Wireless Charger E-Field Shield with Segmented Conductors
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Solution Overview
Problem
Wireless charging systems cause interference with AM radio reception and generate excessive heat, leading to inefficiencies and safety issues due to magnetic interference and heat dissipation challenges.
Innovation Solution
A shielding arrangement with parallel conductors and a solid conductive junction on a printed circuit board is used to attenuate electromagnetic fields, particularly in the AM band, while allowing magnetic fields to pass through, and incorporates a thermally conductive material to manage heat dissipation without eddy current formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If magnetic shielding is provided around the primary secondary system, then magnetic interference is reduced, but the shielding material may cause eddy current losses and heat generation
Solution Approach 1:
The shielding structure is segmented into multiple parallel conductive bars spaced at specific intervals, rather than using a continuous solid shield. This segmentation allows magnetic fields to pass through the gaps between bars while the bars themselves provide E-field shielding and heat dissipation pathways without forming closed loops that would generate eddy currents.
Solution Approach 2:
Different regions of the shielding structure have different properties: the parallel conductive bars provide E-field shielding and thermal conduction, while the gaps between bars allow magnetic field penetration. The bars are positioned at specific lateral distances optimized for the target frequency range to achieve frequency-selective shielding characteristics.
2Temperature
If a solid electrically conductive material is placed above the coil to function as a heat sink, then heat dissipation is improved, but eddy current formation occurs
Solution Approach 1:
The solid conductive heat sink material is segmented into parallel conductive bars with gaps between them. This segmentation provides thermal conduction pathways through the bars while breaking the closed loops that would form eddy currents, thus enabling heat dissipation without significant energy loss.
Solution Approach 2:
The parallel conductive bars act as an intermediary structure between the charging coil and the environment. They provide thermal conduction to dissipate heat from the coil while their open structure prevents eddy current formation, mediating between the need for heat removal and the need to avoid energy loss.
3Object-affected harmful factors
If the primary signal frequency is designed below the AM radio band, then AM radio reception interference is reduced, but harmonics still spill over into the AM band
Solution Approach 1:
The E-field shield converts the harmful E-field radiation that causes AM radio interference into a beneficial effect by providing a controlled path for E-field termination. The parallel conductive bars capture and dissipate the E-field energy, converting the harmful electromagnetic radiation into heat that is then conducted away, thereby eliminating the interference problem.
4Object-affected harmful factors
If parallel conductors are arranged closer together to improve E-field shielding, then AM band interference is reduced, but the structure becomes more complex
Solution Approach 1:
Multiple functions are merged into the single parallel bar structure: E-field shielding, thermal conduction, and mechanical support. The same conductive bars that provide E-field shielding also serve as heat sinks, eliminating the need for separate shielding and cooling components, thus reducing overall system complexity despite the detailed geometry of the bars.
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 AM radio interference and prevents excessive heat buildup, maintaining efficient wireless charging with minimal eddy current losses and improved heat management.
Implementation Method 1
The first predetermined lateral distance is responsive to a frequency of an electromagnetic energy that is desired to be attenuated as the electromagnetic energy is propagated through the shielding arrangement
Implementation Method 2
incorporates a thermally conductive material to manage heat dissipation without eddy current formation
Data Source
AI summary
A shielding arrangement for preventing AM radio interference when a wireless charger is used in a vehicle has a plurality of parallel conductors arranged at a distance from one another responsive to a frequency desired to be attenuated. An interconnection arrangement includes a solid conductive junction and connects the conductors to one another without forming loops, and to ground. The conductors are traces disposed on a PCB. Additional parallel conducts are disposed on the other side of the PCB at an orthogonal orientation with respect to the first conductors. The spacing between the conductors is determined in response to the frequency desired to be attenuated, as well as frequencies thereabove that are desired to be propagated therethrough, such as mobile telephone signals. The solid conductive junction that is disposed on the printed circuit board is electrically and thermally conductive, such as copper.