A multi‐module equalization system for lithium‐ion battery packs

Abstract

Battery inconsistency in electric vehicles is an important factor causing battery capacity degradation and safety problems. Therefore, battery equalization technology plays an important role in improving the performance and safety of battery packs. Among the existing equalization technologies, passive equalization is inefficient and active equalization is expensive and complex. Most of the active equalization algorithms only consider the balance of the cells within the battery module, but the balance between modules are not involved. However, battery packs for electric vehicles often consist of multiple modules, cooperative equalization between modules are essentially required to improve the balance efficiency. A novel cooperative equalization system for multi-modules in the battery pack is proposed in this paper. The system combines active and passive equalization, and also includes a fast discharge function for balancing modules by a power resistor. An equalization algorithm aiming at the optimal equalization time is studied. Finally, the equalization system is verified in simulation and experiment. The experimental results show that the proposed equalizer demonstrates good performance in different consistency cases using the proposed control strategy and optimization equalization algorithm.

Multi-Mode Lithium-Ion Battery Balancing Circuit Based on Forward Converter with Resonant Reset

“…At present, lithium-ion batteries are widely used in electric vehicles (EVs), aerospace, and energy storage systems [1][2][3] because of their high energy density, high power density, lack of memory effect, low self-discharge, and long service life [4][5][6]. However, due to variations in manufacturing tolerances, operating temperatures, and aging levels, inevitable differences exist among cells in terms of electrical parameters such as internal resistance and capacity [7].…”