锂离子电池组健康状况评估方法研究

发布时间：2018-03-19 13:50

本文选题：锂离子电池　切入点：电池组　出处：《武汉理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：当今世界，环境和能源问题日益突出，电动汽车的出现顺应时代潮流，在一定程度上缓解了危机。但目前电动汽车尚未普遍流行，其主要原因是电动汽车的动力电池性能还不能满足要求。锂离子电池以相对优越的性能，成为电动汽车动力电池的主流，锂离子电池性能的研究也成为热点。有关锂离子电池的研究除了电池本身的化学材料研究外，对电池管理系统的研究也如火如荼，但目前还停留在对剩余电量的精确估算，均衡控制策略，而对电池组健康状况的评估是目前电池管理系统的薄弱环节。电池组健康状况（State of Health，SOH）描述了电池组随着使用次数的增加，实际容量不断衰减的过程。本文在阐述锂离子电池工作原理的基础上，论述了电池内部电极材料，电解质溶液，电极极柱等对电池衰减的影响；同时也分析了作用于电池的外部因素如充放电倍率，充放电截止电压，温度，连接方式等对电池性能的影响。一般对电池SOH的研究主要集中在估算单体电池的SOH，对成组电池的SOH研究较少。本文提出从单体电池SOH和电池组的一致性两方面评估电池组的健康状况。通过建立单体电池模型，设计实验对模型进行参数辨识，获得电池内部特性。在对比不同电池的极化内阻与欧姆内阻之后，确定欧姆内阻对电池性能有重要影响，进而从剩余电量与欧姆内阻两方面评估电池组的一致性。根据电池在整个生命周期中可放出电量约为常数，所以可以确定单体电池的SOH，最后从单体电池SOH和电池组的一致性两方面评估电池组的SOH。在对电池组SOH评估的基础上，本文对当前的电池管理系统进行了改进。目前的电池管理系统主要以端电压作为控制策略的判断依据，但实际上由于内阻的存在，端电压不能准确反映电池的剩余电量，所以为消除内阻的影响，，本文在参数辨识的基础上，以开路电压作为充放电截止判断的依据。另一方面，传统的均衡策略是对当前电压最低的电池进行均衡，但事实上电压不能准确反映电池剩余电量，本文从均衡的本质及保护电池组的角度出发，提出对最低电量电池采用轮换均衡的方法，使各个电池性能保持一致，同时延长电池组寿命。
[Abstract]:In today's world, environmental and energy problems are becoming increasingly prominent. The emergence of electric vehicles conforms to the trend of the times and alleviates the crisis to a certain extent. The main reason is that the power battery performance of the electric vehicle can not meet the requirements. Lithium ion battery has become the mainstream of the electric vehicle power battery with its relatively superior performance. Besides the study of the chemical materials of the battery itself, the research on the battery management system is also in full swing, but at present it is still in the accurate estimation of the remaining electricity quantity. Balanced control strategy, and the assessment of battery health is the weak link of the cell management system. The state of health of battery pack describes the process that the actual capacity of the battery decreases with the increase of the number of times of use. On the basis of explaining the working principle of lithium ion battery, the paper discusses the electrode material and electrolyte solution inside the cell. At the same time, the effects of external factors such as charge / discharge rate, cutoff voltage, temperature and connection mode on the battery performance are also analyzed. In general, the research on SOH is mainly focused on estimating the Soh of the single cell, but less on the SOH of the grouped cell. This paper proposes to evaluate the health status of the battery from the aspects of the consistency between the SOH and the battery. Single cell model, After comparing the polarization and ohmic internal resistance of different batteries, it is determined that the ohmic internal resistance has an important effect on the performance of the battery. Then the consistency of the battery pack is evaluated in terms of the residual charge and the ohmic internal resistance. So we can determine the Soh of the single cell, and finally evaluate the SOH of the battery from two aspects: the SOH of the cell and the consistency of the battery. Based on the evaluation of battery pack SOH, the current battery management system is improved in this paper. The current battery management system mainly uses terminal voltage as the judgment basis of control strategy, but in fact, because of the existence of internal resistance, The terminal voltage can not accurately reflect the residual quantity of the battery, so the influence of internal resistance is eliminated. Based on the parameter identification, the open circuit voltage is used as the basis of the cutoff judgment of charge and discharge, on the other hand, The traditional equalization strategy is to equalize the cell with the lowest voltage, but in fact, the voltage can not accurately reflect the residual quantity of the battery. In this paper, the essence of the equalization and the protection of the battery pack are discussed. The rotation equalization method for the lowest battery is proposed to keep the cell performance consistent and prolong the battery life at the same time.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912

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