Stator Heat Exchanger Layout for High-Power Electric Machine Cooling
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Solution Overview
Problem
Current cooling technologies for electric machines, such as motors and generators, face inefficiencies in terms of performance and cooling, particularly due to thermal management challenges related to temperature-sensitive materials and high power densities.
Innovation Solution
The implementation of a stator package with a heat exchanger positioned between stator core stacks, where the heat exchanger has a unique design with circumferential and undulating coolant flow paths, allowing for effective cooling of both stator coils and stator cores without degrading the slot fill factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cooling schemes (radial air ducts, single radial duct, fin-shaped structures) are used, then cooling is provided to the electric machine, but cooling efficiency is insufficient and performance is degraded
Solution Approach 1:
The stator core is divided into multiple stacked laminations with cooling channels formed between adjacent stacks. This segmentation allows coolant to flow through multiple discrete paths, increasing the total cooling surface area and improving heat dissipation efficiency compared to conventional single-duct designs.
Solution Approach 2:
Cooling channels are strategically positioned in specific regions of the stator core where heat generation is highest. The channel configuration varies by location to optimize cooling where needed most, rather than using a uniform cooling approach throughout the entire stator structure.
2Power
If thermal management technology is enhanced to manage temperature-sensitive materials, then power and torque densities can be improved, but device complexity increases
Solution Approach 1:
The structural support function of the stator core laminations is merged with the thermal management function by incorporating cooling channels directly into the lamination structure. This integration eliminates the need for separate cooling components, reducing overall system complexity while enabling effective thermal management for high power density applications.
Solution Approach 2:
The stator core structure serves multiple functions simultaneously: providing mechanical support for the windings, establishing magnetic flux paths, and acting as a heat dissipation system through integrated cooling channels. This multi-functionality reduces the need for additional dedicated cooling components.
3Loss of energy
If high winding temperatures are allowed to improve conductor conductivity, then power loss increases, but if cooling is intensified, then device complexity increases
Solution Approach 1:
Heat is extracted directly from the stator core at its source through the integrated cooling channels, preventing heat accumulation that would otherwise increase winding temperatures and copper losses. This direct heat extraction approach is more efficient than conventional methods and does not require additional complex cooling components.
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 enhances the cooling efficiency of electric machines, achieving effective thermal management and maintaining high power densities without slot fill factor degradation, thereby improving the overall performance and reliability of electric machines.
Implementation Method 1
each of the stator coils is arranged to extend through a respective one of the first stator core slots and a respective one of the first heat exchanger slots... such that the coolant passes in proximity to and cools one or more of the stator coils and also cools the first stator core portion
Implementation Method 2
coolant entering the first heat exchanger via the inlet both flows in a first direction circumferentially around at least a first portion of the heat exchanger from the inlet to the outlet, and also flows in an undulating manner both radially inwardly and radially outwardly
Data Source
AI summary
Stator packages and electric machines, and methods for cooling same, are disclosed herein. In an example embodiment, an electric machine includes a rotor, and a stator package having one or more stator coils, stator core portions, and a heat exchanger. The stator core portions and heat exchanger are arranged successively along a central axis, with the heat exchanger being positioned between the stator core portions. Each of the stator coils is arranged to extend along/within the stator core portions and heat exchanger. The heat exchanger includes walls forming passageways configured so that coolant entering the heat exchanger via an inlet both flows circumferentially from the inlet to an outlet, and additionally flows in an undulating manner both radially inwardly and outwardly substantially in between outer and inner wall surfaces of the heat exchanger, such that the coolant cools the one or more stator coils and the stator core portions.