State of health estimation and error reduction method for embedded lithium battery system

초록

Recently, as fossil fuel use is regulated in many countries for carbon neutrality, the use of lithium-ion batteries has been gradually increasing. Therefore, estimating the state of health (SOH) of lithium-ion batteries has become increasingly important to check the life of the battery and ensure safe usage. Among them, the SOH of industrial ESS (Energy Storage System) requires accurate SOH results without errors, rather than real-time calculations. For this reason, ESS typically updates the SOH of lithium battery systems once or twice a year to improve the accuracy of SOH estimation of lithium-ion batteries. Full charging and full discharging are inconvenient because they must be performed manually by the user, and can be dangerous in unmanned systems, as they can lead to overcharging and overdischarging. Additionally, a simple and automatically calculated SOH algorithm is required so that it can be installed in lithium battery embedded systems. To address this issue, we developed a method for calculating SOH suitable for ESS environments, and added logic to reduce errors that may occur. Without the error reduction logic, the test results showed an error of 6.28 %, but with the error reduction logic, the error was reduced to less than 3 %. In this paper, we present a method for calculating the SOH of ESS and an error reduction logic. This method can improve product reliability by reducing the possibility of errors and increasing the accuracy of SOH calculations.

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