Electrical Machine Heat Sink for End Winding Cooling
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Solution Overview
Problem
Existing cooling methods for stator end windings in electrical machines are inadequate, as they fail to effectively manage heat transfer due to trapped vapor layers formed by boiling coolant, leading to reduced thermal performance and potential material failure.
Innovation Solution
A heat sink is introduced to increase the surface area for heat transfer, featuring a configuration that allows vapor bubbles to escape, such as a row of elongate members or a foraminous structure, and optionally an intermediary heat conductor like MgO to prevent electromagnetic interference, enhancing thermal contact with the end winding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cooling jacket is used to cool the stator body, then the main body cooling is improved, but the end winding cooling remains ineffective
Solution Approach 1:
The cooling system is segmented into two distinct parts: a cooling jacket for the stator body and a separate heat sink structure for the end windings. This segmentation allows each component to be optimized for its specific cooling requirements, with the heat sink providing direct thermal contact with the end winding regions that the cooling jacket cannot reach.
Solution Approach 2:
The cooling approach transitions from a two-dimensional cooling jacket surface to a three-dimensional heat sink structure that extends into the end winding region. The heat sink comprises a plurality of elongate members arranged to provide thermal contact with end windings from multiple directions, effectively adding a spatial dimension to the cooling coverage.
2Loss of energy
If coolant is used for cooling, then heat removal is improved, but trapped vapor layers reduce heat transfer effectiveness
Solution Approach 1:
The heat sink incorporates a porous or foraminous structure among the elongate members, allowing coolant to penetrate through the structure and contact end windings from multiple points. This porous configuration prevents vapor layer formation by enabling direct coolant access to hot spots while maintaining high surface area for heat transfer.
Solution Approach 2:
The system utilizes hydraulic principles by allowing coolant to flow through and around the heat sink structure, using fluid pressure and flow dynamics to displace vapor layers and ensure continuous liquid contact with heated surfaces. The coolant circulation system maintains positive pressure to prevent vapor trapping.
3Temperature
If surface area for heat transfer is increased, then thermal management is improved, but device complexity increases
Solution Approach 1:
The heat sink structure serves multiple functions simultaneously: it provides thermal contact with end windings, acts as a support structure for the windings, and creates channels for coolant flow. This multi-functionality increases surface area for heat transfer without proportionally increasing device complexity, as a single component performs multiple roles.
Solution Approach 2:
The heat sink combines several functional elements into a single integrated structure: thermal conduction paths, structural support, and coolant flow channels are merged into one component. This consolidation achieves high surface area for heat transfer while minimizing the number of separate parts and assembly steps.
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 heat sink improves thermal management of end windings by preventing vapor layer formation, thereby enhancing heat transfer and reducing temperature fluctuations, and can be retrofitted to existing machines for improved thermal performance.
Implementation Method 1
The heat sink can increase the surface area available for heat transfer, improving thermal management of the end winding by the coolant bath
Implementation Method 2
improving thermal management of the end winding by the coolant bath
Implementation Method 3
helping to avoid any bubbles formed by boiling coolant developing into a trapped vapour layer
Implementation Method 4
allows vapor bubbles to escape
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An electrical machine has a stator carrying electrical windings which protrude at opposite ends of the stator to form respective, ring-shaped end windings. The electrical machine further has a rotor having a plurality of magnetic field-producing elements for producing a rotor magnetic field which interacts with a stator magnetic field produced by the windings. The electrical machine further has a coolant bath for holding liquid coolant. The electrical machine further has a heat sink in thermal contact with at least one of the end windings, the bath and the heat sink being configured such that the heat sink is immersed in the coolant held in the bath. The heat sink defines one or more fluid pathways configured such that vapour bubbles, formed when coolant in contact with the heat sink boils, escape by rising through the heat sink.