Stability of Subharmonic Oscillations in Nonlinear Systems

Abstract

This paper presents a method for finding necessary conditions such that a subharmonic oscillation may exist in certain types of nonlinear feedback systems. The method is applicable to feedback systems with one, instantaneous, nonmemory-type, nonlinear element. Equations are derived giving the fundamental output of a nonlinear element when forced by two sine waves of integer ratio frequency. Normal describing-function assumptions are made with regard to attenuation of higher-order harmonics. An example of a system incorporating a perfect relay is presented. The results of the analysis have been verified experimentally on the analog computer.