Wireless Power Foreign Object Detection via Adaptive Resonance Modes
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Solution Overview
Problem
Existing wireless power transmission systems face challenges in accurately detecting metallic foreign objects due to changes in antenna coil characteristics caused by alternating magnetic fields, leading to potential errors in foreign object detection.
Innovation Solution
A metallic foreign object detector is introduced, utilizing a plurality of antenna coils and capacitors to form resonance circuits, with a detection part that selects detection modes based on power feeding state and coil position, employing integral value and vibration time length analysis to enhance detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single detection mode is used for foreign object detection, then the device complexity is reduced, but the detection accuracy deteriorates under varying power feeding states
Solution Approach 1:
The patent implements multiple detection modes (first detection mode using integral value, second detection mode using vibration time length) that can be dynamically selected based on the power feeding state. The control circuit determines whether the system is in power feeding or non-power-feeding state and switches between detection modes accordingly, allowing the detection characteristics to adapt to different operational conditions and maintain high accuracy without requiring all detection mechanisms to be simultaneously active
Solution Approach 2:
The patent changes the detection parameters based on the power feeding state. In the first detection mode, the integral value of the vibration signal is used as the detection parameter. In the second detection mode, the vibration time length (period) is used as the detection parameter. This parameter switching allows the system to maintain high detection accuracy under different magnetic field conditions without increasing the fundamental detection mechanism complexity
2Productivity
If detection is performed during power feeding, then productivity is maintained, but detection accuracy deteriorates due to alternating magnetic field interference
Solution Approach 1:
The patent performs foreign object detection at two distinct timing points: before power feeding begins (non-power-feeding state detection) and during power feeding operation (power-feeding state detection). By conducting detection at these different stages with appropriate detection modes for each state, the system ensures continuous productivity while maintaining detection accuracy throughout the power transmission process
Solution Approach 2:
The system implements periodic foreign object detection that alternates between different detection modes based on the power feeding cycle. The control circuit periodically switches between first detection mode (integral value-based) and second detection mode (vibration time length-based) according to whether the system is in power feeding or non-power-feeding state, ensuring continuous monitoring without interruption to power transmission
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 configuration achieves high detection accuracy for metallic foreign objects irrespective of the power feeding state, reducing erroneous detections by adapting detection modes to the influence of alternating magnetic fields.
Implementation Method 1
a plurality of antenna coils L3 that generate a vibration signal by receiving a magnetic field
Implementation Method 2
one or more capacitors C3 that constitute a resonance circuit together with each of the plurality of antenna coils L3
Implementation Method 3
When a metallic foreign object enters between the magnetically coupled feeding coil and receiving coil, an eddy current flows in the metallic foreign object by magnetic flux, resulting in heat generation in the metallic foreign object
Data Source
AI summary
A metallic foreign object detector, used in a wireless power transmission system that transmits power using an alternating magnetic field, includes antenna coils that generate a vibration signal by receiving a magnetic field or current, one or more capacitors that constitute a resonance circuit together with each of the antenna coils, and a detection part that detects a metallic foreign object by sequentially using the antenna coils. The detection part has detection modes that detect the presence/absence of the metallic foreign object based on changes in mutually different characteristics of the resonance circuit. The detection part selects one mode from the detection modes in accordance with at least one of the power feeding state of the wireless power transmission system and the position of each of the plurality of antenna coils and performs the detection of the metallic foreign object in the selected detection mode.