Inductive Coil with Permeable Plating for Eddy Current Mitigation
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Solution Overview
Problem
Portable electronic devices face inefficiencies in inductive charging due to the proximity effect, where adjacent conductors in coils experience increased resistance from induced eddy currents, limiting power transfer efficiency in compact form factors.
Innovation Solution
Incorporating a magnetically permeable material plated on the surface of the conductive core in a pattern, such as a spiral or disjoint design, to mitigate eddy currents while maintaining a nominal distance between wire portions, thereby reducing resistance and enhancing inductive transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a compact coil design is used in portable electronic devices, then the device form factor is reduced, but the inductive charging efficiency decreases due to the proximity effect and eddy currents
Solution Approach 1:
The patent applies local quality by plating magnetically permeable material on specific portions of the wire surface in a pattern rather than uniformly. This localized treatment targets areas where eddy currents are most problematic while maintaining the compact coil structure, thus improving inductive charging efficiency without increasing device volume.
Solution Approach 2:
The patent uses composite materials by combining a conductive core wire with magnetically permeable material plated on its surface. This composite structure creates a wire that simultaneously maintains electrical conductivity for current flow while the magnetically permeable coating mitigates eddy currents and proximity effects, resolving the efficiency loss in compact designs.
2Power
If wire portions are placed closer together to increase power transfer, then inductive charging efficiency improves, but eddy currents increase due to the proximity effect
Solution Approach 1:
The patent converts the harmful eddy currents into a beneficial effect by using magnetically permeable material that guides and controls the magnetic field. The plated material transforms the problematic proximity effect into improved magnetic coupling between adjacent wire portions, allowing closer spacing while maintaining or improving power transfer efficiency.
Solution Approach 2:
The patent changes the physical parameters of the wire by adding magnetically permeable material with specific magnetic properties (high permeability, controlled conductivity). This parameter change alters how the wire interacts with magnetic fields, reducing eddy current losses while enabling closer wire spacing for improved power transfer.
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 flattens the current distribution across the coil, reducing resistance and increasing the efficiency (Q factor) of inductive power transfer, allowing for effective charging in constrained spaces without significant increases in coil spacing.
Implementation Method 1
The magnetically permeable material is capable of limiting an eddy current induced by a magnetic field from an adjacent portion of the wire
Implementation Method 2
The conductive core is surrounded by an insulating layer that electrically isolates the conductive core and portions of the length of wire include a magnetically permeable material
Implementation Method 3
a battery and an inductive charging unit coupled to the battery. The inductive charging unit is capable of providing power to the battery and includes an inductive coil that is formed of a wire arranged in a spiral pattern having one end electrically coupled to a ground and a second end electrically coupled to the battery. The wire includes a conductive core capable of carrying an electrical current that is induced by an interaction with an external magnetic field
Data Source
AI summary
An inductive coil capable of providing power to the battery is described. The inductive coil is formed of a length of a wire having a conductive core capable of carrying an electrical current. The conductive core is surrounded by an insulating layer that electrically isolates the conductive core. Portions of the length of wire include a magnetically permeable material that is plated on an exposed surface of the conductive core.