Stator Bus Bar Cross Section and Pin Placement
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Solution Overview
Problem
Rotating electric machines in vehicles face issues with stress from temperature differences in bus bars, generation of eddy currents through attachment pins, and insulation defects due to abnormal heat generation in stator windings.
Innovation Solution
The stator design incorporates phase windings with parallel connections, bus bars with varying cross-sectional areas to reduce current density differences, and attachment pins positioned at angles that eliminate changes in magnetic flux, along with heat releasing members to manage thermal issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the bus bar has a uniform cross-sectional area, then the manufacturing is simple, but the current density difference causes temperature difference stress
Solution Approach 1:
The bus bar cross-sectional area is varied locally along its length, with the first end portion having a different area than the second end portion. This local variation optimizes current density distribution to reduce temperature difference stress while maintaining manufacturing feasibility.
2Reliability
If attachment pins are used to connect the bus bar to the stator core, then the electrical connection is established, but eddy currents are generated through the steel plates
Solution Approach 1:
The attachment pins are strategically positioned to extract or avoid creating closed loops that would generate eddy currents. The pins connect the bus bar to the stator core while minimizing their involvement in current paths that could induce eddy currents in the laminated steel plates.
Solution Approach 2:
The attachment pins serve as intermediaries for electrical connection between the bus bar and stator core, but their design and positioning ensure they do not create harmful eddy current paths through the laminated structure.
3Productivity
If the stator winding uses distributed winding with phase windings of differing phases near each other, then the winding distribution is optimized, but insulation defects may occur due to abnormal heat generation
Solution Approach 1:
Heat releasing members are selectively positioned at specific locations where phase windings of differing phases are adjacent to each other. These members locally address heat management needs without affecting the overall distributed winding configuration.
Solution Approach 2:
Heat releasing members act as intermediaries between the phase windings and the surrounding environment, facilitating heat dissipation from critical areas where insulation defects could occur due to abnormal heat generation.
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
This design reduces stress from temperature differences, minimizes eddy current generation, and prevents insulation defects by ensuring consistent current flow and effective heat management.
Implementation Method 1
the difference in density of the current flowing through the bus bar... stress attributed to temperature difference
Implementation Method 2
eddy currents that pass through the attachment pins are generated... angle formed by two slots... angle formed by two attachment holes
Data Source
AI summary
In a stator of a rotating electric machine, an annular stator core has slots. A stator winding includes phase windings of three phases of differing electrical phases that are housed in the slots and wound around the stator core. Three phase bus bars electrically connect the respective phase windings to an external apparatus. Each of the phase windings are configured by multiple parallel windings. The phase bus bars are integrated with a fixing member to form a bus bar module. Each of the phase bus bars include branch portions and a trunk portion. The branch portions are electrically connected to the respective phase windings. The trunk portion electrically connects together the branch portions, and is configured that a cross-sectional area of an end portion closest to the phase winding is smaller than a cross-sectional area of an end portion closest to the external apparatus.