Capacitor End-Face Cooling via Bus Bar Contact
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Solution Overview
Problem
Existing electric power converters face challenges in effectively cooling capacitors due to increased equivalent series resistance (ESR) and heat generation, which limits the cooling performance and increases the temperature of capacitors, especially when downsized.
Innovation Solution
The electric power converter design includes a capacitor with end-face-electrodes on both end faces connected to bus bars, allowing for surface contact with a cooling member, thereby shortening the heat transfer distance and improving cooling efficiency, while the bus bars also help in dissipating heat generated by semiconductor modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the capacitor is downsized, then the size of the electric power converter is reduced, but the ESR value increases causing the capacitor to generate more heat
Solution Approach 1:
The patent changes the cooling approach from bottom surface contact to end-face-electrode contact. By utilizing the end-face-electrodes (metallikon surfaces) as cooling interfaces instead of the bottom surface, the heat dissipation pathway is shifted to a different dimension, enabling effective cooling of downsized capacitors with higher ESR
2Temperature
If the capacitor is mounted on the heat sink with bottom surface contact, then cooling is provided, but the cooling performance is insufficient for downsized capacitors
Solution Approach 1:
Instead of cooling the capacitor from the bottom surface as conventionally done, the patent inverts the cooling approach by utilizing the end-face-electrodes as the primary cooling interface. This reversal enables direct heat extraction from the electrodes that are already connected to the internal electrode structure, providing superior cooling performance
3Temperature
If heat is transmitted through bus bars from semiconductor modules, then the capacitor temperature may rise, but the bus bars can also be used for cooling the capacitor
Solution Approach 1:
The bus bars are given dual functionality: they continue to transmit current from the semiconductor modules while simultaneously serving as heat dissipation pathways. By contacting the end-face-electrodes, the bus bars extract heat from the capacitor, converting a potential heat transmission pathway into an active cooling mechanism
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 enhances the overall cooling performance of the capacitor by efficiently transferring heat from the capacitor to the cooling member, reducing the ESR and suppressing temperature rise, thus improving the thermal management of the power converter.
Implementation Method 1
the heat inside the element body of the capacitor is transferred to the end-face-electrodes through the internal electrode having high thermal conductivity
Implementation Method 2
The end-face-electrode facing the cooling member is in contact with the cooling member via the bus bar
Data Source
AI summary
An electric power converter includes a semiconductor module constituting a power conversion circuit, a capacitor electrically connected to the semiconductor module, and a cooling member for cooling the capacitor. The capacitor includes an element body provided with internal electrode, and a pair of end-face-electrodes provided on both end faces of the element body and connected to the internal electrode. The pair of end-face-electrodes are connected with a pair of bus bars, respectively, in a manner of surface contact. The capacitor is disposed in a state where one of the pair of end-face-electrodes is facing the cooling member. The end-face-electrode facing the cooling member is in contact with the cooling member via the bus bar.