Segmented Busbar Insulation for Power Converter Thermal Management
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Solution Overview
Problem
Conventional busbar devices for power converters in vehicles face inadequate heat dissipation due to high heat transfer resistance from the insulating body, leading to increased conductor cross-sections, weight, and cost, which are undesirable for space-saving and weight-saving designs in electromobility.
Innovation Solution
The solution involves forming openings in the insulating body to expose busbar sections for direct heat transfer to a low-resistance heat transfer medium, such as a gap filler, which is electrically insulating, allowing for efficient heat dissipation without additional components, and incorporating projections and spacers for enhanced electrical safety and creepage distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulating body completely covers the busbars, then electrical insulation is improved, but heat dissipation deteriorates due to high heat transfer resistance
Solution Approach 1:
The insulating body is segmented to create openings in the temperature control area, allowing parts of the busbar bases to remain exposed. This segmentation enables simultaneous electrical insulation where needed and thermal contact where required, resolving the contradiction between complete coverage for insulation and partial exposure for heat dissipation.
Solution Approach 2:
Different regions of the busbar device are assigned different functions: the insulating body provides electrical insulation in non-temperature control areas, while openings in the temperature control area allow direct thermal contact between busbar bases and the heat transfer medium. This local differentiation resolves the contradiction by applying insulation only where electrically necessary while maintaining thermal pathways.
2Reliability
If larger conductor cross-sections are used to compensate for poor heat dissipation, then current-carrying capacity is maintained, but weight and space increase
Solution Approach 1:
The heat dissipation function is extracted from the insulating body by creating openings that allow direct contact between the busbar bases and the heat transfer medium. This extraction eliminates the thermal resistance barrier, enabling effective cooling without requiring oversized conductors, thus reducing weight while maintaining current-carrying capacity.
Solution Approach 2:
A heat transfer medium (gap filler) is introduced as an intermediary substance between the exposed busbar bases and the cooling system. This mediator provides efficient thermal transfer while maintaining electrical insulation, allowing compact busbar design with adequate current-carrying capacity without excessive weight.
3Temperature
If openings are formed in the insulating body, then heat dissipation is improved, but electrical insulation may be compromised
Solution Approach 1:
A heat transfer medium with electrical insulating properties (gap filler) is introduced as an intermediary between the exposed busbar bases and the cooling structure. This mediator enables thermal transfer while maintaining electrical insulation, resolving the contradiction between heat dissipation and electrical safety.
Solution Approach 2:
The insulating body is configured to provide electrical insulation in critical areas while leaving non-critical areas exposed for thermal contact. The heat transfer medium fills the openings to provide both thermal pathways and electrical insulation, creating local functional differentiation that satisfies both requirements simultaneously.
4Temperature
If powder-coated busbars are used for direct attachment to metal housing, then heat dissipation is improved, but production cost increases and connecting elements cannot be formed
Solution Approach 1:
The insulating body is formed as a composite structure combining insulating material with integrated cooling features (openings and protrusions). This composite design provides both electrical insulation and thermal management functionality in a single manufacturable component, avoiding the need for expensive powder-coated busbars while enabling direct integration of connecting elements during injection molding.
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 enables smaller conductor cross-sections, reduced weight, and lower production costs while improving cooling efficiency and electrical safety, allowing for more compact and cost-effective busbar devices with enhanced heat dissipation capabilities.
Implementation Method 1
heat transfer via the insulating body, which has a relatively high heat transfer resistance, is avoided and the significantly lower heat transfer resistance of the heat transfer medium is used instead
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Arrangement (5) with a busbar assembly (7) and a converter housing (6), wherein the busbar assembly comprises a stack of at least two busbars (7a-7c) and an electrically insulating insulating body (9) enclosing the busbars (7a-7c) in two insulating regions (10a-10d) of the busbar assembly (7), wherein each busbar (7a-7c) has two opposing base surfaces (14a, 14b) extending in the direction of current flow and side surfaces (13a, 13b) connecting the base surfaces (14a, 14b) and extending in the direction of current flow, wherein the busbar assembly (7) has a temperature control region (11a-11c) formed between the insulating regions (10a-10d) in which the insulating body (9) has an opening (12) that allows one of the side surfaces (13a) and a part of at least one of the base surfaces (14a, 13b) to pass through. 14b) exposes a respective busbar (7a-7c),wherein the busbars (7a-7c) in the temperature control area (11a-11c) are thermally connected to the converter housing (6) by a heat transfer medium (19).