External Serpentine Coolant Pipe for Electric Motor Thermal Management
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Solution Overview
Problem
Conventional cooling systems for high power density electric machines are expensive and difficult to manufacture, requiring cost-effective alternatives.
Innovation Solution
A fluid-cooled electric machine design featuring a serpentine coolant pipe with heat conduction elements, such as plates or cups, positioned outside the stator lamination stack to efficiently carry heat away from the coils, using external grooves on the stator core and a housing to retain the pipe assembly, with insulation to prevent electrical shorting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cast metal housings with internal fluid cooling channels are used, then cooling capability is achieved, but manufacturing cost and difficulty increase
Solution Approach 1:
The cooling system is segmented into separate components: external coolant pipes positioned outside the stator core, and separate heat conduction plates or cups that contact the stator teeth. This segmentation allows each component to be manufactured independently using simpler processes, avoiding the need for complex internal cooling channels within the housing.
Solution Approach 2:
The coolant pipes are extracted from the internal housing structure and repositioned externally around the stator core. The heat conduction function is extracted and implemented through separate plates or cups that contact the stator teeth. This extraction simplifies manufacturing while maintaining cooling effectiveness.
2Temperature
If coolant pipes are positioned inside the stator core, then heat transfer is direct, but eddy current losses increase and manufacturing complexity increases
Solution Approach 1:
The coolant pipes are taken out from the internal stator core position and repositioned externally. Heat conduction plates or cups serve as intermediaries to transfer heat from the stator teeth to the external pipes, eliminating direct internal pipe placement that causes eddy currents while maintaining effective heat transfer.
Solution Approach 2:
Heat conduction plates or cups are introduced as intermediary components between the stator teeth and the external coolant pipes. These intermediaries efficiently conduct heat away from the stator while avoiding the eddy current losses associated with internal pipe placement.
3Loss of energy
If coolant pipes are placed outside the stator core, then eddy current losses are reduced, but heat transfer path length increases
Solution Approach 1:
Heat conduction plates or cups are positioned at specific locations where stator teeth protrude externally, creating localized high-quality thermal contact points. This ensures that even though pipes are external, the heat transfer path remains short and efficient at the critical heat generation locations.
4Temperature
If internal cooling channels are used in cast metal housings, then cooling is integrated, but developmental and recurring costs increase
Solution Approach 1:
The cooling system is divided into modular segments: external pipes, heat conduction plates/cups, and stator core components. This modular segmentation reduces developmental costs by allowing independent optimization of each component and reduces recurring costs through simplified manufacturing and assembly processes.
Solution Approach 2:
The external pipe configuration with heat conduction plates serves multiple functions: cooling the stator, providing structural support, and allowing flexible positioning. This multi-functionality reduces the need for additional specialized components, lowering both developmental and manufacturing costs.
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 effectively reduces eddy current losses and manufacturing costs while maintaining superior cooling efficacy for electric motors, generators, and motor/generators by positioning the coolant tube outside the magnetic circuit, thus avoiding corrosion risks and enhancing heat transfer.
Implementation Method 1
heat conduction elements are secured to the end turns of the coolant pipe
Implementation Method 2
fluid cooled electric machine design featuring a serpentine coolant pipe
Implementation Method 3
A layer of electrically non-conductive material preferably coats the pipe and the plates or cups to insulate the copper end turns from the plates or cups
Data Source
AI summary
The stator of a fluid cooled electric machine, such as a motor, a generator, or a motor/generator assembly, includes an annular stator core including inwardly projecting teeth and external grooves in an outer surface of the core that are radially aligned with the teeth. Electrically conductive windings are mounted on the inwardly projecting teeth, and a pipe assembly for coolant has a pipe formed into a serpentine shape. The pipe includes axially extending pipe portions received in the external stator core grooves, and end turns interconnecting adjacent pairs of the axially extending pipe portions. Heat conduction elements are secured to the end turns of the coolant pipe, and a housing surrounding the outer surface of the stator core retains the axially extending pipe portions within the external grooves.