基于SOC的电动汽车锂动力电池组主动均衡方法研究

发布时间：2018-07-26 10:02

【摘要】：在环境污染和能源危机的双重压力下,发展电动汽车成为汽车产业可持续发展的必由之路。作为电动汽车的动力来源,动力电池直接影响着整车性能。锂离子动力电池凭借其优越性能成为电动汽车理想动力源。而电动汽车应用中,锂离子单体电池需要通过串并联成组以满足电压、容量和功率要求。电池成组后不一致性的存在将降低电池组性能,缩短电池使用寿命,甚至带来安全隐患,因此对电池组进行均衡是十分必要的。(1)本文首先介绍了锂离子电池的基本结构和工作原理,对其主要性能参数进行了描述,分析了锂离子电池的电压、内阻、容量动态特性。接着分析了锂电池组单体不一致性成因,阐述了电压、内阻、容量不一致性原理,然后讨论了不一致性的消除方法,分析比较了分选法和均衡法的原理和特点,表明了采取均衡方法的必要性。(2)在分析了均衡电路的设计要求和各种均衡电路的优缺点的基础上,提出一种模块化的均衡电路。整个电池组被分成若干模块,模块之间均衡电路均衡器为反激变换器,多个模块可以同时进行均衡。模块内均衡电路均衡器为一个公用的buck-boost变换器,能量最高和最低的两个单体率先均衡。两个电路中能量转移路径分别为源模块/单体直接到目标模块/单体。模块间和模块内均衡器分别利用零电压开关和零电流开关方法减少开关损失,其具体工作原理也在文中进行了详细描述。(3)在所设计的均衡电路基础上提出了相对应的均衡控制策略。首先对目前几种均衡判据进行了分析,选取SOC作为均衡判据,给出了均衡过程判断与控制需要用到的相关参数。然后分别就模块间和模块内均衡过程进行了具体阐述,描述了均衡控制的总体原则,设计了各种可能情形的控制算法。其中模块间均衡采用能量最高的模块向能量最低的模块转移能量,能量次高的模块向能量次低的模块转移能量并以此类推的方式。模块内均衡采用能量最高单体向能量最低单体转移能量的方式。(4)最后进行了模块间、模块内和整个电池组的均衡实验,验证了本文所提出的主动均衡方法的效果。
[Abstract]:Under the double pressure of environmental pollution and energy crisis, the development of electric vehicle becomes the only way to the sustainable development of automobile industry. As the power source of electric vehicles, power battery directly affects the performance of the whole vehicle. Lithium-ion battery has become an ideal power source for electric vehicles by virtue of its superior performance. In the application of electric vehicle, lithium ion cell needs to meet the requirements of voltage, capacity and power by series-parallel connection. The existence of battery inconsistency will reduce the performance of battery pack, shorten the battery life, and even bring about the hidden danger of safety. Therefore, it is necessary to equalize the battery pack. (1) this paper first introduces the basic structure and working principle of the lithium ion battery, describes its main performance parameters, and analyzes the dynamic characteristics of the voltage, internal resistance and capacity of the lithium ion battery. Then, the cause of monomer inconsistency of lithium battery pack is analyzed, and the principle of voltage, internal resistance and capacity inconsistency is expounded, then the elimination method of inconsistency is discussed, and the principle and characteristics of separation method and equalization method are analyzed and compared. It shows the necessity of adopting equalization method. (2) on the basis of analyzing the design requirements of equalization circuit and the advantages and disadvantages of various equalization circuits, a modularized equalization circuit is proposed. The whole battery pack is divided into several modules. The equalizer between the modules is a flyback converter, and multiple modules can be equalized at the same time. The equalizer is a common buck-boost converter with the highest energy and the lowest energy. In the two circuits, the energy transfer path is the source module / unit directly to the target module / unit. Inter-module and intra-module equalizers use zero-voltage switches and zero-current switches to reduce switching losses, respectively. Its working principle is also described in detail in this paper. (3) based on the designed equalization circuit, the corresponding equalization control strategy is proposed. Firstly, several kinds of equalization criteria are analyzed, SOC is chosen as the equalization criterion, and the relevant parameters used in the judgment and control of the equalization process are given. Then, the equalization process between modules and within modules is described in detail, the general principle of equalization control is described, and control algorithms for various possible cases are designed. Among them, the module with the highest energy transfers energy to the module with the lowest energy, the module with the second highest energy transfers energy to the module with the lower energy, and so on. The transfer of energy from the highest energy cell to the lowest energy cell is adopted. (4) finally, the balance experiments between modules, modules and the whole battery pack are carried out to verify the effectiveness of the active equalization method proposed in this paper.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U469.72

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