ELECTRICAL MODELING OF DOUBLE LAYER CAPACITOR

The recent energy crisis has made saving energy increasingly important. The growing interest in energy storage has lead to the study of new technologies capable of satisfy the market requests. Supercapacitors currently seem to be interesting devices for many applications because of their characteristics. Supercapacitors are electrical energy storage devices that offer high power density and a high number of charge and discharge cycles. Their nominal storable energy is always lower than electrochemical batteries, however they can offer many advantages in several industrial applications. This chapter initially will describe supercapacitor models to characterize the electrical behaviour of Double Layer Capacitors (DLCs) according to different applications and finally a new innovative model, named the two-branch dynamic model. This new model, from a circuit point of view, is similar to others in literature (e.g. three-branch model and series model), but there are three main differences. The first and the second one are due to the easier and faster parameters identification process, and the reduced number of parameters, while the last one is related to the ability to represent a wide working frequency range, that permits to characterize correctly the supercapacitors electrical behaviour in their typical working conditions. The parameters’ identification procedure will be described for the proposed model. Moreover the model will be investigated in order to determine the application limits according to the charge and discharge frequency. Experimental charge and fast charge-discharge tests have been carried out on different supercapacitor sizes of two different makers in order to validate the proposed model.