Stator Slot Insulation Layout to Suppress Coil Eddy Currents
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Solution Overview
Problem
In motor-driven compressors, leakage magnetic flux generates eddy currents in the stator coils, leading to heat generation and reduced output due to the flow of magnetic flux through the spaces between adjacent coils.
Innovation Solution
The inclusion of insulating members in the slots between the teeth and flanges of the stator core, positioning the coils radially outward of the boundaries between the tooth side surfaces and flange surfaces, prevents leakage magnetic flux from flowing through the coils, thereby suppressing eddy current generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If coils are positioned on flange surfaces to maximize space utilization, then the device complexity is reduced, but eddy currents are generated causing heat and energy loss
Solution Approach 1:
An insulating member is introduced as an intermediary element between the flange surface and the coil. This insulating member prevents direct contact between the coil and the conductive flange surface, thereby blocking the leakage magnetic flux path that would otherwise induce eddy currents in the coil, while still allowing the coil to be positioned in the slot for space utilization.
Solution Approach 2:
The harmful function of the flange surface (conducting leakage magnetic flux that induces eddy currents) is extracted by removing its electrical conductivity at the coil interface through the insulating member. The flange surface retains its structural support function while its harmful electrical conduction function is eliminated at the critical interface.
2Loss of energy
If insulating members are added to prevent leakage magnetic flux, then eddy current loss is reduced, but device complexity increases
Solution Approach 1:
The insulating member is designed to perform multiple functions simultaneously: it provides electrical insulation to block leakage magnetic flux, mechanically supports the coil in the slot, and maintains the structural integrity of the stator core. This multi-functionality reduces the need for additional separate components.
Solution Approach 2:
The insulating member combines several functions into a single component: electrical insulation, mechanical support, and structural maintenance. By merging these functions into one element rather than using separate components, the overall device complexity is minimized while achieving the desired effect of reducing eddy current loss.
3Temperature
If coils are positioned radially outward to avoid leakage magnetic flux, then heat generation is reduced, but the volume of the stator increases
Solution Approach 1:
The leakage magnetic flux that would normally cause harm (eddy currents and heat) is redirected by the insulating member to flow along the flange surface instead of through the coil. This converts the harmful flux path into a beneficial one that maintains magnetic circuit integrity while avoiding the coil, thus reducing heat generation without requiring increased stator volume.
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 effectively reduces heat generation in the coils, enhances the stator's efficiency, and allows for a more compact design by minimizing the size of the motor-driven compressor while maintaining effective insulation and heat dissipation.
Implementation Method 1
leakage magnetic flux may be generated that flows from the inner circumferential surface of the yoke toward the flanges of the teeth after passing through the spaces between the coils
Implementation Method 2
The leakage magnetic flux generates eddy currents in the coil, causing the coil to generate heat
Implementation Method 3
An insulating member is arranged in each of the slots. The insulating member is configured to support the corresponding coils
Data Source
AI summary
A stator for a rotating electric machine includes a stator core that includes multiple teeth extending from an inner circumferential surface of a cylindrical yoke, and multiple coils respectively provided around the respective teeth. A slot exists between teeth that are adjacent to each other in a circumferential direction of the yoke. The teeth each include a tooth extension having tooth side surfaces, which define the slots, and two flanges having flange surfaces that define the slots. An insulating member is arranged in each slot. The insulating members are each configured to support the corresponding coils in a state in which each coil is arranged at a radially outer side of a boundary between the corresponding tooth side surface and the corresponding flange surface.