Sensing coil geometry for metal object detection in predetermined spaces with increased sensitivity

A coil and object technology, applied in the field of sensing coil geometry, can solve the problems of sensing coil sensitivity reduction, sensing coil interference, etc.
CN107223300BActive Publication Date: 2021-04-06WITRICITY CORP
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
WITRICITY CORP
Publication Date
2021-04-06

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Abstract

The present disclosure provides systems, methods and devices for detecting the presence of objects. In one aspect, an apparatus for detecting the presence of an object is provided. The device includes a sensing coil formed from a conductor having a predetermined shape configured to attenuate a current induced in the conductor by an external time-varying magnetic field. The sensing coil has electrical characteristics that vary according to the presence of an object. The device includes a detection circuit coupled to the sensing coil and configured to detect the presence of the object in response to detecting a difference between a measured value of the electrical property and a reference value of the electrical property. In the absence of an object above at least a portion of the sensing coil, the reference value of the electrical characteristic is substantially the same as the measured value of the electrical characteristic.
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Description

technical field

[0001] The present disclosure relates generally to wireless power transfer, and more particularly to sensing coil geometry with improved sensitivity for metal object detection in a predetermined space. Background technique

[0002] Wireless charging systems are capable of transferring power in free space, for example, by wireless magnetic fields, for charging electric vehicles. However, the wireless magnetic field may induce eddy currents in any metallic objects located within a predetermined space near the wireless charging system. This eddy current causes metallic objects to heat up and can damage components of the wireless charging system. The presence of such metallic objects can be determined using a sensor system including multiple sensing coils, thereby reducing or interrupting wireless power transfer accordingly. However, the sensitivity of conventional square or rectangular sensing coils is reduced when such a metallic object is located approximate...

Claims

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