Gas Turbine Engine Feedforward Controller for Acceleration Response
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Solution Overview
Problem
Existing gas turbine engine control methods using feedback controllers face challenges in achieving desired response time while maintaining stability, requiring iterative testing that is resource-consuming and expensive, especially when covering a large flight envelope.
Innovation Solution
A system and method utilizing a feedforward controller in conjunction with a feedback controller, which determines the required fuel flow to achieve engine acceleration based on requested engine speed, shaft inertia, and the relationship between fuel flow and acceleration power, allowing for non-iterative tuning and efficient control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a feedback controller is used for controlling gas turbine 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 parameters (shaft inertia, steady state fuel flow, and fuel flow to acceleration power relationship). This preliminary action allows the engine to respond immediately to acceleration requests without waiting for feedback errors to develop, thereby improving response time while the feedback controller maintains stability margin.
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 pre-stored engine parameters (shaft inertia, steady state fuel flow characteristics, and fuel flow to acceleration power relationship) to self-determine the required fuel flow for any given acceleration request. This self-service capability eliminates the need for extensive iterative testing and tuning across the flight envelope, as the controller can accurately compute fuel flow requirements using the established relationship between fuel flow and acceleration power.
Data Source
AI summary
Systems and methods for controlling an gas turbine engine are provided. The method comprises receiving a requested engine speed and obtaining a shaft inertia of the engine, a steady state fuel flow for the requested engine speed, and a relationship between fuel flow and acceleration power generated by the fuel flow. A required fuel flow to obtain an engine acceleration is determined as a function of the requested engine speed, the shaft inertia of the engine, the steady state fuel flow for the requested engine speed, and the relationship between fuel flow and acceleration power generated by the fuel flow. A command to a fuel flow metering valve is output in accordance with the required fuel flow.