Embedded Rotor Cooling Tubes for Low-Windage Winding Heat Removal
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Solution Overview
Problem
Traditional liquid cooling methods for electrical machine rotors, such as end spray cooling, increase windage losses and reduce efficiency, leading to higher rotor winding temperatures and shorter mean time between failures (MTBF), which limits power density and cooling effectiveness.
Innovation Solution
The integration of cooling tubes within the rotor winding gaps, intermingled with conductor strands and constrained to resist centrifugal forces, allows for direct conduction cooling without liquid in the air gap, maintaining efficiency and reducing windage losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If end spray cooling is used to cool the rotor, then cooling effectiveness is improved, but windage losses increase by about 100%
Solution Approach 1:
The invention extracts the cooling function from the air gap environment and relocates it to embedded cooling conduits within the rotor structure. This removes the harmful liquid coolant from the air gap, eliminating the windage loss penalty while preserving the cooling capability through direct conduction paths from the windings to the coolant.
Solution Approach 2:
The invention introduces thermal conduction as an intermediary mechanism between the rotor windings and the coolant. Instead of direct liquid cooling in the air gap, heat is transferred through solid conduction paths (cooling conduits) that are embedded in the rotor, providing efficient heat removal without the harmful effects of liquid presence in the air gap.
2Device complexity
If conventional cooling methods are used, then simplicity is maintained, but power density increases are limited by cooling effectiveness
Solution Approach 1:
The invention nests the cooling conduits within the existing rotor structure, embedding them in the rotor poles or rotor yoke. This nested integration allows the cooling function to be added without significantly increasing overall device complexity, while enabling improved cooling effectiveness that supports higher power density.
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 solution enhances electrical machine efficiency and extends MTBF by providing effective cooling through direct conduction, reducing windage losses and maintaining a dry air gap, thus addressing the limitations of traditional cooling methods.
Implementation Method 1
allows for direct conduction cooling without liquid in the air gap
Implementation Method 2
A first end of the cooling tube is connected in fluid communication with an inner flow passage of the inner shaft. A second end of the cooling tube can be connected in fluid communication with an inner flow passage of the outer shaft
Data Source
AI summary
A rotor for an electrical machine includes a core including a plurality of rotor poles circumferentially spaced apart from one another about a hub. A winding is wound about the rotor poles. The winding passes longitudinally through a respective winding gap between each circumferentially adjacent pair of rotor poles. A cooling tube extends through at least one of the respective winding gaps.