Integrated Li-Ion Battery and Super Capacitor based Hybrid Energy Storage System for Electric Vehicles

In this paper, system integration and hybrid energy storage management algorithms for a hybrid electric vehicle (HEV) having multiple electrical power sources composed of Lithium-Ion battery bank and super capacitor (SC) bank are presented. Hybrid energy storage system (HESS), combines an optimal control algorithm with dynamic rule based design using a Li-ion battery and based on the State Of Charge (SOC) of the super-capacitor. Battery bank offers higher energy density while Super Capacitors possess better power density to meet dynamic performance of the drive. The bidirectional two-quadrant front-end dc-dc converter (BDC) is the key component to control the energy flow between the battery and the super-capacitor. Through proper control and setting of key parameters, good acceleration/deceleration, reversible driving, and braking characteristics are obtained. To overcome the degradation of life-cycle in battery due to continuous acceleration and de-acceleration caused by high current due to regenerative braking mode, Super Capacitors is used in proposed HESS. Thus, the proposed energy storage model offers good dynamic performance, well regulated output voltage and maximum braking energy capture. The MATLAB/Simulink model developed shows the behaviour of HESS based electric vehicle under charging and constant speed using a 12/48 V BDC.