Toroidal Inductor Cooling Using Shape-Matched Winding Geometry

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Solution Overview

Problem

Toroidal inductive devices face challenges in cooling, particularly in attaching a cooling element due to the risk of electrical conductivity and leakage with conductive liquids, and the need for measures against evaporation with non-conductive liquids, which affects heat dissipation efficiency.

Innovation Solution

A toroidal inductive device design featuring a cylindrical cavity with a rectangular cross-section for the electric conductor and a circular cross-section for the cavity, filled with electrically insulating material to enhance heat transfer, and optionally including cooling fins or ducts for improved cooling, ensuring equal distances from the conductor to the cavity walls for efficient heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a cooling element is attached to the toroidal inductive device surface, then heat dissipation efficiency is improved, but the risk of electrical leakage and insulation damage increases when using conductive cooling liquids

Engineering Contradiction:

Improveheat dissipation efficiencyVSAvoidinsulation reliability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent introduces an intermediary substance (cooling liquid or gas) that transfers heat from the toroidal inductive device to the cooling element without direct electrical contact. The cooling liquid flows through channels in the cooling element, acting as a thermal mediator while the insulating barrier prevents electrical leakage, thus resolving the contradiction between heat dissipation efficiency and insulation reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cooling element is segmented into distinct functional zones: a thermal contact surface that touches the toroidal inductive device for heat transfer, internal channels for cooling liquid flow, and an insulating barrier layer. This segmentation allows optimized heat dissipation while maintaining electrical isolation, addressing both heat dissipation efficiency and insulation reliability requirements.

Inventive Principle:

Principle #1Segmentation

2Reliability

If transformer oil or non-conductive liquid is used for cooling, then insulation reliability is improved, but measures against leakage and evaporation are required increasing device complexity

Engineering Contradiction:

Improveinsulation reliabilityVSAvoidleakage prevention measures

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs a flexible insulating barrier film or shell that encloses the cooling liquid channels within the cooling element. This thin film structure provides effective leakage prevention while maintaining the simplicity of the overall device design, allowing the use of non-conductive cooling liquids without requiring complex external containment systems.

Inventive Principle:

Principle #30Flexible shells and thin films

3Temperature

If the cooling element is placed in direct contact with the toroidal inductive device, then heat transfer efficiency is improved, but the manufacturing precision requirements increase due to surface matching challenges

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidsurface matching precision

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The cooling element features a localized high-thermal-conductivity contact region that interfaces with the toroidal inductive device surface, while other regions use lower-conductivity materials. This local quality differentiation concentrates the manufacturing precision requirements to only the critical thermal contact area, reducing overall manufacturing complexity while maintaining high heat transfer efficiency at the interface.

Inventive Principle:

Principle #3Local quality

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 improves heat transfer and reduces the risk of electrical issues by matching the conductor and cavity shapes, providing effective cooling while minimizing leakage risks and enhancing thermal conductivity.

Implementation Method 1

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

filled with electrically insulating material to enhance heat transfer

Methodology Applied

Scientific EffectElectrical insulation: Dielectric

Data Source

PatentEP3330983B1An inductive device

Publication Date: 2023.10.04 DANFOSS EDITRON OY

Figure 1a~1b
Figure 1c~2

AI summary

An inductive device comprises a toroidal core (101) and at least one electric conductor (102) wound around the toroidal core and constituting at least one winding. The inductive device comprises a cooling element (104) constituting a cylindrical cavity that contains the toroidal core and the electric conductor so that the axial direction of the toroidal core is parallel with the axial direction of the cylindrical cavity. The shape of the cylindrical cavity and the cross-section of the electric conductor are adapted to match each other so as to improve heat transfer from the electric conductor to the wall of the cylindrical cavity. The cylindrical cavity can have for example a circular base and the electric conductor can have for example a rectangular cross-section that matches the shape of the wall of the cylindrical cavity better than a round electric conductor.