Variable Frequency Drive Heat Sink Assembly Cooling
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Solution Overview
Problem
Variable frequency drives in transport refrigeration units face challenges in cooling their power electronics effectively, especially in varying operational environments and power consumption levels, which affects reliability and performance.
Innovation Solution
A variable frequency drive heat sink assembly is designed with a sealed enclosure and a heat sink structure that directs cooling air flow over an external heat transfer surface, using a fan to maintain the power electronics at a safe temperature while isolating them from corrosive ambient conditions, featuring a housing with an interior chamber and an exterior flow channel with arcuate heat transfer fins for efficient heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the power electronics are exposed to ambient conditions for direct cooling, then cooling efficiency is improved, but reliability deteriorates due to corrosive environmental exposure
Solution Approach 1:
The patent introduces a heat sink as an intermediary component between the power electronics and ambient environment. The heat sink receives cooling air through its exterior surface, transfers heat away from the power electronics via its thermally conductive structure, and dissipates heat to the environment through its external fins, thereby protecting the power electronics from direct exposure to corrosive ambient conditions while maintaining effective cooling
Solution Approach 2:
The housing is segmented into distinct functional zones: an interior chamber for enclosing the power electronics, an exterior flow channel for air circulation, and a heat sink structure with separate heat transfer regions. This segmentation allows the cooling function to be separated from the environmental exposure function, enabling the power electronics to be protected while still achieving effective heat dissipation
2Reliability
If a sealed enclosure is used to protect power electronics, then reliability is improved, but cooling efficiency deteriorates
Solution Approach 1:
The heat sink extends in the external dimension beyond the sealed housing, with its heat transfer surface positioned in the exterior flow channel. This dimensional extension allows the heat sink to access cooling air from the external environment while the power electronics remain protected within the sealed interior chamber, effectively adding a thermal exchange dimension without compromising environmental protection
3Temperature
If cooling air flow is directed over the power electronics, then cooling is improved, but corrosion from ambient conditions worsens
Solution Approach 1:
The heat sink acts as a mediator that intercepts cooling air flow before it reaches the power electronics. The cooling air passes over the heat sink's external heat transfer surface, absorbing heat from the power electronics through the heat sink structure, while the power electronics remain isolated within the sealed interior chamber, thus achieving cooling without corrosive exposure
4Temperature
If the heat sink structure is exposed to ambient air flow, then heat dissipation is improved, but the structure becomes vulnerable to corrosive environmental factors
Solution Approach 1:
The heat sink structure is merged with the housing to form an integrated assembly where the heat sink's external heat transfer surface is positioned within the exterior flow channel but remains part of the sealed enclosure system. This merging allows the heat sink to benefit from ambient air flow for heat dissipation while being structurally integrated into the protective housing, shielding it from direct corrosive environmental attack
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 cools the power electronics of the variable frequency drive to maintain them below a specified threshold temperature, ensuring reliability and protecting them from corrosive environments, while allowing for efficient operation across a wide range of conditions.
Implementation Method 1
a heat sink structure disposed in conductive heat transfer relationship with said interior chamber and having a heat transfer surface positioned within said exterior flow channel
Implementation Method 2
passing a flow of cooling air through said exterior channel across and over said heat transfer surface of said heat sink structure
Implementation Method 3
a fan in operative association with said housing for passing a flow of cooling air through said exterior channel across and over said heat transfer surface
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A heat sink assembly is disclosed for cooling a power electronics module, such as a variable frequency drive. The heat sink assembly includes a housing and a heat sink structure. The housing defines an interior chamber for enclosing the power electronics module and also defines a cooling air flow channel exterior to the interior chamber. The heat sink structure is disposed in conductive heat transfer relationship with the interior chamber and has a heat transfer surface positioned within the exterior cooling air flow channel in convective heat transfer relationship with the cooling air flow.