Clad Metal Bus Bar for Film Capacitor Weight Reduction
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Solution Overview
Problem
Conventional copper bus bars used in film capacitors for hybrid electric vehicles are too heavy due to their high specific gravity, which complicates handling and can lead to reduced reliability and lifetime due to heat generation under high voltage or current conditions, necessitating a lighter yet robust alternative.
Innovation Solution
A clad metal bus bar is developed, comprising an aluminum layer sandwiched between two copper layers, with specific thickness ratios and percentage reductions, enhancing bond strength, elongation percentage, and electrical conductivity, while reducing weight and maintaining mechanical strength and formability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pure copper bus bars are used, then electrical conductivity is excellent, but weight becomes too heavy
Solution Approach 1:
The patent applies composite materials by creating a clad metal structure with copper layers on the surface and aluminum in the core. This composite structure combines the high electrical conductivity of copper with the low weight of aluminum, achieving a bus bar that is 40% lighter than pure copper while maintaining excellent electrical conductivity through the copper surface layers.
2Weight of moving object
If copper layers are made thinner to reduce weight, then weight decreases, but bond strength deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness ratio of copper layers to aluminum core within specific ranges (copper layers: 10-25% of total thickness, aluminum core: 50-70% of total thickness). This parameter optimization ensures adequate bond strength while achieving significant weight reduction, with the clad metal layer having a percentage reduction in thickness of less than 10% and elongation of 25% or more.
3Weight of moving object
If aluminum layer thickness is increased to reduce weight, then weight decreases, but electrical resistance increases
Solution Approach 1:
The patent applies local quality by placing copper layers specifically at the surface regions where electrical conduction occurs, while using lightweight aluminum for the internal core structure. This spatial distribution of material properties ensures that the copper surface layers provide excellent electrical conductivity where needed, while the aluminum core provides weight reduction, achieving electrical conductivity of 60 IACS % or more.
4Weight of moving object
If clad metal layer is reduced in thickness for weight reduction, then weight decreases, but formability deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the percentage reduction in thickness of the clad metal layer to be less than 10% and ensuring elongation is 25% or more. These parameter constraints maintain the formability and manufacturability of the bus bar while achieving significant weight reduction through the optimized clad metal structure.
Data Source
AI summary
A clad metal bus bar for a film capacitor may include a clad metal layer including: an aluminum layer; a first copper layer stacked on one surface of the aluminum layer; and a second copper layer stacked on the other surface of the aluminum layer.