Wireless Charging FOD Feedback Using Q-Factor and Peak Frequency
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Solution Overview
Problem
Current wireless charging technologies face challenges in accurately detecting foreign objects in the charging area, which can lead to reduced efficiency and potential damage due to overheating, as existing methods struggle to reliably differentiate between a wireless power receiver and foreign objects based on quality factor values and peak frequencies.
Innovation Solution
A method and apparatus for detecting foreign objects in a wireless power transmitter that dynamically calibrate quality factor values by measuring shifts in peak frequencies and comparing them with predetermined thresholds, using a foreign object detection status packet to determine the presence of foreign objects and adaptively control power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If electromagnetic resonance method is used for wireless power transmission, then safety for electronic devices and human bodies is improved, but energy transmission efficiency deteriorates
Solution Approach 1:
The patent implements a feedback mechanism by measuring the quality factor of the resonance circuit and comparing it with a reference value to detect foreign objects. The system continuously monitors the resonance characteristics and adjusts power transmission based on the detected quality factor changes, creating a closed-loop control system that optimizes both safety and efficiency.
Solution Approach 2:
The patent changes the parameter being monitored from simple presence detection to quality factor measurement. By measuring the quality factor (Q-factor) of the resonance circuit, which changes when foreign objects are present, the system can distinguish between legitimate receivers and foreign objects, thereby improving both safety and energy efficiency through parameter-based detection.
2Difficulty of detecting and measuring
If quality factor measurement is used for foreign object detection, then detection capability is improved, but reliability deteriorates due to inability to differentiate between receivers and foreign objects
Solution Approach 1:
The patent introduces communication between the wireless power receiver and transmitter as an intermediary mechanism. The receiver actively communicates its identity and status to the transmitter, allowing the system to distinguish between legitimate receivers (which can communicate properly) and foreign objects (which cannot), thereby improving detection reliability.
Solution Approach 2:
The patent makes the wireless power receiver serve multiple functions: it not only receives power but also communicates its presence and validates its identity. This multi-functionality allows the system to use the same component (the receiver) for both power transfer and authentication, improving reliability without adding separate detection mechanisms.
3Duration of action of stationary object
If foreign objects are not detected and removed from charging area, then continuous power transmission is maintained, but power waste and overheating occur
Solution Approach 1:
The patent performs preliminary detection of foreign objects before initiating full power transmission. By measuring the quality factor and communicating with the receiver in advance, the system identifies and removes foreign objects before significant energy transfer occurs, preventing power waste and overheating while maintaining continuous operation when safe.
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, minimizes power waste, and prevents overheating by effectively distinguishing between wireless power receivers and foreign objects, ensuring safe and efficient charging operations.
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
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 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 controller, wherein the controller generates a foreign object detection (FOD) status packet including information on a reference quality factor or a reference peak frequency, and a packet having a length of eight bit, wherein the communication unit transmits the FOD status packet to the wireless power transmitter, wherein the communication unit receives, from the wireless power transmitter, a foreign object detection indicator indicating whether a foreign object is present in a charging area of the wireless power transmitter in response to the FOD status packet, wherein the controller performs differential bi-phase encoding for binary data of the packet having a length of eight bits, wherein the controller performs byte encoding for binary data of the differential bi-phase encoded packet, wherein the communication unit transmits the byte encoded packet to the wireless power transmitter, and wherein the byte encoding is inserting a start bit, a stop bit, and a parity bit into binary bit, stream of the differential bi-phase encoded packet.