A bidirectional converter with integrated voltage equalizer for series‐connected supercapacitors. (9th January 2022)

• Record Type: Journal Article
• Authors: Yang, Xiaoguang; Jia, Zhe; Wang, Dexin; Zhao, Xiaobing; Su, Yukui; Nie, Baoxin
• Is Part Of: International journal of circuit theory and applications. Volume 50:Number 4(2022)
• Page Start: 1174
• Page End: 1193
• Publication Date: 2022-01-09
• Subjects: bidirectional converter -- supercapacitors (SCs) -- voltage equalizer -- voltage multiplier; Electric circuit analysis -- Periodicals; 621.319205
• DOI: 10.1002/cta.3221
• Languages: English
• ISSNs: 0098-9886

Abstract

Summary: Energy storage systems include not only a charge/discharge bidirectional converter but also a separate voltage equalizer. This paper proposes a bidirectional converter with an integrated voltage equalizer, which saves a DC–AC converter, thus significantly reducing the size, cost, and complexity of the equalization circuit. In addition, integrating the equalizer into the bidirectional converter also has a positive impact on the realization of ZVS operation. Analytical models have been established that can be used for accurate prediction, optimal design, and effective control of the proposed converter. A control strategy is proposed, which not only enables the cells to be automatically balanced when the cell string is charged/discharged but also enables ZVS operation within a wide range of voltage changes and minimizes the RMS value of the primary current. An experimental prototype of 60 W applied to nine supercapacitors (SCs) in series was built, and the experimental results verified the theoretical analysis and demonstrated the characteristics of the proposed converter. Abstract : This paper proposes a bidirectional converter with an integrated voltage equalizer to simplify the system. The proposed integrated converter saves a DC–AC converter, which is necessary for conventional string‐to‐cell equalizers. Integrating the equalizer into the bidirectional converter also has a positive impact on the realization of ZVS operation. The proposed converter can automatically balance the cells while charging/discharging the string over a wide output voltage range.