Coupled velocity and energy management optimization of connected hybrid electric vehicles for maximum collective efficiency

The infrastructure for vehicle-to-everything has facilitated the development of intelligent eco-driving and energy management, exploring the energy-saving potential of connected hybrid electric vehicles (CHEVs). However, this approach, predominantly focused on individual performance and forward traffic flow, often sacrifices a holistic view. It tends to neglect the following vehicles and overlooks collective traffic efficiency, thus undermining the collective energy footprint. To address this, this paper proposes an efficient nested parallel optimization (NPO) strategy based on the ‘1+n’ mixed platoon concept. This strategy embeds Pontryagin's minimum principle into a constrained optimal control framework, which allows for simultaneous solutions to speed planning and energy management of CHEVs. It effectively reduces the dimensions of state and action space while considering traffic efficiency and fuel consumption across multiple intersections. Numerous verifications based on real driving scenarios demonstrate that the proposed NPO method can effectively tackle the coupled optimization problem, improving fuel economy by over 2.6% compared to sequential optimization. Moreover, under various traffic volumes, the proposed method outperforms conventional single vehicle-oriented optimization in terms of overall traffic energy economy and reduced travel time delays.