Brushless Asynchronous Starter for Aircraft Gas Turbines
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Solution Overview
Problem
Conventional DC starters for aircraft gas turbines are sensitive to external parameters, leading to ignition faults and high maintenance costs, and alternative solutions using electric generators with power electronics are heavy and limited to shared configurations.
Innovation Solution
A method and system utilizing a brushless asynchronous electric machine powered by DC voltage, with a control system that converts DC voltage into a three-phase voltage system to control the machine, optimizing torque generation through a scalar control law dependent on target torque ratio and rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DC starter motor is used to start the gas turbine, then the starting function is achieved, but the system becomes sensitive to external parameters leading to ignition faults and high maintenance costs
Solution Approach 1:
The patent changes the fundamental parameters of the starting system by replacing the DC motor with a brushless asynchronous electric machine powered by a DC-AC converter. This transformation alters the operating characteristics from direct DC motor control to inverter-controlled AC motor operation, fundamentally changing how the system responds to external parameters like temperature and battery state, thereby reducing sensitivity while maintaining starting reliability
2Ease of operation
If a DC starter motor is used, then the starting function is provided, but maintenance costs increase due to brush wear and sophisticated electronics
Solution Approach 1:
The patent extracts and eliminates the problematic brush component from the electric machine design by adopting a brushless asynchronous motor. This removal of the brush component directly addresses the maintenance issue while preserving the starting function through the brushless commutation system controlled by the DC-AC converter
3Reliability
If an electric generator with power electronics is used as a starter, then the starting function is achieved, but the system mass increases to around 25 to 30 kg
Solution Approach 1:
The patent applies multi-functionality by enabling the electric generator to serve dual purposes: generating electrical power during normal operation and functioning as a starter motor when needed. The DC-AC converter enables bidirectional operation, allowing the same component to provide both generation and starting functions, thereby eliminating the need for separate dedicated starting motors and reducing overall system mass
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
This approach reduces maintenance requirements, optimizes starting torque in real-time, and provides a lighter, cheaper solution for starting aircraft gas turbines, minimizing ignition faults and operational costs.
Implementation Method 1
an electric machine of brushless asynchronous type and being powered with a DC voltage
Implementation Method 2
converting, by the control system, the DC voltage into a three-phase voltage system for controlling the electric machine
Data Source
AI summary
A gas turbine of an aircraft includes start-up system configured to drive a shaft of the gas turbine in rotation. The start-up system includes a control system and a brushless asynchronous electric machine and is supplied with a DC voltage. A method for starting the gas turbine includes the steps of converting the DC voltage into a three-phase voltage control system based on a first value representative of a rotational speed of a rotor of the electric machine and on a second value representative of a ratio of a determined target torque of the electric machine, suitable for driving the rotation of a shaft of the gas turbine at a determined speed, to the maximum theoretical torque that the electric machine is able to produce at the determined rotational speed of the rotor.