Stator Core Coupling Pitch for Eddy Current Suppression
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Solution Overview
Problem
Conventional stators in rotary electric machines face challenges in reducing eddy current loss and securing geometrical tolerance due to the arrangement of electromagnetic steel plates, which affects the magnetic distribution and alignment of fixing and coupling portions.
Innovation Solution
The stator core is formed by stacking annular electromagnetic steel plates coupled with equal pitches in the circumferential direction, with coupling portions arranged at integral multiples of the central angle defined by magnetic poles, and fixing portions with through-holes aligned axially, allowing consistent magnetic distribution and preventing eddy currents, while ensuring geometrical tolerance through rotational build-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If annular electromagnetic steel plates are stacked with uniform stacking thickness to secure geometrical tolerance, then geometrical tolerance is improved, but eddy current loss cannot be reduced due to misalignment of coupling portions
Solution Approach 1:
The stator core is segmented into multiple annular electromagnetic steel plates stacked in the axial direction. Each plate is divided into effective portions (teeth and yoke) and non-effective portions (fixing-portion margins). This segmentation allows selective alignment of coupling portions while maintaining uniform stacking thickness for geometrical tolerance.
Solution Approach 2:
The coupling portions are preliminarily arranged at specific circumferential positions corresponding to integral multiples of the central angle before stacking. This preliminary positioning ensures that when plates are stacked with uniform thickness, the coupling portions automatically align axially to suppress eddy currents, without requiring post-stack adjustment.
Solution Approach 3:
The coupling portions act as intermediary elements between adjacent electromagnetic steel plates. By positioning these coupling portions at specific circumferential intervals (integral multiples of central angle), they mediate the magnetic flux distribution and prevent eddy current paths formed by misaligned stacking, while allowing the plates themselves to be stacked uniformly for geometrical tolerance.
2Manufacturing precision
If electromagnetic steel plates are rotationally built up to configure the stator core, then geometrical tolerance is secured, but it becomes impossible to reduce eddy current loss without considering fixing portion positions
Solution Approach 1:
Different portions of the electromagnetic steel plates have different functional qualities. The effective portions (teeth and yoke) are designed for magnetic flux conduction, while the fixing-portion margins are designed for mechanical fastening. The coupling portions within effective portions are specifically positioned to address eddy current suppression, creating local quality differentiation that resolves the contradiction between rotational build-up and eddy current loss reduction.
Solution Approach 2:
The coupling portions serve multiple functions simultaneously: they provide mechanical coupling between stacked plates, establish consistent magnetic distribution patterns, and suppress eddy currents by aligning with the central angle geometry. This multi-functionality allows a single structural feature to address both geometrical tolerance and eddy current loss without increasing overall device complexity.
3Loss of energy
If coupling portions are arranged to suppress eddy currents, then eddy current loss is reduced, but fixing portions may not align properly for mechanical fastening
Solution Approach 1:
The problem is solved by transitioning from two-dimensional circumferential arrangement to three-dimensional coordination. Coupling portions are arranged in the circumferential direction at integral multiples of the central angle to suppress eddy currents, while fixing portions are positioned in the axial direction at the margins of stacked plates. This dimensional separation allows both eddy current suppression and fixing alignment to be achieved independently without conflict.
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 effectively suppresses eddy current loss and maintains geometrical tolerance by aligning coupling and fixing portions, ensuring consistent magnetic distribution and stable operation of the rotary electric machine.
Implementation Method 1
the electromagnetic steel plates are coupled by the coupling portions formed with the pitches, each corresponding to an integral multiple of the central angle by a double pole pitch of the rotor, thereby allowing magnetic distributions among the coupling portions in the stator to be the same regardless of the rotor rotational position
Implementation Method 2
consequently, it is possible to hinder the eddy current from flowing through the stacked electromagnetic steel plates via the coupling portions, thus suppressing generation of the eddy current loss
Data Source
AI summary
A stator and a rotary electric machine include a stator core including a plurality of stacked annular electromagnetic steel plates with coupling portions. The coupling portions are arranged with a pitch of an integral multiple of a central angle. The central angle is defined as an angle between two adjacent magnetic poles of the same polarity relative to a rotational center of the rotor. When a number of the coupling portions is an odd number, fixing portions are arranged with the same pitch as the pitch of the coupling portions, or with a pitch corresponding to a divisor of the pitch of the coupling portions. When a number of the coupling portions is an even number, the fixing portions are arranged with a pitch corresponding to a divisor of the pitch of the coupling portions, or a divisor of 180°.