摘 要

为了解决能源危机的问题与改善环境污染的现状，电动汽车的研究已经成为汽车行业的发展所必需的重要一步.而新能源汽车以其节约能源、污染小、噪音小等优势，近年来逐渐进入了科研人员及普通民众的视野中，发展迅速，为汽车行业带来了新的机遇，推动了汽车行业发展的一大步。而动力电池作为电动汽车的关键部分，对它的研究进展将直接影响到电动汽车的发展进程。随着电动汽车的使用时间不断增加，动力电池的不断充放电，电池的电量会逐渐衰减，因此，会导致电池性能的下降。在动力电池管理系统中，对SOH的估算是研究和改善动力电池性能的关键一步，准确的估算SOH能够为电池的性能诊断及改善提供有效可靠的数据支撑。

本文分析了动力电池与新能源汽车的发展现状，了解到目前新能源汽车可以分为纯电动汽车、混合动力汽车、燃料电池汽车等，而动力电池作为新能源汽车的核心部分，其性能的好坏与发展的趋势决定了新能源汽车的发展状态。而动力电池可分为镍氢电池、铅酸电池和锂离子电池、燃料电池和超级电容器等，其中，锂离子电池运用广泛，是动力电池中很重要的组成部分。因此，本文以某款35Ah三元材料锂离子单体电池为研究对象，搭建了合适的参数特性实验平台，通过控制放电电流分别为1C、2C、3C和工作温度分别为0℃、25℃、45℃，对该锂离子电池的外特性进行探究。得到的结论为：放电刚开始和结束前的一小段时间内电池的电压下降速率很快，而放电中期的较长一段时间，放电速率变缓慢且基本保持稳定；锂离子电池的SOC在90%以上以及20%以下的时候，电池开路电压的下降速率很快，且明显高于SOC处于20%至90%之间时的电压下降速率。

选用Thevenin等效模型，并进行了HPPC测试，利用实验数据进行电池开路电压U_OCV与欧姆内阻R₀的辨识，通过离线拟合的方法完成了极化电阻R_p、极化电容C_p与时间常数τ的辨识。

随后给出了动力电池SOH的定义以及研究的意义，提出了利用双重无迹卡尔曼滤波算法来进行电池SOC以及欧姆内阻的估算，并在simulink中建立相应的模型并进行模拟仿真，最后将模拟仿真得到的数据与实验测得的真实数据相比较，可以看出25℃时不同放电倍率下得到的电池SOC随时间的变化曲线，相对误差在2.5%以内，因此，验证了双重UKF估算电池内阻的可行性。

关键词：三元材料锂离子单体电池；电池SOH的估算；Thevenin等效模型；双重UKF算法。

Abstract

To solve the energy crisis and improve the status of environmental pollution, the study of electric vehicles has become an important step in the development of the automotive industry. New energy vehicles, its energy saving, pollution, noise and other advantages, in recent years has gradually entered the field of scientific research and the public, the rapid development of the automotive industry has brought new opportunities to promote the development of the automobile industry a big step. Power battery as a key electric car, its research will directly affect the progress of the development of electric vehicles. The use of electric vehicles to continue to increase the power of the battery charge and discharge, the battery will gradually decay, therefore, will lead to battery performance. In power battery management systems, SOH estimation is a key step in the improvement and research of power battery performance, and accurate estimation of SOH can provide effective and reliable data support for diagnosing and improving battery performance.

This paper analyzes the development of power batteries and new energy vehicles, to understand the current new energy vehicles can be divided into pure electric vehicles, hybrid cars, fuel cell vehicles, and power batteries as the core of new energy vehicles, its good performance Bad and development trend determines the development of new energy vehicles. The power battery can be divided into nickel-metal hydride batteries, lead-acid batteries and lithium-ion batteries, fuel cells and super capacitors, etc., of which lithium-ion battery is widely used in power batteries is a very important part. In this paper, a 35 Ah ternary material lithium-ion battery is used as the research object. The experimental parameters are designed. The control discharge current is 1 C, 2 C, 3 C and the working temperature are 0 ℃, 25 ℃, 45 ℃, the lithium-ion battery to explore the external characteristics. The conclusion is that the voltage drop rate of the battery is very fast at the beginning and the end of the discharge, and the discharge rate becomes slow and remains stable for a long period of time in the middle of the discharge. The SOC of the lithium ion battery is 90% And below 20%, the battery open-circuit voltage drops rapidly and is significantly higher than the voltage drop rate between 20% and 90% of the SOC.

The Thevenin equivalent model was selected and the HPPC test was carried out. The experimental data were used to identify the open circuit voltage U_OCV and ohmic resistance R₀. The polarization resistance R_p, the polarization capacitance C_p and the time constant τ were completed by the off-line fitting method. Identification.

Then, the definition of SOH and the significance of the research are given. The method of using the double unscented Kalman filter is proposed to estimate the SOC and the internal resistance of the battery. The corresponding model is established in Simulink and the simulation is carried out. Finally, compared with the experimental data, the relative error of the battery SOC is 2.5% at 25 ℃, and the relative error is within 2.5%. Therefore, it is verified that the double UKF estimation battery the feasibility of internal resistance.

Keywords: Ternary materials lithium-ion battery; SOH estimation; Thevenin equivalent model；dual UKF algorithm

目录

第1章 绪论 1

1.1研究背景及意义 1

1.2研究现状 2

1.2.1动力电池研究现状 2

1.2.2 SOH估算方法研究现状 3

1.3 主要研究内容与方法 4

第2章 三元锂离子电池特性 5

2.1 锂离子电池的结构与工作原理 5

2.2 三元锂离子电池的性能参数 6

2.2.1 电池电压 6

2.2.2 电池内阻 6

2.2.3 电池容量 6

2.2.4 充放电倍率 7

2.2.5 比能量和比功率 7

2.3 电池的参数特性实验 7

2.3.1 实验对象与实验平台 7

2.3.2 电池参数特性实验 8

2.3.3 实验结果与分析 9

2.4 本章小结 11

第3章 电池模型的建立与验证 13

3.1 常见的等效电路模型 13

3.1.1 Rint模型 13

3.1.2 Thevenin模型 13

3.1.3 PNGV模型 14

3.1.4 Massimo Ceraolo模型 14

3.2 电池等效电路模型的确定 15

3.3 电池模型的初始参数辨识 15

3.3.1 HPPC测试 15

3.3.2 开路电压和欧姆内阻的辨识 16

3.3.3 极化电阻和极化电容的辨识 19

3.4 本章小结 22

第4章 三元锂离子电池SOH的估算 23

4.1 电池SOH的定义 23

4.2 双卡尔曼滤波器的原理 23

4.2.1 卡尔曼滤波算法 23

4.2.2 双重无迹卡尔曼滤波算法的原理 25

4.3 利用双重UKF估算电池内阻 28

4.3.1 Thevenin等效电路的空间模型 28

4.3.2 利用双重UKF估算电池SOC与内阻 29

4.4 模拟仿真与对比分析 30

4.5通过R₀估算锂离子电池SOH 33

4.6 本章小结 33

第五章 结论 34

5.1 全文总结 34

5.2 研究展望 35

致 谢 36

参考文献 37