Permanent Magnet Generator Rotor Diameter-to-Length Ratio
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Solution Overview
Problem
Integrated drive generators in aircraft face challenges in maintaining a constant frequency of generated electric power due to varying input shaft speeds from gas turbine engines, which affects the performance of permanent magnet generators.
Innovation Solution
A rotor design for permanent magnet generators with a specific geometry, featuring a rotor body with cylindrical bore and flats for permanent magnets, surrounded by an outer ring, maintaining a diameter-to-length ratio between 3.2 and 3.4, is introduced to stabilize the output speed and frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the input shaft speed varies during gas turbine engine operation, then the generator can adapt to different engine conditions, but the generated electric power frequency becomes variable instead of constant
Solution Approach 1:
The rotor design incorporates dynamic geometric parameters (diameter-to-length ratio between 3.2 and 3.4) that optimize performance across varying speed conditions. The rotor body and outer ring configuration creates a dynamic system that maintains stable rotational characteristics despite input speed variations, enabling the generator to produce constant frequency power while adapting to different engine operating conditions.
Solution Approach 2:
The invention changes the geometric parameters of the rotor, specifically maintaining a diameter-to-length ratio between 3.2 and 3.4. This parameter optimization allows the rotor to maintain stable rotational speed and direction under varying input conditions, thereby ensuring constant frequency power generation while adapting to different engine speeds.
2Productivity
If a permanent magnet generator is added to provide power for accessory functions, then the integrated drive generator can support additional electrical loads, but the rotor design becomes more complex with challenges in maintaining stable speed and direction
Solution Approach 1:
The rotor is segmented into distinct functional components: a rotor body with cylindrical bore for structural support and magnet mounting, flats on the outer peripheral surface for magnet positioning, and an outer ring surrounding the permanent magnets. This segmentation allows each component to be optimized independently for its specific function while maintaining overall rotational stability and simplifying the manufacturing process.
Solution Approach 2:
The rotor employs a composite structure combining the rotor body (providing structural framework), permanent magnets (providing magnetic field), and outer ring (providing mechanical support and defining outer diameter). This composite design enables the rotor to generate electric power for accessory functions while maintaining stable speed and direction through the synergistic combination of different materials and components.
3Reliability
If the rotor has a specific diameter-to-length ratio between 3.2 and 3.4, then the output speed and frequency can be stabilized, but the manufacturing precision requirements increase
Solution Approach 1:
The invention specifies a diameter-to-length ratio range (3.2 to 3.4) rather than a single fixed value. This parameter range provides manufacturing flexibility while ensuring stable rotational performance. The range accommodates normal manufacturing variations without compromising the stability of output speed and frequency, thereby reducing stringent precision requirements compared to a fixed-dimensional design.
Solution Approach 2:
The rotor is divided into manufacturable segments (rotor body, outer ring, magnet assembly) that can be fabricated and assembled with standard tolerances. The cylindrical bore and flats are designed as discrete features that can be machined independently, allowing each component to be manufactured within conventional tolerance ranges while maintaining the overall diameter-to-length ratio within the specified 3.2 to 3.4 range.
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 rotor design ensures a consistent frequency of electric power generation by maintaining a stable speed and direction, effectively addressing the variability in input shaft speeds and enhancing the performance of permanent magnet generators in integrated drive systems.
Implementation Method 1
A rotor for a permanent magnet generator includes a rotor body extending between a first end and a second end, having a cylindrical bore and a plurality of flats on an outer peripheral surface. Permanent magnets are positioned at the flats.
Data Source
AI summary
A rotor for a permanent magnet generator includes a rotor body extending between a first end and a second end, having a cylindrical bore and a plurality of flats on an outer peripheral surface. Permanent magnets are positioned at the flats. An outer ring surrounds the permanent magnets and defines an outer diameter. A ratio of the outer diameter to an axial length between the first and second ends is between 3.2 and 3.4. An integrated drive generator and a method are also disclosed.