Frequency-Selective Patch Array for Wireless Power Shielding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wireless power transfer systems face challenges in containing electromagnetic fields within the charging area, leading to unwanted energy transmission and interference with other electronics, which violates regulatory standards such as EMC and SAR.
Innovation Solution
A frequency-selective patch array is disposed below the transmit coil to shield electromagnetic radiation, appearing transparent at the operating frequency while acting as a solid conductor at other frequencies, thereby maintaining high transmission efficiency while suppressing unwanted emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a planar conductive sheet or passive metal loop is disposed below the transmit coil to reduce electromagnetic radiation, then electromagnetic emissions are suppressed, but transmission efficiency significantly decreases
Solution Approach 1:
The patent divides the continuous conductive sheet into discrete conductive patches arranged in an array. This segmentation allows the shield to suppress electromagnetic radiation through the gaps between patches while maintaining transmission efficiency by not forming a complete conductive barrier that would block the operating frequency signals.
Solution Approach 2:
The patent applies different properties to different parts of the shielding structure. The conductive patches provide local electromagnetic shielding at specific locations, while the gaps between patches allow signal transmission. This localized approach enables selective suppression of harmful emissions without uniformly blocking the power transfer path.
2Object-generated harmful factors
If ferrite sheets are disposed below the transmit coil to control magnetic flux path and reduce electromagnetic radiation, then electromagnetic interference is suppressed, but the size and cost increase due to material requirements
Solution Approach 1:
The patent changes the structural parameters of the shield from a continuous material (ferrite sheet) to a discrete array structure. This parameter change allows achieving similar electromagnetic interference suppression through geometric arrangement rather than material properties, reducing size and cost constraints.
Solution Approach 2:
The patent uses a composite structure combining conductive patches with non-conductive substrate material. This composite approach replaces the need for specialized ferrite materials with a simpler combination of conductive and insulating materials, reducing cost and manufacturing complexity.
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 reduces unintentional radiative emissions, improving compliance with electromagnetic compatibility and specific absorption ratio standards while maintaining efficient wireless power transfer.
Implementation Method 1
a patch array disposed in parallel with the transmit coil to reduce a strength of the magnetic field at frequencies outside of the operating frequency
Implementation Method 2
the transmit coil creates an alternating electromagnetic field and the receive coil takes power from the electromagnetic field
Data Source
AI summary
Techniques for focusing an energy radiated by a wireless power transmitting unit are described. An example power transmitting unit includes a transmit coil configured to generate a magnetic field to wirelessly power a device within an active wireless charging area. The power transmitting unit also includes a power generating circuitry to deliver a current to the transmit coil to generate the magnetic field. The power transmitting unit also includes a patch array disposed in parallel with the transmit coil to reduce a strength of the magnetic field at frequencies outside of the operating frequency during operation of the power transmitting unit.