Conference article

Superheat Control with a Dynamic Inverse Model

Andreas Varchmin
Technische Universität Braunschweig, Institut für Thermodynamik, Germany

Manuel Gräber
TLK-Thermo GmbH, Germany

Wilhelm Tegethoff
Technische Universität Braunschweig, Institut für Thermodynamik, Germany/TLK-Thermo GmbH, Germany

Jürgen Köhler
Technische Universität Braunschweig, Institut für Thermodynamik, Germany

Download articlehttp://dx.doi.org/10.3384/ecp14096867

Published in: Proceedings of the 10th International Modelica Conference; March 10-12; 2014; Lund; Sweden

Linköping Electronic Conference Proceedings 96:90, p. 867-873

Show more +

Published: 2014-03-10

ISBN: 978-91-7519-380-9

ISSN: 1650-3686 (print), 1650-3740 (online)

Abstract

Superheat control has influence on the coefficient of performance (COP); the stability and the compressor endurance of a vapor compression cycle. In an increasing number of applications electronic expansion valves are used. This leads to more complex control tasks. It raises the question if simulation models can be used for feedforward control to fulfill this function. For building a feedforward control structure a simulation model needs to be inverted. In this paper a submodel of a refrigeration cycle; consisting of models for expansion valve and evaporator; is inverted. The resulting controller is tested in a model-in-the-loop environment and applied on an automotive refrigeration cycle. The advantage of a dynamic inverse model in contrast to a static one is pointed out. Also the results are compared to a standard PI controller.

Keywords

Inverse models; superheat control; vapor compression cycles; feedforward control

References

[1] Y. Chen, S. Deng, X. Xu and M. Chan. A study on the operational stability of a refrigeration system having a variable speed compressor. International Journal of Refrigeration, 31(8):1368-1374, May 2008.

[2] W. Chen, Z. Chen, R. Zhu and Y. Wu. Experimental investigation of a minimum stable superheat control system of an evaporator. International Journal of Refrigeration, 25(8):1137-1142, December 2002.

[3] K.J. Åström and T. Hägglund. Advanced PID Control. Instrumentation, Systems and Automation Society, USA, August 2005.

[4] G. Looye, M. Thümmel, M. Kurze, M. Otter, J. Bals. Nonlinear Inverse Models for Control. In: Proceedings of the 4th International Modelica Conference, Hamburg, Germany, 2005.

[5] C. Richter. Proposal of New Object-Oriented Equation-Based Model Libraries for Thermodynamic Systems. PhD thesis, Technische Universität Braunschweig, 2008.

[6] C. Schulze. A Contribution to Numerically Efficient Modelling of Thermodynamic Systems. PhD thesis, Technische Universität Braunschweig, 2013.

[7] M. Gräber, K. Kosowski, C. Richter, W. Tegethoff. Modelling of Heat Pumps with an Object-Oriented Model Library for Thermodynamic Systems. Mathematical and Computer Modelling of Dynamical Systems, Taylor & Francis, October 2010.

[8] T. Hägglund, K.J. Åström. Revisiting the Ziegler-Nichols rules for PI control. Asian Journal of Control, 4(4):364-380, 2002.

Citations in Crossref