Energy inconsistency among Li-ion battery cells widely exists in energy storage systems, which contributes to the continuous deterioration of the system durability and overall performance. Researchers have proposed various kinds of battery energy equalizers to reduce such inconsistency. Among them, the inductor equalizer is a predominant type in fast equalization applications. However, it requires relatively more complex control than other types of equalizers. In order to reduce the control complexity of inductor equalizers, a bidirectional multi-input and multi-output energy equalization circuit based on the game theory is proposed in the present work. The proposed equalizer has the modularized circuit topology and the mutually independent working principle. A static game model is developed and exploited for the mathematical description and control analysis of an energy equalization circuit comprised of these equalizers. The feasible control of each equalizer was obtained by solving a series of linear equations for the Nash Equilibrium of the model among the states of charge of the battery cells. The complexity of equations grows linearly with the cell number. The equivalent simulation model for the four-cell equalization is established in the PISM software, where the operational data and simulation results justify the static game model and verify the control validation, respectively. It is concluded that the proposed inductor equalizer is suitable for large-scale battery strings in energy storage systems, electrical vehicles, and new energy power generation applications.

With the rapid development of energy internet and new energy-related industries, lithium-ion batteries are widely used in various fields due to their superior energy storage characteristics. To reduce the influence of the inconsistency of the individual cells in the battery pack, a switch array DC equalization circuit together with an acceleration information Gauss-Seidel (DAIGS) method is proposed. The aging factor is added in the system state matrix considering the battery time effect. In this method, the energy transfer path can be optimized by updating the switch control matrix in each iteration. Hence, it can avoid the repeated charging and discharging of the battery and also reduce energy loss in rapid equalization. A four-cell battery string equalization model simulation was built in the PSIM and the experiment was also carried out to prove the feasibility of the proposed method. It was verified that the DAIGS had better performance under the same precision or number of iterations.

Summary Lithium‐ion batteries play an important role in large‐scale energy storage systems. However, the power inconsistency of the battery packs restricts the developments of modern technologies in energy storage area. The motivation of the present study is to serve the growing needs of the energy balance for lithium‐ion battery packs. The present study proposes a flexible multiphase interleaved converter for the energy equalization of a lithium battery pack with series configuration. Moreover, the graph theory is applied to the analysis of equalization circuits. It is intended to establish a unified standard for the comparison. The parameter of average efficiency is considered as an important indicator to evaluate the performance of the equilibrium system. This mentioned method is verified by constructing a lithium‐ion battery pack with the equalization circuit. It is observed that the proposed multiphase interleaved converter has flexible characteristics, while it has low energy loss compared with the conventional methods. The proposed method simplifies the complex equalization circuits into graphs and facilitates the comparison of the average efficiency of the system. It is concluded that this method is a feasible and powerful for evaluating the battery equalization circuit. This approach can be applied for solving complex problems in other engineering applications.