Segmented Electrical Machine Core for Liquid Cooling
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Solution Overview
Problem
Conventional liquid cooled electrical machines experience inefficiencies due to coolant infiltration into the gap between the rotor and stator, leading to increased windage losses and reduced efficiency, especially at high speeds.
Innovation Solution
A segmented core with radially outer and inner portions, featuring windings slots with high thermal conductivity insulators and a finned heat exchanger, allows for enhanced heat transfer and reduced windage losses by eliminating the need for coolant spray cooling, utilizing materials like cobalt-iron alloys and nanofoil layers for improved thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If coolant spray is applied to windings for cooling, then heat dissipation is improved, but coolant infiltrates the gap between rotor and stator causing increased windage losses
Solution Approach 1:
The core is divided into alternating segments of first material (with coolant passages) and second material (without coolant passages). This segmentation allows heat to be conducted through both material types while restricting coolant flow paths to prevent gap infiltration, thereby resolving the contradiction between effective cooling and minimizing windage losses.
Solution Approach 2:
Different segments of the core have different thermal and fluid flow properties. The first material segments provide coolant flow paths for heat removal, while the second material segments provide structural support and block coolant from entering the gap. This local differentiation enables simultaneous achievement of heat dissipation and windage loss reduction.
2Temperature
If conventional cooling systems are used, then heat is dissipated, but the system complexity increases due to coolant delivery mechanisms
Solution Approach 1:
The cooling function is merged into the core structure itself. The alternating segments of first and second materials form an integrated thermal management system where the core both supports the windings and provides coolant flow paths, eliminating the need for separate cooling mechanisms and reducing overall system complexity.
Solution Approach 2:
The core structure serves multiple functions: mechanical support for windings, magnetic flux path, and thermal management through integrated coolant passages. This multi-functionality reduces the need for additional dedicated cooling components, simplifying the overall system while maintaining effective heat dissipation.
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
The solution significantly reduces heat rejection requirements by up to 80% at high speeds, enhancing the efficiency and operational stability of electrical machines by minimizing windage losses and maintaining effective cooling without coolant infiltration.
Implementation Method 1
the first segments radially transfer heat from the windings to the heat exchanger at a greater rate than the second segments
Implementation Method 2
The heat exchanger can be in fluid communication with a coolant supply and a coolant return
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A core (100) for an electrical machine has a segmented body (102) with first segments (120) and second segments (130). The first segments (120) extend from a radially inner portion (106) of the segmented body to a radially outer portion (104) of the segmented body. The second segments (130) are axially stacked in alteration with the first layers along an axis of the segmented body (102). The first segments have thermal conductivity greater than thermal conductivity of the second segments for transferring heat from the radially outer portion of the segmented body to the radially inner portion of the segmented body.