

At the Technical University Munich a new powertrain for cars, that enables a maximum of energy saving and drivability at low complexity is under development in cooperation with the companies Epcos AG, GM Powertrain Europe, ZF Friedrichshafen AG and ZF Sachs AG. It mainly consists of a mild-hybrid structure and a wide spread CVT gearbox. To improve driveability the start of the internal combustion engine is performed using the flywheel effect of decelerated moment of inertia of the electric motor. Starting from the engery saving potentials this paper describes the structure and control of the powertrain. Furthermore the limits of dynamics of the CVT due to hydraulic operation are discussed and resulting operating method to apply the desired torque on the output, is described. In doing so the focus is on balancing torques and providing angular momentum for the start of the internal combustion engine.