A thermal model-based engine on-off control in HEVs

An Internal Combustion Engine (ICE) experiences increased friction loss and fuel injection in cold temperatures, which provides the potential to further improve the energy efficiency based on the control freedom in hybrid electric vehicles (HEVs). This paper presents an engine thermal model with the coefficients calibrated through bench tests under different engine operating points. Moreover, we propose an engine on/off strategy that considers both the power demand and engine temperature preservation. Simulation results verify that the proposed powertrain control with engine thermal dynamics can further improve the energy efficiency for HEVs.