Power Conversion Device Vertical Inverter Capacitor Layout
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Solution Overview
Problem
Power conversion devices for electric vehicles face challenges in reducing the case width-to-height ratio while maintaining anti-vibration characteristics and minimizing bus bar inductance, especially when the inverter and capacitor are aligned vertically due to the cantilevered support of the capacitor, which degrades vibration resistance and increases assembly complexity.
Innovation Solution
The power conversion device employs a configuration where the inverter is fixed in the upper case and the capacitor is accommodated in the lower case, with parallel bus bars connecting them, allowing for easier assembly and reducing parasitic inductance by separating the bus bars' electrodes on side surfaces and using linear bus bars to minimize inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the inverter and capacitor are aligned vertically to reduce the case width-to-height ratio, then the case dimensions are optimized, but the capacitor's anti-vibration characteristic deteriorates due to cantilevered support
Solution Approach 1:
The patent transitions from horizontal alignment to vertical alignment of the inverter and capacitor, changing the spatial dimension of arrangement. This allows the case width-to-height ratio to be reduced while maintaining functional requirements through a different spatial configuration.
Solution Approach 2:
The case is divided into an upper case and a lower case, with the inverter fixed to the upper case and the capacitor fixed to the lower case. This segmentation allows each component to be independently positioned and supported, enabling the capacitor to be centered in the lower case for optimal vibration resistance while maintaining the compact vertical arrangement.
2Shape
If the inverter and capacitor are fixed to different cases (upper and lower) to reduce width-to-height ratio, then case dimensions are optimized, but assembly complexity increases
Solution Approach 1:
The inverter is preliminarily fixed to the upper case and the capacitor is preliminarily fixed to the lower case before final assembly. This preliminary positioning allows for easier connection of the bus bar between the inverter and capacitor, reducing the overall assembly complexity despite the vertical separation of components.
3Ease of manufacture
If the capacitor is supported at only the upper end in a cantilevered manner to simplify mounting, then mounting is simplified, but the anti-vibration characteristic becomes poor
Solution Approach 1:
Instead of supporting the capacitor at the upper end (conventional approach), the patent inverts the support strategy by fixing the capacitor to the lower case and centering it in the vertical direction. This inverted approach provides better vibration resistance by distributing support forces more effectively.
Solution Approach 2:
The support position is changed from the upper end (vertical extremity) to the center of the capacitor in the vertical direction. This dimensional repositioning transforms the support configuration from a cantilevered single-point support to a centered support that spans the capacitor's vertical dimension, significantly improving anti-vibration characteristics.
Data Source
AI summary
A power conversion device includes a case including an upper case and a lower case; an inverter that is accommodated in a first partial case and is fixed to the first partial case, the first partial case being one of the upper case and the lower case; and a capacitor that is connected to the inverter by a positive electrode bus bar and a negative electrode bus bar, the capacitor being disposed in an internal space of a second partial case that is another of the upper case and the lower case. The first partial case includes a fastening portion that extends from an internal space of the first partial case to the internal space of the second partial case. In the internal space of the second partial case, the capacitor is fastened to the fastening portion.