Permanent Magnet Rotor Design for Reduced Overheating
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Summary
Problems
Existing dynamoelectric machines with permanent magnets experience overheating due to high-frequency eddy currents, which are not effectively addressed by current production methods that increase ohmic resistance, and the use of segmented magnets is expensive.
Innovation solutions
A rotor design with permanent magnets featuring conical thickenings and indentations on their surface, which increases ohmic resistance and enhances heat dissipation, combined with a binding thread that can be easily integrated into the surface structure, and the use of powder injection molding for manufacturing.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If permanent magnets are pressed, sintered and finished using conventional methods, then a smooth surface is achieved, but the electric resistance to high-frequency currents is reduced leading to increased temperature and magnetic flux effects
Why choose this principle:
The patent applies surface curvature through corrugations (undulating patterns) on the permanent magnet surfaces. These corrugations create a non-smooth surface topology that increases the path length for eddy currents, thereby increasing ohmic resistance and reducing temperature buildup from high-frequency currents during motor operation.
Principle concept:
If permanent magnets are segmented to increase ohmic resistance, then high-frequency current effects are reduced, but production cost increases significantly
Why choose this principle:
Instead of physically segmenting the magnets into separate pieces, the patent uses continuous surface corrugations that achieve the same electrical resistance effect. This approach maintains manufacturing simplicity while achieving the desired reduction in eddy current effects and magnet temperature.
Application Domain
Data Source
AI summary:
A rotor design with permanent magnets featuring conical thickenings and indentations on their surface, which increases ohmic resistance and enhances heat dissipation, combined with a binding thread that can be easily integrated into the surface structure, and the use of powder injection molding for manufacturing.
Abstract
A rotor for a dynamoelectric rotary machine includes a rotor stack, a plurality of permanent magnets, and a binding designed to fix the permanent magnets to the rotor stack, said binding including a binding thread. The permanent magnets each have at a surface of the permanent magnet a shape deviation designed to receive the binding thread and to comprise a conical thickening and an indentation, with a height difference between a highest point of the thickening and a lowest point of the indentation being at least 2% of a thickness of the permanent magnet and at most 20% of the thickness of the permanent magnet.