WO2017063135A1

WO2017063135A1 - Energy transmission optimization of foreign object monitoring and magnetic saturation

Info

Publication number: WO2017063135A1
Application number: PCT/CN2015/091817
Authority: WO
Inventors: 于保华; 胡颖
Original assignee: 苏州宝润电子科技有限公司
Priority date: 2015-10-13
Filing date: 2015-10-13
Publication date: 2017-04-20

Abstract

When a transmitting end mistakenly considers a foreign object as a receiving end, not only an energy loss but also security issues, such as an explosion caused by an excessive instantaneous current, are caused. Therefore, the foreign object, which is not removed through monitoring, may interfere with the normal operation of a wireless charging system. Magnetic saturation is a physical property of magnetic materials, and the voltammetric behavior thereof may cause confusion in a foreign object monitoring process and produce an energy loss. Provided is a method for monitoring a foreign object in a wireless charging process, thus a loss caused by the foreign object and magnetic saturation is avoided, and energy transmission of a wireless charging system is optimized.

Description

Foreign body monitoring and magnetic saturation energy transfer optimization

Technology field: Foreign Object Detection (FOD), which monitors foreign objects (mostly metals) that cannot be inductively charged during wireless charging, stops energy transmission and avoids negative effects such as overheating of objects. Magnetic saturation is a physical property of a magnetic material, which means that the magnetic flux passing through the magnetically permeable material cannot be infinitely increased due to the limitation of the physical structure, thereby maintaining a certain number of states. Wireless charging technology, also known as non-contact inductive charging, is derived from wireless power transmission technology, using near-field sensing, inductive coupling, and energy is transmitted from a power supply device to a powered device that uses the received Energy charges the battery and at the same time serves itself. There are three mainstream wireless charging standards: Qi standard, PMA standard, and A4WP standard. FOD and magnetic saturation are likely to occur in all of the above three wireless charging standards. The present invention is directed to monitoring and eliminating foreign matter and magnetic saturation, and is applicable to the Qi standard and the PMA standard.

BACKGROUND OF THE INVENTION: Based on a wireless charging system framework, the process of transmitting power by two devices (generally referred to as an energy transmitting end and an energy receiving end) does not require the passage of any physically present tangible wires. When the transmitting end misinterprets the foreign object as the receiving end, it not only generates energy loss but also may cause a safety problem such as an explosion caused by an excessive current. Therefore, the undetected foreign matter may interfere with the normal operation of the wireless charging system. Magnetic saturation is a physical property of magnetic materials, and its volt-ampere performance can cause confusion to the foreign matter monitoring process and generate energy loss. The invention aims to monitor foreign matter during wireless charging, avoid loss caused by foreign matter and magnetic saturation, and optimize energy transmission of the wireless charging system.

SUMMARY OF THE INVENTION: Let us first understand the wireless charging system framework. Figure 1 depicts a system framework for wireless charging of a mobile terminal through a charging base. The mobile terminal can be a portable electronic product that can be wirelessly charged by an ordinary mobile phone, a smart phone, a handheld computer, a pad, or the like. When the charging base detects the mobile terminal (the distance of the mobile terminal from the charging base is less than 1 cm), the energy conversion unit of the transmitting end supplies energy to the transmitting coil to generate a magnetic field. At the receiving end, the magnetic field energy is received by the receiving coil and converted into a current, while the receiving energy unit supplies power to the load of the mobile terminal. Both the transmitter and receiver have a communication and control unit that senses and manages the wireless charging process.

In the wireless charging process, the charging base can calculate the transmission energy (P=I*V) of the transmitting end by detecting the transmitting voltage and the emitting current of the transmitting end (ie, the voltage across the transmitting coil and the current flowing through the transmitting coil). Similarly, the mobile terminal can detect the receiving voltage and the receiving current of the receiving end (ie, the voltage across the receiving coil and the current flowing through the transmitting coil) and provide it to the transmitting end, and then the charging base will calculate the transmission of the receiving end by the communication and control unit. Energy (P = I * V), and calculate the energy loss Loss is the transmission energy of the transmitting end minus the transmission energy of the receiving end (Loss = P _{TX -} P _RX ).

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further described below in conjunction with the drawings and embodiments.

Figure 1 is a wireless charging system frame diagram

Figure 2 is the energy transfer optimization process

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The flow of the present invention for monitoring foreign matter and avoiding magnetic saturation to optimize energy transfer is as shown in FIG. 2:

W0.Ping - The transmitting end sends a Ping command every few seconds to determine if an object is within the chargeable range.

W1. Turn on the transmitter - When the result of W0 is YES, wake up the transmitter to start working.

W2.W9. Read the transmitter voltage V _TX , current I _TX -- read the transmitter voltage and current, calculate the transmitter transmission energy P _TX = I _TX * V _TX .

W3.W10. Read the receiving terminal voltage I _RX , current I _RX -- read the receiving terminal voltage and current, calculate the receiving end transmission energy P _RX =I _RX *V _RX .

W4.W11. Calculate the new loss Lossnew - calculate the new loss Lossnew=P _TX -P _RX .

W5. Determine whether the loss exceeds the threshold - different wireless charging standards will have different thresholds, such as 0.25W for the threshold of the Qi system.

W6. Continue charging - When the judgment result of W5 is NO, the wireless charging system works normally, and the transmitting end will continue to charge the receiving end for a period of time, and then continue to step W2.

W7. The storage loss value is Loss—when the judgment result of W5 is YES, it means that it may be the full power of the receiving end, the foreign object or the magnetic saturation state of the object. Next, the result of the W4 calculation is stored in the variable Loss. , that is, Loss=Lossnew.

. W8 decrease in emission current I _TX end fixed ratio - the transmitter current I _TX fixed value needs to be reduced, i.e. decreases according to a fixed ratio, for example, a new I _TX I _TX reduced to the original 90% or 80% of the original I _TX , or less than 100% of the original I _TX any percentage of the case.

W12. Calculate △Loss=Loss-Lossnew—calculate the change in energy loss according to the formula.

W13. △Loss is proportional to the emitter current I _TX - determine whether the change in energy loss ΔLoss is proportional to the change in the emitter current I _TX , for example, if I _{TX is} reduced to 90% of I _TX , ie ΔI _TX It is 10%, then it is necessary to calculate whether the proportion of Loss in W1 in W6 is also nearly 10%.

W14. Exit the magnetic saturation state and continue charging. When the judgment result of W13 is NO, it indicates that it is in the magnetic saturation state, and continues to charge after exiting the magnetic saturation state.

W15.FOD is determined to stop charging the foreign object - when the judgment result of W13 is YES, the object is a foreign object (it can also be regarded as a foreign object when the receiving end is full of electricity), and the charging is stopped.

Claims

It is determined whether the wireless charging system is in a normal working state according to whether the loss of energy transmission during the wireless charging process exceeds a threshold.
Based on the requirements of claim 1, the magnetic saturation is excluded according to the criteria for determining the state of magnetic saturation, and FOD foreign matter monitoring is performed.