Wireless Power Transmitter Shielding Structure
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Solution Overview
Problem
Wireless power transfer systems face challenges in reducing electromagnetic interference (EMI) caused by the electric field induced by transmitting coils, particularly in environments like vehicles where EMI can disrupt electronics.
Innovation Solution
The implementation of shields with conductive traces forming planar patterns, positioned between the transmitting and receiving coils, which filter and attenuate the electric field while minimizing the attenuation of the magnetic field, thereby reducing EMI without affecting the efficiency of power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shield is introduced to filter the electric field, then EMI is reduced, but the complexity of the device increases
Solution Approach 1:
The patent employs thin film shields deposited on the substrate to filter electric fields. These thin film structures provide EMI protection while maintaining device compactness and minimizing added complexity compared to bulk shielding materials.
Solution Approach 2:
The patent modifies substrate parameters by depositing conductive materials (such as transparent conductive oxides) to create shield regions. This changes the electrical properties of the substrate locally, enabling EMI filtering without adding separate complex shielding components.
2Object-affected harmful factors
If the shield is positioned close to the transmitting coil, then EMI filtering is improved, but the magnetic field attenuation increases
Solution Approach 1:
The patent creates localized shield regions with specific conductive patterns on the substrate rather than using uniform shielding. This allows electric field filtering to be applied selectively in areas where it is most needed, while preserving magnetic field coupling in regions critical for power transfer.
Solution Approach 2:
The patent uses composite structures combining dielectric substrate materials with conductive material layers (such as transparent conductive oxides or metal traces). This composite approach provides electric field shielding while maintaining magnetic field permeability, thus protecting against EMI without significantly attenuating the power transfer magnetic field.
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 effectively reduces EMI emissions, particularly in the AM radio band, while maintaining nearly the same efficiency of power transfer, ensuring compliance with electromagnetic interference limits and minimizing disruptions to sensitive electronics.
Implementation Method 1
The shield can be configured to filter an electric field induced by the transmitting coil
Implementation Method 2
A varying current in a primary winding creates a varying magnetic flux, and thus induces a varying magnetic field through a secondary winding. The varying magnetic field induces a varying electromotive force (EMF), or 'voltage', in the secondary winding. This effect can be referred to as inductive coupling.
Data Source
AI summary
A wireless power transmitter can include a transmitting coil configured to wirelessly transmit power to a receiving coil. The wireless power transmitter can include a shield residing on a given side of a substrate spaced apart from the transmitting coil. The shield can be configured to filter an electric field induced by the transmitting coil.