A generic transmission model for hybrid electric drives

The design problem of hybrid electric drivetrains has a large design space, especially, when complex dedicated hybrid transmissions that combine an internal combustion engine with multiple electric machines are considered. To evaluate a drivetrain design over a driving cycle, a transmission model is needed. To avoid the need of modeling every drivetrain concept individually, a generic transmission model for hybrid electric drives is developed. The developed model integrates the dynamic behavior of all conventional-, electric-, and hybrid- transmission mode types. Mode types and mode type dependent control variables are defined. The outputs of the model are the torque and rotational speed of all power sources of the drivetrain. The inputs of the model are the torque and speed of the wheels, and the control variables. As a practical example, the model is used to compare the energy efficiency of two complex dedicated hybrid transmissions by optimizing the control for both over a driving cycle.