Segmented Magnetic Sheet for Wireless Charging Eddy Current Reduction
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Solution Overview
Problem
Magnetic sheets used in wireless charging systems experience significant magnetic losses due to eddy currents, which reduce the efficiency of wireless charging, especially in the frequency band used for portable devices.
Innovation Solution
A magnetic sheet with a metal sheet layer composed of divided segments and an insulating material filled between the segments is used to form a magnetic path, reducing eddy current losses by artificially dividing the metal sheet layer and using alloy ribbon layers made of materials like sendust, permalloy, and Fe—Si—B alloys, with insulating materials such as chlorinated polyethylene resins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal magnetic sheet is used to form a magnetic path, then high saturation flux density is achieved, but magnetic loss due to eddy currents increases significantly
Solution Approach 1:
The metal magnetic sheet is divided into a plurality of segments with insulating material filled between them. This segmentation interrupts the eddy current paths while maintaining the magnetic path continuity, thereby reducing magnetic loss due to eddy currents while preserving high saturation flux density.
2Length of moving object
If the magnetic sheet is made thinner to accommodate portable devices, then device slimming is achieved, but magnetic characteristics and loss reduction become more difficult
Solution Approach 1:
The magnetic sheet uses a composite structure combining metal magnetic powder (for high saturation flux density) with polymer resin (for insulation and structural integrity). This composite approach enables thin design while maintaining effective eddy current suppression and magnetic characteristics.
3Loss of energy
If ferrite sheet is used as magnetic material, then eddy current loss is reduced, but saturation flux density and magnetic characteristics are insufficient
Solution Approach 1:
The invention uses metal magnetic powder (such as sendust, permalloy, Fe-Si-B, etc.) combined with polymer resin to create a metal-composite magnetic sheet. This composite material achieves both high saturation flux density from the metal powder and effective eddy current suppression through the insulating resin matrix, overcoming the limitations of pure ferrite sheets.
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 configuration reduces magnetic losses and increases wireless charging efficiency by forming a sufficient magnetic path while maintaining high saturation flux density, allowing for thinner designs suitable for portable devices.
Implementation Method 1
an eddy current is generated in the metal by a magnetic field generated in the power receiving coil, resulting in a reduction in efficiency due to heat and loss of magnetic field in the metal object
Implementation Method 2
a magnetic sheet is inserted between the power receiving coil and the metal object
Implementation Method 3
the magnetic sheet forms a magnetic path of a magnetic field generated around a coil
Implementation Method 4
an insulating material filled in a dividing space between the segments
Data Source
AI summary
The present invention relates to a magnetic sheet, a wireless charging sheet, and a method for manufacturing a magnetic sheet. According to an embodiment of the present invention, a magnetic sheet used in a wireless charging sheet, which includes a metal sheet layer consisting of a plurality of divided segments; and an insulating material filled in a dividing space between the segments and forms a magnetic path of a magnetic field generated around a coil, is provided. Further, a wireless charging sheet and a method for manufacturing a magnetic sheet are provided.