Wireless Power Foreign Object Detection with Peak-Frequency 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 due to increased ambient temperature, which can damage the wireless power transmitter and receiver.
Innovation Solution
A method for detecting foreign objects by dynamically calibrating the measured quality factor value based on the shift of the current peak frequency from a reference peak frequency, calculating the quality factor slope, and comparing it with predetermined thresholds to accurately identify the presence of foreign objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If wireless power transmission is performed using electromagnetic induction or resonance, then power transfer capability is improved, but foreign object detection accuracy deteriorates due to temperature increase and electromagnetic interference
Solution Approach 1:
The patent performs foreign object detection before initiating power transmission by measuring the quality factor of the transmitter coil at its resonant frequency. This preliminary measurement establishes a baseline quality factor value that is compared against threshold values to detect foreign objects. By conducting detection prior to power transmission, the system avoids the interference and temperature effects that occur during active charging, thereby maintaining high detection accuracy while enabling safe power transfer.
2Device complexity
If quality factor measurement is performed at reference operating frequency, then detection process is simplified, but detection accuracy deteriorates due to frequency drift
Solution Approach 1:
The patent dynamically adjusts the frequency at which quality factor measurements are taken based on the actual resonant frequency of the transmitter coil. Instead of using a fixed reference frequency, the system identifies the peak frequency of the coil's impedance curve and performs quality factor measurements at this dynamically determined frequency. This adaptation to frequency drift ensures accurate foreign object detection even when operating conditions change, while maintaining a relatively simple measurement process.
3Productivity
If foreign object detection is not performed, then charging efficiency is maintained, but harmful effects increase due to overheating and potential damage
Solution Approach 1:
The patent performs foreign object detection before initiating power transmission by measuring the quality factor of the transmitter coil. The measured quality factor is compared against pre-established threshold values to determine whether a foreign object is present. If the quality factor falls outside the acceptable range, the system prevents power transmission from occurring, thereby avoiding overheating and damage to the wireless charging system while minimizing impact on charging efficiency through rapid detection and prevention.
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 detection of foreign objects, minimizing power waste and overheating, thereby improving the reliability and safety 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
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
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AI summary
The present invention relates to a method for detecting foreign material, and an apparatus and a system therefor, and a method for detecting foreign material in a wireless power transmitter, according to one embodiment of the present invention, comprises the steps of: 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; receiving, form a wireless power receiver, a foreign material detection state packet including information on a reference peak frequency; correcting the measured quality factor value by using a difference value between the current peak frequency and the reference peak frequency; and determining whether the foreign material exists by comparing the corrected quality factor value with a predetermined quality factor threshold value. Therefore, the present invention has an advantage of enabling foreign material to be more effectively and accurately detected.