Rotary Electric Machine Rotor Leakage Flux Equalization
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Solution Overview
Problem
Conventional synchronous motors experience rotation fluctuations and unbalance of force due to non-uniform leakage flux between magnetic poles, leading to vibrations and torque imbalance.
Innovation Solution
A rotary electric machine design featuring a rotor with alternating magnetic poles formed by stacked electromagnetic steel plates, incorporating short circuit magnetic paths and protruding portions to equalize leakage flux, ensuring balanced magnetic flux distribution and torque contribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional stacked core members are used with connection portions connecting only same-polarity pieces, then magnetic poles are prevented from short-circuiting, but non-uniform leakage flux occurs between magnetic poles causing rotation fluctuation and force unbalance
Solution Approach 1:
A non-magnetic substance is introduced as an intermediary material at the connection portion between magnetic pole pieces of different polarities. This non-magnetic substance acts as a flux barrier that prevents leakage flux from flowing directly between adjacent magnetic poles of opposite polarity, thereby equalizing the leakage flux distribution across all magnetic poles while maintaining the structural connection function.
Solution Approach 2:
The connection portion is designed with non-uniform magnetic properties by selectively applying non-magnetic substances only at specific locations where different-polarity magnetic pole pieces connect. This creates local quality differentiation where the connection portion has different magnetic characteristics compared to the bulk magnetic pole pieces, specifically reducing leakage flux paths at critical interfaces.
2Stability of the object's composition
If rotational stacking is applied to equalize leakage flux, then some uniformity is achieved, but differences in leakage flux amount remain in the rotation axis direction and on the same stack plane
Solution Approach 1:
The non-magnetic substance serves as a compensatory intermediary that addresses leakage flux non-uniformity regardless of stacking alignment variations. By placing this flux barrier at the connection portions, the design compensates for inherent non-uniformities that arise from rotational stacking imperfections in both the rotation axis direction and on the same stack plane.
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 design effectively reduces rotation fluctuations and unbalance of force, improving the rotor's stability and reducing noise and vibration, while allowing for uniform magnetic flux distribution and enhanced torque output.
Implementation Method 1
a short circuit magnetic path mutually connecting at least one set of magnetic pole pieces which form the magnetic poles, respectively
Implementation Method 2
a protruding portion held in contact with an inner circumferential side of each of the permanent magnets, which is positioned between the magnetic pole pieces which are not connected to the short circuit magnetic path
Implementation Method 3
magnetic poles arranged so as to have different polarities alternately, the magnetic poles being excited by permanent magnets which are respectively housed in a plurality of gaps
Data Source
AI summary
Provided is a rotary electric machine, including: a stator; and a rotor provided on the stator so as to be rotatable about a rotation shaft, in which the rotor includes, at an outer circumference thereof, magnetic poles arranged so as to have different polarities alternately, the magnetic poles being formed of a rotor core in which electromagnetic steel plates are stacked, the magnetic poles being excited by permanent magnets which are housed in gaps disposed at an outer circumferential part of the rotor core, and in which the rotor core includes, at an inner circumferential part thereof, in the same stack plane: a short circuit magnetic path connecting magnetic pole pieces which form the magnetic poles; and a protruding portion held in contact with the permanent magnets, which is positioned between magnetic pole pieces which are not connected to the short circuit magnetic path.