A new cell-to-cell balancing circuit with a center-cell concentration structure for series-connected batteries

A bidirectional cell-to-cell balancing structure using two switches per each cell shows good balancing ability, but many switches lead to increase of the cost and size. To reduce the number of switches, this paper proposes a new cell-to-cell balancing circuit with a center-cell concentration structure. The proposed circuit collects the charges of the overcharged cell into the center-cell, and then the collected charges are redistributed to the other cells. The proposed circuit has unidirectional balancing structure with single switch per each cell, but it can achieve competitive balancing ability compared to bidirectional structure. In this paper, the operational principles of the proposed circuit are analyzed, and the comparison between the proposed and conventional circuits is shown. To verify the validity of the proposed circuit, experiment with 8 batteries is carried out, and the experimental results show the improved cell balancing ability although one switch is used per each cell.