On the Effectiveness of Hybridization Paired with Eco-Driving

Eco-driving and hybridization both save fuel by reducing the energy loss during braking and using the engine efficiently. Considering this similarity, the hybridization requirements are different for the future connected and automated vehicles that can precisely optimize the vehicle velocity profile. This work investigates the necessary hybridization degree in an automated car following scenario. A novel hybrid system, called power split supercharger (PSS), is used in this study that is capable of working both as a parallel hybrid and a boosting device. The fuel minimization problem is divided into two independent optimizations, one for the velocity profile and the other for the energy management of the PSS. Dynamic programming is used to solve both problems. Different motor sizes are considered for the PSS system and the resulting fuel economies are compared to a turbocharged engine and a full hybrid electric (HEV) powertrain. The results show that the PSS system can provide 90% of the fuel economy gain achieved with a full HEV using a much smaller motor. For example, an optimized LA92 requires only an 18 kW motor or a 24 kW motor for the optimized US06 cycle as compared to the 60 kW motor for the full HEV.