Dissertation/Thesis Abstract

Linear Parameter Varying Controller for a Small Turboshaft Engine
by Spack, Jeffrey Michael, M.S., Northeastern University, 2011, 158; 1499478
Abstract (Summary)

Small turboshaft engine control systems are traditionally single input single output (SISO) and are designed utilizing classical control methods which require extensive gain schedules resulting in considerable tuning effort. In addition, this method assumes that a system that is stable at the linearized points will be stable in between the linearized points which may or may not be true. With a linear parameter varying (LPV) control system, the gain schedule is inherently built into the controller and the system is guaranteed to be stable between linearizing points as long as the plant depends affinely on a set of time varying parameters that are available as real time measurements and also vary along a fixed polytope. Another benefit of using an LPV controller in place of a classic SISO controller is that modern robust control techniques can be applied.

A model of a General Electric T700 turboshaft engine and baseline control system were developed in Simulink using a NASA paper written by Mark G. Ballin. The engine plant was linearized at engine core speed points between 76% and 100% at intervals of 2%. The LPV power turbine speed controller was developed using linearized plants derived from the Simulink model. The LPV controller was then compared to the baseline control system showing performance greater than or equal to the baseline controller with a single set of weighting functions. The referee transients used to determine a performance comparison included steps and ramps in power turbine speed reference, helicopter collective load disturbances and uncompensated helicopter rotor load disturbances.

This research shows that an LPV controller can be applied to a small turboshaft engine application. It is also shown that while the LPV controller is more complex that is should trade well against the traditional SISO methods based on tuning effort and performance.

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Indexing (document details)
Advisor: Sznaier, Mario
Commitee: Gutz, David, Shafai, Bahram
School: Northeastern University
Department: Electrical and Computer Engineering
School Location: United States -- Massachusetts
Source: MAI 50/02M, Masters Abstracts International
Subjects: Mechanical engineering
Keywords: Engine control, Linear parameter varying
Publication Number: 1499478
ISBN: 978-1-124-87522-4
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