Layered Magnetic Shielding for 3-Phase Wireless Power Transfer
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Solution Overview
Problem
Conventional wireless charging systems (WCSs) for high-power electric vehicle applications, particularly 3-phase systems, face challenges in controlling electromagnetic field (EMF) emissions, which exceed regulatory limits, necessitating effective shielding solutions to ensure safety and compliance.
Innovation Solution
A 3-phase wireless power transfer system incorporating magnetic material-based shields with multiple layers of high-permeability magnetic materials, strategically positioned on both the transmitter and receiver pads, to suppress magnetic field emissions by providing a low-reluctance path for stray magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional aluminum shields or ferrite extensions are used for high-power wireless charging pads, then magnetic field emissions are partially suppressed, but the shields become ineffective for double-D (DD) charging pads and cannot meet ICNIRP limits under misaligned conditions
Solution Approach 1:
The patent applies composite materials by combining multiple magnetic shielding materials (ferrite and mu-metal) in a layered configuration. This composite shield structure provides superior magnetic field suppression compared to single-material shields, achieving compliance with ICNIRP limits even under misaligned conditions for high-power DD charging pads
Solution Approach 2:
The shielding system is segmented into multiple functional layers: a ferrite layer for primary magnetic flux confinement, a mu-metal layer for enhanced shielding of residual fields, and an aluminum backplate for eddy current suppression. This segmentation allows each layer to address specific aspects of magnetic field management
2Area of stationary object
If large aluminum shields are deployed to suppress magnetic field emissions, then shielding coverage is increased, but the shields fail to effectively suppress MFE from DD charging pads and exceed regulatory limits
Solution Approach 1:
Instead of relying solely on large-area aluminum shields, the patent employs a composite material approach combining ferrite, mu-metal, and aluminum in specific configurations. This provides targeted magnetic field suppression that is more effective than extensive aluminum coverage alone
Solution Approach 2:
The shielding approach uses local quality by placing high-permeability magnetic materials (ferrite and mu-metal) in specific locations where magnetic field concentration occurs, rather than uniformly distributing shielding material across the entire area. This targeted placement optimizes shielding effectiveness
3Device complexity
If conventional single-layer magnetic shields are used, then device complexity is reduced, but shielding effectiveness is insufficient for high-power applications exceeding ICNIRP limits
Solution Approach 1:
The magnetic shielding system is segmented into multiple functional layers: ferrite for flux confinement, mu-metal for enhanced shielding, and aluminum backplate for eddy current suppression. This segmentation enables each layer to address specific shielding requirements, achieving superior performance for high-power applications
Solution Approach 2:
The patent employs composite materials by stacking ferrite, mu-metal, and aluminum layers to create a multi-functional shield structure. This composite approach provides synergistic shielding effects that exceed the capabilities of single-layer shields
4Object-affected harmful factors
If ferrite core extensions are implemented to reduce magnetic field emissions, then MFE reduction is achieved for limited power applications, but the solution cannot handle high-power applications of several hundred kilowatts
Solution Approach 1:
The patent extends the ferrite core concept by combining it with mu-metal and aluminum backplates in a composite shield structure. This enhanced composite configuration maintains the benefits of ferrite extensions while adding capabilities to handle high-power applications of several hundred kilowatts
Solution Approach 2:
The shielding system segments the magnetic field management function across multiple materials: ferrite for core flux confinement, mu-metal for leakage field suppression, and aluminum backplate for additional shielding. This segmentation enables the system to handle high power levels effectively
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 significantly reduces magnetic field emissions below regulatory limits, enhancing safety and compliance, while maintaining high power transfer efficiency, even under misaligned conditions.
Implementation Method 1
magnetic material-based shields with multiple layers of high-permeability magnetic materials, strategically positioned on both the transmitter and receiver pads, to suppress magnetic field emissions by providing a low-reluctance path for stray magnetic fields
Data Source
AI summary
A shield construction for transfer of wireless power is provided. The shield construction may be a magnetic shield having a plurality of layers and provided for a wireless transmitter or a wireless receiver, or both. The magnetic shield may include a first layer and a second layer, where the first layer may be nearer to a core than the second layer, and where the second layer may include a second layer area that is larger than a first layer area of the first layer. The wireless transmitter and the wireless receiver may be configured to multi-phase wireless power transfer.