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Many model based control methods exist in the literature. Producing a sufficient system model can be cumbersome and a new non-model based method for control of nonlinear systems with input/output maps exhibiting sigmoid function properties is therefore proposed. The method utilizes an excitation signal together with Fourier analysis to generate a feedback(More)
An important aspect of efficient and safe operation of refrigeration and air conditioning systems is superheat control for evaporators. This is conventionally controlled with a pressure sensor, a temperature sensor, an expansion valve and Proportional-Integral (PI) controllers or more advanced model based control. In this paper we show that superheat can be(More)
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This paper presents a challenging industrial benchmark for implementation of control strategies under realistic working conditions. The developed control strategies should perform in a plug & play manner, i.e. adapt to varying working conditions, optimize their performance, and provide fault tolerance. A fault tolerant strategy is needed to deal with a(More)
Maintaining foodstuff within predefined temperature thresholds is important due to legislative requirements and to sustain high foodstuff quality. This is achieved using a refrigeration system. However, these systems might not be dimensioned for hot summer days or possible component performance degradation. A learning based algorithm is proposed in this(More)
Evaporator Superheat Maximum slope-seeking Harmonics Control a b s t r a c t Superheating of refrigerant in the evaporator is an important aspect of safe operation of refrigeration systems. The level of superheat is typically controlled by adjusting the flow of refrigerant using an electronic expansion valve, where the superheat is calculated using(More)
— Refrigeration is important to sustain high foodstuff quality and lifetime. Keeping the foodstuff within temperature thresholds in supermarkets is also important due to legislative requirements. Failure to do so can result in discarded foodstuff, a penalty fine to the shop owner, and health issues. However, the refrigeration system might not be dimensioned(More)