Effect of Packaging on Supercapacitors Strings Modeling: Proposal of Functional Unit Defined Around Balancing Circuit

Supercapacitors (SCs), also called electric double-layer capacitors or ultracapacitors, nowadays have a considerable applicability as fast energy storage systems. Mostly, because of its low rated voltage, they are connected in series to reach the required voltage. The most usual approach for SC strings modeling is either the simplification of the whole string to an equivalent RC network, or the concatenation of individual models. However, these approaches lose accuracy because of electrical unbalances between cells. This paper proposes a new modeling approach that defines a new grouping strategy to improve the modeling of an SC string. It implies defining the string modeling around the combination of SCs and voltage balancing circuits. The resulting model is capable of reproducing the dynamic performance of an SC string with better accuracy. Experimental validation corroborates the improved dynamic response of the proposed modeling unit.