Wireless Power Foreign Object Detection Using Q-Factor and Resonance
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Solution Overview
Problem
Existing wireless power transfer systems face challenges in accurately detecting foreign objects, as techniques relying solely on quality factor (Q-factor) measurements can be inaccurate due to variations in resonant frequency, leading to inefficient power transfer and potential overheating.
Innovation Solution
A method that measures both Q-factor and resonant frequency, calculates a figure of merit (FOM) based on these parameters, and compares it with a reference FOM to determine the presence of foreign objects, allowing for precise foreign object detection and adjusting power transfer accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only Q-factor measurement is used for foreign object detection, then the detection method is simple, but the detection accuracy is low due to resonant frequency variations
Solution Approach 1:
The patent changes the detection parameters from only Q-factor to a combination of Q-factor and resonant frequency measurements. By monitoring both parameters and comparing their changes against threshold values, the system achieves more accurate foreign object detection while accounting for resonant frequency variations that occur during wireless power transfer.
2Ease of operation
If Q-factor measurement is used for foreign object detection, then the implementation is straightforward, but false detection occurs due to frequency variations
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors both Q-factor and resonant frequency, compares the changes against pre-determined threshold values, and adjusts power transfer accordingly. This feedback loop reduces false detections by distinguishing between normal frequency variations and actual foreign object presence.
3Productivity
If foreign object detection is not performed, then power transfer continues without interruption, but power degradation and overheating occur
Solution Approach 1:
The patent performs preliminary foreign object detection by measuring Q-factor and resonant frequency changes before allowing power transfer to continue or increase. By detecting foreign objects in advance through these parameter measurements and comparisons, the system prevents power degradation and overheating while minimizing interruptions to legitimate power transfer operations.
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, improving the efficiency of wireless power transfer by differentiating between wireless power receivers and foreign objects, thereby preventing power degradation and overheating.
Implementation Method 1
magnetic induction (MI) systems
Implementation Method 2
magnetic induction (MI) systems
Implementation Method 3
measuring a first parameter corresponding to Q-factor and a second parameter corresponding to resonant frequency
Data Source
AI summary
Foreign object detection for a wireless power transmitter can be performed using a reference Q-factor and reference frequency for a wireless power receiver. A figure of merit may be calculated using the reference Q-factor and reference frequency. A Q-factor and resonant frequency may be measured, and a measurement figure of merit can be calculated. The figures of merit can be compared to determine where a foreign object is present.