Concentric Stator Coil Segmentation for Rotating Electrical Machines
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Solution Overview
Problem
In rotating electrical machines with lap winding, the rigidity and operability of coils are compromised due to their large number of turns, leading to difficulties in inserting them into slots and resulting in uneven coil ends that do not contribute to machine performance.
Innovation Solution
The coils are divided into two groups with shorter circumferential lengths for the inner coil group, allowing concentric arrangement with the outer group, reducing coil end heights and improving flexibility and operability by reducing the number of turns and copper wire usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If coils are divided into two groups and inserted radially double, then the number of turns per coil is reduced improving flexibility and operability, but differences in coil end heights occur between outer peripheral side and inner peripheral side
Solution Approach 1:
The patent segments the coil structure by dividing the winding into an outer coil group and an inner coil group with different circumferential lengths. Each group is inserted into corresponding slots independently, allowing the outer coil group to have more turns than the inner coil group. This segmentation resolves the contradiction by enabling flexible insertion of each group while accommodating the natural height difference through separate positioning.
Solution Approach 2:
The patent applies local quality by assigning different circumferential lengths to different radial positions. The outer coil group has a longer circumferential length suitable for the outer peripheral slots, while the inner coil group has a shorter circumferential length for the inner peripheral slots. This localized differentiation allows each coil group to be optimally fitted to its specific position, resolving the height uniformity issue while maintaining operational flexibility.
2Reliability
If a coil is made by winding copper wire at a large number of times, then the coil has sufficient electrical properties, but the coil lacks flexibility and has low operability in inserting it into a slot
Solution Approach 1:
The patent segments the total winding into multiple coil groups (outer and inner groups) that can be inserted separately. Each group contains a portion of the total turns, so no single coil needs to accommodate all turns. This segmentation maintains the required electrical properties through the combined turns of multiple groups while significantly improving insertion flexibility, as each smaller group is easier to manipulate and insert into slots.
3Ease of operation
If coils per pole per phase are divided into two groups, then flexibility and operability improve, but parts located at the coil ends do not contribute to performance and space is wasted
Solution Approach 1:
The patent applies local quality by giving different circumferential lengths to the outer and inner coil groups, matching each group's length to its specific radial position and functional requirements. The outer coil group has longer circumferential length to span the necessary slots at the outer periphery, while the inner coil group has shorter length appropriate for inner peripheral slots. This localized optimization ensures that copper wire is used efficiently in each position without excessive waste, while still providing the flexibility benefits of divided groups.
Data Source
AI summary
A rotating electrical machine includes a stator having a stator core, coil groups, and a rotor. The coil groups include a first coil group located at an outer circumference side of the stator core and a second coil group located at an inner circumference side of the stator core. The first and second coil groups are formed into an annular shape by inserting unit coils into stator core slots so that the coils adjacent in a circumferential direction overlap alternately in a radial direction and so that an inside and an outside of the overlap alternate with each other. The first coil group is disposed to surround an outside of the second coil group. The first and second coil groups are disposed in a concentric manner. The unit coils constituting the second coil group have shorter circumferential lengths than the unit coils constituting the first coil group.