Wireless charging device and metal foreign substance detection method thereof

Abstract

The invention proposes a metal foreign substance detection method based on a quality factor. The method is applicable to a wireless charging device of a magnetic induction technology. The device comprises an emission end and a receiving end. When a metal foreign substance exists between a primary coil of the emission end and a secondary coil of the receiving end, the metal foreign substance will be heated by an eddy current effect to cause a serious safety potential. The detection method proposed by the invention is used for detecting the metal foreign substance, and power transmission can be automatically ended. The core content lies that the quality factor of the primary coil of the emission end is detected, whether the metal foreign substance exists is judged by comparing a detection value and a setting threshold value, the fact that the metal foreign substance exists is judged if the detection value is smaller than the setting threshold value, the emission end prompts warning, and the power transmission is ended.

Description

technical field [0001] The invention relates to an electromagnetic induction type wireless charger (QI standard), in particular to a wireless charging device and a method for detecting metal foreign objects. Background technique [0002] The wireless charging device adopts magnetic induction technology, and the implementation standard is compatible with the Qi standard of the International Wireless Power Consortium (WPC). The primary coil at the transmitter end and the secondary coil at the receiver end of the wireless charging device transmit power and information through electromagnetic induction. When there is a metal foreign body between the two coils, a large amount of heat will be generated on the metal foreign body due to the eddy current effect, and there is a serious safety hazard. Therefore, the metal foreign body detection is an essential function of the wireless charging device. [0003] At present, the detection of metal foreign objects in wireless charging dev...

AI Technical Summary

Problems solved by technology

The reasons for the above problems are more complicated. On the one hand, the power loss method on the inverter bridge and the transmitting coil cannot be obtained by direct measurement. Therefore, the calculation error formed when calculating the power loss leads to inaccurate detection of metal foreign objects. ; On the other hand, the threshold setting of the metal foreign object alarm power loss will affect the sensitivity of foreign object detection, and the determination of the optimal power loss threshold is difficult to achieve, and a large number of experiments are needed to accumulate rich experience

[0004] For foreign object detection of wireless charging devices, the power loss method on the market cannot directly measure the power loss on the inverter bridge and transmitting coil, so there are calculation errors in the power loss calculation process, which leads to the sensitivity of foreign object detection Difficult to adjust, false positives, missed negatives and other issues

Images