Multi-Mode Starter Control for Precise Gas Turbine Light-Off
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Solution Overview
Problem
Gas turbine engines face challenges in efficiently managing the transition from startup to light-off, particularly in controlling torque and speed to ensure reliable engine operation.
Innovation Solution
A starter assembly with a controller that modulates an electric motor in multiple control modes, including torque, acceleration, and speed control, to manage spool rotation during engine startup, ensuring precise speed and torque adjustments to achieve target thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the starter generates maximum torque during engine start-up, then the engine can be accelerated reliably, but the speed control precision deteriorates
Solution Approach 1:
The control system dynamically transitions between torque control mode and acceleration control mode based on real-time engine operating conditions. During initial start-up, torque control mode provides maximum torque for reliable acceleration. As the engine approaches light-off conditions, the system switches to acceleration control mode to maintain precise acceleration rates, thereby resolving the contradiction between reliable start-up and speed control precision.
Solution Approach 2:
The controller changes the control parameter from torque (during initial start-up) to acceleration rate (during acceleration phase). This parameter change allows the system to optimize performance at different stages: maximum torque ensures reliable start-up, while controlled acceleration rate maintains speed precision during the transition to light-off.
2Productivity
If the controller uses multiple control modes, then the engine operation efficiency improves, but the device complexity increases
Solution Approach 1:
The control process is segmented into distinct phases with dedicated control modes: torque control mode for initial start-up and acceleration control mode for the acceleration phase. Each mode is optimized for its specific phase, improving overall efficiency. The segmentation is managed through a structured state machine in the controller that transitions between modes based on predefined conditions, making the complexity manageable and systematic.
Solution Approach 2:
The single controller handles multiple control modes (torque control and acceleration control) within a unified architecture. This multi-functional approach allows one device to perform multiple functions, improving efficiency without proportionally increasing complexity. The controller uses a state machine to manage different operating modes, providing a universal solution that adapts to various engine conditions.
3Loss of time
If the spool acceleration is maintained at a preselected rate, then the time to reach target speed is reduced, but the torque control flexibility is reduced
Solution Approach 1:
The control system applies periodic transitions between torque control and acceleration control modes. During the acceleration phase, the acceleration control mode maintains a preselected acceleration rate, reducing time to reach target speed. The system periodically monitors engine conditions and transitions back to torque control mode when light-off conditions are approached, thereby maintaining both time efficiency and torque flexibility through rhythmic mode switching.
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
The solution enables efficient and reliable engine startup by maintaining spool acceleration and speed within specified limits, enhancing the likelihood of successful light-off and reducing operational variability.
Implementation Method 1
at least one electric motor coupled to a respective spool... The at least one electric motor is coupled to the respective at least one spool to drive the respective spool during an engine startup condition
Data Source
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AI summary
A starter assembly (60; 160) for a gas turbine engine (20; 120) may include, among other things, at least one electric motor (62; 162) coupled to a respective spool (30, 32; 132). A controller (66; 166) may be operable to modulate the at least one electric motor (62; 162) in a plurality of control modes (72; 172). The control modes (72; 172) may include a torque control mode (172-3), an acceleration control mode (172-1) and/or a speed control mode (172-2). A method for starting a gas turbine engine (20; 120) is also disclosed.