Busbar Cooling Device with Flow Chamber Heat Sink
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Solution Overview
Problem
Conventional cooling methods for busbars in power circuits face inefficiencies due to high thermal resistance and temperature gradients, particularly when using ceramic substrates with low thermal conductivity and thermal pastes or foils, which can create significant thermal barriers and limit heat dissipation.
Innovation Solution
Designing busbars as cooling fins with a flow chamber heat sink that allows forced fluid flow to dissipate thermal energy directly, using copper or aluminum busbars with low thermal resistance and incorporating droplet separators and aerodynamic features to enhance heat transfer and electrical isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermal paste or foil is used between the copper layer and heat sink, then lateral thermo-mechanical expansion is allowed and assembly is easier, but thermal resistance increases and heat dissipation efficiency deteriorates
Solution Approach 1:
The patent removes the thermal paste or foil layer from the heat path between the copper layer and heat sink. By directly bonding the copper layer to the heat sink without intermediate thermal paste/foil, the thermal resistance is significantly reduced while maintaining assembly feasibility through direct thermal and mechanical bonding methods.
Solution Approach 2:
The copper layer serves dual functions: it acts as both the thermal spreading layer and the bonding interface to the heat sink. By eliminating the need for separate thermal paste/foil, the copper layer directly provides both thermal conduction and mechanical bonding functions, reducing the number of components and improving heat dissipation.
2Loss of energy
If the gap between copper layer and heat sink is reduced to minimize thermal barrier, then heat conduction improves, but manufacturing and joining tolerances become more difficult to achieve
Solution Approach 1:
The patent eliminates the gap between the copper layer and heat sink by removing the need for intermediate thermal paste or foil. The copper layer is directly bonded to the heat sink surface, achieving zero or minimal gap width without relying on tight manufacturing tolerances, as the direct bonding process accommodates surface variations.
3Reliability
If conventional heat sink with ceramic substrate is used, then electrical isolation is provided, but thermal conductivity is limited and temperature gradient increases
Solution Approach 1:
Instead of placing the ceramic substrate between the power circuit and heat sink (conventional approach), the patent inverts the approach by using the busbar itself as the cooling fin that directly contacts the coolant. The ceramic substrate is eliminated from the heat path, and electrical isolation is achieved through the coolant channels and housing design rather than through the thermal path materials.
Solution Approach 2:
The patent transitions from relying on through-substrate thermal conduction (limited by ceramic conductivity) to a lateral cooling approach where the busbar extends into the coolant flow. Heat is dissipated through the busbar surfaces exposed to the coolant, utilizing the high thermal conductivity of the busbar material (copper or aluminum) and the convective cooling from the flowing coolant.
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 effectively reduces thermal resistance, ensures safe galvanic isolation, and enhances heat dissipation even in corrosive environments, making it suitable for high-power applications with transient load profiles.
Implementation Method 1
a fluid flow forced within the flow chamber absorbs thermal energy from the surface of the conductor rail (10, 11, 12) designed as a cooling rib projecting into the flow chamber (32, 32A, 32B, 32C) and dissipates the thermal energy
Implementation Method 2
the waste heat from the at least one busbar and/or the power circuit flows predominantly through the thermally and electrically low-impedance designed at least one busbar
Data Source
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AI summary
The invention relates to a device (7, 7A) for cooling at least one bus bar (10, 11, 12) with a base body (20, 20A) and at least one cooling rib, and to a power circuit (1, 1A) comprising such a cooling device (7, 7A). According to the invention, the at least one bus bar (10, 11, 12) is embodied as a cooling rib, at least one cooling body (30, 30A) being embodied as a flow chamber (32, 32A) which partially receives a corresponding bus bar (10, 11, 12), the walls (31, 31A) of said flow chamber forming a flow channel, wherein a fluid flow forced inside the flow chamber (32, 32A) receives and dissipates heat energy from the surface of the bus bar (10, 11, 12) embodied as a cooling rib, protruding into the flow chamber (32, 32A).