Foreign Object Detection Coil Layout to Reduce Induced Voltage
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Solution Overview
Problem
Existing foreign object detection devices in wireless power transfer systems face issues with induced voltage due to magnetic flux, which can damage peripheral circuits, especially when connecting lines form large loop circuits.
Innovation Solution
A foreign object detection device with coils on a substrate that generates a vibration signal, using a first and second connecting line to connect coil terminals to a detector, with these lines extending in substantially identical paths to minimize the loop circuit opening and reduce induced voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If connecting lines are arranged to cover the power transmission coil area for foreign object detection, then detection coverage is improved, but induced voltage increases causing circuit damage
Solution Approach 1:
The connecting lines are arranged asymmetrically with respect to the magnetic flux paths, specifically routing them along the outer periphery of the power transmission coil rather than through its center. This asymmetric arrangement minimizes the magnetic flux interlinking with the connecting lines, reducing induced voltage while preserving foreign object detection capability across the coil area
Solution Approach 2:
The connecting lines are routed along the outer periphery of the power transmission coil, utilizing the radial dimension of the coil structure. By positioning connecting lines at the outer edge rather than allowing them to traverse the central area, the design reduces magnetic flux exposure while maintaining detection coverage through strategic placement of detection coils at multiple positions
2Reliability
If connecting lines form loop circuits to connect coil terminals, then electrical connection is achieved, but magnetic flux interlinking increases causing high induced voltage
Solution Approach 1:
The harmful function of the connecting lines forming large loop circuits that intercept magnetic flux is extracted and eliminated. Instead of allowing connecting lines to form loops across the coil area, they are routed along the outer periphery in a linear fashion that minimizes flux interlinking, separating the electrical connection function from the harmful flux-intercepting loop structure
Solution Approach 2:
The arrangement of connecting lines along the outer periphery, which initially might seem to reduce detection coverage, actually benefits the system by minimizing induced voltage. The connecting lines serve dual purposes: providing reliable electrical connection while simultaneously acting as a protective measure against high induced voltage by avoiding the high-flux central region
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 reduces the induced voltage and prevents damage to circuits by minimizing the magnetic flux interlinking with the loop circuit, ensuring reliable foreign object detection and safe power transfer.
Implementation Method 1
a plurality of coils mounted on a substrate to be excited and thus generate a vibration signal
Implementation Method 2
a detector to detect the existence of a foreign object on the basis of the vibration signal
Implementation Method 3
If the connecting lines configure a large loop circuit, the alternating magnetic flux for power transmission generated at the power transmission coil may induce a high electromotive force in the connecting lines
Data Source
AI summary
A foreign object detection device includes a plurality of coils (240) each including a first conductive pattern mounted on one surface of a detection coil substrate (220) to be excited and thus generate a vibration signal, a detector (26) to detect the existence of a foreign object on the basis of the vibration signal, a first connecting line (230) to connect one terminals (T1) of the individual coils (240) to the detector (26), and a second connecting line (232) to connect the other terminals (T2) of the individual coils (240) to the detector (26). The first connecting line (230) and the second connecting line (232) extend in substantially identical paths in at least segments mounted on the detection coil substrate (220).