A New Control Strategy of Hybrid Battery/Ultra-capacitor Energy Storage in Electric Vehicle

Due to simple implement of exchanging battery at a short time and development of quick-charging technology, the problems encountered in electric vehicle developing has been got a new adjustment, that is to say, which gradually returned to dynamic response speed of power system and energy efficiency improvement. The battery/ultra-capacitor units of hybrid energy storage system are connected to DC link with buck/boost bi-directional DC/DC converter in this paper, battery as a main power unit adopts the current control mode, ultra-capacitor as an auxiliary unit with composite double closed-loop control ensures the power balance in this system. Small signal model of the energy storage system is established, and battery charging/discharging current controller is designed, ultra-capacitor energy storage unit improve the dynamic response speed of the electric vehicle by compound double closed loop control with a load current feed-forward, power sharing between the units can be well realized by secondary battery charging/discharging current adjustment and the ultra-capacitor control function.