Magnetic Pole Piece Rotor Voids to Cut Eddy Current Loss
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Solution Overview
Problem
Magnetic geared rotating machines experience eddy current losses in magnetic pole pieces, which affect the magnetic paths of stator magnets, necessitating a solution that minimizes these losses while preserving magnetic path integrity.
Innovation Solution
The design includes magnetic pole pieces with specific radial cross-sectional configurations featuring inner edges and voids that extend eddy current paths, maintaining minimal impact on stator magnets, with the first distance between the outer face and void being shorter than the distance between the inner face and void, thereby reducing eddy currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a magnetic pole piece is used to modulate magnetic flux, then torque transmission is enabled, but eddy current loss increases
Solution Approach 1:
The magnetic pole piece is segmented by forming voids (through-holes or blind holes) within its structure. These voids divide the continuous magnetic pole piece into multiple regions, interrupting the eddy current paths and reducing eddy current losses while maintaining the torque transmission function through the magnetic flux modulation capability of the segmented structure
Solution Approach 2:
The magnetic pole piece is designed with a porous structure containing multiple voids distributed within its body. This porous configuration allows the magnetic flux to pass through while creating discontinuities that break eddy current loops, thereby reducing energy losses without compromising the magnetic pole piece's ability to transmit torque
2Loss of energy
If voids are formed in magnetic pole pieces to reduce eddy current, then eddy current loss decreases, but magnetic path integrity may be affected
Solution Approach 1:
The voids are strategically positioned and sized to create local discontinuities that interrupt eddy currents without significantly affecting the overall magnetic flux path. The magnetic pole piece maintains sufficient magnetic conductivity in the regions between voids to ensure reliable magnetic coupling and torque transmission
Solution Approach 2:
The voids are designed with specific geometric characteristics (such as being elongated in certain directions or positioned asymmetrically) to preferentially interrupt eddy current paths while minimizing interference with the magnetic flux distribution, thereby reducing eddy current losses without compromising magnetic path integrity
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 losses while ensuring minimal interference with the magnetic paths, enhancing the efficiency and performance of the magnetic geared rotating machine.
Implementation Method 1
a magnetic flux generated from the permanent magnets of the internal rotor is modulated by the magnetic pole pieces. The external rotor is rotated by the modulated magnetic field and the magnetic field of the stator magnets
Implementation Method 2
If the internal rotor rotates due to a rotating magnetic field generated in response to a three-phase alternating current flowing in the windings, a magnetic flux generated from the permanent magnets of the internal rotor is modulated by the magnetic pole pieces
Implementation Method 3
During operation of a magnetic geared rotating machine, if an axially flowing magnetic flux passes through a magnetic pole piece, an eddy current flows in the magnetic pole piece, resulting in an eddy current loss
Data Source
AI summary
A magnetic geared rotating machine, includes: a stator which includes a plurality of stator magnets arranged so as to be aligned in a circumferential direction; a rotor which includes a plurality of rotor magnets arranged so as to be aligned in the circumferential direction, and in which the number of magnetic poles of the plurality of rotor magnets is less than the number of magnetic poles of the plurality of stator magnets; and a magnetic pole piece rotor which includes a plurality of magnetic pole pieces arranged so as to be aligned in the circumferential direction at a radial position between the stator and the rotor.