State of Energy Estimation of Lithium-Ion Capacitor for Rail Transit Application

Using activated carbon (AC) with nano- lithium iron phosphate (LiFePO
₄
) as the positive and hard carbon (HC) as the negative, this type lithium-ion capacitor (LIC) has the inherent advantages in rate characteristics, cycle life and chemical stability, which is more suitable for rail transit application. As an indicator of capacitor available energy, state of energy (SOE) is of great importance to estimate. However, most of the models utilized in the literature concerning state estimation of LIC become problematic for outlining the characteristics without considering wide current magnification. In this work, a method, which is considering wide current magnification, is proposed for state of energy estimation of LIC.