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Research Papers

Design and Implementation of a Digital Multimode H Controller for the Spey Turbofan Engine

[+] Author and Article Information
Raza Samar1

Department of Electronic Engineering, Mohammad Ali Jinnah University, Islamabad 44000, Pakistanrsamar@jinnah.edu.pk

Ian Postlethwaite

Control and Instrumentation Research, Department of Engineering, University of Leicester, Leicester LE1 7RH, UKixp@le.ac.uk

1

Corresponding author.

J. Dyn. Sys., Meas., Control 132(1), 011010 (Dec 17, 2009) (11 pages) doi:10.1115/1.4000656 History: Received July 04, 2008; Revised October 06, 2009; Published December 17, 2009; Online December 17, 2009

In this paper, a 2 degrees-of-freedom multimode controller design for the Rolls Royce Spey turbofan engine is presented. The controller is designed via discrete time H-optimization; it provides robust stability against coprime factor uncertainty, and a degree of robust performance in the sense of making the closed-loop system match a prespecified reference model. Multimode control logic is developed to preserve structural integrity of the engine by limiting engine variables to specified safe values. A simple strategy for antiwindup and bumpless transfer between controllers, based on the Hanus anti-windup scheme (1987, “Conditioning Technique, A General Anti-Windup and Bumpless Transfer Method,” Automatica, 23(6), pp. 729–739) and the observer-based structure of the controller, is presented. The structure of the overall switched controller is described. Actual engine test results using the Spey engine test facility at Pyestock are presented. The controller is shown to perform a variety of tasks, its multimode operation is illustrated and improvements offered on existing engine control systems are discussed.

Copyright © 2010 by American Society of Mechanical Engineers
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Figures

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Figure 1

The Rolls Royce Spey engine test facility (courtesy of QinetiQ, Pyestock)

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Figure 2

Illustration of the switching scheme

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Figure 3

2DOF design configuration with left coprime factor perturbation on the plant

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Figure 4

Controller structure used for implementation

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Figure 5

The shaped plant and the controller

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Figure 6

Singular values of the shaped plant for the PS6PS1 controller design

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Figure 7

Reference step responses for the PS6PS1 controller (PS6PS1 indicated by a solid line, DPUP indicated by a dashed line, NHPCSL indicated by a dashdot line, and NL indicated by a dotted line)

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Figure 8

Sensitivity function (I+GW1K2W2)−1 for the PS6PS1 controller

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Figure 9

Sensitivity function (I+GW1K2W2)−1 for the TT15 limiter

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Figure 10

Structure of the overall switched controller

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Figure 11

Reference tracking for the controlled outputs: idle to maximum power (commanded value indicated by a dashed line and actual output indicated by a solid line). (a) Reference tracking for PS6PS1, (b) reference tracking for DPUP, (c) reference tracking for NHPCSL, and (d) engine thrust (kN) measurement.

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Figure 12

Actuator (control) signals: idle to maximum power. (a) Fuel flow (cc/s), (b) nozzle area (%), (c) guide vane angle (deg), and (d) blow-off valve position (%).

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Figure 13

Reference tracking for the controlled outputs: maximum power to idle (commanded value indicated by a dashed line and actual output indicated by a solid line). (a) Reference tracking for PS6PS1, (b) reference tracking for DPUP, (c) reference tracking for NHPCSL, and (d) engine thrust (kN) measurement.

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Figure 14

Actuator (control) signals: maximum power to idle. (a) Fuel flow (cc/s), (b) nozzle area (%), (c) guide vane angle (deg), and (d) blow-off valve position (%).

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Figure 15

Switching from the PS6PS1 controller to the NL limiter by lowering the limit: (commanded value indicated by a dashed line and actual output indicated by a solid line) (a) reference tracking for PS6PS1, (b) reference tracking for DPUP, and (c) reference tracking for NHPCSL; and (NL limit indicated by a dashed line and NL indicated by a solid line) (d) NL limiting: lowering the limit

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Figure 16

Actuator signals: switching to the NL limiter by lowering the limit. Fuel outputs (PS6PS1 controller indicated by a dotted line, NL limiter indicated by a dashdot line, and fuel selected (to engine) indicated by a solid line): (a) fuel selection: lowest wins, (b) nozzle area (%), (c) guide vane angle (deg), and (d) blow-off valve position (%).

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Figure 17

Switching from the PS6PS1 controller to the NL limiter due to excessive PS6PS1 demand: (commanded value indicated by a dashed line and actual output indicated by a solid line) (a) reference tracking for PS6PS1, (b) reference tracking for DPUP, and (c) reference tracking for NHPCSL; and (NL limit indicated by a dashed line and NL indicated by a solid line) (d) riding up to and holding NL limit

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Figure 18

Actuator signals: switching to the NL limiter due to excessive PS6PS1 demand. Fuel outputs (PS6PS1 controller indicated by a dotted line, NL limiter indicated by a dashdot line, and fuel selected (to engine) indicated by a solid line): (a) fuel selection: lowest wins, (b) nozzle area (%), (c) guide vane angle (deg), and (d) blow-off valve position (%).

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Figure 19

Switching from the PS6PS1 controller to the TT15 limiter due to excessive PS6PS1 demand: (commanded value indicated by a dashed line and actual output indicated by a solid line) (a) reference tracking for PS6PS1, (b) reference tracking for DPUP, and (c) reference tracking for NHPCSL; and (TT15 limit indicated by a dashed line and TT15 indicated by a solid line) (d) riding up to and holding TT limit

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Figure 20

Actuator signals: switching to the TT15 limiter due to excessive PS6PS1 demand. Fuel outputs (PS6PS1 controller indicated by a dotted line, TT15 limiter indicated by a dashdot line, and fuel selected (to engine) indicated by a solid line): (a) fuel selection: lowest wins, (b) nozzle area (%), (c) guide vane angle (deg), and (d) blow-off valve position (%).

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