Interconnected Observers for online supercapacitor ageing monitoring

To observe the state of health of supercapacitors, offline laboratory techniques such as Electrochemical Impedance Spectroscopy (EIS) are regularly used. But this requires the supercapacitors to be removed from their application. This paper proposes an online in situ monitoring method based on the estimation of the supercapacitor parameters by means of real-time observers. Two kinds of observers, an Extended Kalman Observer (EKO) and Interconnected Observers (IOs), are designed and compared. Identification results are presented for real 1F Nichicon supercapacitors enduring an accelerated ageing process, and compared with the offline characterization.