Wireless Charging FOD Using Resonant Peak Frequency Feedback
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Solution Overview
Problem
Existing wireless charging systems face challenges in accurately detecting foreign objects, which can lead to reduced charging efficiency, overheating, and potential damage due to increased ambient temperature and power waste.
Innovation Solution
A method and apparatus for detecting foreign objects using a wireless power transmitter that measures quality factor and inductance values of a resonant circuit before a ping phase, determines a threshold value based on a reference quality factor, and compares these values to accurately identify foreign objects, with threshold values adjusted dynamically based on the reference quality factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wireless power transmission is performed in a charging area, then power transfer efficiency is improved, but foreign objects may be heated causing safety hazards and equipment damage
Solution Approach 1:
The system performs foreign object detection by measuring quality factor changes before initiating full power transmission. This preliminary detection action identifies potential foreign objects in the charging area, allowing the system to prevent or adjust power transmission to avoid heating foreign objects while maintaining efficient charging when the area is clear.
Solution Approach 2:
The quality factor measurement serves as an intermediary indicator to indirectly detect the presence of foreign objects. Instead of directly detecting foreign objects or their heating, the system uses quality factor changes of the resonant circuit as a mediator to infer foreign object presence, enabling safe power transmission decisions.
2Measurement precision
If foreign object detection sensitivity is increased to prevent heating, then detection accuracy improves, but false detections increase causing charging interruptions
Solution Approach 1:
The system dynamically adjusts the threshold for quality factor changes that trigger foreign object detection. By changing this parameter based on reference quality factor values and observed variations, the system achieves optimal balance between detection sensitivity and false alarm reduction, maintaining both detection accuracy and charging continuity.
Solution Approach 2:
The system uses feedback from quality factor measurements to continuously refine foreign object detection decisions. By comparing measured quality factor changes against reference values and adjusting detection thresholds based on observed patterns, the system reduces false detections while maintaining accurate foreign object identification, ensuring reliable charging operation.
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 approach enhances the accuracy of foreign object detection, minimizing power waste and equipment damage by effectively identifying and removing foreign objects during the charging process.
Implementation Method 1
Wireless power transmission or wireless energy transfer refers to technology for wirelessly transmitting electric energy from a transmitter to a receiver using the magnetic induction principle
Implementation Method 2
The magnetic induction method uses a phenomenon that, when two coils are located adjacent to each other and then current is applied to one coil, a magnetic flux is generated to cause an electromotive force in the other coil
Implementation Method 3
If a conductor which is not a wireless power receiver, that is, a foreign object (FO), is present in a wireless charging area, an electromagnetic signal received from a wireless power transmitter may be induced in the FO, thereby increasing in temperature
Implementation Method 4
an electromagnetic signal received from a wireless power transmitter may be induced in the FO, thereby increasing in temperature
Data Source
AI summary
A method of receiving power by a wireless power receiver, the method including transmitting, to a wireless power transmitter, a plurality of packets including a foreign object detection (FOD) status packet; and receiving, from the wireless power transmitter, a response signal indicating whether a foreign object is present in a charging area of the wireless power transmitter, wherein the response signal is determined using a measured peak frequency of a power signal transmitted by the wireless power transmitter and a reference peak frequency included in the FOD status packet received from the wireless power receiver, and wherein the plurality of packets further include at least one of a signal strength packet, an end power transfer packet, a power control hold-off packet, a configuration packet, an identification packet for transmitting receiver identification information, an extended identification packet, a general request packet, a special request packet, a control error packet, a renegotiation packet, a 24-bit received power packet, an eight-bit received power packet, and a charging status packet.