Plug-in hybrid electric vehicles (PHEVs) have generated significant interest for their potential to decrease dependence on imported oil and to cut pollution and greenhouse gas emissions. While hybrid electric vehicles (HEVs) rely on their internal combustion engines to recharge their batteries, PHEVs generally have larger batteries and can be recharged by plugging into an outside electricity source, such as a standard home outlet (Figure 1). As a result, PHEVs are potentially more efficient and cleaner than HEVs, in part because more of their energy can come from clean, renewable sources.
A critical consideration in PHEV development is how energy is produced and used. More flexible and intelligent PHEV energy management strategies can save energy and produce lower emissions. This can translate to an increase in fuel economy of 5 to 10 more miles per gallon of gas for a typical PHEV that already gets 60 miles per gallon. We discuss one strategy to optimize energy management by accounting for vehicle position, speed and acceleration, trip progress, roadway characteristics, traffic conditions, and battery recharging opportunities at intermediate stops. We then evaluate this energy management strategy using an example trip, and find that it can result in substantial efficiency gains.