Online Supercapacitor Diagnosis for Electric Vehicle Applications

Abstract

This paper presents an online diagnosis method for supercapacitors' aging problem. State-of-Health (SoH) estimation is an important feature since aging introduces degradation in supercapacitors' performance, which might eventually lead to their failure. SoH is usually measured by Electrochemical Impedance Spectroscopy (EIS). But, this has to be performed offline and requires interruption of the system's operation. Unlike this method, this paper presents an online diagnosis technique for supercapacitors using an extended Kalman observer as a well-known tool for its particularities and performances to study nonlinear parameters estimation. The main objective of this paper is the online State-of-Health diagnosis based on the supercapacitors aging indicators estimation. Moreover, the proposed online estimation strategy requires only voltage and current measurements, which reduces the number of sensors with respect to other methods. The effectiveness of the proposed online observer is shown through experimental results and robustness to noise is also studied. S 0018-9545 (c)

A Driving-Behavior-Based SoC Prediction Method for Light Urban Vehicles Powered by Supercapacitors

“…Here, we derive formulas (18) and (19) Rearranging (21) and (22) into (23) and then multiplying both sides by the derivative of () c Ut, we obtain the first-order, second-degree differential equation (24). ( ) ( ) ( )…”

“…In addition, if a driver knows the remaining SoC in the future when the driver reaches the destination, they can drive with relatively less stress. Although an accurate prediction of the SoC is crucial for EV onboard applications, to the best of the authors' knowledge, no studies have focused on SoC prediction techniques, which is a relatively newer field of study compared with SoC estimation [19,20], State of Health (SOH) determination [21,22] and State of Power (SOP) prediction [23].…”

Supercapacitors State-of-Health Diagnosis for Electric Vehicle Applications

“…They are two test types: "DC voltage test" and "voltage cycling test". Calendar life testing is often mentioned in the literature [12]. The cells are prepared in different states of discharge (SOD) and are subjected to different temperatures.…”

“…The RC circuit parameters have been determined offline based on the impedance measurements at different operating temperatures. On the other hand, El Mejdoubi et al [12] present an online supercapacitors state-of-health diagnosis using the extended Kalman observer to estimate the aging indicators, the resistance and the capacitance, whatever the operating temperature and the charging current profile. The contribution of this paper is to propose an online SoH diagnosis technique for supercapacitors.…”

Establishment of an Online Design for Failure Diagnosis through Simulation of the Equivalent Model of LiMn2O4 Battery

“…The proper operation of batteries must be ensured when working. To realize this goal, we need a prevention or diagnosis feature in the BMS for the operation of EVs [8].…”