WO2020085631A1 - Wireless power transmission method and apparatus - Google Patents

Abstract

The present invention relates to a wireless power transmission method and an apparatus therefor. A wireless power transmission method of a wireless power transmitter according to an embodiment may comprise the steps of: identifying a wireless power receiver; transmitting power to the identified wireless power receiver; determining whether a foreign object exists during the power transmission; on the basis of a transmission coil voltage, determining whether a transmission coil and a reception coil are aligned with each other; and determining whether to transmit power, on the basis of a result of the determination on whether the foreign object exists, and a result of the determination on whether the transmission coil and the reception coil are aligned with each other. Therefore, the present invention provides an advantage in that a foreign object can be more precisely detected during power transmission.

Description

Wireless power transmission method and apparatus

The present invention relates to a wireless power transmission technology, and more particularly, to a wireless power transmission method and apparatus capable of more accurately detecting a foreign material disposed in a charging area during power transmission.

With the recent rapid development of information and communication technology, a ubiquitous society based on information and communication technology has been formed.

In order to access information and communication devices anytime, anywhere, sensors in the computer chip with communication functions must be installed in all social facilities. Therefore, the problem of supplying power to these devices and sensors has become a new task.

In addition, as the types of portable devices such as tablet PCs and MP3 players as well as smartphones rapidly increase, charging a battery of a portable device requires time and effort by the user. As a method of solving such a problem, wireless power transmission technology has recently received attention.

Wireless power transmission technology (wireless power transmission or wireless energy transfer) is a technology that wirelessly transmits electric energy from a transmitter to a receiver using the induction principle of a magnetic field, and an electric motor or transformer using the electromagnetic induction principle was already used in the 1800s. Since then, a method of transmitting electrical energy by radiating electromagnetic waves such as radio waves, microwaves, and lasers has been attempted. The electric toothbrush, which is commonly used, and some wireless shavers are actually charged using the electromagnetic induction principle.

When a non-wireless power receiver conducts a non-wireless power receiver, that is, a foreign object (FO), an electromagnetic signal output through the antenna of the wireless power transmitter is induced to the foreign material, causing a temperature increase and charging efficiency. Can fall. For example, the foreign material may include coins, clips, pins, ballpoint pens, and the like.

If a foreign object is present between the wireless power receiver and the wireless power transmitter, not only the wireless charging efficiency is notably reduced, but the current absorbed by the foreign material increases the ambient temperature, and the temperature of the wireless power receiver and the wireless power transmitter also increases. You can. If the foreign matter located in the charging area is not removed, not only waste of power but also overheating may cause damage to the wireless power transmitter and the wireless power receiver.

Conventionally, a method for detecting a foreign substance based on power loss has been disclosed as a method for detecting a foreign substance in a wireless power transmitter during charging.

The method for detecting a foreign object based on power loss is a method of estimating power loss based on a difference value between a transmission power at a transmitter and a power actually received at a receiver, and determining whether a foreign object is present based on the estimated power loss. If a foreign material is disposed in the charging area, power loss due to the foreign material may be generated and power received by the actual receiver may be reduced.

The conventional wireless power transmitter simply determines the presence of foreign matter by comparing the estimated power loss with a reference value.

However, the power loss between the transmitter and the receiver may be changed according to the alignment state of the transmitting coil and the receiving coil as well as the reason due to the foreign matter disposed in the charging area.

The conventional method for detecting a foreign object based on power loss has a problem in that it is not possible to clearly distinguish whether the power loss is due to a foreign material or an alignment state of the transmitting and receiving coils.

Therefore, the conventional method for detecting foreign substances based on power loss has a disadvantage that it is difficult to accurately detect foreign substances during charging.

The present invention has been devised to solve the problems of the prior art described above, and an object of the present invention is to provide a wireless power transmission method and an apparatus therefor.

Another object of the present invention is to provide a wireless power transmission method and apparatus capable of more accurately detecting foreign matter by adaptively calculating power loss according to an alignment state of a transmitting and receiving coil.

Another object of the present invention is to provide a wireless power transmitter capable of accurately determining the cause of power loss during charging and minimizing unnecessary power waste and user inconvenience.

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

The present invention can provide a wireless power transmission method and devices therefor.

The wireless power transmission method of the wireless power transmitter according to the embodiment includes the steps of identifying a wireless power receiver, transmitting power to the identified wireless power receiver, determining whether a foreign object is present in the power transmission, and transmitting coil voltage. Determining whether to align the transmitting coil and the receiving coil based on the result of determining whether the foreign substance is present, and determining whether to transmit power based on the determination result of whether the transmitting coil and the receiving coil are aligned. It can contain.

Here, the step of determining the presence of a foreign material during the power transmission includes calculating a power loss and comparing the calculated power loss with a power loss threshold and determining whether a foreign material is present based on the comparison result. It may include.

In addition, if it is determined that a foreign object exists, the power transmission may be stopped and the selection step may be entered, and if it is determined that the foreign material does not exist, the power transmission may be maintained.

In addition, the wireless power transmission method of the wireless power transmitter further includes measuring the transmission coil voltage, and the power loss can be calculated based on at least the transmission coil voltage.

In addition, the wireless power transmission room of the wireless power transmitter further includes comparing the transmission coil voltage and the coil voltage threshold, and when the transmission coil voltage exceeds the coil voltage threshold, the transmission coil and the reception coil are aligned. If it is determined that the transmission coil voltage is less than or equal to the coil voltage threshold, it may be determined that the transmission coil and the reception coil are aligned.

A wireless power transmission method of a wireless power transmitter according to another embodiment includes the steps of identifying a wireless power receiver, transmitting power to the identified wireless power receiver, and measuring a first power loss and a transmission coil voltage during the power transmission. And calculating a corrected second power loss based on the first power loss and the transmission coil voltage.

In addition, the wireless power transmission method of the wireless power transmitter may further include determining whether to transmit power based on the second power loss.

In addition, when the second power loss exceeds the power loss threshold, it is determined that a foreign material exists, and then the power transmission is stopped, and then the selection step is entered. If the second power loss is less than or equal to the power loss threshold, the foreign material It is determined that this does not exist, and the power transmission can be maintained.

Further, the first power loss may be calculated as a difference between the transmission power of the wireless power transmitter and the received power of the wireless power receiver without considering the transmission coil voltage.

A wireless power transmission method of a wireless power transmitter according to another embodiment of the present invention includes the steps of identifying a wireless power receiver, transmitting power to the identified wireless power receiver, and measuring a first power loss during the power transmission. And measuring a transmission coil voltage when the first power loss exceeds a reference power, and calculating a second power loss by correcting the first power loss when the transmission coil voltage exceeds a reference voltage. It may include the step of determining the presence of foreign matter based on the power loss.

Here, the first power loss is calculated as a difference between the transmission power of the wireless power transmitter and the received power of the wireless power receiver without considering the transmission coil voltage, and the second power loss is based at least on the transmission coil voltage. It may be a correction value for the calculated first power loss.

In addition, when the second power loss exceeds the power loss threshold, it is determined that a foreign material exists, and then the power transmission is stopped, and then the selection step is entered. If the second power loss is less than or equal to the power loss threshold, the foreign material It is determined that this does not exist, and the power transmission can be maintained.

The wireless power transmission method of the wireless power transmitter according to another embodiment includes the steps of identifying a wireless power receiver, transmitting power to the identified wireless power receiver, and measuring a transmission coil voltage during the power transmission and the measurement. And determining whether to correct power loss based on the transmitted coil voltage.

Here, when the transmission coil voltage exceeds the coil voltage threshold, it is determined that the transmission coil and the reception coil are not aligned, and it is determined that correction of the power loss is necessary, and the transmission coil voltage is smaller than the coil voltage threshold. If it is equal to or equal to, it may be determined that the transmitting coil and the receiving coil are aligned, and it may be determined that correction of the power loss is not necessary.

In addition, if the corrected power loss according to the determination that the correction is necessary exceeds the power loss threshold, it is determined that a foreign substance exists, and then the power transmission is stopped and the selection step is entered, and the corrected power loss is the power. If it is below the loss threshold, it is determined that the foreign material does not exist and the power transmission can be maintained.

The effects on the method, apparatus and system according to the present invention are as follows.

The embodiment has an advantage of providing a method for detecting a foreign object in a wireless power transmitter and an apparatus therefor.

The embodiment has an advantage of providing a method and apparatus for detecting a foreign object in a wireless power transmitter capable of more accurately detecting a foreign object by adaptively calculating power loss according to an alignment state of the transmitting and receiving coils.

The embodiment has an advantage of providing a wireless power transmitter capable of accurately determining the cause of power loss during charging and minimizing unnecessary power waste and user inconvenience.

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

1 is a block diagram illustrating a wireless charging system according to an embodiment.

2 is a block diagram illustrating a wireless charging system according to another embodiment.

3 is a view for explaining a detection signal transmission procedure in a wireless charging system according to an embodiment.

4 is a state transition diagram for describing a wireless power transmission procedure according to an embodiment.

5 is a flowchart illustrating a foreign matter detection procedure in a wireless power transmission system according to an embodiment.

6 is a block diagram illustrating the structure of a wireless power transmission apparatus according to an embodiment.

7 is a view for explaining the antenna configuration of FIG. 6 according to an embodiment.

8 is a block diagram illustrating a structure of a wireless power receiving device interworking with the wireless power transmitting device according to FIG. 6 according to an embodiment.

9 is a system configuration diagram illustrating a conventional method for detecting a foreign object based on power loss.

10 is a system configuration diagram illustrating a foreign matter detection method based on power loss according to an embodiment.

11 is a view for explaining various situations in which power loss increases during charging.

12 shows exemplary power loss calculation results according to the presence or absence of foreign substances and the alignment state of the transmitting and receiving coils.

13 is a flowchart illustrating a method of detecting a foreign material in a wireless power transmitter according to an embodiment.

14 is a view for explaining a method of detecting foreign substances in a wireless power transmitter according to another embodiment.

15 is a view for explaining a method of detecting a foreign object in a wireless power transmitter according to another embodiment.

The wireless power transmission method of the wireless power transmitter according to an embodiment of the present invention includes the steps of identifying a wireless power receiver, transmitting power to the identified wireless power receiver, and determining whether a foreign object is present in the power transmission. Determining whether or not the transmission coil and the reception coil are aligned based on the transmission coil voltage, and determining whether to transmit power based on the determination result of whether the foreign material is present and the alignment result of the transmission coil and the reception coil. It may include the steps.

Hereinafter, apparatus and various methods to which embodiments of the present invention are applied will be described in more detail with reference to the drawings. The suffixes "modules" and "parts" for the components used in the following description are given or mixed only considering the ease of writing the specification, and do not have meanings or roles distinguished from each other in themselves.

In addition, the suffixes “module” and “unit” for components used in the following description may be implemented by hardware components (for example, including circuit elements, microprocessors, memories, sensors, etc.), This is only one embodiment, and some functions or all of the components may be implemented in software.

In the description of the embodiment, in the case of being described as being formed in the "top (top) or bottom (bottom)" of each component, the top (top) or bottom (bottom) is the two components are in direct contact with each other or It includes all that is formed by placing one or more other components between the two components. In addition, when expressed as "up (up) or down (down)", it may include the meaning of the downward direction as well as the upward direction based on one component.

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

The transmitter according to the present invention may be configured in a pad shape, a cradle shape, an AP (Access Point) shape, a small base station shape, a stand shape, a ceiling buried shape, a wall-mounted shape, etc., and one transmitter is provided with a plurality of wireless power receiving devices. You can also transmit power. To this end, the transmitter may include at least one wireless power transmission means.

Here, as the wireless power transmission means, various radio power transmission standards based on an electromagnetic induction method that generates a magnetic field in the coil of the power transmitting end and charges it using the electromagnetic induction principle in which electricity is induced in the coil of the receiving end under the influence of the magnetic field may be used. As an example, the wireless power transmission standard may include, but is not limited to, a standard technology of an electromagnetic induction method defined by Wireless Power Consortium (WPC) Qi and Power Matters Alliance (PMA), which are wireless charging technology standards bodies.

In addition, the receiver according to an embodiment of the present invention may be provided with at least one wireless power receiving means, and may also receive wireless power from one or more transmitters.

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

1 is a block diagram illustrating a wireless charging system according to an embodiment.

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

For example, the wireless power transmitting end 10 and the wireless power receiving end 20 may perform in-band communication for exchanging information using the same frequency band as the operating frequency used for wireless power transmission.

In the in-band communication, when the power signal 41 transmitted by the wireless power transmitting end 10 is received by the wireless power receiving end 20, the wireless power receiving end 20 modulates the received power signal and modulates the signal. 42 may be transmitted to the wireless power transmitter 10.

As another example, the wireless power transmitting end 10 and the wireless power receiving end 20 perform out-of-band communication for exchanging information using separate frequency bands different from the operating frequency used for wireless power transmission. You can also do

For example, information exchanged between the wireless power transmission end 10 and the wireless power reception end 20 may include control information as well as status information of each other. Here, the state information and control information exchanged between the transmitting and receiving terminals will become clearer through the description of the embodiments to be described later.

The in-band communication and the 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.

For example, the unidirectional communication may be that the wireless power receiving end 20 transmits information only to the wireless power transmitting end 10, but is not limited thereto, and the wireless power transmitting end 10 is only the wireless power receiving end 20. It may be sending information.

In the half-duplex communication method, two-way communication between the wireless power receiving end 20 and the wireless power transmitting end 10 is possible, but there is a feature that only one device can transmit information at any one time.

The wireless power receiver 20 according to an embodiment may acquire various status information of the electronic device 30.

For example, the status information of the electronic device 30 may include current power usage information, information for identifying a running application, CPU usage information, battery charge status information, battery output voltage / current information, etc., but is not limited thereto. If not, it is sufficient if the information can be obtained from the electronic device 30 and can be used for wireless power control.

 The wireless power transmitter 10 according to an embodiment may transmit a predetermined packet indicating whether to support fast charging to the wireless power receiver 20. The wireless power receiving end 20 may notify the electronic device 30 when it is determined that the connected wireless power transmitting end 10 supports the fast charging mode. The electronic device 30 may indicate that fast charging is possible through predetermined display means provided, for example, a liquid crystal display.

2 is a block diagram illustrating a wireless charging system according to another embodiment.

For example, as illustrated in reference numeral 200a, the wireless power receiving end 20 may be composed of a plurality of wireless power receiving devices, and a plurality of wireless power receiving devices connected to one wireless power transmitting end 10 may be wirelessly connected. Charging can also be performed.

At this time, the wireless power transmitter 10 may distribute and transmit power to a plurality of wireless power receivers in a time-division manner, but is not limited thereto. As another example, the wireless power transmitter 10 may distribute and transmit power to a plurality of wireless power receivers using different frequency bands allocated for each wireless power receiver.

At this time, the number of wireless power receiving devices that can be connected to one wireless power transmitting terminal 10 is based on at least one of a required power amount for each wireless power receiving device, a battery charging state, power consumption of an electronic device, and available power of a wireless power transmitting device. Can be adaptively determined.

As another example, as illustrated at 200b, the wireless power transmitter 10 may be configured with a plurality of wireless power transmitters.

In this case, the wireless power receiver 20 may be connected to a plurality of wireless power transmitters at the same time, and may also perform charging by receiving power simultaneously from the connected wireless power transmitters.

At this time, the number of wireless power transmitting devices connected to the wireless power receiving end 20 is adaptively based on the required power amount of the wireless power receiving end 20, the battery charging state, the power consumption of the electronic device, and the available power amount of the wireless power transmitting device. Can be determined.

3 is a view for explaining a detection signal transmission procedure in a wireless charging system according to an embodiment.

For example, the wireless power transmitter may be equipped with three transmission coils 111, 112, and 113. Each transmitting coil may have some areas overlapping with other transmitting coils, and the wireless power transmitter may use predetermined sensing signals 117 and 127 to detect the presence of the wireless power receiver through each transmitting coil. The digital ping signal-is sequentially transmitted in a predefined order.

As shown in FIG. 3, the wireless power transmitter sequentially transmits the detection signals 117 through the primary detection signal transmission procedure shown in FIG. 110, and a signal strength indicator (Signal) from the wireless power receiver 115. Strength Indicator, 116 may identify the received transmission coil (111, 112).

Subsequently, the wireless power transmitter sequentially transmits the detection signals 127 through the secondary detection signal transmission procedure illustrated in FIG. 120, and transmits power among the transmission coils 111 and 112 in which the signal strength indicator 126 has been received. The efficiency (or charging efficiency) —that is, the alignment between the transmitting coil and the receiving coil—can identify a good transmitting coil, and control the power to be transmitted through the identified transmitting coil—that is, to achieve wireless charging. .

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 transmission coil is well-aligned with the reception coil of the wireless power receiver.

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 the reference numerals 110 and 120 of FIG. 3, the wireless power transmitter Selects the most aligned transmission coil based on the signal strength indicator 126 received in each of the first transmission coil 111 and the second transmission coil 112, and performs wireless charging using the selected transmission coil. .

4 is a state transition diagram for describing a wireless power transmission procedure according to an embodiment.

4, the power transmission from the transmitter to the receiver according to an embodiment of the present invention is largely a selection phase (Selection Phase, 410), a ping phase (Ping Phase, 420), identification and configuration phase (Identification and Configuration Phase) , 430), a negotiation phase (Negotiation Phase, 440), a calibration phase (Calibration Phase, 450), a power transfer phase (Power Transfer Phase, 460) phase, and a renegotiation phase (Renegotiation Phase, 470).

The selection step 410 transitions when a specific error or specific event is detected while starting or maintaining the power transmission, including the steps S402, S404, S408, S410, and S412, for example. You can.

Here, specific errors and specific events will be clarified through the following description.

In addition, in the selection step 410, the transmitter may monitor whether an object is present on the interface surface.

If the transmitter detects that an object is placed on the interface surface, it may transition to the ping step 420 (S403).

For example, in the selection step 410, the transmitter transmits a very short pulse analog ping signal, and an active area of the interface surface based on a current change of the transmitting coil (or primary coil) ( Active Area). Here, the active area may refer to an area in which a receiver is disposed to enable wireless charging.

As another example, in the selection step 410, the transmitter may detect whether an object is present in an active area of the interface surface using a provided sensor.

As an example, the sensor may include a hall sensor, a pressure sensor, a capacitive sensor, a current sensor, a voltage sensor, a light detection sensor, and the like, and detect an object disposed in the active area through at least one sensor. .

When an object is detected in the selection step 410, the wireless power transmitter corresponds to an equipped LC resonant circuit, for example, the LC resonant circuit may include a coil (inductor) and a resonant capacitor connected in series. The quality factor can be measured.

When an object is detected in the selection step 410, the transmitter according to an embodiment of the present invention may measure a quality factor value to determine whether a wireless power receiver is disposed with a foreign object in the charging area. Here, the quality factor value may be measured before entering the ping step 420. Also, the quality factor value may be measured in a state in which power transmission through the transmission coil is temporarily suspended.

As an example, the quality factor value may be measured for a predefined reference operating frequency.

As another example, the quality factor value may be measured by sampling in a certain frequency unit within an operating frequency band used for wireless power transmission.

The transmitter according to an embodiment of the present invention may check the frequency value corresponding to the quality factor value having the maximum value among the measured quality factor values in the operating frequency band, and store it in a memory. Hereinafter, for convenience of description, a frequency having a maximum quality factor value in an operating frequency band is referred to as a quality factor peak frequency or simply a peak frequency for convenience of description.

The distribution of quality perception values measured in correspondence with the operating frequency band and the peak frequency of the quality factor may be different depending on the type of the wireless power transmitter.

In particular, the transmitter used to authenticate the receiver for the same operating frequency-the quality factor value measured using a business card called the 'transmitter for authentication' and the LCR meter for convenience of description below is a quality factor value measured in a commercial transmitter And may be different.

When the signal strength packet is received in the ping step 420, the wireless power transmitter may enter the identification and configuration step 430 (S403).

When the identification and configuration procedures are normally completed, the wireless power transmitter may enter the negotiation step 440 (S405).

In addition, when the identification and configuration procedures are normally completed, the wireless power transmitter may enter the power transmission step 460 according to the type of the receiver (S406).

Upon entering the negotiation step 440, the wireless power transmitter may receive a foreign object detection status packet including a reference quality factor value from the wireless power receiver.

The wireless power transmitter may determine a quality factor threshold value based on the received reference quality factor value.

Thereafter, the wireless power transmitter may compare the measured quality factor value and the quality factor threshold value to determine whether a foreign material is present.

However, if a foreign substance detection method for detecting the presence of a foreign substance by simply comparing the predetermined quality factor threshold value determined based on the reference quality factor value and the measured quality factor value is applied to a commercial transmitter, the accuracy for foreign substance detection may be lowered. have.

Here, the reference quality factor value refers to a quality factor value at a reference operating frequency measured in a state where no foreign matter is placed in the charging area of the authentication transmitter.

Compare the reference quality factor value received in the negotiation step 440 and the quality factor value corresponding to the reference operating frequency measured before the ping step 420-hereafter, for convenience of explanation, the current quality factor value is called a business card-to compare foreign matter You can judge if it exists.

However, the transmitter for which the reference quality factor value has been measured-that is, the transmitter for authentication-and the transmitter for which the current quality factor value has been measured may be different from each other. Therefore, the determined quality factor threshold for determining the presence of foreign substances may not be accurate.

Accordingly, the transmitter according to an embodiment of the present invention may receive a reference quality factor value corresponding to a corresponding transmitter type from a wireless power receiver, and determine a quality factor threshold value based on the received reference quality factor value.

The transmit coil may have an inductance and / or a series resistance component in the corresponding transmit coil reduced according to a change in the surrounding environment, thereby changing (shifting) the resonance frequency in the corresponding transmit coil. That is, the peak frequency of the quality factor, which is the frequency at which the maximum quality factor value in the operating frequency band is measured, may be shifted.

As an example, since the wireless power receiver includes a magnetic shield (shielding material) having a high magnetic permeability, a high magnetic permeability may increase the inductance value measured in the transmitting coil. On the other hand, a foreign substance of the metal type may reduce the inductance value.

로 계산된다.In general, in the case of an LC resonant circuit, the resonant frequency (f_resonant) is

Is calculated as

If only the wireless power receiver is placed in the charging area of the transmitter, the L value is increased, so that the resonance frequency is reduced. That is, the resonance frequency is shifted (shifted) to the left on the frequency axis.

On the other hand, when a foreign material is placed in the charging area of the transmitter, the L value decreases, and thus the resonance frequency increases. That is, the resonance frequency is shifted (shifted) to the right on the frequency axis.

The transmitter according to another embodiment may determine the presence or absence of a foreign material disposed in the charging region based on the change in the peak frequency of the quality factor.

The transmitter acquires information on a preset quality factor peak frequency corresponding to a corresponding transmitter type from the receiver or hereinafter, a business card called 'reference quality factor peak frequency (pf_reference)' or 'reference peak frequency' for convenience of description. It can be held in a predetermined recording area.

When the transmitter detects that an object is placed in the charging area, it can measure the value of the quality factor value in the operating frequency band before entering the ping step 420, and identify the quality factor peak frequency based on the measurement result. Here, in order to distinguish the identified quality factor peak frequency from the reference quality factor peak frequency, it is referred to as 'measurement quality factor peak frequency (pf_measured)' or 'measurement peak frequency'.

In the negotiation step 430, the transmitter may determine whether a foreign substance is present based on the reference quality factor peak frequency and the measured quality factor peak frequency.

If information regarding the reference quality factor peak frequency is received from the receiver, it may be received through a predetermined packet in the identification and configuration step 430 or the negotiation step 440.

As an example, the transmitter identifies and configures step 430 may transmit information regarding its transmitter type to the receiver. The receiver may read the reference quality factor peak frequency stored in advance in the corresponding memory in response to the received transmitter type information, and transmit information on the read reference quality factor peak frequency to the transmitter.

According to another embodiment, the transmitter may determine whether a foreign object exists by using both a foreign material detection method based on a quality factor peak frequency and a foreign material detection method based on a quality factor value.

For example, when there is no significant difference as a result of comparing the reference quality factor value corresponding to the transmitter type and the measured quality factor value, for example, when the difference between the two values is 10% or less, the reference quality corresponding to the transmitter type The presence or absence of foreign matter may be determined by comparing the peak frequency of the factor with the peak frequency of the measured quality factor.

On the other hand, if the difference between the two quality factor values exceeds 10%, the transmitter can immediately determine that a foreign substance is present.

According to another embodiment, when it is determined that there is no foreign material as a result of comparing the quality factor threshold value determined based on the reference quality factor value corresponding to the transmitter type and the measured quality factor value, the transmitter determines the reference quality factor peak frequency corresponding to the transmitter type and The presence or absence of foreign matter may be determined by comparing the measured peak frequency of the quality factor.

If it is not easy to detect a foreign object based on the quality factor value, the transmitter may request information on the reference quality factor peak frequency corresponding to the corresponding transmitter type to the identified receiver. Thereafter, when the information on the reference quality factor peak frequency is received from the receiver, the transmitter may determine whether a foreign substance is present using the reference quality factor peak frequency and the measurement quality factor peak frequency. Through this, the transmitter can more accurately detect the foreign matter disposed in the charging area.

Upon detecting an object, the transmitter may enter a ping step 420 to wake up the receiver, and transmit a digital ping to identify whether the detected object is a wireless power receiver.

In the ping step 420, if the transmitter does not receive a response signal for the digital ping-for example, a signal strength packet-from the receiver, it may transition back to the selection step 410.

In addition, in the ping step 420, the transmitter may transition to the selection step 410 when it receives a signal indicating that power transmission is completed from the receiver, that is, a charging complete packet.

When the ping step 420 is complete, the transmitter can transition to the identification and configuration step 430 to identify the receiver and collect receiver configuration and status information.

The transmitter may transmit information regarding the transmitter type to the receiver in the identification and configuration step 430.

The receiver may request information on the transmitter type from the identification and configuration step 430 to the transmitter, and the transmitter may transmit information on the transmitter type to the receiver according to the request of the receiver.

In addition, in the identification and configuration step 430, the transmitter may receive an unexpected packet (unexpected packet), or receive a desired packet for a predefined time (time out), a packet transmission error (transmission error), or power If no transfer contract is established (no power transfer contract), the process may transition to the selection step 410.

The transmitter may check whether entry into the negotiation step 440 is necessary based on the value of the negotiation field of the configuration packet received in the identification and configuration step 430.

As a result of the confirmation, if negotiation is required, the transmitter may enter the negotiation step 440 to perform a predetermined FOD detection procedure.

On the other hand, as a result of the confirmation, if negotiation is not required, the transmitter may immediately enter the power transmission step 460.

When the wireless power transmitter according to an embodiment is identified as a receiver supporting only the first power transmission mode in the identification and configuration step 430, the wireless power transmitter does not perform the negotiation step 440, and immediately transmits the power. You can enter 460.

The wireless power transmitter may periodically perform a process for detecting a foreign object after entering the power transmission step 460. Here, the foreign substance detection procedure may be a foreign substance detection procedure based on a quality factor value, but is not limited thereto, and a foreign substance detection procedure based on power loss may be applied.

The foreign matter detection procedure based on the power loss is a method of determining whether a foreign substance exists by comparing a difference between the transmitted power of the wireless power transmitter and the received power of the wireless power receiver with a predetermined reference value. will be.

For example, in the negotiation step 440, the transmitter may receive a Foreign Object Detection (FOD) Status Packet (FOD) containing a reference quality factor value. Alternatively, a FOD Status Packet including a reference peak frequency value corresponding to the transmitter type may be received.

As another example, in the negotiation step 440, the transmitter may receive a status packet including a reference quality factor value and a reference peak frequency value corresponding to the transmitter type. In this case, the transmitter may determine a quality factor threshold value for detecting foreign substances based on the reference quality factor value corresponding to the transmitter type.

The transmitter may determine a quality factor peak frequency threshold for detecting foreign substances based on a reference quality factor peak frequency value corresponding to the transmitter type. The transmitter measures the determined quality factor threshold and / or the determined quality factor peak frequency threshold to the measured quality factor value-means the quality factor value measured prior to the ping step 420-and / or the measured quality factor peak frequency It is also possible to detect the foreign matter disposed in the filling area by comparing with the value.

The transmitter can control the power transmission according to the result of the foreign object detection. For example, when a foreign object is detected, the transmitter may transmit a negative acknowledgment packet to the receiver in response to the foreign object detection status packet. Accordingly, power transmission may be stopped, but is not limited thereto.

The transmitter compares the determined quality factor peak frequency threshold and the measured quality factor peak frequency value to detect a foreign substance disposed in the charging area. The transmitter can control the power transmission according to the result of the foreign object detection. For example, when a foreign object is detected, the transmitter may transmit a negative acknowledgment packet (NACK packet) to the receiver in response to the foreign object detection status packet (FOD Status Packet). Accordingly, power transmission may be stopped, but is not limited thereto.

When a foreign object is detected, the transmitter may receive an End of Charge Message from the receiver, and may enter the selection step 410 accordingly.

The transmitter according to the embodiment may enter the power transmission step 460 when a foreign object is detected in the negotiation step 440 (S415).

On the other hand, if no foreign matter is detected, the transmitter may complete the negotiation step 440 for the transmission power, and may enter the power transmission step 460 through the correction step 450 (S407 and S409).

In detail, if no foreign matter is detected, the transmitter determines the strength of the power received at the receiving end in the correction step 450, and measures the power loss at the receiving end and the transmitting end to determine the intensity of the power transmitted from the transmitting end. You can. That is, the transmitter may predict (or calculate) the power loss based on the difference in intensity between the transmit power at the transmitting end and the received power at the receiving end in the correction step 450.

In the power transmission step 460, the transmitter may receive an unsolicited packet (unexpected packet), a desired packet for a predefined time (time out), or a violation of a preset power transmission contract (power). transfer contract violation), when charging is completed, the selection step 410 may be entered (S410).

In addition, in the power transmission step 460, the transmitter may transition to the renegotiation step 470 when it is necessary to reconfigure the power transmission contract according to a change in the transmitter state (S411). At this time, if the renegotiation is normally completed, the transmitter may return to the power transmission step 460 (S413).

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

The wireless power transmitter according to the embodiment may operate in any one of the first power transmission mode and the second power transmission mode based on the guaranteed power required by the wireless power receiver.

The wireless power receiver connected to the wireless power transmitter may be a receiver supporting only the first power transmission mode or a receiver supporting both the first power transmission mode and the second power transmission mode.

Here, the guaranteed power that can be set corresponding to the second power transmission mode may be greater than the guaranteed power that can be set in the first power transmission mode.

5 is a flowchart illustrating a foreign matter detection procedure in a wireless power transmission system according to an embodiment.

In detail, FIG. 5 is a diagram for describing a foreign matter detection procedure in the second power transmission mode.

Referring to FIG. 5, when an object is detected in the selection step, the wireless power transmitter 510 may measure the quality factor value at a predetermined reference operating frequency before entering the ping step (S501). Here, the reference operating frequency may be a resonance frequency, but is not limited thereto. The wireless power transmitter 510 may store the measured quality factor value in the internal memory (S502).

The wireless power transmitter 510 may enter the ping step and perform the detection signal transmission procedure described in FIG. 3 above (S503).

When the wireless power transmitter 510 detects the wireless power receiver 520, the wireless power transmitter 510 may enter an identification and configuration step to receive identification packets and configuration packets (S504 and S505).

The wireless power transmitter 510 may enter a negotiation step and receive a foreign object detection status packet from the wireless power receiver 520 (S506). Here, the foreign matter detection status packet may include a reference quality factor value.

The wireless power receiver 510 may determine a threshold value for determining whether a foreign object exists based on the reference quality factor value included in the foreign matter detection status packet (S507).

For example, the threshold value may be determined as a value smaller than a reference quality factor value by a predetermined ratio.

The wireless power transmitter 510 may detect a foreign material by comparing the measured quality factor value with the determined threshold value (S508). Here, when the measured quality factor value is smaller than the threshold value, the wireless power transmitter 510 may determine that a foreign substance exists in the charging area.

The wireless power transmitter 510 may transmit an ACK response or a NACK response or a ND (No Decision) response to the wireless power receiver 520 according to the result of the foreign object detection (S509).

When the NACK response or the ND response is received from the wireless power transmitter 510, the wireless power receiver 520 receives an electronic device (or battery) through its output terminal until power transmission is completely stopped by the wireless power transmitter 510. / Load) can be controlled so that power over a certain intensity is not supplied.

Here, the power of a certain intensity or more may be 5W as a standard, but is not limited thereto, and it is not limited to the design of a person skilled in the art and an electronic device equipped with a wireless power receiver 510 and / or a battery / load connected to the wireless power receiver 510 It can therefore be defined differently.

 6 is a block diagram illustrating a detailed structure of a wireless power transmission apparatus according to an embodiment of the present invention.

Referring to FIG. 6, the wireless power transmitter 600 includes a controller 610, a power converter 620, an antenna 630, a demodulator 640, a current sensor 650, a memory 660, and a power input terminal ( 670).

Here, the power converter 620 may include an inverter (Invertor, 621) and a DC-DC converter (DC-DC Convertor, 623).

The first DC voltage V_in applied through the power input terminal 670 may be converted into a second DC voltage V_rail by the DC-DC converter 623 and then applied as a driving voltage of the inverter 621. .

The controller 610 may generate the first to Nth switch control signals SC_1 and SC_N to control the plurality of switches provided in the inverter 621 and supply them to the inverter 621.

The inverter 621 may switch the second DC voltage V_rail according to the first to Nth switch control signals to generate an AC power signal.

Here, the first to Nth switch control signals may be pulse width modulated signals.

The antenna 630 may convert a resonance circuit (not shown) provided with an AC power signal received from the inverter 621 into an electromagnetic field signal and output the signal wirelessly.

In an embodiment, the antenna 630 may include an LC resonant circuit composed of at least one inductor (L) and at least one capacitor (Cacitor, C), that is, an LC tank.

In one embodiment, the antenna 630 may be in the form of a single coil composed of one transmission coil, that is, one inductor, but this is only one embodiment, and the antenna 630 according to another embodiment will be described later. As shown in 7, it may be composed of a plurality of transmission coils, that is, a plurality of transmission coils.

The second DC power, which is the output of the DC-DC converter 623, is used in combination with an inverter input voltage or V_rail or an inverter operating voltage for convenience of description.

The N values of the first to Nth switch control signals SC_1 and SC_N are the number of switches provided in the inverter 621, for example, may be metal-oxide semiconductor field-effect-transistor (MOSFET) switches. Can be the same as

The power sensor 650 may measure the strength of the current and voltage flowing through the antenna 630 according to the control signal of the controller 610, and transmit the measurement result to the controller 610.

For example, the controller 610 may control to measure the power flowing through the antenna 630 by transmitting a predetermined control signal to the power sensor 650 before entering the ping step after object detection.

As another example, the controller 610 may control to measure the voltage applied to the transmission coil of the antenna 630 by transmitting a predetermined control signal to the power sensor 650 after entering the power transmission step 460.

The controller 610 may identify the alignment state of the transmitting and receiving coils based on the measured voltage of the transmitting coil after entering the power transmission step 460.

If the voltage of the transmitting coil exceeds a predetermined reference value, the controller 610 determines that the transmitting and receiving coils are not aligned, and if the voltage of the transmitting coil is equal to or less than the reference value, the transmitting and receiving coils may be determined to be in an aligned state.

When the transmitting and receiving coils are not aligned, the controller 610 may correct power loss based on the measured voltage of the transmitting coil, and compare the corrected power loss with a predetermined power loss threshold to determine whether a foreign object is present.

When the transmit / receive coils are aligned, the controller 610 may calculate power loss without additional power loss correction, and compare the calculated power loss with the power loss threshold to determine whether a foreign object exists.

As described above with reference to FIG. 6, the wireless power transmitter according to the embodiment has an advantage in that foreign substances can be more accurately detected by adaptively calculating power loss according to the alignment state of the transmitting and receiving coils.

7 is a view for explaining the antenna configuration of FIG. 6 according to an embodiment.

Referring to FIG. 7, the antenna 630 may include a coil selection circuit 710, a coil assembly 720, and a resonance capacitor 730.

The coil assembly 720 may include at least one transmitting coil, that is, first to Nth coils.

The coil selection circuit 710 may include a switching circuit configured to transmit the output current I_coil of the inverter 621 to any one or at least one of the transmission coils included in the coil assembly 720.

For example, the coil selection circuit 710 may include first to Nth switches whose one end is connected to the output terminal of the inverter 621 and the other end is connected to the coil corresponding to it.

The first to Nth coils included in the coil assembly 720 may have one end connected to a corresponding switch of the coil selection circuit 710, and the other end thereof connected to the resonant capacitor 730.

The demodulator 640 may demodulate the signal between the coil assembly 720 and the resonant capacitor 730, where the signal is an amplitude modulated signal, and transmit it to the controller 610.

FIG. 8 is a block diagram illustrating a structure of a wireless power receiving device interworking with the wireless power transmitting device of FIG. 6.

Referring to FIG. 8, the wireless power receiver 800 includes a receiving antenna 810, a rectifier 820, a DC / DC converter (830), a switch 840, a load 850, and a modulator ( 860) and a controller 870.

The wireless power receiver 800 shown in the example of FIG. 8 described above may exchange information with a wireless power transmitter through in-band communication.

The receiving antenna 810 may include an inductor and at least one capacitor.

The AC power transmitted by the wireless power transmitter 600 may be transmitted to the rectifier 820 through the receiving antenna 810.

The rectifier 820 may convert AC power received through the receiving antenna 810 into DC power and transmit it to the DC / DC converter 830.

The controller 870 may boot according to the voltage applied from the DC / DC converter 830 to attempt communication connection with the wireless power transmitter.

In order for the wireless power receiver 800 to be booted, power higher than a reference value must be received.

The DC / DC converter 830 may convert the intensity of the output DC power of the rectifier 820 into DC power at a specific intensity required by the load 850 according to the control signal of the controller 870.

The controller 870 measures the output DC power intensity of the rectifier 820 and controls the switch 840 based on the measurement result.

For example, if the output voltage of the rectifier 820 exceeds a predetermined threshold, the controller 870 may control the switch 840 to be turned off so that no overvoltage is transmitted to the load 850.

The controller 870 may perform power control based on the output DC power of the rectifier 820.

When the overvoltage is detected, the controller 870 may control the modulator 860 to transmit a predetermined packet indicating that the overvoltage is detected to the wireless power transmitter 600.

The modulator 860 may transmit the corresponding packet to the wireless power transmitter 600 by amplitude-modulating the AC power signal received through the receiving antenna 810 using a modulating switch. At this time, the controller 870 may generate a predetermined switch control signal for controlling the modulation switch.

At this time, the wireless power transmitter 600 may demodulate through a demodulator 670 equipped with a signal amplitude-modulated by the wireless power receiver 800.

When entering the negotiation step 440, the wireless power receiver 800 according to an embodiment of the present invention may generate a foreign object detection status packet including a reference quality factor value and transmit it to the wireless power transmitter 600.

The wireless power transmitter 600 may determine a predetermined threshold value for determining whether a foreign object exists based on the reference quality factor value included in the foreign matter detection status packet.

When the wireless power receiver 800 enters the power transmission step 460, the intensity of the received power may be measured, and information on the measured intensity of the received power may be transmitted to the wireless power transmitter 600 through a predetermined packet. Here, the information on the strength of the received power may include at least one of voltage, current, and power.

When the wireless power receiver 800 enters the power transmission step 460, the intensity of the received power may be measured at the rear end of the rectifier 820.

The wireless power transmitter 600 may calculate the received power based on information on the strength of the received power received from the wireless power receiver 800.

The wireless power transmitter 600 may calculate power loss based on transmit power and receive power.

In addition, the wireless power transmitter 600 may check the alignment state of the transmission / reception coils and correct the calculated power loss according to the confirmation result.

The wireless power transmitter 600 may determine whether a foreign object is present based on the calculated or corrected power loss.

9 is a system configuration diagram illustrating a conventional method for detecting a foreign object based on power loss.

Referring to FIG. 9, the wireless power transmitter may include a power source 911, a converter 912, a transmission power sensor 913, an inverter 914, a transmission antenna 915, and a transmission controller 916.

The wireless power receiver may include a receive antenna 921, a rectifier 922, a DC / DC converter 923, a receive power sensor 924, and a receive controller 925. The wireless power receiver may perform charging by transmitting the received power to the load 926.

The converter 912 may convert DC or AC power applied from the power source 911 into specific DC power.

At this time, the converted power may be used as a driving voltage for the operation of the inverter 914. Also, the converted power may be used as a driving voltage required to drive the transmission controller 916.

The transmission controller 916 may control the converter 912 to adjust the driving voltage applied to the inverter 914.

The transmission controller 916 may measure the voltage at the output terminal of the converter 912-hereinafter referred to as transmission voltage V _TX for convenience of description.

The transmission current sensor 913 measures the current at the output terminal of the converter 912, that is, the current applied to the inverter 914 (hereinafter referred to as transmission current I _TX for convenience of description), and measures the measurement result. It can be provided to the transmission controller 916.

The transmission controller 916 may calculate the intensity P _TX of the transmission power based on the transmission voltage V _TX and the transmission current I _TX .

The inverter 914 is provided with a plurality of switches to generate an AC power signal. Here, the AC power signal may be generated based on a driving voltage applied from the converter 912 and a plurality of switch control signals applied from the transmission controller 916.

For example, when the inverter 914 is a full-bridge inverter including four switches Q1 to Q4, the switch control signal includes the first to fourth switch control signals SC_1 to SC_4. can do.

As another example, when the inverter 914 is a half-bridge inverter including two switches Q1 to Q4, the switch control signal is the first to second switch control signals SC_1 to SC_2. It can contain.

The AC power signal generated by the inverter 914 may be transmitted through the transmit antenna 915.

The transmitting antenna 915 may include an LC resonance circuit in which the capacitor L1 and the inductor C1 are connected in series.

The AC power signal received through the reception antenna 921 of the wireless power receiver may be rectified to DC by the rectifier 922 and then transmitted to the DC / DC converter 923.

The DC / DC converter 923 may convert the rectified DC power signal into a specific power required by the load 926.

The reception controller 925 may measure the output voltage V _RX of the DC / DC converter 923.

The receiving current sensor 924 may measure the output current I _RX of the DC / DC converter 923 and provide the measurement result to the receiving controller 925.

For example, the reception controller 925 may transmit information about V _RX and I _RX to the wireless power transmitter. In this case, the wireless power transmitter may calculate the received power P _RX based on V _RX and I _RX .

For example other, the reception controller 925 may send the information about the received power PRX calculated on the basis of P _RX V I _RX and _RX, and calculating the wireless power transmitter.

The wireless power receiver according to the embodiment may receive information on received power through in-band communication, where information on received power includes at least one of V _RX , I _RX , and P _RX- may be transmitted to a wireless power transmitter, This is only one embodiment, and the wireless power receiver according to another embodiment may transmit information regarding received power to the wireless power transmitter through out-of-band communication.

The transmission controller 916 may calculate the power loss P _LOSS based on the calculated transmission power P _TX and the reception power P _RX .

The transmission controller 916 may compare P _LOSS with a predetermined power loss threshold P _THRESHOLD to determine whether a foreign object is present.

For example, if P _LOSS is greater than P _THRESHOLD , the transmission controller 916 determines that a foreign substance exists in the charging region, and if P _LOSS is less than or equal to P _THRESHOLD , the transmission controller 916 has a foreign substance in the charging region. It can be judged not to.

The transmission controller 916 may enter the selection step 410 when a foreign substance is present in the charging area, and the transmission controller 916 may maintain the power transmission step 460 when the foreign substance is not present in the charging area.

As described above, in the state in which the transmitting coil L1 provided in the transmitting antenna 915 and the receiving coil L2 provided in the receiving antenna 921 are aligned, the wireless power transmitter described in FIG. 9 above is based on the power loss. It was possible to judge the existence.

However, the conventional wireless power transmitter has a problem in that it is not possible to accurately identify whether power loss of P _THRESHOLD or higher is due to foreign matter or mis-alignment of the transmission / reception coil.

For example, if the transmitting and receiving coils are not aligned in the absence of foreign matter, the wireless power transmitter must maintain charging. However, the conventional wireless power transmitter misinterprets the misaligned state of the transmitting / receiving coil as having a foreign material, and thus has a problem of stopping charging.

In particular, the conventional method for detecting a foreign substance based on power loss has a problem of not distinguishing between situation 2 and situation 3 of FIG. 11, which will be described later, and thus has a disadvantage in that the accuracy of foreign substance detection is poor.

10 is a system configuration diagram illustrating a foreign matter detection method based on power loss according to an embodiment.

The wireless power transmitter according to the embodiment of FIG. 10 may include a power source 1011, a converter 1012, a transmission power sensor 1013, an inverter 1014, a transmission antenna 1015, and a transmission controller 1016.

The wireless power receiver may include a receive antenna 1021, a rectifier 1022, a DC / DC converter 1023, a receive power sensor 1024, and a receive controller 1025. The wireless power receiver may transmit the received power to the load 1026 to perform charging.

The converter 1012 may convert DC or AC power applied from the power supply 1011 into specific DC power.

At this time, the converted power may be used as a driving voltage for the operation of the inverter 1014. Also, the converted power may be used as a driving voltage required to drive the transmission controller 1016. Here, the driving voltage may be a DC voltage.

The transmission controller 1016 may control the converter 1012 to adjust a driving voltage applied to the inverter 1014.

The transmission controller 1016 may measure the voltage of the output terminal of the converter 1012-referred to as a transmission voltage V _TX for convenience of description below.

The transmission current sensor 1013 measures the current at the output terminal of the converter 1012, that is, the current applied to the inverter 914 (hereinafter referred to as transmission current ITX for convenience of description)-and transmits the measurement result It can be provided to the controller 1016.

The transmission controller 1016 may calculate the intensity P _TX of the transmission power based on the transmission voltage V _TX and the transmission current I _TX . For example, PTX may be calculated as a product of V _TX and I _TX .

The transmission controller 1016 may measure the voltage V _{TX_COIL} applied to the transmission coil L1 of the transmission antenna 1015.

The transmission controller 1016 may correct power loss based on V _{TX_COIL} and determine whether a foreign object is present based on the corrected power loss.

The specific procedure for the transmission controller 916 to correct the power loss based on V _{TX_COIL} and to determine whether there is a foreign object based on the corrected power loss will become clearer through the description below.

The inverter 1014 is provided with a plurality of switches to generate an AC power signal. Here, the AC power signal may be generated based on a driving voltage applied from the converter 1012 and a plurality of switch control signals applied from the transmission controller 1016.

For example, when the inverter 1014 is a full-bridge inverter including four switches Q1 to Q4, the switch control signal includes the first to fourth switch control signals SC_1 to SC_4. can do.

As another example, when the inverter 1014 is a half-bridge inverter including two switches Q1 to Q4, the switch control signal is the first to second switch control signals SC_1 to SC_2. It can contain.

The AC power signal generated by the inverter 1014 may be transmitted through the transmission antenna 1015.

The transmit antenna 1015 may include an LC resonance circuit in which the capacitor L1 and the inductor C1 are connected in series.

The AC power signal received through the receiving antenna 1021 may be converted into a DC power signal by the rectifier 1022 and then transmitted to the DC / DC converter 1023.

The DC / DC converter 1023 may convert the rectified DC power signal into a specific power required by the load 1026.

The reception controller 1025 may measure the output voltage VRX of the DC / DC converter 1023.

The receiving current sensor 1024 may measure the output current IRX of the DC / DC converter 1023 and provide the measurement result to the receiving controller 1025.

For example, the reception controller 1025 may transmit information about V _RX and I _RX to the wireless power transmitter. In this case, the wireless power transmitter may calculate the received power P _RX based on V _RX and I _RX . Information about V _RX and I _RX may be transmitted to the wireless power transmitter at a predetermined cycle during charging.

As another example, the reception controller 1025 may calculate the received power P _RX based on V _RX and I _RX after entering the power transmission step, and periodically transmit information on the calculated P _RX to the wireless power transmitter. .

The wireless power receiver according to the embodiment may receive information on received power through in-band communication, where information on received power includes at least one of V _RX , I _RX , and P _RX- may be transmitted to a wireless power transmitter, This is only one embodiment, and the wireless power receiver according to another embodiment may transmit information regarding received power to the wireless power transmitter through out-of-band communication.

The transmission controller 1016 may calculate the power loss P _LOSS based on the calculated transmission power P _TX and the reception power P _RX .

The transmission controller 1016 may compare P _LOSS with a predetermined power loss threshold P _THRESHOLD to determine whether a foreign object is present.

For example, if P _LOSS is greater than P _THRESHOLD , the transmission controller 1016 determines that a foreign substance exists in the charging region, and if P _LOSS is less than or equal to P _THRESHOLD , the transmission controller 1016 has a foreign substance in the charging region. It can be judged not to.

The transmission controller 1016 may enter the selection step 410 when a foreign substance is present in the charging area, and the transmission controller 1016 may maintain the power transmission step 460 when no foreign substance is present in the charging area.

In the wireless power transmitter described in FIG. 10, when the transmitting coil L1 provided in the transmitting antenna 1015 and the receiving coil L2 provided in the receiving antenna 1021 are aligned, the presence of the foreign matter by the foreign matter detection method based on the conventional power loss You can judge whether or not.

However, in the conventional wireless power transmitter, if the transmitting coil L1 and the receiving coil L2 are not aligned, the power loss threshold P _THRESHOLD or higher is a power loss caused by a foreign object or a power loss caused by the transmission / reception coil not being aligned. There was a problem that could not be done.

For example, if the transmitting and receiving coils are not aligned in the absence of foreign matter, the wireless power transmitter must maintain charging. However, the conventional wireless power transmitter misinterprets the misaligned state of the transmitting / receiving coil as having a foreign material, and thus has a problem of stopping charging.

In particular, the conventional method for detecting a foreign substance based on power loss has a problem in that it is difficult to distinguish between situation 2 and situation 3 of FIG. 11 to be described later, and thus there is a disadvantage in that the accuracy of foreign substance detection is deteriorated.

Therefore, in order to detect a foreign substance more accurately, a wireless power transmitter needs to be provided with a means for distinguishing whether a power loss exceeding the power loss threshold P _THRESHOLD is a power loss caused by a foreign material or a power loss caused by a misalignment of the transmitting and receiving coils. .

The transmission controller 1016 according to the embodiment may measure the voltage V _{TX_COIL} applied to the transmission coil L1 and calculate power loss based on the measured V _{TX_COIL} . The transmission controller 1016 may compare the calculated power loss with a preset power loss threshold to determine whether a foreign object is present. As a result of the determination, if a foreign object is present, the transmission controller 1016 enters the selection step 410, and if there is no foreign material, the power transmission step 460 may be maintained.

The transmission controller 1016 according to another embodiment calculates the first power loss P _{LOSS # 1} by subtracting the received power P _RX from the transmission power P _TX , and the first power loss P _{LOSS # 1} sets the power loss threshold P _THRESHOLD If it exceeds, the voltage V _{TX_COIL} applied to the transmitting coil L1 can be measured.

Transmission controller 1016 can calculate the V _{TX_COIL} is a second power loss power losses corrected on the basis of V _{TX_COIL} when it exceeds a predetermined threshold coil voltage V _THRESHOLD P _{LOSS # 2.} The transmission controller 1016 may compare the second power loss P _{LOSS # 2} and the power loss threshold P _THRESHOLD to determine whether a foreign material is present.

For example, if the second power loss P _{LOSS # 2} exceeds the power loss threshold P _THRESHOLD , the transmission controller 1016 determines that a foreign object exists and may enter the selection step 410. If the second power loss P _{LOSS # 2} is less than or equal to the power loss threshold P _THRESHOLD , the transmission controller 1016 determines that no foreign material exists and may maintain the power transmission step 460.

The transmission controller 1016 according to another embodiment may measure the voltage V _{TX_COIL} applied to the transmission coil L1.

The transmission controller 1016 may compare V _{TX_COIL} to a predetermined coil voltage threshold V _THRESHOLD and calculate a first power loss P _{LOSS # 1} or a second power loss P _{LOSS # 2} according to the comparison result.

Here, the first power loss P _{LOSS # 1} is calculated by subtracting the received power P _RX from the transmission power P _TX , and the second power loss P _{LOSS # 2} corrects the first power loss P _{LOSS # 1} using V _{TX_COIL} . It can be one power loss.

For example, the transmission controller 1016 V _{TX_COIL} the V is less than or equal to _THRESHOLD, if the first calculated power loss P _{LOSS # 1,} and, V _{TX_COIL} exceeds V _THRESHOLD, the second calculation the power loss P _{LOSS # 2} can do.

The transmission controller 1016 may compare the calculated first power loss P _{LOSS # 1} or the second power loss P _{LOSS # 2} with a predetermined power loss threshold P _THRESHOLD to determine whether a foreign material is present.

For example, when the first power loss P _{LOSS # 1} exceeds the power loss threshold P _THRESHOLD , the transmission controller 1016 may determine that foreign matter is present in a state in which the transmitting and receiving coils are not aligned.

If the first power loss P _{LOSS # 1} is less than or equal to the power loss threshold P _{THRESHOLD, the} transmission controller 1016 may determine that the transmission / reception coils are not aligned and no foreign matter is present.

When the second power loss P _{LOSS # 2} exceeds the power loss threshold P _THRESHOLD , the transmission controller 1016 may determine that foreign matter is present in a state in which the transmitting and receiving coils are aligned.

When the second power loss P _{LOSS # 2} is less than or equal to the power loss threshold P _{THRESHOLD, the} transmission controller 1016 may determine that there is no foreign matter in the state in which the transmitting and receiving coils are aligned.

The transmission controller 1016 may enter the selection step 410 when it is determined that a foreign object exists, and may maintain the power transmission step 460 when it is determined that the foreign material does not exist.

In addition, when a foreign substance is detected, the transmission controller 1016 may generate a predetermined warning message indicating that the foreign substance is present in the charging area, and may output the corresponding warning message through the provided output means. To this end, the wireless power transmitter according to the embodiment may be provided with output means such as a liquid crystal display, a vibration motor, an LED lamp, a beeper, and a speaker.

The transmission controller 1016 according to the embodiment may display the alignment state of the transmission / reception coils through the provided output means.

As described above with reference to FIG. 10, the wireless power transmitter according to the embodiment has an advantage of more accurately detecting foreign matters by adaptively calculating power loss according to the alignment state of the transmitting and receiving coils.

11 is a view for explaining various situations in which power loss increases during charging.

Reference numeral 1110 in FIG. 11 shows a state in which foreign substances are not disposed in a charging area in a state in which the transmitting and receiving coils are aligned-a business card referred to as 'situation 1' for convenience of description below.

Drawing number 1120 shows a state in which the foreign material is not disposed in the charging area in a state in which the transmitting and receiving coils are not aligned-a business card called 'Situation 2' for convenience of explanation below. Comparing situation 1 and situation 2, situation 2 not only increases power loss compared to situation 1, but also increases the voltage V _{TX_COIL} applied to the transmitting coil.

Drawing number 1130 shows a state in which the foreign material is disposed in the charging area in a state in which the transmitting and receiving coils are aligned—hereinafter referred to as “Situation 3” for convenience of explanation. When situation 1 and situation 3 are compared, situation 3 has increased power loss compared to situation 1, but the voltage V _{TX_COIL} applied to the transmitting coil is maintained within a predetermined tolerance.

Drawing number 1140 shows a state in which foreign substances are disposed in a charging area in a state in which the transmitting and receiving coils are not aligned-a business card called 'Situation 4' for convenience of description below. Comparing situation 1 and situation 4, situation 4 not only increases power loss compared to situation 1, but also increases the voltage V _{TX_COIL} applied to the transmitting coil.

The wireless power transmitter according to the embodiment may determine whether the transmission / reception coils are aligned based on V _{TX_COIL} . When the transmission / reception coils are not aligned, the wireless power transmitter may correct power loss and determine whether a foreign object is present based on the corrected power loss.

As described above with reference to FIG. 11, the wireless power transmitter according to the embodiment has an advantage in that foreign substances can be more accurately detected by adaptively calculating power loss according to the alignment state of the transmitting and receiving coils.

12 shows exemplary power loss calculation results according to the presence or absence of foreign substances and the alignment state of the transmitting and receiving coils.

Referring to Drawing No. 1210, the transmission / reception coils are aligned, and the power loss calculated in the condition where there is no foreign substance (situation 1) and the power calculated in the condition where the transmission / reception coil is not aligned and no foreign substance exists (situation 2) The loss can be equal to 2.14.

The wireless power transmitter according to the embodiment may correct the power loss if the transmission / reception coils are identified in an unaligned state such that the power loss calculated in response to situation 1 and the power loss calculated in response to situation 2 are the same.

Referring to Drawing No. 1220, the transmission / reception coils are aligned, and the power loss calculated under the condition (situation 3) in which foreign matter exists and the transmission / reception coils are not aligned, and the power loss calculated in the condition (situation 4) in which foreign matter exists are 2.5 can be the same.

The wireless power transmitter according to the embodiment may correct the power loss when the transmission / reception coils are identified in an unaligned state such that the power loss calculated in response to situation 3 and the power loss calculated in response to situation 4 are the same.

As shown in FIG. 12, it can be seen that the power loss calculated in response to situations 3 and 4 is greater than the power loss calculated in response to situations 1 and 2.

The power loss threshold P _THRESHOLD for determining the presence or absence of foreign matter according to an embodiment may be set to a specific value between power loss corresponding to situations 1 to 2 and power loss corresponding to situations 3 to 4. In the above-described embodiment of FIG. 12, the power loss threshold P _THRESHOLD may be determined to be 2.32, which is an intermediate value between 2.14 and 2.5, but is not limited thereto.

For example, the power loss P _LOSS is Equation 1:

<수식 1>

<Equation 1>

Can be corrected by

Where P _TX and P _RX is the measured transmit power and the received power, P _b is the power loss measured in advance when the transmit / receive coil is not more than 10mm aligned and no foreign matter is present, P _a is the transmit and receive coil is aligned, and no foreign matter is present Power loss measured in advance, V _TX-COIL is the voltage measured at the transmit coil, V _b is the transmit coil voltage measured when the transmit / receive coil is not aligned more than 10 mm and no foreign matter is present, and V _a is the transmit / receive voltage. This is the transmission coil voltage measured when the coil is aligned and no foreign substance is present.

In another example, power loss P _LOSS is Equation 2:

<수식 2>

<Equation 2>

It can also be corrected by.

Here, P _b is the power loss measured when the transmitting / receiving coil is not aligned more than 10 mm and no foreign matter is present, and P _a is the power loss measured when the transmitting / receiving coil is aligned and no foreign matter is present.

13 is a flowchart illustrating a method of detecting a foreign material in a wireless power transmitter according to an embodiment.

Referring to FIG. 13, the wireless power transmitter may enter the power transmission step 460 to measure the transmission coil voltage V _{TX_COIL} (S1310).

The wireless power transmitter measures the measured transmit coil voltage. Power loss P _LOSS may be calculated based on V _{TX_COIL} (S1320). Here, the power loss P _LOSS may be calculated by Equation 1 or Equation 2 described in FIG. 12 above.

The wireless power transmitter may compare the calculated power loss P _LOSS with the power loss threshold P _THRESHOLD (S1330).

If the power loss P _LOSS is greater than the power loss threshold P _{THRESHOLD, the} wireless power transmitter may determine that a foreign substance exists in the charging area and enter the selection step 410 (S1340 to S1350).

If the power loss P _LOSS is less than or equal to the power loss threshold P _{THRESHOLD, the} wireless power transmitter may determine that there is no foreign substance in the charging area and maintain the power transmission step 460 (S1360).

As described above with reference to FIG. 13, when the wireless power transmitter according to the embodiment enters the power transmission step 460, the power loss is considered in consideration of the voltage of the transmission coil, thereby more accurately detecting foreign matter. have.

14 is a view for explaining a method of detecting foreign substances in a wireless power transmitter according to another embodiment.

Referring to FIG. 14, the wireless power transmitter may enter the power transmission step 460 to calculate the first power loss P _{LOSS # 1} (S1410).

The wireless power transmitter may compare the calculated first power loss P _{LOSS # 1} with the power loss threshold P _THRESHOLD (S1420).

If the first power loss P _{LOSS # 1} is less than or equal to the power loss threshold P _{THRESHOLD, the} wireless power transmitter may determine that there is no foreign substance in the charging area and maintain the power transmission step 460 (S1430).

When the first power loss P _{LOSS # 1} is greater than the power loss threshold P _{THRESHOLD, the} wireless power transmitter may measure the transmission coil voltage V _{TX_COIL} (S1440).

The wireless power transmitter may compare the transmission coil voltage V _{TX_COIL} and the coil voltage threshold V _THRESHOLD (S1450).

If the transmission coil voltage V _{TX_COIL} is less than or equal to the coil voltage threshold V _{THRESHOLD, the} wireless power transmitter may determine that a foreign substance exists in the charging area and enter the selection step 410 (S1460).

On the other hand, the wireless power transmitter may calculate the second power loss P _{LOSS # 2} when the transmission coil voltage V _{TX_COIL} is greater than the coil voltage threshold V _THRESHOLD (S1470). Here, the second power loss P _{LOSS # 2} may be calculated by Equation 1 or Equation 2 described in FIG. 12 above.

The wireless power transmitter may compare the second power loss P _{LOSS # 2} with the power loss threshold P _THRESHOLD (S1480).

If the first power loss P _{LOSS # 1} is less than or equal to the power loss threshold P _{THRESHOLD, the} wireless power transmitter may determine that no foreign material exists and maintain the power transmission step 460 (S1490).

On the other hand, if the first power loss P _{LOSS # 1} is greater than the power loss threshold P _THRESHOLD , the wireless power transmitter may determine that a foreign material exists and enter the selection step 410 (S1495).

As described above with reference to FIG. 14, the wireless power transmitter according to the embodiment has an advantage in that foreign substances can be more accurately detected by adaptively calculating power loss according to the alignment state of the transmitting and receiving coils.

15 is a view for explaining a method of detecting a foreign object in a wireless power transmitter according to another embodiment.

The wireless power transmitter may enter the power transmission step 460 to measure the transmission coil voltage V _{TX_COIL} (S1510).

The wireless power transmitter may compare the transmission coil voltage V _{TX_COIL} and the coil voltage threshold V _THRESHOLD (S1520).

The wireless power transmitter has a transmit coil voltage V _{TX_COIL} If less than or equal to the coil voltage threshold V _THRESHOLD , The first power loss P _{LOSS # 1} may be calculated (S1530).

The wireless power transmitter may compare the calculated first power loss P _{LOSS # 1} with the power loss threshold P _THRESHOLD (S1540).

If the first power loss P _{LOSS # 1} is greater than the power loss threshold P _{THRESHOLD, the} wireless power transmitter may determine that the transmitting / receiving coil is not aligned, and that there is a foreign substance in the charging area, and may enter the selection step 410. (S1550).

If the first power loss P _{LOSS # 1} is less than or equal to the power loss threshold P _{THRESHOLD, the} wireless power transmitter determines that the transmitting / receiving coil is not aligned and there is no foreign matter in the charging area, and the power transmission step 460 is performed. It can be maintained (S1560).

As a result of comparison of 1520, the transmission coil voltage V _{TX_COIL} is If the coil voltage threshold is greater than V _THRESHOLD , The wireless power transmitter may calculate the second power loss P _{LOSS # 2} (S1570).

When the second power loss P _{LOSS # 2} is greater than the power loss threshold P _{THRESHOLD, the} wireless power transmitter may enter the selection step 410 by determining that the transmitting / receiving coil is in an aligned state and that foreign matter is present in the charging region ( S1590).

If the second power loss P _{LOSS # 2} is less than or equal to the power loss threshold P _{THRESHOLD, the} wireless power transmitter maintains the power transmission step 460 by determining that the transmitting / receiving coil is aligned and that there is no foreign substance in the charging area. It can be (S1595).

15, the wireless power transmitter according to the embodiment adaptively calculates the first power loss P _{LOSS # 1} or the second power loss P _{LOSS # 2} according to the alignment state of the transmitting and receiving coils, thereby more accurately It has the advantage of being able to detect foreign substances.

The present invention can be applied to a wireless power transmission device that transmits power wirelessly.

Claims (10)

Identifying a wireless power receiver; Transmitting power to the identified wireless power receiver; Determining whether a foreign object is present during the power transmission; Determining whether the transmitting coil and the receiving coil are aligned based on the transmitting coil voltage; And Determining whether to transmit power based on the determination result of whether the foreign substance is present and whether the transmission coil is aligned with the reception coil. Wireless power transmission method of a wireless power transmitter comprising a. According to claim 1, The step of determining the presence of foreign matter during the power transmission, Measuring a transmission coil voltage applied to the transmission coil; Calculating a power loss based on the measured transmit coil voltage; Comparing the calculated power loss with a power loss threshold; And Determining whether a foreign substance is present based on the comparison result Wireless power transmission method of a wireless power transmitter comprising a. According to claim 2, If it is determined that a foreign substance exists according to the comparison result, the power transmission is stopped and the selection step is entered, If it is determined that the foreign material does not exist according to the comparison result, the wireless power transmission method of the wireless power transmitter maintaining the power transmission. According to claim 2, And comparing the transmission coil voltage with a coil voltage threshold, If the transmitting coil voltage exceeds the coil voltage threshold, it is determined that the transmitting coil and the receiving coil are not aligned. If the transmitting coil voltage is less than or equal to the coil voltage threshold, the transmitting coil and the receiving coil are aligned. Wireless power transmission method of the wireless power transmitter is judged to be. Identifying a wireless power receiver; Transmitting power to the identified wireless power receiver; Measuring a first power loss and a transmission coil voltage during the power transmission; And Calculating a corrected second power loss based on the first power loss and the transmission coil voltage. Wireless power transmission method of a wireless power transmitter comprising a The method of claim 5, And determining whether to transmit power based on the second power loss. The method of claim 6, When the second power loss exceeds the power loss threshold, it is determined that a foreign object exists, and the power transmission is stopped, and then the selection step is entered, If the second power loss is less than or equal to the power loss threshold, the wireless power transmission method of the wireless power transmitter maintaining the power transmission by determining that the foreign material does not exist. The method of claim 5, The first power loss is a wireless power transmission method of the wireless power transmitter is calculated as the difference between the transmission power of the wireless power transmitter and the received power of the wireless power receiver without considering the transmission coil voltage. Identifying a wireless power receiver; Transmitting power to the identified wireless power receiver; Measuring a first power loss during the power transmission; Measuring a transmission coil voltage when the first power loss exceeds a reference power; Calculating a second power loss by correcting the first power loss when the transmission coil voltage exceeds a reference voltage; And Determining whether a foreign object is present based on the second power loss Wireless power transmission method of a wireless power transmitter comprising a. The method of claim 9, The first power loss is calculated as a difference between the transmission power of the wireless power transmitter and the reception power of the wireless power receiver without considering the transmission coil voltage, The second power loss is calculated based on at least the transmission coil voltage and is a correction value for the first power loss,  If the second power loss exceeds the power loss threshold, it is determined that a foreign material exists, and then the power transmission is stopped and the selection step is entered. If the second power loss is less than or equal to the power loss threshold, the foreign material is present. The wireless power transmission method of the wireless power transmitter to maintain the power transmission by determining not to.

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