Stator Dual-Path Coolant Flow for Higher Continuous Power Density

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Solution Overview

Problem

Existing electric machines lack effective cooling mechanisms to enhance stator performance and increase continuous power density.

Innovation Solution

The electric machine employs dual coolant flow paths - direct cooling through recesses accommodating stator windings and indirect cooling through channels spaced apart from the recesses, with a mechanism to adjust coolant flow based on operating points, using an orifice ring or valves to control coolant distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If direct cooling through recesses is used, then cooling efficiency is improved, but device complexity increases due to dual cooling paths

Engineering Contradiction:

Improvestator cooling efficiencyVSAvoidcooling system complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The cooling system is segmented into two distinct cooling paths: direct cooling through recesses for high-load conditions and indirect cooling through channels for low-load conditions. This segmentation allows each path to be optimized for specific operating conditions, improving overall cooling efficiency while managing complexity through conditional activation

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cooling system dynamically switches between direct and indirect cooling paths based on operating conditions. A control mechanism adjusts the coolant flow distribution between the two paths according to the operating point, enabling the system to adapt to varying load requirements and optimize cooling efficiency across different operating scenarios

Inventive Principle:

Principle #15Dynamics

2Power

If dual coolant flow paths are implemented, then continuous power density is increased, but manufacturing complexity increases

Engineering Contradiction:

Improvecontinuous power densityVSAvoidstator manufacturing complexity

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The direct cooling recesses and indirect cooling channels are merged into a unified stator structure, sharing common walls and integration points. This merging approach allows both cooling paths to be manufactured as an integrated component, reducing the number of separate parts and assembly steps while achieving enhanced continuous power density

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Different regions of the stator are assigned different cooling functions: recesses are positioned for direct coolant contact with windings in high-heat-generation areas, while channels are positioned for indirect cooling in adjacent regions. This local differentiation optimizes cooling where needed most while simplifying manufacturing by avoiding uniform complexity throughout the entire stator structure

Inventive Principle:

Principle #3Local quality

3Temperature

If coolant flow is optimized for high loads, then cooling efficiency is improved, but energy consumption increases at low loads

Engineering Contradiction:

Improvecoolant cooling efficiencyVSAvoidenergy consumption at low loads

Core Design Contradiction:

TemperatureVSUse of energy by moving object

Solution Approach 1:

The system applies partial cooling action through the indirect cooling path at low loads, using only the necessary coolant flow required for the reduced thermal load. This partial action approach avoids the excessive energy consumption that would result from maintaining full direct cooling flow rates during low-load operation, while still providing adequate cooling through the indirect path

Inventive Principle:

Principle #16Partial or excessive action

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 approach provides efficient cooling, especially at high loads, increasing continuous power density and reducing energy consumption at lower loads by optimizing coolant flow.

Implementation Method 1

coolant can be conducted only through the recesses (17) which accommodate the stator windings (18)

Methodology Applied

Scientific EffectDirect cooling: Convection

Implementation Method 2

coolant can be conducted at least through the channels (23)

Methodology Applied

Scientific EffectIndirect cooling: Conduction (thermal)

Data Source

PatentUS12407223B2Electric machine and method for operating said machine

Publication Date: 2025.09.02 DR ING H C F PORSCHE AG

AI summary

An electric machine, including a rotor having a rotor shaft and a rotor laminated core, a stator having a stator laminated core with recesses and stator windings disposed in the recesses of the stator laminated core, wherein coolant can flow through the recesses such that the stator windings can be directly cooled by the coolant, wherein channels are configured in the stator laminated core at a distance to the recesses such that the stator windings can be indirectly cooled by the coolant flowing through the channels, and a device via which a flow of coolant through the recesses and through the channels can be set depending on an operating point of the electric machine such that, at first operating points, the coolant can be conducted only through the recesses and, at second operating points, the coolant can be conducted at least through the channels.