Magnetic Sheet Concentration Gradient Eddy Current Loss
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Solution Overview
Problem
Existing magnetic sheets used in near field communication and wireless power transfer face challenges in achieving high transfer efficiency due to limitations in magnetic permeability and thickness, leading to increased eddy current loss and reduced freedom in design.
Innovation Solution
A magnetic sheet with a bonding part that includes a concentration gradient of magnetic particles in the thickness direction, dispersed in multiple adhesive layers, to enhance magnetic permeability and bonding force while maintaining a thin structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a magnetic sheet is formed as a unitary body to reduce thickness, then thickness is reduced, but conductivity increases and eddy current loss increases exponentially
Solution Approach 1:
The magnetic sheet is divided into multiple stacked metallic ribbons instead of being formed as a unitary body. This segmentation reduces the continuous conductive path, thereby reducing eddy current loss while maintaining thin thickness for electromagnetic isolation and magnetic resonance functions.
Solution Approach 2:
The patent uses a composite structure of multiple metallic ribbons stacked with insulating adhesive films in between. This composite material approach combines the high magnetic permeability of metallic ribbons with the insulating properties of adhesive films, reducing eddy current loss while maintaining the desired magnetic properties and thin overall thickness.
2Loss of energy
If adhesive films are disposed between every two metallic ribbons to form a stacked structure, then magnetic flux loss is reduced, but total effective magnetic permeability is lowered due to magnetic flux loss in the adhesive film
Solution Approach 1:
The patent applies magnetic particles selectively in the bonding part rather than uniformly throughout the entire magnetic sheet. This local quality enhancement compensates for the magnetic flux loss in adhesive films at the bonding interface, maintaining effective magnetic permeability while still using the stacked structure to reduce eddy current loss.
Solution Approach 2:
The patent changes the magnetic properties of the bonding part by incorporating magnetic particles with specific concentration gradients. This parameter change compensates for the magnetic flux loss introduced by adhesive films, maintaining the overall effective magnetic permeability required for efficient wireless power transfer and NFC operations.
3Reliability
If the number of stacked layers is increased to compensate for effective magnetic permeability, then effective magnetic permeability is improved, but thickness is increased and design freedom is reduced
Solution Approach 1:
Instead of increasing the number of stacked layers throughout the entire structure, the patent enhances the magnetic properties locally at the bonding part where magnetic particles are concentrated. This approach improves effective magnetic permeability without proportionally increasing the overall thickness, preserving design freedom for NFC and wireless power transfer applications.
Solution Approach 2:
The patent uses a composite bonding part containing magnetic particles dispersed in adhesive material, combining the benefits of adhesive bonding with enhanced magnetic properties. This composite approach improves effective magnetic permeability more efficiently than simply adding more metallic ribbon layers, avoiding excessive thickness increase.
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 magnetic sheet achieves high transfer efficiency with sufficient bonding area and reduced eddy current loss, allowing for improved performance in both near field communication and wireless power transfer applications.
Implementation Method 1
magnetic permeability is good; however, there is a limitation related to thickness due to limitations related to high-temperature calcination and magnetic flux density
Implementation Method 2
conductivity increases, and as a result, eddy current loss increases exponentially
Implementation Method 3
energy is transferred in the form of a magnetic field having a particular frequency
Implementation Method 4
magnetic resonance method in terms of technology
Implementation Method 5
metallic ribbons and adhesive films having an insulation function may be alternately disposed in layers
Data Source
AI summary
A magnetic sheet according to an embodiment comprises: a first magnetic sheet part comprising a first surface; a second magnetic sheet part comprising a second surface facing the first surface; and an adhesion part disposed between the first surface and the second surface, wherein the adhesion part comprises a plurality of magnetic particles, and the plurality of magnetic particles may have a concentration gradient in the thickness direction of the adhesion part.