Wireless Power FOD via Peak Frequency and Resonant Circuit Sensing
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Solution Overview
Problem
Existing wireless charging systems face challenges in accurately detecting foreign objects, which can lead to reduced 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 the ping phase, determines a threshold value based on a reference quality factor, and compares these values to accurately identify foreign objects, with the threshold value adjusted dynamically according to the reference quality factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If wireless power transmission is performed using electromagnetic induction or resonance, then power can be transferred wirelessly to devices, but foreign objects in the charging area may be heated due to induced electromagnetic signals
Solution Approach 1:
The system performs foreign object detection before initiating full wireless power transmission by measuring quality factor and inductance values during a preliminary detection phase. This preliminary action identifies potential foreign objects that could be heated, allowing the system to prevent power transmission to areas with foreign objects present
Solution Approach 2:
The patent uses quality factor and inductance measurements as intermediary indicators to indirectly detect the presence of foreign objects. Instead of directly detecting foreign objects or their heating, the system measures changes in the resonant circuit's electrical characteristics, which serve as mediators to infer foreign object presence and prevent harmful heating
2Reliability
If traditional foreign object detection methods are used, then detection can be performed, but accuracy is insufficient leading to false positives or missed detections
Solution Approach 1:
The system changes the detection parameters by using multiple electrical characteristics (quality factor and inductance values) instead of a single parameter. By measuring both Q-factor and inductance changes in the resonant circuit, the system creates a more precise detection profile that reduces false positives and improves foreign object detection accuracy
Solution Approach 2:
The system implements feedback by comparing measured quality factor and inductance values against reference values or thresholds. This feedback mechanism allows the system to continuously monitor and adjust its detection decisions, improving reliability by confirming foreign object presence through multiple measurement comparisons rather than single-point detection
3Productivity
If foreign objects are not accurately detected, then wireless charging can proceed without interruption, but power waste and equipment damage occur due to overheating
Solution Approach 1:
The system performs preliminary foreign object detection before initiating power transmission, identifying foreign objects in advance. This prevents power waste by avoiding transmission to areas with foreign objects, while the preliminary nature of the detection ensures charging can quickly resume once the area is cleared, maintaining productivity
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 dynamically adjusting the threshold values based on the reference quality factor and inductance, thereby improving the reliability of wireless charging systems.
Implementation Method 1
wireless power transmission technology... uses the magnetic induction principle
Implementation Method 2
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 wireless power receiver that receives power from a wireless power transmitter, the wireless power receiver including a communication unit configured to communicate with the wireless power transmitter; and a main controller, wherein the main controller generates a plurality of packets including a foreign object detection (FOD) status packet, wherein the communication unit transmits the FOD status packet to the wireless power transmitter, and the communication unit receives, 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, wherein each of the plurality of packets includes a preamble, a header, a message, and a checksum for identifying whether an error occurs in each packet, and wherein the header is configured to identify a type of the each packet.