J. Soldo, B. Škugor, J. Deur

Analysis of Patterns of Optimal Battery State-of-Charge Trajectories for Blended Regime of a Parallel Plug-in Hybrid Electric Vehicle and a Wide Range of Driving Conditions

15th Conference on Sustainable Development of Energy, Water and Environment Systems (SDEWES), Cologne, Germany, 2020.
Plug-in hybrid electric vehicles (PHEVs) typically combine several power sources, which introduces a need for optimal energy management strategy design. When considering the so-called blended mode in which the engine is regularly used over a trip, the shape of battery state-of-charge (SoC) trajectory over travelled distance is of particular importance to achieving optimal powertrain operation. This paper deals with in-depth analysis of optimal SoC trajectories obtained by off-line control variable optimisation of a PHEV-type city bus given in parallel (P2) powertrain configuration, where a dynamic programming (DP)-based optimisation algorithm is used for a wide range of driving cycles and scenarios. Along with previously found and comprehensively analysed linear-like trend of SoC trajectory over travelled distance occurring typically for zero road grade cases, this paper puts special emphasis on explaining SoC trajectories deviating significantly from the linear trend, which occur in the case of non-zero road grade profiles or driving cycle with relatively longer distance.