Integral Terminal Sliding Mode with Automatic Gain Tuning Fuzzy Logic Controller to Regulate Evaporator Superheat Temperature in HVAC Systems

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Date

2024-10

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Publisher

Addis Ababa University

Abstract

HVAC systems are inherently complex, and this complexity, along with various disturbances, makes it challenging to control the system effectively. Achieving a balance between meeting strict comfort requirements and minimizing energy use for optimal performance is particularly difficult. This thesis introduces a combined control strategy: the Integrated Terminal Sliding Mode Controller with Automatic Gain Tuning and Fuzzy Logic (ITSMCFLAG). This controller regulates the superheat temperature at the evaporator outlet by adjusting the opening of the electronic expansion valve (EEV). The ITSMC-FLAG controller efficiently manages both the evaporator superheat and evaporating temperature by adjusting the expansion valve’s opening based on the superheat at the evaporator outlet and the inlet mass flow rates. It also takes into account the return room temperature and environmental uncertainties. This advanced approach not only enhances cooling performance and reduces energy consumption, but it also extends the lifespan of the compressor. By combining terminal sliding mode control with fuzzy logic, the ITSMC-FLAG controller improves HVAC performance through a dynamic fuzzy logic auto-gain mechanism that adjusts the system’s gains according to the current operating conditions. This ensures consistent and optimal performance, even with disturbances and fluctuations in system dynamics. Comprehensive MATLAB simulations demonstrate the significant potential of the proposed controller to improve cooling efficiency, reduce energy consumption, and extend compressor life.

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Keywords

HVAC system, Integrated Terminal Sliding Mode, Automatic Gain Tuning, Fuzzy Logic Controller, Evaporator Outlet Superheat, Evaporating Temperature, Electronic Expansion Valve

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