Fault-Tolerant Electric Machine with Four-Phase Stator
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Solution Overview
Problem
Current fault-tolerant designs for electric machines in aerospace applications often result in overrating in terms of power, weight, and installation volume, and complexity, particularly in more electric engines and aircraft systems, where single fault-tolerance is required but at the expense of increased capacity and complexity.
Innovation Solution
A fault-tolerant radial flux rotary electric machine with a permanent magnet rotor and an alternate-wound stator featuring four independent electrical phases, optimized tooth geometry, and a cooling scheme, utilizing a transposed conductor to reduce eddy currents and enhance fault tolerance, allowing for reduced overrating and complexity while maintaining operational reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two individual starter-generator devices are installed per engine with each connected at a respective pad on the accessory gearbox, then single fault-tolerance is achieved, but installation volume and complexity increase substantially
Solution Approach 1:
Two starter-generator devices are packaged with a common housing and share a common shaft, reducing installation volume while maintaining single fault-tolerance through duplexing of electrical components
Solution Approach 2:
The common mechanical parts (housing, shaft) serve both starter-generator devices, allowing the system to perform multiple functions with shared infrastructure, reducing overall installation volume
2Reliability
If two individual starter-generator devices are installed per engine with each connected at a respective pad on the accessory gearbox, then single fault-tolerance is achieved, but device complexity increases
Solution Approach 1:
The common housing and shaft merge mechanical functions, reducing the number of separate mechanical assemblies and simplifying installation while maintaining electrical redundancy for fault-tolerance
3Device complexity
If two starter-generators are packaged with a common housing and common shaft, then installation complexity is reduced, but electrical generation capacity is overrated by 100 percent
Solution Approach 1:
The system dynamically reconfigures electrical connections based on operational mode (single-phase or two-phase operation), allowing optimal power utilization without permanent overrating while maintaining fault-tolerance capabilities
4Weight of moving object
If independent four-phase drive systems are used for aircraft fuel pump, then weight is reduced by limiting overrating to 33 percent, but drive system complexity increases
Solution Approach 1:
The drive system dynamically switches between single-phase and two-phase operation modes, reducing weight by limiting overrating to 33 percent while managing complexity through controlled electrical reconfiguration rather than permanent dual-system architecture
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 achieves a substantial weight saving and reduced complexity while maintaining single fault-tolerance, enabling efficient and reliable operation in aerospace applications by distributing power across four phases, thereby minimizing the impact of a single phase failure.
Implementation Method 1
the stator comprises coils formed of a transposed conductor to reduce eddy currents
Implementation Method 2
permanent magnet rotor having fourteen poles, and an alternate-wound stator having sixteen slots and four coil pairs
Implementation Method 3
the coils are formed so as to have a substantially parallelogram-shaped cross section, thereby providing a void with a substantially triangular cross section in each slot for flow of a cooling fluid
Data Source
AI summary
Fault-tolerant radial flux rotary electric machines are provided. One such machine comprises: a permanent magnet rotor having fourteen poles; and an alternate-wound stator having sixteen slots and four coil pairs, each coil pair forming part of one of four independent electrical phases.