Rotor Magnet Insulating Film Placement for Eddy Current Reduction
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Solution Overview
Problem
Existing rotor configurations for rotating electric machines with magnets inserted into magnet holes in a rotor core face challenges in reducing eddy current loss and cost while stabilizing magnet position, as they often require extensive electric insulating films that increase complexity and cost.
Innovation Solution
A rotor configuration where only specific surfaces of the magnets are covered with electric insulating films, allowing for reduced contact points with the rotor core and the use of positioning members to prevent movement, thereby minimizing eddy current loss and cost while maintaining stable magnet positioning without the need for resin fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If electric insulating films are applied to entire surfaces of magnets, then eddy current loss is reduced, but manufacturing cost increases
Solution Approach 1:
The patent applies electric insulating films only to specific local areas of the magnet surfaces (radial surfaces at both ends in the axial direction) rather than entire surfaces. This localized application reduces the amount of insulating material required and simplifies the coating process, thereby reducing manufacturing cost while still effectively interrupting eddy current paths to reduce eddy current loss.
2Ease of manufacture
If electric insulating films are omitted from magnet surfaces, then manufacturing cost is reduced, but magnet position stability deteriorates
Solution Approach 1:
The patent strategically applies insulating films only to radial surfaces at both ends in the axial direction, leaving other surfaces (such as circumferential surfaces) without films. This allows cost reduction through minimized film application while the presence of films at critical radial contact points maintains sufficient position stability by preventing magnet displacement during operation.
Solution Approach 2:
Instead of applying insulating films to all surfaces (excessive action), the patent applies films only to the minimum necessary surfaces (partial action) - specifically the radial surfaces at both ends. This partial application is sufficient to achieve position stability while significantly reducing manufacturing cost compared to full-surface coating.
3Stability of the object's composition
If magnets are fixed with resin, then position stability is improved, but eddy current loss increases
Solution Approach 1:
The patent extracts and eliminates the resin fixation method from the system. Instead of using resin to fix magnets, the invention relies on direct mechanical fitting of magnets into magnet holes with precise dimensional tolerances. This extraction of resin eliminates the harmful effect of resin-induced eddy currents while maintaining magnet position stability through precision mechanical design.
Solution Approach 2:
The patent replaces the resin fixation method (which causes eddy current loss) with a simpler, more efficient mechanical fitting approach. The precision-machined magnet holes and magnets create a self-retaining structure that provides sufficient stability without requiring additional fixation materials, thereby eliminating the source of eddy current loss.
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 reduces eddy current loss and costs by minimizing electric insulating film usage and employing positioning members to stabilize magnet position, enhancing the efficiency and economic viability of the rotor design.
Implementation Method 1
increase in loss of the rotating electric machine can be reduced even when the eddy current occurs in the magnets
Data Source
AI summary
A rotor for a rotating electric machine includes: a rotor core having magnet holes; magnets inserted in the magnet holes of the rotor core. Each of the magnets includes two first surfaces respectively facing outward and inward of the rotor radial direction, and two second surfaces respectively facing one side and the other side of the rotor circumferential direction. Both ends in the rotor axial direction of at least one first surface of the two first surfaces are covered with electric insulating films, and a lateral surface region between both ends of the one first surface that are covered with the electric insulating films, and the two second surfaces are covered with no electric insulating films.