Parametric Modeling of Components for Selection and Specification of Hybrid Vehicle Drivetrains

Drivetrain hybridization implies adding a secondary power source (electric machine/battery) to a primary power source (engine/filled fuel tank) in order to improve: fuel economy, emissions, drivability (performance), comfort and safety. Designing a hybrid vehicle drivetrain fulfilling the required vehicle driving functions is therefore a complex task. Many researchers have put effort formulating and developing overall hybrid drivetrain analysis, design and optimization models including top-level vehicle control strategy for optimal fuel economy. This paper seeks to investigate the possibility of overall model simplification for the hybrid drivetrain system including the control strategy. This is performed by describing the component efficiencies and control rules with only a few characteristic parameters that capture the total systems fuel efficiency with sufficient accuracy (~1%). Using these parameters the modeling and simulation process can be done very quickly. The method has been demonstrated on a series -, a parallel - and a series-parallel hybrid drivetrain with specified component technologies, vehicle parameters and drive cycle. The fuel economy and control strategy results are compared with Simulink/Advisor and Dynamic Programming.