Winding Overhang Support for Electrical Machines
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Solution Overview
Problem
Existing support systems for winding overhangs in electrical machines, particularly in high-power variable-speed applications, fail to adequately address the challenge of providing radial support against centrifugal forces while maintaining effective cooling, as they often disrupt ventilation slots and introduce mechanical stresses.
Innovation Solution
A dual-ring system where an outer ring is shrunk onto the winding bars and an inner ring forms a composite with them, both rings being axially distant from the laminated core, allowing for unhindered radial expansion and movement, with spacers and insulating inserts to manage stress and facilitate cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rotor cap is shrunk onto the rotor body to support the end winding radially, then radial support against centrifugal forces is improved, but ventilation slots are closed and cooling is disrupted
Solution Approach 1:
The support structure is divided into two separate rings (inner ring and outer ring) that are axially spaced from the laminated core, rather than using a single cap structure. This segmentation allows the support function to be provided without blocking the ventilation slots, thus maintaining cooling effectiveness while providing radial support against centrifugal forces.
Solution Approach 2:
The support rings are positioned at an axial distance from the laminated core, moving the support function to a different spatial dimension (axial direction) rather than using a radial cap structure. This dimensional change allows ventilation slots to remain open while still providing the necessary radial support for the end windings.
2Strength
If the end winding is rigidly fixed to prevent radial movement, then radial support is improved, but bending and shearing stresses on winding bars increase
Solution Approach 1:
The inner ring and outer ring are designed to allow controlled radial movement and expansion. The rings can expand radially unhindered and the composite structure can move freely in the radial direction, providing dynamic adaptation to centrifugal forces rather than rigid constraint, thus reducing bending and shearing stresses on the winding bars.
Solution Approach 2:
The dimensional and material parameters of the composite structure (inner ring, winding bars, outer ring) are carefully selected to ensure that radial relative movements remain low at standstill and in all operating states, while allowing sufficient movement to prevent excessive stresses. This parameter optimization balances support stability with stress reduction.
3Stress or pressure
If spacers are added to prevent radial shrinkage forces on winding bars, then stress on winding bars is reduced, but device complexity increases
Solution Approach 1:
The spacers serve multiple functions: they prevent radial shrinkage forces on the winding bars, provide structural support between the inner and outer rings, and maintain proper spacing and alignment. By making the spacer multi-functional, the increase in device complexity is minimized while achieving multiple beneficial effects simultaneously.
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 configuration ensures sufficient radial support against centrifugal forces, minimizes mechanical loading on winding bars, and maintains effective cooling by allowing free radial movement and air passage, thereby reducing bending and shearing stresses and ensuring consistent cooling.
Implementation Method 1
an outer ring (10) and an inner ring (12) in the area of the winding overhang (7), between which the winding bars (5, 6) can be arranged in the area of the winding overhang (7), the outer ring (10) being shrunk onto the winding bars (5, 6) and the inner ring (12)
Data Source
Figure 1~2
Figure 3
AI summary
The winding overhang of the rotor of an electrical machine is subject to strong centrifugal forces during operation, especially when the machines run at high speed. The aim of the invention is therefore to devise a winding overhang support which prevents the production of relative movements between the winding overhang and the rotor base, said relative movements resulting in strong mechanical stresses on the winding bars. The invention relates to a winding overhang support which consists of an inner ring (12) and an outer ring (10) between which the winding bars (5, 6) are arranged in the region of the winding overhang (7), the outer ring (10) being shrunk on the inner ring (12) and both the outer ring (10) and the inner ring (12) being interspaced from the lamination stack (3).