It has been shown that none of any energy sources which own high specific energy or high specific power, but not both, can solely fulfil all the demands of hybrid electric vehicle (HEV) in some circumstances. In this paper a battery/ultra-capacitor hybrid energy storage system (B/UC HESS) using ultracapacitors which replace primary sole Ni-MH energy source, without any changes in other parts of HEV was presented. Based on the energy flow of energy storage system and operating status of the vehicle, a nonlinear proportional factor control strategy with a goal of improving battery life was introduced. The simulation results under different urban driving cycles show that the peak charge/discharge currents are smoothed effectively, which benefits the battery lifetime improvement. The results also show that the buffering effect of ultracapacitors has optimized the charging and discharging processes of Ni-MH battery considerably.
FreedomCAR :electrical energy storage system abuse test manual for electric and hybrid electric vehicle applications.
