Magnetic Core With Integrated Liquid Cooling for Compact Power Magnetics

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Solution Overview

Problem

Magnetic components in power converters face challenges in heat extraction due to reduced surface area and poor thermal conductivity, leading to increased loss density and temperature gradients, which are exacerbated by manufacturing inaccuracies and the need for thermal interface materials, limiting the efficiency and compactness of high-power density designs.

Innovation Solution

A magnetic core with an integrated liquid cooling channel is created by inserting a soluble material into a mold, followed by a mix of magnetic powder, binder, and additives, which is pressed and cured, then dissolved to reveal the cooling channel, allowing for enhanced heat transfer and electrical functionality, particularly when combined with printed circuit boards for windings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the switching frequency is increased to reduce magnetic component volume, then the power density increases, but the loss density increases and heat extraction becomes more difficult

Engineering Contradiction:
Improvemagnetic component volumeVSAvoidloss density
Core Design Contradiction:
Volume of moving objectVSLoss of energy

Solution Approach 1:

The patent transitions from conventional external cooling to internal cooling by embedding liquid cooling channels within the magnetic core structure. This dimensional integration allows heat extraction from the interior of the core, effectively managing heat density without increasing external volume, thus resolving the contradiction between compact size and heat dissipation capability

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The cooling channels are merged directly into the magnetic core structure during manufacturing, combining the magnetic functionality and thermal management functionality into a single integrated component. This eliminates the need for separate heatsinks and thermal interface materials, reducing overall volume while maintaining effective heat extraction

Inventive Principle:
Principle #5Merging (Combining)

2Volume of moving object

If the surface area is reduced to decrease component volume, then the compactness improves, but the heat extraction capability deteriorates

Engineering Contradiction:
Improvecomponent volumeVSAvoidtemperature gradient
Core Design Contradiction:
Volume of moving objectVSTemperature

Solution Approach 1:

Instead of relying solely on external surface area for heat extraction, the patent creates internal cooling pathways that extend into the core volume. This allows heat to be extracted from three-dimensional space within the core rather than only from the two-dimensional external surface, maintaining compact volume while improving heat extraction capability

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent employs liquid cooling through embedded channels, using fluid convection to transfer heat from the magnetic core interior to the coolant. This hydraulic cooling system provides superior heat extraction compared to conventional air cooling or heatsink approaches, effectively managing temperature gradients in compact designs

Inventive Principle:
Principle #29Pneumatics and hydraulics

3Manufacturing precision

If machining or grounding is performed to improve dimensional accuracy for heatsink assembly, then the thermal contact improves, but the manufacturing cost increases substantially

Engineering Contradiction:
Improvedimensional accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The cooling channels are integrated into the magnetic core during the core manufacturing process itself, rather than being added as a separate assembly step. This merging of functions eliminates the need for subsequent machining or grounding operations to achieve thermal contact, as the cooling structure is already precisely positioned within the core

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The cooling channel structure is prepared in advance during core manufacturing, with precise dimensional accuracy built into the core fabrication process. This preliminary creation of the cooling structure eliminates the need for post-manufacturing machining or grounding operations, significantly reducing manufacturing costs while maintaining precision

Inventive Principle:
Principle #10Preliminary action

4Reliability

If thermal interface material is used to fill voids between surfaces, then the thermal contact improves, but the thermal resistance increases substantially

Engineering Contradiction:
Improvethermal contactVSAvoidthermal resistance
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The cooling channels are manufactured as an integral part of the magnetic core structure, eliminating the interface between separate components. This direct integration removes the need for thermal interface materials that would introduce thermal resistance, achieving superior thermal contact through structural unity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent eliminates the thermal interface material layer by directly integrating the cooling channels into the core structure. By taking out the intermediate thermal interface material and creating a direct fluid-to-core heat transfer path, thermal resistance is minimized while maintaining reliable thermal contact

Inventive Principle:
Principle #2Taking out (Extraction)

5Temperature

If drilling is performed to insert cooling channels after manufacturing, then the heat extraction capability improves, but the tool wear increases and channel shape is restricted

Engineering Contradiction:
Improveheat extraction capabilityVSAvoidtool wear
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The cooling channels are created during the core manufacturing process itself, before the core is completed and hardened. This preliminary formation of channels using flexible molds allows for complex three-dimensional channel geometries without requiring subsequent drilling operations, eliminating tool wear issues while maintaining excellent heat extraction capability

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the manufacturing parameter approach from post-manufacturing drilling to in-process channel formation using soluble inserts. This parameter change allows the channel shape to be defined by the insert geometry rather than drilling constraints, enabling complex curved and three-dimensional channel configurations that maximize heat extraction while avoiding tool wear

Inventive Principle:
Principle #35Parameter changes

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 increases heat transfer efficiency with minimal volume increase, enabling the realization of compact transformers and inductors while reducing thermal resistance and maximizing power density.

Implementation Method 1

injecting a solvent in the inner channel in order to dissolve the soluble material

Methodology Applied
Scientific EffectDissolution: Solvation

Data Source

PatentEP3940729B1A magnetic core with an integrated liquid cooling channel and a method to make the same
Publication Date: 2023.10.25 MITSUBISHI ELECTRIC R&D CENTRE EUROPE BV
  • EP3940729B1 patent drawingFigure 1~2
  • EP3940729B1 patent drawingFigure 3
  • EP3940729B1 patent drawingFigure 4~5

AI summary

The present invention concerns a magnetic core with an integrated liquid cooling channel and a method to make the same. The method comprises the steps of: - inserting a part of a soluble material that have a shape that corresponds to a liquid cooling channel in a mold, the part of the soluble material having an inner channel, - pouring a mix of magnetic powder, binder and additives in the mold. - pressing the mix of magnetic powder, binder and additives, - curing the pressed mix of magnetic powder, binder and additives, - injecting a solvent in the inner channel in order to dissolve the soluble material.