The Switched-Capacitor Voltage Equalizer of Battery Strings: A Hybridized Capacitors Approach for High Balance Speed

Abstract

Traditional switched-capacitor (SC) balancing systems are favored for the structural simplicity but are limited by slow balancing speed. To address these drawbacks, a hybridized switched-capacitor equalizer is proposed. By incorporating hybrid series–parallel capacitors under both series and parallel configurations, the proposed structure significantly enhances balancing speed. A parallel capacitor enables energy equalization between adjacent modules, whereas the series capacitor allows for power exchange among arbitrary cells throughout the battery pack. The equalization rate is significantly accelerated by establishing multiple channels for power flow. Meanwhile, the proposed balancing topology eliminates one capacitor, reducing system cost and volume. Owing to the series–parallel characteristics of capacitors, removing one capacitor also enhances the overall energy transfer rate. To empirically validate the proposed architecture, an experimental test bench comprising five series-connected battery cells was established. Measured data indicate that the system achieves effective equalization under charging, discharging, and idle conditions.