Research On Charging Strategy For Lithium-ion Battery Pack Based On Improved Single Particle Model

Lithium-ion battery has been widely used in the energy industry as a kind of core energy storage device due to its advantages. The battery management system has been put forward higher demands, and the efficient and healthy charging method of lithium-ion battery has drawn more and more attention. This research focus on charging strategy of lithium-ion battery pack, and a long-life and quick charging mode and a equalization control scheme based on the improved single particle model are proposed, which provide ideas for the electrochemistry model in the application of the management system.Firstly, the internal physical or chemical process of the improved single particle model is analyzed in detail. Afterwards, the relationship between model parameters and the cell terminal voltage is deeply excavated. Different charge-discharge conditions are adopted to identify model parameters step by step using the excitation response analysis. The speed and result accuracy of identification method can be verified via the experiment of LiCoO2 batteries. And the precise results can be used in study of state estimation and health management.In order to achieve the lithium-ion battery charging quickly and safely, the ageing mechanism in the process of charging is expounded systematically in this paper. On the foundation of the traditional charging mode, a long-life and quick charging mode is proposed by monitoring solid phase lithium-ion concentration ratio in the surface of negative electrode particles, which combines with the improved single particle model and parameters. Then the charging experiment is carried out on the experimental platform. The result shows that the method improves the charging efficiency and depth, and prolongs the battery useful cycle life evidently.According to the disadvantages of previous schemes in battery pack equalization technology, an equalization control scheme on the basis of battery SOC estimation is developed in this paper. After acquiring the parameters of the improved single particle model, the extended Kalman filter algorithm is apply to estimate SOC. The estimated SOC shows good agreement with the real ones under various operating scenarios. Applicability and robustness of the proposed method are also assessed considering the influencing factors such as initial errors and measured noise. Meanwhile, the non-dissipative equalization topology based on inductor is designed. With the analysis of working principle of the circuit, the equalization process is determined concretely.At last, the experiment system platform is built for conducting charging test including the long-life and quick charging mode and the equalization control scheme for lithium-ion battery pack. The batteries with higher consistency are selected by clustering algorithm to guarantee satisfactory reliability and precision of the experiment. Research results provide feasibility and validity of the charging strategy for lithium-ion battery pack, and weaken the battery pack usage capacity degeneration.