锂离子电池成组SOC精确估算的建模与优化

The state of charge (SOC) estimation is very important for the energy management of lithium-ion battery pack. Due to the difficulty of group equivalent modeling and accurate estimation, the imprecision of group SOC estimation under complex dynamic conditions has not yet been effectively solved. (1) Aiming at the problem of group equivalent modeling of lithium-ion battery, the design idea of composite equivalent circuit model is innovatively proposed. Through the equivalent representation of modular circuit and the establishment of state space equation, the accurate mathematical description of working characteristics is achieved. (2) For high stability of SOC estimation under the complex condition, the feedback correction mechanism based on Unscented Kalman can be used, in which the simplified unscented transformation is introduced, the particle weight calculation process is improved and the aging coefficient can be super-posited, building a new SOC estimation model for the battery pack.(3) As for the difference characterization among the battery cells and its correction problem in the SOC estimation process, a new concept state of balance (SOB) is put forward innovatively for the first time. The combination consisted of model parameters and weight factors are embedded into the applications to realize the equivalent modeling and SOC iterative process, eliminating the imbalance state among the battery cells and its impact on the pack SOC estimation accuracy. Finally, the influence of complex working conditions on the estimation process will be revealed and an online accurate SOC estimation model can be built, which will lay a foundation for the critical breakthrough of the SOC estimation for the lithium-ion battery pack.

荷电状态（SOC）估算对锂离子电池组的能量和安全管理至关重要，然而成组等效建模和精确估算困难，复杂动力工况下的成组SOC估算不精确问题至今尚未有效解决。(1)针对锂离子电池成组等效建模问题，在前期独创性研究基础上提出复合等效电路模拟新思路，通过模块化电路等效表征，构建状态空间方程以实现工作特性的准确数学描述。(2)针对复杂工况下高稳定性SOC估算问题，利用无迹卡尔曼为基础的反馈修正机制，引入精简粒子无迹变换，改进权值计算过程并叠加老化系数，构建成组SOC估算新模型。(3)针对单体间一致性差异描述及其在成组SOC估算中的修正问题，应用平衡状态（SOB）这一新理念，将模型参数与权重因子相结合，嵌入应用于等效建模和SOC迭代计算中，以消除单体间不一致对成组SOC估算精度的影响。本研究将揭示复杂工况对SOC估算的影响机制并构建精确SOC估算模型，为锂离子电池成组SOC估算关键性突破奠定基础。

荷电状态（SOC）估算对锂离子电池组的能量和安全管理至关重要，然而成组等效建模和精确估算困难，复杂动力工况下的成组SOC估算不精确问题至今尚未有效解决。(1)针对锂离子电池成组等效建模问题，在前期独创性研究基础上提出复合等效电路模拟新思路，通过模块化电路等效表征，构建状态空间方程以实现工作特性的准确数学描述。(2)针对复杂工况下高稳定性SOC估算问题，利用无迹卡尔曼为基础的反馈修正机制，引入精简粒子无迹变换，改进权值计算过程并叠加老化系数，构建成组SOC估算新模型。(3)针对单体间一致性差异描述及其在成组SOC估算中的修正问题，应用平衡状态（SOB）这一新理念，将模型参数与权重因子相结合，嵌入应用于等效建模和SOC迭代计算中，以消除单体间不一致对成组SOC估算精度的影响。本研究完成了锂离子电池组工作特性研究，获得了不同工况下电池组的工作特性。完成了锂离子电池组等效模型构建，构建了状态空间方程并进行了数学描述。进行了成组SOC估算方法研究与建模，构建了具有自适应能力的SOC估算模型，且完成了模型参数修正和实验验证，解决了单体间不平衡影响估算结果这一问题，为电池组提供了有效SOC估算方法。本研究提出的锂电池的动态温度RC模型表征新策略，关键参数检测精度高达1.57%；提出的改进补偿扩展卡尔曼新算法，与EKF算法相比较，在BBDST实验中，平均误差减小了1.55%，最大误差减小了4.35%。本研究将揭示复杂工况对SOC估算的影响机制并构建精确SOC估算模型，为锂离子电池成组SOC估算关键性突破奠定基础。