Modeling and Sizing of Supercapacitor Pack for Electric Vehicle Applications

Supercapacitor is one among the most promising energy storage technology for electric vehicle applications due to their long cycle life, fast charging and discharging rates and high power density. supercapacitor is used as an auxiliary energy storage in order to provide a peak power during acceleration mode and also provide an energy recovery during regenerative mode. To determine the characteristics of supercapacitor during charging and discharging process an accurate model is essential. Several cell level modeling approaches are described for supercapacitors and the most commonly used are Stern-Tafel, Thevenin, Zubieta and Series model. The main objective of this modelling approaches is to choose the best model that can represent the exact behavior of supercapacitor. For the aforementioned reason, a performance comparison is made to check the voltage accuracy of these models by providing various current profiles as an input. From the analysis, a series model is chosen as base model for building the supercapacitor pack and it provides an accurate estimation of pack voltage. Further this approach is helpful in sizing the supercapacitor pack from cell level based on the maximum speed of the driving cycle.