A novel high-efficient Lithium-ion battery serial formation system scheme based on partial power conversion

The formation of the battery is a crucial step in its manufacturing process. The existing battery formation system suffers from low efficiency and high energy consumption costs due to long energy flow paths, high DC bus line losses, and additional balancing circuit applications. Therefore, a novel high-efficient battery series formation system (BSFS) that combines partial power processing architecture (PPPA) with the modular converter is proposed to address this problem in this article. The PPPA-BSFS includes two-stage isolated sub-modules consisting of Buck-Boost converter and LLC converter with input-serial and output-parallel connection. The isolated converter only processes the serial compensation power, about 1/3 of the full power. Consequently, the converter capacity can be shrunk in the PPPA-BSFS, which can reduce the system's cost and power loss. Furthermore, the paper establishes the steady-state mathematical model and energy efficiency model of PPPA-BSFS based on analyzing the power compensation principle, and the key factors affecting the operational efficiency of PPPA-BSFS are studied. Finally, we construct the simulation models with 10 cells and 120 cells to compare and analyze energy efficiency between PPPA-BSFS and existing battery formation topology under various operating conditions. Our simulation results show that the highest operating efficiency of the PPPA-BSFS proposed is 99.37 % when 120 cells are formed normally, where there is an increment of 5.95 %, 2.36 %, and 0.85 % compared with others, respectively. The high efficiency of the PPPA-BSFS is verified, and the PPPA-BSFS shows great potential for application in battery formation scenarios.