Annular Drive Magnet Segmentation for Cogging Torque Reduction
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Solution Overview
Problem
Existing motors with permanent magnets for reducing cogging torque face difficulties in mass production due to the complexity of skew magnetization, making them unsuitable for high-accuracy driving.
Innovation Solution
An annular drive magnet with magnetized areas divided into equiangular intervals and adjacent areas having different polarities, where the magnetization polarization line deviates from the boundary between divided areas, reducing cogging torque without the need for skew magnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If skew magnetization is used to reduce cogging torque, then cogging torque is reduced, but manufacturing difficulty increases
Solution Approach 1:
The annular drive magnet is divided into multiple magnetized areas with different polarities arranged at equiangular intervals. This segmentation allows each area to be magnetized independently in the radial direction, eliminating the need for complex skew magnetization while reducing cogging torque through the alternating polarity arrangement.
Solution Approach 2:
The magnetization polarization line is intentionally deviated from the boundary between divided areas in the circumferential direction. This asymmetric arrangement of magnetization relative to the geometric boundaries creates a magnetic field distribution that reduces cogging torque without requiring skew magnetization, thus simplifying manufacturing.
2Object-affected harmful factors
If skew magnetization is used to reduce cogging torque, then cogging torque is reduced, but mass production suitability decreases
Solution Approach 1:
The drive magnet is segmented into multiple independently magnetizable areas arranged circumferentially. Each area can be magnetized separately in the radial direction using standard magnetization equipment, enabling efficient mass production while the alternating polarity configuration reduces cogging torque.
Solution Approach 2:
The invention changes the magnetization configuration from skew magnetization (tilted relative to the rotation axis) to radial magnetization with deviated polarization lines. This parameter change in magnetization direction and arrangement maintains cogging torque reduction while making the process suitable for mass production through conventional magnetization techniques.
3Object-affected harmful factors
If magnetization polarization line deviates from divided area boundaries, then cogging torque is reduced, but magnetization complexity increases
Solution Approach 1:
The drive magnet is divided into discrete magnetized areas with clear boundaries. The magnetization polarization line is deviated from these boundaries in a systematic pattern, creating a configuration that reduces cogging torque while maintaining manufacturability through segmented, independent magnetization of each area.
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 allows for easier magnetization and significant reduction in cogging torque, making the motor suitable for mass production while maintaining high accuracy.
Implementation Method 1
the drive magnet includes a plurality of magnetized areas having an entire circumference divided into a multiple of 2 at equiangular intervals and includes a plurality of divided areas having an entire circumference divided into the same number as the number of magnetized areas at equiangular intervals, the two adjacent magnetized areas have different polarities
Data Source
AI summary
A motor with a permanent magnet is provided. A motor has a rotor and an annular drive magnet surrounding the rotor. The drive magnet includes a plurality of magnetized areas having an entire circumference divided into a multiple of at equiangular intervals and includes a plurality of divided areas having an entire circumference divided into the same number as the number of magnetized areas at equiangular intervals. The two adjacent magnetized areas have different polarities. In an inner circumferential surface of each divided area in the drive magnet, a distance D from a rotation center line of the rotor becomes longer from a center in a circumferential direction toward both ends of the area. A magnetization polarization line of the two adjacent magnetized areas deviates from a boundary between the two adjacent divided areas in the circumferential direction.