Stator Slot Winding Layout to Reduce AC Losses
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Solution Overview
Problem
Modern electric motors experience significant AC losses due to the skin effect and proximity losses, particularly near the inner diameter of the slots, leading to inefficient operation, and existing winding arrangements either increase manufacturing costs or fail to effectively limit these losses.
Innovation Solution
A stator winding arrangement with a combination of large and small cross-sectional area wires is used, where large wires are positioned near the outer diameter and small wires near the inner diameter, forming parallel paths with balanced conductors to reduce AC losses without increasing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If large copper wire is used in the stator winding, then DC resistance is limited, but AC losses increase due to skin effect and proximity losses
Solution Approach 1:
The patent applies local quality by using different wire sizes in different locations within the slot. Large cross-sectional area wire is used in the back of the slot (near OD) where DC resistance is the primary concern, while small cross-sectional area wire is used in the front of the slot (near ID) where AC losses from skin effect and proximity losses are most significant. This spatial variation in wire properties optimizes both DC and AC performance.
2Loss of energy
If small copper wire is used to limit AC losses, then AC resistance is reduced, but DC resistance increases
Solution Approach 1:
The patent implements local quality by strategically placing small cross-sectional area wire in the front of the slot where AC losses dominate, and large cross-sectional area wire in the back of the slot where DC resistance is the primary concern. This localized differentiation allows the winding to simultaneously minimize both AC and DC resistance in their respective critical regions.
3Loss of energy
If mixed wire sizes are used in the stator winding, then AC losses are limited, but manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the slot into two distinct regions: the back of the slot (near OD) and the front of the slot (near ID). Each region is filled with wire of appropriate cross-sectional area for its specific electrical performance requirements. This segmentation allows mixed wire sizes to be systematically arranged without excessive manufacturing complexity.
Solution Approach 2:
The patent implements local quality by assigning different wire specifications to different spatial locations within the slot. Large cross-sectional area wire is placed in the back region for optimal DC resistance, while small cross-sectional area wire is placed in the front region for optimal AC loss reduction. This localized property assignment achieves performance optimization while maintaining manufacturing feasibility.
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 proposed winding design effectively limits AC losses, enhances motor efficiency, and maintains ease of manufacturing without additional costs by using a weaveless design with balanced conductors.
Implementation Method 1
Small copper wire is typically desirable in order to limit AC resistance due to skin effect and proximity losses
Implementation Method 2
Small copper wire is typically desirable in order to limit AC resistance due to skin effect and proximity losses
Data Source
AI summary
A stator includes a stator core with a plurality of slots and a winding arrangement formed from a plurality of parallel paths. Each parallel path includes a first continuous wire connected in series with a second continuous wire and a third continuous wire, wherein the second and third continuous wire are in parallel. The first continuous wire has a first cross-sectional area and forms a plurality of layers in the back of each slot near the outer diameter. The second and third continuous wire each have a second cross-sectional area and are used to form a plurality of layers in the front of each slot near the inner diameter of the stator. The first cross-sectional area is greater than the second cross-sectional area.