串联动力电池六单体直接均衡器研究

发布时间：2018-02-24 03:26

本文关键词： 均衡拓扑动力锂离子电池组图论均衡效率　出处：《哈尔滨工业大学》2014年硕士论文　论文类型：学位论文

【摘要】：动力锂离子电池作为储能设备应用于人造卫星、电动汽车和不间断电源等领域时，为了满足电压等级的要求，通常需要几十节甚至上百节串联使用。在串联电池组的使用过程中，由于各单体电池参数的不一致性，使单体之间电压出现不平衡，进而导致电池组的有效使用容量降低，循环寿命减少。因此，为了提高串联电池组的工作性能，开展锂离子电池均衡技术的研究是十分必要的。本文将图论中的有向图和赋权矩阵引入到均衡拓扑结构的分析中，分别建立了典型结构的有向图及赋权矩阵描述，重点研究了均衡结构本身对能量传递路径的影响，在此基础上，归纳总结出理想均衡拓扑的有向图描述，明确了理想均衡拓扑中任意两个单体间都应有能量的直接流通路径，分析了理想均衡拓扑的可实现性，为寻求新型拓扑结构提供了理论指导。在对现有拓扑结构分析的基础上，提出了一种基于多输出绕组变压器的均衡拓扑，该拓扑可以在两步内实现任意单体间能量的直接传递。本文以六单体为例详细阐述该拓扑的工作原理，依据变压器绕组同名端的位置将六节单体电池分为两组，根据组间和组内的不同失衡情况令该拓扑工作于三种模式，即反激模式、无输出电感正激模式和反激-反激模式，力求在不同失衡条件下均能实现快速、有效的均衡；对主电路的电磁元件和双向开关等进行了设计；分析了变压器漏感等参数对均衡器效率的影响，为进一步提高均衡器的效率提供理论依据。依据六单体直接均衡拓扑的工作模式分析，设计了六单体均衡器的控制电路。采用电池监测芯片LTC6802-1实现电池电压的采样，以提高采样精度、简化采样电路结构；为了避免双向开关中均衡电流可能在过零后继续反向增大而引起均衡器工作过程紊乱、均衡效率降低的问题，本文设计了均衡电流采样与逻辑判断单元；依据串联电池组可能出现的多种失衡情况，制定了六单体均衡器的均衡策略，设定了各双向开关的动作规则，，确保了均衡器可靠、有序运行。针对50Ah的动力锂离子电池，搭建了六单体均衡器，分别在不同失衡条件下对均衡效果进行了实验测试及分析。实验结果表明，六单体直接均衡拓扑可以实现能量在任意单体间直接传递，使动力锂离子电池组得到准确、快速的均衡。
[Abstract]:Power lithium-ion batteries are used as energy storage equipment in the fields of artificial satellites, electric vehicles and uninterruptible power supply, in order to meet the requirements of voltage level. In the process of using series battery, because of the inconsistency of the parameters of each single cell, the voltage between the cells is unbalanced, which leads to the decrease of the effective service capacity of the battery. Therefore, in order to improve the performance of series batteries, it is necessary to study the equalization technology of lithium ion batteries. In this paper, the directed graph and weighted matrix in graph theory are introduced into the analysis of equilibrium topological structure, and the directed graph and weight matrix description of typical structure are established, respectively, and the influence of equilibrium structure on energy transfer path is studied emphatically. On this basis, the directed graph description of ideal equilibrium topology is summarized, the direct flow path of energy between any two units in ideal equilibrium topology is defined, and the realizability of ideal equilibrium topology is analyzed. It provides theoretical guidance for seeking new topology. Based on the analysis of the existing topology, a balanced topology based on multi-output windings transformer is proposed. The topology can realize the direct transfer of energy between arbitrary cells in two steps. In this paper, the working principle of the topology is explained in detail by taking six monomers as an example, and the six single cells are divided into two groups according to the location of the same end of the transformer winding. According to the different imbalance between groups and within groups, the topology works in three modes, that is, flyback mode, no output inductor forward mode and flyback mode, which can achieve fast and effective equalization under different unbalanced conditions. The electromagnetic components and bidirectional switches of the main circuit are designed, the influence of transformer leakage inductance and other parameters on the efficiency of the equalizer is analyzed, which provides a theoretical basis for further improving the efficiency of the equalizer. According to the working mode analysis of six-cell direct equalization topology, the control circuit of six-cell equalizer is designed. The battery monitor chip LTC6802-1 is used to realize the sampling of battery voltage in order to improve the sampling accuracy and simplify the sampling circuit structure. In order to avoid the problem that the equalization current may continue to increase in reverse direction after zero crossing in bidirectional switch, the equalizer working process is disturbed and the equalization efficiency is reduced. In this paper, the equalization current sampling and logic judgement unit are designed. According to the possible imbalance situation of series battery, the equalization strategy of six-monomer equalizer is formulated, and the action rules of each two-way switch are set up to ensure the reliable and orderly operation of the equalizer. A six-monomer equalizer was built for 50 Ah power lithium-ion battery. The equalization effect was tested and analyzed under different unbalance conditions. The experimental results showed that, The six-cell direct equalization topology can realize the direct energy transfer between any single cell and make the power lithium ion battery pack accurate and fast equalization.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912

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