Smart Cell Equalizer for Lithium-ion Battery Packs

摘要

The variations in the manufacturing process and non-uniform stress during usage makes the Li-ion cells in a battery pack to have difference in parameters such as internal resistance, cell capacity, self-discharge rate, etc. These variations aid the battery ageing process and limit the performance of the battery pack. To achieve higher performance and uniform ageing, a smart cell equalizer is proposed in this paper. Apart from the normal cell equalizer which causes further stress to the cells, this paper proposes a smart and dynamic cell equalizer using the forward converter to assist the individual cells in the battery pack. The equalizer tries to keep SoC levels of all cells near-equal levels by dynamically supporting each cell. The proposed method is validated using MATLAB/Simulink simulations. The results show that the proposed scheme is able to balance SoC in all dynamic conditions and module-level SoC balancing is also achieved without using additional circuits.