Wireless Charging Foreign Object Detection via AGC Comparison
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for detecting foreign bodies during wireless charging of motor vehicle devices, such as metal objects or foils, are inefficient as they interfere with the charging process and can cause energy loss due to eddy current losses and heating, and existing solutions do not effectively differentiate between intended charging devices and foreign objects.
Innovation Solution
A charging device uses automatic gain control (AGC) values, comparing them with stored reference values to detect foreign bodies by monitoring changes in the electromagnetic field, allowing for real-time identification and adjustment of transmission power, and alerting the user to remove the foreign object or interrupting the charging process if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If wireless charging is performed using electromagnetic fields, then energy transfer to devices is enabled, but foreign objects in the charging area can cause eddy current losses and heating
Solution Approach 1:
The system performs preliminary detection of foreign objects in the charging area before initiating the wireless charging process. By using NFC communication to identify devices and detect foreign objects in advance, the system can prevent eddy current losses and heating by avoiding charging when foreign objects are present, thus maintaining energy transfer efficiency and preventing energy loss.
2Reliability
If foreign object detection is performed during charging, then safety is improved, but the charging process is interfered with and energy loss occurs
Solution Approach 1:
Foreign object detection is performed during the device identification phase before charging begins, using NFC communication to detect foreign objects in the charging area. This preliminary detection ensures charging safety without interfering with the charging process or causing energy loss, as the detection occurs independently of the power transfer phase.
Solution Approach 2:
The system uses NFC communication as an intermediary mechanism to detect foreign objects without directly using the wireless charging electromagnetic fields. This allows safety verification through a separate communication channel that does not cause eddy current losses or interfere with the charging process.
3Difficulty of detecting and measuring
If existing foreign object detection methods are used, then detection capability is provided, but they cannot effectively differentiate between intended charging devices and foreign objects
Solution Approach 1:
The system employs NFC communication as an intermediary to identify and differentiate between intended charging devices and foreign objects. Since NFC requires active participation and specific device characteristics, it can reliably distinguish authorized devices from foreign objects, achieving high measurement precision in differentiation.
Solution Approach 2:
The system changes the detection parameter from passive electromagnetic field monitoring to active NFC communication verification. This parameter change enables precise differentiation because NFC requires specific device responses and authentication, allowing the system to accurately identify intended devices versus foreign objects.
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
This solution enables efficient detection and prevention of foreign body interference during wireless charging, ensuring reliable and uninterrupted energy transfer to intended devices by accurately distinguishing between intended charging devices and foreign objects, thus optimizing the charging process.
Implementation Method 1
a primary coil Pri for wireless charging (e.g. according to WPC , Qi, etc.) of a device Tel to be charged (e.g. a mobile phone or smartphone or car key) via its (k0) secondary coil Sec coupled (to the primary coil Pri)
Implementation Method 2
For communication between the charging device on the part of the motor vehicle and the device Tel to be charged, e.g. communication by modulation via the charging coils Pri, Sek and/or near-field communication such as NFC via the charging coils Pri, Sek and/or other coils/antennas
Implementation Method 3
such as metal objects or foils, are inefficient as they interfere with the charging process and can cause energy loss due to eddy current losses and heating
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a method and to a device for detecting a foreign object (Fre) by means of a charging device (Pri, Bau) of a motor vehicle (Kfz), characterized in that the device is designed to compare (ECU; Bau) an amplification control value (AGC) of a component (Bau) to a saved reference value (Ref), in particular for the device (Tel) to be charged, and, in case of deviation therefrom, to specify (ECU; Bau) a detection of a foreign object (Fre).