Power Management Strategy for Plug-in Hybrid Electric Vehicles using Engine Switching Status

Plug-in hybrid electric vehicle (PHEVs) is a kind of hybrid electric vehicles (HEV) that has a large capacity battery to satisfy the requirement of the distance for commuters. A parallel PHEV has two kinds of power source, internal combustion engine (ICE) and electric motor (EM), so that a control strategy to split the driving power to ICE and EM is important to have a superior fuel economy. In this paper, we propose a rule-based and an optimization-based strategies to guarantee fuel consumption and vehicle performance by deciding engine on/off status. For the developed rule-based method, a proportional algorithm is developed with the information of trip distance to generate a dynamic threshold which decides when to turn the engine on. If the engine is turned on, it is operated at the best efficiency with the desired of vehicle speed. Subsequently, an optimization-based method by using model predictive control (MPC) is addressed for PHEVs with guaranteed battery trajectory while minimizing fuel consumption. Both the control strategies can improve fuel economy comparing with other strategies, and the proposed methods are considered and studied via numerical simulations.