Wireless Power FOD Using Quality Factor and Inductance Thresholds
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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 the ping phase, determines a threshold value based on a reference quality factor, and compares these values with a dynamically adjusted threshold to accurately identify foreign objects.
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 the wireless power transfer process. By measuring quality factor and inductance values in advance and comparing them against dynamically adjusted thresholds, the system identifies foreign objects in the charging area before they can be heated by high-power electromagnetic fields, thus preventing the harmful effect while maintaining efficient power transfer when safe
Solution Approach 2:
The system continuously monitors quality factor and inductance parameters during the charging process and dynamically adjusts detection thresholds based on reference quality factor values. This feedback mechanism allows the system to adapt to changing conditions and accurately detect foreign objects while maintaining optimal power transfer efficiency under normal operating conditions
2Ease of operation
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 employs multiple electrical parameters (quality factor, inductance, and their rate of change) for foreign object detection rather than relying on a single threshold. By analyzing changes in these parameters over time and comparing them against dynamically adjusted thresholds based on reference values, the system achieves high detection accuracy while maintaining simple operation through automated multi-parameter analysis
Solution Approach 2:
The detection thresholds are not fixed but are dynamically adjusted based on reference quality factor values and measured parameter changes. This dynamic threshold adjustment allows the system to adapt to different charging conditions and device types, significantly improving detection accuracy while the automated nature of the process maintains ease of operation
3Productivity
If foreign objects are not detected, then charging continues uninterrupted, but power waste and equipment damage occur due to overheating
Solution Approach 1:
The system performs foreign object detection before initiating power transfer and continuously monitors during charging. By detecting foreign objects in advance and interrupting charging when foreign objects are identified, the system prevents energy waste and equipment damage while minimizing interruptions to legitimate charging operations through accurate detection algorithms
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 thresholds based on reference quality factors and inductance values, thereby improving charging efficiency and safety.
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 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 of the resonant circuit when the object is detected
Implementation Method 4
measuring a inductance value of the resonant circuit when the object is detected
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 a size of the message included in the each packet is identified on the basis of a value of the header.