Rolled Iron Core Traction Transformer Air Gap Elimination
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Solution Overview
Problem
Conventional traction transformers with laminated iron cores experience high no-load losses, noise, and reduced short-circuit resistance due to air gaps and magnetic domain disruptions, which affect their performance in electrified railways.
Innovation Solution
A rolled iron core traction transformer is designed by splicing symmetrical annealed iron-core closed single frames from continuous silicon steel sheets without air gaps, featuring multiple windings with tapping areas and electrostatic plates, and a cooling separation trough to reduce no-load losses and enhance short-circuit tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a laminated iron core is used with cut and stacked silicon steel sheets, then the transformer can be manufactured, but air gaps are formed at the butt joints increasing no-load losses and no-load current
Solution Approach 1:
The invention changes the fundamental parameter of iron core construction from laminated stacked sheets to a rolled continuous structure. This eliminates the air gaps at butt joints that cause high no-load losses, while maintaining manufacturability through the rolling and splicing process that creates a continuous iron core without discontinuities.
Solution Approach 2:
The invention uses a composite structure combining rolled silicon steel sheets spliced together to form a continuous iron core. This composite approach eliminates the air gaps present in traditional laminated structures while maintaining the beneficial properties of silicon steel, achieving both low no-load losses and manufacturability.
2Ease of manufacture
If a laminated iron core is used with cut and stacked silicon steel sheets, then the transformer can be manufactured, but the cutting and stacking process disrupts magnetic domains increasing no-load losses
Solution Approach 1:
The invention fundamentally changes the manufacturing parameter from cutting and stacking to rolling and splicing. This continuous rolling process preserves the magnetic domain structure of the silicon steel sheets, eliminating the disruption caused by cutting operations while maintaining ease of manufacture through the rolling process.
3Ease of manufacture
If air gaps are present in the iron core, then the transformer can be assembled, but the high magnetic reluctance increases noise
Solution Approach 1:
The invention changes the iron core structure parameter from segmented with air gaps to continuous rolled without air gaps. This eliminates the high magnetic reluctance zones that generate noise, while the spliced rolled structure maintains ease of assembly through the continuous seamless construction.
4Ease of manufacture
If gaps are reserved when loop coils are looped, then the coils can be arranged, but the resistance of short-circuit of the coil decreases
Solution Approach 1:
The invention merges the coil structure into a continuous loop configuration without gaps. This eliminates the discontinuities that reduce short-circuit resistance, while the continuous loop structure maintains ease of arrangement and assembly. The coils are formed as seamless continuous loops that provide both manufacturability and high short-circuit resistance.
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 reduces no-load losses, noise, and improves short-circuit resistance, enabling better performance and mechanical strength in traction transformers by eliminating air gaps and stress in the iron core, and synchronizing voltage regulation.
Implementation Method 1
the iron core is formed by splicing two symmetrical annealed iron-core closed single frames
Implementation Method 2
The air gap, which has high value of magnetic reluctance, is formed in the butt joint of the silicon steel, so that no-load losses and no-load current are increased
Implementation Method 3
The process of cutting and stacking the silicon steel, which also makes the no-load losses increasing, will affect the arrangement of magnetic domains
Implementation Method 4
on the both ends of the low voltage F winding and the high voltage winding are provided with electrostatic plates
Implementation Method 5
a cooling separation trough is provided between two iron-core closed single frames for lower the iron-core temperature and enhance over-excitation
Implementation Method 6
each iron-core column is sequentially provided with a low voltage T winding, a low voltage F winding and a high voltage winding thereon
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A rolled iron core traction transformer, comprising an iron core (1); the iron core (1) is formed by splicing two symmetrical annealed iron-core closed single frame (1-1) ; each iron-core closed single frame (1-1) is formed by sequentially coiling continuous silicon steel sheets; the iron-core closed single frame (1-1) has two iron-core column single bodies (1-1-1),which having approximately semicircular cross sections; the iron core (1) has two iron-core columns (1-2), which have approximately circular cross section, thereon formed by splicing two iron-core column single bodies (1-1-1) ; each iron-core column (1-2) is sequentially provided with a low-voltage T winding (6), a low voltage F winding (5) and a high-voltage winding (4) thereon from inside to outside; two sides of each high-voltage winding (4) are respectively provided with a first tapping area and a second tapping area, the first tapping area is provided with low-voltage side high-voltage tapping outgoing lines (16), the second tapping area is provided with high-voltage side high-voltage tapping outgoing lines (18), two low-voltage side high-voltage tapping outgoing lines (16) are connected together with a no-load voltage regulation switch (9), and two high-voltage side high-voltage tapping outgoing lines (18) are connected together with another no-load voltage regulation switch (9).The transformer has a significant the improvement such as a reduced no-load loss, a reduced no-load current, lower noise , stronger anti-short circuitcapability, a reduced electrodynamic force generated by a sudden short circuit, and a improvement of the short circuit tolerance capability of the transformer.