Energy- and phase-frequency characteristics of nonlinear systems

The frequency response approach is a powerful tool for the analysis and design of linear systems. To represent the behaviour of nonlinear systems the method of energy- and phase-frequency characteristics (EPFC) has been developed. This method is applied successfully to an automated modelling process of a software tool for hydraulic circuit simulation, already. Owing to the system-theoretical character of the approach, however, it is not bound to this special application. The method establishes a consistent extension of frequency response to static and dynamic nonlinear systems. Its graphical representation leans on the Bode diagram. This article presents an overview of the basic ideas, the calculation and an example for the application of the EPFC. Moreover, it points out objectives of further research work.