Power Converter Bus Bar Cooling to Protect Capacitor Heat Exposure
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Solution Overview
Problem
The capacitor in a power conversion device is affected by heat generation from the bus bars, which are power transmission paths, requiring an efficient cooling structure.
Innovation Solution
A power conversion device with a configuration that includes a power conversion circuit, positive and negative electrode bus bars, a capacitor connected to these bars, a metal base plate, and a housing with a refrigerant passage, where the thermal resistance from the capacitor to the refrigerant passage is greater than the thermal resistance from the bus bars to the refrigerant passage, thereby reducing the capacitor's exposure to bus bar heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the capacitor is placed near the bus bars for compact design, then the device structure is simplified, but the capacitor is exposed to heat generated by the bus bars
Solution Approach 1:
A base plate is introduced as an intermediary component between the capacitor and the bus bars. This base plate serves as a thermal barrier that blocks heat transfer from the bus bars to the capacitor, while still allowing the capacitor to be positioned close to the bus bars for compact design. The base plate acts as a mediator that maintains both the compact structure and the thermal protection.
2Volume of moving object
If the capacitor is positioned close to the bus bars, then the device occupies less space, but the capacitor is affected by heat generation of the bus bars
Solution Approach 1:
The base plate functions as a thermal shield or intermediary that allows the capacitor to be positioned close to the bus bars for space efficiency while blocking the harmful thermal effects. The base plate creates a thermal boundary that protects the capacitor from heat exposure without requiring increased separation distance.
3Object-affected harmful factors
If the thermal resistance from capacitor to refrigerant passage is increased to protect the capacitor from heat, then the capacitor is less affected by bus bar heat, but heat dissipation from the capacitor may be reduced
Solution Approach 1:
The base plate creates a localized thermal barrier specifically at the capacitor-bus bar interface, providing high thermal resistance where needed to protect the capacitor. Meanwhile, the refrigerant passage can still provide cooling to the base plate from the opposite side, maintaining local heat dissipation capability without compromising the thermal protection of the capacitor.
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 capacitor is less susceptible to heat generated by the bus bars, maintaining its effectiveness and reducing temperature rise.
Implementation Method 1
a thermal resistance from the capacitor to the refrigerant passage is larger than a thermal resistance from the positive electrode bus bar and the negative electrode bus bar to the refrigerant passage
Implementation Method 2
a thermal resistance from the capacitor to the refrigerant passage is larger than a thermal resistance from the positive electrode bus bar and the negative electrode bus bar to the refrigerant passage
Data Source
AI summary
A power conversion device includes: a power conversion circuit that converts DC power into AC power; a positive electrode bus bar and a negative electrode bus bar connected to the power conversion circuit; a capacitor connected to at least one of the positive electrode bus bar and the negative electrode bus bar; a base plate made of metal on which the capacitor is placed; and a housing in which the power conversion circuit, the capacitor, the base plate, the positive electrode bus bar, and the negative electrode bus bar are accommodated, and a refrigerant passage is formed, in which the positive electrode bus bar and the negative electrode bus bar are installed in the housing via a resin member having insulating property, and in which the base plate on which the capacitor is placed is installed in the housing, and a thermal resistance from the capacitor to the refrigerant passage is larger than a thermal resistance from the positive electrode bus bar and the negative electrode bus bar to the refrigerant passage.