Frequency Domain Effects of Constant Terms in Nonlinear Models

When converting a time-domain model of a nonlinear system into the frequency domain to get nonlinear freqency response functions, any constant of dc term in the time-domain model can have a significant effect on the time-to frequency domain mapping. The constant term cannot therefore, simply be discarded as in the linear case. This paper investigates this effect and two new algorithms are derived to compute the frequency response functions for two classes of nonlinear models, the polynomial model and the rational model when a constant term is present. The results are illustrated using several examples.