Abstract: In this paper, the selection of battery capacity and a coordinated optimization on energy management strategy are conducted for a plugin hybrid electric bus (PHEB) with minimizing the overall cost (consisting of battery purchase cost and energy consumption cost during operation) as objective. Firstly a biloop optimizing procedure is devised, in which the outer loop is for choosing battery with different capacities while the inner loop performs the energy management strategy based on Pontryagins minimum principle (PMP) with the battery pack chosen. Then a simulation is conducted based on Chinese typical urban citybus driving cycle and the results show that the optimal battery pack capacity of PHEB is affected by multiple factors including the required driving range and the unitprice of battery etc. Finally, with the battery pack chosen, a comparative simulation on energy management is carried out with strategies of PMP, dynamic programming, chargedepleting / chargingsustaining and equivalent energy consumption minimization strategy respectively, and the energy consumption characteristics of four strategies are obtained.

Key words: plug in hybrid electric bus, battery capacity, energy management strategy, coordinated optimization, Pontryagins minimum principle, dynamic programming