【作者】 王宇；

【导师】 王海英；

【作者基本信息】 哈尔滨理工大学 ， 控制理论与控制工程， 2021， 硕士

【摘要】 锂离子电池因其效率高、安全且寿命长的特点,在动力电池领域被广泛应用。单一的锂电池渐渐无法满足各类能源需求,因此常常需要将锂离子电池组合使用,即通过各种连接方式将若干锂离子电池组成电池组,以适应各种场景下的能源需求。然而,当成组使用锂离子电池时,单体电池之间的不一致是不可避免的问题。电池组的不一致性会对整体性能产生负面影响,并带来安全隐患。因此,研究一种有效的电池组不一致性诊断策略,准确地分选不一致性高的单体电池,对提高电池组性能,规避使用风险是极其重要的。对锂离子电池组的成组结构与原理进行了研究,分析了不一致性会产生的各种问题,包括不一致产生的原因,以及对电池组整体参数和外部特性的影响。研究表明,电池组的不一致性主要表现为容量,开路电压,欧姆内阻、极化内阻等参数的不一致。为了辨识这些参数,建立了电池组的Thevenin等效电路模型。选取需成组的单体锂离子电池进行最大容量测试、开路电压测试和阻抗谱测试,并分析单体电池及电池组SOC及SOH估计方法。实验测得了单体电池的最大可用容量、OCV-SOC曲线以及模型参数变化曲线,并通过计算获得了电池组的开路电压曲线和SOH,在充放电过程中采集单体电池的电压,电流,建立电池性能数据库。使用基于径向基核函数的支持向量机作为电池组不一致性的诊断算法,代入单体电池的容量以及5组SOC值对应的开路电压、欧姆内阻、极化内阻和极化电容进行训练和测试,诊断出电池组中不一致性较高的单体,对电池组不一致性的诊断准确率达到95%。再选取电池组进行性能测试,并进行不一致性诊断,将诊断出的不一致性高的单体电池替换为不一致性较低的单体电池后重新测试电池组,其性能优于替换前。更多还原

【Abstract】 Lithium-ion batteries are widely used in the field of power batteries because of their high efficiency,safety and long life.A single lithium battery is gradually unable to meet various energy needs,so it is often necessary to use lithium-ion batteries in combination,that is,to form a battery pack of several lithium-ion batteries through various connection methods to meet the energy needs in various scenarios.However,when lithium-ion batteries are used in groups,the inconsistency between the single cells is an inevitable problem.The inconsistency of the battery pack will have a negative impact on the overall performance and bring safety hazards.Therefore,it is extremely important to study an effective battery pack inconsistency diagnosis strategy to accurately sort single cells with high inconsistency to improve battery pack performance and avoid use risks.The group structure and principle of the lithium-ion battery pack are studied,and various problems caused by inconsistency are further analyzed,including the reason of inconsistency,the influence on the battery pack parameters,and the influence on the overall and external performance.Studies have shown that the consistency of the battery pack is mainly reflected in the capacity,open circuit voltage,ohmic internal resistance,and polarization internal resistance.In order to identify these parameters,the Thevenin equivalent circuit model of the battery pack is established.Select single lithium-ion batteries to be grouped for maximum capacity test,open circuit voltage test and impedance spectroscopy test,and analyze the SOC and SOH estimation methods of single cells and battery packs.The experiment measured the maximum usable capacity of the single battery,the OCV-SOC curve and the model parameter change curve,and obtained the open circuit voltage curve and SOH of the battery pack through calculations.The voltage and current of the single battery were collected during the charging and discharging process to establish Battery performance database.Use the support vector machine based on the radial basis kernel function as the diagnostic algorithm for battery pack inconsistency,and substitute the capacity of the single battery and the open circuit voltage,ohmic resistance,polarization internal resistance and polarization capacitance corresponding to the 5 groups of SOC values for training And test,diagnose the monomer with high inconsistency in the battery pack,and the diagnostic accuracy rate of the inconsistency of the battery pack reaches 95%.Then select the battery pack for performance test,and perform inconsistency diagnosis,replace the diagnosed single battery with high inconsistency with the lower inconsistency,and retest the battery pack.The performance is better than before replacement.更多还原