An Innovative Hybrid Energy Storage Device for Electric Vehicle

The widespread adoption of electric vehicles (EVs) demands on-board energy storage that simultaneously delivers high energy density for range, high power density for acceleration and regenerative braking, long cycle life, and competitive lifecycle cost [1]–[3], [7]. We present a hybrid energy storage device (HESD) that couples a lead-acid battery string with a super capacitor (SC) bank through a semi-active bidirectional DC/DC converter [5], [10]. Compared with a battery-only baseline, the proposed HESD improves peak power capability by 47 %, reduces battery current ripple by 68 %, and extends estimated battery life by 34 % under the UDDS urban drive cycle simulation [2], [6], [8]. A 10-year total cost of ownership (TCO) analysis shows a $975 net saving per vehicle, despite a $1 650 higher upfront investment, owing to fewer battery replacements and higher charging efficiency [6], [20]. Experimental results on a 1 kW laboratory prototype validate the control strategy and corroborate the simulation [4], [9].