A Study on Active Balancing Methods by Battery Stack Power Recovery

Recently, the demand for energy storage has increased, serial cell configurations are commonly used for high-capacity secondary batteries. Initially, when identical cells are configured in series, the battery cells operate without voltage differences. However, over time, voltage imbalances occur due to differences in the environmental and physical properties of the cells. In addition, the unique characteristics of cells change during charging and discharging, which greatly affects to the degradation of battery efficiency and performance. Various cell balancing techniques have been proposed to achieve high efficiency and performance in battery. This paper proposes a minimum voltage selective balancing topology based on a flyback converter for module balancing of batteries based on active cell balancing techniques. In the proposed topology, the output voltage of each battery is shared through a single transformer, the energy from the converter's primary side is transferred to the battery modules with the minimum voltage. The proposed module balancing circuit can be easily applied to the battery reuse industry. The proposed minimum voltage battery module selective balancing topology was verified through PSIM simulations and experiments.