DC Switch Pre-Charging Resistor Heat Sink Integration
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Solution Overview
Problem
Direct current (DC) networks connected via pre-charging resistors experience high equalizing currents, leading to excessive heat generation and potential damage when switched on and off repeatedly, as existing cooling solutions are inadequate for managing the heat produced by these resistors.
Innovation Solution
A DC switch design that incorporates a pre-charging resistor within a metallic heat sink with internal cooling ribs, where the resistor is positioned in a recess to direct heat dissipation away from surrounding electronics, combined with active ventilation and temperature regulation, ensuring efficient cooling even during repeated switching operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pre-charging resistor is used to limit equalizing currents when switching on DC networks, then the current level is controlled and component damage is prevented, but significant heat is generated that can damage surrounding electronics when switching operations are repeated frequently
Solution Approach 1:
The pre-charging resistor is extracted from the conventional location near power semiconductors and placed in a dedicated recess within the heat sink. This separation removes the heat-generating resistor from proximity to heat-sensitive electronics while maintaining its current-limiting function. The resistor is positioned in a cutout area of the heat sink that is optimized for heat dissipation away from other components.
Solution Approach 2:
The heat sink serves as an intermediary thermal management system between the pre-charging resistor and the surrounding environment. It provides a dedicated thermal pathway that conducts heat away from the resistor through thermally conductive material, preventing heat accumulation that would otherwise damage surrounding electronics during repeated switching operations.
2Device complexity
If the pre-charging resistor is placed near power semiconductors for compact design, then device size is reduced, but heat from the resistor can damage the power semiconductors and surrounding electronics
Solution Approach 1:
The heat sink is designed with non-uniform thermal properties - a dense array of cooling ribs in areas requiring high heat dissipation and a recessed area with modified thermal characteristics for the pre-charging resistor. This localized thermal management allows different regions of the heat sink to serve different functions: compact integration of components while providing targeted heat dissipation pathways that protect heat-sensitive areas.
3Temperature
If cooling channels are added to the heat sink to improve heat dissipation, then heat management is enhanced, but the structural integrity and space for other components are compromised
Solution Approach 1:
Instead of adding complex three-dimensional cooling channels that would compromise structural integrity, the solution uses a two-dimensional array of cooling ribs on the heat sink surface. These ribs extend from the base in a planar configuration that provides large surface area for convection and radiation heat dissipation without requiring deep internal channels, maintaining structural strength while enhancing thermal management.
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 solution effectively minimizes the risk of damage to other components by ensuring optimal heat dissipation directly through the heat sink, maintaining efficient cooling capacity during normal operation and preventing overheating, even with frequent switching.
Implementation Method 1
a metallic heat sink to cool the power semiconductor switch and the pre-charging resistor
Implementation Method 2
the heat sink comprises cooling channels formed by internal cooling ribs
Implementation Method 3
a pre-charging resistor to limit the current when switching on
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a direct current switch for coupling two direct current networks, a load-side direct current network particularly comprising load-side capacitors, said direct current switch comprising: one or more power semiconductor devices; a precharge resistor for current-limit control of switch-on processes; and a heat sink for extracting heat from the power semiconductor device and the precharge resistor, characterized in that the precharge resistor is located inside the heat sink in a recess in the heat sink.