基于多物理过程约束的锂离子电池优化充电方法

Multiphysics-constrained Optimal Charging of Lithium-ion Battery

锂离子电池在快速充电过程中极易触发内部过热,并加速寿命衰退,因此在确保快速充电的同时主动约束锂离子电池重要中间物理状态具有重要意义。因此,提出一种基于多物理过程变量约束的电池快速充电方法。建立电-热-老化综合模型,并在典型充电场景下进行电热模拟精度验证;在此基础上,设计基于模型的荷电状态与内部温度估计方法,兼顾充电速度、温度约束与寿命衰退抑制,设计基于模型预测控制的快速充电策略。试验验证结果表明,所提出的充电策略能主动限制电池内部温度始终低于预定阈值,在相似的充电速度前提下,所提出的充电策略相比优选的恒流恒压充电法具有更低的寿命衰减速率,两者200次快充-放电循环的容量衰减分别为2.12%和4.88%。所提出的快速充电策略基于模型预测控制方法实现了电池内部状态的有效约束,综合提升了锂离子电池充电过程的快速性、安全性和耐久性。

The lithium-ion battery(LIB) is prone to the expected over-heating and quick degradation during the fast charging.Therefore, it is of great significance to constrain the key intermediate physical states of LIB actively within a reasonable range, while pursuing the speed of charging. Motivated by this, a multiple physics-constrained fast charging strategy is proposed for the LIB. A comprehensive electro-thermal-aging model is established and validated under typical charging scenarios. On this basis, a model-based observer is designed to estimate the state of charge and internal temperature of LIB in real time. Accounting for multiple conflicting objectives, i.e., the charging speed, temperature rise and degradation rate, a model predictive control-based strategy is proposed to optimize the charging process of LIB. Experimental results suggest that the proposed charging strategy can actively constrain the internal temperature of battery below the predetermined threshold. With a comparable charging speed, the proposed charging strategy leads to a slower degradation than the widely-used constant-current-constant-voltage charging strategy. The capacity decays within 200 charge-discharge cycles are 2.12% and 4.88%, respectively, for the two strategies. Based on the model predictive control, the proposed fast charging strategy constrains the battery internal states effectively, while a comprehensive promotion in terms of rapidity, safety and life extension is realized.