A charging equalizer based on Zeta converter for hybrid energy storage system

Abstract This thesis proposes a charging equalizer for hybrid energy storage systems, incorporating the Zeta converter, voltage multiplier, and multi‐winding transformer. The objective is efficient charging and equalization for battery and supercapacitor strings. The Zeta converter serves to charge the battery string, while the transformer with multi‐winding shares the inductor of Zeta converter as the primary side, facilitating battery string balancing through the utilization of current ripple in the inductor. Additionally, the voltage ripple generated by the Zeta converter is utilized to drive the voltage multiplier, enabling the charging and equalization of the supercapacitor string. The system's operation halts upon reaching the predefined threshold voltage for the supercapacitor strings. The proposed circuit transforms into a Zeta converter by employing a single‐pole double‐throw switch, facilitating the charging of the battery strings. Experimental validation uses four series‐connected supercapacitors and four series‐connected batteries, demonstrating successful equalization and charging for both energy storage components.