Segmented Stator Core With Internal Slot Cooling for High Power Density

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Solution Overview

Problem

Existing stator core designs fail to effectively cool the internal coils, leading to increased temperature and risk of insulation damage, while conventional temperature sensors only monitor the end coils, failing to reflect internal temperature changes.

Innovation Solution

A segmented stator core design with internal cooling fluid pathways that directly cool the coils within the slots, enhancing cooling efficiency by allowing cooling fluid to flow from the outer diameter into the slots and directly contact the internal coils.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the size of vehicle motors is reduced to increase power per unit volume, then power density is improved, but copper loss increases and coil temperature rises causing insulation damage

Engineering Contradiction:
Improvepower per unit volumeVSAvoidcoil temperature
Core Design Contradiction:
PowerVSTemperature

Solution Approach 1:

The stator core is divided into multiple segments (first stator core, second stator core, third stator core) arranged in sequence. The second stator core includes a through-hole that forms a cooling passage, allowing cooling fluid to flow through the interior of the stator core and directly cool the coil windings, thereby reducing coil temperature while maintaining high power density

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A cooling fluid passage is introduced through the second stator core, allowing cooling fluid to flow through the interior of the stator core. The cooling fluid directly contacts the coil windings through the through-hole, providing efficient hydraulic cooling to remove heat generated by copper loss and maintain acceptable operating temperatures

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Temperature

If a cooling flow path is introduced inside the stator core to cool internal coils, then cooling performance is improved, but device complexity increases

Engineering Contradiction:
Improveinternal coil temperatureVSAvoidstator core structure
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The stator core is divided into three separate segments, with the cooling function integrated into the second stator core through the through-hole. This segmentation allows the cooling passage to be formed as part of the core structure itself rather than adding separate cooling components, reducing overall device complexity while achieving internal coil cooling

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The second stator core serves dual functions: it provides the magnetic core structure necessary for motor operation and simultaneously houses the cooling passage through its through-hole. This multi-functionality eliminates the need for separate cooling components, reducing device complexity while achieving effective internal coil cooling

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 design effectively reduces coil temperature, minimizing the risk of damage and enabling higher current density, thus increasing power density or reducing motor size without additional components, while lowering material and manufacturing costs.

Implementation Method 1

a cooling flow path extending to receive cooling fluid from an outside and deliver the cooling fluid to an inside of the second slot

Methodology Applied
Scientific EffectHeat transfer: Convection

Data Source

PatentEP4521604B1Segmented stator core
Publication Date: 2026.04.08 HYUNDAI MOBIS CO LTD
  • EP4521604B1 patent drawingFigure 1
  • EP4521604B1 patent drawingFigure 2
  • EP4521604B1 patent drawingFigure 3

AI summary

The present disclosure relates to a stator core applied to an electric motor, and more particularly, to a stator core design having improved cooling performance. In the segmented stator core of the present disclosure, since the coil inside the slot having a temperature higher than that of the end coil is cooled, the risk of damaging the insulating portion may be reduced, and since both the end coil and the coil inside the slot may be cooled, a load is small even if a high current is applied, and thus, the power may be increased in the same motor size or the motor size based on the same power may be reduced.