Sensorless Brushless Motor Rotor Positioning for Gas Turbine Starting
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Solution Overview
Problem
Starting a gas turbine engine with a sensorless brushless starter-generator is challenging, especially in applications like turbofans or turboprops, due to the need for a trial and error approach when the rotor may already be rotating from ground airflow, making it difficult to determine the correct rotor position for successful starting.
Innovation Solution
The method involves providing DC current to the windings to stop and position the rotor at a desired position relative to the stator, followed by energizing the stator windings to start the engine, using a rotor stopping and repositioning apparatus to eliminate the need for trial and error by ensuring the rotor magnets align correctly with the stator poles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a trial and error approach is used to start the engine without knowing rotor position, then the starting process can be initiated, but the starting reliability deteriorates due to incorrect rotor position assumptions
Solution Approach 1:
The patent applies preliminary action by using DC current to pre-position the rotor at a known position before starting the motor. This eliminates the trial-and-error approach by ensuring the rotor is in a predetermined position when AC current is applied to the stator windings, thereby guaranteeing reliable starting without requiring rotor position sensors.
2Adaptability or versatility
If the rotor is allowed to rotate freely due to ground airflow, then the engine can respond to environmental conditions, but the starting control deteriorates because rotor position becomes unknown
Solution Approach 1:
The system applies preliminary action by first applying DC current to position the rotor in a known position before transitioning to AC current for motor starting. This two-stage approach allows the system to handle residual rotor rotation from ground airflow while maintaining precise control during the starting process, as the rotor is deliberately positioned before the starting sequence begins.
3Manufacturing precision
If DC current is applied to position the rotor, then the rotor position precision improves, but the starting time increases due to the additional positioning step
Solution Approach 1:
The patent applies preliminary action by using DC current to pre-position the rotor before AC starting. While this adds a preliminary step, the positioning is achieved quickly through direct electromagnetic force from the DC current in the stator windings, and the overall starting time is reduced compared to trial-and-error methods that may require multiple failed attempts.
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 allows for reliable and efficient starting of gas turbine engines by ensuring the rotor is correctly positioned and aligned before energizing the stator windings, eliminating the need for trial and error and improving starting success rates even in applications with residual rotor rotation.
Implementation Method 1
providing DC current to at least one of the windings to position the rotor at a desired position with respect to the stator
Implementation Method 2
energizing the windings of the stator to start the gas turbine engine
Data Source
AI summary
A method and apparatus for starting a gas turbine engine using a brushless sensorless machine, the machine having a rotor and a stator with windings, the method including positioning the rotor at a desired position with respect to the stator and then energizing the windings of the stator.