Shielded Inductor Coil Structure for Lower Wireless Charging Loss
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Solution Overview
Problem
Conventional inductors in wireless chargers experience significant proximity effects due to external magnetic fields, leading to increased resistance and power loss, particularly at operating frequencies like 100 kHz to 400 KHz.
Innovation Solution
A shielding layer made of a conductive and magnetic material, such as nickel, is applied to encapsulate the coil to shield it from external magnetic fields, and graphene sheets are placed on the bottom surface to reduce eddy currents, while the electrodes are configured for easy electrical connection with an external circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional inductor is used in a wireless charger, then the device structure is simple, but the proximity effect caused by external magnetic fields increases resistance and power loss
Solution Approach 1:
The patent applies composite materials by combining copper (high electrical conductivity) with nickel (magnetic shielding properties) to form a bi-metallic structure. The copper core provides low electrical resistance while the nickel coating provides magnetic shielding, reducing the proximity effect and power loss simultaneously.
Solution Approach 2:
The patent changes the physical parameters of the inductor by controlling the thickness of the nickel coating (1-10 micrometers) and the diameter of the copper wire (50-200 micrometers). These parameter optimizations balance the magnetic shielding effect with electrical conductivity to minimize power loss.
2Reliability
If a shielding layer is added to encapsulate the coil, then the alternating current resistance decreases, but the manufacturing complexity increases
Solution Approach 1:
The patent replaces traditional mechanical winding and insulation processes with electrochemical deposition (electroplating) to apply the nickel shielding layer. This substitution simplifies manufacturing by enabling continuous coating during the wire drawing process, reducing labor and assembly steps.
Solution Approach 2:
The magnetic shielding layer is applied in advance during the wire manufacturing process, before the coil is wound and assembled into the final inductor. This preliminary action integrates the shielding function into the base material production, eliminating separate shielding installation steps.
3Power
If the coil is wound with thicker metal wire, then the current carrying capacity increases, but the proximity effect from external magnetic fields worsens
Solution Approach 1:
The patent uses composite materials by combining copper (high electrical conductivity) with nickel (magnetic shielding properties) to form a bi-metallic structure. The copper core provides low electrical resistance while the nickel coating provides magnetic shielding, reducing the proximity effect and power loss simultaneously.
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 solution effectively lowers the alternating current resistance (ACR) of the coil, enhances the Q value of the wireless charger, and reduces power loss, thereby improving the efficiency of the inductor in wireless charging applications.
Implementation Method 1
a shielding layer comprising a first conductive and magnetic material to encapsulate each of the plurality of winding turns of the coil
Implementation Method 2
Conventional inductors cannot prevent the proximity effect caused by an external magnetic field
Implementation Method 3
a plurality of separated graphene sheets are disposed over the bottom surface of the encapsulating layer
Data Source
AI summary
A shielding layer that is made of conductive and magnetic material is used to encapsulate the bare metal wire of a coil of an inductor to shield the coil from the external magnetic field and make the resistance and the power loss of the inductor lower.