Slip Ring Cooling Structure for High-Power Dynamoelectric Machines
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Solution Overview
Problem
Double-fed asynchronous machines in wind power plants face increasing thermal loads due to rising power outputs, leading to overheating issues in slip ring systems, which can compromise the operation of the generators.
Innovation Solution
The implementation of a hollow shaft with recesses for cooling medium flow, allowing for axial cooling of the feed lines to the rotor windings, and the use of a cavity within the slip ring system for cooling, enhance the cooling performance by targeting the thermal loads of both the brushes and the feed lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power output of the generator is increased, then the electrical performance is improved, but the thermal load on the slip ring system increases causing temperatures to exceed permissible maximums
Solution Approach 1:
The cooling system is segmented into multiple independent cooling circuits: one for the slip rings, one for the brushes, and one for the feed lines. This segmentation allows each component to be cooled independently and optimally, enabling the system to handle higher power outputs without thermal overload.
Solution Approach 2:
A cooling medium (air or liquid) is introduced as an intermediary to transfer heat away from the slip ring system components. The cooling medium flows through channels in the slip ring body and around the feed lines, absorbing thermal energy and carrying it away to maintain permissible operating temperatures.
2Temperature
If the surfaces of slip ring components are increased to reduce temperatures, then the cooling performance is improved, but the device complexity and size increase
Solution Approach 1:
The cooling functions for the slip rings, brushes, and feed lines are merged into a single integrated cooling system. The cooling medium flows through a unified system of channels and passages that serve multiple components simultaneously, reducing overall system complexity while maintaining effective cooling of all thermal hotspots.
Solution Approach 2:
The cooling system is designed with multi-functionality, where the same cooling medium and cooling structure serve multiple purposes: cooling the slip rings through internal channels, cooling the brushes through air circulation, and cooling the feed lines through passages in the hollow shaft. This universal cooling approach avoids the need for separate cooling systems for each component.
3Temperature
If a fan is added to ensure air circulation for cooling, then the cooling performance is improved, but the device complexity increases
Solution Approach 1:
The cooling system is designed to be partially self-service, where the rotation of the slip rings and feed lines through the cooling medium creates natural convection currents that enhance cooling without requiring additional active components. The hollow shaft structure and cooling channels are positioned to utilize the rotational motion itself to drive cooling airflow.
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 significantly reduces the temperatures of the slip ring body, shaft, and conductors, enabling higher power outputs with the same components in the same installation space, while preventing overheating and ensuring reliable operation.
Implementation Method 1
recesses (bores) are provided on the cavity axially on the inside and axially on the outside, through which recesses a cooling medium flow (gas, liquid or preferably cooling air) can be introduced axially into the cavity and can be discharged into an outlet region
Implementation Method 2
a fan in the slip ring housing ensures air circulation, by air being conducted from outside (interior space of the nacelle) through the entire slip ring system and therefore ensuring the necessary cooling of the system
Implementation Method 3
the shaft is a hollow shaft at least in the region of the slip ring system, in the hollow shaft portion of which, which is assigned to the slip ring system, the feed lines to the winding system of the rotor are routed
Data Source
AI summary
A dynamoelectric machine includes a shaft, a rotor arranged fixedly on the shaft for conjoint rotation, and a slip ring system enabling a rotor winding system to be contacted electrically and including a slip ring body having slip rings arranged spaced-apart axially behind one another and assigned to an electrical phase. The slip ring body is connected fixedly to the shaft for conjoint rotation and has between an inner side thereof and the shaft a section which forms an axially open cavity on both skies. In a region of the slip ring system, the shaft is hollow with a hollow shaft portion assigned to the slip ring system for routing feed lines to the rotor winding system. Recesses are provided on the cavity axially on an inside and axially on an outside for introducing a cooling medium flow axially into the cavity and discharge thereof into an outlet region.