Embedded Electric Machines for High-Bandwidth Turbofan Thrust Control
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Solution Overview
Problem
Existing turbofan and turboprop jet engines rely primarily on fuel-based control systems, which are slow to respond to thrust response errors, leading to excess fuel usage, sluggish speed response, poor speed holding, increased engine wear, and other inefficiencies.
Innovation Solution
An engine control system that allocates thrust control between a fuel controller and an electric machine controller, utilizing high-frequency electric machine dynamics and low-frequency fuel dynamics to provide tighter control of thrust response, minimize thrust asymmetry, and reduce fuel system hardware design margins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fuel-based control systems are used for thrust control, then the system is simple to implement, but the response speed is slow leading to excess fuel usage and sluggish speed response
Solution Approach 1:
The patent merges fuel-based control and electric machine control into a unified hybrid control system. The controller integrates both fuel flow control and electric machine torque control to provide coordinated thrust management, achieving faster response while maintaining system manageability through unified control architecture.
Solution Approach 2:
The electric machine acts as an intermediary between the fuel system and the thrust output. By controlling the electric machine torque independently and rapidly, the system can compensate for fuel system response delays, effectively mediating the overall system response and achieving faster thrust adjustment without requiring immediate fuel system changes.
2Manufacturing precision
If fuel-based control systems are used, then the system structure is simple, but thrust response accuracy is poor resulting in excess fuel consumption
Solution Approach 1:
The control system segments the thrust control function into two independent channels: fuel-based control for baseline thrust management and electric machine control for precision thrust adjustment. This segmentation allows each subsystem to operate optimally within its capabilities while combining their advantages for overall precision, with the electric machine handling high-frequency corrections and the fuel system providing steady-state control.
Solution Approach 2:
The system changes the control parameter approach by introducing electric machine torque as an additional controllable parameter alongside fuel flow. This enables independent adjustment of thrust without changing fuel flow, allowing for precise thrust modulation and rapid response to thrust demands while maintaining fuel efficiency through optimized fuel-electric coordination.
3Ease of operation
If fuel-based control is used for thrust management, then the system is easier to operate, but speed holding capability is poor
Solution Approach 1:
The hybrid control system implements feedback control by continuously monitoring actual thrust and speed parameters, comparing them with target values, and adjusting both fuel flow and electric machine torque accordingly. This feedback mechanism automatically corrects speed deviations and maintains stable operation, with the controller adapting the feedback response based on operating conditions to maintain ease of operation while improving speed holding.
Data Source
AI summary
Systems and methods for high bandwidth control of thrust response for turbofan or turboprop engines are provided. Such systems and methods include an engine control system that processes a rate command and a feedback signal from an engine to generate separate fuel and electric machine control signals that respectively control fuel and electric machine dynamics of the engine to produce engine dynamics that result in desired thrust response.