| Author Name | Affiliation | | Yening Sun | Key Lab of Power Electronics for Energy Conservation and Motor Drive of Hebei Province, Electrical Engineering College, Yanshan University, Qinhuangdao 066004, Hebei, China | | Jinlong Zhang | Key Lab of Power Electronics for Energy Conservation and Motor Drive of Hebei Province, Electrical Engineering College, Yanshan University, Qinhuangdao 066004, Hebei, China | | Hanhong Qi | Key Lab of Power Electronics for Energy Conservation and Motor Drive of Hebei Province, Electrical Engineering College, Yanshan University, Qinhuangdao 066004, Hebei, China | | Chunjiang Zhang | Key Lab of Power Electronics for Energy Conservation and Motor Drive of Hebei Province, Electrical Engineering College, Yanshan University, Qinhuangdao 066004, Hebei, China |
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| Abstract: |
| In this paper, battery aging diversity among independent cells was studied in terms of available capacity degradation. During the aging process of LiFePO4 batteries, the phenomenon of aging diversity can be observed. When batteries with same specification were charged and discharged repeatedly under the same working conditions, the available capacity of different cell decreased at different rates along the cycle number. In this study, accelerated aging tests were carried out on multiple new LiFePO4 battery samples of different brands. Experimental results show that under the same working conditions, the actual available capacity of all cells decreased as the number of aging cycle increased, but an obvious aging diversity was observed even among different cells of same brand with same specification. This aging diversity was described and analysed in detail, and the common aging features of different cells beneath this aging diversity was explored. Considering this aging diversity, a probability density concept was adopted to estimate battery’s state of health (SOH). With this method, a relationship between battery SOH and its aging feature parameter was established, and a dynamic sliding window optimization technique was designed to ensure the optimal quality of aging feature extraction. Finally, the accuracy of this SOH estimation method was verified by random test. |
| Key words: LiFePO4 battery aging diversity SOH estimation probability density sliding window optimization |
| DOI：10.11916/j.issn.1005-9113.2020022 |
| Clc Number:TM92 |
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| Descriptions in Chinese: |
| 磷酸铁锂蓄电池老化差异分析及SOH估算 孙叶宁, 张金龙*，漆汉宏, 张纯江 （燕山大学电气工程学院 电力电子节能与传动控制河北省重点实验室，秦皇岛 066004） 创新点说明：本论文重点针对磷酸铁锂电池在全寿命周期老化过程中的容量衰减差异特性展开研究，在完全相同的测试工况下，分析两种典型LiFePO4电池不同单体间存在的容量衰减差异特性；进而采用老化特征提取的思想，针对该问题设计一种带有滑窗优化机制的概率密度函数(PDF, probability density function)法对电池健康状态(SOH, state of health)进行估算。 中文说明： 描述和分析LiFePO4电池在老化过程中存在的容量衰减差异现象；并基于此设计一种广泛适用的、便于工程实现的、同时具有良好精度的电池SOH估算方法。首先选取两种典型的LiFePO4电池样本，而后设计加速老化测试方案，接着采用循环充放电设备对电池样本进行全寿命周期循环测试，直至所有的电池寿命终止；收集样本电池全寿命周期的外特性和容量衰减数据，重点分析同品牌同型号不同单体间的容量衰减差异特性；引入概率密度思想，基于电池标准充电曲线提取其老化特征，建立老化特征与电池SOH之间的关系，并设计动态滑窗策略实现电池SOH与其老化特征之间关系的最优化提取；最后对所设计的SOH估算方案的性能进行测试与验证。研究结果表明，在两种典型品牌的LiFePO4电池的全寿命周期老化过程中，均存在不同程度的容量衰减差异现象，对于工程应用的电池管理技术而言，该现象是不可忽略的问题；此外，本文设计的SOH估算方案可以适应这种电池容量衰减差异，实现对不同品牌LiFePO4电池健康状态的准确估算。相对其他类似方案而言，本方案具有更加广泛的适用性和良好的精度，且工程实现较为方便，可以为LiFePO4蓄电池的高效利用及电池管理技术的进一步完善提供参考。 关键词：LiFePO4电池；容量衰减差异；SOH估算；概率密度；滑窗优化 |
