Micro-channel Heat Exchanger in Stator Core for Motor Cooling
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Solution Overview
Problem
Conventional electric motors and generators face inefficiencies in heat dissipation due to the generation of heat through friction, resistive heating, and magnetic losses, which can lead to performance degradation and potential malfunction if not adequately addressed.
Innovation Solution
The integration of a micro-channel heat exchanger within the stator core, formed by strategically arranging cooling apertures in laminations to create a large axial manifold and small angular micro-channels, allows for efficient coolant flow and heat dissipation, enhancing the cooling efficiency by increasing the surface area and reducing pressure requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional cooling systems are used for motors and generators, then the structure is simple, but the heat dissipation efficiency is insufficient leading to performance degradation
Solution Approach 1:
The micro-channel heat exchanger is nested within the stator core by forming cooling apertures directly in the laminations. The heat exchanger channels are integrated into the core structure itself, with manifolds positioned radially inboard of the outer peripheral surface and micro-channels extending through the lamination stack, creating a nested configuration that maximizes heat dissipation while minimizing additional structural complexity
Solution Approach 2:
The cooling system transitions from conventional external or surface cooling to internal volumetric cooling by creating three-dimensional micro-channels within the lamination stack. The channels extend in multiple dimensions including axial length, radial depth, and angular positioning, with manifolds arranged radially inboard and micro-channels connecting to radially outward regions, enabling heat removal from previously inaccessible internal volumes
2Loss of energy
If the surface area of the heat exchanger is increased, then the heat dissipation efficiency improves, but the pressure required to drive the flow increases
Solution Approach 1:
The heat exchanger is segmented into multiple parallel micro-channels distributed throughout the lamination stack. Each micro-channel has a small cross-sectional area but the collective surface area of all channels provides extensive heat transfer. The segmentation into numerous small channels reduces the pressure required in each individual channel while maintaining high total heat dissipation capacity
Solution Approach 2:
The system transitions from single large-channel cooling to multi-dimensional micro-channel networks. The manifolds are positioned radially inboard of the outer peripheral surface, creating a multi-level architecture where coolan( flows through axial manifolds, then distributes into radial micro-channels extending through the lamination thickness, utilizing multiple spatial dimensions to achieve high surface area with low pressure drop
3Loss of energy
If micro-channels are used to increase surface area, then heat dissipation efficiency improves, but the manufacturing complexity increases
Solution Approach 1:
The cooling apertures are strategically positioned in specific local regions of the laminations rather than uniformly distributed. The manifolds are positioned radially inboard of the outer peripheral surface, and micro-channels are created at specific angular positions and axial locations where heat generation is highest, optimizing cooling effectiveness while minimizing the number of apertures required and simplifying fabrication
Solution Approach 2:
The manufacturing process is segmented into discrete steps: forming cooling apertures in individual laminations, stacking laminations with alternating aperture orientations, and assembling the heat exchanger components. This segmentation allows each lamination to be manufactured independently with standard techniques, then combined to create the complete micro-channel network, reducing overall manufacturing complexity
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 a highly efficient heat exchanger that effectively dissipates heat from the radially outward regions of the lamination stack, mitigating uneven cooling and hotspot issues, and reducing motor losses by lowering the power needed for coolant circulation.
Implementation Method 1
routing fluid along internal surfaces of a stator core
Implementation Method 2
heat dissipation by routing fluid through the micro-channel heat exchanger
Implementation Method 3
the electromagnetic relationships between the stator and the rotor produce currents that, in turn, generate heat due to resistive heating
Implementation Method 4
AC magnetic fields lead to losses in the magnetic steel supporting the windings and conductors in the stator and rotor, respectively
Implementation Method 5
losses in the magnetic steel supporting the windings and conductors
Data Source
AI summary
An electric machine has a stator that comprises a plurality of laminations with an outer periphery, and each of the laminations has teeth about a central opening such that when the laminations are stacked side-by side to form the stator core, the plurality of teeth of adjacent laminations cooperate to form slots disposed circumferentially about the central opening that are configured to receive a plurality of stator windings. Each of the laminations has a plurality of cooling apertures angularly spaced about the central opening. The cooling apertures of adjacent laminations cooperate to form cooling manifolds that extend along a length of the stator core. A portion of the laminations has their cooling apertures offset from other laminations in the stack in a manner to create a plurality of flow path transverse to the manifolds and angularly between laminations and adjacent manifolds.