Electric Motor Rotor Retaining Structure for Eddy Current Reduction
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Solution Overview
Problem
The generation of eddy currents on metal retaining bodies in electric motors due to changes in magnetic flux leads to energy loss, as existing metal retaining bodies are conductive and prone to generating eddy currents.
Innovation Solution
A rotor design featuring a retaining body with a truss structure formed by annular and connecting members, where the connecting members are inclined and arranged to reduce eddy current paths and increase structural strength, and optionally filled with small magnets in gaps to enhance electromagnetic force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal retaining body is used to hold the rotating element, then the structural strength is improved, but eddy current is generated leading to energy loss
Solution Approach 1:
The retaining body is divided into multiple annular members arranged at intervals in the axial direction, with connecting members joining them circumferentially. This segmentation interrupts the continuous conductive path, reducing eddy current loops while maintaining structural integrity through the distributed arrangement of members.
Solution Approach 2:
The connecting members are arranged in the circumferential direction between adjacent annular members, creating localized connections that provide structural strength where needed while minimizing the overall conductive area exposed to changing magnetic flux, thereby reducing eddy current generation.
2Ease of manufacture
If the retaining body is formed as a continuous metal structure, then manufacturing simplicity is improved, but eddy current paths are increased leading to higher energy loss
Solution Approach 1:
The retaining body is divided into multiple annular members arranged at intervals in the axial direction, with connecting members joining them circumferentially. This segmentation interrupts the continuous conductive path, reducing eddy current loops while maintaining structural integrity through the distributed arrangement of members.
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 truss structure localizes and reduces eddy currents, minimizing energy loss and enhancing the structural strength of the retaining body, while the additional magnets improve torque and stability of the electric motor.
Implementation Method 1
eddy current is formed on the surface of the retaining body due to a change in magnetic flux generated between the retaining body and a stator
Implementation Method 2
In order to prevent a magnet from being damaged by a centrifugal force of high rotation, a retaining ring (retaining body) formed of Inconel or titanium is attached to an outer peripheral side of the magnet
Data Source
AI summary
A rotor for an electric motor includes: a rotating element extending along an axis; and a retaining body formed of metal and configured to hold the rotating element from an outer peripheral side, where the retaining body includes: a plurality of annular members annularly surrounding an outer peripheral surface of the rotating element and arranged at intervals in the axis direction; and a plurality of connecting members arranged in a circumferential direction between the annular members adjacent to each other so as to connect the annular members. As a result, a path of eddy current is limited and the eddy current can be reduced.