Rotor Gaps Reduce Torque Ripple in Electric Motors
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Solution Overview
Problem
Electric motors with permanent magnets inserted in an iron core face increased torque ripple and radial exciting force due to the influence of the iron core, leading to vibration and noise, and existing solutions that reduce torque ripple also deteriorate motor efficiency.
Innovation Solution
A rotor design with a cylindrical or columnar iron core and equiangularly arranged magnets, featuring gaps at positions further from the axis than the magnets, with varying cross-sectional dimensions to reduce torque ripple while minimizing torque reduction, effectively concentrating magnetic flux and suppressing leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If slits are arranged at the portion of the iron core on the outer peripheral side of the inserted permanent magnets, then torque ripple is reduced, but magnetic force and torque are reduced, deteriorating motor efficiency
Solution Approach 1:
The invention applies different gap configurations to different regions of the iron core: the first end surface portion has gaps extending from the outer peripheral surface toward the inner peripheral surface, while the second end surface portion has gaps extending from the inner peripheral surface toward the outer peripheral surface. This local differentiation allows each region to contribute differently to reducing torque ripple while maintaining magnetic flux, thereby resolving the contradiction between reducing torque ripple and maintaining motor efficiency.
Solution Approach 2:
The invention uses asymmetric gap arrangements where the number, depth, or configuration of gaps in the first end surface portion differs from those in the second end surface portion. This asymmetry allows optimized control of magnetic flux distribution and torque ripple reduction without uniformly compromising magnetic force, thus maintaining motor efficiency while reducing torque ripple.
2Object-generated harmful factors
If gaps are formed in the iron core to reduce torque ripple, then vibration and noise are reduced, but torque is reduced
Solution Approach 1:
The invention divides the iron core into multiple segments along the axial direction, with each segment (first end surface portion, central portion, second end surface portion) having specifically configured gaps. This segmentation allows each region to independently contribute to vibration and noise reduction through localized gap structures, while the cumulative effect across all segments maintains sufficient torque production.
Solution Approach 2:
The invention varies gap parameters (such as gap depth, width, or number of gaps) across different axial positions and radial positions within each end surface portion. By optimizing these parameters locally, the invention achieves effective torque ripple reduction and vibration suppression while maintaining overall torque output through compensated regions.
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 rotor design reduces torque ripple, suppresses vibration and noise, and maintains motor efficiency by concentrating magnetic flux and minimizing torque reduction, achieving optimal performance in electric motors, compressors, and refrigeration air conditioners.
Implementation Method 1
an electric motor that improve the efficiency by using the rotor having the permanent magnets inserted in the iron core
Implementation Method 2
a plurality of magnets embedded in the iron core and equiangularly arranged with respect to an axis of the iron core, the plurality of magnets each penetrating through the first and second end surface portions and the central portion
Data Source
AI summary
A rotor includes an iron core that assumes a cylindrical or columnar shape, and a plurality of magnets embedded in the iron core and equiangularly arranged with respect to an axis of the iron core. The iron core includes a first end surface portion, a second end surface portion, and a central portion disposed between the first end surface portion and the second end surface portion. Each of the first end surface portion, the second end surface portion, and the central portion has one or more gaps formed at positions thereof remoter from the axis of the iron core than the magnets. A third cross-sectional planar dimension of the central portion is greater than a first cross-sectional planar dimension of the first end surface portion and a second cross-sectional planar dimension of the second end surface portion.