Power Converter Busbar Shielding for Capacitor Thermal Management
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Solution Overview
Problem
Conventional power converters inadequately restrict the temperature increase of smoothing capacitors due to incomplete heat management from discharge resistors, allowing heat convection and radiation to contribute to capacitor temperature rise.
Innovation Solution
The power converter design includes a pair of positive and negative busbars arranged between the discharge resistor and the smoothing capacitor, effectively shielding the capacitor from heat convection and radiation and reducing heat conduction by using busbars with high heat capacity to absorb and dissipate heat generated from the discharge resistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the discharge resistor is connected via positive and negative busbars to discharge electrical charge from the smoothing capacitor, then the capacitor can be safely discharged, but heat generated from the discharge resistor is conducted to the smoothing capacitor through the busbars causing temperature increase
Solution Approach 1:
A heat-resistant member (insulating member) is introduced as an intermediary between the discharge resistor and the smoothing capacitor. This member has lower thermal conductivity than the busbars, thereby blocking the heat conduction path from the discharge resistor to the smoothing capacitor while still allowing the discharge function to operate through the busbars.
2Temperature
If conventional heat management is used addressing only heat conduction, then heat conduction is partially managed, but heat convection and radiation from the discharge resistor still contribute to capacitor temperature rise
Solution Approach 1:
The heat-resistant member serves as a multi-functional intermediary that simultaneously addresses heat conduction, heat convection, and heat radiation. By positioning this member between the discharge resistor and smoothing capacitor, it blocks conductive heat transfer through its low thermal conductivity, and also shields the capacitor from convective and radiative heat transfer, thereby managing all three heat transfer mechanisms with a single component.
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 configuration efficiently restricts the temperature rise of the smoothing capacitor by shielding it from heat convection, radiation, and conduction, thereby enhancing thermal management and preventing excessive heat transfer.
Implementation Method 1
The heat conduction shows that a first component of the heat generated from the discharge resistor is transferred to the smoothing capacitor through the pair of positive and negative busbars that directly connect between the discharge resistor and the smoothing capacitor.
Implementation Method 2
Heat convection shows that a second component of the heat generated from the discharge resistor is transferred to the smoothing capacitor by air convection around the power converter.
Implementation Method 3
The heat radiation shows that a third component of the heat generated from the discharge resistor is transferred to the smoothing capacitor by radiation.
Data Source
AI summary
In a power converter, a semiconductor module incorporates therein a semiconductor element constituting a power converter circuit. A smoothing capacitor is configured to smooth a direct-current voltage applied to the semiconductor module. A pair of positive and negative busbars is configured to electrically connect the semiconductor module and the smoothing capacitor. The positive and negative busbars are arranged to face each other with a predetermined space therebetween. A discharge resistor is connected in parallel with the smoothing capacitor via the positive and negative busbars, and is configured such that an electrical charge stored in the smoothing capacitor flows through the discharge resistor as a discharge current. The positive and negative busbars are interposed between the discharge resistor and the smoothing capacitor.