Wireless Charging FOD Using Quality Factor Calibration
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Solution Overview
Problem
Existing wireless charging technologies face challenges in accurately detecting foreign objects in the charging area, leading to reduced efficiency and potential damage due to overheating.
Innovation Solution
A method and apparatus for detecting foreign objects using quality factor calibration based on peak frequency shifts and slope comparisons, involving a quality factor measurement unit, peak frequency search, and communication units to determine the presence of foreign objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
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 energy waste
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 is improved, but false detections increase reducing charging availability
Solution Approach 1:
The system dynamically adjusts detection thresholds and quality factor reference values based on the specific receiver device being charged. By adapting the detection parameters to each device type and charging scenario, the system maintains high detection sensitivity while reducing false positives that would otherwise reduce charging availability.
Solution Approach 2:
The system changes detection parameters including quality factor thresholds, measurement frequencies, and reference values based on the charging state and device type. This parameter adaptation allows the system to optimize between detection sensitivity and false alarm reduction, maintaining both accuracy and charging availability.
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
Accurately detects foreign objects, minimizing power waste and overheating, and improving detection capability by dynamically calibrating quality factors and adaptively applying detection methods.
Implementation Method 1
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 2
The electromagnetic resonance method uses an electric field or a magnetic field instead of using electromagnetic waves or current
Implementation Method 3
measuring a quality factor value corresponding to a reference operating frequency when an object is detected, searching for a current peak frequency having a maximum quality factor value within an operating frequency band
Implementation Method 4
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
Data Source
AI summary
A power transmission method for a wireless power transmitter, the power transmission method including receiving, from a wireless power receiver, a packet including a foreign object detection (FOD) status packet; determining whether a foreign object is present in a charging area of the wireless power transmitter based on the FOD status packet; and generating a foreign object detection indicator indicating whether the foreign object is present in the charging area of the wireless power transmitter based on a result of the determination and transmitting the generated foreign object detection indicator to the wireless power receiver, wherein the FOD status packet includes information on a reference quality factor or a reference peak frequency, and wherein the packet further includes 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 extension identification packet, a general request packet, a special request packet, a control error packet, a renegotiation packet, a 24-bit reception power packet, an eight-bit reception power packet, and a charging status packet.