Synchronized Cell-Balancing Charging of Supercapacitors: A Consensus-Based Approach

Abstract

The switched resistor circuit has been a popular cell balancing scheme in low-power supercapacitor applications. However, the cell balancing performance of the circuit is vulnerable to current variations and resistance deviations with the existing asynchronous cell-balancing (ACB) method. To address this challenge, in this paper, we propose a synchronized cell-balancing (SCB) method based on the consensus theory, with the aim of synchronizing cell voltages during the charging process. First, the cyber-physical modeling of the cell balancing system is presented, where the physical layer models the circuit components and the cyber layer represents the communication topology among cells. Second, a distributed voltage tracker is proposed using a consensus tracking protocol, which benefits from a good scalability. A compensator is designed to stabilize the closed-loop multiple-in-multiple-out (MIMO) system and frequency-domain methods are applied to determine the compensator parameters. A laboratory testbed has been built to verify the effectiveness of the proposed method. Experiment results show that the SCB method has a better tolerance of current variations and resistance deviations than the ACB method.