Wireless Charging FOD Using Peak-Frequency and Q-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 overheating, which can result in power waste and damage to the transmitter and receiver.
Innovation Solution
A method and apparatus for detecting foreign objects using dynamic calibration of quality factor values based on shifts in peak frequencies, comparing measured quality factor slopes with predetermined thresholds, and adaptively applying detection methods to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
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 loss
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 improves, but false detection of legitimate receivers increases causing charging interruptions
Solution Approach 1:
The system applies different quality factor threshold criteria for different detection scenarios. Instead of using a single universal threshold, it establishes specific threshold ranges that account for the different electromagnetic characteristics of foreign objects versus legitimate wireless power receivers, enabling accurate differentiation without false positives.
Solution Approach 2:
The system uses bidirectional communication between transmitter and receiver to verify device identity and status. The receiver provides feedback signals that confirm its legitimacy, allowing the system to distinguish authenticated receivers from foreign objects even when quality factor changes are similar, preventing false detection interruptions.
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 foreign objects and intended receivers, ensuring safe and efficient wireless charging operations.
Implementation Method 1
wireless power transmitter that generates an electromagnetic field for wirelessly transmitting power
Implementation Method 2
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 reception method for a wireless power receiver, the power reception method including storing information on a reference quality factor and a reference peak frequency; generating a foreign object detection (FOD) status packet including the information on the reference quality factor and the reference peak frequency; transmitting the FOD status packet to a wireless power transmitter; and receiving 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 FOD status packet has a length of two bytes, wherein one byte of the FOD status packet includes a 6-bit reservation field and a 2-bit mode field, and wherein all bits of the reservation field are recorded as zero.