KR102633453B1 - Foreign Object Detection Method and Apparatus therefor - Google Patents

Abstract

The present invention relates to a method for detecting foreign matter for wireless charging and a device therefor. According to an embodiment of the present invention, a method for detecting foreign matter in a wireless power transmitter that transmits wireless power to a wireless power receiver includes receiving power from the wireless power receiver. Receiving information about the power intensity, determining whether the received power intensity is normal, and if the received power intensity is not normal as a result of the determination, correcting the received power intensity, and the corrected received power intensity It may include calculating a path loss for transmitted power based on and detecting a foreign substance based on the calculated path loss. Therefore, the present invention has the advantage of being able to detect foreign substances more accurately.

Description

Foreign object detection method and apparatus therefor {Foreign Object Detection Method and Apparatus therefor}

The present invention relates to wireless power transmission technology, and more specifically, to a foreign matter detection method and device capable of detecting foreign matter present on a wireless power transmission path.

Recently, as information and communication technology has developed rapidly, a ubiquitous society based on information and communication technology is being created.

In order for information and communication devices to be connected anytime, anywhere, sensors with computer chips with communication functions must be installed in all social facilities. Therefore, the problem of power supply to these devices and sensors is becoming a new challenge. Additionally, as the number of mobile devices, including not only mobile phones but also Bluetooth handsets and music players such as iPods, has rapidly increased, charging the battery has become more time-consuming and labor-intensive for users. Wireless power transmission technology has recently been receiving attention as a way to solve these problems.

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

To date, energy transfer methods using wireless can be broadly divided into magnetic induction, electromagnetic resonance, and RF transmission using short-wavelength radio frequencies.

The magnetic induction method is a technology that uses the phenomenon of placing two coils adjacent to each other and sending current through one coil, and the resulting magnetic flux generates electromotive force in the other coil. It is rapidly commercialized mainly in small devices such as mobile phones. is in progress. The magnetic induction method can transmit up to hundreds of kilowatts (kW) of power and has high efficiency, but the maximum transmission distance is less than 1 centimeter (cm), so it has the disadvantage of generally having to be placed close to a charger or the floor.

The magnetic resonance method has the characteristic of using electric or magnetic fields instead of using electromagnetic waves or currents. The magnetic resonance method has the advantage of being safe for other electronic devices and the human body because it is almost unaffected by electromagnetic wave problems. On the other hand, it has the disadvantage of being able to be used only at limited distances and spaces and having somewhat low energy transfer efficiency.

Short-wavelength wireless power transmission - simply RF transmission - takes advantage of the fact that energy can be transmitted and received directly in the form of radio waves. This technology is an RF wireless power transmission method using a rectenna. Rectenna is a compound word of antenna and rectifier and refers to an element that directly converts RF power into direct current power. In other words, the RF method is a technology that converts AC radio waves into DC, and as efficiency has recently improved, research on commercialization is actively underway.

Wireless power transmission technology can be used in a variety of industries, including mobile, IT, railway, and home appliance industries.

If 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 guided to the foreign object. As an example, FO may include coins, clips, pins, ballpoint pens, etc.

If an FO exists between the wireless power receiver and the wireless power transmitter, not only does the wireless charging efficiency decrease significantly, but the temperature of the wireless power receiver and the wireless power transmitter may also increase due to an increase in the temperature around the FO. If the FO located in the charging area is not quickly removed, power transmission efficiency may deteriorate, resulting in power waste, and may also cause damage to the device due to overheating.

Therefore, accurately detecting FOs located on the wireless power transmission path has emerged as an important issue in the field of wireless charging technology.

In the current wireless charging system that follows the standards of the Wireless Power Consocium (WPC), representative methods for detecting foreign substances placed in the charging area include a method based on the path loss of transmitted power and a method based on changes in quality factor value. It is being used.

However, in the case of a foreign matter detection method based on the path loss of transmitted power, there is a problem in that foreign matter detection fails when the wireless power transmitter does not receive accurate received power intensity information from the wireless power receiver.

The present invention was designed to solve the problems of the prior art described above. The purpose of the present invention is to provide a foreign matter detection method and device capable of detecting foreign matter present on a wireless power transmission path.

Another object of the present invention is to provide a method and device for detecting foreign substances capable of adaptively correcting a threshold value (or threshold range) for detecting foreign substances based on whether the received power intensity is normal or not.

Another object of the present invention is to provide a foreign matter detection method and device capable of detecting foreign matter by correcting path loss when a receiver is identified in which the intensity of received power relative to the intensity of transmitted power is abnormal in a fixed frequency wireless power transmitter. will be.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, 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 method for detecting foreign substances and a device therefor.

A method of detecting foreign matter in a wireless power transmitter that transmits wireless power to a wireless power receiver according to an embodiment of the present invention includes the steps of receiving information about the received power intensity from the wireless power receiver and determining whether the received power intensity is normal. determining, and if the received power intensity is not normal as a result of the determination, correcting the received power intensity, calculating a path loss for the transmitted power based on the corrected received power intensity, and the calculated path It may include detecting foreign substances based on loss.

Here, the information about the received power intensity is received in a packet that is periodically fed back in the power transmission stage, and the fed back packet may be a signal intensity packet defined in the WPC standard.

For example, the step of determining whether the received power intensity is normal includes determining a first threshold indicating the maximum received signal intensity that can be received by the wireless power receiver in response to the intensity of the current transmitted power, and the received power intensity. If exceeds the first threshold, it may include determining that the received power intensity is not normal.

As another example, the step of determining whether the received power intensity is normal includes determining a first threshold range indicating a power level that can be received by the wireless power receiver based on the intensity of the current transmitted power and a predefined transmission efficiency. and if the received power intensity is outside the first threshold range, determining that the received power intensity is not normal.

In addition, the step of correcting the received power intensity may include determining an offset value based on the intensity of the current transmitted power and correcting the received power intensity by subtracting the offset value from the received power intensity. .

In addition, the step of detecting the foreign matter may include determining a path loss threshold based on the intensity of the current transmission power, and if the calculated path loss exceeds the path loss threshold, the foreign matter may be present on the transmission path of the wireless power. It may include a step of determining that this exists.

In addition, the foreign matter detection method further includes receiving a feedback signal for power control in the power transmission step, and the intensity of the currently transmitted power may be adjusted based on the feedback signal.

In addition, in the foreign matter detection method, when a foreign matter detection status packet containing a standard quality factor value is received in the step of measuring the quality factor value and the negotiation step after detecting the object and before entering the ping step, the foreign material detection status packet is received based on the standard quality factor value. The method may further include determining a quality factor threshold value corresponding to the second wireless power receiver and detecting a foreign substance by comparing the measured quality factor value with the determined quality factor value.

A wireless power transmitter that transmits wireless power to a wireless power receiver according to another embodiment of the present invention receives a first packet for power control and a first packet containing information about the received power intensity from the wireless power receiver. a demodulator for determining whether the received power intensity is normal; a correction unit for correcting the received power intensity if the received power intensity is not normal as a result of the determination; and transmitting based on the corrected received power intensity. It may include a detection unit that detects foreign substances by calculating path loss for power.

Here, the first packet and the second packet are received periodically, and the wireless power transmitter may further include an adjuster that adjusts the intensity of the transmitted power based on the first packet.

Additionally, the first packet and the second packet may be a control error packet and a signal strength packet, respectively, defined in the WPC standard.

As an example, the determination unit determines a first threshold indicating the maximum received signal strength that can be received by the wireless power receiver based on the strength of the current transmission power adjusted by the control unit, and the received power strength is the first threshold value. If it exceeds the 1 threshold, it may be determined that the received power intensity is not normal.

As another example, the determination unit determines a first threshold range indicating a power level that can be received by the wireless power receiver based on the intensity of the current transmission power adjusted by the control unit and a predefined transmission efficiency, and the reception If the power intensity is outside the first threshold range, it may be determined that the received power intensity is not normal.

Additionally, the correction unit may determine an offset value based on the intensity of the current transmitted power and correct the received power intensity by subtracting the offset value from the received power intensity.

In addition, the detection unit determines a path loss threshold based on the intensity of the current transmission power, and when the calculated path loss exceeds the path loss threshold, it is determined that a foreign substance exists on the transmission path of the wireless power. can do.

In addition, when the wireless power transmitter receives a foreign object detection status packet containing a standard quality factor value in the negotiation stage with the measuring unit that measures the quality factor value after detecting the object and before entering the ping stage, it responds to the standard quality factor value. It may further include a control unit that determines a quality factor threshold value corresponding to the second wireless power receiver based on the quality factor value, and detects foreign matter by comparing the measured quality factor value with the determined quality factor value.

Another embodiment of the present invention may provide a computer-readable recording medium on which a program for executing any one of the above foreign matter detection methods is recorded.

The above aspects of the present invention are only some of the preferred embodiments of the present invention, and various embodiments reflecting the technical features of the present invention will be described in detail by those skilled in the art. It can be derived and understood based on.

The effects of the method and device according to the present invention are explained as follows.

The present invention has the advantage of providing a foreign matter detection method and device capable of detecting foreign matter present on a wireless power transmission path.

In addition, the present invention has the advantage of providing a foreign matter detection method and a wireless power transmission device capable of adaptively correcting the threshold value (or threshold range) for detecting foreign matter based on whether the received power intensity is normal.

In addition, the present invention has the advantage of providing a foreign matter detection method and device capable of detecting foreign matter by correcting path loss when a receiver is identified in which the intensity of received power relative to the intensity of transmitted power is abnormal in a fixed-frequency wireless power transmitter. there is.

In addition, the present invention not only has the advantage of minimizing foreign matter detection errors, but can also be expected to minimize unnecessary power waste and equipment damage.

Additionally, the present invention has the advantage of being able to detect foreign substances even if an abnormal wireless power receiver is placed in the charging area.

The effects that can be obtained from 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.

Figure 1 is a block diagram for explaining a wireless charging system according to an embodiment of the present invention.
Figure 2 is a block diagram for explaining a wireless charging system according to another embodiment of the present invention.
Figure 3 is a diagram for explaining a detection signal transmission procedure in a wireless charging system according to an embodiment of the present invention.
Figure 4 is a state transition diagram for explaining a wireless power transmission procedure according to an embodiment of the present invention.
Figure 5 is a state transition diagram for explaining a wireless power transmission procedure according to another embodiment of the present invention.
Figure 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 linked with the wireless power transmitter of FIG. 6.
Figure 8 is a diagram for explaining a method of modulating and demodulating a wireless power signal according to an embodiment of the present invention.
Figure 9 is a diagram for explaining a packet format according to an embodiment of the present invention.
Figure 10 is a diagram for explaining types of packets according to an embodiment of the present invention.
Figure 11 is a diagram for explaining the structure of a foreign matter detection device according to an embodiment of the present invention.
Figure 12 is a diagram for explaining the message structure of the Foreign Object Detection Status Packet according to the present invention.
13 is a state transition diagram for explaining a method of detecting a foreign substance in a foreign substance detection device according to an embodiment of the present invention.
Figure 14 is a state transition diagram for explaining a method of detecting foreign matter in a foreign matter detection device according to another embodiment of the present invention.
Figure 15 is a flowchart for explaining a method for detecting foreign substances according to an embodiment of the present invention.
Figure 16 is a block diagram for explaining the configuration of a foreign matter detection device according to an embodiment of the present invention.

Hereinafter, devices 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 “part” for components used in the following description are given or used interchangeably only for the ease of preparing the specification, and do not have distinct meanings or roles in themselves.

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

In the description of the embodiment, signals transmitted and received between a wireless power transmission device and a wireless power reception device will be used interchangeably with packets.

In the description of the embodiment, a device equipped with a function for transmitting wireless power on a wireless charging system is a wireless power transmitter, a wireless power transmitting device, a wireless power transmitting device, a wireless power transmitter, a transmitting stage, a transmitter, and a transmitting device for convenience of explanation. , it is decided to use the transmitter, wireless power transmission device, and wireless power transmitter interchangeably. In addition, it is an expression for a device equipped with the function of receiving wireless power from a wireless power transmitting device. For convenience of explanation, it is referred to as a wireless power receiving device, a wireless power receiver, a wireless power receiving device, a wireless power receiver, a receiving terminal, a receiving side, Receiving devices, receivers, etc. may be used interchangeably.

The transmitter according to the present invention may be configured in the form of a pad, a holder, an Access Point (AP), a small base station, a stand, a ceiling-embedded form, a wall-mounted form, etc., and one transmitter can be connected to a plurality of wireless power receiving devices. Power can also be transmitted. To this end, the transmitter may be equipped with at least one wireless power transmission means. Here, the wireless power transmission means generates a magnetic field in the power transmitting end coil and charges using the electromagnetic induction principle in which electricity is induced in the receiving end coil under the influence of the magnetic field. Various wireless power transmission standards based on electromagnetic induction can be used. Here, the wireless power transmission means may include electromagnetic induction wireless charging technology defined by WPC (Wireless Power Consortium) and PMA (Power Matters Alliance), which are wireless charging technology standard organizations.

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

The receiver according to the present invention is used in mobile phones, smart phones, laptop computers, digital broadcasting terminals, PDAs (Personal Digital Assistants), PMPs (Portable Multimedia Players), navigation, MP3 players, and electric It can be used in 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 to this, and is not limited to any device equipped with a wireless power receiving means according to the present invention and capable of charging a battery. It's enough.

Figure 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 largely consists of a wireless power transmitter 10 that transmits power wirelessly, a wireless power receiver 20 that receives the transmitted power, and an electronic device 20 that receives the received power. It can be configured.

For example, the wireless power transmitter 10 and the wireless power receiver 20 may perform in-band communication to exchange information using the same frequency band as the operating frequency used for wireless power transmission. As another example, the wireless power transmitting end 10 and the wireless power receiving end 20 perform out-of-band communication in which information is exchanged using a separate frequency band different from the operating frequency used for wireless power transmission. It can also be done.

As an example, information exchanged between the wireless power transmitting end 10 and the wireless power receiving end 20 may include not only each other's status information but also control information. Here, the status information and control information exchanged between the transmitting and receiving ends will become clearer through descriptions of embodiments to be described later.

The in-band communication and out-of-band communication may provide two-way communication, but are not limited thereto, and in other embodiments, one-way communication or half-duplex communication may be provided.

As an example, one-way communication may be where the wireless power receiving end 20 transmits information only to the wireless power transmitting end 10, but is not limited to this, and the wireless power transmitting end 10 transmits information to the wireless power receiving end 20. It may be transmitting .

The half-duplex communication method allows two-way communication between the wireless power receiving end 20 and the wireless power transmitting end 10, but has the characteristic of allowing information to be transmitted only by one device at any one time.

The wireless power receiving end 20 according to an embodiment of the present invention may obtain various state information of the electronic device 30. As an example, the status information of the electronic device 30 may include, but is limited to, current power usage information, information for identifying running applications, CPU usage information, battery charging state information, and battery output voltage/current information. This does not apply, and information that can be obtained from the electronic device 30 and used for wireless power control is sufficient.

In particular, the wireless power transmitter 10 according to an embodiment of the present invention may transmit a packet indicating whether to support fast charging to the wireless power receiver 20. If it is confirmed that the connected wireless power transmitting end 10 supports the fast charging mode, the wireless power receiving end 20 may notify the electronic device 30 of this. The electronic device 30 may display that fast charging is possible through a provided display means (for example, it may be a liquid crystal display).

Additionally, 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 means. 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 receiving end 20. The wireless power receiving end 20 generates a charging mode packet corresponding to the received fast charging request signal and transmits it to the wireless power transmitting end 10, thereby converting the general low-power charging mode to the fast charging mode.

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

As an example, as shown in reference numeral 200a, the wireless power receiving terminal 20 may be composed of a plurality of wireless power receiving devices, and a plurality of wireless power receiving devices are connected to one wireless power transmitting terminal 10 to wirelessly transmit power. 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 to this. 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 receiving devices that can be connected to one wireless power transmitting device 10 depends on at least one of the amount of power required for each wireless power receiving device, the battery charging state, the power consumption of the electronic device, and the available power amount of the wireless power transmitting device. It can be determined adaptively based on

As another example, as shown in reference numeral 200b, the wireless power transmission terminal 10 may be composed of a plurality of wireless power transmission devices. In this case, the wireless power receiving end 20 can be connected to a plurality of wireless power transmitting devices at the same time, and can also perform charging by simultaneously receiving power from the connected wireless power transmitting devices. At this time, the number of wireless power transmitting devices connected to the wireless power receiving terminal 20 is adaptively adjusted based on the required power amount of the wireless power receiving terminal 20, battery charging status, power consumption of electronic devices, and available power amount of the wireless power transmitting device. can be decided.

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

As an example, a wireless power transmitter may be equipped with three transmission coils 111, 112, and 113. Each transmitting coil may overlap in some areas with other transmitting coils, and the wireless power transmitter may generate predetermined detection signals 117 and 127 for detecting the presence of the wireless power receiver through each transmitting coil - for example, Digital ping signals are sequentially transmitted 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 drawing number 110, and receives a signal strength signal (Signal) from the wireless power receiver 115. The transmitting coils 111 and 112 through which the strength signal 116) is received can be identified. Here, the signal strength signal may include information about the signal strength measured by the wireless power receiver 115 in response to the corresponding detection signal - hereinafter referred to as a signal strength indicator for convenience of description.

Subsequently, the wireless power transmitter sequentially transmits the detection signal 127 through the secondary detection signal transmission procedure shown in drawing number 120, and transmits power among the transmission coils 111 and 112 where the signal strength signal 126 is received. It is possible to identify a transmitting coil with good efficiency (or charging efficiency) - that is, the alignment between the transmitting coil and the receiving coil - and control it so that power is transmitted through the identified transmitting coil - that is, wireless charging occurs. .

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

If the signal strength indicators 116 and 126 are received at the first transmission coil 111 and the second transmission coil 112, as shown in drawing numbers 110 and 120 of FIG. 3, the wireless power transmitter Selects the best aligned transmitting coil based on the signal strength signal 126 received by each of the first transmitting coil 111 and the second transmitting coil 112, and performs wireless charging using the selected transmitting coil. .

Figure 4 is a state transition diagram for explaining a wireless power transmission procedure according to an embodiment of the present invention.

Referring to FIG. 4, the state of the wireless power transmitter for wireless power transmission is largely divided into a selection phase (Selection Phase, 410), a ping phase (Ping Phase, 420), an identification and configuration phase (Identification and Configuration Phase, 430), and power. It can be divided into a transmission phase (Power Transfer Phase, 440).

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

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 wireless charging standard. If the transmitter does not receive a response signal to the digital ping - for example, a signal strength signal - from the receiver in the ping step 420, it may transition back to the selection step 410 (S402). Additionally, when the transmitter receives a signal indicating that power transmission has been completed from the receiver in the ping step 420 - that is, a charging completion signal - it may transition to the selection step 410 (S403).

Once the ping step 420 is completed, the transmitter may transition to the identification and configuration step 430 to identify the receiver and collect receiver configuration and status information (S404).

In the identification and configuration step 430, the transmitter detects that an undesired packet is received (unexpected packet), a desired packet is not received for a predefined period of time (time out), there is a packet transmission error (transmission error), or a power transmission agreement is reached. If this is not set (no power transfer contract), it can transition to the selection step 410 (S405).

Once the identification and configuration of the receiver is completed, the transmitter may transition to the power transmission step 240, in which wireless power is transmitted (S406).

In the power transmission step 440, the transmitter receives an undesired 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 transfer contract violation), when charging is completed, the process can proceed to the selection step (410) (S407).

Additionally, in the power transmission step 440, the transmitter may transition to the identification and configuration step 430 if there is a need to reconfigure the power transmission contract according to a change in transmitter status, etc. (S408).

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

Figure 5 is a state transition diagram for explaining the wireless power transfer procedure.

Referring to FIG. 5, power transmission from a transmitter to a receiver according to an embodiment of the present invention largely consists of a selection phase (510), a ping phase (520), and an identification and configuration phase (Identification and Configuration Phase). , 530), negotiation phase (Negotiation Phase, 540), calibration phase (Calibration Phase, 550), power transfer phase (Power Transfer Phase, 560), and renegotiation phase (Renegotiation Phase, 570).

The selection phase 510 may be a transition phase - e.g., including reference numerals S502, S504, S508, S510, S512 - if a specific error or specific event is detected while starting or maintaining power transfer. You can. Here, specific errors and specific events will become clear through the following description. Additionally, in selection step 510, the transmitter may monitor whether an object is present on the interface surface. If the transmitter detects that an object has been placed on the interface surface, it may transition to the ping step 520. In the selection step 510, the transmitter transmits a very short pulse analog ping signal, and an object is detected in the active area of the interface surface based on the current change in the transmitting coil or primary coil. It is possible to detect the presence of .

If an object is detected in selection step 510, the wireless power transmitter may measure the quality factor of a wireless power resonance circuit, for example, a transmitting coil and/or resonance capacitor for wireless power transmission.

The wireless power transmitter can measure the inductance of a wireless power resonance circuit (eg, a power transmission coil and/or a resonance capacitor).

The detailed measurement method will be explained through other drawings instead.

The quality factor and/or inductance may be used to determine whether foreign matter is present in a future negotiation step 540.

In the ping step 520, when an object is detected, the transmitter wakes up the receiver and transmits a digital ping to identify whether the detected object is a wireless power receiver (S501). If the transmitter does not receive a response signal to the digital ping - for example, a signal strength packet - from the receiver in the ping step 520, it may transition back to the selection step 510. Additionally, when the transmitter receives a signal indicating that power transmission has been completed from the receiver in the ping step 520 - that is, a charging completion packet - it may transition to the selection step 510 (S502).

Once the ping step 520 is completed, the transmitter may transition to the identification and configuration step 530 to identify the receiver and collect receiver configuration and status information (S503).

In the identification and configuration step 530, the transmitter detects that an undesired packet is received (unexpected packet), a desired packet is not received for a predefined time (time out), there is a packet transmission error (transmission error), or a power transmission contract is entered. If this is not set (no power transfer contract), the process may transition to the selection step 510 (S504).

The transmitter can determine whether entry into the negotiation step 540 is necessary based on the negotiation field value of the configuration packet received in the identification and configuration step 530.

As a result of the confirmation, if negotiation is necessary, the transmitter can enter the negotiation step 540 (S505). In negotiation step 540, the transmitter may perform certain FOD detection procedures.

On the other hand, if negotiation is not necessary as a result of confirmation, the transmitter may immediately enter the power transmission step 560 (S506).

In the negotiation step 540, the transmitter may receive a Foreign Object Detection (FOD) status packet containing a reference quality factor value. Alternatively, an FOD status packet containing a reference inductance value may be received. Alternatively, a status packet containing a reference quality factor value and a reference inductance value may be received. At this time, the transmitter may determine a quality factor threshold for FO detection based on the reference quality factor value. The transmitter may determine the inductance threshold for FO detection based on the reference inductance value.

The transmitter may detect the presence of FO in the charging area using the determined quality factor threshold for FO detection and the currently measured quality factor value (which may be, for example, a quality factor value measured prior to the ping step), and the FO Power transmission can be controlled according to the detection results. As an example, if FO is detected, power transmission may be stopped, but is not limited to this.

The transmitter may detect the presence of FO in the charging area using the determined inductance threshold for FO detection and the currently measured inductance value (which may, for example, be the inductance value measured prior to the ping step), and add the FO detection result to the FO detection result. Power transmission can be controlled accordingly. As an example, if FO is detected, power transmission may be stopped, but is not limited to this.

If FO is detected, the transmitter may return to selection step 510 (S508). On the other hand, if FO is not detected, the transmitter may go through the correction step 550 and enter the power transmission step 560 (S507 and S509). In detail, if FO is not detected, the transmitter determines the strength of the power received at the receiving end in the correction step 550, and calculates the power loss at the receiving end and the transmitting end to determine the strength of the power transmitted from the transmitting end. It can be measured. That is, in the correction step 550, the transmitter can predict power loss based on the difference between the transmit power of the transmitter and the receive power of the receiver. The transmitter according to one embodiment may correct the threshold for FOD detection by reflecting the predicted power loss.

In the power transfer step 560, the transmitter receives an undesired packet (unexpected packet), a desired packet is not received for a predefined time (time out), or a violation of a preset power transfer contract occurs (power transfer contract violation), when charging is completed, the process can transition to the selection step (510) (S510).

Additionally, in the power transmission step 560, if the transmitter needs to reconfigure the power transmission contract according to a change in the transmitter state, etc., the transmitter may transition to the renegotiation step 570 (S511). At this time, if the renegotiation is completed normally, the transmitter may return to the power transmission step 560 (S513).

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

If renegotiation is not completed normally, the transmitter may stop transmitting power to the corresponding receiver and transition to the selection step (510) (S512).

Figure 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 largely 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 is not necessarily an essential configuration, and may include more or fewer components.

As shown in FIG. 6, when DC power is supplied from the power supply unit 660, the power conversion unit 610 may perform the function of converting it into AC power of a predetermined strength.

To this end, the power converter 610 may be configured to include a DC/DC converter 611, an inverter 612, and a frequency generator 613. Here, the inverter 612 may be a half-bridge inverter or a full-bridge inverter, but is not limited thereto, and any circuit configuration that can convert direct current power into alternating current power with a specific operating frequency is sufficient.

The DC/DC converter 611 may perform the 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.

At this time, the sensing unit 650 can measure the voltage/current, etc. of the DC converted power and provide it to the control unit 640.

Additionally, 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.

As an example, the control unit 640 may adaptively block the power supply from the power unit 650 or block power from being supplied to the amplifier 612 based on the voltage/current value measured by the sensing unit 650. You can. To this end, a power blocking 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 to block the power supplied to the amplifier 612.

The inverter 612 may convert the DC/DC converted direct current power into alternating current power based on the reference alternating current signal generated by the frequency generator 613. At this time, the frequency of the reference alternating current signal - that is, the operating frequency - may be dynamically changed according to the control signal from the control unit 640. The wireless power transmitter 600 according to an embodiment of the present invention may adjust the intensity of transmitted power by adjusting the operating frequency. As an example, the control unit 640 may receive power reception status information or/and a power control signal of the wireless power receiver through the communication unit 630, based on the received power reception status information or/and power control signal. Thus, the operating frequency can be determined, and the frequency generator 613 can be dynamically controlled so that the determined operating frequency is generated. As an example, the power reception status information may include information on the intensity of the rectifier output voltage, information on the intensity of the current applied to the 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, etc.

The power transmission unit 620 may include a multiplexer 621 (or multiplexer) and a transmission coil unit 622. Here, the transmitting coil unit 622 may be composed of first to nth transmitting coils. Additionally, the power transmission unit 620 may further include a carrier wave generator (not shown) for generating a specific carrier frequency for power transmission. In this case, the carrier generator may generate an AC signal with a specific carrier frequency for mixing with the output AC power of the inverter 612 received through the multiplexer 621. It should be noted that in one embodiment of the present invention, the frequency of AC power delivered to each transmission coil may be different. Another embodiment of the present invention may set the resonance frequency for each transmission coil to be different using a predetermined frequency controller equipped with a function to differently adjust the LC resonance characteristics for each transmission coil.

The multiplexer 621 may perform a switch function to transfer AC power to the transmission coil selected by the control unit 640. The control unit 640 may select a transmitting coil to be used for power transmission to the corresponding wireless power receiver based on the signal strength indicator received for each transmitting coil.

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 - that is, first to third wireless power receivers - are identified in the wireless power transmitter 600 through three different transmitting coils - that is, first to third transmitting coils. , the control unit 640 can control the multiplexer 621 so that AC power can be transmitted only through a specific transmission coil at a specific time slot. At this time, the amount of power transmitted to the wireless power receiver may be controlled depending on the length of the time slot allocated to each transmitting coil, but this is only one embodiment, and another example is during the time slot allocated to each transmitting coil. The intensity of the output direct current power of the DC/DC converter 611 can be controlled to control the transmission power of each wireless power receiver.

The control unit 640 may control the multiplexer 621 so that detection signals are sequentially transmitted through the first to nth transmission coils 622 during the first detection signal transmission procedure. At this time, the control unit 640 can identify the time when the detection signal will be transmitted using the timer 655, and when the detection signal transmission time arrives, it controls the multiplexer 621 to transmit the detection signal through the corresponding transmission coil. It can be controlled so that it can be transmitted. As an example, the timer 650 may transmit a specific event signal to the control unit 640 at a predetermined period during the ping transmission phase, and the control unit 640 controls the multiplexer 621 whenever the corresponding event signal is detected. It can be controlled so that a digital ping is transmitted through the corresponding transmitting coil.

In addition, the control unit 640 receives a predetermined transmission coil identifier from the demodulator 632 to identify through which transmission coil the response signal (e.g., signal strength signal) was received during the first detection signal transmission procedure. You may. At this time, the control unit 640 may receive a signal strength indicator corresponding to the transmission coil identifier from the demodulator 632. 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) for which the signal strength indicator was received during the first detection signal transmission procedure. You may. As another example, when there are a plurality of transmitting coils on which a signal strength indicator is received during the first detection signal transmission procedure, the control unit 640 transmits the second detection signal through the transmission coil on which the signal strength indicator with the largest value is received. In the procedure, the transmitting coil that will transmit the detection signal first is determined, and the multiplexer 621 can be controlled according to the decision result.

The communication unit 630 may be configured to include at least one of a modulation unit 631 and a demodulation unit 632.

The modulator 631 may modulate the control signal generated by the control unit 640 and transmit it to the multiplexer 621. Here, the modulation method for modulating the control signal is FSK (Frequency Shift Keying) modulation method, Manchester Coding modulation method, PSK (Phase Shift Keying) modulation method, Pulse Width Modulation method, differential 2 It may include, but is not limited to, a differential bi-phase modulation method.

When the demodulator 632 detects a signal received through the transmission coil, it can demodulate the detected signal and transmit it to the control unit 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 to this, and may include various status information to identify the status of the wireless power receiver.

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

Additionally, the demodulator 632 may demodulate the signal received through the transmission coil 623 and transmit it to the control unit 640. As an example, the demodulated signal may include a signal strength indicator, but is not limited to this, and the demodulated signal may include various status information of the wireless power receiver.

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

In addition, the wireless power transmitter 600 can not only transmit wireless power using the transmission coil unit 622, but also exchange various control signals and status information with the wireless power receiver through the transmission coil unit 622. . As another example, separate coils corresponding to the first to nth transmission coils of the transmission coil unit 622 may be additionally provided in the wireless power transmitter 600, and wireless power may be generated using the separate coils provided. 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 the frequency band used for wireless power signal transmission Short-distance two-way communication can be performed through different frequency bands. As an example, short-distance two-way communication may be any one of low-power Bluetooth communication, RFID communication, UWB communication, and ZigBee communication.

In addition, in the above description of FIG. 6, the power transmission unit 620 of the wireless power transmitter 600 includes a multiplexer 621 and a plurality of transmission coils 622, but this is only one embodiment and does not It should be noted that the power transmission unit 620 according to the embodiment may be composed of one transmission coil.

FIG. 7 is a block diagram for explaining the structure of a wireless power receiver linked with the wireless power transmitter according to 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, and a communication unit ( 760) and a main control unit 770. Here, the communication unit 760 may be configured to include a demodulation unit 761 and a modulation unit 762.

The wireless power receiver 700 shown in the example of FIG. 7 above is shown as being capable of exchanging 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 may provide short-distance two-way communication through a frequency band different from the 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 can convert AC power into DC power and transmit it to the DC/DC converter 730. The DC/DC converter 730 can convert the intensity of the rectifier output DC power into a specific intensity required by the load 740 and then transmit it to the load 740.

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

As an example, the main control unit 770 may determine whether an overvoltage has occurred by comparing the measured intensity of the rectifier output DC power with a predetermined reference value. As a result of the determination, if overvoltage has occurred, a packet notifying that overvoltage has occurred can 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 a detection signal has been received when the intensity of the rectifier output DC power is greater than a predetermined reference value, and when the detection signal is received, the signal intensity indicator corresponding to the detection signal is displayed in the modulator 762. ) can be controlled to be transmitted to the wireless power transmitter 600. As another example, the demodulator 761 demodulates the AC power signal between the receiving coil 710 and the rectifier 720 or the DC power signal output from the rectifier 720 to identify whether the detection signal is received and then controls the identification result. It can be provided to unit 770. At this time, the main control unit 770 can control the signal strength indicator corresponding to the detection signal to be transmitted through the modulation unit 761.

In particular, the main control unit 770 according to an embodiment of the present invention may determine whether the connected wireless power transmitter is a wireless power transmitter capable of fast charging based on information demodulated by the demodulation unit 760.

In addition, when a predetermined fast charging request signal requesting fast charging is received from the electronic device 30 of FIG. 1, the main control unit 770 generates a charging mode packet corresponding to the received fast charging request signal and modulates the modulator. It can be sent to (761). Here, a fast charging request signal from the electronic device may be received according to user menu selection on a certain 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 or wireless power based on the remaining battery level. You can also control the transmitter to stop fast charging and switch to a regular low-power charging mode.

The main controller 770 according to another embodiment may monitor the power consumption of an electric device in real time while charging in a general low-power charging mode. If the power consumption of the electronic device is greater than a predetermined standard value, the main controller 770 may generate a predetermined charging mode packet requesting switching to the fast charging mode and transmit it to the modulator 761.

The main control unit 770 according to another embodiment of the present invention may determine whether overheating has occurred by comparing the internal temperature value measured by the sensing unit 750 with a predetermined reference value. 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, rectifier output voltage intensity, CPU usage rate mounted on the electronic device, and user menu selection. It is determined whether this is necessary, and if the charging mode needs to be changed as a result of the determination, a charging mode packet containing the charging mode value to be changed may be generated and transmitted to the wireless power transmitter.

Figure 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 number 810 of FIG. 8, the wireless power transmitting end 10 and the wireless power receiving end 20 may encode or decode a transmission target packet based on an internal clock signal having the same period.

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

Referring to FIG. 1, when the wireless power transmitting end 10 or the wireless power receiving end 20 does not transmit a specific packet, the wireless power signal is modulated with a specific frequency, as shown at number 41 in FIG. 1. It may be an unused AC signal. On the other hand, when the wireless power transmitting end 10 or the wireless power receiving end 20 transmits a specific packet, the wireless power signal may be an alternating current signal modulated by a specific modulation method, as shown in drawing number 42 in FIG. 1. For example, the modulation method may include, but is not limited to, an amplitude modulation method, a frequency modulation method, a frequency and amplitude modulation method, and a phase modulation method.

Differential bi-phase encoding may be applied to the binary data of the packet generated by the wireless power transmitting end 10 or the wireless power receiving end 20, as shown in figure 820. In detail, differential two-level encoding requires two state transitions to encode data bit 1 and one state transition to encode data bit 0. That is, data bit 1 is encoded so that transition between HI and LO states 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 so that transitions between states and LO states occur.

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

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

Referring to FIG. 9, the packet format 900 used for information exchange between the wireless power transmitting end 10 and the wireless power receiving end 20 is used to obtain synchronization for demodulating the packet and to identify the correct start bit of the packet. A preamble field (910) for the packet, a header field (920) for identifying the type of message included in the packet, and a message for transmitting the contents (or payload) of the packet. It may be configured to include a 930) field and a checksum (940) field to identify whether an error occurred in the corresponding packet.

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

Additionally, the header 920 may be defined at each stage of the wireless power transfer procedure, and some header 920 values may be defined as the same value at different stages. As an example, referring to FIG. 9, it should be noted that the header value corresponding to the end power transfer of the ping stage and the end of power transfer of the power transfer stage may be the same as 0x02.

The message 930 includes data to be transmitted by the transmitting end of the packet. As an example, data included in the message 930 field may be a report, request, or 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 transmitting end identification information for identifying the transmitting end that transmitted the packet and receiving end identification information for identifying the receiving end that will receive the packet. Here, the transmitting end identification information and the receiving end identification information may include, but are not limited to, IP address information, MAC address information, product identification information, etc., and any information that can distinguish the receiving end and the transmitting end in the wireless charging system is sufficient.

The packet 900 according to another embodiment of the present invention may further include predetermined group identification information to identify the corresponding receiving group when the packet is to be received by multiple devices.

FIG. 10 is a diagram illustrating 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 packet transmitted from the wireless power receiver to the wireless power transmitter is a Signal Strength packet for transmitting strength information of the detected ping signal and a power transmission type for requesting the transmitter to stop transmitting power. (End Power Transfer), a Power Control Hold-off packet to transmit information on the waiting time to adjust the actual power after receiving a control error packet for control control, and a configuration to transmit configuration information of the receiver. Packets, identification packets and extended identification packets for transmitting receiver identification information, general request packets for transmitting general request messages, special request packets for transmitting special request messages, and transmitting reference quality factor values for FO detection. FOD status packet, control error packet to control the transmitter's transmitted power, renegotiation packet to initiate renegotiation, 24-bit received power packet and 8-bit received power packet to transmit received power intensity information, and charging status information of the current load. It may include a charging 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.

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

The foreign matter detection device according to this embodiment may be implemented in a wireless power transmission device, but this is only one embodiment and may be implemented in a measuring device for authentication of a wireless power reception device.

Referring to FIG. 11, the foreign matter detection device 1100 includes a power supply unit 1101, a DC-DC converter (1110), an inverter (1120), a resonance circuit 1130, a measurement unit 1140, It may be configured to include a communication unit 1160, a sensing unit 1170, and a control unit 1180. The foreign matter detection device 1100 according to this embodiment may be included in a wireless power transmission device.

The resonance circuit 1130 may include a resonance capacitor 1131 and a transmission coil 1132, and the communication unit 1160 may include at least one of a demodulation unit 1161 and a modulation unit 1162.

The power supply unit 1101 may receive DC power through an external power terminal and transmit it to the DC-DC converter 1110.

The DC-DC converter 1110 may convert the strength of DC power input from the power supply unit 1101 into DC power of a specific strength under the control of the control unit 1180. As an example, the DC-DC converter 1110 may be configured as a variable voltage device capable of adjusting the intensity of voltage, but is not limited to this.

The inverter 1120 can convert the converted direct current power into alternating current power. The inverter 1120 can convert input direct current power into an alternating current power signal and output it by controlling a plurality of switches provided therein.

As an example, the inverter 1120 may be configured to include at least one of a half bridge circuit and a full bridge circuit.

When the inverter 1120 is configured to include both a half-bridge circuit and a full-bridge circuit, the control unit 1180 can dynamically determine and control whether to operate the half-bridge circuit or the full-bridge circuit of the inverter 1120. .

The wireless power transmission device according to an embodiment of the present invention adaptively controls the bridge mode of the inverter 1120 according to the intensity of power required by the wireless power reception device or the power class of the wireless power reception device. can do.

Here, the bridge mode includes a half-bridge mode that generates an AC power signal using a half-bridge circuit and a full-bridge mode that generates an AC signal using a full bridge circuit.

For example, when low power of 5 watts (W) or less is required from the wireless power receiving device or the power rating of the wireless power receiving device corresponds to a predetermined low power (LP: Low Power) level, the control unit 1180 operates in half-bridge mode. The inverter 1120 can be controlled to operate as . On the other hand, when a high power of 15 watts is required from the wireless power receiving device or the power level is mid-power (MP: Mid_Power) level, the control unit 1180 can control the inverter 1120 to operate in full bridge mode. there is.

As another example, the wireless power transmission device may adaptively determine a bridge mode according to the temperature detected by the sensing unit 1170 and control the inverter 1120 according to the determined bridge mode. For example, if the temperature of the wireless power transmission device exceeds a predetermined standard value while transmitting wireless power through the half-bridge mode, the controller 1180 may disable the half-bridge mode and control the full-bridge mode to be activated. That is, the wireless power transmission device increases the voltage through the full bridge circuit for power transmission of the same intensity and reduces the intensity of the current flowing in the resonance circuit 1130, so that the internal temperature of the wireless power transmission device is below a predetermined standard value. You can control it to maintain it. In general, the amount of heat generated by electronic components mounted on electronic devices may be more sensitive to the intensity of current than to the intensity of voltage applied to the electronic component.

Additionally, the inverter 1120 can not only convert direct current power into alternating current power, but also dynamically change the intensity of the alternating current power delivered to the resonance circuit 1130.

For example, the inverter 1120 may adjust the intensity of the output AC power by adjusting the frequency of the reference alternating current signal (Reference Alternating Current Signal) used to generate AC power under the control of the controller 1180. To this end, the inverter 1120 may be configured to include a frequency oscillator that generates a reference alternating current signal with a specific frequency, but this is only one embodiment, and another example is that the frequency oscillator is separate from the inverter 1120. It can be installed on one side of the foreign matter detection device 1100.

As another example, a fixed frequency may be applied to the wireless power transmission device. In this case, the foreign matter detection device 1100 may be configured to further include a gate driver (not shown) for controlling the switch provided in the inverter 1120. The gate driver may receive at least one pulse width modulation signal from the control unit 1180, and a switch provided in the inverter 1120 according to the received pulse width modulation signal - for example, a MOFET switch constituting the selected bridge circuit. It can be controlled, but is not limited to this. The controller 1180 may control the intensity of the output power of the inverter 1120 by controlling the duty cycle (i.e., duty rate) and phase of the pulse width modulation signal. The control unit 1180 can control the intensity of power transmitted through the resonance circuit 1130 by adaptively controlling the duty cycle and phase of the pulse width modulation signal based on the feedback signal received from the wireless power receiver. .

The measurement unit 1140 measures at least one of the voltage, current, and impedance at both ends of the resonance capacitor 1131 according to the control signal from the controller 1180 to calculate the quality factor value and the inductance value for the resonance circuit 1130. there is. Additionally, the measurement unit 1140 may measure the temperature inside the wireless power receiver or at a specific location.

When an object placed in the charging area is detected in the selection step (410 or 510), before entering the ping step (420 or 520), the measuring unit 1140 measures the voltage across the resonance capacitor 1131 while power transmission is stopped. By measuring , the quality factor value corresponding to the resonance circuit 1130 can be calculated. At this time, the measuring unit 1140 may further calculate the inductance value corresponding to the resonance circuit 1130.

At least one of the calculated quality factor value and the inductance value is transmitted to the control unit 1180, and the control unit 1180 can store the values received from the measurement unit 1140 in a predetermined recording area.

When an FOD status packet is received from the modulator 1162 in the negotiation phase, the control unit 1180 may determine a threshold value (or threshold range) for determining whether a foreign substance exists based on the information included in the FOD status packet. Here, the determined threshold may include at least one of an inductance threshold and a quality factor threshold. When the value determined to determine whether a foreign substance exists is a critical range, the critical range may include at least one of an inductance critical range and a quality factor critical range.

Here, the FOD status packet may include a reference quality factor value or/and a reference inductux value corresponding to the wireless power receiver. The control unit 1180 may determine a quality factor threshold value or an inductance threshold value for determining whether a foreign substance exists based on the received reference quality factor value or/and reference inductance value. As an example, a value corresponding to 90% of the reference quality factor value and the reference inductance value may be determined as the quality factor threshold value and the inductance threshold value, but this is not limited to this, and the ratio is defined in consultation with the design of a person skilled in the art. can be set.

As an example, the control unit 1180 may determine that a foreign substance exists when the previously stored quality factor value is less than the determined quality factor threshold or when the previously stored inductance value is less than the determined inductance threshold.

If it is determined that a foreign substance exists, the control unit 1180 may control an alarm means (not shown) to stop power transmission and output a warning alarm indicating that a foreign substance has been detected. For example, the notification means may include a beeper, an LED lamp, a vibrating element, a liquid crystal display, etc., but is not limited thereto.

The reference quality factor value included in the FOD status packet may be determined as the smallest value among quality factor values calculated for the corresponding wireless power receiver at a specific location of the charging bed of the wireless power transmitter designated for standard performance testing.

The inductance value included in the FOD status packet may be determined as the smallest value among the inductance values calculated corresponding to the wireless power receiver at a specific location of the charging bed of the wireless power transmitter designated for standard performance testing.

Additionally, if a foreign substance is detected in the negotiation stage, the control unit 1180 returns to the selection stage and can control the measurement unit 1140 to calculate the quality factor value and inductance value of the resonance circuit 1130 at a predetermined period. At this time, the control unit 1180 can compare the quality factor value and inductance value obtained in the state in which the foreign material is detected with the predetermined quality factor threshold value and inductance threshold value, respectively, to determine whether the previously detected foreign material has been removed from the charging area. there is. As a result of the determination, if the foreign matter is removed, the controller 1180 may enter the power transmission phase and control charging to resume for the corresponding wireless power receiving device.

The demodulator 1161 demodulates the in-band signal received from the wireless power receiver and transmits it to the control unit 1180.

For example, in the power transmission step 440 or 510, the demodulator 1161 may demodulate a feedback signal received at a certain period for power control and transmit it to the control unit 1180. Here, the feedback signal may be a Signal Strength Packet (SSP) and a Control Error Packet (CEP) defined in the WPC standard, but is not limited thereto, and is a packet received at regular intervals from the wireless power receiver. This is enough.

If a specific feedback signal is not normally received within the first predefined time period in the power transmission step 440 or 510, the control unit 1180 determines that the wireless power receiver has been removed from the charging area and stops power transmission, You may enter the selection step (410 or 510). Here, the first time period may be determined as a predetermined multiple of the transmission period of the corresponding feedback signal, but is not limited thereto.

As described above, when an object is detected in the selection stage, the foreign matter detection device 1100 according to the present invention measures the quality factor value of the resonance circuit before entering the ping stage, and FOD status packet received in the negotiation stage. The presence of foreign substances can be determined by comparing the quality factor threshold value determined based on and the measured quality factor value.

Additionally, the control unit 1180 may receive a signal strength packet containing information about the received power strength in the power transmission step 440 or 510.

The control unit 1180 compares the received power intensity with a predefined received power intensity threshold (or threshold range) corresponding to the intensity of the current transmitted power, and determines that information about the received power intensity received from the corresponding wireless power receiver is a normal value. You can determine whether it is recognized or not.

As a result of confirmation, if the information regarding the received power intensity is not normal, the control unit 1180 may correct the received power intensity by applying a predetermined offset value.

The controller 1180 may calculate the wireless power path loss based on the current transmitted power intensity and the corrected received power intensity. Subsequently, the control unit 1180 may determine whether a foreign substance is placed on the wireless power transmission path by comparing the calculated path loss with a predetermined path loss threshold.

Of course, if the information about the received power intensity is normal, the controller 1180 can calculate the wireless power path loss based on the current transmitted power intensity and the received power intensity without performing a separate correction procedure.

The control unit 1180 according to an embodiment of the present invention may selectively perform at least one of a foreign matter detection procedure based on a quality factor value and a foreign matter detection procedure based on path loss according to user settings.

As an example, the control unit 1180 compares the quality factor threshold value determined based on the FOD status packet received in the negotiation stage with the measured quality factor value to determine whether a foreign substance is present, and the intensity of the current transmitted power in the power transmission stage. And, the path loss can be calculated based on the received signal strength packet, and the presence or absence of a foreign substance can be determined based on the calculated path loss. For example, if the control unit 1180 determines that a foreign substance exists in both of the two foreign substance determination results, it may finally determine that a foreign substance exists. As another example, if it is confirmed that a foreign substance exists based on one of two foreign substance determination results, the control unit 1180 may finally determine that the foreign substance has been detected.

The control unit 1180 according to another embodiment of the present invention may dynamically perform a foreign matter detection procedure based on path loss according to the type of wireless power receiver identified in the identification and configuration steps 420 and 520. Here, the type of identified wireless power receiver may be determined based on application software/firmware/protocol version information, manufacturer information, model information, receiver class or category, etc. For example, if it is confirmed that the identified wireless power receiver is a specific manufacturer or/and a specific model, the control unit 1180 performs a foreign matter detection procedure based on path loss, and other wireless power receivers perform a foreign matter detection procedure based on the quality factor value. It may also be controlled so that a foreign matter detection procedure is performed.

Figure 12 is a diagram for explaining the message structure of the Foreign Object Detection Status Packet according to the present invention.

Referring to FIG. 12, the foreign matter detection status packet message 1200 may have a length of 2 bytes, including a 6-bit Reserved (1201) field, a 2-bit long Mode (1202) field, and 1 byte. It may be configured to include a length Reference Quality Factor Value (1203) field. Here, all bits of the reservation (1201) field are recorded as 0.

As shown in drawing number 1204, when the mode 1202 field is set to binary '00', the reference quality factor value field 1203 contains a reference quality factor value determined by measurement with the corresponding wireless power receiver turned off. This may mean that it was recorded.

The standard quality factor value is the first quality factor value measured at the central location where the transmitting coil (Primary Coil) and the receiving coil (Secondary Coil) are well aligned with no FO near the wireless power receiver placed in the charging area and the wireless The smallest of the second quality factor values measured while moving with a certain distance offset from the center without rotation of the power receiver - for example, it may be +/- 5 mm in the x and y axes, but is not limited thereto. can be decided. Here, the second quality factor values may include quality factor values measured at at least four different locations.

Figure 13 is a state transition diagram for explaining a method of detecting foreign matter in a foreign matter detection device according to an embodiment of the present invention.

Referring to FIG. 13, when the foreign matter detection device detects an object placed in the charging area in the selection step 1310 (S1301), the quality factor value of the resonance circuit is measured and stored while wireless power transmission is temporarily suspended. The ping stage 1320 can be entered (S1302).

In the ping step 1320, the foreign matter detection device may periodically transmit a predetermined power signal (for example, it may be a digital ping signal) to identify the wireless power receiver.

When a response signal - for example, a signal strength signal (or signal strength packet) - is received in the ping step 1320, the foreign matter detection device enters the identification and configuration step 1330 to receive an identification packet and a configuration packet. there is. The foreign matter detection device can authenticate the corresponding receiver based on the received identification packet and set predetermined configuration parameters for power transmission to the corresponding receiver (S1303).

When the identification and configuration of the wireless power receiver are successfully completed, the foreign matter detection device may enter the negotiation step 1340 and receive a foreign matter detection status packet containing a reference quality factor value. The foreign matter detection device determines a quality factor threshold for determining the presence of a foreign matter based on the information contained in the foreign matter detection status packet, and compares the determined quality factor threshold with the previously measured and stored quality factor value to determine whether the foreign matter is present. can be determined (S1304).

As a result of the determination, if a foreign substance exists, the foreign substance detection device may stop transmitting power and return to the selection step 1310. On the other hand, as a result of the determination, if there is no foreign matter, the foreign matter detection device may enter the power transmission step 1350 and initiate wireless charging to the identified wireless power receiver.

The foreign matter detection device may perform power control based on a predetermined first feedback signal (for example, it may be a control error packet) in the power transmission step 1350.

During power control, the foreign matter detection device may identify the current received power intensity from the corresponding wireless power receiver based on a second feedback signal (for example, a signal intensity packet) containing information about the received signal intensity. At this time, the foreign matter detection device may determine whether the information received from the wireless power receiver is normal information based on the intensity of the current transmitted power and the intensity of the current received power. As a result of the determination, if the received information is not normal, the foreign matter detection device can correct the intensity of the received power by applying a predetermined offset value. The foreign matter detection device may calculate path loss based on the intensity of the current transmitted power and the intensity of the current (or corrected) received power, and determine whether a foreign substance exists based on the calculated path loss (S1305).

If a foreign substance is detected as a result of the determination in step 1305, the foreign substance detection device may return to the selection step 1310. Additionally, when it is confirmed that the wireless power receiver has been abnormally removed from the charging area or when charging is completed, the foreign matter detection device may return to the selection step (1310).

Of course, if no foreign matter is detected as a result of the determination in step 1305, the foreign matter detection device may maintain the power transmission step 1350 as is.

Figure 14 is a state transition diagram for explaining a method of detecting foreign matter in a foreign matter detection device according to another embodiment of the present invention.

Referring to FIG. 14, when the foreign matter detection device detects an object placed in the charging area in the selection step 1410 (S1401), the quality factor value of the resonance circuit is measured while wireless power transmission is temporarily suspended, and a predetermined recording area is selected. After saving, you can enter the ping step (1420) (S1402).

In the ping step 1420, the foreign substance detection device may periodically transmit a predetermined power signal (for example, it may be a digital ping signal) to identify the wireless power receiver.

When a response signal - for example, a signal strength signal (or signal strength packet) - is received in the ping step 1420, the foreign matter detection device enters the identification and configuration step 1430 to receive an identification packet and configuration packet. there is.

The foreign matter detection device may identify the type of wireless power receiver placed in the charging area based on the received identification packet and confirm whether the identified type is a wireless power receiver to which a foreign matter detection procedure based on path loss should be applied (S1403). .

This embodiment will be described assuming that the identified type is a receiver that must perform a foreign matter detection procedure based on path loss. Of course, it should be noted that if the identified type is not subject to the path loss-based foreign material detection procedure, the foreign material detection device may perform the foreign material detection procedure based on the quality factor value in the negotiation phase.

When the identification and configuration of the wireless power receiver is successfully completed, the foreign matter detection device can enter the negotiation phase (1440). At this time, the foreign matter detection device may enter the power transmission step 1450 without performing the foreign matter detection procedure based on the quality factor value because the identified receiver is subject to the foreign matter detection procedure based on path loss (S1404).

Hereinafter, step 1405 shown in FIG. 14 will be described in detail.

The foreign matter detection device may dynamically control the intensity of transmitted power based on a control error packet for power control in the power transmission step 1450.

During power control, the foreign matter detection device may receive a signal strength packet containing information about the received signal strength at a predetermined period. The foreign matter detection device can determine whether there is an abnormality in the information received from the corresponding receiver by comparing the received signal strength to the current transmitted power strength.

For example, the foreign matter detection device can know the maximum and minimum received signal strength that can be received from the receiver corresponding to the current transmitted power strength - that is, the critical range of the received signal strength. In this case, if the received signal strength confirmed based on the signal strength packet is outside the threshold range of the received signal strength, the foreign matter detection device may determine that the received signal strength information received from the corresponding receiver is not normal.

As another example, the foreign matter detection device may determine the received signal intensity threshold based on the current transmitted power intensity. In this case, if the received signal strength confirmed based on the signal strength packet exceeds the received signal strength threshold, the foreign matter detection device may determine that the received signal strength information received from the corresponding receiver is not normal.

If it is determined that the information received from the receiver is not normal, the foreign matter detection device can correct it by applying a predetermined offset value to the received signal strength. Here, the offset value may be a fixed value or a value determined dynamically in proportion to the intensity or power grade of the power currently being transmitted. Here, the power class may be divided into Low Power Class, Mid Power Class, etc., but is not limited thereto, and the power class may be defined differently depending on the applied standard and the design of those skilled in the art.

As an example, the corrected received signal strength (ARP) may be calculated by subtracting an offset value from the received signal strength (RP), but is not limited to this.

The foreign matter detection device calculates path loss based on the strength of the current transmitted power and the corrected received signal strength, and compares the calculated path loss with a predetermined path loss threshold to determine whether foreign matter exists on the wireless power transmission path. can do. Here, the path loss threshold may be a preset fixed value or a value dynamically determined depending on the type of transmitter and receiver. For example, if the calculated path loss exceeds a predetermined path loss threshold, the foreign matter detection device may determine that a foreign matter exists on the wireless transmission path.

If a foreign substance is detected in step 1405, the foreign substance detection device may return to the selection step 1310. Additionally, when it is confirmed that the wireless power receiver has been abnormally removed from the charging area or when charging is completed, the foreign matter detection device may return to the selection step 1410.

Of course, if no foreign matter is detected in step 1405, the foreign matter detection device may maintain the power transmission step 1450 as is.

Figure 15 is a flowchart for explaining a method for detecting foreign substances according to an embodiment of the present invention.

Referring to FIG. 15, when the wireless power transmitter enters the power transmission stage, it can control the intensity (TP) of the transmitted power based on the first feedback packet (S1501). Here, the first feedback packet may be a control error packet defined in the WPC standard, but it should be noted that this is only one embodiment and may differ depending on the wireless power transmission standard applied to the wireless power transmitter.

The wireless power transmitter may calculate the strength (RP) of the received signal based on the second feedback packet (S1502). Here, the second feedback packet may be a signal strength packet defined in the WPC standard, but it should be noted that this is only one embodiment and may differ depending on the wireless power transmission standard applied to the wireless power transmitter.

The wireless power transmitter according to one embodiment may compare whether the calculated strength (RP) of the received signal exceeds a predetermined first threshold (S1503).

As another example, the wireless power transmitter may check whether the calculated strength (RP) of the received signal is outside a predetermined first threshold range. Here, the first threshold range may be determined by the maximum received signal strength value and the minimum received signal strength value determined based on the current transmit power strength (TP).

As a result of the comparison in step 1503, if the received signal strength (RP) exceeds the first threshold or is outside the first threshold range, the wireless power transmitter uses a predetermined offset value (Offset) to determine the received signal strength (RP) ) can be corrected (S1504). As an example, the corrected received signal strength (ARP) can be calculated by subtracting the Offset from RP.

The wireless power transmitter may calculate the path loss (PL) based on the current transmitted power strength (TP) and the received signal strength (RP) (or the corrected received signal strength (ARP)) (S1505).

The wireless power transmitter according to one embodiment may check whether the calculated path loss (PL) exceeds the second threshold (S1506). Here, the second threshold may be determined based on at least one of an operating frequency used for power transmission, a transmitting coil type, a receiving coil type, and the intensity of transmitting power.

As another example, the wireless power transmitter may check whether the calculated path loss (PL) is outside a second predetermined threshold range. Here, the second threshold range may be determined as the maximum path loss value and minimum path loss value determined in proportion to the intensity (TP) of the current transmission power.

If the calculated path loss exceeds the second threshold or is outside the second threshold range, the wireless power transmitter may determine that a foreign substance exists on the wireless power transmission path and may output a predetermined warning alarm (S1507 ). At this time, the wireless power transmitter may stop transmitting power and enter the selection phase.

On the other hand, if the calculated path loss is less than the second threshold or is within the second threshold range, the wireless power transmitter may determine that no foreign matter is placed on the wireless power transmission path (S1508).

The wireless power receiver may determine that power greater than the actual received power is received due to errors in internal circuit elements, installed software errors, sensor errors, etc. For example, if the wireless power transmitter transmits 7 Watts of power, assuming a transmission efficiency of 80% or less, the wireless power receiver must receive 5.6 Watts or less of power. Of course, if foreign matter exists on the wireless power transmission path, the actual transmission efficiency may be much lower than 80%. However, some wireless power receivers may report to the wireless power transmitter that more than 6 watts of power is being received due to the error described above.

In this case, for a wireless power receiver that reports the intensity of received power as 6 watts or more, the wireless power transmitter may correct the intensity of received power by applying a predetermined offset (for example, it may be 2 watts). At this time, if the offset is 2 watts, the intensity of the corrected received power may be determined to be 4 watts. Afterwards, the wireless power transmitter can calculate the path loss based on the strength of the corrected received power and determine whether a foreign substance exists. If compensation for the received signal strength is not made, the path loss may have a very small value, and accordingly, the wireless power transmitter may determine that there is no foreign material even though there is actual foreign material on the wireless power transmission path. You can.

As described above, the present invention has the advantage of providing a foreign matter detection method and a wireless power transmission device capable of adaptively correcting the threshold value (or threshold range) for foreign matter detection based on whether the received power intensity is normal or not. there is.

In addition, the present invention has the advantage of providing a foreign matter detection method and device capable of detecting foreign matter by correcting path loss when a receiver is identified in which the intensity of received power relative to the intensity of transmitted power is abnormal in a fixed-frequency wireless power transmitter. there is.

Figure 16 is a block diagram for explaining the configuration of a foreign matter detection device according to an embodiment of the present invention.

The foreign matter detection device 1600 according to this embodiment may be configured in the form of a measuring device for authentication of a wireless power transmission device or a wireless power reception device.

Referring to FIG. 16, the foreign matter detection device 1600 includes a demodulation unit 1610, an adjustment unit 1620, a resonance unit 1630, a determination unit 1640, a correction unit 1650, a detection unit 1660, and a control unit ( 1670). Here, some components of the foreign matter detection device 1600 may be integrated and implemented on at least one microprocessor, and other components may be configured in the form of circuit elements, sensors, integrated circuits, etc.

The control unit 1670 can control the overall operation and input/output of the foreign matter detection device 1600.

When a wireless signal transmitted by a wireless power receiver is received through an antenna, the demodulator 1610 may demodulate the wireless signal and transmit the demodulated packet to the control unit 1660. As an example, the demodulator 1610 provides a predetermined packet that is fed back for power control received in the power transmission step - for example, a control error packet - and a predetermined packet that feeds back information on the intensity of power received from the wireless power receiver. For example, if a signal strength packet is demodulated, it can be delivered to the control unit 1660.

The adjuster 1620 may dynamically adjust the intensity of power transmitted through the resonator 1630 based on a feedback packet requesting power control.

The resonance unit 1630 may be configured to include a resonance circuit for wirelessly transmitting an AC power signal with a specific frequency.

The determination unit 1640 may determine whether information received from the wireless power receiver - for example, information about the intensity of received power - is normal.

As an example, the determination unit 1640 determines a first threshold indicating the maximum received signal strength that can be received by the wireless power receiver in response to the strength of the current transmitted power, and when the received power strength exceeds the first threshold, It can be determined that the received power intensity is not normal.

As another example, the determination unit 1640 determines a first threshold range indicating a power level that can be received by the wireless power receiver based on the intensity of the current transmitted power and a predefined transmission efficiency, and the received power intensity is set to the first threshold. If it is out of range, it may be determined that the received power intensity is not normal.

If the determination result of the determination unit 1640 is not normal, the correction unit 1650 may correct the intensity of the received power using a predetermined offset value.

The detector 1660 may calculate the path loss based on the strength of the current transmitted power and the strength of the received signal (or the strength of the corrected received signal).

Additionally, the detector 1660 may determine whether a foreign substance exists by comparing the calculated path loss with a predetermined threshold value (or threshold range).

Detailed operations of the components of the foreign matter detection device 1600 will be replaced with the description of the drawings.

The method according to the above-described embodiment can be produced as a program to be executed on a computer and stored in a computer-readable recording medium. Examples of computer-readable recording media include ROM, RAM, CD-ROM, and magnetic tape. , floppy disks, optical data storage devices, etc. may be included.

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

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

Accordingly, the above detailed description should not be construed as restrictive 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 (18)

In a method of detecting foreign matter in a wireless power transmitter that transmits wireless power to a wireless power receiver,
Receiving information about received power intensity from the wireless power receiver;
determining whether the received power intensity is normal;
As a result of the determination, if the received power intensity is not normal, correcting the received power intensity;
calculating a path loss for transmitted power based on the corrected received power intensity; and
Detecting foreign substances based on the calculated path loss
Includes,
The step of correcting the received power intensity includes determining an offset value based on the intensity of the current transmitted power; and correcting the received power intensity by subtracting the offset value from the received power intensity. According to paragraph 1,
A method of detecting a foreign substance, wherein the information about the received power intensity is received in a packet that is periodically fed back in the power transmission step. According to paragraph 2,
The feedback packet is
Foreign matter detection method, which is a signal strength packet defined in the WPC standard. According to paragraph 2,
The step of determining whether the received power intensity is normal is
determining a first threshold indicating the maximum received signal strength that can be received by the wireless power receiver in response to the strength of the current transmitted power; and
If the received power intensity exceeds the first threshold, determining that the received power intensity is not normal.
A method for detecting foreign substances, including. According to paragraph 2,
The step of determining whether the received power intensity is normal is
determining a first threshold range indicating a power level that can be received by the wireless power receiver based on the intensity of current transmission power and a predefined transmission efficiency; and
If the received power intensity is outside the first threshold range, determining that the received power intensity is not normal.
A method for detecting foreign substances, including. delete According to paragraph 1,
The step of detecting the foreign matter is
determining a path loss threshold based on the intensity of the current transmit power;
If the calculated path loss exceeds the path loss threshold, determining that a foreign substance exists on the wireless power transmission path.
A method for detecting foreign substances, including. According to paragraph 2,
A foreign substance detection method further comprising receiving a feedback signal for power control in the power transmission step, wherein the intensity of the currently transmitted power is adjusted based on the feedback signal. According to paragraph 1,
measuring a quality factor value after detecting an object and before entering the ping phase;
Upon receiving a foreign matter detection status packet including a reference quality factor value in the negotiation step, determining a quality factor threshold value corresponding to a second wireless power receiver based on the reference quality factor value; and
Comparing the measured quality factor value and the determined quality factor value to detect foreign substances
Further comprising: a method for detecting foreign substances. In a wireless power transmitter that transmits wireless power to a wireless power receiver,
a demodulator that receives a first packet for power control and a second packet containing information on received power intensity from the wireless power receiver;
a determination unit that determines whether the received power intensity is normal;
As a result of the determination, if the received power intensity is not normal, a correction unit for correcting the received power intensity; and
A detection unit that detects foreign substances by calculating the path loss for transmitted power based on the corrected received power intensity.
Includes,
The correction unit determines an offset value based on the intensity of the current transmitted power, and corrects the received power intensity by subtracting the offset value from the received power intensity. According to clause 10,
The first packet and the second packet are received periodically, and the wireless power transmitter further includes an adjuster that adjusts the intensity of transmitted power based on the first packet. According to clause 10,
The first packet and the second packet are a control error packet and a signal strength packet, respectively, defined in the WPC standard. According to clause 11,
The above judgment department
A first threshold indicating the maximum received signal strength that can be received by the wireless power receiver is determined based on the strength of the current transmitted power adjusted by the controller, and when the received power strength exceeds the first threshold, , A wireless power transmitter that determines that the received power intensity is not normal. According to clause 11,
The above judgment department
The step of determining whether the received power intensity is normal is
Determine a first threshold range indicating a power level that can be received by the wireless power receiver based on the intensity of the current transmission power adjusted by the controller and a predefined transmission efficiency, and the received power intensity is the first threshold. A wireless power transmitter that, when out of range, determines that the received power intensity is not normal. delete According to clause 10,
The detection unit
A wireless power transmitter that determines a path loss threshold based on the intensity of the current transmission power, and determines that a foreign substance exists on the transmission path of the wireless power when the calculated path loss exceeds the path loss threshold. . According to clause 10,
a measuring unit that measures quality factor values after detecting an object and before entering the ping stage;
Upon receiving a foreign matter detection status packet including a reference quality factor value in the negotiation stage, a quality factor threshold value corresponding to a second wireless power receiver is determined based on the reference quality factor value, and the measured quality factor value and the Control unit that detects foreign substances by comparing determined quality factor values
Further comprising a wireless power transmitter. A computer-readable recording medium on which a program for executing any one of the methods described in claims 1 to 5 and 7 to 9 is recorded.

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