Rotary Electric Machine Two-Layer Magnet Angle Design
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Solution Overview
Problem
In two-layered embedded magnet type rotary electric machines, the saturation of magnetic flux density can occur due to local denseness of magnetic fluxes, leading to a potential decrease in torque output.
Innovation Solution
The rotary electric machine design features a rotor with permanent magnets disposed in a two-layered structure, where the outer layer magnets have a larger angle with the magnetic pole center than the inner layer magnets, creating a wider magnetic path at the pole center and relieving saturation, while also equalizing stress on the center bridges to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the width of the magnetic path between permanent magnets of two layers is kept constant, then the structure is simplified, but local denseness of magnetic flux occurs causing saturation of magnetic flux density and torque decrease
Solution Approach 1:
The patent applies local quality by making the magnetic path width variable rather than constant. Specifically, the magnetic path width is increased at the pole center region where magnetic flux density saturation occurs, while maintaining other structural characteristics. This localized modification relieves the saturation of magnetic flux density without requiring a complete redesign of the entire magnetic path structure, thereby resolving the contradiction between structural simplicity and torque output.
2Strength
If the length of center bridge is increased to support larger permanent magnets, then the strength is improved, but the device size increases
Solution Approach 1:
The patent applies dimensionality change by modifying the center bridge structure in the circumferential direction rather than simply increasing its length in the radial direction. The center bridge is designed with an extended circumferential length that allows it to span across a wider magnetic pole width, providing enhanced support for larger permanent magnets. This approach strengthens the center bridge while minimizing the increase in overall rotor volume by utilizing the circumferential dimension more effectively.
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 enhances torque output by preventing magnetic flux saturation and reducing stress on the rotor core, allowing for downsizing and improved efficiency of the rotary electric machine.
Implementation Method 1
magnetic torque which is generated by cooperation of a rotating magnetic field of a stator with the permanent magnets
Implementation Method 2
cooperation of a rotating magnetic field of a stator with the permanent magnets
Implementation Method 3
reluctance torque which is generated based on a magnetic anisotropy of the rotor core
Implementation Method 4
stress acting on a center bridge between permanent magnets adjacent to each other due to a centrifugal force or an excitation force due to the rotation
Data Source
AI summary
A rotary electric machine includes a stator and a rotor. The rotor includes a rotor core and a plurality of permanent magnets. The permanent magnets are disposed to be divided into two layers, the two layers being a layer on the outer peripheral side and a layer on the inner peripheral side of the rotor core, and the permanent magnets are disposed line-symmetrically with respect to a magnetic pole center of the rotor core and in a V-shape or a U-shape in each of the two layers. An angle that each of the permanent magnets disposed on the outer peripheral side makes with the magnetic pole center of the V-shape or the U-shape is larger than an angle that each of the permanent magnets disposed on the inner peripheral side makes with the magnetic pole center of the V-shape or the U-shape.