Equivalent Circuit Model of Supercapacitor for Self- Discharge Analysis - A Comparative Study

Self-discharge of supercapacitor is an important phenomenon that needs to be considered carefully, especially for the applications like wireless sensor networks, memory backup systems, etc. Different types of models have been proposed by the various researchers to capture the supercapacitor dynamics. In this paper, two electrical equivalent circuit models, variable leakage resistance (VLR) model and charge redistribution based model, have been considered for comparative study. Both the models have been analyzed based on the charge and long term self-discharge responses obtained through experimentation and simulation. The device under test is the Maxwell BCAP0100 P270 T07 supercapacitor. First, it has been charged at 2A constant current to its rated voltage; then, has been left for self-discharge. The terminal voltage has been collected for total charging time as well as self-discharge for 8000 seconds. The data have been acquired using National Instruments (NI) hardware and LabVIEW software. Based on the case study used in this paper, it is observed that the charge redistribution based model is better able to capture the self-discharge phenomenon. However, the error in the VLR model may not be insignificant always.