Application of Parameter Extraction Techniques for Impedance Spectroscopy

The more effects and mechanisms are represented in an impedance spectrum, the more unknown parameters are needed for an accurate modeling. The parameter extraction process becomes thereby more difficult to solve and needs a lot of trials and a priori knowledge. Some sophisticated optimization techniques were investigated at models with different complexity levels in order to increase efficiency during this process. For simple models evolution strategy seems to be nearly insensitive to the chosen search region. For models with a large number of unknown parameters, a combination of evolution strategy with the Levenberg-Marquardt (LevMq) method reaches very good results compared with each method alone. This hybrid solution profited also from different sensitivities of both methods and allowed a better handling of difficult inverse identification problems. The resulting process is robust and reaches good modeling results even, if only a few a priori knowledge is available concerning expected parameter values