On adaptive Control of Thermsl Processes by a Predictive 3-Level-Controller

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Due to the progress in the field of digital computers and computing techniques, today more and more control strategies which require a high computational effort get the chance to be realized and tested in industrial applications. For the control of thermal processes, as can be found e.g. in the area of plastics processing, chemical engineering and thermal techniques, a concept for an adaptive predictive on-off control strategy has been developed and successfully tested. By means of a relay one actuating device, e.g. an electrical resistance heater, can be switched on or off. The control performance thus gained is comparable to that of conventional controllers.A broader application of this unconventional concept is to be expected from a predictive switching control strategy which can be used for thermal processes with two actuating devices, e.g. an electrical resi stance heater and a fan, as well. Basically such applications render possible predictive strategies for an adaptive 3-1evel-control. Caused by the use of two counteracting actuating devices, however, the identification of the thermal process, the estimation and updating of proper process models as well as the realization of a predictive control strategy turn out to require an effort which is clearly higher than with an on-off control concept. First investigations, however, show that the problems can be handled. A basic concept is described, first results from digital simulations make possible a rough evaluation. Possible improvements and necessary further developments are concluded.