Fuel consumption optimization for a plug-in hybrid electric bus during the vehicle-following scenario*

In this paper, a robust SOC (state of charge of battery) trajectory planning method is proposed for a plug-in hybrid electric bus (PHEB) in the vehicle-following scenario. Firstly, the trajectory areas of SOC are planned based on the Taguchi robust design (TRD) considering the noises of the vehicle mass and driving cycles. Moreover, the reliability of the result of TRD is verified based on the Monte Carlo simulation (MCS). Then, the longitudinal driving control of PHEB is transformed into a multi-objective optimal problem that incorporates driving safety, fuel economy and ride comfort in the vehicle-following scenario. Finally, based on a novel nonlinear model predictive control (NMPC), the electric motor, engine and brake system are collaboratively optimized to comprehensively adjust the dynamic and economy of PHEB. The results show that the planning trajectory areas of SOC effectively improved the fuel economy compared with the pre-planning. Furthermore, based on the novel NMPC, the fuel consumption of the proposed method is lower than the method that just adds an energy management strategy to adaptive cruise control (ACC + EMS). The hardware-in-loop test results show that the proposed method can be implemented into the vehicle controller, and the results between the HIL and offline simulations are largely coincident.