Segmented Shield for Wireless EV Charging EMI Mitigation
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Solution Overview
Problem
Wired charging solutions for electric vehicles are cumbersome and inefficient, and they emit electromagnetic radiation that can be detrimental to health and equipment.
Innovation Solution
A wireless electric vehicle charging system using a ferrite material and electrically conductive coils, with a shield comprising conducting and insulating regions to control induced currents and mitigate electromagnetic radiation emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If wireless charging systems use traditional continuous shields, then electromagnetic radiation is blocked, but induced currents are generated that create harmful RF emissions
Solution Approach 1:
The continuous shield is divided into multiple electrically conducting regions separated by electrically insulating regions. This segmentation prevents the formation of continuous induced current loops while maintaining electromagnetic radiation blocking capability, thereby reducing RF radiated emissions from the shield itself.
Solution Approach 2:
Different regions of the shield are given different electrical properties - conducting regions provide electromagnetic shielding while insulating regions interrupt current flow paths. This local differentiation allows the shield to block harmful radiation without generating harmful induced currents in the same locations.
2Reliability
If wired charging connections are used, then power transfer is reliable, but the system is cumbersome and inefficient
Solution Approach 1:
The mechanical cable connection system is replaced with a wireless electromagnetic power transfer system using magnetic coupling between coils. This eliminates the need for physical connectors while maintaining reliable power transfer through magnetic field coupling, significantly improving ease of operation.
3Object-affected harmful factors
If traditional solid shields are used in wireless charging, then electromagnetic radiation is blocked, but the shield generates induced currents that emit RF radiation
Solution Approach 1:
The solid shield is segmented into conducting and insulating regions that prevent continuous current loops. The insulating regions act as current interrupters, allowing the shield to block electromagnetic radiation from the power transfer device without generating harmful RF emissions from induced currents.
Solution Approach 2:
Electrically insulating regions are introduced as intermediary elements between conducting regions. These insulators mediate the electromagnetic field interaction by allowing field penetration for shielding while blocking current flow that would generate harmful RF emissions.
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
Enables efficient and safe wireless power transfer to electric vehicles while reducing electromagnetic radiation emissions that do not contribute to the charging process, enhancing safety and operational efficiency.
Implementation Method 1
The ferrite material and the at least one coil are configured to wirelessly transfer energy either from or to a second power transfer device of the WEVC system
Implementation Method 2
The plurality of electrically conducting regions and the one or more electrically insulating regions are configured to control induced currents in the at least one shield during operation of the WEVC system, the induced currents mitigating electromagnetic radiation emissions from the WEVC system
Data Source
AI summary
This disclosure provides systems, methods and apparatus for mitigating electromagnetic radiation emissions. In one aspect, a power transfer device of a wireless electric vehicle charging (WEVC) system is provided. The power transfer device includes a ferrite material and at least one electrically conductive coil. The ferrite material and the at least one coil are configured to wirelessly transfer energy either from or to a second power transfer device of the WEVC system. The power transfer device further includes at least one shield comprising a plurality of electrically conducting regions and one or more electrically insulating regions. The plurality of electrically conducting regions and one or more electrically insulating regions are configured to mitigate electromagnetic radiation emissions from the WEVC system that do not contribute to the wireless power transfer between the at least one electrically conductive coil and the second power transfer device.