Power Converter Capacitor Busbar Cooling for Longer Service Life
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Solution Overview
Problem
Existing power converters face challenges in effectively cooling capacitors, leading to increased temperatures and reduced service life, especially with higher voltages, currents, and switching frequencies, which can result in higher power losses and increased costs.
Innovation Solution
A capacitor unit design featuring a first and second busbar with a capacitor element between them, a cooling device thermally coupled via a thermal conductor, and a housing that encases the components, along with spring elements to compensate for tolerances, ensuring effective heat dissipation and electrical insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitors are cooled more effectively, then service life is extended and reliability is improved, but device complexity increases due to additional cooling components
Solution Approach 1:
The cooling device is merged with the busbar structure by directly coupling the cooling body to the first busbar, which serves dual purposes as both an electrical conductor and a heat dissipation component. This integration reduces the number of separate cooling components needed while maintaining effective cooling of the capacitor element.
Solution Approach 2:
The first busbar is designed to serve multiple functions: electrical connection to the capacitor element and thermal conduction to the cooling device. This multi-functionality reduces the need for additional dedicated cooling components, thereby extending capacitor service life without proportionally increasing device complexity.
2Volume of moving object
If capacitor size is reduced, then overall power converter size is reduced, but heat dissipation capability deteriorates
Solution Approach 1:
The cooling device extends in the vertical dimension with cooling fins that protrude from the cooling body, increasing the heat dissipation surface area without significantly increasing the horizontal footprint of the capacitor. This allows smaller capacitors to maintain effective heat dissipation capability.
Solution Approach 2:
The cooling body is segmented into multiple cooling fins that are arranged to maximize surface area for heat dissipation. This segmentation allows efficient heat removal from compact capacitors by distributing the thermal load across multiple fin surfaces.
3Adaptability or versatility
If spring elements are added to compensate for tolerances, then adaptability to different capacitor dimensions is improved, but device complexity increases
Solution Approach 1:
The spring element provides a dynamic, elastic connection between the second busbar and the capacitor element, allowing the connection to adapt to dimensional variations in the capacitor winding. This dynamic compensation mechanism enables the same busbar design to work with capacitors of slightly different dimensions without requiring custom adjustments.
Solution Approach 2:
The spring element changes its physical parameters (compression/extension) to accommodate variations in capacitor winding dimensions. This parameter change allows the second busbar to maintain reliable electrical contact with capacitor elements that have slight dimensional tolerances, improving adaptability without complex adjustment mechanisms.
4Loss of energy
If thermal conductor surface area is increased, then heat transfer efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The thermal conductor is implemented as a thin, flexible adhesive film that can conform to the surfaces of both the busbar and cooling body. This film geometry provides large surface area for heat transfer while being tolerant of manufacturing variations, as the flexible nature of the thin film allows it to accommodate minor surface irregularities without requiring extremely tight manufacturing tolerances.
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
The design extends the service life of capacitors, reduces overall size, and lowers costs by improving cooling efficiency and accommodating capacitors with varying dimensions, while maintaining reliable electrical contact.
Implementation Method 1
the cooling device is thermally coupled over with a surface area contact to the first busbar... The thermal conductor is in between the first busbar and the cooling body and can be thermally coupled thereto. The thermal conductor can be designed to transfer heat from the first busbar to the cooling body.
Implementation Method 2
a cooling body for discharging heat... the cooling device is designed to remove heat from the first busbar
Implementation Method 3
The second busbar, on the second side of the capacitor element, can be have at least one spring element, which can be pretensioned against the capacitor element. In particular, the spring element can press the capacitor toward the first busbar.
Data Source
AI summary
A capacitor unit for a power converter, wherein the capacitor unit has a first busbar and a second busbar, and at least one capacitor element placed in between the first busbar and the second busbar, wherein the capacitor element is electrically connected to the first busbar at a first side, and wherein the capacitor element is electrically connected to the second busbar at a second side, lying opposite the first side, and a cooling device, wherein the cooling device is thermally coupled to the first busbar with a surface area contact, wherein the cooling device is designed to remove heat from the first busbar.