Traction Transformer with External Core and Oil-Immersed Windings
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Solution Overview
Problem
Conventional transformers for high-power traction applications are bulky and heavy due to restricted heat dissipation through oil, limiting further size and weight reduction despite the use of oil-filled tanks and forced cooling systems.
Innovation Solution
A transformer design with a core outside the oil-filled enclosure and windings immersed in the oil, utilizing an enclosure with insulating material and conductive components to minimize oil usage, allowing for reduced weight and improved cooling efficiency while avoiding overheating and static charge issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional oil-filled tanks with forced oil circulation are used, then high-power transformation is achieved, but size and weight cannot be further reduced
Solution Approach 1:
The core is extracted from the oil-filled enclosure and positioned externally, with only the legs extending through channels in the enclosure. This separation allows the bulk of the transformer to be outside the oil tank, significantly reducing the oil volume required and thus the overall weight while maintaining high-power transformation capability through the immersed windings
Solution Approach 2:
The transformer is segmented into distinct functional zones: the core located externally with legs passing through channels, the windings immersed in oil within the enclosure, and the isolation material filling the enclosed volume. This segmentation allows optimized cooling and insulation without requiring the entire transformer to be oil-filled
2Weight of stationary object
If the core is placed outside the oil-filled enclosure, then weight is reduced, but insulation and cooling effectiveness may be compromised
Solution Approach 1:
The enclosure with isolation material acts as an intermediary between the external core and the internal windings. The isolation material provides electrical insulation and thermal management for the immersed windings, while the channel structure allows the core legs to pass through without direct oil contact, maintaining both weight reduction and reliability
Solution Approach 2:
The channel structure is nested within the enclosure, creating a protected pathway for the core legs. The windings are nested around the channel interior, immersed in oil for cooling, while the isolation material fills the enclosed volume. This nested arrangement maintains compact dimensions with optimized cooling and insulation
3Weight of stationary object
If oil quantity is reduced, then weight and environmental footprint are reduced, but heat dissipation capability may be limited
Solution Approach 1:
By extracting the core from the oil-filled enclosure and positioning it externally with legs passing through channels, the design minimizes the oil volume required to only what is necessary for winding immersion and cooling, thereby reducing weight while maintaining adequate heat dissipation through the isolated winding-cooling system
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 design achieves reduced weight and environmental footprint with enhanced cooling and reduced risk of overheating and static discharge, enabling high power density and efficient heat transfer.
Implementation Method 1
the enclosure having an enclosed volume filled with isolation material
Implementation Method 2
As oil is a very good heat transfer medium and a good isolation material
Implementation Method 3
transformers are conventionally used for galvanic decoupling and transformation of electrical power
Data Source
AI summary
A transformer which includes an enclosure with a first and second cover arranged at opposite ends of the enclosure, the enclosure having an enclosed volume filled with isolation material and including at least one channel which extends through the enclosure from the first cover to the second cover. The interior of each channel is separated from the enclosed volume, and the core is provided outside of the enclosed volume and comprises a leg and a yoke. The leg extends through the channel. The transformer further includes a coil inside the enclosed volume and being wound about the channel. The first and second cover each comprise an electrically insulating material and at least one electrically conductive component.