Electric Machine Stator Thermal Management via Segmented Core
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Solution Overview
Problem
Existing electric motor stators face inefficiencies in heat elimination, particularly in sealed types, leading to increased resistance and energy dissipation due to inadequate cooling of windings, which is critical in automotive applications where high power and efficiency are required.
Innovation Solution
A stator design featuring a compact ferromagnetic core with a circular crown and radial teeth, combined with self-supporting coils and an overmoulded insulation system, enhances heat exchange by increasing the wire's surface area in contact with the casing, allowing for more effective thermal conductivity and reduced magnetic flux density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the windings are sealed in the container with casing and cap, then the motor structure is compact and sealed, but heat elimination becomes inadequate leading to higher resistance and energy dissipation
Solution Approach 1:
The stator core is segmented into multiple superposed annular plates, creating a multi-layered structure that increases the surface area for heat dissipation while maintaining the sealed configuration. This segmentation allows heat to be conducted through multiple interfaces between plates and the casing.
Solution Approach 2:
The invention transitions from a conventional single-block stator structure to a multi-dimensional stacked plate configuration. This dimensional change creates additional heat transfer pathways through the axial direction, enabling more effective thermal management within the sealed volume without requiring increased radial or tangential space.
2Power
If high electrical current flows through the winding, then power output increases, but heat generation increases leading to higher resistance and unacceptable energy dissipation
Solution Approach 1:
The invention converts the harmful heat generated by high current into a manageable thermal flow by designing dedicated heat transfer pathways. The thermal contact between winding outer surface, spacer, and casing base wall transforms the waste heat into a controlled thermal conduction process that prevents energy loss while maintaining high power output capability.
Solution Approach 2:
A thermally conductive spacer is introduced as an intermediary element between the winding and the casing base wall. This spacer mediates the heat transfer process, providing a controlled thermal pathway that efficiently conducts heat away from the windings while maintaining electrical insulation and mechanical positioning.
3Adaptability or versatility
If conventional stator structure with multiplicity of copper wire coils is used, then winding flexibility is maintained, but heat exchange with casing is insufficient
Solution Approach 1:
The invention implements preliminary thermal management by pre-establishing heat transfer pathways through the spacer and thermal paste application before operation. The outer surface of the windings is positioned in advance to be in direct thermal contact with the spacer, ensuring immediate heat dissipation capability from the start of operation rather than relying on passive convection.
Solution Approach 2:
The invention applies local quality enhancement by concentrating thermal management resources at the critical heat generation zones. The thermally conductive paste is selectively applied at the interface between the winding outer surface and the spacer, creating localized high-efficiency heat transfer paths where they are most needed, rather than uniformly treating the entire motor structure.
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 design improves heat dissipation by up to 50% compared to prior art, increasing power output and efficiency while minimizing the need for parallel connections, reducing coil resistance, and enhancing torque performance.
Implementation Method 1
The spacer is thermally conductive and electrically insulating... A thermally conductive and electrically insulating paste is interposed between the coils and the spacer to fill any empty spaces... in order to maximize and optimize heat exchange between the coils, the spacer and the motor casing
Implementation Method 2
The spacer is thermally conductive and electrically insulating... A thermally conductive and electrically insulating paste is interposed between the coils and the spacer
Implementation Method 3
The electrical current flowing through the winding may be high and, on account of the Joule effect, produces heat which propagates to the entire winding and to adjacent parts of the electric machine
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A stator with concentrated windings comprises a ferromagnetic core having a central axis, an electrical insulation system disposed on the ferromagnetic core and a winding disposed on the insulation system to be mechanically locked thereto and electrically insulated from the ferromagnetic core (2); the ferromagnetic core (2) comprises a plurality of radial teeth (4a) without pole shoe and each tooth (4a) has a radial length, an axial depth and a width orthogonal to the radial length and axial depth; the ratio between the slot pitch and the width of the tooth (4a) is between 1.2 and 1.5, preferably between 1.3 and 1.4.