Irregular Polyhedron Magnet Assembly for Demagnetization Protection
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Solution Overview
Problem
Permanent magnet machines in electric vehicles experience demagnetization due to external magnetic fields and temperature changes, leading to reduced output torque and efficiency.
Innovation Solution
The use of an irregular polyhedron shaped magnet assembly with varying thickness along the magnetization axis, where the cross-sectional area is greater at the ends than at the central portion, reduces demagnetization by altering the magnet thickness to counteract the induced magnetic field from the stator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the magnet assembly uses a uniform thickness design, then the manufacturing process is simple, but the corners experience demagnetization under external magnetic fields and temperature changes
Solution Approach 1:
The magnet assembly employs non-uniform thickness distribution, with greater thickness at the corners compared to the center. This local variation in geometry provides enhanced demagnetization resistance specifically at the corner regions where external magnetic fields and temperature changes have the most impact, while maintaining a manufacturable overall structure.
2Reliability
If the magnet assembly increases thickness at corners to prevent demagnetization, then demagnetization resistance improves, but the magnet volume and cost increase
Solution Approach 1:
The design concentrates additional magnet material specifically at the corner regions where demagnetization risk is highest, rather than uniformly increasing thickness throughout the entire magnet assembly. This localized approach minimizes the total magnet volume required while achieving the necessary demagnetization protection at critical locations.
3Reliability
If the magnet assembly uses irregular polyhedron shape with varying thickness, then demagnetization is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The irregular polyhedron shape with varying thickness is designed to provide demagnetization protection through its geometric configuration rather than requiring extremely tight dimensional tolerances. The overall shape topology provides the protective effect, making the design more tolerant to manufacturing variations compared to designs relying on precise thin-film coatings or complex multi-component assemblies.
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 configuration effectively reduces or eliminates demagnetization at the corners of the magnets, improving the performance and efficiency of the electric machine while reducing magnet volume for cost savings.
Implementation Method 1
Coils in the stator are energized to create an electromagnetic flux that interacts with electromagnetic flux created by the permanent magnets of the rotor. The interaction of the fluxes causes the rotor to rotate.
Implementation Method 2
The permanent magnet machine includes a stator and a rotor. The rotor is constructed with permanent magnets.
Implementation Method 3
When subjected to external magnetic fields, including fields generated by the windings of the stator, and/or temperature changes, the magnetic properties of permanent magnets may change, leading to demagnetization
Data Source
AI summary
A permanent magnet machine includes a rotor and an irregular polyhedron shaped magnet assembly. The rotor may define at least one magnet opening and may be configured to rotate within a circular opening defined by a stator. The irregular polyhedron shaped magnet assembly may be disposed in the magnet opening and may define a magnetization direction, wherein a height along the magnetization direction and perpendicular with a lamination plane of the rotor is greater at both ends than at a central portion disposed therebetween.