Traction Transformer Core Mounting for Weight Reduction
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Solution Overview
Problem
Conventional traction transformers for electric railway vehicles are bulky and heavy due to their design requirements, which include accommodating various input frequencies and voltages, and are prone to mechanical stress and electrical failures from dust and humidity, necessitating substantial materials for mechanical stability and insulation.
Innovation Solution
A compact traction transformer design where the transformer core is not in contact with the insulating liquid, allowing direct attachment of mounting means to the core, reducing the amount of insulating liquid and simplifying the mechanical structure, using lightweight materials for the enclosure, and incorporating support elements and stiffening elements to manage mechanical forces and stray magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transformer core is encased in a tank filled with insulating oil, then electrical insulation and heat transfer are improved, but the weight and size of the transformer increase substantially
Solution Approach 1:
The patent divides the transformer into two separate parts: the core (with windings) and the tank (with insulating oil). The core is not encased in the tank but is positioned above it, connected via support elements. This segmentation allows the core to be mounted directly to the vehicle structure, eliminating the need for a heavy steel tank that must bear the core's weight, while the tank still provides necessary electrical insulation and cooling for the windings.
Solution Approach 2:
The patent extracts the core from the traditional oil-filled tank enclosure. Instead of being immersed in oil, the core is positioned above the tank and connected through support elements. This extraction removes the unnecessary structural weight of a thick-walled tank while preserving the essential functions of electrical insulation and thermal management through the oil-filled tank and alternative cooling paths.
2Strength
If a substantial wall thickness and heavy material are used for the tank, then mechanical stability is improved, but the weight increases
Solution Approach 1:
The patent removes the core from the tank enclosure, allowing the tank to be designed without substantial wall thickness. Since the core is mounted separately to the vehicle structure, the tank only needs to contain the insulating oil and provide electrical insulation, not bear mechanical loads. This enables the use of lighter materials and thinner walls while maintaining necessary electrical and thermal functions.
Solution Approach 2:
By separating the core mounting function from the tank structure, the patent allows each component to be optimized independently. The vehicle structure bears the mechanical loads through direct core mounting, while the tank is optimized for its containing and insulating functions, enabling lightweight construction without compromising overall mechanical stability.
3Use of energy by moving object
If the transformer is placed outside the main casing (underfloor or rooftop), then space for ventilation is improved, but the available installation space is limited by vehicle height and ground clearance
Solution Approach 1:
The patent transitions from horizontal placement (underfloor or rooftop) to vertical placement. The core is positioned above the tank in the vertical dimension, allowing the transformer assembly to fit within the vehicle's vertical space envelope. This vertical arrangement optimizes ventilation pathways and utilizes otherwise underutilized vertical space, improving heat dissipation while accommodating installation constraints.
4Device complexity
If dry insulation or air insulation is used, then the structure is simpler, but electrical failures occur frequently due to dust and humidity exposure
Solution Approach 1:
The patent introduces insulating oil as an intermediary substance between the windings and the external environment. The oil-filled tank acts as a protective barrier that excludes dust and humidity from the electrical components, preventing the electrical failures that plague dry-insulated transformers. The support elements and mounting structure serve as additional intermediaries that maintain the separation between the core and the tank while allowing thermal and mechanical interaction.
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 a reduced size and weight while maintaining power density, enhancing mechanical stability and reducing electrical failures, allowing for efficient energy transfer and improved thermal management.
Implementation Method 1
conventional state of the art traction transformers for electric railway propulsion vehicles are by the type of insulation and cooling oil-immersed transformers to meet the requirements. Oil being a very good heat transfer medium and a good electrically insulating material compared to air
Implementation Method 2
Oil being a very good heat transfer medium and a good electrically insulating material compared to air, when a high power density is needed
Implementation Method 3
the traction transformer is a crucial piece in the traction chain... provides energy from the catenary to the propulsion motor and for all on board systems
Data Source
Figure 1~2a
Figure 2b~2c
Figure 2d~3
AI summary
The invention relates to a traction transformer (1) for railbound vehicles comprising: - an insulating liquid filled enclosure (20), - at least two windings (30, 31) contained in the enclosure (20), - a transformer core (40), - mounting means (50) for mounting the transformer (10) to the railbound vehicle, wherein the transformer core (40) is arranged outside the enclosure (20), and wherein the mounting means (50) are attached to the transformer core (40).