Robust Control of Transport Refrigeration System

Kovacevic, Ajdin

4. term

Control and Automation, Master

2020

2020-01-08

98 pages

The purpose of this project is to design a robust controller that can handle the dynamic changes in which appears when ice builds up on the evaporator coil. To be able to design such a controller, a model from the company is used. The model is initially a MIMO model of 14 states, 4 inputs and 2 outputs. But to make the controller design simple, it is decided to decouple the MIMO into two SISO systems. The chosen robust controller is a H$_\infty$ controller and the main goal is to have a stable superheat while ice builds up on the evaporator coil. To design a H$_\infty$ controller some requirements needs to be achieved. These requirements are made for the nominal stability, nominal performance, robust stability and robust performance, which can be achieved by designing weight functions that fits with the conditions. The H$_\infty$ controller is designed as a PID controller and through simulations it is proven to be functional. While it might be functional theoretically. When it is implemented on the real system, it has proven to be difficult to be nominal stable. All in all this project has proven that the solution, to the ice appearance on the evaporator coil issue, might not be a robust control, which therefore gives opportunity to investigate other solutions to this problem.

Master Thesis

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