Mixed Mode Power Generation Architecture for Aircraft Engines
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Solution Overview
Problem
Aircraft electric power generation systems face challenges in providing cost-effective and lightweight solutions for power generation due to the need for regulated voltage and frequency, which is costly and heavy, especially when using constant or variable-frequency generators, while wild-source generators are not suitable due to their inability to provide stable frequency for high-quality loads.
Innovation Solution
A mixed-mode electric power generation system that combines a wild-source generator for voltage and frequency tolerant loads and a regulated voltage generator for intolerant loads, utilizing mechanical power from both low-pressure and high-pressure spools of an aircraft engine, allowing for efficient power distribution based on load requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a regulated voltage constant-frequency generator is used, then power quality for voltage and frequency intolerant loads is improved, but weight and cost increase
Solution Approach 1:
The power generation system is divided into two separate generators: a regulated voltage constant-frequency generator for voltage and frequency intolerant loads, and a wild-source variable-voltage variable-frequency generator for tolerant loads. This segmentation allows each generator to be optimized for its specific function, reducing overall system weight while maintaining power quality where required.
Solution Approach 2:
Different parts of the power generation system provide different power qualities according to local needs. The regulated generator provides high-quality stable frequency power to sensitive loads, while the wild-source generator provides variable frequency power to tolerant loads, optimizing the overall system configuration.
2Weight of moving object
If a wild-source generator is used, then weight and cost are reduced, but power quality for voltage and frequency intolerant loads deteriorates
Solution Approach 1:
The system segments loads into voltage and frequency tolerant and intolerant categories, connecting intolerant loads to the regulated generator and tolerant loads to the wild-source generator. This ensures weight reduction where possible while maintaining power quality where required.
Solution Approach 2:
Different power quality levels are provided to different parts of the system based on load requirements. Voltage and frequency intolerant loads receive regulated power, while tolerant loads receive variable frequency power, optimizing the balance between weight and power quality.
3Reliability
If mechanical couplings are used to provide constant-frequency output, then power quality is improved, but device complexity and cost increase
Solution Approach 1:
The system separates constant-frequency generation from variable-frequency generation, using mechanical couplings only where necessary for frequency stability, while allowing other parts to operate more simply with direct drive configurations.
Solution Approach 2:
The complex mechanical coupling system is extracted and replaced by using two separate generators with different frequency characteristics, eliminating the need for complex speed regulation mechanisms in the wild-source generator.
4Adaptability or versatility
If variable-frequency generator range is expanded, then adaptability to different loads is improved, but weight and cost increase
Solution Approach 1:
The system divides the load spectrum into two groups with different frequency requirements, allowing the wild-source generator to operate over a wide variable frequency range for tolerant loads without needing to provide constant frequency, thus reducing weight compared to a universal constant-frequency generator.
Solution Approach 2:
Different frequency ranges and stability levels are provided to different parts of the system based on load requirements, allowing the wild-source generator to be optimized for wide frequency range without the weight penalty of making it suitable for all load types.
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 the weight and cost of power generation systems by using wild-source generators for lower power quality loads, while maintaining high-quality power supply for sensitive loads, thus optimizing power generation efficiency and cost-effectiveness.
Implementation Method 1
a wild-source generator with a variable-voltage variable-frequency AC output that is coupled to receive mechanical power from a low-pressure spool
Implementation Method 2
a regulated voltage generator with variable and/or constant frequency output that is coupled to receive mechanical power from a high-pressure spool
Data Source
AI summary
An electric power generation system (EPGS) employs both a wild-source generator and a variable and/or constant frequency generator. The wild-source generator is coupled to receive mechanical power from a low-pressure spool on an aircraft engine and to generate in response a wild-source output for consumption by voltage and frequency-tolerant loads. The variable and/or constant frequency generator is coupled to receive mechanical power from a high-pressure spool on the aircraft engine and to generate in response a variable and/or constant frequency output for consumption by voltage and frequency-intolerant loads.