Segmented Reflector Antenna for Wireless EV Charging Safety
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Solution Overview
Problem
Existing wireless charging systems for electric vehicles lack effective living-object protection, as they do not adequately detect and prevent the charging of living beings within the wireless power transfer region, potentially leading to unsafe energy exposure.
Innovation Solution
A base wireless power transfer system incorporating a living-object protection subsystem with a reflector and radiator antenna configuration that transmits and receives RF signals, analyzing the reflected signals to determine the presence of objects and inhibit charging when a living object is detected, using a non-solid metal sheet reflector to reduce eddy currents and energy absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a solid metal sheet reflector is used to direct RF signals away from the power transfer circuitry, then the main beam directionality is improved, but eddy currents are generated causing energy loss and heating
Solution Approach 1:
The solid metal sheet reflector is segmented into multiple separate conductive elements arranged in a specific pattern. This segmentation breaks the continuous metal path that would otherwise support large eddy currents, thereby reducing energy loss and heating while maintaining the reflective function to direct the main beam away from the power transfer circuitry
Solution Approach 2:
Different regions of the reflector structure are designed with different properties - certain areas have conductive elements optimized for reflecting RF signals to achieve proper main beam directionality, while the overall segmented structure minimizes eddy current formation. The local arrangement of conductive elements provides the necessary directional control without creating continuous current paths
2Use of energy by moving object
If a solid metal sheet reflector is used to transmit RF signals, then the signal transmission efficiency is improved, but the reflector absorbs excessive energy and heats up
Solution Approach 1:
The reflector is divided into discrete conductive elements rather than using a solid metal sheet. This segmentation allows the structure to efficiently reflect and transmit RF signals through the arranged elements while preventing the formation of large eddy currents that would cause excessive heating, thus maintaining transmission efficiency without excessive temperature rise
Solution Approach 2:
The reflector structure incorporates a non-solid, porous-like configuration with gaps between conductive elements. This porous arrangement reduces the material density and interrupt eddy current paths, allowing RF signals to pass through more efficiently while minimizing energy absorption and heat generation in the reflector material
3Measurement precision
If the antenna beam is directed toward the region of interest for living object detection, then the detection capability is improved, but the power transfer circuitry is exposed to potential RF interference
Solution Approach 1:
The harmful RF interference is extracted and redirected away from the power transfer circuitry by positioning the reflector between the antenna and the power circuitry. The reflector captures RF signals that would otherwise interfere with the power transfer system and redirects them toward the region of interest, thereby protecting the power circuitry while maintaining detection capability
Solution Approach 2:
The reflector serves as an intermediary element between the antenna and the power transfer circuitry. It mediates the RF signal paths by reflecting signals toward the region of interest for detection while preventing direct RF interference from reaching the power transfer circuitry, thus protecting the system without compromising detection functionality
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 system effectively prevents charging power from being provided to living objects, enhancing safety by ensuring that energy is only transferred when no living beings are in the danger zone, while maintaining efficient power transfer to electric vehicles.
Implementation Method 1
power transfer circuitry communicatively coupled to the power-coupling element and configured to provide energy to the power-coupling element to produce a magnetic field
Implementation Method 2
an antenna configured to transmit a first radio-frequency (RF) signal with a main beam directed away from the power transfer circuitry and to receive a second RF signal
Implementation Method 3
a reflector with the reflector being disposed between the radiating element and the power transfer circuitry
Implementation Method 4
using a non-solid metal sheet reflector to reduce eddy currents and energy absorption
Data Source
AI summary
Techniques for providing radio-frequency signals to a region of interest for a living-objection protection (LOP) system are provided. An example base wireless power transfer system includes a power-coupling element and a power transfer circuitry configured to provide energy to the power-coupling element to produce a magnetic field, and a living-object protection subsystem including an antenna configured to transmit a first radio-frequency (RF) signal with a main beam directed away from the power transfer circuitry and to receive a second RF signal, the antenna including a radiating element and a reflector with the reflector being disposed between the radiating element and the power transfer circuitry and comprising a metal sheet disposed over an area, the metal sheet defining at least one opening within the area and between the radiating element and the power transfer circuitry.