Distributed estimation of state-of-charge of supercapacitor packs: A consensus-based approach

It is crucial to estimate the state-of-charge (SoC) of a supercapacitor pack as cells are typically connected to form packs in practical applications. However, most of the existing studies adopted a centralized approach, which is to estimate all the single cells, and then calculate the overall SoC. When the total number of the cells comes to a high level, the burden of communication and the price of a single fault rise rapidly. To address this challenge, in this article, we propose a decentralized method for estimation of pack SoC, which is free of the central observer. We use the state space equation to model the supercapacitors in the physical modeling. In the cyber modeling, we construct their communication topology and apply a definition of pack SoC. A two-layer structure is proposed in which we design a Luenberger observer for each cell to estimate SoC of each cell. We propose a consensus-based algorithm to estimate its pack SoC. A laboratory testbed has been built to verify the effectiveness of the proposed method. Experimental results show that the proposed method can effectively implement the estimation and is more robust to communication failure than the centralized method. •We construct a cyber–physical system to estimate SoC for supercapacitor packs.•We propose a decentralized method based on dynamic consensus algorithm.•Decentralized method is robust to communication failure.•Decentralized method is practical and scalable.