Foreign Object Detection in Wireless Power Transfer Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless power transfer systems, the varying shape, size, and attachment height of coils in movable objects can lead to incorrect detection of foreign objects within or outside the magnetic field generation region, causing unnecessary interruptions in power transfer.
Innovation Solution
A foreign object detection device that identifies the magnetic field generation region based on coil device information and position detection, using a light projecting and receiving unit to distinguish between foreign objects within and outside the region, reducing unnecessary power transfer interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If foreign object detection is performed in the entire detection region without distinguishing magnetic field generation region, then all foreign objects are detected, but wireless power transfer is stopped even when foreign objects are outside the magnetic field generation region
Solution Approach 1:
The detection region is segmented into two distinct zones: the magnetic field generation region (first detection region) where foreign objects affect power transfer, and the region outside it (second detection region) where foreign objects do not affect power transfer. This segmentation allows selective detection and response based on foreign object location, preventing unnecessary interruptions.
Solution Approach 2:
Different detection strategies are applied to different regions: the first detection region (magnetic field generation region) uses sensitive detection to identify foreign objects that would interfere with power transfer, while the second detection region uses less sensitive detection or no detection, since foreign objects there do not impact power transfer. This local differentiation resolves the contradiction between comprehensive detection and maintaining power transfer continuity.
2Area of stationary object
If the detection region is expanded to cover all areas between coil devices, then detection coverage is improved, but the likelihood of unnecessary power transfer interruptions increases
Solution Approach 1:
The expanded detection area is divided into the first detection region (corresponding to the magnetic field generation region) and the second detection region (areas outside the magnetic field generation region). By segmenting the coverage area, the system maintains comprehensive monitoring while avoiding false alarms from non-critical regions.
Solution Approach 2:
The system applies different detection thresholds and response strategies to different areas within the detection region. The first detection region has high detection sensitivity with strict response criteria, while the second detection region has lower sensitivity or no response requirements, optimizing both coverage and efficiency.
3Measurement precision
If foreign object detection sensitivity is increased to detect all objects, then detection capability is improved, but false detection of non-harmful objects increases
Solution Approach 1:
The detection system is segmented into two independent detection channels: one for the first detection region (magnetic field generation region) with high sensitivity, and another for the second detection region with lower sensitivity or no detection. This segmentation allows high sensitivity where needed without generating false alarms from non-critical areas.
Solution Approach 2:
Different detection sensitivities and criteria are applied locally to different regions. The first detection region uses high sensitivity detection with criteria specifically tuned to identify foreign objects that would interfere with magnetic field generation, while the second detection region uses lower sensitivity or different criteria, reducing false detections of non-harmful objects.
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
Accurate identification of foreign objects within the magnetic field generation region minimizes unnecessary power transfer interruptions, ensuring efficient wireless power transfer by differentiating between objects affecting and not affecting the magnetic field.
Implementation Method 1
a light projecting unit that projects light, a light receiving unit that receives the light projected by the light projecting unit
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
A foreign object detection device for a wireless power transfer system includes a storage unit that stores first coil device information including a shape and a size of a first coil facing surface, a height position from the reference surface, and a height position of a first device facing surface; an information acquiring unit that acquires second coil device information including a shape, a size, and a height position of a second coil facing surface, and a height position of a second device facing surface; a region identifying unit that identifies a magnetic field generation region generated between the first device facing surface and the second device facing surface during power feeding, based on the first coil device information and the second coil device information; and a foreign object detection unit that detects the presence or absence of a foreign object within the identified magnetic field generation region.