Stator Cooling Passageways in Electrical Machines
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Solution Overview
Problem
High-power electrical machines face challenges in efficiently managing heat generated from resistive losses in stator winding conductors, leading to increased temperature and potential insulation failure, with existing cooling methods compromising on power density, mechanical complexity, and noise.
Innovation Solution
The design incorporates axially extending cooling passageways within stator teeth and a closed-loop cooling circuit, utilizing a manifold system and non-electrically conductive tubes to circulate cooling fluid, which enhances heat transfer and maintains mechanical simplicity while minimizing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If direct liquid or air cooling is used, then cooling efficiency is improved, but mechanical complexity increases
Solution Approach 1:
The cooling passageways are merged with the stator teeth structure itself, integrating the cooling function into the existing magnetic circuit components. This eliminates the need for separate cooling mechanisms while maintaining effective heat removal from the stator winding conductors.
Solution Approach 2:
The stator teeth structure serves dual purposes: it provides the magnetic circuit path and simultaneously houses the cooling passageways. The cooling system utilizes the existing structural components (stator teeth and slots) to provide cooling, making the system self-sufficient without requiring additional complex cooling machinery.
2Temperature
If external water jacket cooling is used, then cooling efficiency is improved, but noise increases
Solution Approach 1:
The cooling function is merged with the stator core structure, eliminating the need for separate external water jackets and associated pumps or fans that generate noise. The cooling passageways are formed within the laminations themselves, creating a quiet cooling system.
Solution Approach 2:
The patent replaces complex mechanical cooling systems (external water jackets, pumps, fans) with a simplified internal cooling passage system that uses the natural flow of cooling fluid through the stator teeth, significantly reducing mechanical noise generation.
3Temperature
If cooling passageways are added to stator teeth, then heat transfer is enhanced, but manufacturing complexity increases
Solution Approach 1:
The stator core is segmented into multiple laminations, each containing cooling passageways. This segmentation allows the cooling passages to be formed during the standard lamination manufacturing process, and the segments are then stacked to form the complete stator core, simplifying the overall manufacturing process.
Solution Approach 2:
The laminations are designed to serve multiple functions simultaneously: providing the magnetic circuit path, containing the cooling passageways, and supporting the stator winding conductors. This multi-functionality reduces the need for additional manufacturing steps and components.
4Power
If high power density is achieved, then output power is increased, but temperature increases leading to insulation failure
Solution Approach 1:
The harmful heat generated by high power density operations is extracted from the stator winding conductors through the cooling passageways embedded in the stator teeth. The cooling fluid flowing through these passageways removes heat directly at the source, preventing temperature buildup that would lead to insulation failure.
Solution Approach 2:
A cooling fluid is introduced as an intermediary substance to transfer heat away from the stator winding conductors. The cooling fluid flows through the passageways in the stator teeth, absorbing heat from the conductors and carrying it away, thereby maintaining safe operating temperatures even at high power densities.
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 provides efficient cooling of stator winding conductors and endwindings, maintaining low acoustic signature and high power density, and is robust against external vibrations and shock loads, with improved manufacturing and maintenance benefits.
Implementation Method 1
cooling passageways through which a cooling fluid flows in use
Implementation Method 2
circulate cooling fluid... enhances heat transfer
Data Source
AI summary
A stator for an electrical machine (e.g., a motor or generator) is described. The stator includes a stator core consisting of a plurality of axially adjacent generally annular laminations. The stator has axially extending stator teeth between adjacent pairs of which are formed axially extending stator slots for receiving conductors of a stator winding. At least one of the stator teeth includes an axially extending cooling passageway through which a cooling fluid flows in use. The electrical machine can include means for circulating cooling fluid through the cooling passageway(s) to cool the stacked laminations and means for circulating air around the stator along an air cooling circuit where the circulated air is cooled by the stator laminations and there is no need for a separate heat exchanger.