Rotating Electrical Machine Coil Discharge Prevention
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Solution Overview
Problem
Conventional rotating electrical machines face challenges in preventing electrical discharges between the stator coil and peripheral grounding structures, such as electromagnetic shielding plates, which limits the compactness of the machine design without reducing operating voltage.
Innovation Solution
The implementation of a stator coil structure with a low-resistance layer and a potential grading layer, where the boundary between these layers is positioned farther from the core than the point of closest approach to the electromagnetic shielding plate, along with the use of insulating and prepreg tapes to manage surface resistivity and potential gradients, effectively preventing discharges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the coil end is greatly bent to reduce stator shaft length, then compactness is improved, but discharge risk between stator coil and electromagnetic shielding plate increases
Solution Approach 1:
A potential grading layer is provided on the coil end surface to create a gradual potential distribution from the high-potential coil interior to the grounded shielding plate. This equipotential gradient prevents sudden potential differences that would cause discharge, allowing the coil end to be bent closer to the shielding plate without increasing discharge risk.
Solution Approach 2:
The potential grading layer is specifically applied only to the coil end portion where discharge risk occurs, rather than the entire coil. This localized treatment addresses the specific discharge problem at the coil end while maintaining the effectiveness of the low-resistance layer elsewhere on the coil surface.
2Reliability
If a potential grading layer is provided to prevent discharge, then discharge prevention capability is improved, but device complexity increases
Solution Approach 1:
The potential grading layer is combined with the existing low-resistance layer to form an integrated surface treatment structure. The low-resistance layer provides bulk discharge prevention while the potential grading layer provides surface potential control, and together they create a comprehensive discharge prevention system without requiring completely separate structures.
Solution Approach 2:
The coil surface treatment uses composite material structure with a low-resistance layer (higher bulk conductivity) combined with a potential grading layer (controlled surface resistivity gradient). This composite approach leverages the complementary properties of different material layers to achieve both discharge prevention and compact design.
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 allows for a more compact design by preventing discharges between the coil and shielding plates, enabling a reduced stator shaft length without compromising operating voltage or increasing the risk of extreme discharges.
Implementation Method 1
a low-resistance layer is provided on the surface of a coil to prevent discharge in a slot made between a core and a coil
Implementation Method 2
a potential grading layer is provided at the end of a low-resistance layer to prevent discharge on the surface of the low-resistance layer during operation
Data Source
AI summary
According to one embodiment, there is provided a rotating electrical machine including a core, a coil extending from the core, and an electromagnetic shield which is provided outside the core, and has a plurality of shoulders projecting toward the coil. The coil includes an insulator covering outside of a conductor, a resistance layer formed on a surface of the insulator and contacting the core, and at least one potential grading layer formed on a surface of the insulator adjacent to the resistance layer. A boundary between the resistance layer and potential grading layer is provided at a position farther from the core than a point on a surface of the coil, where a distance between the coil and a shoulder of the electromagnetic shield closest to the core is the shortest.