Disc Rotor Thermal Management via Segmented Materials
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Solution Overview
Problem
Electrical machines with disc rotors face heat generation issues due to eddy currents, leading to increased temperatures and potential demagnetization of permanent magnets, especially in high-temperature environments, where expensive high-coercive magnets are required to maintain magnetic field strength.
Innovation Solution
A disc rotor design using a thermally conductive material between permanent magnets and the rotor shaft, combined with an electrically non-conductive material for the magnets, enhances heat dissipation and reduces eddy current-induced heating without compromising mechanical stability, allowing for the use of less expensive magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If an electrically non-conductive material (plastic) is used for the rotor body, then heat generation from eddy currents is reduced, but heat dissipation capability deteriorates
Solution Approach 1:
The rotor body is segmented into multiple materials with different properties: an electrically non-conductive material (plastic) for the main rotor body to reduce eddy currents, and a thermally conductive material (metal) for the carrier element to improve heat dissipation. This segmentation allows each material to perform its specialized function without compromise.
Solution Approach 2:
The invention uses a composite structure combining electrically non-conductive plastic material and thermally conductive metal material in specific regions. The plastic reduces eddy current losses while the metal carrier element provides thermal conduction path from permanent magnets to rotor shaft, achieving both electrical insulation and thermal management.
2Reliability
If expensive high-coercive permanent magnets are used, then demagnetization resistance is improved, but manufacturing cost increases
Solution Approach 1:
The thermally conductive carrier element acts as an intermediary that actively manages heat away from the permanent magnets. By providing a dedicated thermal conduction path to the rotor shaft, it maintains lower operating temperatures for the magnets, thereby protecting them from thermal demagnetization without requiring expensive high-coercive magnet materials.
Solution Approach 2:
The invention changes the thermal parameter (temperature) of the permanent magnets by introducing active heat dissipation through the carrier element. This parameter change allows the use of less expensive permanent magnets that would otherwise be vulnerable to demagnetization at higher temperatures.
3Temperature
If a thermally conductive material is used between permanent magnets and rotor shaft, then heat dissipation is improved, but eddy current losses may increase
Solution Approach 1:
The thermally conductive material is applied locally only in the carrier element where heat dissipation is needed, while the main rotor body remains electrically non-conductive. This localized application ensures thermal management benefits without introducing significant eddy current losses in the bulk rotor structure.
Solution Approach 2:
The rotor body is segmented into an electrically non-conductive main body and a thermally conductive carrier element. This segmentation allows the carrier element to perform thermal conduction function while the main rotor body maintains electrical insulation properties, minimizing eddy current losses.
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 design effectively reduces heat generation, maintains lower operating temperatures, and improves demagnetization resistance of permanent magnets, ensuring efficient heat dissipation and mechanical stability while using less expensive magnets.
Implementation Method 1
the rotor body has a first material for dissipating heat in the radial direction
Implementation Method 2
Eddy currents can be induced in electrically conductive materials during operation of permanent-magnet electrical machines, which cause heating
Data Source
Figure 1~2b
Figure 3~4b
Figure 5a~7
AI summary
The invention relates to a disc rotor (2, 6, 7) for an electric machine (1), comprising: - a circular or ring-shaped disc-like rotor body (21, 61, 71); - permanent magnets (23, 62, 73) arranged circumferentially adjacent to each other on the rotor body (21, 61, 71); wherein the rotor body (21, 61, 71) has a first material for dissipating heat in the radial direction and a second electrically non-conductive material in the area of the permanent magnets.