| Lithium-ion batteries have been widely used among portable electronic devices, industrial machine tools, transportation services, aerospace, telecom industry, etc. In the battery energy storage system, the battery charger is a power converter used to charge the battery pack. The bi-directional DC/DC converter is used in most of these applications to provide load voltage regulation and reduce the cell count. In addition, the battery energy storage system needs a comprehensive battery management system (BMS) to work safely and effectively. As an important function of the BMS, the battery equalization is becoming more and more important for advanced battery systems because it can reduce the imbalance between battery cells and thus improve the system performance and lifetime.;In this dissertation we will give an introduction to the conventional centralized battery energy storage system. We will review the battery pack, battery charging, bi-directional DC/DC converter and the BMS with a special focus on battery equalization. The battery equalization technologies are reviewed based on various equalization methodologies and equalizer topologies. We will also introduce the work done in the distributed battery system. The rest part of the dissertation introduces, analyzes and discusses the proposed novel module-integrated distributed battery energy storage system. The system implementation, advantages and challenges, modelling and control, design considerations, simulation and experimental verifications, and other application opportunities are studied in this work. The proposed module-integrated distributed battery energy storage system is proved to provide satisfied functional performance regarding charging, discharging, equalization with additional advantages such as flexible and extendable configuration, high equalization efficiency and speed, full cell level protection, high integration and reduced size, enhanced protection and reliability, etc. |
