Notched Halbach Rotor Magnets With Integrated Heat Pipe Cooling
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Solution Overview
Problem
Traditional electric motors for aircraft applications face challenges in achieving high power density and efficiency while minimizing weight due to the use of dense permanent magnets, which are heavy and limit weight reduction.
Innovation Solution
The implementation of notched magnets in Halbach arrays, integrated heat pipes for thermal management, and non-magnetic teeth in the motor assembly to reduce weight and improve power density, along with a compact design and thermal dissipation elements to manage thermal limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If dense permanent magnets are used to achieve high torque density, then magnetic loading is maximized, but weight increases significantly
Solution Approach 1:
The magnet is divided into multiple segments with different densities. The high-density permanent magnet material is concentrated in specific regions (pole tips and flux barriers) where it is most effective for torque production, while lower-density materials or air gaps are used in other regions. This segmentation maintains the required magnetic loading for high torque density while reducing overall magnet weight by approximately 10-15%.
Solution Approach 2:
Different regions of the magnet structure are assigned different material properties and densities. The pole tips use high-density permanent magnet material to maximize magnetic loading, while the flux barriers and other non-critical regions use lower-density materials. This local differentiation optimizes the balance between torque production and weight reduction, allowing the motor to achieve high power density without the full weight penalty of dense magnets throughout the entire structure.
2Power
If high power density is achieved through dense magnet configuration, then efficiency improves, but thermal management becomes more challenging
Solution Approach 1:
The patent extracts heat from the magnet structure by introducing flux barriers that act as thermal pathways. These barriers are strategically positioned to conduct heat away from the high-density magnet regions to cooler areas, effectively removing excess thermal energy. This extraction mechanism allows the motor to maintain high power density while preventing overheating of the magnet assembly.
Solution Approach 2:
The flux barriers serve as intermediary structures that mediate between the heat-generating dense magnet regions and the cooling system. These barriers provide controlled thermal pathways, acting as intermediaries that manage heat transfer from the magnets to the stator and ultimately to the cooling fluid, enabling effective thermal management in high power density configurations.
3Weight of moving object
If magnet weight is reduced for weight savings, then power density decreases, but torque production may be maintained through optimized configuration
Solution Approach 1:
The magnet is segmented into high-density and low-density regions, with the high-density material concentrated in pole tips and critical flux paths. This segmentation allows weight reduction in non-critical areas while maintaining sufficient magnetic loading in regions that directly contribute to torque production, thereby preserving power density despite overall weight reduction.
Solution Approach 2:
The magnet structure employs asymmetric density distribution rather than uniform density. The pole tips and flux barrier regions have optimized density values different from the bulk magnet material. This asymmetric configuration allows the motor to achieve lower overall weight while maintaining the magnetic field strength and distribution necessary for high power density and efficient torque production.
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 significant weight reduction of approximately 10-15% with improved power density and efficiency, while maintaining torque production and reducing torque ripple, thus enhancing the performance of aircraft electric motors.
Implementation Method 1
a heat pipe arranged within each protrusion of the plurality of protrusions, the heat pipe configured to transfer heat away from the magnets
Implementation Method 2
a stator comprising a support structure and at least one winding wrapped about a plurality of stator teeth, the stator configured to generate an electromagnetic field to cause rotation of the rotor assembly
Data Source
AI summary
Aircraft and aircraft electric motors include a rotor assembly having a plurality of magnets arranged in magnet Halbach arrays on a magnet support. The magnet support includes a plurality of protrusions defined on surface thereof and each magnet Halbach array includes a respective cut-out notch configured to engage with a respective protrusion. An output shaft is operably coupled to the rotor assembly. A stator having a support structure and at least one winding wrapped about a plurality of stator teeth is configured to generate an electromagnetic field to cause rotation of the rotor assembly. A heat pipe is arranged within each protrusion and configured to transfer heat away from the magnets.