The on-board or off-board energy storage system (ESS) plays a vital role in determining the performance at all electric range of the electric vehicles and in microgrid energy management. Most of the electric vehicles and micro grid nowadays use lithium-ion rechargeable batteries due to their high energy density and design flexibility and some unique electrochemical properties exhibited by lithium. To increase the range of the vehicle by 15% and increase the energy penetration to meet the peak load in microgrid applications, the incremental cost of ESS almost doubles. For effective operation of electric vehicle and microgrid energy management, the ESS should have high energy density and high-power density which is not available in any single energy source. Batteries generally have higher energy density but low power density and life cycle. Also, battery efficiency reduces if the load draws very high current in case of peak demands, and it might lead to thermal stress in the battery. Here comes the importance of supercapacitor, which has higher power density, life cycles and efficiency and a fast response on charge/discharge cycles when drawing high currents but has lower energy density. So, both the energy storage device complements each other in terms of energy density, life cycle and power density. Batteries with higher capacity can be used for higher power densities, but it is not a commercially viable solution. It also increases the weight, size and cost of the system. That is not a desirable option for automotive and microgrid applications to have constraints on size and weight. To get the advantages of both the energy sources, we need to develop a Hybrid Energy Storage System (HESS) to control the energy flow to the electric vehicle. In a HESS, therefore supercapacitor is used to supply higher power for acceleration and dynamic peak load variation to be met and absorb power during braking and excess renewable energy penetration, relieving the stress on Li-ion batteries and enhancing the battery life with optimal sizing addressing the economic analysis.
Department of Electrical and Electronics Engineering, School of Engineering, Coimbatore
Above 80% in M.Sc., chemistry
Associate Professor