Integrated DC Busbar and Capacitor Thermal Management
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Solution Overview
Problem
Existing DC link capacitor systems in electric vehicles face overheating and unwanted DC voltage ripple due to heating of busbars and high stray inductance values, which limit the lifespan and efficiency of the capacitors.
Innovation Solution
The integration of DC busbars into the DC-link capacitor with a heat sink, where the positive and negative busbars are embedded within the capacitor winding, separated by a dielectric layer, and connected underneath the capacitor, allowing heat dissipation and reduced inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If busbars are wrapped around or traverse over the capacitor to connect terminals, then electrical connection is achieved, but busbar heating causes capacitor overheating and reduced lifespan
Solution Approach 1:
The busbars are integrated directly into the capacitor structure, with positive and negative busbars formed as part of the capacitor winding itself. This merging eliminates separate busbar connections and their associated heating problems, while maintaining electrical connection functionality through the integrated electrode-busbar structure.
Solution Approach 2:
A dielectric layer is introduced as an intermediary between the positive and negative busbars that are in close proximity. This dielectric barrier enables the busbars to be positioned adjacently for compact design and improved cooling, while preventing electrical breakdown and maintaining insulation between the conductive elements.
2Reliability
If busbars extend from Power Inverter Module DC input to DC link capacitor connection terminals, then electrical connection is established, but longer busbar length increases stray inductance and causes DC voltage ripple
Solution Approach 1:
The busbars are merged with the capacitor electrodes, eliminating the need for separate connection conductors. The positive busbar becomes part of the positive electrode and the negative busbar becomes part of the negative electrode, drastically reducing the current path length and associated stray inductance.
Solution Approach 2:
The busbars are repositioned from external connections traversing the capacitor exterior to internal integrations within the capacitor winding structure. This dimensional repositioning reduces the current path from external loops to internal compact pathways, minimizing inductance.
3Area of stationary object
If busbars are positioned immediately adjacent to the capacitor for compact design, then space is optimized, but busbar heating cannot be effectively dissipated
Solution Approach 1:
The busbars are combined with the capacitor electrodes and positioned within the capacitor's internal structure. This integration allows the capacitor's existing thermal management infrastructure to serve the busbars, dissipating heat from both components simultaneously through the same thermal pathways.
Solution Approach 2:
The capacitor structure itself serves as the thermal management system for the busbars. The capacitor's electrodes, winding structure, and cooling pathways are utilized to dissipate heat from the integrated busbars, eliminating the need for separate cooling infrastructure.
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 reduces overheating and stray inductance, extends the lifespan of the capacitors, and maintains current carrying capability while lowering costs and improving thermal management.
Implementation Method 1
the busbars and the DC link connection terminals are connected underneath the capacitor and are positioned on top of a heat sink. In operation, any heating of the busbars is simply transferred down into the heat sink below the capacitor.
Implementation Method 2
the DC positive busbar is integrated into the positive electrode of the capacitor winding, and the DC negative busbar is integrated into the negative electrode of the capacitor winding. Preferably, these two integrated busbars are separated by a dielectric layer.
Data Source
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AI summary
A system for preventing overheating of a DC link capacitor in an electric vehicle, including: a DC link capacitor having a positive electrode and a negative electrode; a pair of busbars, with the positive busbar connected to the positive electrode of the DC link capacitor, and the negative busbar connected to the negative electrode of the DC link capacitor; a dielectric layer between the positive and negative busbars; a pair of DC output connectors connected to the busbars; and a heat sink positioned under the busbars and in contact with the busbars.