A novel fast charging technique using supercapacitors

Electric vehicles today are considered to be one of the most promising modes of sustainable transport. However, the major deterrent to their mass penetration is the long charging time. This paper proposes an alternative technique to reduce the effective charging time, involving lithium ion battery and a supercapacitor bank. The lithium ion battery is charged to 60% of its capacity, and the supercapacitor is sized to contain the energy contained in the remaining 40% of battery capacity. The combination is charged at a predetermined value of current, in the presence of a battery protection circuit and supercapacitor balancing circuit. The total charging time was found to be less than 40 minutes. A scaled down model of an electric vehicle was also built, with an effective battery management system, which allows switching between the battery and capacitor for its different modes of operation and effective tackling of terrain. This is expected to be especially useful for electric taxis, in the urban landscape.