Embedded-Magnet Rotor Slot Geometry for Compact High-Efficiency Motors
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Solution Overview
Problem
Existing permanent magnet motors face challenges in achieving improved efficiency, reduced complexity, and smaller rotor diameter while maintaining effective torque generation.
Innovation Solution
The design incorporates a cylindrical rotor body with axially extending magnet slots, where the circumference of each slot has a specific shape comprising a first portion, a second portion, and a narrowing. This configuration allows for efficient magnetic pole formation and optimal torque generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional magnet slot designs are used, then manufacturing is simpler, but torque generation and efficiency are reduced
Solution Approach 1:
The magnet slot cross-section is divided into three distinct segments: a first portion extending from the outer circumference to a narrowing, a second portion extending from the narrowing to the rotor axis, and a narrowing portion connecting them. This segmentation allows each portion to be optimized independently for its specific function, improving overall torque generation while maintaining manufacturability through standardized components.
Solution Approach 2:
Different portions of the magnet slot are given different geometric qualities tailored to their local functions. The first portion has dimensions optimized for magnet insertion and positioning, the narrowing provides precise localization, and the second portion is optimized for magnetic flux distribution. This local optimization enhances torque generation without requiring complete redesign of the entire slot structure.
2Volume of moving object
If rotor diameter is reduced for compact design, then motor size is smaller, but efficiency and torque generation are compromised
Solution Approach 1:
The invention transitions from conventional two-dimensional magnet slot cross-sections to a three-dimensional configuration with axial extension. The magnet slots extend axially through the rotor body, and the magnets are positioned at specific axial locations within these slots. This dimensional change allows efficient use of the reduced rotor volume while maintaining high efficiency through optimized magnetic flux paths in three dimensions.
Solution Approach 2:
The magnet slots are nested within the rotor body structure, with the magnets positioned within the first portion of each slot and separated by the narrowing. This nested configuration maximizes the use of available space within the compact rotor diameter, allowing efficient torque generation without increasing overall rotor size.
3Volume of moving object
If magnets are positioned closer to the rotor axis to reduce diameter, then rotor size is smaller, but magnetic pole formation and torque generation are affected
Solution Approach 1:
The magnet slots are pre-configured with their specific three-dimensional shapes including the narrowing portion before magnet insertion. This preliminary structuring ensures that when magnets are placed in the first portion of the slots, they are automatically positioned at optimal locations for magnetic pole formation. The narrowing acts as a pre-established barrier that ensures correct magnet positioning, maintaining reliable magnetic pole formation even in the compact rotor design.
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 design achieves efficiencies above 90%, such as 93%, while allowing for a smaller rotor diameter, making it suitable for applications requiring compact motor designs with high efficiency.
Implementation Method 1
a plurality of magnets extending along the length of each of the magnet slots, where the magnets are positioned within the first portion and separated from the second portion by the narrowing, wherein a pair of adjacent magnet slots are oriented so that lines connecting the first and second radial positions of the respective slots taper towards a radius of the rotor body, and the magnets in the pair of the magnet slots form a magnetic pole
Data Source
AI summary
A rotor for a permanent motor includes a cylindrical rotor body, a plurality of magnet slots, wherein a circumference of each of the magnet slots, in a plane perpendicular to the rotor axis, has a specific shape, wherein the specific shape comprises a first portion, a second portion and a narrowing between the first and second portions. The rotor comprises a plurality of magnets extending along the length of each of the magnet slots, where the magnets are positioned within the first portion and separated from the second portion by the narrowing, wherein a pair of adjacent magnet slots are configured so that they taper towards a radius of the rotor body, and so that the magnets in a pair of the magnet slots form a magnetic pole.