Halbach Rotor Structure for Easier Magnet Fixing and Magnetization
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Solution Overview
Problem
Existing motor designs with Halbach arrays face challenges in fixing permanent magnets to a rotor core while maintaining their magnetized state, as adjacent magnets repel each other, and methods to magnetize magnetic members after fixing can result in unsuitable magnetic flux distribution.
Innovation Solution
A rotor design featuring a non-magnetic rotor core with recessed holes allows for the easy fixation and magnetization of magnetized portions arranged in a Halbach array, ensuring accurate positioning and efficient magnetic flux guidance during magnetization, enhancing magnetic field intensity and motor output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If permanent magnets are fixed to the rotor core in a magnetized state to form a Halbach array, then the magnetic field intensity and motor output are improved, but the permanent magnets are easily repelled by mutual magnetic forces making it difficult to fix them
Solution Approach 1:
The rotor magnet is divided into multiple independent permanent magnets arranged in a Halbach array pattern (N-S-N-S sequence). Each magnet is positioned in a separate groove, allowing individual fixation while maintaining the overall magnetic field configuration needed for high motor output.
Solution Approach 2:
A non-magnetic rotor core is introduced as an intermediary structure between the permanent magnets and the magnetic field. This non-magnetic core does not interfere with the magnetic flux while providing a stable mechanical foundation for fixing the magnets, preventing unwanted magnetic interactions with the core itself.
2Ease of manufacture
If magnetic members are fixed to the rotor core and then magnetized to form permanent magnets, then the permanent magnets can be easily fixed to the rotor core, but the magnetic flux emitted from the magnetizing yoke easily passes through the rotor core making it difficult to form the Halbach array
Solution Approach 1:
The rotor core has grooves with specific local geometries designed to concentrate and guide magnetic flux in particular directions. These grooves create localized magnetic field distributions that enable precise formation of the Halbach array pattern during magnetization, ensuring correct polarity arrangement.
Solution Approach 2:
The rotor core grooves are pre-formed with specific shapes and positions before the magnetization process. This preliminary structuring of the rotor core ensures that when magnetic members are later magnetized in place, the magnetic flux follows the predetermined paths needed to create the correct Halbach array configuration.
3Strength
If a magnetic rotor core is used to support the permanent magnets, then the structural strength is improved, but the magnetic flux distribution becomes unsuitable for forming the Halbach array
Solution Approach 1:
The rotor core combines non-magnetic material with locally optimized groove structures. The non-magnetic property prevents unwanted magnetic flux absorption by the core itself, while the groove geometry provides local flux concentration and guidance to achieve precise Halbach array formation.
Solution Approach 2:
The rotor assembly uses a composite structure combining non-magnetic rotor core material with magnetic permanent magnets. This composite approach allows the core to provide mechanical strength without interfering magnetically, while the magnets provide the required magnetic field distribution.
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
The solution enables effective fixation and magnetization of Halbach array configurations, increasing magnetic force between the rotor and stator, thereby improving motor output and simplifying the manufacturing process by reducing the complexity of magnet placement and alignment.
Implementation Method 1
a plurality of permanent magnets fixed to a rotor core form a Halbach array
Implementation Method 2
The rotor magnet has a plurality of magnetized portions arranged along a circumferential direction in a Halbach array
Implementation Method 3
when the magnetic members are magnetized, a magnetic flux emitted from a magnetizing yoke easily passes through the rotor core
Implementation Method 4
the magnetization directions of the adjacent permanent magnets are different from each other, the plurality of permanent magnets having the Halbach array as described above are easily repelled by mutual magnetic forces
Data Source
AI summary
One aspect of a rotor of the present invention includes: a rotor core rotatable about a central axis; and a rotor magnet fixed to an outer peripheral surface of the rotor core. The rotor magnet has a plurality of magnetized portions arranged along a circumferential direction in a Halbach array. The plurality of magnetized portions include a plurality of radially magnetized portions whose magnetization direction is a radial direction and a plurality of non-radially magnetized portions whose magnetization direction is different from the radial direction. The rotor core is a non-magnetic member that has a hole, recessed from a surface on one side in an axial direction of the rotor core to the other side in the axial direction and is made of a non-magnetic material. The hole is located on the radially inner side of the radially magnetized portion.