Power Converter Bus Bar Layout for Capacitor Heat Isolation
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Solution Overview
Problem
In power conversion devices for vehicles, the direct mounting of mold bus bars on flow path forming bodies leads to short spatial and creepage distances, causing excessive heat buildup and temperature rises in smoothing capacitors, which can exceed their heat-resistant limits.
Innovation Solution
A power conversion device design featuring a case with a partitioned semiconductor module housing and a connection member with a resin portion and conductor, where a protruding thermal coupling portion is placed between exposed terminal portions, increasing spatial and creepage distances and reducing heat transfer to capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the mold bus bar is directly mounted on the flow path forming body to conduct heat, then heat dissipation efficiency is improved, but the spatial distance and creepage distance become too short causing capacitor temperature to exceed heat-resistant limits
Solution Approach 1:
The connection member is divided into distinct functional portions: a first connection portion for electrical connection to the power semiconductor module, and a second connection portion for thermal connection to the flow path forming body. This segmentation allows the electrical and thermal connection functions to be separated spatially, increasing the distance between the bus bar terminal and the capacitor while maintaining effective heat dissipation through the dedicated thermal path.
Solution Approach 2:
The connection member acts as an intermediary element between the power semiconductor module and the flow path forming body. It provides a dedicated thermal conduction path through its thermal connection portion while maintaining electrical connection through its electrical connection portion. This intermediary structure enables heat to be conducted away from the bus bar through a controlled path that does not directly expose the capacitor to high temperatures.
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 design effectively increases the spatial and creepage distances between the connection member and semiconductor modules, suppressing capacitor temperature rises and preventing overheating.
Implementation Method 1
the protruding portion is thermally coupled to the connection member and disposed between a first root portion of an exposed portion where the first terminal portion is exposed from the resin portion and a second root portion of an exposed portion where the second terminal portion is exposed from the resin portion
Data Source
AI summary
A negative-side bus bar 41 includes a capacitor connection portion and first and second negative terminal portions 271 exposed from a resin portion 44 and connected to a DC negative-side terminals 103 of first and second power semiconductor modules 30. A partition portion 252b of a case 252 is provided with a protruding portion 281 that protrudes toward a mold bus bar 40 further than an upper surface 257 of the first and second power semiconductor modules 30 and is thermally coupled to the mold bus bar 40. The projecting portion 281 is disposed between a root portion 275 of an exposed portion where the first negative electrode terminal portion 271 is exposed from the resin portion 44 and a second root portion 275 of an exposed portion where the second negative electrode terminal portion 271 is exposed from the resin portion 44. In this manner, a spatial distance and a creepage distance between the exposed portion from the resin portion of the mold bus bar and the power semiconductor module are made large and the temperature rise of a capacitor is suppressed.