A study of energy consumption in battery/super capacitor hybrid system based on optimized driving strategy

These days, hybrid electric vehicles have become main stream of car sale in the world. Several automobile companies have plan to change all kinds of vehicles of them as hybrid electric vehicle. Hybrid system can combine the strengths of both systems if the systems are well controlled. Typical hybrid electric vehicle has only one electric storage system, battery. But battery is based on electrochemical and life cycle can change depends on situation like DoD(Depth of Discharge), peak current. Although super-capacitor has high cost and low energy density, the strength of super-capacitor is ultimately high efficiency and extremely robustness from physical characteristic. So if super-capacitor helps the battery when peak current loads or frequent charge-discharge, the electric storage system accomplishes better efficiency and longer life cycle in spite of low energy density of super-capacitor. In this study, we use optimal control strategy 2 times to find potential value of supercharger in series hybrid vehicle. The study shows very high potential using only lower than 5 percent of the battery capacity. The loss of electric storage system decreases almost 40%. We can study more about price of super-capacitor and benefit of efficient operating electricity as further research.