A hierarchical control strategy for aircraft thermal systems

Williams, Matthew A.

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https://hdl.handle.net/2142/50649 Copy

Description

Title

A hierarchical control strategy for aircraft thermal systems

Author(s)

Williams, Matthew A.

Issue Date

2014-09-16

Director of Research (if dissertation) or Advisor (if thesis)

Alleyne, Andrew G.

Department of Study

Mechanical Sci & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Modeling and Control
• Large-scale systems
• Aircraft thermal systems
• Model predictive control
• Optimization
• Thermal energy

Abstract

Aircraft systems present an interesting control problem given the fact that there exist multiple objectives, actuators, and physical dependencies throughout the system. For decades the onboard systems of aircraft have worked in isolation seeking to achieve their goals while giving little to no consideration to actions or constraints of other systems. As aircraft become more electric, aircraft systems can no longer work in isolation without regard to the constraints and limitations of other systems. Current generation aircraft are experiencing complications between electrical and thermal management systems that have emerged as a result of the increasing prevalence of electrical systems onboard aircraft. Due to these trends, new strategies for controlling aircraft systems are required so that decision making and communication can occur between the vehicle, system, subsystem, and component levels of an aircraft. This thesis looks at establishing the groundwork for the development of next-generation control for aircraft systems. Since testing aircraft systems would be a costly endeavor, models of an aircraft’s electrical, thermal, hydraulic, and pneumatic systems are developed for computer based simulation. A five-level hierarchical control strategy is proposed that seeks to minimize objectives at the vehicle, system, subsystem, component, and physical level. This thesis looks specifically at the system and subsystem-levels of the hierarchy while focusing on the thermal system of the aircraft. At the system level a model predictive controller is developed for minimizing total energy consumption while maintaining the temperature of thermal zones within some bounds. Control decisions made by the system-level controller are passed to a subsystem controller that is formulated as a mixed integer quadratic programming problem which seeks to minimize power consumption while meeting the command of the system-level controller. The subsystem-level controller is responsible for determining the optimal operational mode for each thermal subsystem. An example system consisting of a passenger cabin, fuel tank, vapor compression system, air cycle machine, and ram air cooling loop is used to demonstrate the capabilities of the proposed system and subsystem-level controllers. Controller parameters are analyzed to determine the effect on total power consumption and temperature regulation. Preliminary results show that the two-level hierarchical controller is capable of maintaining temperatures within constraints while minimizing total power consumption.

Graduation Semester

2014-08

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http://hdl.handle.net/2142/50649

Copyright and License Information

Copyright 2014 Matthew A. Williams

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