WO2019225806A1

WO2019225806A1 - Wireless power transmission method and device

Info

Publication number: WO2019225806A1
Application number: PCT/KR2018/007892
Authority: WO
Inventors: 박유리; 권용일; 장성재
Original assignee: 엘지이노텍(주)
Priority date: 2018-05-23
Filing date: 2018-07-12
Publication date: 2019-11-28
Also published as: KR102572975B1; KR20210000334A

Abstract

The present invention relates to a wireless power transmission method and a device therefor. A wireless power transmission method according to an embodiment of the present invention can comprise the steps of: measuring a resonance quality factor and a resonant frequency; receiving a foreign object detection state packet comprising a reference resonance quality factor and a reference resonant frequency; calculating a resonant frequency bandwidth on the basis of the resonance quality factor and the resonant frequency; calculating a reference resonant frequency bandwidth on the basis of the reference resonance quality factor and the reference resonant frequency; and determining whether or not a foreign object exists on the basis of the resonant frequency bandwidth and the reference resonant frequency bandwidth.

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 therefor capable of detecting foreign matter during wireless charging.

When a conductor other than a wireless power receiver, that is, a foreign object (FO), exists in the wirelessly chargeable area, an electromagnetic signal transmitted from the wireless power transmitter may be induced in the FO to increase the temperature. For example, the FO may include a coin, a clip, a pin, a ballpoint pen, and the like.

If the FO is present between the wireless power receiver and the wireless power transmitter, not only the wireless charging efficiency is significantly lowered but also the temperature of the wireless power receiver and the wireless power transmitter may rise together due to an increase in the ambient temperature caused by the FO. If the FO located in the charging area is not removed, not only power waste but also overheating may cause damage to the wireless power transmitter and the wireless power receiver.

In addition, even if the FO does not exist in the actual charging region, charging may be stopped when the wireless power transmitter incorrectly determines that the foreign substance exists in the charging region.

Therefore, accurately detecting the FO located in the charging area is an important issue in the field of wireless charging technology.

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

Another object of the present invention is to provide a wireless power transmitter capable of detecting foreign matter more accurately.

It is still another object of the present invention to provide a wireless power transmission method and apparatus to prevent unnecessary charge interruption by minimizing foreign matter detection errors.

It is still another object of the present invention to provide a wireless power transmitter that prevents damage to a device caused by a foreign material and enables seamless charging through adaptive transmission power control according to the presence of a foreign material.

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

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

Wireless power transmission method according to an embodiment of the present invention comprises the steps of measuring the resonance quality factor and the resonance frequency; Receiving a foreign matter detection status packet comprising a reference resonance quality factor and a reference resonance frequency; Calculating a resonance frequency bandwidth based on the resonance quality factor and the resonance frequency; Calculating a reference resonance frequency bandwidth based on the reference resonance quality factor and the reference resonance frequency; And determining whether a foreign substance is present based on the resonance frequency bandwidth and the reference resonance frequency bandwidth.

Wireless power transmission method according to another embodiment of the present invention comprises the steps of measuring the resonance quality factor and the resonance frequency; Receiving a foreign matter detection status packet including a reference resonance frequency bandwidth; Calculating a resonance frequency bandwidth based on the resonance quality factor and the resonance frequency; And determining whether a foreign substance is present based on the resonance frequency bandwidth and the reference resonance frequency bandwidth.

Wireless power transmission method according to another embodiment of the present invention comprises the steps of measuring the resonance quality factor and the resonance frequency; Receiving a foreign matter detection status packet comprising a reference resonance quality factor, a reference resonance frequency and a reference resonance frequency bandwidth; Calculating a resonance frequency bandwidth based on the resonance quality factor and the resonance frequency; Determining a reference resonance frequency bandwidth based on at least one of the reference resonance quality factor, a reference resonance frequency, and a reference resonance frequency bandwidth; And determining the presence or absence of the foreign matter based on the resonance frequency bandwidth and the reference resonance frequency bandwidth.

In addition, the resonant frequency is a frequency at which the resonator amplification ratio is maximum, and the resonance quality factor may be calculated based on the resonator amplification ratio to the resonant frequency.

In addition, the resonance frequency is a frequency at which the peak-to-peak voltage of the resonator is maximum, and the resonance quality factor may be calculated based on the peak-to-peak voltage at the resonance frequency.

The determining of the presence or absence of the foreign matter based on the resonance frequency bandwidth and the reference resonance frequency bandwidth,

And comparing the variation ratio of the resonance frequency bandwidth with the threshold ratio to determine whether foreign matter is present.

The change ratio of the resonance frequency bandwidth may be calculated by dividing a value obtained by subtracting the reference resonance frequency bandwidth from the resonance frequency bandwidth by the reference resonance frequency bandwidth.

In addition, the threshold ratio may be set to any one of a value greater than 25% and less than 35%.

The determining of the presence or absence of the foreign matter by comparing the change ratio of the resonance frequency bandwidth with a threshold ratio may include determining that there is a foreign matter and determining a NACK response when the change ratio of the resonance frequency bandwidth exceeds the threshold ratio. Transmitting; And if the change ratio of the resonance frequency bandwidth is smaller than the threshold ratio, determining that no foreign matter exists and transmitting an ACK response.

Another embodiment of the present invention may provide a computer readable recording medium having recorded thereon a program for executing any one of the wireless power transfer control methods.

The above aspects of the present invention are only some of the preferred embodiments of the present invention, and various embodiments in which the technical features of the present invention are reflected will be described in detail below by those skilled in the art. Can be derived and understood.

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

The present invention has the advantage of providing a wireless power transmission method and apparatus for wireless charging.

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

In addition, the present invention has the advantage of providing a wireless power transmission method and apparatus to prevent unnecessary charging interruption by minimizing foreign matter detection error.

In addition, the present invention has the advantage of providing a wireless power transmitter to prevent damage to the device by foreign matter, and to enable seamless charging through adaptive transmission power control according to the presence of foreign matter.

In addition, the present invention has the advantage that can provide a wireless power transmitter capable of transmitting a wide range of wireless power stably in accordance with the type and power transmission environment of the receiver.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned above may 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 of the present invention.

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

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

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

5 is a flowchart illustrating a foreign material detection procedure in a wireless power transmission system according to an embodiment of the present invention.

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

FIG. 7 is a diagram illustrating the transmission antenna configuration of FIG. 6 according to an embodiment of the present disclosure.

8 is a block diagram illustrating a structure of a wireless power receiver interoperating with the wireless power transmitter of FIG. 6 according to an embodiment of the present invention.

9 is a view for explaining a power transmission control method according to whether foreign matter is detected in a wireless power transmitter according to the prior art.

10A to 10D are diagrams for describing a packet format according to an embodiment of the present invention.

11 is a flowchart illustrating a wireless power transmission method in a wireless power transmitter according to an embodiment of the present invention.

12 is a flowchart illustrating a wireless power transmission method in a wireless power transmitter according to another embodiment of the present invention.

13 is a diagram for describing a wireless power transmission method in a wireless power transmitter according to another embodiment of the present invention.

14 is a view for explaining a wireless power transmission method in a wireless power transmitter according to another embodiment of the present invention.

15 is a diagram for describing a wireless power transmission method in a wireless power transmitter according to another embodiment of the present invention.

16 is a diagram for describing a resonance frequency bandwidth according to an exemplary embodiment of the present invention.

17 is a flowchart illustrating a foreign material detection procedure using a resonance frequency bandwidth in a wireless power transmission system according to an embodiment of the present invention.

FIG. 18 is a diagram for describing a pattern of change in resonant frequency bandwidth depending on whether foreign materials are disposed.

19 is a view for explaining the structure of a wireless power transmission apparatus according to an embodiment of the present invention.

20 shows a result of a foreign material detection experiment for various foreign materials by transmitter type.

FIG. 21 shows a result of a foreign substance detection experiment for various foreign substances by receiver type.

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

In addition, the suffixes "module" and "unit" for components used in the following description may be implemented as hardware components, including, for example, circuit elements, microprocessors, memory, sensors, and the like. This is merely an example, and some or all of the components may be implemented in software.

In the description of the embodiments, where it is described as being formed on the "top" or "bottom" of each component, the top (bottom) or the bottom (bottom) is the two components are in direct contact with each other or One or more other components are all included disposed between the two components. In addition, when expressed as "up (up) or down (down)" may include the meaning of the down direction as well as the up direction based on one component.

In the description of the embodiment, a device equipped with a function for transmitting wireless power on the wireless charging system is a wireless power transmitter, a wireless power transmitter, a wireless power transmitter, a wireless power transmitter, a transmitter, a transmitter, a transmitter for convenience of description. , A transmitter side, a wireless power transmitter, a wireless power transmitter, and the like will be used interchangeably.

In addition, as a representation of a device equipped with a function for receiving wireless power from the wireless power transmitter, for convenience of description, a wireless power receiver, a wireless power receiver, a wireless power receiver, a wireless power receiver, a receiver terminal, a receiver, Receivers, receivers and the like can be used interchangeably.

The transmitter according to the present invention may be configured in a pad form, a cradle form, an access point (AP) form, a small base station form, a stand form, a ceiling buried form, a wall hanging form, and the like. You can also transfer power. To this end, the transmitter may comprise at least one wireless power transmission means.

Herein, the wireless power transmission means may use various wireless power transmission standards based on an electromagnetic induction method that generates a magnetic field in the power transmitter coil and charges using the electromagnetic induction principle in which electricity is induced in the receiver coil under the influence of the magnetic field.

For example, the wireless power transmission standard may include, but is not limited to, the standard technology of the electromagnetic induction method defined by the Wireless Power Consortium (WPC) Qi and the Power Matters Alliance (PMA), which are wireless charging technology standard organizations.

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

The receiver according to the present invention is a mobile phone, smart phone, laptop computer, digital broadcasting terminal, PDA (Personal Digital Assistants), PMP (Portable Multimedia Player), navigation, MP3 player, electric It may be used in small electronic devices such as a toothbrush, an electronic tag, a lighting device, a remote control, a fishing bobber, a wearable device such as a smart watch, and the like, but is not limited thereto. It is enough.

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

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

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

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

For example, the information exchanged between the wireless power transmitter 10 and the wireless power receiver 20 may include control information as well as status information of each other.

Here, the status information and control information exchanged between the transmitting and receiving end will be more clear through the description of the embodiments to be described later.

The in-band communication and the out-of-band communication may provide bidirectional communication, but are not limited thereto. In another embodiment, the in-band communication and the out-of-band communication may provide one-way communication or half-duplex communication.

For example, the unidirectional communication may be performed by the wireless power receiver 20 only transmitting information to the wireless power transmitter 10, but is not limited thereto. The wireless power transmitter 10 may only be transmitted to the wireless power receiver 20. It may be to transmit information.

In the half-duplex communication method, bidirectional communication between the wireless power receiver 20 and the wireless power transmitter 10 is possible, but at one time, only one device may transmit information.

The wireless power receiver 20 according to an embodiment of the present invention may obtain various state information of the electronic device 30.

For example, the state 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, and the like. The information may be obtained from the electronic device 30 and may be utilized for wireless power control.

In particular, the wireless power transmitter 10 according to an embodiment of the present invention may transmit a predetermined packet indicating whether to support fast charging to the wireless power receiver 20.

The wireless power receiver 20 may notify the electronic device 30 when it is determined that the connected wireless power transmitter 10 supports the fast charging mode.

The electronic device 30 may indicate that fast charging is possible through predetermined display means provided, for example, it may be a liquid crystal display.

For example, as illustrated by reference numeral 200a, the wireless power receiver 20 may be configured with a plurality of wireless power receivers, and a plurality of wireless power receivers are connected to one wireless power transmitter 10 so that the wireless Charging may also be performed.

In this case, the wireless power transmitter 10 may distribute and transmit power to the 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 by using different frequency bands allocated for each wireless power receiver.

In this case, the number of wireless power receivers that can be connected to one wireless power transmitter 10 is based on at least one of the required power amount for each wireless power receiver, the state of charge of the battery, the power consumption of the electronic device, and the available power of the wireless power transmitter. Can be determined adaptively.

As another example, as shown 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 simultaneously receive power from the connected wireless power transmitters and perform charging.

In this case, the number of wireless power transmitters connected to the wireless power receiver 20 may be adaptively based on the required power of the wireless power receiver 20, the state of charge of the battery, the power consumption of the electronic device, and the available power of the wireless power transmitter. Can be determined.

For example, the wireless power transmitter may be equipped with three transmitting

coils

111, 112, and 113. Each transmission coil may overlap some other area with another transmission coil, and the wireless power transmitter may detect a

predetermined detection signal

117, 127 for detecting the presence of the wireless power receiver through each transmission coil, for example, Digital ping signals are sent sequentially in a predefined order.

As shown in FIG. 3, the wireless power transmitter sequentially transmits the detection signal 117 through the primary detection signal transmission procedure illustrated in FIG. 110, and receives a signal strength indicator from the wireless power receiver 115. The strength indicator 116 can identify the received

transmission coils

111, 112.

Subsequently, the wireless power transmitter sequentially transmits the detection signal 127 through the secondary detection signal transmission procedure shown in FIG. 120, and transmits power among the transmission coils 111 and 112 where the signal strength indicator 126 is 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 that power can be sent through the identified transmitting coil-i.e. wireless charging is made. .

As shown in FIG. 3, the reason why the wireless power transmitter performs two sensing signal transmission procedures is to more accurately identify which transmitting coil is well aligned with the receiving 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. Based on the signal strength indicator 126 received at each of the first transmitting coil 111 and the second transmitting coil 112 selects the best-aligned transmitting coil and performs wireless charging using the selected transmitting coil. .

Referring to FIG. 4, power transmission from a transmitter to a receiver according to an embodiment of the present invention is largely selected as a selection phase 410, a ping phase 420, an identification and configuration phase. , 430, a negotiation phase 440, a calibration phase 450, a power transfer phase 460, and a renegotiation phase 470.

The selection step 410 is a step of transitioning when a specific error or a specific event is detected while initiating or maintaining power transmission, for example, including reference numerals S402, S404, S408, S410 and S412. Can be.

Here, specific errors and specific events will be apparent from the following description.

In addition, in the selection step 410, the transmitter may monitor whether an object exists 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 of an analog ping signal, and based on the current change of the transmitting coil (or primary coil), It can detect whether an object exists in the active area. Here, the active area may mean an area in which the receiver is arranged to enable wireless charging.

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

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

If an object is detected in the selection step 410, the wireless power transmitter corresponds to an LC resonant circuit provided, for example, the LC resonant circuit may comprise 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 the wireless power receiver is disposed along with the foreign matter in the charging area.

Here, the quality factor value may be measured prior to entering the ping step 420. In addition, the quality factor value may be measured while power transmission through the transmitting coil is suspended.

Quality factor values can be measured in a variety of ways.

For example, the quality factor value may be measured based on a voltage decay rate of a pulse signal for a unit time in a time domain.

As another example, the quality factor value may be measured based on an energy concentration rate at a resonance point in the frequency domain.

As another example, the quality factor value may be measured based on the voltage amplification factor in the resonant circuit.

The wireless power transmitter according to an embodiment may measure a quality factor value for a predefined reference operating frequency. Here, the reference operating frequency may be 100 KHz.

The wireless power transmitter according to another embodiment may measure the quality factor value in a predetermined frequency unit within an operating frequency band available for wireless power transmission.

In this case, the wireless power transmitter may identify an operating frequency value having the maximum value among the quality factor values measured in the operating frequency band, and store the same in the memory.

For convenience of description, a frequency having a maximum quality factor value in an operating frequency band will be referred to as a quality factor peak frequency or simply a peak frequency or resonance frequency for convenience of explanation.

The measurement pattern and quality factor peak frequency of the quality factor value measured corresponding to the operating frequency band may be different depending on the type of the wireless power transmitter.

In particular, the quality factor values measured using the transmitters used for authenticating the receiver for the same operating frequency, the business card 'Authentication Transmitter' and the LCR meter for convenience of description, are measured by commercial transmitters. It may be different from.

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 procedure is normally completed, the wireless power transmitter may enter a negotiation step 440 (S405).

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

When the wireless power transmitter enters 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 the quality factor threshold based on the received reference quality factor value.

Thereafter, the wireless power transmitter may compare the measured quality factor value with the quality factor threshold to determine the presence of foreign substances.

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

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

The foreign substance is compared by comparing the quality factor value received in the negotiation step 440 with the quality factor value corresponding to the reference operating frequency measured before the ping step 420, hereinafter, the business card as the current quality factor value for convenience of description. It can be determined whether it exists or not.

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

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

The transmission coil may reduce inductance and / or series resistance components in the transmission coil according to changes in the surrounding environment, thereby changing (shifting) the resonance frequency in the transmission coil. That is, the quality factor peak frequency, 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 (shield) having a high permeability, the high permeability may increase the inductance value measured at the transmitting coil. On the other hand, the foreign material of the metal type can reduce the inductance value.

In general, for an LC resonant circuit, the resonant frequency (f_resonant) is

Is calculated.

If only the wireless power receiver is placed in the charging region of the transmitter, the L value is increased so that the resonance frequency becomes small. In other words, the resonant frequency is shifted (shifted) to the left on the frequency axis.

On the other hand, when the foreign material is disposed in the charging region of the transmitter, the resonance frequency increases because the L value is reduced. That is, the resonant frequency is shifted (shifted) to the right on the frequency axis.

The transmitter according to another embodiment of the present invention may determine whether there is a foreign material disposed in the charging region based on the change in the quality factor peak frequency.

The transmitter is referred to as a preset quality factor peak frequency corresponding to the transmitter type, hereinafter referred to as 'reference quality factor peak frequency (pf_reference)' or 'reference peak frequency' or 'reference resonance frequency'. Information about the business card can be obtained from the receiver or held in a predetermined recording area in advance.

When the transmitter detects that the object is placed in the charging region, the transmitter may measure 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 or 'measured resonance frequency'.

In the negotiation step 430, the transmitter may determine the presence of foreign matter based on the reference quality factor peak frequency and the measurement 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.

For example, the transmitter may identify and configure 430 the information about its transmitter type to the receiver.

The receiver may read a prestored reference quality factor peak frequency in a corresponding memory in response to the received transmitter type information, and transmit information about the read reference quality factor peak frequency to the transmitter.

The transmitter according to another embodiment of the present invention may determine whether a foreign substance exists by using both a foreign substance detection method based on a quality factor peak frequency and a foreign substance detection method based on a quality factor value.

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

On the other hand, if the difference between the two quality factor values exceeds 10%, the transmitter may immediately determine that there is a foreign object.

In another embodiment, when it is determined that there is no foreign matter as a result of comparing the quality factor threshold value determined based on the reference quality factor value corresponding to the transmitter type with the measured quality factor value, the transmitter may determine the reference quality factor peak frequency corresponding to the transmitter type. The presence of foreign matter may be determined by comparing the measured quality factor peak frequencies.

If the transmitter is not easy to detect foreign matter based on the quality factor value, the transmitter may request information about the reference quality factor peak frequency corresponding to the transmitter type from the identified receiver.

Subsequently, when the information about the reference quality factor peak frequency is received from the receiver, the transmitter may determine whether the foreign substance is present using the reference quality factor peak frequency and the measured quality factor peak frequency.

Through this, the transmitter can more accurately detect the foreign matter disposed in the charging region.

When the transmitter detects an object, the transmitter enters the ping step 420 to wake up the receiver and transmits a digital ping for identifying whether the detected object is a wireless power receiver.

If in ping step 420 the transmitter does not receive a response signal (eg, a signal strength packet) to the digital ping from the receiver, it may transition back to selection step 410.

Also, in ping step 420, the transmitter may transition to selection step 410 upon receiving a signal from the receiver indicating that power transmission is complete, i.e., a charging complete packet.

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

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

The receiver may request the transmitter for information about the transmitter type at the identification and configuration step 430, and the transmitter may transmit information about the transmitter type to the receiver according to the receiver's request.

In addition, in the identification and configuration step 430, the transmitter may receive an unexpected packet, a desired packet has not been received for a predefined time, a packet transmission error, or a power failure. If a transfer contract is not established (no power transfer contract), it may transition to selection step 410.

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

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

On the other hand, if the result of the check does not require negotiation, the transmitter may immediately enter the power transmission step (460).

According to an embodiment of the present invention, when the wireless power receiver 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. It may enter 460.

The wireless power transmitter may periodically perform a foreign matter detection procedure after entering the power transmission step 460.

Here, the foreign matter detection procedure may be a foreign matter detection procedure based on the quality factor value, but is not limited thereto, and a foreign matter 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 there is a foreign matter by comparing a difference between the transmission power of the wireless power transmitter and the reception 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) including a reference quality factor value. Alternatively, the FOD Status Packet including the 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 the quality factor threshold for detecting the foreign matter based on the reference quality factor value corresponding to the transmitter type.

The transmitter may determine the quality factor peak frequency threshold for the foreign material detection based on the reference quality factor peak frequency value corresponding to the transmitter type.

The transmitter determines the determined quality factor threshold and / or the determined quality factor peak frequency threshold by means of the measured quality factor value—meaning the quality factor value measured before the ping step 420—and / or the measured quality factor peak frequency. The foreign matter disposed in the filling region may be detected by comparison with the value.

The transmitter may control the power transmission according to the foreign matter detection result. 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 interrupted, but is not limited thereto.

The transmitter may detect the foreign matter disposed in the charging region by comparing the determined quality factor peak frequency threshold value and the measured quality factor peak frequency value. The transmitter may control the power transmission according to the foreign matter detection result.

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 interrupted, but is not limited thereto.

If a foreign object is detected, the transmitter may receive an end of charge message from the receiver, and thus may enter the selection step 410.

According to another embodiment of the present invention, when a foreign matter is detected in the negotiation step 440, the transmitter may enter the power transmission step 460 (S415).

On the other hand, if the foreign matter is not 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, when no foreign matter is detected, when the transmitter enters the calibration step 450, the transmitter determines the strength of the received power at the receiver, and measures the power loss between the transmitter and the receiver to determine the strength of the power to be transmitted at the transmitter. can do.

For example, the transmitter may determine the received power strength to the receiver based on the received power strength information fed back from the receiver during power transmission. That is, the transmitter may predict (or calculate) the power loss based on the difference in intensity between the transmit power at the transmitter and the receive power at the receiver in the correction step 450.

In the power transfer step 460, the transmitter receives an unexpected packet, an outgoing desired packet for a predefined time, or a violation of a preset power transfer contract. transfer contract violation), if the filling is completed, may enter the selection step (410) (S410).

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

The power transmission contract may be set based on state and characteristic information of the transmitter and the receiver.

For example, the transmitter state information may include information on the maximum transmittable power, information on the maximum acceptable number of receivers, and the like. The receiver state information may include information on required power.

The wireless power transmitter according to an embodiment of the present invention may operate in any one of the second power transfer mode among the first power transfer 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 settable in accordance with the second power transfer mode may be greater than the guaranteed power settable in the first power transfer mode.

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

Referring to FIG. 5, when an object is detected in the selection step, the wireless power transmitter 510 may measure a 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 sensing signal transmission procedure described with reference to FIG. 3 (S503).

When the wireless power receiver 520 is detected, the wireless power transmitter 510 may enter an identification and configuration step and receive an identification packet and a configuration packet (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 substance exists based on a reference quality factor value included in the foreign substance detection status packet (S507).

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

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

The wireless power transmitter 510 may transmit an ACK response or NACK response or ND (not defined) response to the wireless power receiver 520 according to the foreign matter detection result (S509).

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

Here, the power of a certain intensity or more may be 5W as a reference, but is not limited thereto. Designed by those skilled in the art and an electronic device equipped with the wireless power receiver 510 and / or a battery / load connected to the wireless power receiver 510 may be used. Can be defined differently accordingly.

Referring to FIG. 6, the wireless power transmitter 600 includes a controller 610, a gate driver 620, an inverter 630, a transmission antenna 640, a power 650, and a power supply. Supply 660, sensor 670 and demodulator 680 may be configured to include.

The power supply 660 may convert DC power or AC power applied from the power supply 650 and provide the converted power to the inverter 630. Hereinafter, for convenience of description, a voltage supplied from the power supply 660 to the inverter 630 will be referred to as an inverter input voltage or a V rail.

The power supply 660 may include at least one of an AC / DC converter and a DC / DC converter, depending on the type of power applied from the power source 650. .

For example, the power supply 660 may be a switching mode power supply (SMPS), and may use a switch control method of converting AC power into DC power using a switching transistor, a filter, and a rectifier. . Here, the rectifier and the filter may be configured independently and disposed between the AC power source and the SMPS.

SMPS is a power supply that controls the on / off time ratio of semiconductor switch element and supplies the stabilized output DC power to the device or circuit element. It is widely used in equipment and equipment.

In many cases, the stability and precision of electronic circuit operation depends on the quality of the power supply. In general, there are two methods of converting a stable power supply from a battery and a commercial AC power supply, a series regulator method and a switched mode method.

Linear control schemes used in TV receivers, CRT monitors, and the like have simple peripheral circuits and are inexpensive, but have disadvantages such as high heat generation, low power efficiency, and large volume.

On the other hand, the switching mode method has the advantages of almost no heat generation, high power efficiency, and small volume. However, the switching mode method is expensive, complicated circuit, and output noise and electromagnetic interference due to high frequency switching.

As another example, a variable variable switching mode power supply (SMPS) may be used as the power supply 660. The variable SMPS generates DC voltages by switching and rectifying AC voltages in the tens of Hz bands output from an AC power supply.

A variable SMPS may output a DC voltage of a constant level or adjust the output level of the DC voltage according to a predetermined control of a Tx controller.

The variable SMPS controls the supply voltage according to the output power level of the power amplifier, i.e., the inverter 530, so that the power amplifier of the wireless power transmitter can always operate in the highly efficient saturation region, thus providing maximum efficiency at all output levels. Can be maintained.

If a commercially available SMPS is used instead of the variable SMPS, a variable DC / DC converter (Variable DC / DC) may be additionally used.

Commercial SMPSs and variable DC / DC converters can control the supply voltage according to the power amplifier's output power level so that the power amplifier can operate in a highly efficient saturation region, allowing maximum efficiency at all output levels. In one embodiment, the power amplifier may be a Class E type, but is not limited thereto.

The inverter 630 converts the DC voltage V_rail of a constant level by a switching pulse signal of a few MHz to several tens of MHz bands, that is, a pulse width modulated signal, received through the gate driver 620. The AC power to be transmitted wirelessly can be generated by converting to.

In this case, the gate driver 620 may generate a plurality of PWM signals SC_0 to SC_N for controlling a plurality of switches included in the inverter 630 using the reference clock signal Ref_CLK supplied from the controller 610. Can be.

Here, when the inverter 630 includes a half bridge circuit, N is 1, and when the inverter 630 includes a full bridge circuit, N may be 3, but is not limited thereto. Inverter 630 Depending on the design of the different number of PWM signals for each inverter type may be supplied.

For example, in the embodiment of FIG. 6, when the inverter 630 includes a full bridge circuit including four switches, the inverter 630 may include four PWM signals SC_0, SC_1, for controlling each switch. SC_2 and SC_3 may be received from the gate driver 620.

In contrast, in the embodiment of FIG. 6, when the inverter 630 includes a half bridge circuit including two switches, the inverter 630 gates two PWM signals SC_0 and SC_1 to control each switch. Receive from driver 620.

The transmit antenna 640 is at least one power transmission antenna (not shown) for transmitting wirelessly an AC power signal received from the inverter 630-for example, an LC resonant circuit-and a matching circuit for impedance matching (not shown). It may be configured to include).

In addition, when the transmitting antenna 640 is provided with a plurality of transmitting coils, the transmitting antenna 640 may further include a coil selecting circuit (not shown) for selecting a transmitting coil to be used for wireless power transmission among the plurality of transmitting coils. have.

The sensor 670 may be a power / voltage / current strength input from the inverter 630 or (and) power / voltage / current strength flowing through a transmission coil provided in the transmission antenna 640, and a specific location inside the wireless power transmitter. And various sensing circuits for measuring temperature and / or temperature changes, such as, for example, may include transmission coils, charging beds, control circuit boards, and the like. Here, the information sensed by the sensor 670 may be transferred to the controller 610.

In addition, the sensor 670 may measure and transmit the strength of the current flowing through the transmission coil to the controller 610 while the analog ping is transmitted in the selection steps 410 and 510. The controller 610 may detect the presence or absence of an object disposed in the charging area by comparing the intensity information of the power flowing through the transmission coil with a predetermined reference value in the selection step.

When the wireless power transmitter 600 performs in-band communication with the wireless power receiver, the wireless power transmitter 600 may include a demodulator 680 connected to the transmit antenna 640.

The demodulator 680 may demodulate and transmit the amplitude modulated in-band signal to the controller 610.

For example, the controller 610 may check whether a signal strength indicator corresponding to the digital ping transmitted based on the demodulation signal received from the demodulator 680 is received.

When the controller 610 detects an object disposed in the charging region in the selection step 410, the controller 610 enters the ping step 420 and controls the digital ping to be transmitted through the transmission antenna 640.

When the controller 610 detects an object disposed in the charging area in the selection step 410, the controller 610 may suspend power transmission and measure a quality factor value before entering the ping step. Here, the measured quality factor value may be maintained in a predetermined memory (not shown) provided in the wireless power transmitter 600.

When the reception of the signal strength indicator is confirmed in the ping step, the controller 610 may stop the digital ping transmission and enter the identification and configuration step 430 to receive the identification packet and the configuration packet.

When the power transmission end packet is received after entering the power transmission step 460, the controller 610 may stop the power transmission and enter the selection step 410.

In addition, when there is a foreign object in the charging area, the controller 610 may stop the power transmission and enter the selection step 410.

Also, the controller 610 may calculate (or estimate) power loss on the wireless power transmission path based on the received signal strength packet received from the wireless power receiver.

The controller 610 may determine the presence or absence of the foreign matter based on the calculated (or estimated) power loss.

In addition, the controller 610 may measure the temperature change based on temperature sensing information received from the sensor 670 or temperature measurement information received from the wireless power receiver. The controller 610 may determine the presence of foreign matter based on the measured temperature change.

In addition, the controller 610 may perform a foreign matter presence determination process based on the temperature change based on the result of the determination of the presence of foreign matter based on the power loss.

In addition, when the controller 610 according to the present invention receives the FOD status packet in the negotiation step 440, the controller 610 determines a threshold value for the foreign material detection based on the received FOD status packet, and the foreign material exists based on the determined threshold value. You can also determine whether or not.

The controller 610 stops the power transmission and enters the selection step 410 when the power transmission termination packet including the ripping code or the overheating code is received through the demodulator 680 in the power transmission stage 460. You can also run a timer.

The controller 610 may suppress the analog ping transmission and beep signal output until the driven ripping timer expires. Thereafter, when the ripping timer expires, the controller 610 may enter the ping step 420 and control the digital ping to be transmitted through the transmit antenna 640.

After the identification and configuration of the detected receiver is completed, the controller 610 may return to the selection step 410 after resetting the ripping time if a power transmission end packet including a ripping code or an overheating code is received.

An operation mode of the wireless power transmitter 600 according to an embodiment of the present invention may include a first power transmission mode and a second power transmission mode.

The controller 610 may operate in one of the first power transfer mode and the second power transfer mode based on the determination result of the foreign matter in the negotiation step 440.

In this case, the guaranteed power (or the maximum transmit power) may be set to be larger in the second power transfer mode than in the first power transfer mode.

For example, the guaranteed power in the first power transfer mode may be 5W, and the guaranteed power in the second power transfer mode may be 15W, but is not limited thereto. Note that the power may be set differently.

If the foreign matter is present as a result of the determination of the presence of the foreign matter in the negotiation step 440, the controller 610 sets the guaranteed power level from the second level corresponding to the second power transfer mode to the first power transfer mode. Can be changed to 1 level.

That is, if the controller 610 determines that the foreign matter exists in the negotiation step 440, the controller 610 may adjust the guaranteed power downward. Through this, it is possible to prevent the device from being damaged due to overheating due to a foreign material during high power transmission.

When the controller 610 enters the first power transfer mode, the controller 610 may control the correction step 450 of FIG. 4 not to be performed.

If the foreign matter is present in the charging area, but the correction step 450 is performed in the first power transfer mode, the foreign matter detection method based on the power loss has a problem of inferior accuracy.

Generally, the correction step 450 is a procedure performed assuming that there is no foreign matter. Therefore, if the correction step 450 is performed despite the presence of the foreign matter in the charging region, the foreign matter detection method based on the power loss has a problem that the accuracy of the foreign matter is not reliable.

If the foreign matter is not detected through the foreign matter detection method based on the power loss and / or the temperature change after the entry into the first power transfer mode, the controller 610 of FIG. The renegotiation stage 470 may be entered.

The controller 610 may change the operation mode according to the determined power transmission contract when the power transmission contract is determined according to the renegotiation result with the wireless power receiver.

For example, the power transmission contract may include guaranteed power, and the controller 610 may change and set the guaranteed power through a renegotiation procedure with the wireless power receiver.

If, as a result of the renegotiation, the guaranteed power required by the wireless power receiver is changed from the first guaranteed power corresponding to the first power transfer mode to the second guaranteed power corresponding to the second power transfer mode, the controller 610 operates in the operating mode. May switch from the first power transfer mode to the second power transfer mode.

As described in the above embodiments, the wireless power transmitter 600 according to the present invention has an advantage of continuously charging even when it is determined that the foreign matter exists, even though the foreign matter does not exist.

In detail, the wireless power transmitter 600 does not stop charging immediately without determining that the foreign matter exists even though the actual foreign matter does not exist during the operation in the initial second power transfer mode, and removes the power transfer mode. The charging may be maintained by switching from the second power transfer mode to the first power transfer mode.

As an example, the wireless power transmitter 600 may determine that there is a foreign matter in the charging area according to the alignment state between the transmitting coil and the receiving coil even when the wireless power receiver is disposed without the foreign material in the charging area.

The wireless power transmitter 600 according to the present invention has an advantage of detecting foreign matter more accurately by performing an additional foreign matter detection procedure even after switching to the first power transfer mode.

Here, the additional foreign matter detection procedure may include at least one of a foreign matter detection procedure based on power loss and a foreign matter detection procedure based on temperature change.

Referring to FIG. 7, the transmission antenna 640 may include a coil selection circuit 710, a coil assembly 720, and a resonant 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 inverter 630 output current I_coil to any one or at least one of the transmission coils included in the coil assembly 720.

As an example, the coil selection circuit 710 may include first to Nth switches having one end connected to an inverter output terminal and the other end connected to a coil corresponding thereto.

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

The demodulator 680 can demodulate and pass the signal between the coil assembly 720 and the resonant capacitor 730, where the signal is an amplitude modulated signal, to the controller 610.

Referring to FIG. 8, the wireless power receiver 800 includes a reception antenna 810, a rectifier 820, a DC / DC converter 830, a switch 840, a load 850, and a sensing unit ( 860, a modulator 870, and a main controller 870 may be configured.

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

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

AC power transmitted by the wireless power transmitter 600 may be delivered to the rectifier 820 through the receive antenna 810. The rectifier 820 may convert AC power received through the reception antenna 810 into DC power and transmit the DC power to the DC / DC converter 830.

The DC / DC converter 830 may convert the intensity of the output DC power of the rectifier 820 into the DC power at a specific intensity required by the load 850.

The sensing unit 840 may measure the output DC power strength of the rectifier 820 and provide the measurement result to the main controller 880.

The main controller 880 may perform power control based on the output DC power of the rectifier 820.

In addition, the sensing unit 840 may measure the strength of the current applied to the reception antenna 810 according to the wireless power reception, and may transmit the measurement result to the main controller 880.

In addition, the sensing unit 840 may measure the internal temperature of the wireless power receiver 800 or the electronic device equipped with the wireless power receiver 800, and provide the measured temperature value to the main controller 880.

For example, the main controller 880 may determine whether an overvoltage occurs by comparing the measured intensity of the rectifier output DC power with a predetermined reference value. As a result of the determination, when the overvoltage is generated, the main controller 880 may transmit a predetermined packet indicating that the overvoltage has occurred to the wireless power transmitter 600 through the modulator 870.

When the packet is received from the main controller 880, the modulator 870 may generate an amplitude modulated signal corresponding to the received packet by using the AC power received through the receive antenna 810 and the provided switch. In this case, the wireless power transmitter 600 may demodulate the demodulator 680 provided with the signal modulated by the wireless power receiver 800.

As an example, when the signal strength packet is received from the main controller 880 in the ping step, the modulator 870 may amplitude modulate the digital ping received through the reception antenna 1010 corresponding to the received signal strength packet. .

The modulator 870 according to an embodiment may be provided with a modulation switch for amplitude modulating the AC power signal received through the reception antenna 810. In this case, the main controller 880 may directly control the modulation switch by transmitting a pulse width modulated signal corresponding to the transmission target packet to the modulator 870.

In addition, when the intensity of the rectifier output DC power is greater than or equal to a predetermined reference value, the main controller 880 may determine that a detection signal, for example, a digital ping, is received. The signal strength packet may be controlled to be transmitted to the wireless power transmitter through the modulator 870.

For example, the main controller 880 controls the switch 840 when the internal temperature exceeds a predetermined reference value, for example, by switching off, so that the output DC power of the DC / DC converter 830 is applied to the load 850. You can also control the delivery. In this case, the main controller 880 may transmit the power transmission stop packet including the overheat code to the wireless power transmitter 600 through the modulator 1070.

As another example, the main controller 880 may be linked with a power management device that controls the internal power of the electronic device in which the wireless power receiver 800 is mounted, for example, a power management IC (PMIC).

In this case, the output DC power of the DC / DC converter 1030 may be transferred to the power management device through the switch 840, and the power management device may control the charging of the battery and the power supply to the internal parts of the electronic device. .

The power management device may provide the battery charge state information to the main controller 880. The main controller 880 may determine whether charging is performed based on the battery charge state information and the internal temperature information.

When the wireless power receiver 800 according to an embodiment of the present invention enters the negotiation step 440, the wireless power receiver 800 may generate a foreign matter detection status packet and transmit the generated foreign matter detection status packet to the wireless power transmitter 600.

Here, the foreign matter detection status packet may include a reference quality factor value.

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

The wireless power receiver 800 according to the embodiment of FIG. 8 may further include a demodulator (not shown) for demodulating a packet transmitted by the wireless power transmitter 600.

Through this, the wireless power transmitter 600 and the wireless power receiver 800 may perform bidirectional communication. According to an embodiment, the bidirectional communication may be time division communication in which packet transmission possible time in the wireless power transmitter and packet transmission time in the wireless power receiver are divided, but are not limited thereto.

When the wireless power transmitter receives the negotiation request packet from the wireless power receiver, the wireless power transmitter may enter a negotiation step 440 by transmitting a grant packet.

Referring to FIG. 9, in a negotiation step 440, the wireless power transmitter may receive a Foreign Object Detection (FOD) Status Packet (FOD) from the wireless power receiver (S901).

For example, the wireless power transmitter may receive a foreign object detection status packet including a reference quality factor value.

The wireless power transmitter may determine whether there is a foreign substance (S902). Herein, the wireless power transmitter determines the quality factor threshold determined based on the quality factor value measured after the object detection in the selection step 410 and before the entry into the ping step 420 and the reference quality factor value received in the negotiation step 440. By comparing the values, it is possible to determine the presence of foreign substances.

As a result of the determination, if there is no foreign matter, the wireless power transmitter may transmit an ACK signal to the corresponding wireless power receiver (S903).

Thereafter, the wireless power transmitter may receive a guaranteed power packet including information about guaranteed power required by the wireless power receiver (S904).

The wireless power transmitter may receive a negotiation end packet from the wireless power receiver (S905).

When the negotiation end packet is received, the wireless power transmitter may enter the negotiation step 450 from the negotiation step 440.

The wireless power transmitter may enter a calibration step 450 and perform a predetermined calibration procedure (S906).

When the power transmission contract is completed through the calibration procedure, the wireless power transmitter may enter the power transmission step 460 and start charging (S907).

If, as a result of the determination in step 902, foreign matter exists, the wireless power transmitter may transmit a NACK signal in response to the foreign matter detection status packet (S908).

When the wireless power receiver receives a NACK signal in response to a foreign object detection status packet, the power at its output may be a predetermined reference value, e.g., 5 W, until the power signal received from the wireless power transmitter is completely removed. However, the present invention is not limited thereto.

The wireless power transmitter may stop power transmission within a predefined time after transmitting the NACK signal, for example, 5 seconds (S909).

If the power transmission is stopped, the wireless power transmitter may enter the selection step 410 (S910).

The transmission of power in the second power transfer mode in the state where the foreign matter is disposed in the charging area may increase the risk of heat generation of the device.

Therefore, when the conventional wireless power transmitter determines that the foreign substance exists, the wireless power transmitter blocks the entry to the power transmission step 460 and stops the power transmission within a predefined time, and then enters the selection step 410.

However, the wireless power transmitter has a quality factor cross calibration error due to the measurement error of the provided LCR meter, the design of the instrument of the wireless power transmitter and the wireless power receiver, and the design difference of the coils mounted on each of the wireless power transmitter. The actual foreign matter does not exist but the foreign matter exists due to the separation distance between the receiving coil and the receiving coil, that is, the Z distance and the position of the wireless power receiver disposed in the charging region, that is, the XY displacement.

If there is no actual foreign matter, unconditionally stopping the power transmission and returning to the selection step may cause serious user inconvenience.

In particular, the wireless power receiver to be applied to smart phones, etc. may be designed to apply a high permeability shielding agent to reduce the thickness of the product, and to reduce the thickness of the receiving coil as small as possible.

In this case, the resistance R becomes very large and the quality factor Q can be very small. In addition, if the metal housing is applied to the product quality factor Q can be further lowered.

This may increase the error probability for determining whether there is a foreign substance in the wireless power transmitter.

For example, if an error regarding the determination of the presence of a foreign substance occurs, even though the smartphone is placed in the charging region, a situation where the quality factor Q is measured and judged to be a foreign substance, not only the foreign substance but also the smartphone is also placed in the charging region. It may include such a situation.

Accordingly, there is a need for a power transmission control method in a wireless power transmitter capable of minimizing user inconvenience while preventing device damage due to overheating in order to solve the above problems of the prior art.

Although the wireless power transmitter 10 and the wireless power receiver 20 according to an embodiment of the present invention may exchange packets through in-band communication, this is only one embodiment. Can also be exchanged.

Referring to FIG. 10A, a packet format 1000 used for exchanging information between a wireless power transmitter 10 and a wireless power receiver 20 may be used to obtain synchronization for demodulation of a corresponding packet and to identify an exact start bit of the corresponding packet. Preamble (1010) field for the header, Header (header, 1020) field for identifying the type of the message included in the packet, Message for transmitting the contents (or payload) of the packet (Message, 1030) field and a checksum (1040) field for checking whether an error has occurred in the packet.

The packet receiving end may identify the size of the message 1030 included in the packet based on the header 1020 value.

In addition, the type of transmittable packet for each step illustrated in FIG. 4 may be defined by a header 1020 value, and some header 1020 values may be defined to be shared at different stages of a wireless power transmission procedure. Can be. For example, an end power transfer packet for stopping power transmission of the wireless power transmitter may be defined as the same header 1020 in the ping step 420 and the power transfer step 460.

The message 1030 includes data to be transmitted at the transmitting end of the packet.

For example, the data included in the message 1030 field may be a report, a request, or a response to the counterpart, but is not limited thereto.

The packet format 1000 according to another embodiment of the present invention may further include at least one of transmitter identification information for identifying a transmitter that transmitted the packet, and receiver identification information for identifying a receiver for receiving the packet. have.

Here, the transmitter identification information and the receiver identification information may include IP address information, medium access control (MAC) address information, product identification information, and the like, but are not limited thereto and may distinguish the receiver and the transmitter from a wireless charging system. Information is enough.

The packet format 1000 according to another embodiment of the present invention may further include predetermined group identification information for identifying the corresponding reception group when the packet is to be received by a plurality of devices.

If the header 1020 is a value corresponding to a foreign object detection status packet, the message 1030 field according to an embodiment of the present invention is shown in FIGS. 10A and 10B.

It may have a length of 2 bytes and includes a 6-bit Reserved (1031) field, a 2-bit Mode (Mode) 1032 field, and a 1-byte long Reference FOD Value (1033) field. It can be configured to include.

For the convenience of the description below, the reference foreign matter detection value 1033 is used interchangeably with the “reference value”.

For example, referring to FIG. 10A, if the message 1030 field of the foreign matter detection status packet is set to binary number '00', the reference foreign matter detection value 1033 may be set as shown in reference numeral 1050. Reference Resonance Quaility Factor Value is recorded in the field, and if the mode 1033 field is set to binary '01', the Reference Resonance Frequency is recorded in the reference foreign matter detection value 1033 field. Can be.

Here, the reference resonance quality factor and the reference resonance frequency are positive integer values, and the reference resonance quality factor may be defined as a quality factor measured corresponding to the reference resonance frequency.

As another example, referring to FIG. 10B, the message 1030 field of the foreign matter detection status packet may be set to the reference foreign matter detection value 1033 when the mode 1032 field is set to binary '00', as shown at 1060. Reference Resonance Quaility Factor Value is recorded in the) field, and if the mode 1033 field is set to binary '01', the Reference Resonance Frequency is recorded in the reference foreign substance detection value 1033 field. Can be.

Here, the Reference Resonance Quaility Factor Value and the Reference Resonance Frequency may be positive integer values.

As an example, if the reference foreign matter detection value 1033 field is a reference resonance frequency, the actual frequency value may be calculated by adding 36 divided by the value of the reference foreign matter detection value 1033 field divided by two. Therefore, the reference resonance frequency recorded in the reference foreign matter detection value 1033 field is in a unit of 0.5 kHz and may have a range of 36 to 163.5 kHz.

Here, the reference quality factor may be, but is not limited to, a predefined reference operating frequency, for example, 100 kHz in a state where the corresponding wireless power receiver is placed in the charging region of the authentication wireless power transmitter while the power is turned off. It can be defined as the value of the quality factor measured corresponding to-. Specifically, the reference quality factor corresponds to the quality factor measured when the receiver is placed in the center of the charging region and the smallest value measured after moving +/- 5 mm along the X and Y axes from the center, respectively. Can be determined by the reference quality factor.

In addition, the reference resonance frequency may be defined as the resonance frequency of the transmission coil in a state where the wireless power receiver is disposed in the charging region of the authentication wireless power transmitter while the power is turned off.

At this time, the reference resonance frequency is measured in a state where no foreign matter is disposed in the charging region of the authentication wireless power transmitter. Here, the transmitter (or transmission coil) may mean a reference transmission coil.

For example, the reference transmission coil may have a coil design for authentication to establish a reference value.

The wireless power receiver according to an embodiment of the present invention may sequentially transmit a foreign matter detection status packet having two different reference foreign matter detection values at predetermined time intervals during a negotiation step according to its version.

For example, two different reference foreign matter detection values may be a reference resonance quality factor and a reference resonance frequency, as illustrated in FIG. 10A, but are not limited thereto, and two different reference foreign matters according to another embodiment may be used. The detection value may be a reference quality factor and a reference resonant frequency, as shown in FIG. 10B above.

According to an embodiment of the present disclosure, the wireless power receiver sets the mode 1032 field to binary '00' to transmit a reference resonance quality factor or a reference quality factor to the wireless power transmitter first, and then the mode 1032 field to binary '01'. It is possible to transmit the reference resonant frequency value to the wireless power transmitter by setting to ', but this is only one embodiment. In another embodiment, the reference resonant quality factor or the reference quality factor may be transmitted after the reference resonant frequency is transmitted first. have.

The wireless power transmitter may detect the foreign matter using the bandwidth calculated based on the reference foreign matter detection value included in the received foreign matter detection status packet, and the bandwidth calculated using the quality factor and the resonance frequency measured by the corresponding transmitter.

The wireless power transmitter may transmit an ACK response or a NACK response to the wireless power receiver according to the foreign matter detection result.

In addition, the wireless power transmitter may check whether the field values included in the received foreign matter detection status packet are normal, and if the received packet is not normal, the wireless power transmitter may transmit an ND response to the wireless power receiver. That is, if there is no appropriate response defined for the received packet, the wireless power transmitter may send an ND response to the wireless power receiver and ignore the contents of the received packet.

As an example when the received packet is not normal, the value of the Reserved (1601) field is not '000000', or the value of the Mode (1612) field is not '00' or '01'. There may be.

The foreign matter detection procedure according to the present embodiment may be completed before entering the power transmission step.

When at least one NACK response is received in response to a plurality of foreign object detection status packets, the wireless power receiver controls that power above a predetermined reference value is not provided to the output terminal of the wireless power receiver until power signal transmission of the wireless power transmitter is stopped. can do.

For example, the power above a predetermined reference value may be 5 Watts or more, but is not limited thereto. For example, when the NACK response is received, the wireless power receiver may not request power transmission of 5 watts or more to the wireless power transmitter until the power signal is removed.

In addition, when all of the ND responses are received in response to a plurality of foreign object detection status packets, the wireless power receiver controls not to provide power above a predetermined reference value to the output terminal of the wireless power receiver until the power signal transmission of the wireless power transmitter is stopped. can do.

If the normal foreign matter detection status packet is not normally received within a predetermined time after entering the negotiation step, the wireless power transmitter may enter the selection step after stopping the power signal transmission. In this case, if the power signal is no longer detected in the negotiation step, the wireless power receiver may release the connection with the corresponding wireless power transmitter and enter the selection step.

As another example, the wireless power receiver may transmit information about the reference resonance frequency bandwidth to the wireless power transmitter through the foreign matter detection status packet.

As shown in reference numeral 1070 of FIG. 10C, when the mode 1032 value is binary '00', the reference resonance frequency bandwidth may be recorded in the reference foreign matter detection value 1033 field.

The reference foreign matter detection value 1033 mapped to the mode 1032 value of the foreign matter detection status packet described above with reference to FIGS. 10A to 10C is only one embodiment and is a reference foreign matter mapped to another mode 1032 value according to a design. The detection value 1033 may be different.

As another example, the wireless power receiver may transmit information on the reference resonance quality factor, the reference resonance frequency, and the reference resonance frequency bandwidth to the wireless power transmitter through the foreign matter detection status packet.

As shown at 1080 in FIG. 10D, when the mode 1032 value is binary '00', a reference quality factor is recorded in the reference foreign matter detection value 1033 field, and the mode 1032 value is binary '01'. , The reference resonant frequency may be recorded in the reference foreign matter detection value 1033 field, and the reference resonant frequency bandwidth may be recorded in the foreign matter detection value 1033 field when the mode 1032 value is binary '10'.

The reference foreign matter detection value 1033 mapped to the mode 1032 value of the foreign matter detection status packet described above with reference to FIGS. 10A to 10D is only one embodiment and is a reference foreign matter mapped to another mode 1032 value according to a design. The detection value 1033 may be different.

In addition, although the foreign matter detection status packet described in FIGS. 10A to 10D is illustrated as including one reference foreign matter detection value 1033 field, the foreign matter detection status packet according to another embodiment may include a plurality of different reference foreign matters. The detection value may be defined to be transmitted in one packet.

11 is a flowchart illustrating a power transmission control method in a wireless power transmitter according to an embodiment of the present invention.

Referring to FIG. 11, in a negotiation step 440, the wireless power transmitter may receive a Foreign Object Detection (FOD) Status Packet (FOD) packet from a wireless power receiver (S1110).

As an example, as illustrated in FIG. 10A, the wireless power transmitter includes a reference resonance quality factor value 1031 and a reference resonance frequency 1032 in the message field 1030. Received foreign object detection status packet.

As another example, as illustrated in FIG. 10B, the wireless power transmitter includes a Reference Resonance Quality Factor Value (1033) and a Reference Resonance Frequency (1034) in the message field 1030. The received foreign matter detection status packet may be received.

The foreign matter detection procedure in the negotiation step 440 is based on a reference value (or a value calculated based on the reference value) received from the wireless power receiver and a measured value (or a value calculated based on the measured value) measured inside the wireless power transmitter. This is a comparison procedure, and the reference value and the measured value may be various kinds of parameters.

For example, the reference value and the measured value (or a value calculated based on the reference value and the measured value) may include, but are not limited to, a quality factor, a resonance frequency, a resonance frequency bandwidth, a resistance, an inductance, and the like.

The wireless power transmitter measures measured equivalent series resistance (Measured ESR) using a pre-stored measured peak frequency (PF_measured)-for example, a measured resonance frequency-and a measured quality factor value (Q_measured)-for example, a measured resonance quality factor value. (Equivalent Series Resistance), ESR_measured) can be calculated.

Here, ESR is a series resistance component parasitic to a capacitor or the like in an RLC series circuit. Actual capacitors and inductors used in electrical circuits are not ideal components with only capacitance or inductance. However, when connected in series with a resistor, it can be considered very close to an ideal capacitor and inductor. This resistance is defined as the equivalent series resistance (ESR).

The wireless power transmitter uses the reference peak frequency PF_reference received from the wireless power receiver, that is, the reference resonance frequency to be described later and the quality factor value corresponding to the reference peak frequency, that is, the reference resonance quality factor value to be described later. The equivalent series resistance (Reference ESR, ESR_reference) can be calculated.

The wireless power transmitter may detect the foreign matter by using the ESR_measured and the ESR_reference. As an example, the wireless power transmitter may compare the ratio of the ESR_reference and the ESR_measured with a predetermined threshold value to determine whether there is a foreign substance.

When a NACK response is received from the wireless power transmitter, the wireless power receiver may control the electronic device (or battery / load) not to be supplied with a certain intensity or more through the output terminal until the wireless power transmitter completely stops transmitting power. have. Here, the power of a certain intensity or more may be 5W as a reference, but is not limited thereto.

Hereinafter, the relationship between the ESR, the quality factor value (Q), and the frequency will be described.

The quality factor value Q in an ideal RLC serial circuit and a tuned radio frequency receiver can be calculated according to the following equation.

Here, R, L and C respectively mean storage, inductance, capacitance,

ego,

Means resonant frequency.

Because of,

Becomes

ESR is always an AC resistance measured at standard frequency, and high ESR can increase component aging, heat generation, and ripple current.

It can be calculated as

Therefore, in the above embodiment, ESR_reference is

And ESR_measured is

It can be calculated as

: Q-factor measured by wireless charger

: Peak frequency measured by the wireless charger

: Reference Q-factor in wireless charger type coil (receiver placement, no foreign substance)

: Reference peak frequency in wireless charger type coil (receiver placement, no foreign substance)

: Capacitance of resonant capacitor of wireless charger

At this time, the ratio of ESR_referenc and ESR_measured may be calculated as follows.

The wireless power transmitter according to an embodiment may determine that there is a foreign substance when the ratio of ESR_referenc and ESR_measured exceeds a predefined ratio threshold. Here, the ratio threshold value can be determined by the experimental result. For example,

If it is larger than 0.2, it can be determined that foreign matter exists.

The wireless power transmitter according to another embodiment of the present invention may determine whether a foreign substance exists by using the reference resonance bandwidth and the measured resonance bandwidth.

The definition of the resonant frequency bandwidth and the foreign material detection method based on the change of the resonant frequency bandwidth will become clearer through the description of the drawings to be described later.

In the following description, the wireless power transmitter will be described based on the embodiment in which the presence of the foreign matter based on the change in the resonance frequency bandwidth.

The wireless power transmitter may determine whether there is a foreign substance (S1120). Here, the wireless power transmitter may determine whether there is a foreign matter based on the change in the resonance frequency bandwidth.

As a result of the determination, if there is no foreign matter, the wireless power transmitter may transmit a first response signal to the corresponding wireless power receiver (S1130). Here, the first response signal may be an ACK signal.

The wireless power transmitter may perform a first power transmission control procedure after transmitting the first response signal (S1140).

As a result of the determination in step 1120, if there is a foreign substance, the wireless power transmitter may transmit a second response signal (S1150). Here, the second response signal may be a NACK signal.

The wireless power transmitter may perform a second power transmission control procedure after transmitting the second response signal (S1160).

Here, the detailed configurations of the first power transfer control procedure and the second power transfer control procedure will be more clearly understood through the following description of the drawings.

As a result of the determination, if a foreign object exists, the wireless power transmitter may transmit a second response signal (S1150). Here, the second response signal may be a NACK signal.

Referring to FIG. 12, in a negotiation step 440, the wireless power transmitter may receive a Foreign Object Detection (FOD) Status Packet (FOD) from the wireless power receiver (S1201).

As an example, as illustrated in FIG. 10A, the wireless power transmitter includes a reference resonance quality factor value 1031 and a reference resonance frequency 1032 in the message field 1030. The foreign matter detection status packet may be received, but is not limited thereto.

The wireless power transmitter may determine whether there is a foreign substance (S1202). Here, the wireless power transmitter may determine whether there is a foreign matter based on the change in the resonance frequency bandwidth.

As a result of the determination, if there is no foreign matter, the wireless power transmitter may transmit a first response signal to the corresponding wireless power receiver (S1203). Here, the first response signal may be an ACK signal.

When the first response signal is received, the wireless power transmitter may perform the first power transmission control procedure S1140.

Hereinafter, the first power transmission control procedure S1140 will be described in detail.

If the wireless power transmitter determines that there is no foreign material, the wireless power transmitter may set the guaranteed power up to the maximum or potential power.

The wireless power transmitter may transmit a transmitter power capability packet including the guaranteed power set in the negotiation step to the wireless power receiver. The wireless power receiver can determine the required power within the guaranteed power of the transmitter.

The wireless power transmitter may receive a guaranteed power packet including information about guaranteed power (or required power) required by the wireless power receiver (S1204).

The wireless power transmitter may receive a negotiation end packet from the wireless power receiver (S1205).

The wireless power transmitter may enter a calibration step 450 to perform a calibration procedure (S1206).

When the calibration procedure is completed, the wireless power transmitter may enter the power transmission step 460 and start charging (S1207).

If, as a result of the determination in step S1202, the foreign matter exists, the wireless power transmitter may transmit a second response signal in response to the foreign matter detection status packet (S1208). Here, the second response signal may be a NACK signal.

When the second response signal is received in response to the foreign substance detection status packet, the wireless power receiver may perform the second power transmission control procedure (S1160).

Hereinafter, the second power transmission control procedure S1160 will be described in detail.

The wireless power transmitter may limit the guaranteed power to the minimum guaranteed power (for example, 5W) when it is determined that the foreign matter exists.

At 5W, the wireless power transmitter may determine whether there is a foreign matter based on a threshold (or threshold) for a preset power loss, and may set a solid reference value and determine a foreign matter because the minimum power is a predetermined minimum transmission and reception period. have.

A foreign matter detection method other than foreign matter detection based on power loss may be applied.

In this case, the wireless power transmitter may control the limited guaranteed power to be transmitted to the wireless power receiver (S1209).

Here, the first power may be guaranteed power corresponding to the first power transmission mode. For example, the first power may be set to 5W, but is not limited thereto and may be set to a specific power smaller than 5W. In this case, it should be noted that the wireless power transmitter does not stop the transmission of the wireless power signal.

The wireless power transmitter may receive the guaranteed power packet (S1210). Here, the guaranteed power packet may include information about the required power determined by the wireless power receiver within the available guaranteed power of the wireless power transmitter.

When the negotiation end packet is received from the wireless power receiver, the wireless power transmitter may terminate the negotiation step 440, enter the power transmission step S460, and perform charging with a predetermined first power (S1212).

In the above-described embodiment of FIG. 12, the wireless power transmitter is described as receiving the guaranteed power packet and the negotiation termination packet during the execution of the second power transmission control procedure S1160, but this is only one embodiment. At least one of the guaranteed power packet and the negotiation end packet may not be received at the wireless power transmitter.

The wireless power transmitter according to an embodiment of the present invention may not perform the correction step 450 while performing the second power transmission control procedure S1160.

In this case, the correction step 450 may refer to a process of comparing the transmission power of the transmitter and the reception power of the receiver to accurately measure the transmission power, the reception power, and the power loss between the transmitter and the receiver.

In this case, in the second power transmission mode in which the guaranteed power is greater than 5W, the power loss may vary as the transmission power increases, and thus the power loss may be predicted in advance (calculated), and the power loss may be reflected by reflecting the value predicted in advance when the transmission power changes. Can be calculated accurately

However, in the first power transmission mode in which the guaranteed power of the minimum power is transmitted, the fixed power is set as a target and thus, there is no need to perform correction.

In addition, if at least one of the transmission power, the reception power, and the loss power is corrected in the presence of the foreign matter, the wireless power transmitter does not have the foreign matter even though the actual foreign matter exists because the correction is included because of the influence of the foreign matter. It is possible to increase the probability of not determining.

According to the present invention, the foreign matter detection accuracy may be improved by controlling the correction step 450 not to be performed while the second power transmission control procedure S1160 is performed.

Referring to FIG. 13, the wireless power transmitter may enter the power transmission step 460 when the second power transmission control procedure S1160 is completed (S1310).

The wireless power transmitter may measure (or calculate or estimate) a power loss based on a received power packet received during power transmission, that is, charging, in the power transmission step 460 (S1320).

Hereinafter, for convenience of description, the wireless power transmitter will be described as measuring power loss. However, this is only an example, and the wireless power transmitter measures the transmission power measured by the wireless power transmitter and the received power measured by the wireless power receiver. It should be noted that power loss can be calculated or estimated on the basis of this.

For example, in the power transmission step 460, the power loss may be measured based on a received power packet fed back from the wireless power receiver for a predetermined time during power transmission.

Herein, the power loss is measured based on the first received power value measured when the wireless power receiver is not connected to the battery (or load) and when the wireless power receiver is connected to the battery (or load). It may include at least one of the second power loss measured based on the measured second received power value.

As an example, the wireless power transmitter measures a power loss each time a received received power packet is received, for example a predetermined time—for example, 10 minutes—and the average value of the measured power loss (or the smallest or largest value). ) Can be confirmed as the final power loss.

As another example, the wireless power transmitter may measure power loss in response to N received power packets received continuously after entering the power transmission step 460.

The wireless power transmitter may determine whether there is a foreign substance based on the measured power loss (S1330).

For example, the wireless power transmitter may determine that a foreign substance exists when the measured power loss exceeds a predetermined power loss threshold. On the other hand, if the measured power loss is less than the predetermined power loss threshold, it may be determined that there is no foreign matter.

As another example, the wireless power transmitter may determine that there is no foreign matter when the estimated power loss corresponding to the N received power packets continuously received after entering the power transmission step is within a predetermined power loss threshold. .

It may be determined that there is no foreign matter even if it is within the threshold for a certain time, or even if the power loss after the specific time exceeds the threshold.

On the other hand, if the estimated power loss corresponding to at least one received power packet of the N received power packets continuously received after entering the power transmission step exceeds the predetermined power loss threshold, the wireless power transmitter indicates that there is a foreign substance. You can judge.

As a result of the determination, if the foreign matter exists, the wireless power transmitter may stop the power transmission and enter the selection step (S1340 and S1350).

As a result of the determination in step 1330, if there is no foreign matter, the wireless power transmitter may enter the renegotiation step and renegotiate a power transmission contract with the wireless power receiver (S1360). The guaranteed power negotiated at this time may be 5W or more.

The wireless power transmitter may reenter the power transmission step 460 according to the renegotiation result and continue charging the corresponding wireless power receiver.

For example, when no foreign matter is detected after entering the power transmission step, the wireless power transmitter may increase the strength of the transmission power to shorten the charging time by switching from the first power transmission mode to the second power transmission mode through renegotiation. Can be.

Referring to FIG. 14, the wireless power transmitter may enter the power transmission step 460 when the second power transmission control procedure S1160 is completed (S1410).

The wireless power transmitter may measure a temperature change during power transmission in the power transmission step 460 (S1420).

For example, during the power transmission step 460, the wireless power transmitter may measure the internal temperature change rate or the temperature change rate during the unit time. Here, the position where the temperature change is measured on the wireless power transmitter may be a transmission coil of the transmission antenna 640, but is not limited thereto, and other positions of the wireless power transmitter according to the design of a person skilled in the art, for example, a wireless power transmitter. The control circuit board, provided in the charging bed, may be measured.

The wireless power transmitter according to another embodiment may receive temperature information measured by the wireless power receiver at a predetermined cycle during power transmission. The wireless power transmitter may measure the temperature change based on temperature information received from the wireless power receiver.

The wireless power transmitter according to another embodiment of the present invention may determine the final temperature change based on the first temperature change measured internally and the second temperature change measured based on temperature information received from the wireless power receiver.

The wireless power transmitter may determine whether a foreign substance exists based on the measured temperature change (S1430). As an example, if the measured temperature change exceeds a predetermined temperature change threshold, the wireless power transmitter may determine that there is a foreign substance.

On the other hand, if the measured temperature change is less than the predetermined temperature change threshold, the wireless power transmitter may determine that there is no foreign matter.

As a result of the determination, if the foreign matter exists, the wireless power transmitter may stop the power transmission and enter the selection step (S1440 and S1450).

As a result of the determination in step 1430, if there is no foreign matter, the wireless power transmitter may enter the renegotiation step and renegotiate a power transmission contract with the wireless power receiver (S1360).

The wireless power transmitter may reenter the power transmission step 460 and continue charging according to the renegotiation result.

Referring to FIG. 15, the wireless power transmitter may enter the power transmission step 460 when the second power transmission control procedure S1160 is completed (S1510).

The wireless power transmitter may measure a power loss of a received power packet received during power transmission in the power transmission step 460 (S1520).

For example, in the power transmission step 460, power loss may be measured based on a received power packet fed back from the wireless power receiver during power transmission.

The wireless power transmitter may determine whether a foreign substance exists based on the measured power loss (S1530).

As a result of the determination, if there is a foreign substance, the wireless power transmitter may stop the power transmission and enter the selection step (S1540 and S1550).

As a result of the determination in step 1530, if there is no foreign matter, the wireless power transmitter may measure a temperature change during power transmission in the power transmission step 460 (S1560).

For example, during the power transmission step 460, the wireless power transmitter may measure the internal temperature change rate or the temperature change rate during the unit time.

Here, the position at which the temperature change is measured on the wireless power transmitter may be around the transmitting coil, but is not limited thereto, and may be measured at another position of the wireless power transmitter according to the design of a person skilled in the art.

The wireless power transmitter may determine whether there is a foreign substance based on the measured temperature change (S1570). As an example, if the measured temperature change exceeds a predetermined temperature change threshold, the wireless power transmitter may determine that there is a foreign substance.

As a result of the determination in step 1570, if there is no foreign matter, the wireless power transmitter may enter the renegotiation step and renegotiate a power transmission contract with the wireless power receiver (S1580). The wireless power transmitter may reenter the power transmission step 460 and continue charging according to the renegotiation result.

In the above-described embodiment of FIG. 15, the wireless power transmitter performs the foreign matter detection procedure based on the power loss and then performs the foreign matter detection procedure based on the temperature change according to the determination result. In addition, the wireless power transmitter according to another embodiment may be implemented to perform the foreign matter detection procedure based on the temperature change, and then perform the foreign matter detection procedure based on the power loss according to the determination result.

Reference numeral 1600 is a graph showing the relationship between the bandwidth and the resonant frequency in the resonant circuit of the wireless charging system.

Referring to Figure 16, the resonance frequency

It can be seen at 1612 that the amplitude of the peak-to-peak voltage or the amplitude of the voltage / current is maximum.

There may be two operating or half power bandwidth frequencies with a voltage or current that is 3 dB below the maximum amplitude. For convenience of explanation below, the two operating frequencies that are 3 dB below the maximum amplitude value 1611 are each assigned a lower bandwidth frequency (

, 1613) and upper bandwidth frequency (

1614). Here, the amplitude value below 3 dB may be about 70.7% of the maximum amplitude value 1611.

The quality factor is a parameter directly affecting the charging efficiency of the wireless power, and a 3dB drop in the quality factor may mean that the power transmission efficiency (or transmission power) is cut in half.

The resonant frequency bandwidth 1615 according to an embodiment of the present invention is a value obtained by subtracting the lower limit bandwidth frequency 1613 from the upper limit bandwidth frequency 1614.

- It can be defined as.

In the above-described embodiment of FIG. 16, the resonance frequency bandwidth 1615 is described as being determined by frequencies having a voltage or a current that is 3 dB below the maximum amplitude value 1611, but this is only one embodiment. A frequency region with a voltage or current of xdB lower than 3 dB below the maximum amplitude value 1611 may be defined as the resonant frequency bandwidth 1615. Here, it should be noted that the x value may be set differently according to the design purpose of the person skilled in the art and the characteristics of the product.

Resonant frequency bandwidth according to another embodiment of the present invention

(BW: Bandwidth) is a resonance frequency (Equation 1)

) And its resonant frequency

Quality factor values in

It may be calculated based on.

Quality Factor Values in Low Power Systems

May be expressed as Equation 2 below.

here,

Is the lower bandwidth frequency

Is the upper limit bandwidth frequency.

Referring to FIG. 17, when an object is detected in the selection step, the wireless power transmitter 1710 may measure the resonance quality factor and the resonance frequency before entering the ping step (S1701).

Here, the resonant frequency may refer to a frequency at which the voltage or current (eg, peak-to-peak voltage or peak-to-peak current) in the operating frequency band is maximum.

Alternatively, the resonant frequency may mean a frequency when the output voltage (coil voltage) is maximum with respect to the resonator input voltage.

The wireless power transmitter according to an embodiment may measure a quality factor value at a frequency interval of a predetermined unit in an operating frequency band.

The wireless power transmitter 1710 may store the measured resonance quality factor and the resonance frequency in the internal memory (S1702).

The wireless power transmitter 1710 may enter the ping phase to perform the sensing signal transmission procedure described with reference to FIG. 3 (S1703).

When the wireless power receiver 1720 is detected, the wireless power transmitter 1720 may enter an identification and configuration step to receive an identification packet and a configuration packet from the wireless power receiver 1720 (S1704 and S1705).

When the wireless power transmitter 1710 enters the negotiation step, the foreign material detection status packet may be received from the wireless power receiver 1720 (S1706).

Here, the foreign matter detection status packet may include a quality factor corresponding to a reference resonance frequency and / or a reference resonance frequency, that is, a reference resonance quality factor.

The reference resonant frequency according to the present embodiment is a resonant frequency (self-resonant frequency) of the transmission coil shifted by the coil, shield, mechanism, battery, etc. of the receiver while the wireless power receiver 1720 is disposed in the charging region of the authentication transmitter. It may mean.

For convenience of description, a quality factor value corresponding to the reference resonance frequency will be referred to as a reference resonance quality factor.

For example, the wireless power transmitter 1710 calculates a reference resonance frequency bandwidth based on a reference resonance frequency included in the foreign matter detection status packet and a quality factor at the reference resonance frequency, that is, the reference resonance quality factor, in step 1702. The resonance frequency bandwidth may be calculated based on the resonance frequency and the resonance quality factor stored in operation S1707.

As another example, the wireless power transmitter 1710 may directly receive the reference resonance frequency bandwidth through the foreign matter detection status packet.

The wireless power transmitter 1710 may determine whether there is a foreign substance based on the resonance frequency bandwidth and the reference resonance frequency bandwidth (S1708).

In general, when a foreign material is disposed in the charging region of the wireless power transmitter 1710, as described in FIG. 18 to be described later, the resonance frequency bandwidth may be rapidly increased as compared with when no foreign material is disposed.

The wireless power transmitter 1710 according to an exemplary embodiment of the present disclosure may determine that foreign matter exists in the charging region when an increase amount (or increase rate) of the resonance frequency bandwidth exceeds a predetermined threshold value (or a predetermined threshold rate).

For example, if the difference (or ratio) between the resonance frequency bandwidth and the reference resonance frequency bandwidth exceeds a predetermined threshold, the wireless power transmitter 1710 may determine that the foreign material exists in the charging region. .

On the other hand, if the difference between the resonance frequency bandwidth and the reference resonance frequency bandwidth is less than a predetermined threshold, the wireless power transmitter 1710 may determine that there is no foreign matter in the charging region.

Resonant frequency bandwidth

And reference resonance frequency bandwidth

Which is the ratio of

Can be calculated by the following equation (3).

The reference resonant frequency may refer to a resonant frequency of a transmitting coil measured in a state in which only a receiver is placed in a charging region of a transmitter (or a transmitting coil) without foreign matter.

Here, the transmitter (or transmission coil) may mean a reference transmission coil. For example, the reference transmission coil may have a coil design for authentication to establish a reference value.

The wireless power transmitter 1710 may generate a predetermined response packet according to the determination result of the presence of the foreign matter and transmit it to the wireless power receiver 1720.

For example, if it is determined in step 1708 that the foreign material exists, the wireless power transmitter 1710 may generate a NACK response packet and transmit it to the wireless power receiver 1720. On the other hand, if it is determined that there is no foreign matter, the wireless power transmitter 1710 may generate an ACK response packet and transmit the generated ACK response packet to the wireless power receiver 1720.

In addition, in operation 1708, when it is impossible to determine whether a foreign substance exists, the wireless power transmitter 1710 may generate a Not Defined (ND) response packet and transmit the generated Notifyd (ND) response packet to the wireless power receiver 1720.

When the wireless power receiver 1720 receives a NACK response or an ND response from the wireless power transmitter 1710, the electronic device (or battery) through its output terminal until power transmission by the wireless power transmitter 1710 is completely stopped. / Load) can be controlled to not supply more than a certain intensity of power.

Here, the power of a certain intensity or more may be 5W as a reference, but is not limited thereto, and may vary depending on a design and an electronic device equipped with the wireless power receiver 1720 and / or a battery / load connected to the wireless power receiver 1720. Can be defined.

In the above-described embodiment of FIG. 17, the wireless power transmitter 1710 receives a foreign matter detection status packet including a quality factor value at the reference resonance frequency and the reference resonance frequency, that is, the reference resonance quality factor value, and the reference resonance frequency. And a reference resonance frequency bandwidth based on the reference resonance quality factor value.

The reference resonant frequency may refer to a resonant frequency of a transmitting coil measured in a state where only a receiver is mounted on a transmitter (or a transmitting coil) without foreign matter.

The wireless power transmitter 1710 according to another embodiment may receive a foreign matter detection status packet including a reference resonance frequency and / or a reference quality factor value, and calculate a reference resonance frequency bandwidth based on the reference resonance frequency and the reference quality factor. It may be.

Here, the reference quality factor may be a quality factor in the reference transmitter coil for authentication corresponding to a predefined reference operating frequency. As an example, the measurement frequency may be 100 KHz.

According to another exemplary embodiment, the wireless power transmitter 1710 may receive a foreign matter detection status packet including a reference resonance frequency bandwidth, and determine whether a foreign material exists based on the resonance frequency bandwidth and the reference resonance frequency bandwidth.

The wireless power transmitter 1710 according to another embodiment may receive the reference resonance quality factor, the reference resonance frequency, and the reference resonance frequency bandwidth through at least one foreign matter detection status packet to determine whether there is a foreign matter.

Referring to FIG. 18, reference numeral 1810 is a graph showing a resonator amplification ratio (Vin / Vout) pattern in an operating frequency band when no foreign material is disposed between the receiver and the charging region, and reference numeral 1820 is a diagram between the receiver and the charging region. Is a graph showing the resonator amplification ratio (Vin / Vout) pattern in the operating frequency band when foreign matter is present.

In an embodiment of the present invention, the resonance quality factor is defined as the resonator amplification ratio Vin / Vout at the resonant frequency, and the resonant frequency may mean a frequency at which the resonant amplification ratio is maximum.

In another embodiment, the resonance quality factor may be defined as a resonator peak to peak voltage, and the resonant frequency may mean a frequency at which the resonator peak to peak voltage is maximum.

Reference numeral 1811 denotes a resonance frequency bandwidth when no foreign matter is disposed in the charging region, and reference numeral 1821 shows a resonance frequency bandwidth when foreign matter is disposed in the charging region.

Here, the frequency bandwidth when no foreign matter is disposed in the charging region is the reference resonance frequency bandwidth described with reference to FIG. 17.

The frequency bandwidth when the foreign matter is disposed in the charging region corresponds to the resonance frequency bandwidth described with reference to FIG.

May correspond to.

As shown in FIG. 18, when the foreign matter is disposed in the charging region, it can be seen that the resonance frequency bandwidth increases. That is, the reference resonance frequency bandwidth

Resonant Frequency Bandwidth (1811)

(1821) becomes large.

In addition, when the foreign matter is disposed in the charging region, as shown in reference numeral 1830, the resonant frequency having the maximum quality factor may move to the right. That is, the resonant frequency 1832 when the receiver and the foreign matter are disposed in the charging region increases compared to the resonant frequency 1831 before the foreign matter is disposed in the charging region (when there is only a receiver). Alternatively, the resonance frequency may increase as the influence of the shielding agent decreases even when the distance between the receiver and the charging region increases.

The wireless power transmitter according to an embodiment of the present invention may determine that foreign matter exists in the charging region when the increase amount (or increase rate) of the resonance frequency bandwidth exceeds a predetermined threshold value (or a predetermined threshold ratio).

For example, resonant frequency bandwidth

And reference resonance frequency bandwidth

When the difference value of S exceeds a predetermined threshold, the wireless power transmitter may determine that foreign matter exists in the charging region. On the other hand, resonant frequency bandwidth

And reference resonance frequency bandwidth

If the difference is less than or equal to a predetermined threshold, the wireless power transmitter may determine that no foreign matter exists in the charging region.

As another example, the reference resonance frequency bandwidth

Resonant Frequency Bandwidth at

If the rate of change exceeds a predetermined threshold rate, the wireless power transmitter may determine that the foreign matter exists in the charging region. In contrast, the reference resonant frequency bandwidth

Resonant Frequency Bandwidth at

If the rate of change of the furnace is less than or equal to a predetermined threshold ratio, the wireless power transmitter 1710 may determine that there is no foreign matter in the charging region.

As another example, the wireless power transmitter may determine whether a foreign substance is present based on the movement of the resonance frequency having the maximum quality factor.

For example, referring to FIG. 18, when the increase amount (or increase rate) of the resonance frequency 1822 to the reference resonant frequency 1821 is greater than or equal to a predetermined threshold (or threshold ratio), the wireless power transmitter is configured to place foreign matter in the charging region. It can be judged that.

However, in the case of a foreign material of a specific material, for example, a foreign material of iron (IRON), the permeability is very high, which has a very small influence on the inductance of the transmission coil. Therefore, there is a problem that it is difficult to distinguish the presence or absence of the foreign matter by comparing the magnitude of the resonance frequency shift according to the foreign matter arrangement.

In addition, the quality factor may not be divided into foreign matters because of the difference in resistance components for aluminum-based foreign matters.

Using the resonant frequency and the quality factor together to compare the bandwidth as a unified criterion has the advantage of utilizing two complementary variables.

The wireless power transmitter according to another embodiment of the present invention may control to perform a foreign matter detection procedure based on the change of the resonance frequency bandwidth according to the foreign matter detection result based on the resonance frequency shift.

For example, if the measured resonant frequency change amount (or change rate) is greater than or equal to a predetermined threshold (or threshold rate), the wireless power transmitter does not perform a foreign matter detection procedure based on the change of the resonant frequency bandwidth and the foreign matter exists in the charging region. You can judge that.

On the other hand, if the measured resonance frequency change amount (or change ratio) is less than a predetermined threshold (or threshold ratio), the wireless power transmitter may determine whether a foreign material exists by performing a foreign material detection procedure based on the resonance frequency bandwidth change.

The foreign material detection method based on the conventional quality factor described in FIG. 5 has a problem in that reliability of foreign material detection is poor due to some of the following problems.

First, in the case of the quality factor, the value varies greatly according to the configuration aspect and type of the wireless charging device, and in the case of some smartphones equipped with a wireless power receiver, other configurations of the smartphone (for example, friendly metal) Due to this, the quality factor value may be too small even if no foreign matter is placed. If the quality factor is small, the difference in quality factor values according to the presence or absence of foreign matters is small, thereby increasing the probability of misjudgment.

This misjudgment can not only be a direct cause of heat generation, but can also cause device damage. Or even though there is no foreign matter, it may cause a problem that the charging is not started by determining the smart phone as the foreign matter.

Second, in the case of the quality factor, there is a problem that the amount of change in the quality factor value measured before and after the placement of the foreign matter according to the kind of foreign matter is very small.

If a foreign material having a small change in the quality factor is disposed, the wireless power transmitter may determine that the foreign material does not exist even though the foreign material is disposed in the charging region. These misjudgments can not only be a direct cause of heat generation, but can also lead to equipment breakdown and power loss.

Third, in the case of the quality factor, depending on the type of the receiving coil mounted in the wireless power receiver, some of the wireless power receiver may have a large change in the quality factor before and after placement in the charging area even though there is no foreign matter.

In this case, the wireless power transmitter may misjudge that the foreign matter is disposed even though the foreign matter is not disposed in the actual charging region. This may cause inconvenience to the user since charging stops.

Hereinafter, the amount of change in the quality factor value when foreign matter is placed in the charging region of the wireless power transmitter

Variation in Bandwidth of Resonant Frequency

Which of the following is greater?

Amount of change of quality factor value

Variation in Bandwidth of Resonant Frequency

The difference value of may be expressed by Equation 4 below.

here,

Is the measurement quality factor value,

Is the reference quality factor value.

Is the measured resonant frequency,

Is the reference resonance frequency.

If foreign matter exists in the charging area,

ego,

Becomes

if,

Is 1, i.e., there is no resonant frequency shift depending on the placement of foreign objects.

end

This,

Equation 4 is

It can be expressed as.

here,

this

Assuming less than

Equation 4 is

Become,

Because of,

Becomes

Therefore, the amount of change in resonance frequency bandwidth

The amount of change in the quality factor

Can be greater than

if,

Is assumed to be greater than 1, i.e., there is a resonant frequency shift depending on the foreign material placement.

end

It can be expressed as.

Hereinafter, the resonant frequency bandwidth when there is no resonant frequency shift according to the foreign matter arrangement

, The resonant frequency bandwidth when the resonant frequency shift is

Assume

In this case, the amount of change in the resonance frequency bandwidth according to the foreign matter arrangement may be expressed as shown in Equation 5 below.

At this time,

this

If less than

Equation 5 is

This becomes

Is always

Greater than

In summary, when the foreign matter is disposed in the charging region, the amount of change in the resonance frequency bandwidth

The amount of change in the quality factor

You can see that it is larger.

In the above Equation 5, if the foreign matter is not disposed in the charging region,

and

Is the same,

and

The same applies to. Therefore, the amount of change in resonance frequency bandwidth

The amount of change in the quality factor

Are the same.

Looking at the above, it can be seen that when there is no foreign matter, BW and Q is the same amount of change, when there is a foreign matter, BW is always larger than the change of Q. This means that it is easier for the BW to judge the presence of foreign substances when determining the presence of foreign substances.

Referring to FIG. 19, the wireless power transmission apparatus 1900 may include an antenna 1910, a power converter 1920, a modulator 1930, a memory 1950, and a controller 1960.

When the antenna 1910 receives an AC power signal from the power converter 1920, the antenna 1910 may wirelessly output through the provided resonant circuit.

The power converter 1920 may convert a power signal applied from an external power source into an AC power signal of a specific frequency.

Here, the frequency of the AC power signal may be selected and controlled by the controller 1960 within a predefined operating frequency band.

The modulator 1930 may demodulate a signal received through the antenna 1910 and transmit the demodulated signal to the controller 1960. As an example, the modulator 1930 may demodulate and transmit the amplitude modulated signal, that is, the in-band signal, sensed through the antenna 1910 to the controller 1960.

In addition, the modulator 1930 may transmit the signal generated by the controller 1960 to the antenna 1910 by modulating, for example, but not limited to, amplitude modulation.

In the description of FIG. 19, the demodulator 1930 modulates or demodulates an in-band communication signal. However, this is only one embodiment, and the demodulator 1930 according to another embodiment performs short-range wireless communication. It can also process the signal transmitted and received. To this end, the antenna 1910 may be further provided with a communication antenna for short-range wireless communication as well as a charging antenna for wireless power transmission.

When the demodulator 1930 enters the negotiation step, the demodulator 1930 may demodulate and transmit the foreign matter detection status packet to the controller 1960.

For example, the wireless power transmitter may refer to a reference resonance quality factor (or reference quality factor and / or reference resonance) as illustrated in FIGS. 10A to 10B through the foreign matter detection state packet. Reference Resonance Frequency may be received.

As another example, the wireless power transmitter may receive the reference resonance frequency bandwidth as illustrated in FIG. 10C through the foreign matter detection status packet.

As another example, the wireless power transmitter may transmit a reference resonance quality factor (or reference quality factor and / or reference resonance frequency and reference resonance frequency) through a foreign matter detection state packet. It may also receive bandwidth.

The controller 1960 can measure the quality factor value.

When the controller 1960 detects an object disposed in the charging area, the controller 1960 may measure a quality factor value before entering the ping step. In this case, the controller 1960 may control the quality factor in a predetermined frequency unit in the operating frequency band.

The controller 1960 may determine the resonance frequency using the amplitude of the peak voltage across the transmitting coil.

The controller 1960 may calculate the resonance frequency bandwidth based on the measured resonance frequency and the resonance quality factor.

In addition, the controller 1960 may calculate the reference resonance frequency bandwidth based on the reference resonance frequency and the reference resonance quality factor.

The controller 1960 may calculate the change amount (or change rate) of the resonance frequency bandwidth.

The change amount of the resonance frequency bandwidth may be calculated by subtracting the reference resonance frequency bandwidth from the resonance frequency bandwidth.

The change rate of the resonance frequency bandwidth may be calculated by subtracting the reference resonance frequency bandwidth from the resonance frequency bandwidth and dividing by the reference resonance frequency bandwidth.

Here, the method for calculating the resonance frequency bandwidth and the change ratio of the resonance frequency bandwidth is replaced with the description of the above drawings.

The controller 1960 may compare the calculated resonance frequency bandwidth change amount (or change rate) with a predetermined threshold value (or threshold rate) to determine whether there is a foreign substance.

As an example, if the calculated resonance frequency bandwidth change amount (or change rate) exceeds a predetermined threshold value (or threshold rate), the controller 1960 may determine that foreign matter exists in the charging region.

On the other hand, if the calculated resonance frequency bandwidth change amount (or change ratio) is smaller than the predetermined threshold value (or threshold ratio), the controller 1960 may determine that there is no foreign matter in the charging region.

The threshold value (or threshold ratio) compared with the resonant frequency bandwidth change amount (or change rate) may be a fixed value regardless of the type of the wireless power transmission apparatus, but this is only one embodiment, and the threshold value according to another embodiment (Or the threshold ratio) may be set differently according to the type of wireless power transmitter and / or the type of wireless power receiver identified.

As another example, the controller 1960 may determine the threshold value based on the reference resonance frequency bandwidth. This threshold is a unified threshold that allows you to compare quality factors and resonant frequencies all at once. The controller 1960 may compare the unified threshold and the measured resonance frequency bandwidth to determine whether there is a foreign substance.

The controller 1960 may generate a predetermined response signal according to the foreign matter detection result, and transmit the generated response signal to the corresponding wireless power receiver through the modulator 1930.

For example, the controller 1960 may generate an ACK response signal when a foreign material is detected, and generate a NACK response signal when the foreign material is not detected.

The operation of the controller 1960 after the response signal is replaced by the description of the above-described drawings.

The memory 1950 may record a program and various register values necessary for the operation of the wireless power transmitter 1900.

When the wireless power transmitter 1900 is booted, the controller 1950 may load a program stored in the memory 1950 to control the operation and input / output of the wireless power transmitter 1900.

In addition, information about a measured quality factor value, a measured resonance frequency, a measured resonance frequency bandwidth, and the like may be recorded in the memory 1950.

Referring to FIG. 20, reference numeral 2010 shows a change pattern of quality factor values measured for various foreign substances by transmitter type, and reference numeral 2020 shows a change pattern of resonance frequency bandwidth measured for various foreign substances by transmitter type. .

In detail, the results of this experiment show that four different foreign materials, namely FO # 1, in three different transmitters having different types of transmission coils, that is, the first to third transmitters (2011, 2012, 2013), The change pattern of the quality factor values and the change pattern of the resonance frequency bandwidth are measured for FO # 2, FO # 3, and FO # 4-.

Referring to reference numeral 2010, when the foreign matter is placed in the filling region, the quality factor value is lowered for all the foreign matter.

In addition, reference numeral 2010 shows that the ratio of the quality factor value is lowered according to the type of the foreign matter and the type of the transmitter.

In particular, reference numeral 2010 shows that the drop rate of the quality factor value is the lowest when FO # 4 is placed on the first transmitter 2011.

Referring to reference numeral 2020, when a foreign material is disposed in the charging region, the resonance frequency bandwidth is increased regardless of the type of the transmitter and the type of the foreign material.

Further, reference numeral 2020 shows that the rate at which the resonance frequency bandwidth increases is different according to the type of the transmitter and the type of the foreign matter.

In particular, reference numeral 2010 shows the lowest increase rate of the resonance frequency bandwidth when FO # 4 is disposed on the first transmitter 2011.

When comparing the rate of change of the quality factor value and the rate of change of the resonance frequency bandwidth according to the type of foreign matter disposed in the charging region for each transmitter type, it can be seen that the rate of change of the resonance frequency bandwidth is relatively larger than the rate of change of the quality factor value. have.

In particular, when FO # 4 is disposed in the charging region of the first transmitter 2011, the rate of change of the quality factor value is very low, which may increase the probability that the transmitter fails to detect the foreign matter.

Referring to the

drawing numbers

2010 and 2020, the minimum quality factor change ratio

Minimum Resonance Frequency Bandwidth Change Rate (2014)

It can be seen that 2021 is more than twice as large.

Therefore, the foreign matter detection method based on the resonant frequency bandwidth according to the present invention has the advantage that it can detect the foreign matter more accurately than the foreign matter detection method based on the conventional quality factor value.

Referring to FIG. 21, reference numeral 2110 shows a pattern of change of quality factor values measured for various foreign matters by receiver type, and reference numeral 2120 shows a pattern of change of resonance frequency bandwidth measured for various foreign matters by receiver type. .

Specifically, the results of this experiment show that five different receivers of different types in the charging region of a particular transmitter—ie, first to fifth receivers—and four different foreign objects—that is, FO # 1, FO # 2, FO #. 3, shows the pattern of change in the quality factor value and the pattern of change in the resonant frequency bandwidth measured when FO # 4- is placed.

Referring to reference number 2110, when a foreign material is disposed in the charging region, the quality factor value is lowered regardless of the type of the receiver and the type of the foreign material.

In addition, reference numeral 2110 shows that the ratio of the quality factor value is lowered according to the type of the foreign matter and the type of the receiver.

In particular, reference numeral 2110 shows that the drop ratio of the quality factor value is lowest when the first receiver and the FO # 4 are disposed in the charging region of the transmitter.

Referring to reference number 2120, when a foreign material is disposed in the charging region, the resonance frequency bandwidth is increased regardless of the type of the receiver and the type of the foreign material.

In addition, reference numeral 2120 shows that the rate of increase in the resonant frequency bandwidth varies according to the type of receiver and the type of foreign matter disposed in the charging region.

In particular, reference number 2120 shows the lowest increase rate of the resonance frequency bandwidth when the first receiver and the FO # 4 are disposed in the charging region.

Comparing the rate of change of the quality factor value and the rate of change of the resonance frequency bandwidth according to the type of the receiver and the type of the foreign matter disposed in the charging region, it can be seen that the rate of change of the resonance frequency bandwidth is larger than the rate of change of the quality factor value. Can be.

In particular, when the first receiver having the Q value of 35 and the FO # 4 are disposed in the charging region, the rate of change of the quality factor value is very low, which may increase the probability that the transmitter fails to detect the foreign matter.

Referring to

reference numbers

2110 and 2120, the minimum quality factor change ratio

Rate of change of minimum resonant frequency bandwidth than (2111)

It can be seen that 2121 is more than twice as large.

In addition, the wireless power transmission apparatus according to the present invention has the advantage of being able to block the heat generation and power loss due to the foreign matter in advance, as well as to prevent damage to the device due to heat generation by detecting the foreign matter more accurately.

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

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

The present invention relates to wireless charging, and in particular, can be applied to a wireless power transmitter equipped with a foreign material detection function.

Claims

Measuring a resonance quality factor and a resonance frequency;

Receiving a foreign matter detection status packet comprising a reference resonance quality factor and a reference resonance frequency;

Calculating a resonance frequency bandwidth based on the resonance quality factor and the resonance frequency;

Calculating a reference resonance frequency bandwidth based on the reference resonance quality factor and the reference resonance frequency; And

Determining the presence or absence of the foreign matter based on the resonance frequency bandwidth and the reference resonance frequency bandwidth

Wireless power transmission method comprising a.
Measuring a resonance quality factor and a resonance frequency;

Receiving a foreign matter detection status packet including a reference resonance frequency bandwidth;

Calculating a resonance frequency bandwidth based on the resonance quality factor and the resonance frequency;

Determining the presence or absence of the foreign matter based on the resonance frequency bandwidth and the reference resonance frequency bandwidth

Wireless power transmission method comprising a.
Measuring a resonance quality factor and a resonance frequency;

Receiving a foreign matter detection status packet comprising a reference resonance quality factor, a reference resonance frequency and a reference resonance frequency bandwidth;

Calculating a resonance frequency bandwidth based on the resonance quality factor and the resonance frequency;

Determining a reference resonance frequency bandwidth based on at least one of the reference resonance quality factor, a reference resonance frequency, and a reference resonance frequency bandwidth; And

Determining the presence or absence of the foreign matter based on the resonance frequency bandwidth and the reference resonance frequency bandwidth

Wireless power transmission method comprising a.
The method according to any one of claims 1 to 3,

And the resonance frequency is a frequency at which the resonator amplification ratio is maximum, and the resonance quality factor is calculated based on the resonator amplification ratio to the resonance frequency.
The method according to any one of claims 1 to 3,

The resonance frequency is a frequency at which the peak-to-peak voltage of the resonator is maximum, and the resonance quality factor is calculated based on the peak-to-peak voltage at the resonance frequency.
The method according to any one of claims 1 to 3,

Determining whether a foreign matter is present based on the resonance frequency bandwidth and the reference resonance frequency bandwidth,

Determining the presence of foreign matter by comparing the variation ratio of the resonance frequency bandwidth with the threshold ratio

Wireless power transmission method comprising a.
The method of claim 6,

The variation ratio of the resonance frequency bandwidth is calculated by dividing the value obtained by subtracting the reference resonance frequency bandwidth from the resonance frequency bandwidth by the reference resonance frequency bandwidth.
The method of claim 7, wherein

And the threshold ratio is set to any one of a value greater than 25% and less than 35%.
The method of claim 6,

Determining whether the foreign material is present by comparing the variation ratio of the resonance frequency bandwidth with a threshold ratio,

When the variation ratio of the resonance frequency bandwidth exceeds the threshold ratio, determining that there is a foreign substance and transmitting a NACK response; And

If the rate of change of the resonant frequency bandwidth is less than the threshold rate, determining that there is no foreign material and transmitting an ACK response

Wireless power transmission method comprising a.