Theoretaical Analysis of Self-discharge behavior of Supercapacitor using physical parameter variation in Simulink/ MATLAB

Abstract

Understanding the self-discharge behavior of a supercapacitor is very important regarding make it more efficient for its applications. Different types of RC circuit models have been developed. We have studied the different RC circuit models and took the classical RC circuit model to study self-discharge behavior. This model requires three parameters: a capacitor (Cs), parallel resistance (R), and equivalent series resistance (R_esr), and very easy to implement in simulation. The simulation has been done using Simulink/MATLAB. The effects of the initial voltage, temperature, charge duration and capacitance on the self-discharge of supercapacitors have been presented in this paper. The procedure of self-discharge measurement is as follows: Firstly, the supercapacitor is fully charged at a fixed voltage and then the supercapacitor is left to discharge by itself in an open circuit and then voltage drop across the supercapacitor is measured. It has been observed that higher the initial voltage, higher the rate of self-discharge. The effect of temperature has simulated at different temperatures by varying the value of equivalent series resistance and it is observed that as the temperature increases, the self-discharge rate also increases. In effect of charge duration, we have observed that self-discharge is maximum in short duration of charging and minimum in longer duration of charging. In effect of capacitance, we observed that self-discharge is independent of capacitance.