An active direct cell-to-cell balancing circuit in continuous current mode for series connected batteries

Bi-directional cell-to-cell balancing circuits can well prevent voltage imbalance of batteries that are connected in series. However, it is a challenge to achieve high equalization speed and equalization efficiency with low complex circuit structure. In order to overcome this challenge, it is proposed that a direct bi-directional cell-to-cell active equalization method that works in continuous current mode (CCM) is used. The proposed balancing circuit allows energy to transfer directly from the source cell to the target cell in one step, which guarantees high balancing speed and efficiency. The experiments in which six-20 Ah lithium-ion batteries are connected in series have been carried out, and the results show that the balancing circuit achieves a good comprehensive performance of equalization in efficiency, speed, and circuit complexity.