Insulation Element for High-Voltage Railway Cooling
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Solution Overview
Problem
Conventional electrical insulation and cooling systems fail to provide adequate insulation and thermal performance for electrical devices exposed to high voltages, such as those found in railway traction chains, where components must withstand voltages up to 60 kV for extended periods, leading to thermomechanical stresses and poor thermal performance.
Innovation Solution
An electrical insulation element comprising a heat pipe cooling system with an insulating layer made of compacted hexagonal boron nitride or a composite of hexagonal boron nitride and aluminum nitride, integrated with a conductive section to manage dielectric stresses and facilitate heat transfer, ensuring effective electrical insulation and thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional insulating substrate is used to provide electrical insulation between the electrical circuit and the cooling member, then electrical insulation is achieved, but thermal performance deteriorates due to poor heat evacuation
Solution Approach 1:
The insulation element is divided into multiple functional layers: a first insulating layer in direct contact with the electrical circuit for electrical isolation, a heat transfer layer with high thermal conductivity for efficient heat evacuation, and a second insulating layer for additional insulation. This segmentation allows each layer to optimize its specific function, resolving the contradiction between electrical insulation and thermal performance.
Solution Approach 2:
The insulation element uses composite material structures combining different materials with complementary properties: insulating materials (such as ceramic composites, aluminum nitride, or boron nitride) for electrical isolation and heat transfer materials (such as copper or aluminum) for thermal management. This composite approach enables simultaneous achievement of electrical insulation and effective heat evacuation.
2Reliability
If the insulating substrate thickness is increased to withstand higher voltages, then electrical insulation reliability improves, but thermomechanical stresses increase causing deformation
Solution Approach 1:
Instead of using a single thick insulating layer, the solution segments the insulation function across multiple thinner layers with different material properties. The first insulating layer provides voltage withstand capability, while the heat transfer layer manages thermal stresses, and the second insulating layer provides additional insulation. This segmentation reduces thermomechanical stresses compared to a single thick layer while maintaining electrical insulation reliability.
Solution Approach 2:
The invention changes the material parameters of the insulating layers, using materials with high dielectric strength and appropriate mechanical properties. By selecting materials such as ceramic composites, aluminum nitride, or boron nitride with optimized thicknesses and thermal conductivities, the system can withstand high voltages while minimizing thermomechanical deformation.
3Temperature
If a cooling member is placed in direct contact with the electrical circuit for efficient heat transfer, then thermal performance improves, but electrical insulation is compromised
Solution Approach 1:
The cooling system is segmented into distinct functional zones: the first insulating layer maintains electrical isolation between the electrical circuit and the cooling member, while the heat transfer layer provides thermal coupling. This allows the cooling member to be thermally efficient without compromising electrical insulation, as the insulating layers prevent direct electrical contact while the heat transfer layer ensures effective heat evacuation.
Solution Approach 2:
The insulation element acts as an intermediary structure between the electrical circuit and the cooling member. It includes a heat transfer layer that mediates thermal energy transfer while insulating layers mediate electrical isolation. This intermediary structure enables simultaneous achievement of efficient heat transfer and reliable electrical insulation.
4Weight of stationary object
If switching frequency is increased to reduce transformer size, then weight reduction is achieved, but voltage stress on insulation increases requiring thicker insulating layers
Solution Approach 1:
The insulation element uses composite materials with high dielectric strength and optimized thermal conductivity to withstand the increased voltage stress from high-frequency switching. Materials such as ceramic composites, aluminum nitride, or boron nitride provide the necessary electrical insulation reliability while maintaining compact dimensions, enabling the overall system weight reduction achieved by high-frequency operation.
Solution Approach 2:
The invention optimizes the thickness and material parameters of the insulating layers to match the voltage stress conditions of high-frequency operation. By carefully selecting material properties and layer thicknesses, the system can withstand higher voltages without requiring excessive insulation thickness, thus maintaining the weight benefits of high-frequency switching while ensuring insulation reliability.
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 solution enables electrical devices to withstand continuous exposure to 60 kV alternating voltage while maintaining satisfactory thermal performance, reducing dielectric stresses and enhancing cooling efficiency through the use of a heat pipe and insulating materials.
Implementation Method 1
The cooling system comprises a heat pipe extending along a longitudinal axis between a hot end arranged inside the insulation element and a cold end arranged outside the insulation element and in heat exchange relationship with the heat exchanger
Implementation Method 2
The conductive section promotes heat transfer between the electrical device and the heat pipe
Implementation Method 3
an insulating material layer arranged around at least part of the hot end of the heat pipe and in contact with the conductive section, the insulating material layer being formed from a material electrically insulating
Implementation Method 4
a heat exchanger arranged in communication with the cold end of the heat pipe and configured to cool the heat pipe
Implementation Method 5
configured to cool the heat pipe by heat exchange with the outside
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
This insulation element (22) between a device comprising a circuit connected to a catenary and a cooling element (20) for the device includes: a conductive section (36) extending along a longitudinal axis (A-A') and being applied against the device; at least one insulation section (32, 34) attached to the conductive section; and a layer (38) of insulating material (40) applied to the conductive section. The conductive section includes on a wall (64A, 64B) a rim (66A, 66B) defining a zone (70A) of progressive penetration of the insulation section (32, 34) into contact with the conductive section and the layer (38), the zone of progressive penetration defining a junction interface (72A) between the insulation section (32, 34), the conductive section (36) and the layer (38), and being configured to allow a release of dielectric stresses at the junction interface.