Fast Battery Cell Voltage Equalizer Based on the Bidirectional Flyback Converter

Abstract

The prevalence of electromobility requires reliable battery energy storage systems that can assure the high demands for extended driving range of electric vehicles. To meet this demand, the battery management system (BMS) plays a major role. The requirements for the BMS vary according to the specific needs for each application. In this article, a high-equalization current BMS with high efficiency is implemented based on the bidirectional flyback converter. The modeling of the converter considering nonideal elements is combined with the genetic algorithm to select the parameters of the converter that maximize the efficiency of the BMS. As a result, a BMS for high-capacity lithium cells is implemented, achieving a 91.73% efficiency for a balancing current of 5 A and a peak efficiency of 94.19% for a balancing current of 2 A. The proposed BMS follows the bidirectional module-to-cell configuration and is intended for integration on independent cells. As a result, a smart cell is developed, which can be used in second-life battery applications.