High-Speed Chain-Structured Cell Balancing Circuit for Low Earth Orbit Satellites

As the complexity of satellite missions grows, their overall power demands continue to increase. Consequently, efficiently managing Li-ion batteries through a battery management system has become crucial. In particular, achieving a high cell balancing speed is critical because low-Earth-orbit satellites must complete both battery charging and cell balancing within a limited Sun period. However, as the number of battery cells increases, conventional balancing methods exhibit various limitations, such as the requirement of a large number of components and low balancing speed between distant cells. Therefore, this paper proposes a cell balancing circuit to achieve a high cell balancing speed with fewer components. The proposed circuit employs a chain structure by adopting a coupled inductor into a conventional buck-boost Cuk (BBC) circuit. As a result, it has a small number of components with the inherent simple structure of the BBC circuit and enables fast balancing between distant cells. In addition, the proposed circuit achieves additional reduction of components with an integration of cell balancing modules. The practicality and effectiveness of the proposed circuit were demonstrated through experimental comparisons with an eight-cell Li-ion battery string.