Abstract:

 A method of parameter optimization and energy management was proposed for a hybrid energy storage system (HESS) to prolong the life of lithium-ion batteries. The HESS parameters of a target hybrid electric vehicle (HEV) were optimized by using a dynamic programming algorithm based on a life model of lithium-ion batteries established by the authors under driving cycles to obtain the parameters of lithium-ion batteries and super-capacitors at the lowest cost. A fuzzy controller was designed to manage the energy of the HESS with input parameters of the vehicle speed, the vehicle power requirement, and the state of energy (SOE) of a super-capacitor. And a prototype was made for experimental verification. The results show that the battery lives are prolonged by 18.0%, 31.2% and 38.3% respectively under the regulations of the new Europe driving cycle (NEDC), the urban dynamometer driving schedule (UDDS) of USA, and the Economic Commission for Europe (ECE) of UN, and the cost per kilometer decreases by 17.2%.

Key words: hybrid electric vehicle (HEV) ,  hybrid energy storage system (HESS) ,  lithium-ion batteries ,  supercapacitors ,  battery life ,  energy management