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 the electric vehicles. To meet this demand, the Battery Management System (BMS) plays a major role. The requirements for the BMS variate according to the specific needs for each application. In this paper, a high-equalisation current BMS with high efficiency is implemented, based on the bi-directional flyback converter. The modelling of the converter considering non-ideal elements is combined with the Genetic Algorithm to select the parameters of the converter that maximise 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 bi-directional module-to-cell configuration and is intended for integration on independent cells. As a result, a smart cell is developed that can be used in second-life battery applications.