Study On EV Hybrid Enengy Storage System And Its Control Strategy

On the growing problem of the environment pollution and energy crisis, electricvehicle（EV）has became an important developing direction for the future new energyvehicles because of its advantages of high efficiency, low nosie and zero emission.However, as a key component of EV, the low specific power and harmful impact onlifetime under large current of the battery are seriously affecting the dynamicperformance, sustaining range and use-cost of EV. Considering the high specificpower and the long cycling lifetime of the super capacitors., this paper studied on ahybrid energy storage system(HESS) by combining the battery as a primary energyand the super capacitors as an auxiliary energy to improve the performance of vehiclepower system.Firstly, the experimental analysis was carried out in view of the performance ofthe key components of HESS, i.e., lithium ion battery, super capacitor, and DC/DCconverter. According to the characteristics of different components, a scheme todetermine the structure topology and parameters matching of those key componentsare presented. By using the Matlab/simulink software， the function of the currentregulation control via DC/DC converter and the function of power splitting feasibilityof HESS are verified through simulation.After that, two control strategies for HESS are designed, i.e., the logic thresholdcontrol strategy and the model predictive control strategy are brought forward. Thecontrol effects of two control strategies have been analyzed and compared by usingMatlab/simulink. The simulation results between two control strategies are compared,and are illustrated that both of them are able to satisfy the power demand of HESS.Furthermore, the model predictive control strategy exhibits better smoothperformance of battery than the logic threshold control strategy.Finally, a prototype of HESS is set up, and the feasibility of power splitting ofHESS is verified. A contrast experiment between single battery system and HESS iscarried out, the comparing results indicate that the variation range of voltage andcurrent of battery in HESS is significantly reduced in contrast to the single batterysystem. Based on the above studies, the super capacitor had a prominent impact onsmoothing performance of the battery within HESS. It is benefit to extend the batterycycling lifetime and improve system efficiency, as well as proves the feasibility andsuperiority of HESS.