Optimal cost-emission trade-off for plug-in hybrid electric vehicles around zero emission zones using a supervisory energy and emissions management strategy

Abstract

The growing call for pollution-free environments has prompted the creation of zero-emission zones (ZEZs) around the world. For regional and national transport, plug-in hybrid electric vehicle (PHEV) are an attractive option, which also offer ZE driving. To address the PHEV challenges of sufficient ZE driving range and of meeting real-world emission targets outside the ZEZs, this work proposes an adaptive supervisory control strategy, which minimizes the total operational costs while complying with tailpipe $\mathrm{N}{\mathrm{O}}_{\mathrm{x}}$ emissions constraints. It combines a Modular Energy Management Strategy (MEMS), for cost-optimal power-split, with an Integrated Emission Management (IEM) strategy for determining the cost-optimal air path setting of the internal combustion engine. A real-time implementable, optimal control strategy is derived based on Pontryagin’s Minimum Principle. To determine the optimal selection of the co-states used in this strategy, a numerical optimization is performed for different route segments and real-world cycles. This study demonstrates that PHEVs can successfully be operated around ZEZs. The best performance is realized with an adaptive supervisory control strategy with different co-states per route segment; compared to the standard strategy with fixed co-states, this proposed strategy was able to achieve cost and $\mathrm{N}{\mathrm{O}}_{\mathrm{x}}$ emission reductions of up to 10% and 22%, respectively, for the studied real-world cycles.