가변속 냉동시스템의 견실 온도 제어를 위한 구조화 불확실성 기반의 μ-Synthesis 제어기 설계

Abstract

This paper investigates μ-synthesis robust control for a variable speed refrigeration system to enhance robustness against model uncertainty and external disturbance. As the practical transfer function model obtained by experiments to design a controller inevitably contains model uncertainties such as unmodeled dynamics and modeling errors, a robust controller is necessary to track references in the system. Target temperature and superheat were simultaneously controlled in the system by adjusting rotating speed of compressor and opening angle of an electronic expansion valve respectively. Moreover, the μ-synthesis controller treats model uncertainty as structured perturbation; it is designed using structured singular value. It is shown that the μ-synthesis approach which takes structured uncertainties into account provides robust control performance against both dynamic perturbations including modeling errors and external disturbances. The validity of the proposed method was demonstrated by simulations and experiments.