An Intermodular Active Balancing Topology for Efficient Operation of High Voltage Battery Packs in Li-Ion Based Energy Storage Systems: Switched (Flying) DC/DC Converter

Abstract

To meet the load voltage and power requirements for various specific needs, a typical lithium–ion battery (LIB) pack consists of different parallel and series combinations of individual cells in modules, which can go as high as tens of series and parallel connections in each module, reaching hundreds and even thousands of cells at high voltage (HV) levels. The inhomogeneity among the cells and modules results in voltage imbalances during operation and reduces the overall system efficiency. In this work, a robust and flexible active balancing topology is presented. It can not only mitigate the charge imbalance within a module, i.e., intramodular equalization, but also help to balance the state of charge (SoC) level of the modules in a high voltage pack, i.e., intermodular equalization, which is an often-overlooked topic. The proposed concept was proven by experimental verification on parallel and series configurations of cells in realistically sized modules and practical battery management system (BMS) hardware, when the LIB was both idle and under load.

Powering the Future: A Comprehensive Review of Battery Energy Storage Systems

“…A reliable and adaptable active balancing topology is proposed in [47]. It can help to balance the state-of-charge level of the battery modules in a high-voltage pack, which is a frequently ignored subject, as well as the charge imbalance within a module, or intramodular equalization.…”

Average Model of Switched-Energy-Tank Battery Equalizer for Accelerated Performance Assessment

“…Active methods transfer energy from high-voltage cells to low-voltage cells via an energy tank. Such an energy tank can be a converter [17][18][19][20][21][22][23], an inductor in the switched-inductor equalizer (SI-E) [24][25][26], a capacitor in the switched-capacitor equalizer (SC-E) [27][28][29][30][31], or a resonance circuit in the switched-resonance equalizer (SR-E) [32][33][34]. Due to their high equalizing capabilities and efficiency, as well as the similarity of their operations, they can be referred to as switched-energy-tank equalizers (SET-Es).…”