Wireless Power FOD Using Peak-Frequency-Calibrated Quality Factor
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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 comparing measured peak frequencies with reference values, using a quality factor slope calculated from output voltage levels within an operating frequency band, and applying adaptive detection based on these calibrations to determine the presence of foreign objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If electromagnetic signals are transmitted for wireless power transfer, then power transmission capability is improved, but foreign objects in the charging area may be heated causing safety issues
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 safe wireless charging operation.
2Difficulty of detecting and measuring
If quality factor values are used to detect foreign objects, then detection capability is improved, but reliability is reduced due to difficulty in differentiating between receivers and foreign objects
Solution Approach 1:
The system dynamically adjusts the quality factor threshold based on the operating frequency band. By calibrating the threshold to match the specific frequency characteristics of the wireless power transmission system, the method enables reliable differentiation between receivers and foreign objects, improving detection reliability while maintaining accurate foreign object identification.
3Measurement precision
If dynamic calibration with frequency comparison is implemented, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The system implements a feedback mechanism where the measured quality factor is compared against a dynamically calibrated threshold that accounts for operating frequency variations. This feedback-based approach automatically adjusts detection criteria based on actual system conditions, achieving high detection accuracy through intelligent algorithmic compensation rather than complex hardware modifications.
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, thereby ensuring safe and efficient 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.
Implementation Method 2
an electromagnetic signal received from a wireless power transmitter may be induced in the FO, thereby increasing in temperature
Implementation Method 3
measuring a quality factor value, which corresponds to a reference operation frequency, when an object is sensed; searching for a current peak frequency having a maximum quality factor value within an operation frequency band
Data Source
AI summary
A power transmission method for a wireless power transmitter, the power transmission method including receiving, from a wireless power receiver, a foreign object detection (FOD) status packet including information on a reference quality factor or a reference peak frequency; determining whether a foreign object is present in a charging area of the wireless power transmitter based on the FOD status packet; and generating a foreign object detection indicator indicating whether the foreign object is present in the charging area of the wireless power transmitter based on a result of the determination and transmitting the generated foreign object detection indicator to the wireless power receiver, wherein the FOD status packet has a length of two bytes, wherein one byte of the FOD status packet includes a six-bit reservation field and a two-bit mode field, and wherein all bits of the reservation field are recorded as zero.