Conductive Layering in Inductive Energy Transfer to Limit Eddy Heating

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Solution Overview

Problem

Rotating energy transfer devices in electrically excited synchronous machines experience inefficiencies and heat generation due to eddy currents in electrically conductive materials, leading to losses and reduced mechanical stability, especially in contactless inductive energy transfer systems.

Innovation Solution

Applying an additional electrically conductive material layer with higher conductivity than the existing materials on active parts of the energy transfer device, such as copper, silver, or graphene, to minimize eddy current penetration and heat generation by utilizing the skin effect, thereby reducing energy losses and increasing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If contactless inductive energy transfer is used, then mechanical stability is improved, but heat generation due to eddy currents increases

Engineering Contradiction:

Improvemechanical stabilityVSAvoidheat generation

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The patent applies the skin effect (a harmful phenomenon at high frequencies) beneficially by using highly conductive material layers to confine eddy currents to the surface, preventing heat generation in the bulk material and converting what would be a loss mechanism into a protective shielding effect

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the electrical conductivity parameter of the active parts by applying highly conductive material layers (silver, copper, graphene) with conductivity significantly higher than the base material, thereby altering the eddy current distribution and reducing heat generation in the bulk material

Inventive Principle:

Principle #35Parameter changes

2Temperature

If cooling measures are implemented to reduce heat generation, then temperature is reduced, but device complexity increases

Engineering Contradiction:

ImprovetemperatureVSAvoiddevice complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The highly conductive material layers automatically perform the heat reduction function through their inherent electrical properties, confining eddy currents to the surface and eliminating the need for external cooling systems or active temperature control mechanisms

Inventive Principle:

Principle #25Self-service

3Power

If energy sources are placed on the rotor, then power output is increased, but heat generation and reliability problems occur

Engineering Contradiction:

Improvepower outputVSAvoidreliability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The skin effect, which would normally cause harmful eddy current losses, is converted into a beneficial shielding mechanism that protects the rotor from heat generation, enabling the placement of energy sources on the rotor without reliability concerns

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 additional conductive layer effectively reduces heat generation and increases the efficiency of energy transfer by containing eddy currents within the layer, minimizing losses and enhancing the overall performance of the energy transfer device, particularly in high-frequency applications.

Implementation Method 1

undesired heat development due to eddy currents that are induced in the surrounding electrically conductive materials of the energy transfer device

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Implementation Method 2

minimize eddy current penetration and heat generation by utilizing the skin effect

Methodology Applied

Scientific EffectSkin effect: Skin Effect

Data Source

PatentUS11870307B2Method for increasing the efficiency of an energy transfer device, energy transfer device, and use of an electrically conductive material

Publication Date: 2024.01.09 UNIVERSITAT STUTTGART

AI summary

The present invention relates to a method for increasing the efficiency of an energy transfer device (100) with which electrical energy is converted contactlessly into electrical energy with the aid of a magnetic field in order to electrically excite a rotor of an electrical machine, comprising the step of:arranging an additional electrically conductive material layer (13) on at least one active part (12, 19, 35, 45) of the energy transfer device (100), wherein an active part of the energy transfer device (100) is a part of the energy transfer device (100) which is at least partially exposed to the magnetic field used for energy transfer, and wherein the electrical conductivity of the additional material layer (13) is greater than the electrical conductivity of the at least one active part (12, 19, 35, 45).Moreover, the invention relates to an energy transfer device (100) and to a use of an electrically conductive material.