Analyzing a Resonant Switched-Capacitor Converter for Improving Lithium-Ion Battery Cells Balancing Speed

Active techniques based on the switched-capacitor converters (SCCs) are used in recent years widely for battery cell balancing applications, due to lack of bulky magnetic components. In addition, these converters are easily be integrated to reduce the volume. Despite of all these benefits, SCCs have some disadvantages such as number of active switches, currents spikes, low balancing speed, and high switching losses. In this paper, a chain resonant SCC is analyzed which can realize soft switching under the ZCS conditions to eliminate currents spikes to overcome the aforementioned SCCs drawbacks. Also, it has been modified to increase balancing speed of the Lithium-Ion battery cells. Then, a chain resonant SCC for balancing a combination of three battery cells with capacity of 2150 mAh and nominal voltage of 3.6 V has been simulated by MATLAB/SIMULINK and it has been implemented at 50 kHz to confirm operation of the converter. The simulation and experimental results are in good agreement with the given mathematical analyses and illustrate that the balancing speed has been improved more than three-fold, as compared with the conventional converter.