DISCRETE TRANSCENDENT TRANSFER FUNCTION AND ITS APPROXIMATION

KUKAL, J.; SCHMIDT, O.

Abstract

Linear systems with distributed parameters are described via linear partial differential equations. The application of Laplace transform comes to discrete transcendent transfer function. When the response to unit step is aperiodic then the transfer function can be approximated by the system of second order with time delay. Using the sampler of zero order with given period we obtain adequate discrete transfer function. In the case of large sampling period the second order approximation with time delay has higher accuracy then in the case of short sampling period. The role of sampling is studied on three examples of heat and mass transfer systems. The models include heat transfer in spherical region, mass transfer in thin layer and axial dispersion in tube reactor. The methodology is based on inverse Laplace transform, sampling, Z transform and properties of power series. All the calculations were made in the Matlab environment.

Coresponding author e-mail: Jaromir[dot]Kukal[at]vscht[dot]cz

Session: Algorithms and Computing for Control