Segmented Thermal Bridge for Electric Machine Heat Dissipation
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Solution Overview
Problem
In electric machines, particularly axial flux machines, the use of low permeability materials for the housing and insulators like epoxy between stator windings and the housing reduces heat transfer due to poor thermal conductivity, leading to inefficient thermal dissipation.
Innovation Solution
A thermal bridge is introduced between the stator core and the housing of the electric machine, formed from a non-magnetic material with high thermal conductivity, comprising individual thermal bridge elements that extend from a base element to increase contact area and reduce eddy currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If low permeability materials are used for the housing to reduce flux leakage, then magnetic flux leakage is reduced, but thermal conductivity deteriorates leading to poor heat transfer
Solution Approach 1:
The thermal bridge is divided into multiple individual thermal bridge elements rather than a single continuous structure. This segmentation reduces eddy current formation while maintaining thermal conduction paths from the stator windings to the housing, effectively resolving the contradiction between reducing flux leakage and improving heat transfer
Solution Approach 2:
The thermal bridge acts as an intermediary component between the stator windings and the housing. It provides a dedicated thermal conduction path that does not rely on the housing material's thermal conductivity, thus enabling effective heat transfer while allowing the housing to maintain its low permeability characteristics for flux leakage reduction
2Reliability
If insulators such as epoxy are used between stator windings and housing to provide electrical insulation, then electrical insulation is improved, but thermal conductivity deteriorates
Solution Approach 1:
The thermal bridge serves as an intermediary that bridges the thermal gap created by electrical insulators. It provides a dedicated thermal conduction path that bypasses the insulating materials, allowing heat to transfer effectively from the stator windings to the housing while maintaining the necessary electrical insulation
Solution Approach 2:
The thermal bridge elements are formed from composite materials or materials with specific properties that provide both thermal conductivity and electrical insulation characteristics, allowing simultaneous achievement of thermal management and electrical isolation functions
3Temperature
If a continuous thermal bridge is used to enhance heat transfer, then thermal conductivity is improved, but eddy currents increase leading to energy loss
Solution Approach 1:
The thermal bridge is segmented into multiple individual elements rather than forming a continuous path. This segmentation interrupts eddy current loops while maintaining sufficient thermal conduction capability, effectively reducing eddy current losses while preserving heat transfer performance
Solution Approach 2:
Different regions of the thermal bridge structure are designed with different properties - the individual elements provide thermal conduction paths while the gaps between elements prevent eddy current formation. This local differentiation of structural quality resolves the contradiction between heat transfer and energy 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
The thermal bridge effectively enhances heat transfer from the stator windings to the housing, improving thermal dissipation without increasing flux leakage, thus maintaining the machine's efficiency and performance.
Implementation Method 1
The thermal bridge is formed from a non-magnetic material with high thermal conductivity
Implementation Method 2
comprising individual thermal bridge elements that extend from a base element to increase contact area and reduce eddy currents
Data Source
AI summary
An electric machine includes a housing having an inner surface; and a stator including a stator core mounted in the housing. The stator core includes a plurality of stator windings, a thermal bridge extends between the stator core and the inner surface of the housing. The thermal bridge is formed from a non-magnetic material and includes a plurality of individual thermal bridge elements.