Active balancing method for series battery pack based on flyback converter

Abstract

Lithium battery has become the main power source of new energy vehicles due to its high energy density and low self-discharge rate. In the actual use of the series battery pack, due to the internal resistance and self-discharge rate of batteries and other factors, inconsistencies between the individual cells are unavoidable. Such inconsistencies will reduce the energy utilisation rate and service life of the battery pack, and even endanger the safety of the battery systems. To improve the consistency of the series battery pack, a novel balancing method based on the flyback converter is proposed in this study. The flyback converter with a simple and reliable structure is used to realise the energy transfer between the whole battery pack and any single cell. Compared with the traditional balancing topology, the topology proposed in this study reduces the number of components and the volume of the balancing system, and only needs one set of control signals on the converter primary side, thus reducing the control difficulty. The experimental results show the effectiveness of the novel balancing method.