Radial Bus Bar Layout for Compact Electric Machine Stators
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Solution Overview
Problem
Existing electric machine stators face challenges in packaging due to the tall bus bars required for connecting leads, which worsens with increased number of slots per pole per phase, parallel wires, or phases, especially when series connections are needed.
Innovation Solution
A stator design with a cylindrical core and a bus bar assembly that includes inner and outer bus bars positioned radially and axially to reduce the overall length of the stator, allowing for efficient connection of leads while maintaining stability and cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional bus bar connections are used to connect leads in series and create neutral points, then the electrical connections are completed, but the bus bars become tall in the axial direction extending beyond the winding end turns
Solution Approach 1:
The patent transitions the bus bar connection arrangement from a traditional axial configuration to a radial configuration. The bus bars are positioned radially outward from the end turns of the windings, utilizing the radial dimension instead of extending axially. This dimensional change allows electrical connections to be made without increasing the axial length of the stator assembly, thereby resolving the contradiction between connection reliability and axial length.
Solution Approach 2:
The bus bars are nested within the radial space between the end turns and the outer cylindrical surface of the stator core. This nesting arrangement allows the bus bars to be accommodated within the existing radial envelope of the stator without requiring additional axial space, effectively resolving the space constraint issue while maintaining electrical connection functionality.
2Power
If the number of slots per pole per phase, parallel wires per phase, or phases is increased to meet performance requirements, then the electrical performance is improved, but the bus bar assembly becomes more complex and requires more connections
Solution Approach 1:
By arranging bus bars radially rather than axially, the patent creates a more compact connection architecture that scales better with increased complexity. The radial arrangement allows multiple bus bars to be positioned at different radial locations without proportionally increasing axial height, making it easier to manage complex connection requirements for high-power machines with more phases and parallel wires.
Solution Approach 2:
The patent changes the geometric parameters of the bus bar assembly by positioning bus bars at specific radial distances from the end turns. This parameter change optimizes the spatial distribution of connections, allowing for more efficient routing and reduced complexity even as the number of connections increases with higher power requirements.
3Length of moving object
If the axial length of the stator is reduced to facilitate packaging in limited spaces, then the packaging efficiency is improved, but the space for bus bar connections is reduced
Solution Approach 1:
The patent compensates for reduced axial length by utilizing the radial dimension for bus bar connections. The bus bars are positioned radially outward from the end turns, within the space between the end turns and the outer cylindrical surface. This radial utilization allows the axial length to be reduced for better packaging while maintaining adequate space for connections through the radial direction.
Data Source
AI summary
A stator for an electric machine comprises a cylindrical core defining an inner cylindrical surface and an outer cylindrical surface with a plurality of slots formed between the inner cylindrical surface and the outer cylindrical surface. Windings are positioned on the cylindrical core. The leads of the windings include a plurality of inner leads associated with conductors in an inner layer of the slots and a plurality of outer leads associated with conductors in an outer layer of the slots. A bus bar assembly includes a plurality of inner bus bars and a plurality of outer bus bars, the plurality of inner bus bars connected to the plurality of inner leads, and the plurality of outer bus bars connected to the plurality of outer leads. The plurality of outer bus bars are positioned radially outward from the end turns of the windings and radially inward from the outer cylindrical surface.