Projeto do sistema de controle de uma plataforma experimental para caracterização de sensores termo-resistivos.

Abstract

This work studies the design of the control system of an experimental platform based on a Peltier device that is employed a heat pump. Such platform has been developed to simplify the characterization of thermo-resistive sensors by providing controlled heating and cooling of the device under test through the control of the value and the rate of change of the Peltier supply current. The Peltier device exhibits a non-linear behavior and thus in order to design the control system of the platform (thermal chamber, Peltier module and heat-sink) i t is required to study a non-linear model derived from thermodynamic heat exchange equations. The proposed modeling approach is based on an input/output model in which parametric identification techniques are employed to find the values of the parameters of a discrete-time model. The identification experiments were carried out for an operating region where the Peltier supply current varies from [—3, +3]A in steps of 0.5A The parameters of the discret-time model were obtained for such operating region via polynomial interpolation. Based on such non-linear discrete-time model control laws to track different temperature reference profiles can designed. Pole placement technique was employed in the controller design. Consequently, to provide the same transient and dynamic performance in closed-loop, the control law must also vary with the Peltier supply current. The experimental results obtained with a laboratory prototype demonstrate the feasibility of the proposed test platform.