A Decentralized SOC Balancing Method for Cascaded-type Energy Storage System

As unbalance state of charge (SOC) of storage units usually leads to the decrease of lifetime, SOC balancing control is essential. In this article, a decentralized SOC balancing method is proposed to balance the SOC of cascaded-type energy storage systems. Since the method does not rely on any communication, it possesses higher reliability. As is well known, SOC is a slowly changing variable compared to other variables such as voltage and current. Thus, the studied system has obvious two-time-scale characteristic. In addition, the stability analysis of the system based on the singular perturbation theory is carried out. Simulation and experiments are performed to verify the validity of the proposed SOC balancing scheme.