Comparison of modulations and dc-link balance control strategies for a multibattery charger system based on a three-level dual-active-bridge power converter,

© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper focuses on the study of a charger for two batteries connected in series. From the three-phase grid, the batteries are charged through a three-level neutral-point-clamped (NPC) ac-dc converter in cascade with a three-level NPC dualactive-bridge converter. The system provides galvanic isolation and allows bidirectional power flow. A simple control strategy to charge the batteries is considered, based on the regulation of the common- and differential-mode components of the batteries charging currents. In addition, the proposed control system regulates the total dc-link voltage and the dc-link voltage balance in the two systems dc-links. This work is particularly focused on the comparison of the charger performance under two competitive ac-dc converter modulations, in terms of the ac-side voltage harmonic content, the number of switching transitions, the dc-link voltage balance, and the charging current control capacity. Simulation results with the performance comparison are provided and the merits and demerits of each option are highlighted.This publication is part of Grant DPI2017-89153-P, funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe.Peer ReviewedPostprint (author's final draft