Fuel Economy Benefits of Electrified Powertrains with Advanced Combustion Engines: Mild to Strong HEV Applications

摘要

Powertrain electrification including hybridizing advanced combustion engines is a viable cost-effective solution to improve fuel economy of vehicles. This will provide opportunity for narrow-range high-efficiency combustion regimes to be able to operate and consequently improve vehicle's fuel conversion efficiency, compared to conventional hybrid electric vehicles. Low temperature combustion (LTC) engines offer the highest peak brake thermal efficiency reported in literature, but these engines have narrow operating range. In addition, LTC engines have ultra-low soot and NO_x emissions, compared to conventional compression ignition and spark ignition (SI) engines. In this study, advanced easily verifiable optimal control techniques are employed as the energy management supervisory controller to investigate hybridization of multi-mode LTC-SI engines for applications ranging from mild to strong hybrid electric vehicles (HEVs). A multi-mode LTC-SI engine is experimentally developed at Michigan Tech. University and the engine operating modes include homogeneous charge compression ignition (HCCI), reactivity controlled compression ignition (RCCI), and conventional SI. The powertrain controller is designed to enable switching among different modes, with minimum fuel penalty for transient engine operations. Moreover, the engine emissions are controlled by considering the catalytic convertor light-off temperature in the control framework for selecting the engine operating points. The developed multi-mode engine is analysed in series architecture and P2 parallel architecture in various hybridization levels.