Stator Conductor Weld Geometry for Stronger End Connections
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Solution Overview
Problem
The mechanical fatigue strength of welded joints in stator conductors is compromised due to a small weld cross-section in the height direction, leading to temperature peaks and potential space constraints from raised windings.
Innovation Solution
A welded joint design with a protrusion in the height direction, utilizing a molten weld pool to sink below the conductor ends' edge sections, forming an oval or circular cross-section, and using a laser to create the joint without additional material, ensuring a favorable aspect ratio and insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the welded joint cross-section in the height direction is kept small, then the winding overhang in the axial direction is reduced, but the mechanical fatigue strength of the welded joint deteriorates and temperature peaks occur
Solution Approach 1:
The welded joint is designed to protrude in the width direction (B) beyond the conductor ends, compensating for the reduced height (H) by extending in a different dimension. This dimensional shift maintains mechanical strength while controlling axial overhang.
Solution Approach 2:
The aspect ratio of the welded joint is changed from a small HxB ratio to a larger BxH ratio, where the width B is increased relative to height H. This parameter change allows the joint to achieve sufficient mechanical strength through width extension rather than height extension.
2Strength
If the welded joint protrudes in the height direction, then the mechanical strength increases, but the winding overhang in the axial direction increases
Solution Approach 1:
The welded joint is designed with asymmetric protrusion: it protrudes significantly in the width direction (B) but is constrained in the height direction (H) to not exceed the conductor end height. This asymmetric geometry achieves mechanical strength through width extension while preventing axial overhang.
Solution Approach 2:
Instead of protruding in the height direction (axial dimension), the welded joint protrudes in the width direction (radial dimension). This dimensional redirection maintains mechanical strength while avoiding the problem of increased winding overhang in the axial direction.
3Temperature
If the weld cross-section in the height direction is increased, then temperature peaks at the welded joint are reduced, but the winding overhang in the axial direction increases
Solution Approach 1:
The aspect ratio parameters of the welded joint are optimized: height H is set to at least 0.5mm (sufficient for heat dissipation) while width B is increased to create a BxH ratio greater than 0.5. This parameter optimization reduces temperature peaks through adequate height while controlling axial overhang through constrained height growth.
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
Enhances mechanical strength, reduces temperature peaks, and saves installation space by sinking the joint, while allowing for a high electrical fill factor and uniform insulation coating.
Implementation Method 1
The welded joint (8) is provided on the end faces (6) of the respective conductor ends (5) and is produced by means of a laser and without the use of any additional material
Implementation Method 2
The bilateral protrusion or projection of the welded joint requires material that comes from the molten weld pool and causes the surface of the welded joint to sink in relation to the end faces of the edge sections
Data Source
Figure 1
Figure 2~3
AI summary
A stator of an electrical machine which has stator slots and conductor elements arranged in the stator slots, which conductor elements each have two conductor ends, is already known. A plurality of conductor ends, which are situated next to one another, of different conductor elements are in each case connected to one another by means of a weld connection, which is provided at the end sides of the conductor ends in question, without additional material. The conductor ends which are connected to one another in each case form a common rectangular conductor cross section which has a height H and a width B, wherein the height H corresponds to the height h of an individual cross section of the conductor ends, and the width B of the common conductor cross section is made up of the sum of the widths b of the individual cross sections of the conductor ends. The weld connection is in each case provided, as seen in the direction of the width B, between two non-melted edge sections of the outermost conductor ends. The weld cross section in the direction of the height H is comparatively low, this having effects on the long-term mechanical strength of the weld connection and, during operation of the electrical machine, possibly causing temperature peaks at the weld connection as a result of a high current density. In the case of the stator according to the invention, the mechanical strength of the weld connection is increased. According to the invention, it is provided that the extent (L2) of the weld connection (8) in the direction of the height (H) is greater, at least in sections, than the height (H) of the common conductor cross section (9), and the surface of the weld connection (8) is consequently sunken in relation to the end sides (6) of the edge sections (10).