Thermally Coupled Busbars for Smaller Battery Pack Bussing
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Solution Overview
Problem
Traditional battery pack bussing configurations require large busbars due to high temperatures, leading to reduced energy density and increased costs, as they are sized based on maximum temperatures and RMS currents across all use cases.
Innovation Solution
The implementation of a thermal interface material (TIM) with a thermal conductivity constant between 1.0 and 7.0 W/mK, which establishes a thermal interface between active and inactive busbars during different modes of the battery pack, allowing heat generated in one busbar to be transferred to another, thereby reducing the size of the busbars and enhancing energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If busbars are sized according to maximum temperature and RMS current across all use cases, then safe and stable operation is ensured, but busbar size increases and energy density decreases
Solution Approach 1:
The patent divides the busbar system into multiple busbars that operate in different modes (charging mode and discharging mode). Each busbar is optimized for its specific operating conditions rather than being oversized for all conditions. The first busbar handles charging currents while the second busbar handles discharging currents, allowing each to be sized appropriately for its intended use.
Solution Approach 2:
The patent implements a dynamic busbar system where the active busbar changes based on operating mode. A control assembly switches between the first busbar during charging and the second busbar during discharging. This dynamic allocation allows the system to adapt busbar usage to actual operational requirements, preventing unnecessary thermal loading on any single busbar.
2Temperature
If larger busbars are used to handle high temperatures, then thermal stability is improved, but energy density of the battery pack decreases
Solution Approach 1:
By segmenting the busbar function into multiple specialized busbars, each busbar experiences reduced thermal loading compared to a single busbar handling all conditions. This allows for more efficient thermal management and reduces the total volume required for thermal stability.
Solution Approach 2:
The patent changes the operational parameters of the busbar system by introducing mode-specific operation. Each busbar is designed for specific current and temperature conditions corresponding to its operating mode, optimizing the thermal parameters for each component rather than designing for worst-case scenarios across all components.
3Reliability
If busbars are oversized for all use cases, then safe operation under maximum conditions is ensured, but manufacturing costs increase
Solution Approach 1:
The patent segments the busbar system into multiple smaller, specialized busbars rather than using fewer oversized busbars. This segmentation allows each busbar to be optimized for specific conditions, reducing material requirements and manufacturing costs while maintaining safety through controlled operational modes.
Solution Approach 2:
The busbar system achieves multi-functionality through the control assembly that switches between different busbars based on operational mode. This universal switching mechanism allows the system to safely handle various charging and discharging conditions using optimized, cost-effective busbar configurations rather than requiring all busbars to handle all conditions.
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 approach reduces the maximum temperature experienced by busbars, allowing for smaller busbar sizes, increased energy density, and lower costs, while maintaining stable and efficient operation of the battery pack.
Implementation Method 1
a thermal interface material (TIM) including a thermal conductivity constant (k) value between 1.0 and 7.0 watts per meter-kelvin (W/mK). The TIM establishes a thermal interface between the first busbar and the second busbar
Data Source
AI summary
A battery pack includes a first busbar, a second busbar, and a thermal interface material (TIM) including a thermal conductivity constant (k) value between 1.0 and 7.0 watts per meter-kelvin (W/mK). The TIM establishes a thermal interface between the first busbar and the second busbar. The battery pack also includes a control assembly configured to regulate a charging mode of the battery pack in which the first busbar is active and receives an electrical current and the second busbar is inactive.