Wireless Power Transmitter Foreign Object Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wireless power transfer systems face inefficiencies and accuracy issues in detecting foreign objects, particularly conductive objects, which can significantly degrade power transmission efficiency and cause overheating, due to limitations in measuring the quality factor (Q-factor) without considering variations in resonant frequency and other parameters.
Innovation Solution
A method and controller for wireless power transmitters that measure the Q-factor of the system including the transmitter and receiver, compare it with a reference Q-factor, and adjust the comparison using additional parameters such as inductance ratios and resonant frequencies to improve foreign object detection accuracy, allowing or disallowing power transfer and adjusting power levels accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Q-factor measurement is performed without considering resonant frequency variations, then foreign object detection can be performed, but detection accuracy deteriorates due to parameter variations
Solution Approach 1:
The patent applies parameter changes by measuring multiple system parameters (Q-factor, resonant frequency, inductance) instead of relying on a single Q-factor measurement. The system compares these parameters against reference values to detect foreign objects, accounting for variations in operating conditions that would otherwise degrade detection accuracy.
Solution Approach 2:
The system implements feedback by measuring the actual resonant frequency and inductance of the wireless power transmitter, then using these measurements to adjust or interpret the Q-factor comparison. This feedback loop allows the system to compensate for parameter variations and maintain accurate foreign object detection.
2Measurement precision
If additional parameters (inductance ratios, resonant frequencies) are considered in comparison, then foreign object detection accuracy improves, but system complexity increases
Solution Approach 1:
The patent applies universality by using a multi-functional measurement system that measures Q-factor, resonant frequency, and inductance using the same wireless power transmitter circuitry. These multiple measurements serve both the primary function of power transfer characterization and the secondary function of accurate foreign object detection, eliminating the need for separate dedicated sensors.
Solution Approach 2:
The system merges the measurement of multiple parameters (Q-factor, resonant frequency, inductance) into a unified foreign object detection process. Instead of treating these as separate measurements requiring separate processing chains, the patent combines them into a single comparative analysis against reference values, simplifying the overall system architecture.
3Reliability
If foreign object detection is performed using conventional Q-factor measurement, then detection can be implemented, but power transmission efficiency degrades due to false positives or missed detections
Solution Approach 1:
The patent changes the detection parameters from a single Q-factor measurement to a multi-parameter comparison including resonant frequency and inductance. This allows the system to distinguish between legitimate variations in power transfer conditions and actual foreign object presence, reducing false positives that would otherwise cause unnecessary power transfer interruptions.
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
Enhances the accuracy of foreign object detection, preventing power transfer degradation and overheating by accounting for variations in resonant frequency and other parameters, thereby ensuring reliable and efficient wireless power transfer.
Implementation Method 1
magnetic induction (MI) systems
Implementation Method 2
magnetic resonance (MR) systems
Implementation Method 3
measuring Q-factor of a system including the wireless power transmitter and the wireless power receiver
Data Source
AI summary
Foreign object detection for a wireless power transmitter can be performed using a reference Q-factor and measured Q-factor. The reference and measured Q-factors are compared to determine where a foreign object is present. The comparison is adjusted based on one or more additional parameters.