Feedforward Engine Controller Reduces Response Time
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Solution Overview
Problem
Existing gas turbine engine control systems face challenges in achieving desired response time while maintaining stability margin, particularly when using feedback controllers, which require iterative testing and are resource-consuming and expensive, especially when covering a large flight envelope.
Innovation Solution
A system comprising a feedforward controller that determines the required fuel flow for a gas turbine engine by receiving a requested engine speed and acceleration, using a steady-state fuel flow and the relationship between fuel flow and gas generator speed to output a command to a fuel flow metering valve, thereby reducing the need for iterative tuning and testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a feedback controller is used to control engine acceleration, then stability margin is maintained, but response time is slow
Solution Approach 1:
The feedforward controller calculates and applies the required fuel flow in advance based on the requested acceleration and engine speed, before the actual acceleration occurs. This preliminary action eliminates the delay inherent in feedback controllers that must wait for error signals, thereby improving response time while maintaining stability through the combined feedforward-feedback architecture.
2Manufacturing precision
If iterative testing is performed to tune the feedforward controller across the flight envelope, then control accuracy is improved, but resource consumption and cost increase
Solution Approach 1:
The feedforward controller uses real-time measurements of engine speed and requested acceleration to dynamically calculate the required fuel flow without requiring external tuning or testing. The controller serves itself by using operational data to determine control actions, eliminating the need for resource-consuming iterative testing across the flight envelope while maintaining control accuracy.
Data Source
AI summary
Systems and methods for controlling a gas turbine engine are provided. The system comprises an interface to a fuel flow metering valve for controlling a fuel flow to the engine in response to a fuel flow command and a controller connected to the interface and configured for outputting the fuel flow command to the fuel flow metering valve in accordance with a required fuel flow. The controller comprises a feedforward controller configured for receiving a requested engine speed and acceleration, obtaining a steady-state fuel flow for the requested engine speed and a relationship between fuel flow and gas generator speed, and determining the required fuel flow to obtain the requested engine acceleration as a function of the requested engine speed, the steady-state fuel flow, and the relationship between fuel flow and gas generator speed.