Variable Thickness Ferrite Layer for Wireless Charging

Solution Overview

Problem

Wireless charging systems face inefficiencies due to magnetic field leakage into conductive surfaces, leading to non-uniform magnetic field strength and flux density across the coil assembly, which can reduce charging efficiency and require excessive ferrite material for uniform shielding.

Innovation Solution

A variable thickness magnetic layer is applied across the coil assembly, with thicker ferrite material in areas of high magnetic field strength and thinner material in areas of low strength, optimizing material usage while maintaining efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If uniform thickness ferrite material is used across the coil assembly, then magnetic field shielding is provided, but material cost and weight increase excessively

Engineering Contradiction:

Improvemagnetic field shieldingVSAvoidferrite material weight

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent applies different thicknesses of ferrite material at different locations on the coil assembly based on the local magnetic field strength. Thicker ferrite is applied where magnetic field strength is higher, and thinner ferrite where field strength is lower, optimizing material usage while maintaining shielding effectiveness.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the thickness parameter of the ferrite material across different regions of the coil assembly. By varying this physical parameter according to the magnetic field distribution, the system achieves effective shielding with reduced overall material quantity and weight.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If uniform thickness ferrite material is used across the coil assembly, then magnetic field shielding is provided, but material cost increases excessively

Engineering Contradiction:

Improvemagnetic field shieldingVSAvoidferrite material consumption

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent applies different thicknesses of ferrite material at different locations on the coil assembly based on the local magnetic field strength. Thicker ferrite is applied where magnetic field strength is higher, and thinner ferrite where field strength is lower, optimizing material usage while maintaining shielding effectiveness.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the thickness parameter of the ferrite material across different regions of the coil assembly. By varying this physical parameter according to the magnetic field distribution, the system achieves effective shielding with reduced overall material quantity and weight.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If thicker ferrite material is used in high field strength areas, then magnetic flux density uniformity is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvemagnetic flux density uniformityVSAvoidvariable thickness application

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent divides the coil assembly surface into multiple regions based on magnetic field strength characteristics. By segmenting the application area and applying appropriate ferrite thickness to each segment, the system achieves uniform magnetic flux density while managing manufacturing complexity through systematic regional classification.

Inventive Principle:

Principle #1Segmentation

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 reduces material costs and weight by at least 35% while maintaining system efficiency, ensuring a substantially uniform magnetic flux density across the region of interest, thus enhancing wireless charging efficiency.

Implementation Method 1

when energized, the coil generates an in-plane magnetic field component in a region of interest in air proximate and substantially parallel to the first major boundary surface

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

when energized, the coil generates a magnetic field inducing an in-plane magnetic flux density B in the magnetic layer in the region of interest that varies less than about 5% in the region of interest

Methodology Applied

Scientific EffectMagnetic flux density uniformization: Magnetic Field

Data Source

PatentUS20220375683A1Variable magnetic layer for wireless charging

Publication Date: 2022.11.24 3M INNOVATIVE PROPERTIES CO

AI summary

A magnetic film assembly includes a coil having a plurality of turns defining a first major boundary surface of the coil, such that when energized, the coil generates an in-plane magnetic field component in a region of interest in air proximate and substantially parallel to the first major boundary surface, the in-plane magnetic field component having a magnetic field strength H that varies between a maximum Hmax and about 10% of Hmax in the region of interest in air; and a magnetic layer disposed on the coil so as to include the region of interest, such that when energized, the coil generates a magnetic field inducing an in-plane magnetic flux density B in the magnetic layer in the region of interest that varies less than about 5% in the region of interest.