Nested Three-Phase Bus Bar for Compact Motor Winding
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Solution Overview
Problem
In high-efficiency electric motors, particularly in hybrid and electric vehicles, there is a challenge in compactly and efficiently distributing electric current to motor windings due to packaging constraints, which affects the motor's power output and efficiency.
Innovation Solution
A nested three-phase bus bar configuration is introduced, featuring planar branches and legs with specific slot sizes and orientations to receive phase lead and neutral ends of windings, allowing for compact arrangement within an enclosure while maintaining electrical and thermal insulation, and accommodating thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional bus bar arrangements are used, then electrical current distribution is achieved, but the motor volume and weight increase due to non-compact packaging
Solution Approach 1:
The bus bar unit employs a nested configuration where multiple bus bars are arranged in concentric layers within a single enclosure. The first bus bar is positioned in an outer layer, the second bus bar in an intermediate layer, and the third bus bar in an inner layer, with each bus bar nested within the spatial envelope of the previous one. This nesting arrangement dramatically reduces the overall volume occupied by the bus bar assembly while maintaining all necessary electrical connection pathways.
Solution Approach 2:
The invention transitions from a planar or linear bus bar arrangement to a three-dimensional nested structure. By utilizing radial and axial positioning in cylindrical coordinates, the bus bars are distributed across multiple spatial dimensions (outer/intermediate/inner layers) rather than occupying a single plane or line, thereby achieving compact packaging without excessive complexity.
2Temperature
If bus bar spacing is increased for thermal expansion, then thermal accommodation is improved, but the compactness and power density decrease
Solution Approach 1:
The bus bar unit incorporates dynamic clearance design where the spacing between nested bus bars is intentionally optimized to accommodate thermal expansion during operation. The intermediate and inner layers are positioned with sufficient radial clearance from the outer layer to allow for temperature-induced dimensional changes without mechanical contact or deformation, while still maintaining compact overall dimensions.
Solution Approach 2:
The design explicitly accounts for thermal expansion by providing adequate spacing between the nested bus bars in the radial direction. As the bus bars heat up during motor operation, they can expand without contacting adjacent bus bars, preventing short circuits and mechanical stress, while the compact nested arrangement minimizes the volume required for this thermal clearance.
Data Source
AI summary
Certain aspects relate to a bus bar unit for providing three phases of electric current to the windings of the stator of an electric machine while structured to have a compact footprint for fitting within the enclosure of the electric machine. Each winding can have a phase lead end and a neutral end extending above one face of the stator. The bus bar unit can include three phase lead bus bars and a neutral bus bar each having a planar branch with legs extending from the planar branch, each leg having a slot at an end thereof for electrically coupling with either the phase lead or the neutral end of one or more of the windings. The planar branches can be stacked such that they overlap from a top-down perspective but are spaced apart from a side perspective.