Research on city-bus application-oriented real-time optimal energy management strategy for plug-in hybrid electric bus

With the gradual increase of the electric power ratio, the energy hybridization might be implemented in the electromechanical coupling system of plug-in hybrid electric vehicle. But for the complicated and transient driving conditions of city bus, how to minimize the energy consumption within the driving cycle through designing the real-time energy management strategy for plug-in hybrid electric bus(PHEB) might be the research focus in the academia. Considering the characteristics of the driving condition of city bus and the single-shaft parallel hybrid powertrain, an equivalent grade estimation method and the relevant battery state of charge(SOC) correction approach are proposed, and then based on the above two approaches, the energy in one city bus route might be optimally distributed by the employed equivalent consumption minimization strategy(ECMS). In addition, considering the frequently engine start-stop, the relevant rules are added into the ECMS to make the optimal solution more reasonable and improve the engine efficiency. Simulation results indicate that the proposed strategy might improve the fuel economy of PHEB and match the driving condition of city bus and the single-shaft parallel hybrid powertrain comparing with the rule-based strategy. So the proposed strategy might provide the theoretical basis for the application of optimal-based energy management strategy.