Coil Array Foreign Object Detection for Wireless Charging Safety
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Solution Overview
Problem
Wireless charging systems face safety issues due to the risk of foreign objects, such as metal objects or living creatures, being present between the transmit and receive coils, which can lead to heating, spontaneous combustion, or health hazards, and affect charging efficiency.
Innovation Solution
A foreign object detection method and apparatus using a coil array with symmetrical detection coils and a foreign object detection circuit that determines abnormal signal thresholds based on induction signals to identify and remove foreign objects, incorporating dynamic threshold adjustment and excitation source-based detection to enhance accuracy and adaptability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a foreign object detection system is implemented in wireless charging, then safety is improved, but device complexity increases
Solution Approach 1:
The detection system divides the detection area into multiple regions using a coil array with multiple detection coils, allowing localized foreign object detection and reducing the complexity of analyzing the entire detection area as a single unit
Solution Approach 2:
The detection coils serve dual purposes: they are part of the wireless power transmission system and simultaneously function as sensors for foreign object detection, eliminating the need for separate detection hardware and reducing overall system complexity
2Measurement precision
If dynamic threshold adjustment is used based on induction signals, then detection accuracy is improved, but processing time increases
Solution Approach 1:
The system pre-calculates and stores abnormal-value thresholds during an initialization phase or during periods when no foreign objects are present, so that during actual detection operations, the pre-computed thresholds can be quickly applied without real-time calculation delays
Solution Approach 2:
The system continuously monitors induction signals and dynamically adjusts thresholds based on feedback from the environment, learning normal variations over time and adapting to different operating conditions, which improves accuracy while maintaining efficient processing through adaptive rather than purely computational approaches
3Area of stationary object
If a coil array with multiple detection coils is used, then detection coverage is improved, but system complexity increases
Solution Approach 1:
Multiple detection coils are electrically connected and operated as an integrated array, sharing common control and processing resources, which reduces the complexity that would otherwise result from having completely independent detection systems for each coil
Solution Approach 2:
The same coil array structure serves both wireless power transmission and foreign object detection functions, eliminating the need for separate dedicated detection hardware and reducing overall system complexity while maintaining comprehensive detection coverage
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 effectively improves wireless charging safety by timely detection and removal of foreign objects, reducing the risk of hazards and enhancing charging efficiency while minimizing interference from environmental factors.
Implementation Method 1
A transmit coil in the power transmitting apparatus and a receive coil in the power receiving apparatus may transmit energy through electromagnetic induction
Implementation Method 2
When there is a metal foreign object between the transmit coil and the receive coil, the metal foreign object may heat due to an eddy effect
Data Source
AI summary
This application provides a foreign object detection method and apparatus, and a wireless charging system. The foreign object detection apparatus includes a coil array and a foreign object detection circuit. The coil array includes at least one coil group, and each coil group includes four detection coils whose locations are symmetrical to each other. The foreign object detection circuit determine an abnormal-value threshold of each coil group based on induction signals of each coil group and that are obtained in a first time period, and detect, based on the abnormal-value threshold and the induction signals of each coil group, whether there is a foreign object; when it is determined that there is no foreign object, detect, based on the signal threshold of each coil group and induction signals that are of each coil group and that are obtained in a second time period, whether there is a foreign object.