Mobile QR Code QR CODE : The Korean Institute of Power Electronics
Title Real-time OCV Curve and Capacity Estimation Algorithm for Reusable Battery in ESS Application
Authors Jong-Hun Lim ; Je-Yeong Lim ; Dong-Hwan Kim ; Byoung-Kuk Lee
Page pp.306-314
ISSN 1229-2214
Keywords Energy storage system; EVs retired battery; OCV curve; Secondary usage
Abstract This study proposes an algorithm that can estimate the open circuit voltage (OCV) in real time and form an OCV curve with gradual capacity updating. The proposed algorithm can gradually estimate the OCV curve and capacity of reusable batteries using the first RC ladder equivalent circuit model through linear regression and the Coulomb counting method. The combination of two time series data can create partial OCV curves in the operation region, which are unsorted fragments with a noise-sensing element. Therefore, the proposed algorithm can construct OCV curves through empirical mode decomposition and min-max curve scaling with sorting methods to gradually form the OCV curves in the upper and lower voltage ranges in the operating section. This study demonstrates the feasibility of the proposed algorithm through an energy storage system profile experiment on a 24.9 Ah aging lithium polymer battery. The curve estimation error is 2.3% in the final cycle.