Foreign body detection method and system based on impedance characteristic

Abstract

The invention provides a foreign body detection method and system based on an impedance characteristic. The method comprises the steps that a detection coil is laid in an area to be detected, wherein the detection coil is connected with a capacitor element to form a resonant circuit, and a high frequency carrier signal is loaded on the resonant circuit; a resonant current signal on the resonant circuit is collected; other induction signals outside the frequency band of the high frequency carrier signal are filtered out; and finally, amplitude and phase analysis is carried out on the filtered resonant current signal to determine whether a foreign body is in the area to be detected. The method has the advantages that the impedance change of the detection coil is correspondingly acquired by detecting the change of the phase and amplitude of the resonant current signal, so as to judge whether a foreign matter exists. The method has the advantages of low cost and good effect. The original system is changed less. Especially for a wireless power transmission system, without affecting the efficiency of the original system, the method and system can be well adapted to foreign body detection in a variety of magnetic fields to improve the safety of the wireless power transmission system.

Description

technical field [0001] The present invention relates to foreign matter detection technology, in particular to a foreign matter detection method and system based on impedance characteristics, which are mainly used in wireless power transmission systems. Background technique [0002] Wireless Power Transfer Technology (Wireless Power Transfer Technology) generally refers to a new power supply mode that transmits power from the source level to the power receiving level in the form of electrical isolation by means of an energy transfer medium that exists in the physical space. It solves the problem of convenient and safe access to the power supply, and solves the problems of plug-in sparks, carbon deposits, difficult maintenance, and easy wear caused by the traditional direct contact power transmission mode that relies on electrical conductors for direct physical contact. Potential safety hazards in using electricity in special environments. Wireless power transmission technolo...

AI Technical Summary

Problems solved by technology

[0004] In the prior art, Chinese patent 201410308045.5 discloses a method for detecting foreign objects in wireless charging. The method is to judge whether there are foreign objects by testing the energy transmission loss during the energy transmission process. As mentioned above, foreign objects are detected during the energy transmission process. It is usually too late to detect, especially the presence of metal foreign objects, which can quickly heat up and cause safety accidents

In addition, most of the existing foreign object detection methods can only detect metal foreign objects, and their detection accuracy is low for the existence of organisms

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