Commercial supercapacitor parameter estimation from step voltage excitation

Supercapacitors are crucial elements in advanced industrial electronic systems particularly when supplied from renewable energy sources. Here, we derive expressions for the current, power, and stored energy in a supercapacitor excited with a step voltage signal. Although, it is not common practice to charge supercapacitors using a step voltage, these devices are sometimes used in switching-type applications where they are subject to this type of signal. We validate the derived mathematical expression of the current via experiments on four different commercial devices. By fitting the measured current data to the derived expression, the parameters of these devices, which are modeled as a series connection of an internal resistance and a constant phase element (CPE), are also estimated. Power and energy are then evaluated followed by the estimation of the effective capacitance for each device. Our analysis makes use of fractional order calculus as opposed to classical integer-order models. © 2019 John Wiley & Sons, Ltd.