KR102573342B1 - Foreign Object Detection Method and Apparatus and System therefor - Google Patents

Abstract

The present invention relates to a method for detecting a foreign substance and an apparatus and system therefor, and the method for detecting a foreign substance in a wireless power transmitter includes measuring the intensity of current input to an inverter in a ping step and receiving a packet including a receiver type identifier. The method may include determining a foreign material detection threshold value corresponding to the receiver type identifier and determining whether a foreign material exists by comparing the measured current intensity with the threshold value. Therefore, the present invention has the advantage of being able to detect FO more effectively.

Description

Foreign object detection method and apparatus and system therefor

The present invention relates to wireless power transmission technology, and more particularly, to a method for detecting a foreign substance in a wireless charging system and an apparatus and system therefor.

Recently, as information and communication technology develops rapidly, a ubiquitous society based on information and communication technology has been established.

In order to access information and communication devices anytime, anywhere, computers with communication functions in all facilities of society. Recently, as information and communication technology develops rapidly, a ubiquitous society based on information and communication technology is being established.

In order to access information and communication devices anytime and anywhere, sensors embedded with computer chips with communication functions must be installed in all social facilities. Therefore, the problem of supplying power to these devices or sensors is becoming a new challenge. In addition, as the types of portable devices such as mobile phones as well as Bluetooth handsets and music players such as iPods are rapidly increasing, the task of charging the batteries is requiring time and effort from users. As a method of solving this problem, a wireless power transfer technology has recently been attracting attention.

Wireless power transmission or wireless energy transfer is a technology that transmits electrical energy wirelessly from a transmitter to a receiver using the induction principle of a magnetic field. Electric motors or transformers using the principle of electromagnetic induction have already been used in the 1800s. After that, a method of transmitting electric energy by radiating electromagnetic waves such as high frequency, microwave, and laser was also attempted. In fact, electric toothbrushes and some cordless razors that we commonly use are charged using the principle of electromagnetic induction.

Until now, energy transfer methods using wireless can be largely classified into magnetic induction methods, magnetic resonance (Electromagnetic Resonance) methods, and RF transmission methods using short-wavelength radio frequencies.

The magnetic induction method is a technology that uses a phenomenon that when two coils are placed adjacent to each other and current is passed through one coil, the magnetic flux generated at this time causes an electromotive force in the other coil. It is rapidly commercialized around small devices such as mobile phones. is in progress The magnetic induction method can transmit power of up to hundreds of kilowatts (kW) and has high efficiency, but the maximum transmission distance is less than 1 cm (cm), so it generally has a disadvantage that it must be adjacent to a charger or the floor.

The magnetic resonance method is characterized by using an electric field or a magnetic field instead of using electromagnetic waves or current. The magnetic resonance method has the advantage that it is safe for other electronic devices or the human body because it is hardly affected by electromagnetic problems. On the other hand, it can be used only in a limited distance and space and has a disadvantage that the energy transfer efficiency is somewhat low.

The short-wavelength wireless power transmission scheme—briefly, the RF transmission scheme—takes advantage of the fact that energy can be directly transmitted and received in the form of radio waves. This technology is an RF wireless power transmission method using a rectenna, and the rectenna is a compound word of an antenna and a rectifier, and means an element that directly converts RF power into DC power. That is, the RF method is a technology that converts AC radio waves into DC and uses them. As efficiency has recently improved, research on commercialization has been actively conducted.

Wireless power transmission technology can be used not only in mobile, but also in various industries such as IT, railway, and home appliance industries.

When a conductor other than a wireless power receiver, that is, a foreign object (FO) exists in the wireless charging area, the electromagnetic signal transmitted from the wireless power transmitter is induced in the FO, and the temperature may rise. For example, FO may include coins, clips, pins, ballpoint pens, and the like.

If the FO exists between the wireless power receiver and the wireless power transmitter, the wireless charging efficiency may significantly decrease and the temperature of the wireless power receiver and the wireless power transmitter may increase together due to the temperature increase around the FO. If the FO located in the charging area is not removed, power is wasted and overheating may cause damage to the wireless power transmitter and the wireless power receiver.

Therefore, detecting the FO located in the charging area has emerged as an important issue in the field of wireless charging technology.

The present invention was conceived to solve the above-described problems of the prior art, and an object of the present invention is to provide a method for detecting foreign matter for wireless charging and a device and system therefor.

Another object of the present invention is to provide a wireless power transmission device capable of detecting a foreign substance based on a change in inverter input current measured in a ping step.

Another object of the present invention is to provide a foreign matter detection method capable of more accurate foreign matter detection by determining a current change threshold or threshold ratio for dynamically determining the presence or absence of a foreign matter based on a receiver type, and an apparatus and system therefor. .

The technical problems to be achieved in the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below. You will be able to.

The present invention can provide a foreign material detection method and an apparatus and system therefor.

A foreign matter detection method in a wireless power transmitter according to an embodiment of the present invention includes measuring the intensity of current input to an inverter in a ping step, receiving a packet including a receiver type identifier, and the receiver type identifier corresponding to each other. The method may include determining a threshold value for detecting a foreign substance, and determining whether a foreign substance exists by comparing the measured current intensity with the threshold value.

For example, the receiver type identifier may be included in a configuration packet and received in the configuration and identification step.

As another example, the receiver type identifier may be included in a Foreign Object Detection (FOD) status packet and received in the negotiation step.

In addition, the foreign matter detection method may further include outputting a predetermined alarm signal informing that the foreign matter has been detected when the foreign matter is present as a result of the determination, and may enter a selection step after outputting the alarm signal.

In addition, as a result of the determination, if the foreign matter does not exist, the negotiation step or the power transmission step may be entered.

In addition, the foreign material detection method may further include performing a foreign material detection procedure based on the quality factor value, if the foreign material exists as a result of the determination.

In addition, the foreign matter detection method may further include transmitting a NACK packet to a corresponding wireless power receiver when it is determined that the foreign matter is present through the foreign matter detection procedure based on the quality factor value.

The foreign matter detection method may further include transmitting an ACK packet to a corresponding wireless power receiver when it is determined that a foreign matter is present through a foreign matter detection procedure based on the quality factor value.

In addition, the foreign matter detection method may further include receiving an FOD status packet in the negotiation step and then transmitting an ACK packet to a corresponding wireless power receiver when the foreign matter does not exist as a result of the determination.

A foreign matter detection method in a wireless power transmitter according to another embodiment of the present invention includes calculating a rate of change of current input to an inverter in a ping step, receiving a packet including a receiver type identifier, and the receiver type identifier The method may include determining a current intensity threshold ratio for detecting a corresponding foreign material and determining whether a foreign material is present by comparing the calculated current change ratio with the current intensity threshold ratio.

Here, the rate of change of the current input to the inverter may be calculated as a rate of change of the current intensity value of the inverter input current measured in the ping step to the current intensity value input to the initial inverter in a state in which an object is not detected.

In addition, the step of determining whether or not the foreign material exists includes determining that the foreign material is present when the calculated rate of change of current exceeds the current intensity threshold rate, and the calculated rate of change of current is the current intensity threshold rate. If it is less than or equal to the ratio, determining that the foreign matter does not exist may be included.

In addition, the receiver type identifier may be included in a configuration packet and received in the configuration and identification step.

Also, the receiver type identifier may be included in a Foreign Object Detection (FOD) status packet and received in the negotiation step.

In addition, the foreign matter detection method may further include outputting a predetermined alarm signal informing that the foreign matter has been detected when the foreign matter is present as a result of the determination, and may enter a selection step after outputting the alarm signal.

In addition, the foreign matter detection method may further include controlling to enter a negotiation step or a power transmission step when the foreign matter does not exist as a result of the determination.

A foreign matter detection apparatus according to another embodiment of the present invention includes a sensing unit for measuring the intensity of current input to an inverter in a ping step, a demodulation unit for receiving a packet including a receiver type identifier, and the receiver type identifier corresponding to each other. A control unit may be configured to determine a threshold value for detecting a foreign substance and compare the measured current intensity with the threshold value to determine whether a foreign substance is present.

An apparatus for detecting foreign matter according to another embodiment of the present invention includes a sensing unit for measuring the intensity of current input to an inverter in a ping step, a demodulation unit for receiving a packet including a receiver type identifier, and the sensing unit to detect the Calculate the rate of change of the current input to the inverter, determine the threshold rate of current intensity for detecting foreign matter corresponding to the receiver type identifier, and compare the rate of change of current with the threshold rate of current intensity to detect the existence of the foreign substance. It may include a control unit that determines.

In addition, the foreign matter detection device may include a DC-DC converter for converting DC power applied from a power source into specific DC power; and the inverter converting the converted DC power into AC power, and the sensing unit may measure the intensity of current flowing between the DC-DC converter and the inductor.

In addition, the foreign matter detection device may further include an LC resonance circuit including a resonance capacitor and an inductor for wirelessly transmitting the AC power.

Another embodiment of the present invention may be provided with a computer-readable recording medium recording a program for executing any one of the foreign material detection methods.

The above aspects of the present invention are only some of the preferred embodiments of the present invention, and various embodiments in which the technical features of the present invention are reflected are detailed descriptions of the present invention to be detailed below by those skilled in the art. It can be derived and understood based on.

Effects of the method, apparatus and system according to the present invention are described as follows.

The present invention has the advantage of providing a foreign matter detection method for wireless charging and a device and system therefor.

In addition, the present invention has an advantage of providing a wireless power transmitter capable of more accurately detecting foreign matter.

In addition, the present invention has the advantage of minimizing unnecessary power waste and heat generation caused by foreign substances.

In addition, the present invention has an advantage of providing a foreign material detection method capable of more accurate detection of a foreign material by determining a threshold for dynamically determining the existence of a foreign material according to a type of receiver, and an apparatus and system using the same.

The effects obtainable in the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description below. will be.

1 is a block diagram for explaining a wireless charging system according to an embodiment of the present invention.
2 is a block diagram for explaining a wireless charging system according to another embodiment of the present invention.
3 is a diagram for explaining a detection signal transmission procedure in a wireless charging system according to an embodiment of the present invention.
4 is a state transition diagram for explaining a wireless power transmission procedure defined in the WPC standard.
5 is a state transition diagram for explaining a wireless power transmission procedure defined in the WPC (Qi) standard.
6 is a block diagram for explaining the structure of a wireless power transmitter according to an embodiment of the present invention.
FIG. 7 is a block diagram for explaining the structure of a wireless power receiver interworking with the wireless power transmitter of FIG. 6 .
8 is a diagram for explaining a method of modulating and demodulating a wireless power signal according to an embodiment of the present invention.
9 is a diagram for explaining a packet format according to an embodiment of the present invention.
10 is a diagram for explaining packet types defined in the WPC (Qi) standard according to an embodiment of the present invention.
11 is a block diagram for explaining the structure of a foreign matter detection device according to an embodiment of the present invention.
12 is a diagram for explaining a message structure of a FOD status packet according to an embodiment of the present invention.
13 is a diagram for explaining a message structure of a configuration packet according to an embodiment of the present invention.
14 is a receiver type identifier mapping table in which current change thresholds corresponding to receiver type identifiers are defined according to an embodiment of the present invention.
15 is a receiver type identifier mapping table in which current change threshold ratios corresponding to receiver type identifiers are defined according to another embodiment of the present invention.
16 is a flowchart illustrating a method of detecting a foreign object in a wireless power transmission device according to an embodiment of the present invention.
17 is a flowchart illustrating a method of detecting a foreign object in a wireless power transmission device according to another embodiment of the present invention.
18 is a flowchart illustrating a method of detecting a foreign material in a wireless power transmission device according to another embodiment of the present invention.
19 is an embodiment of a transmission coil mounted in a wireless power transmission device according to an embodiment of the present invention.
20A to 20B are graphs showing measurement results of the inductor input current intensity and the transmission coil input current intensity for each position of the transmission coil according to FIG. 19 .
21 and 22 show a change pattern of coil current and inverter input current when a foreign material is located in the charging area in the ping step in Position 1 of FIG. 19 .

Hereinafter, an apparatus and various methods to which embodiments of the present invention are applied will be described in more detail with reference to the drawings. The suffixes "module" and "unit" for components used in the following description are given or used together in consideration of ease of writing the specification, and do not have meanings or roles that are distinct from each other by themselves.

In the description of the embodiment, in the case where it is described as being formed on the "top (top) or bottom (bottom)" of each component, the top (top) or bottom (bottom) means that two components are in direct contact with each other or One or more other components are formed by being disposed between two components. In addition, when expressed as “up (up) or down (down)”, it may include the meaning of not only the upward direction but also the downward direction based on one component.

In the description of the embodiment, a device equipped with a function of transmitting wireless power on a wireless charging system is a wireless power transmitter, a wireless power transmitter, a wireless power transmitter, a wireless power transmitter, a transmitter, a transmitter, and a transmitter for convenience of description. , a transmitting side, a wireless power transmitter, a wireless power transmitter, etc. will be used interchangeably. In addition, it is an expression for a device equipped with a function of receiving wireless power from a wireless power transmitter, and for convenience of explanation, a wireless power receiver, a wireless power receiver, a wireless power receiver, a wireless power receiver, a receiving terminal, a receiving side, A receiving device, a receiver, and the like may be used interchangeably.

The transmitter according to the present invention may be configured in a pad type, a cradle type, an access point (AP) type, a small base station type, a stand type, a ceiling buried type, a wall hanging type, etc. Power can also be transmitted. To this end, the transmitter may include at least one wireless power transmission unit. Here, the wireless power transmission unit generates a magnetic field in the coil of the power transmitter and uses the principle of electromagnetic induction in which electricity is induced in the coil of the receiver under the influence of the magnetic field, and various wireless power transmission standards based on the electromagnetic induction method may be used. Here, the wireless power transmission unit may include an electromagnetic induction type wireless charging technology defined by the Wireless Power Consortium (WPC) and the Power Matters Alliance (PMA), which are wireless charging technology standard organizations.

In addition, the receiver according to an embodiment of the present invention may include at least one wireless power receiving unit, and may simultaneously receive wireless power from two or more transmitters. Here, the wireless power receiver may include electromagnetic induction type wireless charging technology defined by the Wireless Power Consortium (WPC) and the Power Matters Alliance (PMA), which are wireless charging technology standard organizations.

The receiver according to the present invention is a mobile phone, a smart phone, a laptop computer, a digital broadcasting terminal, a PDA (Personal Digital Assistants), a PMP (Portable Multimedia Player), a navigation device, an MP3 player, an electric motor It can be used for small electronic devices such as toothbrushes, electronic tags, lighting devices, remote controls, fishing floats, and wearable devices such as smart watches, but is not limited thereto, and is equipped with a wireless power receiving means according to the present invention and can charge a battery. enough

1 is a block diagram for explaining a wireless charging system according to an embodiment of the present invention.

Referring to FIG. 1, the wireless charging system includes a wireless power transmitter 10 that wirelessly transmits power, a wireless power receiver 20 that receives the transmitted power, and an electronic device 30 that receives the received power. can be configured.

For example, the wireless power transmitter 10 and the wireless power receiver 20 may perform in-band communication for exchanging information using the same frequency band as an operating frequency used for wireless power transmission. As another example, the wireless power transmitter 10 and the wireless power receiver 20 perform out-of-band communication for exchanging information using a separate frequency band different from the operating frequency used for wireless power transmission. can also be done

For example, information exchanged between the wireless power transmitter 10 and the wireless power receiver 20 may include control information as well as status information of each other. Here, status information and control information exchanged between the transmitting and receiving terminals will become more clear through the description of embodiments to be described later.

The in-band communication and the out-of-band communication may provide bi-directional communication, but are not limited thereto, and in another embodiment, uni-directional communication or half-duplex communication may be provided.

For example, one-way communication may be transmission of information only from the wireless power receiver 20 to the wireless power transmitter 10, but is not limited thereto, and the wireless power transmitter 10 transmits information to the wireless power receiver 20. may be to transmit.

The half-duplex communication method is characterized in that two-way communication is possible between the wireless power receiver 20 and the wireless power transmitter 10, but information can be transmitted only by one device at any one time.

The wireless power receiver 20 according to an embodiment of the present invention may obtain various state information of the electronic device 30. For example, the status information of the electronic device 30 may include current power usage information, information for identifying an application being executed, CPU usage information, battery charge state information, battery output voltage/current information, etc., but is limited thereto. It is not, and information obtainable from the electronic device 30 and usable for wireless power control is sufficient.

In particular, the wireless power transmitter 10 according to an embodiment of the present invention may transmit a predetermined packet indicating whether to support fast charging to the wireless power receiver 20. When it is confirmed that the connected wireless power transmitter 10 supports the fast charging mode, the wireless power receiver 20 may inform the electronic device 30 of this. The electronic device 30 may display that high-speed charging is possible through a predetermined display unit provided therein, which may be, for example, a liquid crystal display.

In addition, the user of the electronic device 30 may control the wireless power transmitter 10 to operate in the fast charging mode by selecting a predetermined fast charging request button displayed on the liquid crystal display unit. In this case, when the fast charging request button is selected by the user, the electronic device 30 may transmit a predetermined fast charging request signal to the wireless power receiver 20 . The wireless power receiver 20 may convert the normal low power charging mode into the fast charging mode by generating a charging mode packet corresponding to the received fast charging request signal and transmitting the packet to the wireless power transmitter 10 .

2 is a block diagram for explaining a wireless charging system according to another embodiment of the present invention.

For example, as shown at reference numeral 200a, the wireless power receiver 20 may be composed of a plurality of wireless power receivers, and a plurality of wireless power receivers are connected to one wireless power transmitter 10 to provide wireless Charging can also be performed. At this time, the wireless power transmitter 10 may distribute and transmit power to a plurality of wireless power receivers in a time division manner, but is not limited thereto. As another example, the wireless power transmitter 10 may distribute and transmit power to a plurality of wireless power receivers using different frequency bands allocated to each wireless power receiver.

At this time, the number of wireless power receivers connectable to one wireless power transmitter 10 depends on at least one of the amount of power required for each wireless power receiver, the state of charge of the battery, the power consumption of the electronic device, and the amount of available power of the wireless power transmitter. can be adaptively determined based on

As another example, as shown in reference numeral 200b, the wireless power transmitter 10 may be composed of a plurality of wireless power transmitters. In this case, the wireless power receiver 20 may be simultaneously connected to a plurality of wireless power transmitters, and may simultaneously receive power from the connected wireless power transmitters and perform charging. At this time, the number of wireless power transmitters connected to the wireless power receiver 20 is adaptively based on the amount of power required by the wireless power receiver 20, the state of charge of the battery, the power consumption of the electronic device, and the amount of available power of the wireless power transmitter. can be determined

3 is a diagram for explaining a detection signal transmission procedure in a wireless charging system according to an embodiment of the present invention.

For example, the wireless power transmitter may be equipped with three transmission coils 111, 112, and 113. Each transmission coil may have a partial area overlapping with other transmission coils, and the wireless power transmitter may send predetermined detection signals 117 and 127 for detecting the presence of a wireless power receiver through each transmission coil - for example, Digital ping signals are sent sequentially in a predefined order.

As shown in FIG. 3, the wireless power transmitter sequentially transmits the detection signal 117 through the primary detection signal transmission procedure shown in reference number 110, and the signal strength indicator (Signal Strength Indicator) from the wireless power receiver 115 The strength indicator 116 may identify the received transmission coils 111 and 112 . Subsequently, the wireless power transmitter sequentially transmits the detection signal 127 through the secondary detection signal transmission procedure shown in reference numeral 120, and transmits power among the transmission coils 111 and 112 having received the signal strength indicator 126. Efficiency (or charging efficiency) - that is, the alignment between the transmitting coil and the receiving coil - is identified, and power is transmitted through the identified transmitting coil - that is, wireless charging is performed - can be controlled. .

As shown in FIG. 3 above, the reason why the wireless power transmitter performs the detection signal transmission procedure twice is to more accurately identify to which transmission coil the receiving coil of the wireless power receiver is well aligned.

If, as shown in reference numerals 110 and 120 of FIG. 3 above, when the signal strength indicators 116 and 126 are received by the first transmission coil 111 and the second transmission coil 112, the wireless power transmitter selects the most aligned transmission coil based on the signal strength indicator 126 received in each of the first transmission coil 111 and the second transmission coil 112, and performs wireless charging using the selected transmission coil. .

4 is a state transition diagram for explaining a wireless power transmission procedure defined in the WPC standard.

Referring to FIG. 4, power transmission from a transmitter to a receiver according to the WPC standard largely includes a selection phase (Selection Phase) 410, a ping phase (420), an identification and configuration phase (430), It can be divided into power transfer phase (Power Transfer Phase, 440).

The selection step 410 may be a transition step when a specific error or specific event is detected while power transmission is started or maintained. Here, specific errors and specific events will become clear through the following description. Also, in selection step 410, the transmitter may monitor whether an object is present on the interface surface. If the transmitter detects that an object is placed on the interface surface, it may transition to a ping step (420) (S401). In the selection step 410, the transmitter transmits an analog ping signal of a very short pulse, and based on the current change of the transmitting coil, it is possible to detect whether an object exists in the active area of the interface surface.

In the ping step 420, when an object is detected, the transmitter activates the receiver and transmits a digital ping to identify whether the receiver is compatible with the WPC standard. In the ping step 420, if the transmitter does not receive a digital ping response signal—eg, a signal strength indicator—from the receiver, it may transition to the selection step 410 again (S402). In addition, in the ping step 420, when the transmitter receives a signal indicating that power transmission has been completed—ie, a charge completion signal—from the receiver, the transmitter may proceed to the selection step 410 (S403).

When the ping step 420 is completed, the transmitter may transition to the identification and configuration step 430 for collecting receiver identification and receiver configuration and status information (S404).

In the identification and configuration step 430, the transmitter determines whether an undesired packet has been received (unexpected packet), a desired packet has not been received for a predefined period of time (time out), there is a packet transmission error (transmission error), or a power transmission agreement. If this is not set (no power transfer contract), the process may proceed to the selection step 410 (S405).

When the identification and configuration of the receiver is completed, the transmitter may transition to a power transmission step 440 of transmitting wireless power (S406).

In the power transmission step 440, the transmitter receives an unwanted packet (unexpected packet), a desired packet is not received for a predefined time (time out), or a violation of a preset power transmission contract occurs (power transmission step 440). transfer contract violation), when charging is completed, it may transition to the selection step (410) (S407).

In addition, in the power transmission step 440, the transmitter may transition to the identification and configuration step 430 when it is necessary to reconfigure the power transmission contract according to a change in the transmitter state (S408).

The power transmission contract described above may be established based on state and characteristic information of a transmitter and a receiver. For example, the transmitter status information may include information on the maximum amount of transmittable power and information on the maximum number of receivers that can be accommodated, and the receiver status information may include information on required power.

5 is a state transition diagram for explaining a wireless power transmission procedure defined in the WPC (Qi) standard.

Referring to FIG. 5, power transmission from a transmitter to a receiver according to the WPC (Qi) standard largely includes a selection phase (510), a ping phase (520), and an identification and configuration phase (Identification and Configuration Phase). 530), a negotiation phase (Negotiation Phase, 540), a calibration phase (550), a power transfer phase (560), and a renegotiation phase (570).

The selection step 510 may be a transition step when a specific error or a specific event is detected while power transmission is started or power transmission is maintained. Here, specific errors and specific events will become clear through the following description. Also, in selection step 510, the transmitter may monitor whether an object is present on the interface surface. If the transmitter detects that an object is placed on the interface surface, it may transition to step 520 of pinging. In the selection step 510, the transmitter transmits a very short pulse analog ping signal, and based on the current change of the transmitting coil or primary coil, the object is placed in the active area of the interface surface. can detect whether it exists.

In the ping step 520, when an object is detected, the transmitter activates the receiver and transmits a digital ping to identify whether the receiver is compatible with the WPC standard. In the ping step 520, if the transmitter does not receive a digital ping response signal (for example, a signal strength packet) from the receiver, it may proceed to the selection step 510 again. In addition, in the ping step 520, when the transmitter receives a signal indicating that power transmission has been completed—that is, a charge completion packet—from the receiver, the transmitter may proceed to the selection step 510.

Once the ping phase 520 is complete, the transmitter may transition to an identification and configuration phase 530 to identify the receiver and collect receiver configuration and status information.

In the identification and configuration step 530, the transmitter determines whether an undesired packet has been received (unexpected packet), a desired packet has not been received for a predefined period of time (time out), there is a packet transmission error (transmission error), or a power transmission agreement. If this is not set (no power transfer contract), the process may proceed to selection step 510 .

The transmitter may check whether it is necessary to enter the negotiation step 540 based on the negotiation field value of the configuration packet received in the identification and configuration step 530.

As a result of the check, if negotiation is necessary, the transmitter may enter the negotiation step 540 and perform a predetermined FOD detection procedure.

On the other hand, as a result of confirmation, if negotiation is not required, the transmitter may directly enter the power transmission step 560.

In the negotiation step 540, the transmitter may receive a Foreign Object Detection (FOD) status packet including the reference quality factor value. In this case, the transmitter may determine a threshold for FO detection based on the reference quality factor value.

Various methods for the transmitter to determine the threshold for FO detection based on the reference quality factor value will be described in detail with reference to drawings to be described later.

The transmitter may detect whether FO exists in the charging area using the determined threshold value and the currently measured value of the quality factor, and may control power transmission based on the FO detection result.

As an example, if FO is detected, the transmitter may return to selection step 510 . On the other hand, if FO is not detected, the transmitter may go through the calibration step 550 and enter the power transfer step 560. In detail, when the transmitter does not detect FO, in the correction step 550, the transmitter determines the strength of the power received by the receiving end, and calculates the power loss at the receiving end and the transmitting end to determine the strength of the power transmitted by the transmitting end. can be measured That is, the transmitter can estimate the power loss based on the difference between the transmission power of the transmitter and the reception power of the receiver in the calibration step 550 . The transmitter according to an embodiment may correct the threshold for FOD detection by reflecting the predicted power loss.

In the power transmission step 560, the transmitter receives an unwanted packet (unexpected packet), a desired packet is not received for a predefined time (time out), or a violation of a preset power transmission contract occurs (power transmission step 560). transfer contract violation), when charging is completed, the selection step 510 may be performed.

In addition, in the power transmission step 560, the transmitter may transition to the renegotiation step 570 if it is necessary to reconfigure the power transmission contract according to a change in transmitter status. At this time, if renegotiation is normally completed, the transmitter may return to power transmission step 560.

The power transmission contract described above may be established based on state and characteristic information of a transmitter and a receiver. For example, the transmitter status information may include information on the maximum amount of transmittable power and information on the maximum number of receivers that can be accommodated, and the receiver status information may include information on required power.

6 is a block diagram for explaining the structure of a wireless power transmitter according to an embodiment of the present invention.

Referring to FIG. 6 , the wireless power transmitter 600 may include a power conversion unit 610, a power transmission unit 620, a communication unit 630, a control unit 640, and a sensing unit 650. . It should be noted that the configuration of the wireless power transmitter 600 described above is not necessarily an essential configuration, and may be configured to include more or fewer components.

As shown in FIG. 6 , when power is supplied from the power source 660, the power conversion unit 610 may perform a function of converting the power into power of a predetermined intensity.

To this end, the power converter 610 may include a DC/DC converter 611 and an amplifier 612 .

The DC/DC conversion unit 611 may perform a function of converting DC power supplied from the power supply unit 650 into DC power of a specific intensity according to a control signal from the control unit 640 .

In this case, the sensing unit 650 may measure the voltage/current of the DC-converted power and provide the measured voltage/current to the control unit 640 . In addition, the sensing unit 650 may measure the internal temperature of the wireless power transmitter 600 to determine whether overheating has occurred and provide the measurement result to the control unit 640 . For example, the control unit 640 may adaptively cut off power supply from the power supply unit 650 or cut off power supply to the amplifier 612 based on the voltage/current value measured by the sensing unit 650. can To this end, a predetermined power cut-off circuit may be further provided on one side of the power converter 610 to cut off the power supplied from the power supply unit 650 or the power supplied to the amplifier 612.

The amplifier 612 may adjust the intensity of DC/DC converted power according to a control signal from the controller 640 . For example, the controller 640 may receive power reception state information or/and a power control signal of the wireless power receiver through the communication unit 630, based on the received power reception state information or/and power control signal. Thus, the amplification factor of the amplifier 612 can be dynamically adjusted. For example, the power reception state information may include information on the intensity of a rectifier output voltage, information on the intensity of a current applied to a receiving coil, etc., but is not limited thereto. The power control signal may include a signal for requesting a power increase, a signal for requesting a power decrease, and the like.

The power transmitter 620 may include a multiplexer 621 (or multiplexer) and a transmission coil 622 . In addition, the power transmitter 620 may further include a carrier generator (not shown) for generating a specific operating frequency for power transmission.

The carrier generator may generate a specific frequency for converting the output DC power of the amplifier 612 received through the multiplexer 621 into AC power having a specific frequency. In the above description, it is described that the AC signal generated by the carrier generator is mixed with the output terminal of the multiplexer 621 to generate AC power, but this is only one embodiment, and another example is before the amplifier 612 It should be noted that it may be mixed in a stage or a later stage.

It should be noted that frequencies of AC power delivered to respective transmission coils according to an embodiment of the present invention may be different from each other. In another embodiment of the present invention, the resonance frequency for each transmission coil may be set differently using a predetermined frequency controller equipped with a function of differently adjusting the LC resonance characteristics for each transmission coil.

As shown in FIG. 6, the power transmission unit 620 includes a multiplexer 621 and a plurality of transmission coils 622 for controlling the transmission of the output power of the amplifier 612 to the transmission coil - that is, the first to n-th transmission coils.

When a plurality of wireless power receivers are connected, the control unit 640 according to an embodiment of the present invention may transmit power through time division multiplexing for each transmission coil. For example, when three wireless power receivers in the wireless power transmitter 600—that is, first to third wireless power receivers—are respectively identified through three different transmission coils—that is, first to third transmission coils— , The controller 640 may control the multiplexer 621 to transmit power to a specific transmission coil at a specific time slot. At this time, the amount of power transmitted to the corresponding wireless power receiver may be controlled according to the length of the time slot allocated to each transmitting coil, but this is only one embodiment, and another example is during the tile slot allocated to each transmitting coil. Transmission power for each wireless power receiver may be controlled by controlling the amplification rate of the amplifier 612 of the amplifier 612 .

The controller 640 may control the multiplexer 621 so that detection signals are sequentially transmitted through the first through n-th transmission coils 622 during the first detection signal transmission procedure. At this time, the control unit 640 can identify the timing at which the sensing signal is transmitted using the timer 655, and when the sensing signal transmission timing arrives, the control unit 640 controls the multiplexer 621 so that the sensing signal is transmitted through the corresponding transmission coil. You can control it so that it can be sent out. For example, the timer 655 may transmit a specific event signal to the control unit 640 at predetermined intervals during the ping transmission step, and when the corresponding event signal is detected, the control unit 640 controls the multiplexer 621 to transmit the corresponding event signal. It can be controlled so that digital ping can be sent through the coil.

In addition, the control unit 640 provides a predetermined transmission coil identifier and a corresponding transmission coil for identifying through which transmission coil the signal strength indicator was received from the demodulation unit 632 during the first detection signal transmission procedure. It is possible to receive the signal strength indicator received through. Subsequently, in the second detection signal transmission procedure, the control unit 640 controls the multiplexer 621 so that the detection signal is transmitted only through the transmission coil(s) having received the signal strength indicator during the first detection signal transmission procedure. You may. As another example, when there are a plurality of transmission coils receiving the signal strength indicator during the first detection signal transmission procedure, the control unit 640 transmits the second detection signal to the transmission coil having the signal strength indicator having the largest value. In the procedure, a transmission coil to transmit a detection signal first is determined, and the multiplexer 621 may be controlled according to the determined result.

The modulator 631 may modulate the control signal generated by the control unit 640 and transmit the modulated signal to the multiplexer 621 . Here, the modulation method for modulating the control signal is a frequency shift keying (FSK) modulation method, a Manchester coding modulation method, a phase shift keying (PSK) modulation method, a pulse width modulation method, and a differential 2 Differential bi-phase modulation may be included, but is not limited thereto.

When a signal received through the transmission coil is detected, the demodulator 632 may demodulate and transmit the detected signal to the controller 640 . Here, the demodulated signal may include a signal strength indicator, an error correction (EC) indicator for power control during wireless power transmission, an end of charge (EOC) indicator, an overvoltage/overcurrent/overheat indicator, etc. , but is not limited thereto, and various state information for identifying the state of the wireless power receiver may be included.

In addition, the demodulation unit 632 may identify from which transmission coil the demodulated signal is received, and may provide the control unit 640 with a predetermined transmission coil identifier corresponding to the identified transmission coil.

Also, the demodulator 632 may demodulate the signal received through the transmission coil 623 and transmit the demodulated signal to the controller 640 . For example, the demodulated signal may include a signal strength indicator, but is not limited thereto, and the demodulated signal may include various state information of the wireless power receiver.

For example, the wireless power transmitter 600 may acquire the signal strength indicator through in-band communication that communicates with the wireless power receiver using the same frequency used for wireless power transmission.

In addition, the wireless power transmitter 600 can transmit wireless power using the transmission coil 622 and exchange various types of information with the wireless power receiver through the transmission coil 622 . As another example, the wireless power transmitter 600 further includes separate coils corresponding to the transmission coils 622 (that is, the first to nth transmission coils), and uses the provided separate coils to transmit wireless power. It should be noted that in-band communication may be performed with the receiver.

In the above description of FIG. 6, the wireless power transmitter 600 and the wireless power receiver perform in-band communication as an example, but this is only one embodiment and a frequency band used for wireless power signal transmission. Short-distance two-way communication may be performed through a frequency band different from the above. For example, short-distance two-way communication may be any one of low power Bluetooth communication, RFID communication, UWB communication, and ZigBee communication.

In particular, the wireless power transmitter 600 according to an embodiment of the present invention may adaptively provide a fast charging mode and a general low power charging mode according to a request of a wireless power receiver.

When the fast charging mode is supported, the wireless power transmitter 600 may transmit a signal of a predetermined pattern - for convenience of description below, a business card referred to as a first packet. When the first packet is received, the wireless power receiver 600 may identify that the connected wireless power transmitter 600 is capable of high-speed charging.

In particular, when fast charging is required, the wireless power receiver may transmit a predetermined first response packet requesting fast charging to the wireless power transmitter 600 .

In particular, the wireless power transmitter 600 may automatically switch to a fast charging mode and start fast charging when a predetermined time elapses after receiving the first response packet.

For example, the control unit 640 of the wireless power transmitter 600 controls the first packet to be transmitted through the transmission coil 622 when the transition to the power transmission step 440 or 560 of FIGS. 4 to 5 is performed. However, this is only one embodiment, and in another example of the present invention, the first packet may be transmitted in the identification and configuration step 430 of FIG. 4 or the identification step 530 of FIG.

It should be noted that in another embodiment of the present invention, information for identifying whether fast charging is supported may be encoded and transmitted in the digital ping signal transmitted by the wireless power transmitter 600 .

If high-speed charging is required at any point in the power transmission step, the wireless power receiver may transmit a predetermined charging mode packet in which the charging mode is set to high-speed charging to the wireless power transmitter 600 . Here, the detailed configuration of the charging mode packet will be further clarified through the description of FIGS. 8 to 12 to be described later. Of course, when the charging mode is changed to the fast charging mode, the wireless power transmitter 600 and the wireless power receiver are in the fast charging mode. It is possible to control the internal operation so that the power corresponding to can be transmitted and received. For example, when the charging mode is changed from the general low-power charging mode to the high-speed charging mode, the overvoltage criterion, the over temperature criterion, the low voltage/high voltage criterion, and the optimal voltage Values such as level (optimum voltage level) and power control offset may be changed and set.

For example, when the charging mode is changed from the normal low power charging mode to the fast charging mode, the threshold voltage for overvoltage determination may be set high to enable fast charging. As another example, a threshold temperature for determining whether overheating may occur may be set high in consideration of a temperature rise due to high-speed charging. As another example, the power control offset value, which means the minimum level at which the power of the transmitter is controlled, may be set to a larger value than that of the general low power charging mode so that the high-speed charging mode can quickly converge to a desired target power level.

FIG. 7 is a block diagram for explaining the structure of a wireless power receiver interworking with the wireless power transmitter of FIG. 6 .

Referring to FIG. 7 , the wireless power receiver 700 includes a receiving coil 710, a rectifier 720, a DC/DC converter 730, a load 740, a sensing unit 750, a communication unit ( 760) and a main control unit 770. Here, the communication unit 760 may include a demodulation unit 761 and a modulation unit 762.

The wireless power receiver 700 shown in the example of FIG. 7 is shown as being able to exchange information with the wireless power transmitter 600 through in-band communication, but this is only one embodiment, and the present invention The communication unit 760 according to another embodiment of may provide short-range two-way communication through a frequency band different from a frequency band used for wireless power signal transmission.

AC power received through the receiving coil 710 may be transmitted to the rectifier 720 . The rectifier 720 may convert AC power into DC power and transmit it to the DC/DC converter 730 . The DC/DC converter 730 may convert the intensity of the DC power output from the rectifier into a specific intensity required by the load 740 and then transfer the intensity to the load 740 .

The sensing unit 750 may measure the intensity of DC power output from the rectifier 720 and provide it to the main control unit 770 . In addition, the sensing unit 750 may measure the intensity of current applied to the receiving coil 710 according to wireless power reception and transmit the measurement result to the main controller 770 . Also, the sensing unit 750 may measure the internal temperature of the wireless power receiver 700 and provide the measured temperature value to the main controller 770 .

For example, the main control unit 770 may determine whether an overvoltage occurs by comparing the measured intensity of the output DC power of the rectifier with a predetermined reference value. As a result of the determination, when an overvoltage occurs, a predetermined packet notifying that an overvoltage has occurred may be generated and transmitted to the modulator 762 . Here, the signal modulated by the modulator 762 may be transmitted to the wireless power transmitter 600 through the receiving coil 710 or a separate coil (not shown). In addition, the main control unit 770 may determine that the detection signal is received when the intensity of the DC power output from the rectifier is greater than or equal to a predetermined reference value, and when the detection signal is received, the signal strength indicator corresponding to the detection signal is displayed by the modulator 762 ) to be transmitted to the wireless power transmitter 600. As another example, the demodulation unit 761 may output an AC power signal between the receiving coil 710 and the rectifier 720 or the output of the rectifier 720. After demodulating the DC power signal to determine whether or not the detection signal has been received, the identification result may be provided to the main controller 770 . In this case, the main controller 770 may control the signal strength indicator corresponding to the detection signal to be transmitted through the modulator 762 .

In particular, the main controller 770 according to an embodiment of the present invention may determine whether the wireless power transmitter connected to the wireless power transmitter capable of high-speed charging is based on information demodulated by the demodulator 761 .

In addition, when a predetermined fast charging request signal requesting fast charging is received from the electronic device 30 of FIG. (762). Here, the fast charging request signal from the electronic device may be received according to a user menu selection on a predetermined user interface.

When it is confirmed that the connected wireless power transmitter supports the fast charging mode, the main control unit 770 according to another embodiment of the present invention automatically requests fast charging to the wireless power transmitter based on the remaining battery capacity or wireless power The transmitter can also be controlled to stop fast charging and switch to normal low power charging mode.

The main controller 770 according to another embodiment may monitor the power consumption of the electric device in real time during charging in a general low power charging mode. If the power consumption of the electronic device is greater than or equal to a predetermined reference value, the main control unit 770 may generate a predetermined charging mode packet requesting conversion to the fast charging mode and transmit it to the modulator 762 .

The main controller 770 according to another embodiment of the present invention may compare the internal temperature value measured by the sensing unit 750 with a predetermined reference value to determine whether overheating occurs. If overheating occurs during fast charging, the main controller 770 may generate and transmit a charging mode packet so that the wireless power transmitter switches to a general low power charging mode.

The main control unit 770 according to another embodiment of the present invention changes the charging mode based on at least one of the battery charging rate, internal temperature, strength of the rectifier output voltage, CPU usage rate mounted in the electronic device, and user menu selection. It is determined whether or not the charging mode is necessary, and as a result of the determination, if the charging mode needs to be changed, a charging mode packet including the charging mode value to be changed may be generated and transmitted to the wireless power transmitter.

8 is a diagram for explaining a method of modulating and demodulating a wireless power signal according to an embodiment of the present invention.

As shown in reference numeral 810 of FIG. 8 , the wireless power transmitter 10 and the wireless power receiver 20 may encode or decode a packet to be transmitted based on an internal class signal having the same period.

Hereinafter, a method of encoding a to-be-transmitted packet will be described in detail with reference to FIGS. 1 to 8.

Referring to FIG. 1, when the wireless power transmitter 10 or the wireless power receiver 20 does not transmit a specific packet, the wireless power signal is modulated with a specific frequency, as shown in reference numeral 41 of FIG. It may be an unresolved AC signal. On the other hand, when the wireless power transmitter 10 or the wireless power receiver 20 transmits a specific packet, the wireless power signal may be an AC signal modulated by a specific modulation method, as shown in reference numeral 42 of FIG. 1. For example, the modulation method may include an amplitude modulation method, a frequency modulation method, a frequency and amplitude modulation method, a phase modulation method, and the like, but is not limited thereto.

Differential bi-phase encoding may be applied to the binary data of the packet generated by the wireless power transmitter 10 or the wireless power receiver 20, as shown in reference number 820. Specifically, differential two-level encoding has two state transitions to encode data bit 1 and one state transition to encode data bit 0. That is, data bit 1 is encoded such that a transition between the HI state and the LO state occurs at the rising edge and falling edge of the clock signal, and data bit 0 is HI at the rising edge of the clock signal. It may be encoded such that transitions between states and LO states occur.

The encoded binary data may be subjected to a byte encoding technique as shown in reference numeral 830 above. Referring to reference number 830, a byte encoding technique according to an embodiment includes a start bit and a stop bit for identifying the start and type of a corresponding bit stream for an 8-bit encoded binary bit stream. , it may be a method of inserting a parity bit for detecting whether an error has occurred in the corresponding bit stream (byte).

9 is a diagram for explaining a packet format according to an embodiment of the present invention.

Referring to FIG. 9 , a packet format 900 used for information exchange between a wireless power transmitter 10 and a wireless power receiver 20 is used to obtain synchronization for demodulation of a corresponding packet and to identify an accurate start bit of the corresponding packet. A preamble (910) field for transmission, a header (920) field for identifying the type of message included in the corresponding packet, and a message (Message, 930) field and a checksum field 940 for identifying whether an error has occurred in the corresponding packet.

As shown in FIG. 9 , the packet receiver may identify the size of the message 930 included in the corresponding packet based on the header 920 value.

In addition, the header 920 may be defined for each step of the wireless power transmission procedure, and the same value of the header 920 may be partially defined in different steps. For example, referring to FIG. 9 , it should be noted that the header value corresponding to end power transfer of the ping step and power transfer end of the power transfer step may be the same as 0x02.

The message 930 includes data to be transmitted by the transmitter of the corresponding packet. For example, data included in the field of the message 930 may be a report, a request, or a response to the other party, but is not limited thereto.

The packet 900 according to another embodiment of the present invention may further include at least one of transmitter identification information for identifying a transmitter that has transmitted the packet and receiver identification information for identifying a receiver to receive the packet. Here, the transmitting end identification information and the receiving end identification information may include IP address information, MAC address information, product identification information, etc., but are not limited thereto, and any information capable of distinguishing between a receiving end and a transmitting end on a wireless charging system is sufficient.

If the packet 900 according to another embodiment of the present invention is to be received by a plurality of devices, it may further include predetermined group identification information for identifying the corresponding reception group.

10 is a diagram for explaining types of packets transmitted from a wireless power receiver to a wireless power transmitter according to an embodiment of the present invention.

Referring to FIG. 10, the packets transmitted from the wireless power receiver to the wireless power transmitter include a signal strength packet for transmitting strength information of a detected ping signal and a power transmission type for requesting the transmitter to stop power transmission. (End Power Transfer), Power Control Hold-off packet to transmit waiting time information until actual power is adjusted after receiving a control error packet for control control, configuration to transmit configuration information of a receiver packet, identification packet and extended identification packet for transmitting receiver identification information, general request packet for transmitting general request message, special request packet for transmitting special request message, and reference quality factor value for FO detection. FOD status packet, control error packet for controlling transmit power of transmitter, renegotiation packet for initiating renegotiation, 24-bit received power packet and 8-bit received power packet for transmitting received power intensity information, and charging status information of current load It may include a charge status packet for transmitting.

Packets transmitted from the wireless power receiver to the wireless power transmitter may be transmitted using in-band communication using the same frequency band as that used for wireless power transmission.

11 is a block diagram for explaining the structure of a foreign matter detection device according to an embodiment of the present invention.

Referring to FIG. 11, the foreign matter detection device 1100 includes a power supply unit 1101, a DC-DC converter 1102, an inverter 1103, a resonance capacitor 1104, a transmission coil 1105, It may include a quality factor measurement unit 1106, a demodulation unit 1107, a modulation unit 1108, a sensing unit 1109, and a control unit 1110.

The power supply unit 1101 may receive DC power through an external power terminal and transmit it to the DC-DC converter 1102 .

The DC-DC converter 1102 may convert the intensity of DC power received from the power supply unit 1101 into DC power of a specific intensity under the control of the controller 1110 . For example, the DC-DC converter 1102 may be configured as a variable voltage device capable of adjusting the intensity of voltage, but is not limited thereto.

The inverter 1103 may convert the converted DC power into AC power. The inverter 1103 may convert a DC power signal input through control of a plurality of switches into an AC power signal and output the converted AC power signal.

For example, the inverter 1103 may include a full bridge circuit, but is not limited thereto, and may include a half bridge.

As another example, the inverter 1103 may include both a half bridge circuit and a full bridge circuit. In this case, the control unit 1110 determines whether the inverter 1103 operates as a half bridge or a full bridge. can also be determined.

The wireless power transmitter according to an embodiment of the present invention may adaptively control the bridge mode of the inverter 1103 according to the intensity of power required by the wireless power receiver. For example, when the wireless power receiver requires low power of 5 W, the controller 1110 may control the half bridge circuit of the inverter 1103 to be driven.

On the other hand, when the wireless power receiver requires high power of 15 W, the controller 1110 may control the full bridge circuit to be driven.

As another example, the wireless power transmitter may adaptively select and drive a full-bridge circuit or a half-bridge circuit according to the detected temperature. For example, when the temperature of the wireless power transmitter exceeds a predetermined reference value while transmitting wireless power using the half-bridge circuit, the controller 1110 may deactivate the half-bridge circuit and activate the full-bridge circuit. That is, the wireless power transmission device can lower the temperature of the wireless power transmission device below the reference value by increasing the voltage through the full bridge circuit and reducing the intensity of the current flowing through the transmission coil 1105 for power transmission of the same intensity. there is. In general, the amount of heat generated in an electronic component mounted in an electronic device may be more sensitive to the intensity of current than the intensity of voltage applied to the corresponding electronic component.

In addition, the inverter 1103 can convert DC power into AC power as well as change the intensity of AC power.

For example, the inverter 1103 may adjust the intensity of output AC power by adjusting the frequency of a reference alternating current signal used to generate AC power under the control of the controller 1110 . To this end, the inverter 1103 may include a frequency oscillator that generates a reference AC signal having a specific frequency, but this is only one embodiment, and another example is that the frequency oscillator is separate from the inverter 1103. It can also be configured and installed.

The quality factor measuring unit 1106 may monitor a change in inductance (or voltage or current) value of both ends of the resonant capacitor 1104 to measure the quality factor value of the transmission coil of the corresponding wireless power transmission device. At this time, the measured current quality factor value is transmitted to the controller 1110, and the controller 1110 may store the measured current quality factor value received from the quality factor measurement unit 1106 in a predetermined recording area.

For example, the controller 1110 may measure the quality factor value in the selection steps 410 and 510 of FIGS. 4 and 5 described above. The control unit 1110 controls the Foreign Object Detection Quality Factor Threshold Value (FOD_QFT_Value) to determine whether a foreign object exists based on the Reference Quality Factor Value (RQF_Value) received from the wireless power receiver. ) can be determined. The controller 1110 may compare the measured quality factor values (Measured_Quality_Factor_Value, MQF_Value) with FOD_QFT_Value to perform a foreign matter detection procedure based on the quality factor value to determine whether a foreign material exists.

Here, RQF_Value may be determined as a value having the smallest value among quality factor values measured at a plurality of points on a charging area of a specific wireless power transmitter designated for performance testing.

FOD_QFT_Value may be determined by subtracting reference quality factor accuracy and production and measurement errors from RQF_Value.

Here, the criterion quality factor accuracy may be an allowable range of error with respect to the criterion quality factor value measured when the foreign material does not exist. For example, the reference quality factor value to which the tolerance range of error is applied may be set at a rate of increase or decrease relative to the reference quality factor value received from the wireless power receiver, but is not limited thereto.

The current WPC Qi standard defines the same criterion quality factor accuracy for all products.

However, the reference quality factor accuracy may have different values depending on the manufacturer of the corresponding product and the type of product. For example, the wireless power receiver of company A and the wireless power receiver of company B may measure the reference quality factor value in association with the same wireless power transmitter. However, the accuracy of the measured reference quality factor values for the two products may differ from each other. Therefore, the FOD_QFT_Value for determining the presence or absence of a foreign material determined based on the accuracy of the different reference quality factors for each wireless power receiver may not be an accurate threshold value for determining the presence or absence of a foreign material.

As an example, as a test result for the same wireless power transmitter, the value of the standard quality factor measured for the wireless power receiver of company A may be 100, and the value of the standard quality factor measured for the wireless power receiver of company B may be 70. In this case, the reference quality factor accuracy corresponding to company B's wireless power receiver is +/- 7%, and the reference quality factor accuracy corresponding to company A's wireless power receiver is set to +/- 10%, which is +/- 10 for both companies. Compared to setting in %, the probability of detecting foreign matter more accurately may increase. However, since the same criterion quality factor accuracy is applied to all wireless power receivers during the FOD certification test according to the current WPC Qi standard, there is a problem in that an accurate FOD certification test cannot be performed.

The demodulator 1107 demodulates the in-band signal received from the wireless power receiver and transmits it to the controller 1110. For example, the demodulator 1107 may demodulate and transmit the FOD status packet of FIG. 12 and the configuration packet of FIG. 13 to the control unit 1110, which will be described later. Here, the FOD status packet or the configuration packet may include a predetermined receiver type identifier for identifying the type and type of the wireless power receiver.

The controller 1110 may determine a predetermined current change threshold (Delta_Current_Threshold) for determining whether a foreign substance is present based on the received receiver type identifier. The controller 1110 may compare the amount of change in I_rail (Delta_RAIL_Current) measured in the ping step with the determined current change threshold to determine whether a foreign substance is present.

As an embodiment, when the receiver type identifier is included in the configuration packet and received, the controller 1110 may determine whether a foreign substance is present in the identification and configuration step 530 of FIG. 5 .

As another embodiment, when the receiver type identifier is included in the FOD status packet and received, the controller 1110 may determine whether a foreign substance exists in the negotiation step 540 of FIG. 5 .

If it is determined in the identification and configuration step 530 that a foreign substance is present, the controller 1110 may transition the state of the wireless power transmitter to the selection step 510 .

If it is determined in the negotiation step 540 that a foreign substance is present, the controller 1110 may allow the controller 1110 to enter the selection step 510 without entering the power transfer step 560 .

The modulator 1108 modulates the control packet received from the controller 1110 and transmits the modulated control packet through the transmission coil 1105 . For example, when the FOD status packet including the receiver type identifier is received, the control unit 1110 determines a current change threshold value corresponding to the corresponding receiver type identifier, and determines the measured current change amount of the inverter 1103 in the ping step - that is, , Delta_Rail_Current- and the determined current change threshold value, it is possible to finally determine the existence of foreign matter. Depending on the result of determining whether or not a foreign substance is present, the controller 1110 may generate an ACK packet or a NACK packet and transmit it to the modulator 1108 .

Here, the ACK packet may mean that the foreign matter has not been detected, and the NACK packet may mean that the foreign matter has been detected.

The controller 1110 according to another embodiment of the present invention may compare Delta_Rail_Current and Delta_Current_Threshold to determine whether a foreign substance is present, and then perform a foreign substance detection procedure based on the quality factor value. For convenience of description below, a procedure for determining the existence of a foreign substance by comparing Delta_Rail_Current with Delta_Current_Threshold will be referred to as a foreign substance detection procedure based on a change in current.

For example, the controller 1110 may finally determine that a foreign material exists when it is determined that a foreign material is present through both the foreign material detection procedure based on the amount of change in current and the foreign material detection procedure based on the quality factor value.

As another example, the controller 1110 may finally determine that a foreign material exists when it is determined that a foreign material is present in at least one of a foreign material detection procedure based on a change in current and a foreign material detection procedure based on a quality factor value. there is.

As another example, the controller 1110 may control to perform a foreign material detection procedure based on a change in current when it is determined that a foreign material exists through the foreign material detection procedure based on the quality factor value. In this case, the controller 1110 may finally determine that a foreign material is present only when it is determined that the foreign material is present through a foreign material detection procedure based on the amount of change in current.

As another example, when the controller 1110 receives the FOD status packet and cannot perform the foreign matter detection process based on the quality factor value, the controller 1110 performs only the foreign matter detection process based on the amount of current change to finally determine the presence or absence of the foreign matter. It should be noted that there may be At this time, when it is determined that a foreign substance exists, the controller 1110 does not enter the power transmission step 560 in the negotiation step 540 of FIG. You can control the means. For example, the notification means may include a beeper, an LED lamp, a vibration device, a liquid crystal display, and the like, but is not limited thereto.

The sensing unit 1109 may measure voltage, current, power, temperature, etc. at a specific node, specific part, or specific location of the wireless power transmission device.

For example, the sensing unit 1109 measures the current/voltage/power intensity or/and current/voltage/power intensity variation between the DC-DC converter 1102 and the inverter 1103, and transmits the measurement result to the control unit. (1110).

For convenience of explanation below, the current flowing between the DC-DC converter 1102 and the inverter 1103 is I_rail, the voltage applied to the output terminal of the DC-DC converter 1102 or the input terminal of the inverter 1103 is V_rail, and the DC-DC Power transmitted from the converter 1102 to the inverter 1103 is referred to as P_rail.

As another example, the sensing unit 1109 measures the intensity of the current flowing through the transmission coil 1105 - that is, the inductor - and the intensity of the voltage applied to both ends of the transmission coil 1105, and transmits the measurement result to the control unit 1110. may be forwarded to.

The control unit 1110 according to an embodiment of the present invention calculates the amount of change in the intensity (I_rail) of the current applied to the inverter 1103 based on the sensing information received from the sensing unit 1109 in the ping step, and calculates the current intensity The amount of change can be stored in a predetermined recording area.

The control unit 1110 may determine the possibility of foreign matter presence—that is, the probability—by comparing a pre-stored current intensity change amount with a predetermined current change threshold value in the identification and configuration step.

As a result of the determination, if it is determined that the presence of the foreign matter is high, the controller 1110 may adjust the accuracy of the reference quality factor to a certain level lower. For example, when it is determined that the possibility of foreign matter is high, the controller 1110 may determine the FOD_QFT_Value by adjusting the standard quality factor accuracy from +/-10% to +/-5%. Through this, the controller 1110 can improve the foreign matter detection accuracy when determining the presence or absence of foreign matter based on the quality factor value. On the other hand, as a result of the determination, if the possibility of existence of a foreign substance is low, the controller 1110 may determine the FOD_QFT_Value based on the accuracy of a predefined reference quality factor.

The controller 1110 may determine that a foreign substance exists when MQF_Value is smaller than FOD_QFT_Value. When a foreign substance exists, the controller 1110 may not enter the power transmission step 560 from the negotiation step 540 of FIG. 5 . At this time, the controller 1110 may control a predetermined notification means provided in the wireless power transmission device so that the user recognizes that a foreign substance exists in the charging area. Here, the notification means may include a beeper, an LED lamp, a vibration element, a liquid crystal display, and the like, but is not limited thereto.

When MQF_Value is greater than or equal to FOD_QFT_Value, the controller 1110 may determine that no foreign matter exists in the charging area. When there is no foreign substance present, the controller 1110 may enter a power transmission step and control power required by the wireless power transmission device to be transmitted.

In addition, the control unit 1110 according to another embodiment of the present invention measures the current value measured in the ping step - for example, the output current (I_rail) of the DC-DC converter or the current (I_coil) applied to the transmission coil 1105 ) may be compared with a predetermined reference current value. As a result of the comparison, if the measured current value is greater than the reference current value, it may be determined that the possibility of the presence of foreign substances is low. In this case, even if the FOD status packet is received in the negotiation step, the control unit 1110 may enter the power transmission step without proceeding with the foreign matter determination procedure based on the quality factor value.

Referring to FIG. 11, the inverter input current I_rail is DC power, and the current flowing through the transmission coil 1105 is AC current. In particular, in the ping step, the current input to the inverter 1103 is DC power having a constant level, but the output power of the inverter 1103 is AC power that is transmitted non-continuously at regular intervals. Therefore, the time average value of I_rail may be relatively larger than the time average value of I_coil. Therefore, judging the possibility of foreign matter based on the change in I_rail can significantly reduce the probability of error in judgment.

When a conductive foreign material, which is not a normal wireless power receiver, is located in the charging area of the wireless power transmitter, a mutual impedance value between the transmission coil and the foreign material approaches zero. At this time, the intensity of the current I_rail applied to the inverter 1103 is rapidly increased. Accordingly, the controller 1110 may determine the possibility of foreign matter by monitoring a change in the intensity of the current I_rail applied to the inverter 1103 in the ping step.

As described above, the wireless power transmission device according to the present invention determines the presence of foreign substances based on the amount of change in the current applied to the inductor in the ping step, and adaptively blocks power transmission according to the determination result. It has the advantage of minimizing equipment damage and power waste. In addition, the foreign matter detection device according to the present invention dynamically determines the current change threshold based on the type identifier corresponding to the corresponding wireless power receiver when performing the foreign matter detection procedure based on the current intensity change, thereby increasing the detection accuracy of the foreign matter There are advantages.

12 is a diagram for explaining the message structure of a FOD status packet according to the present invention.

Referring to FIG. 12, the FOD status packet message 1200 may have a length of 2 bytes, and includes a 6-bit Receiver Type Identifier (1201), a 2-bit long Mode (Mode, 1202) field, and It may be configured to include a 1-byte long reference quality factor value (Reference Quality Factor Value, 1203). Although the length of the receiver type identifier 1201 field is shown in FIG. 12 as being 6 bits, it should be noted that this is only one embodiment and may be configured to a size smaller than 6 bits according to the design of those skilled in the art. .

As shown in reference number 1204, when the mode 1202 field is set to binary '00', the reference quality factor value 1203 is determined by measuring the power of the wireless power receiver while the wireless power receiver is turned off. It can mean being recorded.

13 is a diagram for explaining the structure of a configuration packet according to an embodiment of the present invention.

As shown in reference number 1301 of FIG. 13, the message format of the configuration packet may have a length of 5 bytes, and includes a power class field, a maximum power field, and a power control field. , a count field, a window size field, a window offset field, and first to third reserved fields 1301 to 1303.

A power class assigned to a corresponding wireless power receiver may be recorded in the power class field.

In the maximum power field, an intensity value of maximum power that can be provided from a rectifier output terminal of the wireless power receiver may be recorded.

For example, when the power class is a and the maximum power is b, the maximum amount of power (Pmax) desired to be provided from the output terminal of the rectifier of the wireless power receiver may be calculated as (b/2)*10 ^a .

The power control field may be used to indicate which algorithm should be used for power control in the wireless power transmitter. For example, if the power control field value is 0, it means that the power control algorithm defined in the standard is applied, and if the power control field value is 1, it means that power control is performed according to the algorithm defined by the manufacturer.

The count field may be used to record the number of option configuration packets to be transmitted by the wireless power receiver in an identification and configuration step.

The window size field may be used to record the window size for average received power calculation. For example, the window size may be a positive integer value greater than 0 and having a unit of 4 ms.

In the window offset field, information for identifying a time from the end of the average received power calculation window to the start of transmission of the next received power packet may be recorded. For example, the window offset may be a positive integer value greater than 0 and having a unit of 4 ms.

The receiver type identifier described in FIGS. 11 and 12 may be recorded in at least one reserved field among the first to third reserved fields 1301 to 1303 of FIG. 13 and transmitted to the wireless power transmitter.

Here, the number of bits allocated for the receiver type identifier may have a different length according to a design by a person skilled in the art, and the number of bits is not limited.

14 is a receiver type identifier mapping table in which current change thresholds corresponding to receiver type identifiers are defined according to an embodiment of the present invention.

Referring to FIG. 14, the receiver type identifier field has a length of 6 bits and may range from 0 to 63.

As shown in FIG. 14, the current change threshold has a mA unit and can be defined so that 100 mA increases as the type identifier increases by 1, but this is only one embodiment, and the current change corresponding to the type identifier It should be noted that the threshold may be defined differently according to the design of those skilled in the art. For example, the current change threshold may be defined to increase by 50 mA as the type identifier increases by 1.

In addition, in the embodiment of FIG. 13 described above, the receiver type identifier field is described as having a length of 6 bits, but this is only one embodiment, and the length of the receiver type identifier field may be greater than or less than 6 bits. It should be noted that there may be

If, as a result of the preliminary experiment on the wireless power receiver A, the current change measured at the time when the wireless power receiver A is located in the charging area in the ping step is 600mA, the receiver type identifier corresponding to the wireless power receiver A is a binary number “000101” ” can be assigned. For example, the wireless power receiver may transmit the receiver type identifier allocated to the wireless power receiver to the wireless power transmitter through a configuration packet in a configuration and identification step. As another example, the wireless power receiver may transmit the receiver type identifier allocated thereto to the wireless power transmitter through the FOD status packet in the negotiation step.

15 is a receiver type identifier mapping table in which current change threshold ratios corresponding to receiver type identifiers are defined according to another embodiment of the present invention.

15, the receiver type identifier has a length of 2 bits, and the current change threshold ratio is the current value of the digital ping signal measured when the wireless power receiver is not placed on the charging area - or less, for convenience of explanation, The initial inverter input current value (Initial_Inverter_Input_Current_Value) can be defined as the change ratio of the current value of the digital ping signal measured after the wireless power receiver is placed on the charging area (Measured_Inverter_Input_Current_Value) - that is, the value of the inverter input current intensity - versus the business card. .

As an example, the current change rate in the ping step is

{(Measured_Inverter_Inpurt_Current_Value-Initial_Inverter_Input_Current_Value)/(Initial_Inverter_Input_Current_Value)}*100

can be calculated as If the current change ratio corresponding to a specific wireless power receiver is 80, the receiver type identifier corresponding to the wireless power receiver may be defined as a binary number “10” as shown in FIG. 15 .

In the embodiment of FIG. 15, the receiver type identifier has a length of 2 bits and the current change threshold ratio corresponding to each receiver type identifier has a range of 20%, but this is only one embodiment. , the length of the receiver type identifier and the allocation range of the current change threshold ratio corresponding to each receiver type identifier may be defined differently depending on the design and applied equipment and systems by those skilled in the art.

16 is a flowchart illustrating a method of detecting a foreign object in a wireless power transmission device according to an embodiment of the present invention.

Referring to FIG. 16 , the wireless power transmission device may measure the intensity of current applied to the inverter in the ping step and store information on the measured intensity of the inverter input current in a predetermined recording area (S1601).

The wireless power transmitter may receive a packet including a receiver type identifier (S1602). Here, the receiver type identifier may be received through the configuration packet in the configuration and identification step, but this is only one embodiment, and in another embodiment, the receiver type identifier may be received through the FOD status packet in the negotiation step. .

The wireless power transmission device may determine a current intensity threshold corresponding to the receiver type identifier (S1603). Here, the current intensity threshold may be determined by referring to the receiver type identifier mapping table described with reference to FIG. 14, but is not limited thereto.

The wireless power transmission device may compare the inverter input current intensity stored in step 1601 with the current intensity threshold to determine whether a foreign substance is present in the charging area (S1604). For example, when the inverter input current intensity exceeds the current intensity threshold, the wireless power transmission device may determine that a foreign substance is present in the charging area. On the other hand, if the inverter input current intensity is less than or equal to the current intensity threshold, it may be determined that no foreign matter exists in the charging area.

If it is determined that a foreign substance is present, the wireless power transmission apparatus may output a predetermined alarm signal indicating that a foreign substance has been detected and then enter the selection step 510 (S1605).

If it is determined that the foreign matter does not exist as a result of the determination in step 1604 described above, the wireless power transmission apparatus may enter a negotiation step or a power transmission step (S1606).

17 is a flowchart illustrating a method of detecting a foreign object in a wireless power transmission device according to another embodiment of the present invention.

Referring to FIG. 17 , the wireless power transmission device may measure the intensity of current input to the inverter in the ping step and store information on the measured intensity of inverter input current (Measured_I_Rail) in a predetermined recording area (S1701).

The wireless power transmission device provides information on the intensity of current input to the inverter in a state where an object is not detected - that is, information on the initial inverter input current value (Initial_Inverter_Input_Current_Value) - and the measured inverter input current value (Measured_Inverter_Input_Current_Value) in the ping step. The change rate of the inverter input current (I_rail) can be calculated using the information (S1702). Here, the rate of change of the inverter input current may be calculated as {(Measured_Inverter_Inpurt_Current_Value-Initial_Inverter_Input_Current_Value)/(Initial_Inverter_Input_Current_Value)}*100.

The wireless power transmitter may receive a packet including a receiver type identifier (S1703). Here, the receiver type identifier may be received through the configuration packet in the configuration and identification step, but this is only one embodiment, and in another embodiment, the receiver type identifier may be received through the FOD status packet in the negotiation step. .

The wireless power transmission device may determine a current intensity threshold ratio corresponding to the receiver type identifier (S1704). Here, the current intensity threshold ratio may be determined by referring to the receiver type identifier mapping table described in FIG. 15, but is not limited thereto.

The wireless power transmission device may compare the change ratio of the inverter input current calculated in step 1702 with the current intensity threshold ratio determined in step 1704 to determine whether foreign substances exist in the charging area (S1705). For example, the wireless power transmission device may determine that a foreign material is present in the charging area when the change rate of the inverter input current exceeds the current intensity threshold rate. On the other hand, the wireless power transmission device may determine that there is no foreign material in the charging area when the change rate of the inverter input current is less than or equal to the current intensity threshold rate.

If it is determined that a foreign substance is present, the wireless power transmission device may output a predetermined alarm signal indicating that a foreign substance has been detected, and then proceed to selection step 510 (S1706).

If it is determined that the foreign matter does not exist as a result of the determination in step 1705 described above, the wireless power transmission apparatus may enter a negotiation step or a power transmission step (S1707).

18 is a flowchart illustrating a method of detecting a foreign material in a wireless power transmission device according to another embodiment of the present invention.

Referring to FIG. 18 , the wireless power transmitter may perform a foreign matter detection procedure based on the change in inverter input current intensity in the ping step (S1801).

The wireless power transmission device may determine whether a foreign substance is present through a foreign substance detection procedure based on a change in inverter input current intensity (S1802). As a result of the determination, when it is determined that the foreign matter exists, a foreign matter detection procedure based on the quality factor value may be performed in the negotiation step (S1803). At this time, the wireless power transmitter may correct the accuracy of the reference quality factor used to determine the quality factor threshold. For example, the accuracy of the reference quality factor may be adjusted from +/- 10% to +/- 5% to more accurately detect the foreign material.

The wireless power transmitter may determine whether a foreign material exists by performing a foreign matter detection procedure based on the quality factor value in the negotiation step (S1804). As a result of the determination, if a foreign substance exists, the wireless power transmission device may enter the selection step 510 after transmitting the NACK packet (S1805). On the other hand, as a result of the determination in step 1804 described above, if there is no foreign substance, the wireless power transmission device may start charging after transmitting an ACK packet (S1806) and entering the power transmission step (S1807).

In addition, as a result of the determination in step 1802 described above, when the foreign matter does not exist, the wireless power transmitter may perform step 1806 without performing the foreign matter detection procedure based on the quality factor value. In this case, after the FOD status packet is received in the negotiation step, the wireless power transmitter may generate an ACK packet and transmit it to the corresponding wireless power receiver.

19 is an embodiment of a transmission coil mounted in a wireless power transmission device according to an embodiment of the present invention.

Referring to FIG. 19 , the wireless power transmission device may be arranged so that three transmission coils overlap a certain area. As shown in FIG. 19, when a foreign substance is located in Position 1, which is the center of the transmission coil block, and Position 2, which is 20 mm away from it, the intensity of the inverter input current changes as shown in FIGS. 20A and 20B to be described later. It can be. In Position 3, which is 40mm away from the center of the transmission coil block, there is a feature that the change in inverter input current is not large for all foreign substances.

20A to 20B are graphs showing measurement results of the inductor input current intensity and the transmission coil input current intensity for each position of the transmission coil according to FIG. 19 .

FIG. 20A shows measurement results of inverter input current intensity and transmission coil input current intensity according to the type of foreign matter in Position 1 of FIG. 19 .

20B , reference numeral 2002 shows measurement results of the inductor input current intensity and the transmitting coil input current intensity according to the foreign material type in Position 2 of FIG. 19 .

Referring to FIGS. 20A and 20B , it can be seen that the current intensity measured at Position 1 is greater than the current intensity measured at Position 2 as a whole.

In addition, referring to FIGS. 20A and 20B , it can be seen that when a ping is transmitted, the current measured in a state in which there is no foreign substance is greater than the current measured in a state in which a foreign substance is present.

In particular, it can be seen that, when the state is changed from a state in which there is no foreign substance to a state in which the foreign substance is present, the change in the intensity of the inverter input current is greater than the change in the intensity of the transmitting coil current.

21 and 22 show a change pattern of coil current and inverter input current when a foreign material is located in the charging area in the ping step in Position 1 of FIG. 19 .

21 shows the case where the foreign material is a 10 won coin, and FIG. 22 shows the experimental results when the foreign material is a 500 won coin.

In the graph shown in FIG. 21, the amount of change in the coil current and inverter input current at the first ping transmission time when the foreign material is not located in the charging area is several tens of mA, but at the second ping transmission time when the foreign material is located in the charging area The variation of coil current and inverter input current is shown to be hundreds of mA.

Referring to FIG. 22 , when the foreign material is 500 won, changes in coil current and inverter input current are thousands of mA at the time of second ping transmission when the foreign material is located in the charging area.

The methods according to the above-described embodiments may be produced as programs to be executed on a computer and stored in a computer-readable recording medium. Examples of the computer-readable recording medium include ROM, RAM, CD-ROM, and magnetic tape. , floppy disks, optical data storage devices, and the like, and also includes those implemented in the form of carrier waves (for example, transmission through the Internet).

The computer-readable recording medium is distributed to computer systems connected through a network, so that computer-readable codes can be stored and executed in a distributed manner. In addition, functional programs, codes, and code segments for implementing the above-described method can be easily inferred by programmers in the technical field to which the embodiment belongs.

It is apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit and essential characteristics of the present invention.

Accordingly, the above detailed description should not be construed as limiting in all respects and should be considered illustrative. The scope of the present invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are included in the scope of the present invention.

Claims (21)

A foreign material detection method in a wireless power transmitter,
measuring the intensity of current input to the inverter in the ping step;
Receiving a packet including a receiver type identifier;
determining a threshold for the strength of the current corresponding to the receiver type identifier;
comparing the measured current intensity with a threshold value for the current intensity to determine whether a foreign substance is present; and
As a result of the determination, if the foreign matter exists, performing a foreign matter detection procedure based on the quality factor value;
When it is determined that a foreign substance exists through a foreign substance detection procedure based on the quality factor value, a NACK packet is transmitted to a corresponding wireless power receiver,
A foreign material detection method for transmitting an ACK packet to a corresponding wireless power receiver when it is determined that the foreign material does not exist through a foreign material detection procedure based on the quality factor value. delete delete delete delete delete delete delete According to claim 1,
If the foreign matter does not exist as a result of the determination, the foreign matter detection method further comprising the step of transmitting an ACK packet to a corresponding wireless power receiver after receiving the FOD status packet in the negotiation step. A foreign material detection method in a wireless power transmitter,
Calculating a rate of change of current input to the inverter in the ping step;
Receiving a packet including a receiver type identifier;
determining a threshold rate for a change in current corresponding to the receiver type identifier;
comparing the calculated rate of change of the current with a threshold rate of change of the current to determine whether a foreign substance is present; and
As a result of the determination, if the foreign matter exists, performing a foreign matter detection procedure based on the quality factor value;
When it is determined that a foreign substance exists through a foreign substance detection procedure based on the quality factor value, a NACK packet is transmitted to a corresponding wireless power receiver,
A foreign material detection method for transmitting an ACK packet to a corresponding wireless power receiver when it is determined that the foreign material does not exist through a foreign material detection procedure based on the quality factor value. According to claim 10,
The change rate of the current input to the inverter is calculated as the change ratio of the inverter input current intensity value measured in the ping step to the current intensity value input to the initial inverter in a state where the object is not detected. According to claim 10,
The step of determining whether the foreign matter exists
determining that a foreign substance is present when the calculated rate of change of the current exceeds a threshold rate for the change of the current; and
and determining that a foreign material does not exist when the calculated rate of change of the current is less than or equal to a threshold rate for the change of the current. The method of claim 1 or 10,
The receiver type identifier is included in a configuration packet in the configuration and identification step and received in a foreign object detection (FOD) status packet in the negotiation step. delete delete The method of claim 1 or 10,
As a result of the determination, if the foreign matter does not exist, the foreign matter detection method enters the negotiation step or the power transmission step. delete In the foreign matter detection device,
a sensing unit for measuring the intensity of current input to the inverter in the ping step;
a demodulator for receiving a packet including a receiver type identifier; and
A control unit determining a threshold value for the intensity of the current corresponding to the receiver type identifier and comparing the measured current intensity with the threshold value for the intensity of the current to determine whether a foreign substance is present,
The control unit,
As a result of the determination, if a foreign substance exists, a foreign substance detection procedure based on the quality factor value is performed,
When it is determined that a foreign substance exists through a foreign substance detection procedure based on the quality factor value, a NACK packet is transmitted to a corresponding wireless power receiver,
A foreign material detection device for transmitting an ACK packet to a corresponding wireless power receiver when it is determined that the foreign material does not exist through a foreign material detection procedure based on the quality factor value. In the foreign matter detection device,
a sensing unit for measuring a rate of change of current input to the inverter in the ping step;
a demodulator for receiving a packet including a receiver type identifier; and
In conjunction with the sensing unit, a rate of change of current input to the inverter is calculated, a threshold rate of change of current corresponding to the receiver type identifier is determined, and a rate of change of current and a threshold of change of current are determined. Including; a control unit that compares the ratio to determine the presence or absence of foreign matter;
The control unit,
As a result of the determination, if a foreign substance exists, a foreign substance detection procedure based on the quality factor value is performed,
When it is determined that a foreign substance exists through a foreign substance detection procedure based on the quality factor value, a NACK packet is transmitted to a corresponding wireless power receiver,
A foreign material detection device for transmitting an ACK packet to a corresponding wireless power receiver when it is determined that the foreign material does not exist through a foreign material detection procedure based on the quality factor value.
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