A tailored approach for the comprehensive design of a multimode power-split e-CVT powertrain for a full-hybrid electric vehicle

Abstract

The comprehensive design of a hybrid electric vehicle powertrain with a multimode power-split transmission is complicated by the driveline constructive complexity. The design approaches available in the literature are often based on mere explorative numerical methods mainly focused on the topological structure of the transmission without integrating the sizing of the engine or the electric unit. This paper aims to fill this literature gap by providing a tailored physical-based design procedure that, starting from a blank sheet and knowing only the vehicle parameters and desired performance, leads to the overall definition of the powertrain. The design approach is hierarchical, whereby each phase is decoupled from the others and the designer is made aware of cause-effect relationships at any design stage. Step by step, the power size of engine, battery, and electric machines is defined, and the functional and constructive arrangement of a multimode power-split transmission is synthesised, identifying the best operating range for input-, output-, and compound-split modes. The application on a C-segment full-hybrid electric car, which resulted in different but comparable solutions, proved the effectiveness of the method.