Transformer Winding Overlap for Homogeneous Current Distribution
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Solution Overview
Problem
High power resistance spot welding systems face inefficiencies due to non-homogeneous current distribution and high power losses in transformer windings and connections, particularly at high frequencies, which complicates the arrangement and increases weight and cost.
Innovation Solution
A transformer design with partial overlap of primary and secondary windings in the winding heads, combined with complete overlap in the transformer window, allows for homogeneous current distribution and shorter, straight connections, reducing leakage inductances and power losses, and enabling easier cooling and integration of rectifier devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If complete overlap of primary and secondary windings is implemented in the transformer window, then magnetic coupling is improved and leakage inductance is reduced, but the arrangement of connections for output rectifier becomes difficult and current distribution becomes non-homogeneous
Solution Approach 1:
The transformer windings are segmented into distinct regions: complete overlap in the transformer window for optimal magnetic coupling, and partial overlap in the winding heads for simplified connections. This segmentation allows each region to optimize for its specific function without compromising the other.
Solution Approach 2:
Different overlap arrangements are applied to different spatial locations: complete overlap is implemented in the transformer window where magnetic coupling is critical, while partial overlap is implemented in the winding heads where connection accessibility is critical. This local differentiation resolves the contradiction between magnetic efficiency and connection simplicity.
2Weight of stationary object
If higher frequency PWM supply voltage is used, then transformer size and weight are reduced, but current distribution homogeneity becomes more difficult to achieve
Solution Approach 1:
The winding structure is segmented to provide different overlap characteristics in different regions, which helps maintain homogeneous current distribution even at high frequencies by reducing skin effect and proximity effect impacts through the partial overlap configuration in winding heads.
3Loss of energy
If straight connections are used to connect output rectifier, then leakage inductance is reduced and power loss is minimized, but connection surface area on secondary winding is reduced
Solution Approach 1:
The connection arrangement utilizes the spatial dimension created by partial overlap in the winding heads, allowing straight connections to be made while maintaining adequate surface area through the extended winding head structure rather than relying solely on the transformer window space.
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
This design achieves a more efficient and compact transformer with reduced power losses and increased output power, allowing higher frequency operation while simplifying production and cooling, and reducing the complexity and weight of the system.
Implementation Method 1
a primary winding (231) with a number of turns N1 and a secondary winding (233) with a number of turns N2, magnetically connected to each other
Implementation Method 2
reducing leakage inductances and power losses
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Arrangement of a transformer with an output rectifier (30) comprising at least one primary winding (231) that consists of at least one segment made with several turns, wound at a suitable distance around the transformer axis (300), an iron core (236) electrically isolated from said primary winding, at least one secondary winding (233) electrically isolated from said primary winding and said iron core, comprising a first part (234) of said at least one secondary winding and a second part (235) of said at least one secondary winding, wherein both are wound at appropriate distances around the transformer axis (300), between which at least one primary winding coil is arranged, wherein said primary winding and said secondary winding overlap along the axis (500) in a part surrounded by an iron core and further, wherein the said primary winding and the said secondary winding in the part of the winding heads, which are not surrounded by the iron core, overlap only partially or do not overlap, which allows straight and short arrangement of the connections of an output rectifier in the direction of the axis (500). As a result of the proposed transformer arrangement improved electromagnetic properties of the welding system are obtained, which provides a more homogeneous distribution of magnetic field in the iron core and a homogeneous distribution of electric currents in conductive parts, which affects the reduction of transformer power loss and operation with the higher frequency of the supply voltage. The arrangement of the secondary winding according to the present invention at the same time enables a much simpler production of the cooling of the welding transformer with output rectifier by liquid coolant by making bores of the adequate dimensions.