Patterned EMI Shield for Wireless Power Transfer Coils
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wireless power systems face challenges in reducing electric and electromagnetic interference (EMI) due to the production of unwanted frequencies during power transmission, which can affect the efficiency and reliability of energy transfer.
Innovation Solution
A patterned metallic EMI shield is positioned over the transmitting coil, capacitively coupling electromagnetic radiation to ground while allowing magnetic power to pass through, utilizing a substrate with wire traces and capacitors to minimize EMI without interfering with the magnetic field transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shield is placed over the transmitting coil to reduce EMI, then electromagnetic emissions are reduced, but magnetic power transfer may be blocked
Solution Approach 1:
The shield is segmented into a patterned metallic layer with discrete conductive traces separated by insulating spaces, rather than a continuous shield. This segmentation allows magnetic field lines to pass through the insulating regions while the conductive traces capture and ground electromagnetic radiation, resolving the contradiction between EMI reduction and magnetic power transfer.
Solution Approach 2:
The shield exhibits local quality differentiation where conductive traces are strategically positioned to intercept electromagnetic radiation in specific areas, while insulating regions allow magnetic field passage. The capacitive coupling at trace ends provides localized EMI filtering without creating continuous current paths that would block magnetic power transfer.
2Object-affected harmful factors
If a continuous metallic shield is used to block EMI, then electromagnetic radiation is reduced, but current flow paths are created that interfere with power transmission
Solution Approach 1:
The continuous metallic shield is segmented into discrete conductive traces separated by insulating material. This breaks up current flow paths that would otherwise be created by a continuous shield, preventing harmful induced currents while maintaining EMI filtering capability through the distributed trace structure.
Solution Approach 2:
The harmful continuous current path is extracted and replaced with discrete capacitive coupling points at the ends of conductive traces. This removes the mechanism for harmful current flow while preserving the ability to capacitively couple EMI to ground through the isolated trace endpoints.
3Object-affected harmful factors
If a patterned metallic layer with capacitive coupling is used, then EMI is filtered without blocking magnetic field, but device complexity increases
Solution Approach 1:
The patterned metallic layer serves multiple functions simultaneously: it provides EMI filtering through capacitive coupling to ground, allows magnetic field passage through insulating regions, and prevents harmful current flow through segmentation. This multi-functionality reduces overall system complexity despite the patterned structure.
Solution Approach 2:
The shield is implemented as a thin flexible patterned metallic layer on a substrate, which can be easily manufactured and integrated into the wireless power transmitter. This thin-film approach reduces structural complexity compared to bulk shielding materials while maintaining EMI filtering effectiveness.
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 electromagnetic emissions while maintaining the integrity of magnetic power transfer, minimizing conducted and radiated emissions and enhancing the overall efficiency of wireless power systems.
Implementation Method 1
a shield layer that, when positioned over a transmitting coil (106) of the wireless power transmitter, capacitively couples to the transmitting coil (106) to capture electromagnetic radiation
Implementation Method 2
capture electromagnetic radiation while allowing magnetic power to pass
Implementation Method 3
a transmitter coil that is driven to produce a time-varying magnetic field and a receiver coil that is positioned relative to the transmitter coil to receive the power transmitted in the time-varying magnetic field
Data Source
Figure 1~2
Figure 3~4A
Figure 4B~4C
AI summary
An EMI shield for a wireless power transmitter is presented. The EMI shield includes a patterned metallic layer that when positioned over a transmitting coil of the wireless power transmitter capacitively couples to the transmitting coil to capture electromagnetic radiation while allowing magnetic power to pass. In some embodiments, the patterned metallic layer may be a comb filter.