Wireless Charging FOD Using Dynamic Q-Factor 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, resulting in power waste and equipment damage.
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 with a dynamically adjusted threshold to accurately identify foreign objects, incorporating a weight that increases with the reference quality factor value.
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 ping phase and power transmission. By measuring quality factor and inductance values in advance and comparing them against dynamically adjusted thresholds, the system identifies foreign objects proactively, preventing them from being exposed to high-power electromagnetic fields that would cause heating.
Solution Approach 2:
The system continuously monitors quality factor and inductance parameters during the charging process and compares real-time measurements against reference values. When deviations indicate foreign object presence, the system provides feedback to adjust or terminate power transmission, preventing harmful heating while maintaining efficient charging when no foreign objects are present.
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 dynamically adjusts detection thresholds based on reference quality factor values and operating conditions. By changing the threshold parameter adaptively rather than using fixed values, the system achieves higher detection accuracy across different charging scenarios while maintaining simple operation through automated threshold selection.
Solution Approach 2:
The detection system combines multiple parameters (quality factor, inductance, and dynamically adjusted thresholds) into a composite detection approach. This multi-parameter composite method improves accuracy by cross-validating multiple indicators rather than relying on a single measurement, reducing false positives and missed detections.
3Productivity
If foreign objects are not detected accurately, then charging can proceed without interruption, but power waste and equipment damage occur
Solution Approach 1:
The system performs detection before the ping phase and at critical transition points in the charging process. By identifying foreign objects in advance before significant power transfer occurs, the system prevents both unnecessary charging interruptions (maintaining productivity when safe) and energy waste (stopping charging when foreign objects are detected).
Solution Approach 2:
The system implements continuous feedback monitoring of quality factor and inductance parameters during charging. When foreign objects are detected through parameter deviations, feedback triggers immediate charging termination or power reduction, preventing energy waste and equipment damage while allowing uninterrupted charging to continue when parameters remain within normal ranges.
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 factor values, thereby improving the reliability of wireless charging systems.
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
The rectenna is a combination of an antenna and a rectifier and means an element for directly converting RF power into DC power
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
Implementation Method 5
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, 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.