Rotary Electric Machine Magnet Segmentation for Eddy Current Loss
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Solution Overview
Problem
Conventional rotary electric machines experience significant eddy-current losses in permanent magnets, leading to reduced torque efficiency due to induced currents in the circumferential direction, which affects the overall performance of the machine.
Innovation Solution
The implementation of a slit-like magnet separation portion on the permanent magnet, combined with an insulation layer and strategically designed iron cores with slits, effectively suppresses eddy currents by electrically isolating the magnet and reducing current paths that could bypass the slit, thereby minimizing torque loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a permanent magnet is used in the rotor, then magnetic flux and torque output are improved, but eddy-current loss increases due to induced currents in the circumferential direction
Solution Approach 1:
The permanent magnet is divided into multiple magnet units by providing slits that extend in the axial direction, separating the magnet circumferentially. This segmentation interrupts the eddy current paths while maintaining the magnetic flux generation capability, thus reducing eddy-current loss while preserving torque output.
Solution Approach 2:
An insulation layer is introduced between adjacent magnet units to electrically isolate them. This intermediary layer prevents eddy currents from flowing across the magnet boundaries in the circumferential direction, thereby reducing eddy-current loss while allowing the magnets to remain in close proximity for effective magnetic coupling.
2Loss of energy
If the permanent magnet is separated circumferentially to reduce eddy currents, then eddy-current loss is reduced, but magnetic flux continuity may be affected
Solution Approach 1:
The slits and insulation layers are strategically positioned only where needed to interrupt eddy current paths, while the majority of the magnet structure maintains continuous magnetic properties. This localized modification approach preserves magnetic flux continuity in the radial and axial directions while blocking circumferential eddy currents.
Solution Approach 2:
The magnet assembly becomes a composite structure combining permanent magnet material with non-magnetic slit regions and insulation layers. This composite configuration allows the magnetic components to function together while the non-magnetic elements selectively block eddy current paths without significantly impeding the magnetic flux.
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 significantly reduces eddy current-induced torque loss, enhancing the efficiency and performance of the rotary electric machine by preventing current flow through the magnet and other components, resulting in improved magnetic flux and torque output.
Implementation Method 1
eddy-current losses in a permanent magnet... induced currents in the circumferential direction... effectively suppresses eddy currents by electrically isolating the magnet
Implementation Method 2
combined with an insulation layer and strategically designed iron cores with slits, effectively suppresses eddy currents by electrically isolating the magnet
Data Source
AI summary
A rotary electric machine in an embodiment includes a stator, and a rotor capable of rotating around a rotation center. The rotor includes a first rotor core, a second rotor core, and a magnet. The first rotor core includes first rotor magnetic poles that are arranged being spaced apart from one another in a circumferential direction and that face first stator magnetic poles, and is annular. The second rotor core includes second rotor magnetic poles that are arranged being spaced apart from one another in the circumferential direction and that face second stator magnetic poles, and is annular. The magnet is located between the first rotor core and the second rotor core and provided with a slit-like magnet separation portion that separates at least a part thereof in the circumferential direction, and is annular.