Rotor Permanent Magnet Module Intermediate Wall Design
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Solution Overview
Problem
The challenge is to securely attach larger permanent magnet modules on the rotor of an electric machine to reduce the number of poles while managing increased centrifugal forces, which can disrupt the desired output frequency, especially at higher rotation speeds like those in wind turbines.
Innovation Solution
The solution involves dividing the compartment within the cover of the permanent magnet module into two sub-compartments with an intermediate wall that extends into a groove on the rotor, providing additional fastening means to securely attach the magnet module, allowing the permanent magnets to be positioned closer together to reduce stray flux and enhance attachment strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the size of permanent magnet modules is increased in the circumferential direction to reduce the number of poles, then the pole number is reduced and output frequency can be maintained at desired levels, but bigger centrifugal forces are generated on the cover during rotation
Solution Approach 1:
The compartment is divided into two sub-compartments by an intermediate wall, allowing the permanent magnet module to be segmented into smaller sections. This segmentation enables better distribution of centrifugal forces while maintaining the overall larger size needed for reduced pole numbers.
Solution Approach 2:
The intermediate wall extends in the radial direction (perpendicular to the circumferential direction), adding a dimensional element that provides additional fastening capability. This radial extension allows the wall to engage with the rotor body more effectively, distributing loads across multiple dimensions.
2Productivity
If bigger permanent magnet modules are used to reduce pole number, then fewer poles are required in the electric generator, but the fastening of the permanent magnet module must be improved to withstand bigger centrifugal forces
Solution Approach 1:
The compartment is divided into two sub-compartments by an intermediate wall, allowing the permanent magnet module to be segmented into smaller sections. This segmentation enables better distribution of centrifugal forces while maintaining the overall larger size needed for reduced pole numbers.
Solution Approach 2:
The intermediate wall acts as an intermediary structure between the permanent magnets and the rotor body. It provides additional fastening means that mediate the connection, distributing mechanical stresses and improving overall attachment reliability.
3Length of moving object
If the intermediate wall is made thinner to allow fastening means to pass through, then the opposed side edges of permanent magnets can be positioned closer together, but the structural strength of the intermediate wall must be sufficient
Solution Approach 1:
The thickness of the intermediate wall is optimized as a critical parameter. By carefully selecting the wall thickness, the design achieves a balance between allowing fastening means to pass through (requiring thinner walls) and maintaining sufficient structural strength to withstand operational loads.
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 arrangement allows for higher rotation speeds and easier adaptation of rotor diameter to different pole numbers, improving the attachment strength of the permanent magnet modules and reducing stray flux between partial poles.
Implementation Method 1
A bigger permanent magnet module produces, however, bigger centrifugal forces on the cover compared to a smaller permanent magnet module when the rotor rotates.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The rotor comprises an outer surface (22A) provided with a plurality of rows (A1, A2) of surface mounted permanent magnet modules (200) distributed along a perimeter of the outer surface of the rotor, each row comprising at least one surface mounted permanent magnet module. The permanent magnet module (200) comprises a cover (100) having a top part (110) forming a compartment (130). The top part of the cover comprises at least one intermediate wall (150) extending in the direction of the row or in an axial direction (X-X) along the whole height of the compartment and dividing the compartment into at least two separate sub-compartments (135, 136), whereby each sub-compartment houses at least one permanent magnet (35). The intermediate wall comprises fastening means (161, 162) for attaching the intermediate wall to the rotor.