Stator Insulating Members for Rotary Electric Machine Leakage Current
Solution Overview
Problem
Existing stators for rotary electric machines face issues with leakage current due to stray capacitance, as previous solutions either deform insulating materials or reduce the insulation distance, leading to increased stray capacitance and impaired product quality.
Innovation Solution
A stator design featuring a core with annularly combined core pieces, shoe portions, and insulating members that include end surface insulators and slot insulators, ensuring a consistent insulation distance without deforming the insulating material, thus maintaining the insulation coat and reducing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the distance between the coil and the stator core is increased to reduce leakage current, then leakage current is reduced, but the area for windings is reduced, causing the space factor of the coil to decrease
Solution Approach 1:
The insulating material is made thinner only at specific locations where sufficient insulation is achieved through structural design (such as increased distance in other areas or improved insulation barriers), rather than uniformly thinning the insulation throughout. This allows maintaining adequate insulation distance to reduce leakage current while preserving winding space in critical areas.
Solution Approach 2:
The thickness of the insulating material is optimized by changing the parameter of insulation distance - using the minimum necessary thickness that still achieves the required insulation performance. This reduces the space occupied by insulation, thereby increasing the space factor for windings while still controlling leakage current within acceptable limits.
2Productivity
If the insulating material is made thinner to increase the space factor of the coil, then the space factor increases, but the insulation distance is reduced, causing leakage current to increase
Solution Approach 1:
Different regions of the insulating structure are designed with different thickness characteristics - the insulating material is thin in areas where it does not compromise insulation performance, but maintains adequate thickness in critical insulation zones. This localized differentiation allows maximizing space factor while preventing leakage current increase.
Solution Approach 2:
The insulation system uses composite structures combining multiple materials or layers with different properties - such as combining thin insulating material with high-permittivity barriers or multiple layers of different thicknesses. This composite approach achieves adequate insulation with reduced overall insulation thickness, thereby increasing space factor while controlling leakage current.
3Ease of manufacture
If the end of the insulating material is deformed by winding tension, then the position of the coil moves to the tooth side, but the distance between the coil and the stator core is shortened, causing leakage current to increase
Solution Approach 1:
The insulating material is designed with preliminary cushioning features such as extended margins, reinforcement zones, or protective coatings at the ends that will be subjected to winding tension. This beforehand preparation prevents deformation during the winding process, maintaining the designed insulation distance and preventing leakage current increase while still allowing the winding process to proceed.
Solution Approach 2:
An intermediary protective layer or reinforcement structure is introduced at the ends of the insulating material to mediate between the winding tension and the insulating material. This intermediary element absorbs or distributes the tension, preventing direct deformation of the insulating material and maintaining adequate insulation distance despite the winding process.
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
The design effectively maintains the insulation distance between the coil and stator core, preventing leakage current increase, ensuring product performance and quality while reducing costs.
Implementation Method 1
a stray capacitance occurs between a stator core and a coil of the rotary electric machine
Implementation Method 2
Leakage current due to the stray capacitance becomes a problem
Data Source
AI summary
Two types of insulating members, i.e., end surface insulators and slot insulators are provided. On tooth portion sides of both side surfaces in the circumferential direction of tooth end surface covering portions of the end surface insulator, first cutouts recessed in the circumferential direction are provided so as to extend in the radial direction. A part axially upward of the first cutouts protrudes in the circumferential direction to form a first overhang portion, and the slot insulator is accommodated between the first overhang portions of two end surface insulators.