基于SOC在线估算的锂电池组直接均衡技术

The existing equalization technologies cannot meet the requirements on balancing speed, efficiency and the applicability of the system structure for the series power supplies. This project plans to innovate the balancing topologies as the breakthrough of research on direct balancing technologies for large-scale lithium-ion battery packs. The multi-port direct equalizer topology is proposed to shorten the energy transmission paths, reduce the times of energy transmission and conversion. The optimization method for constructing large balancing system is put forward to develop the new balancing structures, increasing the system flexibility. Real-time estimation of the state of charge (SOC) of the battery is a crucial need in the growing fields of plug-in hybrid electric vehicles and smart grid applications. The accuracy of the estimation algorithm directly depends on the accuracy of the model used to describe the characteristics of the battery. Online adaptive parameter identification and State-of-Charge estimation for Lithium-ion battery cells are proposed to improve accuracy and robustness of online SOC estimation, providing the prerequisites for a truly balance. Prejudge method of imbalance in battery string in view of SOC change rate is established, as well as the pre-balancing control method under complex working conditions. Moreover, methods of formulating the balancing control strategy and path optimization algorithm under the complicated imbalanced condition with multi-energy transmission paths are suggested to achieve full interoperability and performance of each balancing process. The results of this project will provide the theoretical and technical foundation for improving the balancing technologies level and promoting the development of the storage power supply management and industrialization.

针对现有均衡技术还不能综合满足动力型串联储能电源对均衡速度、均衡效率和系统结构 实用性要求的问题，本项目拟以创新均衡电路拓扑为突破点，开展大型锂离子电池组的直接均衡技术研究。首先建立多端口直接均衡器拓扑，缩短均衡能量传输路径，减少能量转换、变换环节；建立大型均衡系统结构优化设计方法，创建新型均衡系统架构，提高系统组合灵活度；建立电池等效模型参数在线辨识方法及SOC在线估算算法，提高SOC在线估算的准确性和鲁棒性，为真正意义的均衡提供条件；建立基于单体SOC变化率的电池组失衡预先判断方法，及复杂工况下电池组的预先均衡控制策略；制定复杂失衡状态和多均衡能量通道条件下的均衡控制策略和路径优化算法，充分发挥各均衡环节的协同能力和作用效能。本项目的研究成果将为提升均衡技术水平，促进储能电源管理技术的发展和产业化进程提供理论及技术基础。

在大型储能用锂离子电池组的应用中，均衡系统是电池组安全高效运行的保障。本项目以创新均衡电路拓扑为突破口，开展锂离子电池组的主动均衡技术研究，建立兼顾均衡速度、均衡效率、系统结构实用性的大型串联储能电源均衡系统分析和优化设计方法。通过提出新型均衡电路拓扑及引入最优化建模分析方法，解决了提高均衡速度，降低均衡损耗，以及改善系统结构实用性问题。取得的主要成果有：提出一种基于图论的均衡系统结构合理性量化分析方法，利用有向图和赋权可达矩阵对串联电池组均衡系统进行建模，实现均衡器性能的量化评价；提出几种直接均衡电路拓扑，实现从单一均衡模式到多种模式共存的改进，提高均衡灵活性以应对复杂失衡情况，同时提高均衡效率和均衡速度；提出一种串联储能电源直接均衡器组合结构，解决了现有储能单体均衡拓扑单体对单体能量均衡路径长和能量均衡效率低的问题，同时提高均衡系统扩展灵活性；基于电池温度特性实验，通过引入温度耦合PNGV模型，实现基于AEKF的宽温度范围SOC估计，提高估算精度；针对双层混合式均衡系统，对长串联电池组复杂失衡条件下均衡效率和均衡速度进行建模，建立以效率最优及速度最优为原则的均衡优化控制模型，确定相应的约束条件，并提出采用蚁群算法对所提出的优化模型进行求解，提高均衡系统的效能。本项目的研究成果为提升主动均衡技术水平，促进储能电源管理技术的发展和产业化进程提供理论及技术基础。截至本报告时间，项目共发表学术论文10篇，其中英文SCI论文6篇、中文期刊论文1篇。共申请专利7项，其中已授权2项，实质审查中5项。