Wound Core Corner Geometry for Lower Iron Loss
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Solution Overview
Problem
Wound cores manufactured with bent steel sheets at corner portions suffer from increased core loss due to residual strain, which is not effectively mitigated without annealing.
Innovation Solution
Optimize the angle θ between 23° and 50° for the corner portions of wound cores by controlling the length of grain-oriented electrical steel sheets, ensuring the corner portions protrude outward to confine magnetic flux and reduce strain-induced iron loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If steel sheets are bent at corner portions to form a wound core without conventional large-scale forming, then manufacturing complexity and capital investment are reduced, but residual strain concentrates at bent portions causing increased core loss
Solution Approach 1:
The patent changes the geometric parameters of the bent portions, specifically controlling the radius of curvature and the angle θ (where tanθ = (L1-L2)/(2W)) to optimize the distribution of working strain. By adjusting these parameters, the corner portions protrude outward to confine magnetic flux while dispersing strain concentration, thereby reducing core loss without requiring conventional large-scale forming processes
Solution Approach 2:
The patent applies local quality by creating specific structural features at the corner portions only, where bent portions with controlled radius of curvature and specific angle θ protrude outward. This localized structural modification confines magnetic flux at critical areas and disperses working strain concentration precisely where needed, without affecting the overall manufacturing process simplicity
2Manufacturing precision
If steel sheets are bent with small radius of curvature (3 mm or less) to maintain core shape precision, then manufacturing precision is improved, but working strain concentrates at bent portions increasing iron loss
Solution Approach 1:
The patent simultaneously optimizes multiple parameters: the radius of curvature is kept small (3 mm or less) to maintain core shape precision, while the angle θ (where tanθ = (L1-L2)/(2W)) is specifically controlled to ensure corner portions protrude outward. This parameter combination achieves both precise core shaping and strain dispersion, reducing iron loss without sacrificing manufacturing precision
3Loss of energy
If corner portions are designed to protrude outward to confine magnetic flux, then iron loss is reduced, but the angle θ must be precisely controlled within 23° to 50° adding manufacturing constraint
Solution Approach 1:
The patent establishes a specific range for angle θ (23° to 50°, where tanθ = (L1-L2)/(2W)) that simultaneously achieves magnetic flux confinement and strain dispersion. This parameter range is designed to be practically manufacturable while delivering the dual benefits of reduced iron loss and simplified manufacturing process
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 solution results in a wound core with reduced iron loss even without annealing, improving manufacturing efficiency and reducing noise and elastic stress.
Implementation Method 1
the corner portions protrude outward to confine magnetic flux and reduce strain-induced iron loss
Implementation Method 2
the working strain is concentrated only on the bent portion (corner portion), so that strain removal by the annealing step can be omitted
Data Source
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AI summary
The wound core of the present invention has at least one arbitrary bent region 5A, in a plurality of corner portions (3), in which the corner portion (3) bulges outward to confine the magnetic flux flowing in the wound core so that the angle θ formed by the straight line PQ and the straight line PR satisfies 23° ≤ θ ≤ 50°.