Design and Analysis of Composite DC-DC Converter Structure for Battery SOC Balance System

Lithium batteries are widely used in electric vehicles (EVs) energy storage systems because of their long life and high energy density. This paper presents an active state-of charge (SOC) balancing system architecture for EVs utilizing isolated DC-DC power converters. The system consists of multiple battery cells connected in series and parallel with different DC-DC converters. By adjusting the duty cycle of each converter, not only the active SOC balancing of the battery can be realized, but also the continuous and stable power supply to both high-voltage and low-voltage loads can be provided simultaneously without additional power loss. In this paper, the working principle of this system architecture is described in detail, and a simulation model is built using Matlab/Simulink to verify the experiment.