Wireless Power Coil Shielding Layout for Leakage Field Control
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Solution Overview
Problem
The increasing power transmission in wireless charging systems leads to higher electromagnetic interference (EMI) and electromagnetic wave human exposure (EMF), due to leakage magnetic fields.
Innovation Solution
A wireless power transmission apparatus is designed with a shielding plate and a transmission coil, where a shielding member surrounds the transmission coil to minimize EMI and EMF. Additionally, a shielding layer is disposed around the transmission coil to offset the magnetic field, and pattern coils are used to reduce the capacitance value of the resonance capacitor, thereby reducing component size and improving shielding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transmission power is increased to provide rapid charging, then charging speed is improved, but electromagnetic interference (EMI) and electromagnetic wave human exposure (EMF) increase due to leakage magnetic fields
Solution Approach 1:
The patent applies the principle of converting harmful magnetic fields into beneficial effects by using shielding members that generate opposing magnetic fields to cancel out leakage fields. The shielding members are positioned around the transmission coil and carry currents that generate magnetic fields opposite to the leakage fields, thereby neutralizing the harmful EMI and EMF while maintaining high transmission power for rapid charging
Solution Approach 2:
The patent introduces shielding members as intermediary elements between the transmission coil and the surrounding environment. These shielding members act as mediators that intercept and neutralize the leakage magnetic fields before they can cause harmful EMI and EMF effects on nearby devices and human exposure
2Object-generated harmful factors
If shielding members are added to reduce EMI and EMF, then electromagnetic interference is minimized, but device complexity increases
Solution Approach 1:
The patent employs thin-film shielding members that can be flexibly positioned around the transmission coil. These thin-film structures provide effective magnetic field shielding while maintaining a compact and relatively simple overall device structure, avoiding the need for bulky shielding components that would significantly increase device complexity
3Volume of moving object
If resonance capacitor size is reduced to minimize component size, then component size is decreased, but transmission efficiency and shielding performance deteriorate
Solution Approach 1:
The patent utilizes parameter changes in the resonance circuit by adjusting the inductance values of pattern coils and optimizing the capacitance values of resonance capacitors. By carefully selecting these parameters, the patent achieves effective magnetic field shielding and maintains high transmission efficiency while using smaller-capacitor components, thus resolving the contradiction between component size and performance
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 proposed solution effectively minimizes EMI and EMF by shielding the magnetic fields, reduces the component size of the resonance capacitor, and enhances transmission efficiency and shielding performance.
Implementation Method 1
the shielding plate is disposed on the lower side of the transmission coil and the shielding member is disposed on the side of the transmission coil. Thus, the magnetic field formed at the rear of the transmission coil is shielded by the shielding plate and the magnetic field formed on the side of the transmission coil is offset by the shielding member
Implementation Method 2
a shielding layer is disposed around the transmission coil, and when a magnetic field is generated in the transmission coil, the phase of the current flowing in the transmission coil is reversed by the magnetic field generated in the transmission coil in the shielding layer and a current having the same amplitude flows, and a magnetic field formed on the side of the transmission coil is offset by a magnetic field generated by the current
Implementation Method 3
the capacitance value of the resonance capacitor can be reduced by increasing the total inductance value due to the at least one pattern coil by making at least one pattern coils constituting the shielding layer
Data Source
AI summary
A wireless power transmission apparatus includes a shielding plate, a transmission coil on the shielding plate, and a shielding member disposed on the shielding plate and configured to surround the transmission coil. The shielding plate may shield a magnetic field formed to a lower side of the transmission coil. The shield member can offset the magnetic field formed on the side of the transmission coil. Thus, the embodiment can minimize EMI or EMF caused by the magnetic field formed on the lower side and the side of the transmission coil.