Wireless Power Receiver Foreign Object Detection via Q-Factor Calibration
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Solution Overview
Problem
Existing wireless power transmission systems 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 cause power waste and damage to the transmitter and receiver.
Innovation Solution
A method for detecting foreign objects using a wireless power receiver that dynamically calibrates a measured quality factor value based on the shift of a current peak frequency from a reference peak frequency, calculates a quality factor slope, and compares it with predetermined thresholds to accurately identify the presence of foreign objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless power transmission is performed using electromagnetic induction or resonance, then power can be transferred wirelessly to devices, but foreign objects in the charging area may be heated due to induced electromagnetic signals
Solution Approach 1:
The system performs foreign object detection before initiating full wireless power transmission. By measuring quality factor values at the actual operating frequency (which may differ from reference frequency due to drift) and comparing against threshold values, the system identifies foreign objects in advance and prevents power transmission that would cause heating, thus eliminating the harmful effect before it occurs.
Solution Approach 2:
The system continuously monitors the actual operating frequency and adjusts the quality factor measurement accordingly. By using feedback from frequency measurements to select appropriate threshold values and measurement frequencies, the system maintains accurate foreign object detection despite frequency variations, ensuring safe operation while enabling wireless power transfer.
2Productivity
If the charging area temperature increases due to foreign object presence, then power transmission efficiency decreases and energy is wasted, but continuing transmission causes overheating and potential damage
Solution Approach 1:
The system performs quality factor measurements at the actual operating frequency before full power transmission begins. This preliminary detection identifies foreign objects that would cause energy waste through heating, allowing the system to prevent inefficient power transmission and avoid both energy loss and potential damage.
3Measurement precision
If quality factor measurement is performed at reference operating frequency, then foreign object detection can be implemented, but frequency variations cause inaccurate detection results
Solution Approach 1:
The system dynamically adapts the quality factor measurement frequency to match the actual operating frequency, which may differ from the reference frequency due to drift or environmental factors. By making the measurement frequency dynamic rather than fixed, the system maintains measurement precision across varying operating conditions while preserving adaptability to different scenarios.
Solution Approach 2:
The system changes the measurement parameters (frequency and threshold values) based on the actual operating conditions. By adjusting the quality factor measurement frequency to match the actual operating frequency and selecting appropriate threshold values based on frequency measurements, the system maintains accurate foreign object detection despite frequency variations, resolving the contradiction between precision and adaptability.
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 by accurately identifying their presence, thereby improving system safety and efficiency.
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
The electromagnetic resonance method uses an electric field or a magnetic field instead of using electromagnetic waves or current
Implementation Method 3
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
A wireless power receiver (20) with a a wireless communication unit configured to communicate with a wireless power transmitter (10); a memory configured to store reference values including a reference quality factor and a reference frequency; a controller configured to: generate first and second foreign object status packets including the reference quality factor and the reference frequency,