Inverter DC-Link Capacitor Packaging With Thermal Isolation Layer
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Solution Overview
Problem
Traditional dc-link capacitors in inverter power modules suffer from poor thermal conductivity, leading to significant temperature increases that can reduce their lifespan and require oversized designs to handle heat, increasing the size, cost, and weight of inverter systems.
Innovation Solution
A thermally enhanced capacitor package with a bus bar and isolation layer configured to dissipate heat from the bus bar to the case, providing improved thermal conductivity and reducing capacitor temperatures, allowing for smaller, more economical capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional capacitor package is used with poor thermal conductivity, then capacitor can be simpler and cheaper, but temperature increases significantly reducing lifespan and requiring oversized design
Solution Approach 1:
A thermally conductive adhesive is introduced as an intermediary material between the capacitor elements and the package substrate. This adhesive layer has superior thermal conductivity compared to traditional resin materials, enabling efficient heat transfer from the capacitor elements to the substrate while maintaining electrical insulation. The intermediary material resolves the contradiction by providing a thermal pathway without compromising electrical performance.
Solution Approach 2:
The package employs composite material construction combining thermally conductive adhesive with the package substrate and capacitor elements. This composite structure integrates materials with different properties: the adhesive provides thermal conductivity and electrical insulation, while the substrate provides mechanical support and additional thermal pathways. The composite approach enables simultaneous improvement of thermal management and electrical performance.
2Temperature
If capacitor size is increased to withstand thermal challenges, then temperature tolerance is improved, but size, cost and weight of inverter system increase
Solution Approach 1:
The thermally conductive adhesive acts as a heat transfer intermediary that enables smaller capacitors to dissipate heat effectively. By improving the thermal pathway from capacitor elements to the package substrate, the adhesive allows reduced capacitor sizing while maintaining temperature tolerance, thereby reducing inverter system weight without compromising thermal performance.
Solution Approach 2:
The thermal conductivity parameter of the adhesive material is optimized to enable effective heat dissipation in compact designs. By changing the thermal parameters of the packaging materials, the system achieves better temperature management in smaller form factors, allowing reduced capacitor size while maintaining temperature tolerance and reducing overall system weight.
3Temperature
If thermally enhanced isolation layer is added to dissipate heat, then thermal conductivity is improved, but device complexity increases
Solution Approach 1:
The thermal management function is merged with the existing package substrate structure. The thermally conductive adhesive is applied directly to the capacitor elements and bonded to the package substrate, combining the electrical insulation and thermal conduction functions into a single integrated layer. This merging approach improves heat dissipation capability while minimizing additional structural complexity.
Solution Approach 2:
The package substrate serves multiple functions: mechanical support, electrical insulation, and thermal conduction pathway. By making the substrate multi-functional, the design avoids adding separate thermal management components, thereby improving heat dissipation capability while keeping device complexity low. The adhesive layer also provides electrical insulation while enabling thermal transfer.
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 enhanced package effectively dissipates heat, lowering capacitor temperatures and extending lifespan, enabling the use of smaller capacitors that maintain electrical performance while reducing system size and cost.
Implementation Method 1
an isolation layer disposed between and adjacent the bus bar and the case... effectively dissipates heat from the bus bar to the case
Data Source
AI summary
An improved capacitor packaging solution is presented that incorporates both thermal and electrical considerations. A package can include capacitor elements electrically coupled to a bus bar, and a thermally enhanced isolation layer between the bus bar and a case. The isolation layer can be provided adjacent a case base and sidewall portions. The bus bar can be disposed adjacent the isolation layer and be configured to extend along the package side and along the package length below the capacitor elements to provide an extended path for heat dissipation from the bus bar prior to its contact with capacitor elements. The enhanced isolation layer is configured to conduct heat away from the bus bar to the case to avoid the hotspot temperature of the capacitor. Reduced capacitor temperature allows use of smaller, cheaper capacitors, reducing inverter costs without compromising performance.