FRACTIONAL MODELLING AND IDENTIFICATION OF A THERMAL PROCESS

Heat transfer problems obey to diffusion phenomenon. They can be modelled with the help of fractional systems. The simulation of these particular systems is based on a fractional integrator where the non integer behaviour acts only on a limited spectral band. A first model, based on the use of one fractional integrator, has been already defined and tested on a thermal pilot. Starting from frequency considerations derived from the analysis of a diffusion problem, a more general approximation of the fractional system is proposed in this communication. The new model is based on the use of two fractional integrator operators. It makes it possible to define a state-space model for simulation of transients, and to carry out an output-error technique in order to estimate the parameters of the model. Experimental results obtained on a thermal process illustrate the improvements obtained with the proposed model.