Robust stability of thermal control systems with uncertain parameters: The graphical analysis examples

• Published in: Applied thermal engineering Vol. 125; pp. 1157 - 1163
• Main Authors: Matušu, Radek, Pekar, Libor
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.10.2017; Elsevier BV
• Subjects: Analysis; Control stability; Control systems; Delay; Feedback control; Feedback control systems; Fractional order systems; Heat exchangers; Heat transfer; Mathematical models; Parameter uncertainty; Parametric uncertainty; Robust control; Robust stability analysis; Robustness (mathematics); Stability analysis; Thermal control systems; Thermal systems; Time delay; Tube heat exchangers; Uncertainty; Uncertainty analysis; Fractional order systems; Thermal systems; Time delay; Parametric uncertainty; Robust stability analysis
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2017.07.089

•A method for robust stability analysis of thermal control systems is presented.•The graphical method is applicable for various systems with parametric uncertainty.•The technique is extremely universal and relatively easy to use.•Even very complicated systems (with non-existing analytical tools) can be analyzed.•The robust stability is investigated with the necessary and sufficient condition. This paper is intended to present the investigation of robust stability for integer order or fractional order feedback control loops affected by parametric uncertainty and time-delay(s) with special emphasis on the thermal control systems. The applied graphical method is based on the numerical calculations of the value sets and the zero exclusion condition. Three robust stability examples inspired by control of the real-world thermal processes are used for demonstration of the technique applicability. Namely, the work deals with the analysis of a shell-and-tube heat exchanger which was identified as the (integer order) time-delay model with parametric uncertainty, a heat transfer process modeled as the fractional order time-delay plant with parametric uncertainty, and a heating–cooling system with a heat exchanger described by the anisochronic model with internal delays and parametric uncertainty.