Wireless Power FOD Coils for Small Foreign Object Detection
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Solution Overview
Problem
Current wireless power transmission devices face difficulties in detecting metallic foreign objects, especially when their size is smaller than the transmission antenna, as the measurement of electromagnetic wave parameters is susceptible to transmission distance and efficiency, leading to hazardous overheating.
Innovation Solution
The implementation of multiple Foreign Object Detection (FOD) coils mounted on an insulating substrate, connected in series and spaced apart, with a radiation pattern overlapping the transmission antenna's radiation, and a controller that uses feedback detection circuits and reference voltage generation to determine the presence of metallic foreign objects, allowing for immediate shutdown of radiation to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electromagnetic wave parameters are measured to detect metallic foreign objects, then detection capability is provided, but detection precision deteriorates when foreign object size is smaller than transmission antenna
Solution Approach 1:
The patent divides the detection system into multiple FOD coils (first FOD coil and second FOD coil) with different configurations. Each coil is designed to detect foreign objects in specific spatial zones, enabling segmented coverage of the electromagnetic field region. This segmentation allows detection of small foreign objects that would be missed by a single large antenna measurement approach.
Solution Approach 2:
The patent introduces FOD coils as intermediary detection elements between the transmission antenna and the foreign objects. These coils act as sensitive mediators that can detect changes in electromagnetic field caused by small foreign objects, translating subtle field variations into detectable signals that improve measurement precision.
2Length of stationary object
If transmission distance of electromagnetic waves increases, then power transmission range is improved, but detection reliability of foreign objects deteriorates
Solution Approach 1:
The patent applies local quality by positioning FOD coils at specific locations where electromagnetic field strength is sufficient for reliable detection. The first and second FOD coils are strategically placed to cover different spatial zones, ensuring that each location has optimized detection capability. This local optimization maintains detection reliability across varying transmission distances without requiring uniform system redesign.
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
Effectively detects metallic foreign objects smaller than the transmission antenna, preventing overheating by ensuring a uniform electromagnetic field sensing capability and allowing for timely intervention to stop radiation when a foreign object is detected.
Implementation Method 1
Each FOD coil has three coil unit connected in series to and spaced apart from one another. A radiation pattern of the transmission antenna overlaps a sensing range of the FOD coils
Implementation Method 2
When metallic foreign object enters a range of the electromagnetic waves generated by the wireless power transmission device, the metallic foreign object generates high heat under the effect of electromagnetic field
Data Source
AI summary
A wireless power transmission device radiates electromagnetic waves through a transmission antenna and generates multiple sensed signals by using multiple foreign object detection (FOD) coils for detecting metallic foreign object to sense the electromagnetic waves. Each FOD coil has three coil units connected in series to and spaced apart from one another. The radiation pattern of the transmission antenna overlaps a sensing range of the FOD coils. A controller of the wireless power transmission device determines if any metallic foreign object enters the radiation range of the transmission antenna according to a reference voltage signal and sensed signals of the cells, and stops the generation of electromagnetic waves when determining entry of metallic foreign object into the radiation range to avoid the metallic foreign object to be heated by the electromagnetic waves.