Multi-Pole Ring Magnet Layout for Low-Cogging Axial Flux Machines
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Solution Overview
Problem
The existing manufacturing processes for permanent magnet arrangements in axial flux machines are inefficient, requiring multiple individual magnets to be attached to a carrier plate, leading to increased manufacturing effort and potential for cogging forces that cause noise and vibration during operation.
Innovation Solution
Configuring multiple permanent magnets in one piece using powder metallurgy with controlled magnetic fields to form a multi-pole pair ring magnet, eliminating the need for a carrier plate and reducing cogging forces through obliquely angled magnet edges with varying helix angles, and using a rare earth material with a protective nickel-copper-nickel coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple individual permanent magnets are attached to a carrier plate, then the permanent magnet arrangement can be manufactured, but the manufacturing effort increases and installation space is required
Solution Approach 1:
Multiple individual permanent magnets are merged into a single piece permanent magnet arrangement manufactured using powder metallurgy processes. The magnetic powder is pressed and sintered to form an integrated structure containing multiple magnetized regions with different polarizations, eliminating the need for separate magnets and their individual attachment to a carrier plate.
Solution Approach 2:
The single piece permanent magnet arrangement performs multiple functions simultaneously: it provides the magnetic flux density required for motor operation, integrates the structural support function previously performed by the carrier plate, and maintains the multi-pole configuration needed for the axial flux machine's operation.
2Ease of operation
If a carrier plate is used to hold permanent magnets, then the permanent magnets can be assembled, but installation space is increased
Solution Approach 1:
The carrier plate and permanent magnets are merged into a single integrated component. The permanent magnet arrangement is manufactured as one piece that inherently maintains its structure without requiring a separate carrier plate for assembly and mounting.
Solution Approach 2:
The carrier plate is extracted or removed from the system entirely. The permanent magnet arrangement is designed and manufactured to be self-supporting and self-contained, eliminating the need for the additional carrier plate component that previously occupied installation space.
3Ease of manufacture
If straight edges are used on permanent magnets, then manufacturing is simpler, but cogging forces increase causing noise and vibration
Solution Approach 1:
Different regions of the permanent magnet arrangement have different edge geometries. The outer peripheral edges are designed with curved or oblique contours to reduce cogging forces, while the inner edges adjacent to the central axis maintain straight configurations for manufacturing simplicity. This local differentiation optimizes both performance and manufacturability.
Solution Approach 2:
The permanent magnet arrangement employs asymmetric edge designs where the outer edges have curved or oblique profiles rather than straight lines. This asymmetric geometry disrupts the uniform magnetic flux distribution that causes cogging forces, thereby reducing noise and vibration during motor operation.
4Productivity
If powder metallurgy with magnetic fields is used, then manufacturing effort is reduced, but the process complexity increases
Solution Approach 1:
The magnetic polarization is established during the manufacturing process itself through the application of magnetic fields in the powder metallurgy process. The magnetic powder is pressed and sintered while exposed to magnetic fields that define the polarization directions of different regions, so the magnetization is built into the structure during fabrication rather than requiring separate post-processing steps.
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 manufacturing complexity, minimizes installation space, decreases cogging forces, and enhances the magnetic flux density, resulting in a more efficient and quieter operation of axial flux machines.
Implementation Method 1
A plurality of permanent magnets arranged adjacent to one another can thereby be configured in one piece by using a powder metallurgy process for manufacture, with a weak magnetic field being applied at the same time as the powdered starting material is pressed, thereby specifying a preferred polarisation
Implementation Method 2
The blanks manufactured in this way are then magnetised in a magnetisation device by strong magnetic fields of different or opposite polarisation in regions of the blank arranged adjacent to one another
Implementation Method 3
One form of the permanent magnets is thereby determined by the magnetic flux density which is generated within the ring magnet by the permanent magnet and which drops to zero at the sides of the respective permanent magnet
Data Source
AI summary
A permanent magnet arrangement for use as a rotor or stator of an axial flux machine, in particular an axial flux machine of a door drive includes. permanent magnets arranged in a ring-shaped manner around a central axis and each magnetised in an axial direction running parallel to the central axis. Permanent magnets arranged adjacent to each other each have an opposite polarisation. All permanent magnets are configured in one piece and form a multi-pole pair ring magnet.