State of Charge Management for Plug In Hybrid Vehicles With Uncertain Trip Information

Abstract

Efficient state of charge management of plugin hybrid electric vehicles (PHEVs) differs from their nonplugin counterparts through the utilization of a charge depleting (CD) mode of operation. Several studies have shown that a blended mode of CD holds fuel economy advantages over a CD and charge sustaining (CS) combination, however, these approaches assume knowledge of the total journey distance. Here, this assumption is relaxed and the state of charge trajectory was recalculated online using a weaker assumption that only a probability distribution accumulated over past trips is available. The importance of other contributing factors to the state of charge profile such as vehicle velocity and altitude is also assessed. Simulation results on a prototype plugin hybrid are presented with an adaptive equivalent consumption minimization strategy (ECMS) used by the powertrain management to track the proposed state of charge trajectory. The financial and environmental benefits of the proposed approach relative to other state of charge management strategies are then calculated over a number of different cycles and conditions.