Stator Core Tooth Welding Pattern for Eddy Current Reduction
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Solution Overview
Problem
The existing rotating electrical machines with staggered welds on the stator core face challenges due to overlapping welded portions, which increase eddy current loss and reduce operation efficiency, as the magnetic flux interlinks with these portions, leading to inefficiencies and potential cogging torque pulsation.
Innovation Solution
A rotating electrical machine design featuring a stator core composed of tacked electromagnetic steel sheets with first and second welded portions arranged in a staggered fashion on the tooth's lateral faces, reducing the overlap and distance between welded areas, thus minimizing eddy current loss and maintaining mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If welded portions are arranged in a staggered fashion on the inner peripheral face of the stator core, then eddy current loss is reduced, but the distance between the rotor and welded portions becomes short, causing magnetic flux interlinkage with overlapping portions
Solution Approach 1:
The tooth is divided into two lateral faces, with welded portions arranged on each face in a staggered fashion. This segmentation prevents overlapping of welded portions while maintaining the eddy current loss reduction benefit, as the magnetic flux path is interrupted at different positions on each lateral face.
Solution Approach 2:
The arrangement of welded portions is extended from a single-plane configuration to a three-dimensional configuration utilizing both lateral faces of the tooth. By distributing welded portions across two dimensions (front and back lateral faces) rather than one dimension (single lateral face), the invention eliminates overlapping while maintaining staggered arrangement benefits.
2Ease of manufacture
If electromagnetic steel sheets are welded together in the stacking direction, then manufacturing cost is reduced, but the plural electromagnetic steel sheets become electrically continuous, increasing eddy current loss
Solution Approach 1:
The welding arrangement is segmented across two lateral faces of the tooth rather than concentrated on one face. This segmentation maintains the electrical continuity benefit for structural integrity while distributing the welded portions to prevent overlapping, thereby reducing eddy current loss pathways.
Solution Approach 2:
The welded portions are strategically positioned on specific lateral faces of the tooth with staggered arrangements, creating local variations in the welding pattern. This local quality approach ensures that welded portions do not overlap in the magnetic flux path while maintaining necessary structural bonding between electromagnetic steel sheets.
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 configuration enhances the operation efficiency of the rotating electrical machine by reducing eddy current loss, suppressing cogging torque pulsation, and maintaining the magnetic characteristics and mechanical integrity of the stator core.
Implementation Method 1
the eddy current flows as the magnetic flux changes with time, which increases the eddy current loss
Data Source
AI summary
A rotating electrical machine includes a stator core including a plurality of stacked electromagnetic steel sheets, the stator core includes a core back and a tooth protruding from the core back, the tooth includes: plural first welded portions arranged on a first lateral face of the tooth with respect to a plane extending in a stacking direction of the electromagnetic steel sheets and equally dividing the width of the tooth, the first welded portions being arranged in the stacking direction; and plural second welded portions arranged on a second lateral face of the tooth with respect to the plane extending in the stacking direction, the second welded portions being arranged in the stacking direction, and the first welded portions and the second welded portions are staggered in the stacking direction.