Synchronous Machine Fault Tolerance via Phase Shift Control
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Solution Overview
Problem
Embedded synchronous electrical machines in gas turbine engines face challenges with open-circuit faults, leading to torque ripple and reduced power output due to the non-cancellation of second harmonic power vectors, making them difficult to maintain and replace.
Innovation Solution
Incorporating phase shift means, such as power electronic converters, to detect and isolate faulty phases, adjust phase angles, and produce controlled phase shifts between voltage and current, ensuring the vector sum of second harmonic power vectors is zero, thereby eliminating torque ripple and maximizing power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the synchronous electrical machine is embedded in the gas turbine engine, then the mechanical transmission system is removed providing operational and efficiency benefits, but the synchronous electrical machine becomes difficult to remove and replace if there is a fault
Solution Approach 1:
The synchronous electrical machine is divided into modular components: a stator assembly that can be detached from the gas turbine engine, and a rotor assembly that remains with the engine. This segmentation allows the stator to be easily removed and replaced for maintenance while the rotor stays embedded, resolving the contradiction between embedded operation and ease of repair.
Solution Approach 2:
The stator assembly is extracted as a separate removable component from the gas turbine engine. This extraction allows the stator to be maintained independently without affecting the embedded rotor, enabling easy replacement of the stator while keeping the rotor permanently installed in the engine.
2Reliability
If a fault occurs in one phase of the synchronous electrical machine, then operation can continue with reduced power, but torque ripple increases due to non-cancellation of second harmonic power vectors
Solution Approach 1:
The control system dynamically changes the operating parameters of the remaining healthy phases when a fault is detected. By adjusting the current magnitude and phase angle in the healthy phases, the system compensates for the missing phase and restores the cancellation of second harmonic power vectors, eliminating torque ripple while maintaining fault-tolerant operation.
Solution Approach 2:
The control system continuously monitors the operational status of each phase and provides feedback control. When a phase fault is detected, the feedback mechanism triggers automatic adjustment of the healthy phases' parameters to maintain balanced operation and eliminate harmful torque ripple, ensuring reliable fault-tolerant operation.
3Weight of moving object
If permanent magnet designs are used in the synchronous electrical machine, then size and weight are reduced, but the machine becomes more sensitive to faults and requires fault tolerant design
Solution Approach 1:
The permanent magnet synchronous electrical machine is segmented into a removable stator and a permanent rotor. This segmentation allows the lightweight permanent magnet rotor to remain embedded in the gas turbine engine while the stator can be easily replaced if faults occur, maintaining the weight benefits of permanent magnets while improving fault tolerance through component replaceability.
Solution Approach 2:
The control system implements parameter changes in the healthy phases to compensate for faults in permanent magnet synchronous machines. By adjusting current parameters and phase angles, the system maintains optimal performance and eliminates torque ripple even when faults occur in the permanent magnet design, reducing sensitivity to faults.
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 allows for fault-tolerant operation with minimal torque ripple and maximized power output, even with an open-circuit fault, reducing vibration and potential damage, and enabling efficient maintenance by simplifying the mechanical transmission system.
Implementation Method 1
phase shift means arranged to produce a controlled phase shift between the voltage(emf) and the current within the remaining phases of the synchronous electrical machine to adjust the phase angle of the second harmonic powers
Implementation Method 2
detecting means arranged to detect a fault in at least one of the phases of the synchronous electrical machine
Data Source
AI summary
A synchronous electrical machine comprises a plurality of phases and detecting means arranged to detect an open-circuit fault in at least one of the phases of the synchronous electrical machine. Isolating means is arranged to isolate the at least one phase of the synchronous electrical machine with the fault. Phase shift means are arranged to produce a controlled phase shift between the voltage and the current within the remaining phases of the synchronous electrical machine so as to adjust the phase angle of the second harmonic powers produced by the remaining phases of the synchronous electrical machine such that the vector sum of the second harmonic power vectors of the remaining phases of the synchronous electrical machine is zero to eliminate torque ripple. The phase shift means is arranged to adjust the phase angle of all the remaining phases by the same predetermined angle to maximize the torque ripple-free power output of the synchronous electrical machine.