Metal foreign matter detection circuit and non-blind area wireless charging metal foreign matter detection system

Abstract

The invention provides a metal foreign matter detection circuit and a non-blind area wireless charging metal foreign matter detection system, the circuit comprises four blind area detection coils distributed according to four quadrant planes, and the first and third quadrant blind area detection coils are connected to a first differential foreign matter detection circuit; the second quadrant blind area detection coil and the fourth quadrant blind area detection coil are connected to the second differential foreign matter detection circuit, the two differential foreign matter detection circuits are each internally provided with a differential amplification circuit, and one blind area detection coil is connected to one input end of the differential amplification circuit through an overcompensation signal collection channel. The other blind area detection coil is connected to the other input end of the differential amplification circuit through an under-compensation signal acquisition channel, and when the absolute value of the output voltage of the first differential foreign matter detection circuit or / and the second differential foreign matter detection circuit is higher than a preset threshold value, it is judged that metal foreign matter exists. The wireless charging system has the advantages that the whole area on the upper portion of the transmitting coil of the wireless charging system can be sensitively detected, and no detection blind area exists.

Description

technical field [0001] The present invention relates to foreign object detection technology in the technical field of wireless charging, in particular to a metal foreign object detection circuit and a wireless charging metal foreign object detection system without blind spots. Background technique [0002] When the electric vehicle wireless charging system is working, since there is a strong electromagnetic coupling area between the transmitting coil and the receiving coil, any metal foreign matter entering or approaching the coupling area will change the electrical parameters of the coupling mechanism, causing the system to deviate from the normal operating point and affecting its output power and transmission efficiency. Due to the eddy current effect, the metal foreign body will cause its own temperature to rise and cause fire and other accidents, which poses a huge safety hazard. [0003] Although the existing metal foreign object detection scheme for wireless charging ...

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Problems solved by technology

[0002] When the electric vehicle wireless charging system is working, since there is a strong electromagnetic coupling area between the transmitting coil and the receiving coil, any metal foreign matter entering or approaching the coupling area will change the electrical parameters of the coupling mechanism, causing the system to deviate from the normal operating point and affecting its Output Power and Transmission Efficiency

Due to the eddy current effect, the metal foreign body will cause its own temperature to rise and cause fire and other accidents, which poses a huge safety hazard

[0003] Although the existing metal foreign object detection scheme for wireless charging systems based on detection coils can detect metal foreign objects more sensitively, the existence of detection blind spots will lead to certain safety hazards in this method, and the blind spot elimination method with superimposed detection coils has become a Doubling the cost of the system, so a new way is needed to eliminate the blind area of ​​the metal foreign object detection system at a lower cost

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