Overmolded Busbar Cooling Paths for Battery Pack Joule Heat
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Solution Overview
Problem
High-voltage battery packs experience suboptimal cooling and potential degradation due to Joule heating at cell tab-to-busbar interfaces, leading to inefficiencies and structural issues.
Innovation Solution
The integration of dielectric material overmolding on busbar ends to form a high-voltage barrier and create multiple parallel cooling paths into a heat sink, facilitated by a thermally conductive interconnect board and thermal interface material, enhances heat transfer and cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional cooling approaches are used with high-voltage battery packs, then the battery pack structure is simple, but the cooling efficiency is suboptimal and Joule heating effects are not effectively mitigated
Solution Approach 1:
The patent divides the cooling function into multiple parallel cooling paths, with each busbar having its own dedicated cooling path through the heat sink. This segmentation allows heat from each cell tab-to-busbar interface to be removed independently, effectively mitigating Joule heating effects at multiple locations simultaneously.
Solution Approach 2:
The dielectric material is overmolded directly onto the busbar ends, creating a nested structure where the dielectric material contains the cooling channels that in turn contain the coolant flow. This nested arrangement integrates multiple functions (electrical insulation, thermal management, structural support) into a compact configuration.
2Temperature
If dielectric material is overmolded onto busbar ends to create cooling paths, then cooling efficiency is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into the dielectric material overmolding: electrical insulation between the busbar and heat sink, structural support for the busbar, and formation of cooling channels through which coolant flows. This consolidation improves cooling efficiency while minimizing the increase in device complexity by using a single integrated component.
Solution Approach 2:
The dielectric material overmolding serves multiple purposes simultaneously: it provides electrical insulation, structural support, and thermal management through integrated cooling channels. This multi-functionality allows the same component to address multiple requirements, reducing the need for separate parts and assembly steps.
3Reliability
If multiple parallel cooling paths are created through overmolding, then heat transfer efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The cooling channels are formed within the dielectric material during the overmolding process itself, before the busbar is installed or coolant is introduced. This preliminary formation of cooling paths eliminates the need for subsequent machining or assembly steps, improving heat transfer efficiency while maintaining ease of manufacture.
Solution Approach 2:
The patent replaces traditional mechanical cooling systems (separate coolant channels, mounting brackets, fasteners) with an integrated overmolded structure. The dielectric material itself forms the cooling channels, substituting complex mechanical assemblies with a single molded component that achieves the same thermal management function.
4Reliability
If dielectric material is used to form high-voltage barrier, then electrical safety is improved, but thermal conduction path is interrupted
Solution Approach 1:
The dielectric material is applied locally only where electrical insulation is required (at the busbar ends near the heat sink interface), while the busbar remains exposed along its length for electrical connections. This localized application maintains high-voltage barrier integrity at critical interfaces without interrupting thermal conduction paths where heat needs to be transferred.
Solution Approach 2:
The dielectric material acts as an intermediary that provides electrical insulation while still allowing thermal energy to pass through via conduction. The material's thermal conductivity is sufficient to maintain effective heat transfer, while its dielectric properties ensure electrical safety, mediating between the conflicting requirements of electrical isolation and thermal conduction.
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 solution effectively mitigates Joule heating effects, improves temperature regulation, and enhances the structural integrity of battery packs by providing direct and efficient cooling paths, reducing the risk of degradation and maintaining power efficiency.
Implementation Method 1
Heat transfer to the heat sink typically occurs over a highly-resistive path from the various cell tab-to-busbar interfaces through intervening material of the battery pack... the dielectric material covering the distal ends of the busbars serves as part of a high-voltage barrier between the bus bars and the heat sink, while at the same time facilitating heat transfer into the heat sink
Implementation Method 2
The overmolded ends of the busbars are bonded to the elongated bracket within the bracket pocket using a thermal interface material (TIM)
Implementation Method 3
High-voltage battery packs tend to experience substantial levels of Joule heating during sustained operation. Such heating is prevalent at or along welded or bonded joints connecting the individual cell tabs to the busbars of a high-voltage bus
Implementation Method 4
Heat transfer to the heat sink typically occurs over a highly-resistive path from the various cell tab-to-busbar interfaces through intervening material of the battery pack
Data Source
AI summary
A battery pack includes battery cells and an interconnect board assembly (ICBA) having a dielectric ICB and parallel busbars. A cell tab protrudes from an edge of the cells and joined to the busbars. A dielectric ICB is connected to the busbars at one distal end of the busbars. The dielectric material of the ICB is overmolded onto another distal end such that the ICB wraps around the busbars to form overmolded ends. The overmolded ends are received within a pocket of a bracket to form direct parallel cooling paths to a heat sink. A method of manufacturing the battery pack includes arranging the busbars in parallel, overmolding dielectric material onto ends of the busbars to form overmolded ends, and attaching the busbars to a plastic ICB formed from the dielectric material. The ICBA is then attached to the bracket and cells.