셀프에너지 밸런싱을 고려한 리튬이온전지용 BMS의 운용알고리즘에 관한 연구

Abstract

Recently, according to the green growth and carbon-neutral policy of government, installation of ESS(energy storage system) with various functions such as peak shaving, frequency regulation and output stabilization of renewable energy sources is rapidly increasing. However, massive scale property has been damaged due to frequent fire accidents in ESS, which is installed and operated on site, and it is reported that most of the fire accidents are occurred during the rest time after full charging. In particular, since Li-ion batteries for ESS are composed of a combination of numerous cells in series and parallel, self-energy balancing phenomenon can be occurred, which current flows from a cell with a high SOC to a cell with a low SOC when the SOC states of cells connected in parallel are different due to deterioration, and the phenomenon is estimated to be one of the causes of the fire accidents. Therefore, this paper proposes a novel circuit configuration and operation algorithm of BMS to prevent self-energy balancing phenomenon in ESS. And also, this paper presents a modeling of self-energy balancing in Li-ion battery using PSCAD/EMTDC and implements a BMS composed of a battery unit, a charger unit, and a self-energy balancing unit, etc., using Labview S/W based on the proposed modeling. From the simulation and test results based on the proposed modeling and test device, it is found that aged cells may be adversely affected by the self-energy balancing phenomenon, and it is confirmed that the proposed BMS is useful tool to prevent self-energy balancing current for the safety of Li-ion battery.