Oriented-Flux Magnetic Ring Segmentation for Lower Eddy Current Loss
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Solution Overview
Problem
Existing rotating electric machines with Halbach topology permanent magnets suffer from high eddy current losses and material expansion-related stresses, and the segmentation of magnets increases manufacturing complexity and duration.
Innovation Solution
A method for dimensioning a multi-pole oriented-flux magnetic ring that involves determining characteristic dimensions and reference values to decide on circumferential segmentation of magnets into sub-magnets, minimizing eddy current losses and reducing the number of sub-magnets needed, thereby simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the magnet is segmented axially into ten magnets to minimize eddy current losses, then eddy current losses are reduced, but the manufacturing complexity and duration increase due to the need to manufacture, crop and glue many magnets
Solution Approach 1:
The patent applies segmentation by dividing the magnet into a smaller number of axially stacked segments (2-5 segments) rather than the conventional 10 segments. This segmentation reduces eddy current losses while minimizing manufacturing complexity by reducing the number of magnets that need to be manufactured, cropped, and glued to the rotor
Solution Approach 2:
The patent changes the segmentation parameter from the conventional 10 axial segments to an optimized range of 2-5 axial segments. This parameter change maintains sufficient eddy current loss reduction while significantly reducing manufacturing complexity and assembly duration
2Loss of energy
If the magnet is segmented axially into ten magnets to minimize eddy current losses, then eddy current losses are reduced, but the manufacturing duration increases due to the need to manufacture and assemble many magnets
Solution Approach 1:
The patent uses axial segmentation into 2-5 segments instead of 10 segments, which reduces the number of manufacturing and assembly operations required, thereby reducing manufacturing duration while still achieving sufficient eddy current loss reduction
Solution Approach 2:
The patent applies partial segmentation (2-5 segments instead of 10) which provides sufficient eddy current loss reduction without the excessive manufacturing effort and time required for full 10-segment segmentation
3Temperature
If the annular magnet is heated, then thermal expansion occurs, but stresses appear in the rotor liable to crack or break the annular magnet due to different coefficients of expansion between support and magnet
Solution Approach 1:
The patent segments the magnet axially into multiple pieces that are stacked to form the annular magnet. This segmentation creates expansion joints between segments that accommodate thermal expansion differences between the magnet and support, preventing stress buildup that would crack or break a solid annular magnet
Solution Approach 2:
The patent introduces axial dimensioning through segmentation, creating separation in the axial direction between magnet segments and the support structure. This dimensional approach allows thermal expansion in the radial direction without generating destructive stresses, as the segmented structure can accommodate expansion movements
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 eddy current losses and manufacturing complexity by optimizing the segmentation of magnets, ensuring fewer sub-magnets are required, which in turn decreases the duration and complexity of rotor assembly while maintaining magnetic performance.
Implementation Method 1
the magnetic fields of the successive magnets are oriented so as to amplify the resulting magnetic field in the air gap while eliminating the resulting magnetic field on the opposite side of the magnets
Implementation Method 2
when the annular magnet is heated stresses appear in the rotor, liable to crack or break the annular magnet
Implementation Method 3
the magnet generates high losses by eddy current
Data Source
AI summary
The method for dimensioning a multi-pole oriented-flux magnetic ring for a rotor of a rotating electric machine, where the magnetic ring includes a predetermined number of pairs of poles, and the magnetic ring is formed by at least one oriented-flux magnet. The method includes determining a characteristic dimension of the magnet equal to the minimum value out of the outer perimeter of the ring and the axial length of the ring, determining a reference value equal to the minimum value out of a predetermined reference length and twice the value Pi, comparing the characteristic dimension of the magnet with the reference value, and if the characteristic dimension of the magnet is greater than the reference value, the method comprises circumferentially dividing the magnet into at least two sub-magnets.