Comparative Analysis of Some Parametric Model Structures Dedicated to EDLC Diagnosis

Abstract

Electrical double-layer capacitors (EDLCs) are now widely used as power buffers in energy storage systems, especially for electrical transport applications. Because of their high acquisition costs, their predictive maintenance represents a key issue for the development of electrical traction systems. This paper investigates the diagnosis of EDLCs by a parametric estimation of a dynamic continuous-time model. Indeed, the physical interpretation of their parameters simplifies the supercapacitor diagnosis and prognosis. Due to the complex electrochemical phenomena occurring in EDLC cells, modeling errors are far more important than measurement noise. Therefore, we propose to use the output error minimization techniques and the relative sensitivity functions to evaluate and compare the diagnosis potential of several model structures. This allows the use of some comprehensive comparison criteria without any assumption about the statistical characteristics of the system disturbances. An experimental accelerated aging process of 200 commercial super capacitors (Nichicon, 1F, 20 weeks long aging at 65 °C, 0 and 2.5 V dc polarization) is also performed to make statistics and illustrate the methodology.