串联电池组主动均衡拓扑及控制策略研究

电池单体以串、并联的形式构成电池组,广泛应用于各类储能系统中。由于制造工艺和使用环境的不同,以及电池单体间内阻、库伦效率等参数的不一致在反复充放电后形成电池组电量的不均衡,导致电池组可用容量下降、电池组整体功率衰退等。为此,针对串联电池组提出了一种包括基于正激变换器的双向DC/DC变换器及开关阵列的主动均衡电路拓扑。在主电路工作原理分析的基础上,进一步提出了一种基于聚类分析的SOC均衡控制策略,并以8节电池单体串联构成电池组进行均衡验证实验。实验结果表明经过均衡操作后,不均衡电池组可用容量有所提升,证明了均衡策略及均衡系统的有效性。与传统的“平均差”法可用容量提升2.6%相比,所提出的均衡策略可用容量提升10.8%,提升效果更明显,在均衡时间基本一致的前提下,对电池组一致性改善效果更好。

Research on Active Equalization Topology of Series Battery Pack and Its Control Strategy

Battery packs in the form of series or parallel connected battery cells are widely applied to various kinds of energy storage systems. Due to the differences in manufacturing processes and usage environments, inconsistent parameters such as internal resistance and coulombic efficiency between battery cells will lead to an imbalance in power consumption after repeated charging and discharging, resulting in the decline of the battery pack''s available capacity as well as the degradation of its overall power. To solve this problem, an active equalization circuit topology for series battery pack is proposed, which includes a bidirectional DC/DC converter originating from a forward converter and a switch matrix. Based on the analysis of the working principle for the main circuit, an state-of-charge(SOC) equalization strategy based on clustering analysis is further put forward. An equalization verification experiment on a battery pack consisting of 8 series-connected battery cells was carried out. Results show that the available capacity of the unbalanced battery pack increased after the equalization operation, which proves the effectiveness of the equalization strategy and the equalization system. Compared with the traditional "mean-difference" method(with an available capacity improvement of 2.6%), the proposed equalization strategy(with an improvement of 10.8%) improves the consistency of the battery pack better and increases its available capacity more significantly, even though the equalization time for both methods is nearly the same.