Optimal Selection of Driving Modes along a Commuter Route for a Plug-in Hybrid Electric Vehicle

Paper in proceeding, 2014

Many plug-in hybrid electric vehicles have predefined driving modes, e.g. electric drive and charge sustaining mode. For a driver it is not a trivial task to select a fuel optimal sequence of driving modes; a poor selection might even result in a severely degraded fuel economy. The purpose of this paper is therefore to investigate optimal mode selection along a well known commuter route. To obtain a predictable driving behaviour it is assumed that the driving mode is only allowed to change at a limited number of decision points, located where the driving conditions along the route changes. The optimal mode selection is computed using the well known Dynamic Programming algorithm. However, the results show that the optimal mode selection might be perceived as counterintuitive, as a mode is not necessarily optimal over a connected set with respect to battery state of charge, at a given decision point. To mitigate this type of behaviour a suboptimal algorithm is proposed, in which a mode is associated with one unique interval of state of charge at any decision point along the route. The results indicate that the proposed algorithm is only marginally suboptimal with respect to the optimal solution.