Wireless Charging Foreign Object Detection via 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, which can lead to reduced efficiency and potential damage due to overheating.
Innovation Solution
A method for detecting foreign objects using quality factor calibration based on peak frequency shifts, involving the measurement of quality factor values at current and reference frequencies, and comparing these values with predetermined thresholds to determine the presence of foreign objects.
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 (Q-factor) of the resonant circuit and comparing it with a reference value to detect foreign objects. The system continuously monitors the resonant frequency and Q-factor changes, and adjusts or stops power transmission based on the detection results, creating a closed-loop control system that balances safety and efficiency
2Device complexity
If quality factor measurement is performed without frequency calibration, then detection process is simplified, but detection accuracy deteriorates due to frequency shifts
Solution Approach 1:
The patent applies preliminary action by performing frequency calibration before quality factor measurement. The system first sweeps through a frequency range to identify the peak resonant frequency, then uses this calibrated frequency as the basis for accurate Q-factor measurement. This preliminary frequency identification step ensures that subsequent measurements are performed at the correct operating point
Solution Approach 2:
The patent replaces direct physical measurement of foreign objects with an indirect electrical measurement approach. Instead of mechanically detecting foreign objects, the system measures electrical parameters (current, voltage, frequency, Q-factor) of the resonant circuit, which change in response to foreign object presence. This substitution enables non-contact, automated detection
3Productivity
If foreign object detection is not performed accurately, then charging speed is maintained, but overheating and potential damage occur
Solution Approach 1:
The system uses feedback control by continuously monitoring the Q-factor and comparing it with predetermined thresholds. When the Q-factor drops below the threshold indicating foreign object presence, the system responds by stopping or adjusting power transmission, preventing overheating while enabling safe charging operation
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 method enhances the accuracy of foreign object detection, minimizing power waste and preventing overheating by adaptively adjusting to frequency shifts, thereby improving the reliability of wireless charging systems.
Implementation Method 1
a coil electromagnetically coupled to the external, a resonant circuit that includes at least the coil
Implementation Method 2
a resonant circuit that includes at least the coil, and a detecting section that superimposes a measurement signal for measuring the Q-factor of the resonant circuit
Implementation Method 3
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 4
The electromagnetic resonance method uses an electric field or a magnetic field instead of using electromagnetic waves or current
Implementation Method 5
This technology is a RF wireless power transmission method using a rectenna. The rectenna is a combination of an antenna and a rectifier and means an element for directly converting RF power into DC power
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.