Design and Analysis of a Bridge‐Structured Switched‐Capacitor Voltage Equalizer for Series‐Connected Battery String

ABSTRACT Switched‐capacitor‐based cell voltage equalizers have gained considerable attention in recent years for battery management system (BMS) design due to their simple control strategy and ease of implementation. However, the balancing speed and efficiency of existing switched‐capacitor equalizers (SCEs) remain unsatisfactory for large battery strings. To address these limitations, a bridge‐structured switched‐capacitor equalizer (BSSCE) is proposed to enhance both balancing speed and efficiency across various cell voltage distributions. The proposed BSSCE enables simultaneous energy transfer among multiple cells through multiple optimal balancing paths, thereby minimizing the effective resistance under both slow‐ and fast‐switching limits. This feature allows the equalizer to draw higher balancing currents and enhance the overall balancing speed. An experimental prototype using four series‐connected battery cells has been developed to validate the effectiveness of the proposed design. Both experimental results and effective resistance analysis confirm that the proposed BSSCE achieves automatic any‐cell‐to‐any‐cell (AC2AC) and adjacent‐cell‐to‐cell (AC2C) equalization, depending on the switching frequency. The equalizer demonstrates a high balancing speed and achieves a peak balancing efficiency of 94.01%, confirming its effectiveness for high‐performance energy management applications.