Rotor Shaft Housing Layout for High-Current Cable Routing
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Solution Overview
Problem
The power output of rotating electrical machines is limited by the size of the cable section, which restricts the current flow and requires significant clearance volume due to large cable radii, leading to inefficiencies in current circulation and mechanical rigidity.
Innovation Solution
A shaft design with axially extending housings that accommodate insulated electrical conductors, featuring a combination of rectangular and trapezoidal grooves to securely hold the conductors, ensuring sufficient rigidity and minimizing deflection, while allowing for increased current flow and reduced curvature radius.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large section electrical cables are used to increase current flow capacity, then the electrical power developed by the machine increases, but the bend radius requires significant clearance volume and the shaft rigidity decreases
Solution Approach 1:
The electrical conductor is divided into multiple smaller conductors (e.g., three conductors per phase) that are arranged in parallel within the housing. This segmentation allows the current to be distributed across multiple smaller paths, reducing the bend radius requirement for each individual conductor while maintaining the total current flow capacity. The conductors are positioned in a compact configuration within the shaft housing, eliminating the need for large clearance volumes.
2Power
If large section electrical cables are used to increase current flow capacity, then the electrical power developed by the machine increases, but the shaft rigidity decreases due to reduced material thickness
Solution Approach 1:
The conductor arrangement is segmented into multiple smaller conductors positioned in specific locations within the housing, allowing the shaft wall thickness to be optimized for rigidity while accommodating the conductor bundle. The conductors are positioned away from the shaft outer diameter, preserving the structural integrity and bending stiffness of the shaft.
Solution Approach 2:
The conductors are arranged in a three-dimensional configuration within the housing, utilizing the axial and radial dimensions efficiently. This spatial arrangement allows the conductors to be positioned in a compact volume that does not compromise the shaft's external dimensions and rigidity characteristics.
3Ease of operation
If the shaft is drilled in the center to allow cable passage, then the current flow is simplified, but the shaft rigidity is reduced and the bending and torsion modes fall within the operating speed range
Solution Approach 1:
The conductor passage function is extracted from the shaft center and relocated to a housing structure on the shaft surface. This extraction preserves the shaft's central structural integrity and rigidity while providing a dedicated pathway for the electrical conductors through the housing, which is positioned on the shaft periphery.
Solution Approach 2:
A housing structure serves as an intermediary element between the shaft and the electrical conductors. The housing is mounted on the shaft surface and provides the conductor passage function, while the shaft itself maintains its full structural integrity without central drilling. The housing acts as a mediator that separates the structural function (shaft) from the electrical function (conductor passage).
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The shaft for a rotating electrical machine includes at least one housing (8a, 8b, 8c) extending along an axial direction (A) and opening outwards along a radial direction, one side of the housing opening outwards along an axial direction, the housing being suitable for receiving at least one insulated electrical conductor (6) and a shim (9a, 9b, 9c).