Study on ultracapacitor-battery hybrid power system for PHEV Applications

For the battery only power system is hard to meet the energy and power requirements reasonably, a hybrid power system with ultracapacitor and battery is studied. A Topology structure is analyzed that the ultracapacitor system is connected with battery pack parallel after a bidirectional DC/DC converter. The ultracapacitor, battery and the hybrid power system are modeled. For the plug-in hybrid electric vehicle (PHEV) application, the control target and control strategy of the hybrid power system are put forward. From the simulation results based on the Chinese urban driving cycle, the hybrid power system could meet the peak power requirements reasonably while the battery pack's current is controlled in a reasonable limit which will be helpful to optimize the battery pack's working conditions to get long cycling life and high efficiency.