Cascaded Multi-Variable Control System for a Turboshaft Engine

• US 20150113996A1
• Filed: 05/20/2014
• Published: 04/30/2015
• Est. Priority Date: 10/24/2013
• Status: Active Grant

• Current Assignee: Rtx Corporation
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Cai, Chaohong, Crowley, Timothy J., Meisner, Richard P.
• Granted Patent: US 10,113,487 B2
• Time in Patent Office: Days
• US Class Current: 60/773
• CPC Class Codes: F02C 9/28 Regulating systems responsive to plant or ambient parameters, e.g. temperature, pressure, rotor speed F02C9/30 - F02C9/38, F02C9/44 take precedence
• CPC Class Codes: F02C 9/54 by throttling the working fluid, by adjusting vanes
• CPC Class Codes: F05D 2220/329 in helicopters
• CPC Class Codes: F05D 2270/052 Torque

Abstract

A control system for a gas turbine engine is disclosed. The control system may include a computer processor. The control system may also include an outer loop control module programmed into the computer processor to determine a torque request based at least in part on a real-time collective lever angle command. The control system may also include an inner loop control module programmed into the computer processor to receive the torque request from the outer loop control module, to determine fuel flow and inlet guide vane schedules based at least in part on the received torque request, and to send signals to a gas generator of the gas turbine engine in order to control the gas generator according to the determined fuel flow and inlet guide vane schedules.

Claims

1. A control system for a gas turbine engine, comprising:

a computer processor;

an outer loop control module programmed into the computer processor to determine a torque request based at least in part on a real-time collective lever angle command; and

an inner loop control module programmed into the computer processor to receive the torque request from the outer loop control module, to determine fuel flow and inlet guide vane schedules based at least in part on the received torque request, and to send signals to a gas generator of the gas turbine engine in order to control the gas generator according to the determined fuel flow and inlet guide vane schedules.

2. The control system of claim 1, further comprising a load estimation module in communication with the outer loop control module, the inner loop control module, and the gas turbine engine, the load estimation module programmed to generate signals indicative of a real-time estimated power turbine speed and a real-time estimated power turbine torque.

3. The control system of claim 2, wherein the outer loop control module determines the torque request based at least in part on the real-time estimated power turbine speed and a desired power turbine speed.

4. The control system of claim 1, wherein the inner loop control module determines the fuel flow and inlet guide vane schedules based at least in part on the real-time estimated power turbine speed.

5. The control system of claim 1, wherein the outer loop control module determines the torque request based at least in part on operational inputs.

6. The control system of claim 1, wherein the outer loop control module includes inversion of a dynamic model of a rotor.

7. The control system of claim 1, wherein the inner loop control modules determines stability bleed schedules based at least in part on the received torque request, and sends a signal to the gas generator of the gas turbine engine in order to control the gas generator according to the determined stability bleed schedules.

8. The control system of claim 1, wherein the inner loop control module includes inversion of a dynamic model of a gas generator.

9. The control system of claim 8, wherein the dynamic model of the inner loop control module is constrained to limits of the gas turbine engine.

10. The control system of claim 9, wherein the inner loop control module determines the fuel flow and inlet guide vane schedules based at least in part on operational inputs.

11. A method for controlling a gas turbine engine, comprising:

a computer processor receiving a real-time collective lever angle command and a real-time power turbine speed signal;

the computer processor generating a torque request based at least in part on the real-time collective lever angle command and the real-time power turbine speed signal;

the computer processor generating a fuel flow signal and an inlet guide vane signal based at least in part on the generated torque request; and

the computer processor sending the fuel flow signal and the inlet guide vane signal to a gas generator of the gas turbine engine to control a power turbine torque of the gas turbine engine.

12. The method of claim 11, further comprising a sensor detecting a real-time power turbine speed, generating the real-time power turbine speed signal, and sending the real-time power turbine speed signal to the computer processor.

13. The method of claim 11, further comprising a sensor detecting a real-time power turbine torque, generating a real-time power turbine torque signal, and sending the real-time power turbine torque signal to the computer processor.

14. The method of claim 11, further comprising the computer processor generating a stability bleed signal based at least in part on the generated torque request and sending the stability bleed signal to the gas generator of the gas turbine engine to control the power turbine torque of the gas turbine engine.

15. The method of claim 11, further comprising the computer processor using inversion of a dynamic model of a rotor to generate the torque request, and the computer processor using inversion of a dynamic model of a gas generator to generate the fuel flow signal and the inlet guide vane signal.

16. A turboshaft engine, comprising:

a gas generator section;

a power turbine section downstream of the gas generator section; and

a control system in communication with the gas generator section and the power turbine section, the control system including at least one computer processor configured to;

receive a collective lever angle signal and a power turbine speed signal,

generate a torque request based at least in part on the collective lever angle signal and the power turbine speed signal,

generate a fuel flow signal and an inlet guide vane signal based at least in part on the generated torque request, and

send the fuel flow signal and the inlet guide vane signal to the gas generator section in order to control a torque of the power turbine section.

17. The turboshaft engine of claim 16, wherein the computer processor is configured according to a cascaded architecture.

18. The turboshaft engine of claim 17, wherein the cascaded architecture includes an outer loop control module to generate the torque request and an inner loop control module to generate the fuel flow signal and the inlet guide vane signal.

19. The turboshaft engine of claim 18, wherein the outer loop control module uses dynamic inversion of a rotor model to generate the torque request, and wherein the inner loop control module uses dynamic inversion of a gas generator model to generate the fuel flow signal and the inlet guide vane signal.

20. The turboshaft engine of claim 16, wherein the computer processor is further configured to generate a stability bleed signal based at least in part on the generated torque request, and send the stability bleed signal to the gas generator section in order to control the torque of the power turbine section.