Modeling and Analysis of Switched-Capacitor Equalizer Based on Shared Star-Structured Capacitor Network for Series-Parallel Battery Pack

To address the energy balancing issue of series-parallel battery packs, a novel switched-capacitor equalizer is proposed. The proposed equalizer achieves voltage equalization both within and between battery strings through the shared star-structured capacitor network. As a result, the number of capacitors required by the proposed equalizer is significantly reduced, leading to lower cost and smaller size. Additionally, the proposed equalizer can reduce the peak circulating current between battery strings and accelerate its decay. The topology configuration, control strategy, and working principle of the proposed equalizer are introduced in detail. The limit impedance of the proposed equalizer over the full frequency range is derived, providing theoretical guidance for parameter design and performance optimization. An experimental prototype of the proposed equalizer applied to a battery pack with two battery strings has been built. Experimental results confirm the effectiveness of the proposed equalizer, with a balancing efficiency of 94.75%.