Foreign Object Detection in Wireless Power Transfer Systems
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Solution Overview
Problem
Wireless power transfer systems face inefficiencies and potential foreign object detection failures due to early Q-factor measurements when devices are not in close proximity, leading to erroneous enablement of power transfer despite the presence of foreign objects.
Innovation Solution
Implementing a method that involves taking a plurality of Q-factor or self-resonant frequency measurements at different times, processing these measurements to determine a minimum, average, or median value, and using this result to decide whether to enable or disable wireless power transfer, while also considering convergence and discarding erroneous measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Q-factor measurements are performed early when devices are not in close proximity, then the system can quickly determine whether to enable power transfer, but the measurements may be erroneous leading to false enablement despite foreign objects being present
Solution Approach 1:
The system performs multiple preliminary Q-factor measurements at different times before finalizing the foreign object detection result. By taking measurements early and processing them through convergence checking, the system prepares accurate detection data in advance without rushing to a premature conclusion, thus resolving the conflict between quick determination and accurate detection.
Solution Approach 2:
The system implements a feedback mechanism where multiple FOD measurements are taken and processed to determine convergence. The measurements are continuously refined and compared, with the process repeating until convergence is achieved or a maximum number of iterations is reached. This feedback loop ensures reliable detection while maintaining efficient operation.
2Reliability
If multiple FOD measurements are taken and processed to ensure accurate detection, then reliability of foreign object detection is improved, but the time and complexity of the detection process increases
Solution Approach 1:
The system uses a universal processing approach that handles both convergence and non-convergence cases through the same measurement framework. The same measurement and processing routine serves multiple purposes: determining foreign objects, checking convergence, and preparing for power transfer enablement, thus reducing overall time loss despite multiple measurements.
Solution Approach 2:
The system dynamically adjusts the number of measurements and processing depth based on convergence criteria. When measurements converge quickly, fewer iterations are needed, reducing time loss. When convergence is slow or foreign objects are detected, the system appropriately increases measurements to maintain reliability, optimizing the balance between time and accuracy.
3Measurement precision
If the system processes FOD measurements to determine convergence and discard erroneous measurements, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The measurement processing system is self-regulating through automated convergence checking and iterative refinement. The system automatically determines when measurements have converged or when foreign objects are detected, eliminating the need for complex external control mechanisms. This self-service approach improves precision while keeping device complexity manageable.
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 ensures reliable foreign object detection by avoiding early measurements and ensuring accurate determination of wireless power transfer enablement, thereby preventing power transfer when foreign objects are present.
Implementation Method 1
The plurality of FOD measurements may be Q-factor measurements or self-resonant frequency measurements
Implementation Method 2
The plurality of FOD measurements may be Q-factor measurements or self-resonant frequency measurements
Implementation Method 3
magnetic induction (MI) systems
Implementation Method 4
magnetic resonance (MR) systems
Data Source
Figure 1A~1B
Figure 2
Figure 3A
AI summary
Methods, apparatus and computer-readable storage media for performing foreign object detection (FOD) in a wireless power transfer system. A plurality of FOD measurements may be performed and processed to perform FOD.