Electric Braking Control for Low-Pressure Shaft Compressor Stability
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Solution Overview
Problem
Existing hybrid aircraft motor assemblies face instability risks in the low-pressure compressor of gas turbine engines, particularly during thrust reverser activation and air flow disturbances, which can lead to inefficiencies and energy loss.
Innovation Solution
A method and control unit that utilize a first electric machine to extract mechanical work from the low-pressure shaft in response to thrust reverser activation and air flow disturbances, stabilizing the compressor by braking the shaft and converting energy into electrical form for storage or use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bleed valves are opened at the outlet of the low-pressure compressor to avoid instability, then the risk of surge is reduced, but energy efficiency is lost
Solution Approach 1:
The patent replaces the mechanical bleed valve system with an electric machine coupled to the low-pressure shaft. The electric machine extracts mechanical work to brake the shaft rotation, providing compressor stability without requiring bleed valves to open and discharge compressed air, thereby maintaining energy efficiency while ensuring reliability
Solution Approach 2:
The electric machine acts as an intermediary between the low-pressure shaft and the electrical system. It converts mechanical energy from the shaft into electrical energy, providing a controlled braking effect that stabilizes the compressor without the energy loss associated with bleed valve operation
2Stability of the object's composition
If the low-pressure shaft inertia is high, then the shaft maintains rotational momentum, but the response time to stabilize the compressor during instability is slow
Solution Approach 1:
The control system monitors compressor operation and activates the electric machine to extract mechanical work when instability conditions are detected (such as thrust reverser activation or air flow disturbances). This feedback mechanism enables rapid response to stabilize the compressor, overcoming the delay that would otherwise result from the high inertia of the low-pressure shaft
Solution Approach 2:
The system proactively applies braking torque through the electric machine when instability conditions are anticipated or detected, counteracting the destabilizing effects before they can fully develop. This preliminary anti-action compensates for the slow response inherent in high-inertia systems by acting preemptively
3Reliability
If thrust reverser is activated or air flow is disturbed, then braking of the low-pressure shaft is needed to maintain stability, but conventional methods cause energy loss
Solution Approach 1:
The patent converts the potentially harmful braking action (which would normally dissipate energy as heat through friction) into a beneficial process by using the electric machine to convert the mechanical energy into electrical energy. The braking torque stabilizes the compressor during thrust reverser activation or air flow disturbances, while the extracted energy is recovered rather than lost
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the stability margin of the low-pressure compressor, retrieves energy efficiently, and maintains system efficiency without opening bleed valves, applicable to various gas turbine engine types including turboprop and turboshaft engines.
Implementation Method 1
a take-off of mechanical work is ordered from the first electric machine to brake a rotation of the low-pressure shaft
Data Source
AI summary
A method for controlling a motor assembly. This motor assembly includes at least a first electric machine and a gas turbine engine. The gas turbine engine includes a low-pressure shaft and a high-pressure shaft. The electric machine is coupled to the low-pressure shaft, and the control method includes a step in which a take-off of mechanical work is ordered from the first electric machine to brake a rotation of the low-pressure shaft in response to an activation of a thrust reverser of the gas turbine engine and/or a disturbance of the air flow in a transverse plane at an air intake of the gas turbine engine. A control unit suitable for carrying out this method, a motor assembly incorporating this control unit, the electric machine and the gas turbine engine, and a computer program to carry out this method.