Battery Module Bus Bar Structure for Low-Loss Resistance Welding
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Solution Overview
Problem
The existing bus bars in battery modules experience high electrical resistance, leading to current loss and reduced thermal conductivity, which affects energy efficiency and weldability, and are difficult to weld effectively, increasing manufacturing costs and degrading durability.
Innovation Solution
The bus bar design includes first and second connection extension portions that protrude in different horizontal directions, with narrowed widths and optional bent or curved structures, to increase current flow path length and reduce electrical resistance, enhancing weldability and bonding reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a bus bar material with high electrical resistance is used to increase weldability, then resistance welding becomes easier, but current loss increases and energy efficiency deteriorates
Solution Approach 1:
The bus bar is divided into multiple segments (first bus bar and second bus bar) connected in series along the current flow path. Each segment has optimized electrical resistance characteristics, allowing the overall system to achieve both good weldability at connection points and low current loss in transmission sections.
Solution Approach 2:
Different portions of the bus bar have different electrical resistance characteristics. The connection portions (where welding occurs) have higher resistance to facilitate welding, while the transmission portions have lower resistance to minimize current loss. This local differentiation of properties resolves the contradiction between weldability and energy efficiency.
2Ease of manufacture
If a bus bar material with high electrical resistance is used to improve weldability, then bonding between bus bar and electrode terminal becomes easier, but thermal conductivity decreases and heat dissipation performance deteriorates
Solution Approach 1:
The bus bar system is segmented into multiple portions with different thermal and electrical characteristics. Connection portions are designed with higher resistance for easier welding, while transmission portions maintain lower resistance and higher thermal conductivity for effective heat dissipation.
Solution Approach 2:
Different sections of the bus bar have locally optimized properties: connection zones have higher electrical resistance to facilitate welding, while transmission zones have lower resistance and higher thermal conductivity to ensure efficient heat dissipation and maintain overall thermal performance.
3Loss of energy
If a bus bar material with low electrical resistance is used to reduce current loss, then energy efficiency improves, but weldability decreases and manufacturing time increases
Solution Approach 1:
The bus bar is divided into transmission portions with low resistance (for energy efficiency) and connection portions with higher resistance (for weldability). This segmentation allows each portion to be optimized for its specific function without compromise.
Solution Approach 2:
The bus bar structure implements local quality differentiation where transmission sections have low electrical resistance to minimize current loss, while connection sections have higher resistance to facilitate resistance welding. This resolves the contradiction between energy efficiency and manufacturability.
4Loss of energy
If a bus bar material with low electrical resistance is used to improve energy efficiency, then current loss is reduced, but welding operation time increases and manufacturing costs increase
Solution Approach 1:
The bus bar is segmented into low-resistance transmission portions and higher-resistance connection portions. This allows welding operations to be performed quickly on the higher-resistance connection sections while the low-resistance transmission sections maintain energy efficiency, reducing overall manufacturing time and costs.
Solution Approach 2:
Different sections of the bus bar have locally optimized electrical resistance: connection zones have higher resistance to enable faster, more efficient welding operations, while transmission zones have lower resistance to minimize current loss. This differentiation reduces both welding time and manufacturing costs while maintaining energy efficiency.
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 improves resistance welding efficiency, reduces current loss, and increases manufacturing efficiency while maintaining durability by optimizing current flow and positioning, even with lower electrical resistance materials.
Implementation Method 1
bonding the electrode terminal to the end portions by resistance welding
Data Source
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AI summary
Provided are a battery module including a bus bar, whereby weldability may be increased by reducing current loss when welding the bus bar and an electrode terminal of a battery cell, and a battery pack including the battery module. The battery module includes: a plurality of cylindrical battery cells; a module housing; and a bus bar configured to contact the electrode terminals of the plurality of cylindrical battery cells to electrically connect between the plurality of cylindrical battery cells, wherein the bus bar includes: a main body portion that is positioned over or below the plurality of cylindrical battery cells and has a plate shape that is flat in a horizontal direction, wherein at least one coupling opening perforated vertically is formed in the plate shape; and a first connection extension portion and a second connection extension portion that protrude and extend from an internal boundary of the coupling opening in different horizontal directions from each other and have end portions that are electrically connected and fixed to an electrode terminal of one of the plurality of cylindrical battery cells.