Wireless Power FOD Calibration from Peak Frequency and Q-Factor Shifts
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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 waste
Solution Approach 1:
The patent 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 patent uses quality factor measurement as an intermediary indicator 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 quality factor caused by foreign objects, providing a safe and efficient detection mechanism that prevents harmful heating.
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 patent applies different detection thresholds and quality factor analysis methods for different detection scenarios. By customizing detection parameters locally for specific charging conditions and receiver types, the system achieves high detection sensitivity for foreign objects while maintaining compatibility with legitimate receivers, preventing false detections and charging interruptions.
Solution Approach 2:
The patent dynamically adjusts detection parameters such as quality factor thresholds and measurement frequencies based on the charging state and receiver characteristics. This parameter adaptation allows the system to distinguish between foreign objects and legitimate receivers across different operating conditions, maintaining both detection accuracy and charging reliability.
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
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; a memory configured to store information on a reference quality factor and a reference peak frequency; and a controller, wherein the controller generates a foreign object detection (FOD) status packet including information on the reference quality factor or the reference peak frequency, 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 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.