Rapid State-of-Power Estimation of Lithium-Ion Batteries in DC Microgrids

Abstract

Lithium-ion batteries are widely used as energy storage systems in DC microgrids. These batteries operate alongside various types of energy sources and loads connected to the grid. Therefore, monitoring the battery's state is essential to ensure efficient and safe operation. To protect the battery from unsuitable conditions, such as overvoltage or overcharge, it is crucial to monitor the battery's state-of-power (SOP). SOP estimation is typically conducted using state observers to analyze the dynamic behavior of the battery. An alternative, faster method for assessing battery dynamics involves rapid measuring of the internal impedance of the battery. Recent studies have demonstrated that broadband methods can provide fast and accurate battery impedance measurements. This paper presents a rapid SOP estimation method that utilizes broadband-measured battery-impedance and a fast impedance modeling method to evaluate the battery cell's terminal voltage. The method is tested experimentally on commercial battery cells to validate its accuracy and efficiency.