Case Mold Capacitor Bus-Bar Overlap for Low Loss
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Solution Overview
Problem
Conventional case mold type capacitors used in hybrid electric vehicles (HEVs) face challenges in meeting high withstand voltage requirements with low loss, and their design complexity and insulation reliability issues, particularly with the connection of end-face electrodes and metalized films of varying widths, which affects performance and shape optimization.
Innovation Solution
The capacitor is designed with multiple metalized film capacitors divided into blocks, using overlapping bus-bars to reduce resistance and enhance heat dissipation, and a structure where P-pole and N-pole bus-bars are connected to form efficient external terminals, allowing for a smaller, lighter, and more reliable capacitor with improved insulation reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple metalized film capacitors are connected in parallel with bus bars to increase capacitance and withstand voltage, then the capacitance and withstand voltage are improved, but the loss increases due to longer wiring distance and higher resistance
Solution Approach 1:
The capacitor is divided into multiple blocks, each containing metalized film capacitors connected in parallel. This segmentation allows the bus bars to be positioned closer to each capacitor element, reducing the wiring distance and resistance within each block while maintaining the overall high capacitance through parallel connection of multiple blocks.
Solution Approach 2:
The patent transitions from a single-plane arrangement to a three-dimensional block structure. Multiple blocks are stacked vertically with bus bars extending between them, utilizing the vertical dimension to reduce horizontal wiring distance and resistance while achieving the required capacitance through parallel connection.
2Volume of moving object
If metalized film capacitors are arranged in a compact configuration to reduce size, then the volume is reduced, but the heat dissipation becomes insufficient
Solution Approach 1:
The capacitor is segmented into multiple blocks that can be arranged in a compact vertical stack. Each block contains its own bus bars and capacitor elements, allowing heat to be distributed across multiple smaller units rather than concentrated in a single large structure, improving overall heat dissipation efficiency.
Solution Approach 2:
The bus bars serve as thermal intermediaries, conducting heat away from the capacitor elements. By positioning bus bars close to capacitor elements and extending them between blocks, the patent creates efficient thermal pathways that facilitate heat dissipation from the compact internal structure.
3Adaptability or versatility
If end-face electrodes are connected to bus bars with varying widths to accommodate different capacitor specifications, then the adaptability is improved, but the design complexity and insulation reliability issues increase
Solution Approach 1:
The bus bar structure is designed with universal connection features that can accommodate different capacitor specifications. The bus bars include positioning protrusions and recesses that work with various capacitor widths, allowing the same basic structure to adapt to different capacitor element dimensions without requiring completely different designs.
Solution Approach 2:
While maintaining overall structural universality, the patent applies local quality variations through positioning protrusions and recesses at specific locations. These localized features enable adaptation to different capacitor widths while keeping the main bus bar structure simple and consistent, reducing overall design complexity.
Data Source
AI summary
A case mold type capacitor is formed of multiple metalized film capacitors connected together in parallel and rigidly accommodated with molding resin within a case. The multiple metalized film capacitors are divided into a first block and a second block, and P-poles of each block confront each other, and N-poles thereof also confront each other. Bus-bars including a connection terminal for external connection at an end are connected to respective P-poles and N-poles of each block. The bus-bars connected to the P-poles are coupled together, and the bus-bars connected to the N-poles are coupled together. Each one of the bus-bars includes a section located on the opening side of the case with respect to the blocks. The bus-bars connected to the P-poles overlap in part, and the bus-bars connected to the N-poles also overlap in part.