Disturbance-rejection-oriented temperature control of shrink tunnels under varying grid voltage

This paper addresses the design of temperature controllers for shrink tunnels, which are machines composed of an industrial oven and a conveyor belt employed for packaging purposes. Specifically, the present work focuses on the rejection of disturbances arising from two sources: (i) the flow of products inserted into the oven by the conveyor belt, which causes abrupt temperature drops, and (ii) the varying grid voltage, which perturbs the heat generated by the heat resistors commanded by the regulator. To that end, a recent control architecture is extended with the addition of (i) feedforward compensators and (ii) a suitable rescaling strategy for the control actions, effectively addressing the previously mentioned disturbances. The performances of the proposed strategy are validated on an experimental workbench, showing improved disturbance rejection capabilities compared to the baseline approach.