Stator Slot Shielding Segmentation for Parasitic Current Suppression
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Solution Overview
Problem
The complex geometry of slot closure elements in electrical machines increases production costs and requires individual adaptation, while existing electrostatic shielding in winding slots is inefficient due to parasitic currents caused by magnetic field induction.
Innovation Solution
The use of a shielding element as a coating, layer of paint, foil, or metal sheet, arranged in a manner that minimizes short-circuiting of the stator core, either by arranging multiple shielding elements in series or using a strip-shaped element with webs connected to the stator core, effectively reducing parasitic currents and maintaining a strong shielding effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex geometric slot closure element is used, then the shielding effect is improved, but the manufacturing cost increases and individual adaptation to slot shapes is required
Solution Approach 1:
The slot closure element is divided into two separate components: a simple geometric support element and a shielding element with coating, paint layer, film, or sheet. This segmentation allows the support element to be universally applicable to different slot shapes while the shielding element provides the necessary electromagnetic shielding, thereby reducing manufacturing costs and eliminating the need for individual adaptation.
Solution Approach 2:
The support element is designed with a universal geometry that can be applied to various slot shapes without modification. The shielding element is then attached to this universal support structure, making the entire slot closure system adaptable to different slot configurations without requiring custom-designed closure elements for each slot type.
2Reliability
If a continuous shielding element is used, then the shielding effect is improved, but parasitic currents are generated due to short-circuiting of the stator core
Solution Approach 1:
The continuous shielding element is divided into multiple discrete shielding segments along the axial direction of the stator core. These segments are electrically isolated from each other, preventing the formation of continuous eddy current paths through the stator core while maintaining electromagnetic shielding effectiveness in the radial direction.
Solution Approach 2:
The shielding elements are positioned specifically in the slot openings where electromagnetic shielding is most needed, rather than providing continuous coverage. This localized shielding approach maintains the shielding effect where it is most critical while minimizing the creation of parasitic current paths through the stator core.
3Loss of energy
If multiple shielding elements are arranged in series, then parasitic currents are reduced, but the shielding effect is weakened due to gaps between elements
Solution Approach 1:
The shielding elements utilize thin conductive coatings, paint layers, films, or sheets that can provide effective electromagnetic shielding despite their thinness. These thin film structures maintain shielding effectiveness even when arranged in discrete segments, as the thin continuous nature of the coating provides adequate barrier properties while allowing gaps between segments to prevent parasitic currents.
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 reduces production costs, simplifies the application process, and significantly suppresses parasitic currents caused by magnetic field induction while maintaining an adequate shielding effect, even with interruptions between shielding elements.
Implementation Method 1
Motors with electrostatic shielding in the winding slots are also known from JP2006262545 and US5779087
Implementation Method 2
the parasitic current generated by magnetic field induction is kept sufficiently small
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A rotor of an electric machine is already known, comprising a rotor core assembly having a rotor shaft and having slots provided in the rotor core assembly, in which electrical conductors of an electric winding are arranged and which are each sealed by a slot sealing element, each of which comprises an electrically insulating carrier element and a shielding element arranged on the carrier element and made from electrically conductive material. It is a disadvantage that the design of the slot sealing element is geometrically very complex. This leads to increased production costs and to the requirement for individual adjustment of the slot sealing element to the respective slot shape. The insulation of the electrically conductive material functions exclusively for the insulation with respect to the electrical winding. For the stator according to the invention, the respective assembly space required for the slot sealing element in the slots is reduced. According to the invention, the at least one shielding element (6.2) of one of the slot sealing elements (6) is a coating, a lacquer layer, a film or a sheet.