Nondiagonal QFT Controller Design for a Three-Input Three-Output Industrial Furnace

Abstract

This paper addresses the temperature control of a three-input (power supplies) three-output (temperature sensors) industrial furnace used to manufacture large composite pieces. Due to the multivariable condition of the process, the strong interaction between the three control loops and the presence of model uncertainties, a sequential design methodology based on quantitative feedback theory is proposed to design the controllers. The methodology derives a full matrix compensator that improves reliability, stability, and control. It not only copes with furnace model uncertainties but also enhances the reference tracking and the homogeneousness of the composite piece temperature while minimizing the coupling effects among the furnace zones and the operating costs.