Modelling for the effective control of the electric flow heaters – Simulation validation

This paper suggests the possibility of improving the performance of the control system for electric flow heaters by applying the balance-based adaptive control (B-BAC) methodology, in which the synthesis of the control law is always preceded by the nonstationary balance-based modelling according to the general but also strictly defined rules. The resulting simplified model of a heater is derived assuming a large uncertainty on the process nonlinearities and it has the form of the first-order dynamic equation with the only one time-varying parameter that represents the unknown nonlinearities and modelling inaccuracies. The value of this parameter is unknown so we suggest its on-line estimation by the weighted recursive least-squares (WRLS) method. The modelling accuracy is investigated by the simulation in the application to the example nonlinear electric flow heater. It is also shown how to derive the B-BAController on the basis of the suggested model. The generality of the simplified model ensures that the B-BAC methodology can be applied to control a wide variety of electric flow heaters and its application results in more effective control system, which is also verified by simulation in the comparison to the conventional PI controller.