Supercapacitor and Bidirectional DC-DC Converter-based Active Charge Balancing Scheme for Lithium-ion Batteries

The stored charge inside the series-connected lithium-ion battery cells within a battery pack must need to be well equalized for optimum capacity utilization, operational safety, and a longer lifecycle. This paper proposed an innovative supercapacitor and bidirectional DC-DC converter-based cell-to-pack-to-cell (C2P2C) active charge balancing scheme where a supercapacitor is used as a temporary energy tank while shuttling the balancing energy. The bidirectional DC-DC converter works in buck/boost mode to control the charging/discharging of the supercapacitor alongside modulating the balancing parameters to accomplish cell-pack and pack-cell balancing simultaneously during the charging and discharging period respectively. Laboratory test data is used for battery modeling and simulation studies are conducted in MATLAB-Simscape to verify the effectiveness of the proposed scheme. The most innovative and attractive aspects of the proposed scheme are its high balancing speed, reduced component requirement, and robustness compared to similar topologies in its class. A comparative study with state-of-the-art coupled inductor-based topology is also demonstrated to support the claim.