No abstract

Batteries are used in various combinations in various fields. Research on single-cell batteries is well underway and is approaching a stabilization phase. However, problems caused by battery combinations are still insufficiently studied. The purpose of this study was to investigate the cause of fires due to gradual damage in a large-capacity energy storage system (ESS). In the paper Energy Storage System Safety Operation Plan by Preventing Overcharge During Relaxation Time, which was based on the fact that most fires in large-capacity energy storage devices occurred during the diastolic period, it was proven that the inflow of compensation current due to a voltage imbalance in the cell was the cause. The total amount of compensation current is determined by the voltage deviation of the battery. Batteries connected in series have different rates of aging due to differences in their capacities. Thus, with use, the total amount of compensating current continues to increase until a fire occurs. In this study, by analyzing the effect of battery-capacity deviation on the aging of individual cells, it was confirmed that the capacity deviation increased as the battery was used, resulting in an increase in the total amount of compensation current. In addition, if a solution to the problem is presented and the proposed solution is applied, the allowable range of battery-capacity deviation will be widened. We used Matlab 2009a, assuming a real environment. Using Simulink, problems were identified through simulation, improvement measures were suggested, and the proposed method was verified via simulation.

This paper analyzes the cause of electric vehicle battery fires. The fundamental cause is attributed to a low cell balance current, and it is proven that the variation in the battery’s internal voltage due to temperature change is the decisive reason for battery fires. In this paper, the authors studied a method of solving the problem by changing only the software of the existing Battery Management System (BMS) without changing the hardware. Batteries cannot be made with 100% capacity, resulting in voltage division. Cell balancing is performed to prevent such phenomena, but a low cell balance current prevents the proper operation of cell balancing. As a result, relatively small batteries, due to progressive degradation, have continuous voltage rise toward overvoltage. Subsequently, an additional voltage rise occurs as the chemical activity of the battery increases due to temperature rise. In this paper, a new cell balancing method is proposed to limit the aging process of cells with a relatively small capacity and peak voltage. In addition, it was validated through simulation using MATLAB R2019a.