Axial-Gap Stator Core Corner Curvature for Leakage Flux
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Solution Overview
Problem
Axial-gap rotating electric devices face inefficiencies due to leakage flux at the corners between teeth and back yokes in cores formed from molded powder compacts, leading to reduced torque and magnetic properties.
Innovation Solution
Incorporating a first curved section at the corners between teeth and back yokes with a curvature radius between 0.2 mm and 1.5 mm, and outer and inner curved sections with radii of 0.5 mm or larger, to reduce leakage flux and enhance magnetic properties, while also ensuring sufficient space for coils and alleviating mold stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the core is formed from molded powder compact with sharp corners between teeth and back yoke, then the manufacturing precision is improved, but leakage flux increases and magnetic properties deteriorate
Solution Approach 1:
The patent applies curvature by providing a curved section at the corner between the tooth and back yoke instead of a sharp corner. The curved section has a curvature radius R where 0.2 mm ≤ R ≤ 1.5 mm, which smooths the magnetic flux path and reduces leakage flux while maintaining manufacturing precision through controlled molding parameters.
2Loss of energy
If the curvature radius of the corner section is increased, then leakage flux is reduced and magnetic properties are improved, but the space for coil winding is reduced
Solution Approach 1:
The patent optimizes the curvature radius parameter within a specific range (0.2 mm ≤ R ≤ 1.5 mm) to achieve the best balance between reducing leakage flux and maintaining sufficient coil space. This parameter optimization ensures that the curved section is large enough to smooth magnetic flux paths but small enough to preserve winding space.
3Reliability
If the curved sections are added to alleviate mold stress, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent incorporates curved sections at critical corners of the core geometry to distribute and reduce stress concentration during molding operations. This curvature design improves mold durability and reliability while the curvature radius is controlled within specific limits to prevent excessive geometric complexity.
Data Source
AI summary
A core used in an axial-gap rotating electric device includes an annular back yoke and a plurality of teeth protruding in an axial direction that is perpendicular to a first flat surface of the back yoke. The plurality of teeth are provided on the first flat surface at intervals in a circumferential direction. The back yoke and the teeth are constituted of an integrally-molded powder compact. A first curved section that connects a peripheral surface of each tooth and the first flat surface of the back yoke is provided at a corner between the tooth and the back yoke. The first curved section has a curvature radius ranging between 0.2 mm and 1.5 mm inclusive.