Optimal Energy Management for Fuel and Emissions Minimization of Series Hybrid Electric Vehicles with Consideration of Engine Preheating

As a result of multiple energy sources, hybrid electric vehicles (HEVs) provide additional flexibility of the engine operating point, which enables optimization of fuel economy and emissions reduction. This paper introduces an energy management (EM) control strategy by an optimal control approach that jointly optimizes fuel consumption and various vehicle pollutant emissions. Engine thermal dynamics are modeled and integrated into the engine-out emission and fuel consumption models for enhanced modeling accuracy. The proposed method is formulated as an optimal control problem (OCP) that is benchmarked against a baseline EM strategy for fuel consumption only optimization. The proposed temperature sensitive emission and fuel consumption models enable a thorough investigation of engine temperature-emissions relationships, which provide important insights into the optimal power split during the engine preheating phase. Simulation results validate the effectiveness of the proposed approach and highlight the importance of analyzing the fuel consumption-emissions trade-off, as small compromises in fuel consumption lead to significant reductions in emissions.