KR102572975B1 - Wireless power transmission method and apparatus - Google Patents

Abstract

The present invention relates to a wireless power transmission method and apparatus therefor, and the wireless power transmission method according to an embodiment of the present invention includes measuring a resonance quality factor and a resonance frequency; Receiving a foreign matter detection status packet including 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 exists based on the resonance frequency bandwidth and the reference resonance 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 capable of detecting foreign substances during wireless charging and an apparatus therefor.

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

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

In addition, when the wireless power transmitter erroneously determines that a foreign substance exists in the charging area even though FO does not actually exist in the charging area, charging may be stopped.

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

The present invention was conceived to solve the problems of the prior art described above, 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 more accurately detecting foreign matter.

Another object of the present invention is to provide a wireless power transmission method and apparatus for preventing unnecessary charging interruption in advance by minimizing foreign matter detection errors.

Another object of the present invention is to provide a wireless power transmitter capable of preventing device damage caused by foreign substances and enabling seamless charging through adaptive transmission power control according to the presence or absence of foreign substances.

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

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

A wireless power transmission method according to an embodiment of the present invention includes measuring a resonance quality factor and a resonance frequency; Receiving a foreign matter detection status packet including 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 exists based on the resonance frequency bandwidth and the reference resonance frequency bandwidth.

A wireless power transmission method according to another embodiment of the present invention includes measuring a resonance quality factor and a resonance frequency; Receiving a foreign matter detection status packet including a reference resonant frequency bandwidth; calculating a resonance frequency bandwidth based on the resonance quality factor and the resonance frequency; and determining whether a foreign substance exists based on the resonance frequency bandwidth and the reference resonance frequency bandwidth.

A wireless power transmission method according to another embodiment of the present invention includes measuring a resonance quality factor and a resonance frequency; Receiving a foreign matter detection status packet including 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, the reference resonance frequency, and the reference resonance frequency bandwidth; and determining whether a foreign substance exists based on the resonance frequency bandwidth and the reference resonance frequency bandwidth.

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

Also, 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.

In addition, the step of determining whether a foreign substance exists based on the resonance frequency bandwidth and the reference resonance frequency bandwidth,

The method may include determining whether or not a foreign substance is present by comparing a variation ratio of the resonance frequency bandwidth with a threshold ratio.

Also, the variation 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 critical ratio may be set to any one of values greater than 25% and less than 35%.

In addition, the step of comparing the variation ratio of the resonant frequency bandwidth with a threshold ratio to determine whether a foreign substance exists is determined that a foreign material exists when the variation ratio of the resonance frequency bandwidth exceeds the threshold ratio, and a NACK response is generated. transmitting; and determining that no foreign matter exists and transmitting an ACK response when the variation rate of the resonant frequency bandwidth is smaller than the threshold rate.

Another embodiment of the present invention may provide a computer readable recording medium on which a program for executing any one of the wireless power transmission control methods is recorded.

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

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

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

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

In addition, the present invention has the advantage of providing a wireless power transmission method and apparatus in which unnecessary charging interruption is prevented in advance by minimizing foreign matter detection errors.

In addition, the present invention has the advantage of providing a wireless power transmitter capable of preventing device damage caused by foreign substances and enabling seamless charging through adaptive transmission power control according to the presence or absence of foreign substances.

In addition, the present invention has the advantage of providing a wireless power transmitter capable of stably transmitting wireless power over a wide range according to the type of receiver and the power transmission environment.

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

1 is a block diagram for explaining a wireless charging system according to an embodiment of the present invention.
2 is a block diagram for explaining a wireless charging system according to another embodiment of the present invention.
3 is a diagram for explaining a detection signal transmission procedure in a wireless charging system according to an embodiment of the present invention.
4 is a state transition diagram for explaining a wireless power transmission procedure according to an embodiment of the present invention.
5 is a flowchart for explaining a foreign matter detection procedure in a wireless power transmission system according to an embodiment of the present invention.
6 is a block diagram for explaining the structure of a wireless power transmission device according to an embodiment of the present invention.
FIG. 7 is a diagram for explaining the transmission antenna configuration of FIG. 6 according to an embodiment of the present invention.
8 is a block diagram for explaining the structure of a wireless power receiver interworking with the wireless power transmitter of FIG. 6 according to an embodiment of the present invention.
9 is a diagram for explaining a power transmission control method according to whether or not a foreign substance is detected in a wireless power transmitter according to the prior art.
10A to 10D are diagrams for explaining 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 explaining a wireless power transmission method in a wireless power transmitter according to another embodiment of the present invention.
14 is a diagram 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 explaining a wireless power transmission method in a wireless power transmitter according to another embodiment of the present invention.
16 is a diagram for explaining a resonance frequency bandwidth according to an embodiment of the present invention.
17 is a flowchart for explaining a foreign matter detection procedure using a resonance frequency bandwidth in a wireless power transmission system according to an embodiment of the present invention.
18 is a diagram for explaining a change pattern of a resonant frequency bandwidth according to whether a foreign material is disposed.
19 is a diagram for explaining the structure of a wireless power transmission device according to an embodiment of the present invention.
20 shows foreign material detection test results for various foreign materials for each transmitter type.
21 shows foreign material detection test results for various foreign materials for each receiver type.

BEST MODE FOR CARRYING OUT THE INVENTION

A wireless power transmission method according to an embodiment of the present invention includes measuring a resonance quality factor and a resonance frequency; Receiving a foreign matter detection status packet including 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 exists based on the resonance frequency bandwidth and the reference resonance frequency bandwidth.

Mode for Carrying Out the Invention

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

In 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, memories, sensors, etc.), This is just one embodiment, and some or all of the functions of the component may be implemented as software.

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

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

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

The transmitter according to the present invention may be configured in a pad type, a cradle type, an access point (AP) type, a small base station type, a stand type, a ceiling buried type, a wall hanging type, etc. Power can also be transmitted. To this end, the transmitter may include at least one wireless power transmission unit.

Here, the wireless power transmission unit generates a magnetic field in the coil of the power transmitter and uses the principle of electromagnetic induction in which electricity is induced in the coil of the receiver under the influence of the magnetic field, and various wireless power transmission standards based on the electromagnetic induction method may be used.

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

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

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

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

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

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

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 modulated signal. (42) may be transmitted to the wireless power transmitter 10.

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

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

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

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

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

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

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

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

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

When it is confirmed that the connected wireless power transmitter 10 supports the fast charging mode, the wireless power receiver 20 may inform the electronic device 30 of this.

The electronic device 30 may display that high-speed charging is possible through a predetermined display unit provided therein, which may be, for example, a liquid crystal display.

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

For example, as shown at reference numeral 200a, the wireless power receiver 20 may be composed of a plurality of wireless power receivers, and a plurality of wireless power receivers are connected to one wireless power transmitter 10 to provide wireless Charging can also be performed.

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

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

As another example, as shown in reference numeral 200b, the wireless power transmitter 10 may be composed of a plurality of wireless power transmitters.

In this case, the wireless power receiver 20 may be simultaneously connected to a plurality of wireless power transmitters, and may simultaneously receive power from the connected wireless power transmitters and perform charging.

At this time, the number of wireless power transmitters connected to the wireless power receiver 20 is adaptively based on the amount of power required by the wireless power receiver 20, the state of charge of the battery, the power consumption of the electronic device, and the amount of available power of the wireless power transmitter. can be determined

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

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

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

Subsequently, the wireless power transmitter sequentially transmits the detection signal 127 through the secondary detection signal transmission procedure shown in reference numeral 120, and transmits power among the transmission coils 111 and 112 having received the signal strength indicator 126. Efficiency (or charging efficiency) - that is, the alignment between the transmitting coil and the receiving coil - is identified, and power is transmitted through the identified transmitting coil - that is, wireless charging is performed - can be controlled. .

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

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

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

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

The selection step 410 is a step that is transitioned to - including, for example, reference numerals S402, S404, S408, S410 and S412 - if a specific error or specific event is detected while power transmission is initiated or maintained. can

Here, specific errors and specific events will become clear through the following description.

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

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

For example, in the selection step 410, the transmitter transmits an analog ping signal of very short pulses, and based on the current change of the transmitting coil (or primary coil), the active area of the interface surface ( It can detect whether an object exists in the Active Area). Here, the active area may mean an area where a receiver is disposed and wireless charging is possible.

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

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

When the object is detected in the selection step 410, the wireless power transmitter corresponds to the provided LC resonant circuit - for example, the LC resonant circuit may include a coil (inductor) and a resonant capacitor connected in series. quality factors 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 in the charging area together with foreign substances.

Here, the quality factor value may be measured prior to entering the ping step 420 . Also, the quality factor value may be measured in a state in which power transmission through the transmission coil is temporarily suspended.

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 unit time in the time domain.

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

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

A 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.

A wireless power transmitter according to another embodiment may measure a quality factor value in units of a predetermined frequency within an operating frequency band usable for wireless power transmission.

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

Hereinafter, for convenience of explanation, the frequency at which the quality factor value is maximum within the operating frequency band is referred to as a quality factor peak frequency or simply a peak frequency or a resonance frequency for convenience of explanation.

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

In particular, the quality factor value measured using the transmitter used to authenticate the receiver for the same operating frequency - referred to as 'authentication transmitter' for convenience of explanation below - and the LCR meter is the quality factor value measured in the commercial transmitter. may differ 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 procedures are normally completed, the wireless power transmitter may enter the negotiation phase (440) (S405).

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

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

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

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

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

Here, the reference quality factor value means a quality factor value at a reference operating frequency measured in a state in which foreign substances are not placed in the charging area of the authentication transmitter.

By comparing the reference quality factor value received in the negotiation step 440 and the quality factor value corresponding to the reference operating frequency measured before the ping step 420—hereinafter referred to as the current quality factor value for convenience of description— existence can be determined.

However, a transmitter whose reference quality factor value is measured—that is, a transmitter for authentication—and a transmitter whose current quality factor value is measured may be different from each other. Therefore, the determined threshold value of the quality factor for determining whether a foreign material is present 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 value based on the received reference quality factor value.

Inductance and/or a series resistance component in the transmission coil may be reduced according to a change in the surrounding environment of the transmission coil, and as a result, a resonant frequency of the transmission coil may be changed (shifted). That is, the quality factor peak frequency, which is the frequency at which the maximum quality factor value is measured within the operating frequency band, may be shifted.

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

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

is calculated as

When only the wireless power receiver is disposed in the charging area of the transmitter, the resonant frequency decreases because the L value increases. That is, the resonant frequency moves (shifts) to the left on the frequency axis.

On the other hand, if a foreign substance is placed in the charging area of the transmitter, the L value is reduced, so the resonant frequency increases. That is, the resonant frequency moves (shifts) to the right on the frequency axis.

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

The transmitter is referred to as a 'reference quality factor peak frequency (pf_reference)', 'reference peak frequency' or 'reference resonance frequency' for convenience of explanation, below the pre-set quality factor peak frequency corresponding to the corresponding transmitter type. Business card-related information can be obtained from the receiver or held in a predetermined recording area in advance.

When detecting that an object is placed in the charging area, the transmitter may measure a quality factor value within an operating frequency band before entering the ping step 420 and identify a 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 'measured quality factor peak frequency (pf_measured)', 'measured peak frequency' or 'measured resonance frequency'.

In the negotiation step 430, the transmitter may determine whether or not a foreign substance is present based on the reference quality factor peak frequency and the measured quality factor peak frequency.

If information on 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 identification and configuration step 430 may transmit information about the transmitter type of the transmitter to the receiver.

The receiver may read a pre-stored reference quality factor peak frequency corresponding to the received transmitter type information from a corresponding memory, 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 material exists by using both a foreign material detection method based on a quality factor peak frequency and a foreign material detection method based on a quality factor value.

For example, when there is no significant difference as a result of comparing the reference quality factor value corresponding to the transmitter type and the measured quality factor value - for example, when the difference between the two values is 10% or less -, the reference quality corresponding to the transmitter type The presence or absence of a foreign material 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 a foreign material is present.

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

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

Thereafter, when information on the reference quality factor peak frequency is received from the receiver, the transmitter may determine whether or not the foreign material 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 area.

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

In the ping step 420, if the transmitter does not receive a digital ping response signal (for example, a signal strength packet) from the receiver, it may proceed to the selection step 410 again.

In addition, in the ping step 420, when the transmitter receives a signal indicating that power transmission has been completed—that is, a charge completion packet—from the receiver, the transmitter may proceed to the selection step 410.

Upon completion of the ping phase 420, the transmitter may transition to an identification and configuration phase 430 to identify the receiver and collect receiver configuration and status information.

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

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

In addition, in the identification and configuration step 430, the transmitter determines whether an unwanted packet is received (unexpected packet), a desired packet is not received for a predefined period of time (time out), there is a packet transmission error (transmission error), or power If no power transfer contract is established (no power transfer contract), the process may proceed to the selection step 410 .

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

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

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

In the identification and configuration step 430, the wireless power transmitter according to an embodiment does not perform the negotiation step 440 when the corresponding wireless power receiver is identified as a receiver supporting only the first power transmission mode, and directly transmits the power. (460).

After entering the power transmission step 460, the wireless power transmitter may periodically perform a foreign object detection procedure.

Here, the foreign material detection procedure may be a foreign material detection procedure based on a quality factor value, but is not limited thereto, and a foreign material detection procedure based on power loss may be applied.

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

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

As another example, in the negotiation step 440, the transmitter may receive a status packet including a reference quality factor value and a reference peak frequency value corresponding to the transmitter type.

In this case, the transmitter may determine a quality factor threshold value for foreign matter detection based on a reference quality factor value corresponding to the transmitter type.

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

The transmitter sets the determined quality factor threshold and/or the determined quality factor peak frequency threshold to the measured quality factor value - meaning the quality factor value measured prior to the ping step 420 - and/or the measured quality factor peak frequency. By comparing the value, it is also possible to detect foreign matter placed in the filling area.

The transmitter may control power transmission according to the foreign matter detection result. For example, when a foreign material is detected, the transmitter may transmit a negative acknowledge packet to the receiver as a response to the foreign material detection status packet. Accordingly, power transmission may be stopped, but is not limited thereto.

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

For example, when a foreign substance is detected, the transmitter may transmit a NACK packet (Negative acknowledge packet) to the receiver in response to the foreign substance detection status packet (FOD Status Packet). Accordingly, power transmission may be stopped, but is not limited thereto.

When the foreign matter is detected, the transmitter may receive an end of charge message from the receiver, and may enter the selection step 410 accordingly.

When a foreign substance is detected in the negotiation step 440, the transmitter according to another embodiment of the present invention 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 transmission power, go through the correction step 450, and enter the power transmission step 460 (S407 and S409).

In detail, when the foreign matter is not detected, the transmitter determines the strength of the power received at the receiving end when the transmitter enters the calibration step 450, and measures the power loss between the transmitting end and the receiving end to determine the strength of the power to be transmitted at the transmitting end. can do.

For example, the transmitter may determine the received power intensity of the receiver based on the received power intensity information fed back from the receiving end during power transmission. That is, in the calibration step 450, the transmitter may predict (or calculate) the power loss based on the intensity difference between the transmitted power at the transmitting end and the received power at the receiving end.

In the power transmission step 460, the transmitter receives an unwanted packet (unexpected packet), a desired packet is not received for a predefined time (time out), or a violation of a preset power transmission contract occurs (power transmission step 460). transfer contract violation), when charging is completed, the selection step 410 may be entered (S410).

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

The power transmission contract described above may be established based on state and characteristic information of a transmitter and a receiver.

For example, the transmitter status information may include information on maximum transmittable power and the maximum number of receivers that can be accommodated, and the receiver status information may include information on required power.

The wireless power transmitter according to an embodiment of the present invention may operate in one of the second power transfer modes among the first power transfer modes based on the guaranteed power required by the wireless power receiver.

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

Here, guaranteed power settable according to the second power transfer mode may be greater than guaranteed power settable in the first power transfer mode.

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

In detail, FIG. 5 is a diagram for explaining a foreign matter detection procedure in a second power transmission 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 an internal memory (S502).

The wireless power transmitter 510 may enter the ping phase and perform the detection signal transmission procedure described in 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 the negotiation phase and receive a foreign matter 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 the presence or absence of a foreign substance based on the reference quality factor value included in the foreign substance detection state packet (S507).

For 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 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 a foreign material exists in the charging area.

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

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

Here, the power of a certain intensity or more may be 5W as a standard, but is not limited thereto, and is designed by those skilled in the art and the electronic device equipped with the wireless power receiver 510 and (or the battery/load connected to the wireless power receiver 510) may be defined differently depending on

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

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

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

The power supply 660 may include at least one of an AC/DC converter and a DC/DC converter according to 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 that converts AC power to DC power using a switching transistor, filter, rectifier, etc. . Here, the rectifier and filter may be configured independently and placed between the AC power supply and the SMPS.

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

In many cases, the stability and precision of electronic circuit operation depend on the quality of the power supply. In general, methods for converting and supplying stable power from batteries and commercial AC power include a series regulator method and a switched mode method.

The linear control method used in TV receivers or CRT monitors has simple surrounding circuits and is inexpensive, but has disadvantages in that it generates a lot of heat, has low power efficiency, and is bulky.

On the other hand, the switching mode method has the advantage of generating little heat, high power efficiency, and small volume, but has the disadvantage of being expensive, having a complicated circuit, and generating output noise and electromagnetic interference due to high-frequency switching.

As another example, a variable switching mode power supply (SMPS) may be used as the power supply 660 . The variable SMPS generates a DC voltage by switching and rectifying an AC voltage of several tens of Hz band 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 transmission controller (Tx Controller).

The variable SMPS controls the supply voltage according to the output power level of the power amplifier - that is, the inverter 530 - so that the power amplifier of the wireless power transmitter can always operate in the saturation region with high efficiency, so that the maximum efficiency is achieved at all output levels. can keep

In the case of using a commonly used commercial SMPS instead of a variable SMPS, a variable DC/DC converter may be additionally used.

Commercial SMPS and variable DC/DC converters can maintain maximum efficiency at all output levels by controlling the supply voltage according to the output power level of the power amplifier so that the power amplifier can operate in the saturation region with high efficiency. 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) at a constant level to an AC voltage according to a switching pulse signal in the band of several MHz to several tens of MHz received through the gate driver 620, that is, a pulse width modulated signal. By converting to , it is possible to generate AC power to be transmitted wirelessly.

At this time, the gate driver 620 generates 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 (Ref_CLK) signal supplied from the controller 610. can

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, and the inverter 630 Different numbers of PWM signals may be supplied for each inverter type according to the design form of .

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

On the other hand, 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 for controlling each switch. It can be received from the driver 620.

The transmission antenna 640 includes at least one power transmission antenna (not shown) for wirelessly transmitting the AC power signal received from the inverter 630 - for example, an LC resonance circuit - and a matching circuit for impedance matching (not shown) City) may be configured including.

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

The sensor 670 measures the intensity of power/voltage/current input from the inverter 630 or (and) the intensity of power/voltage/current flowing through the transmission coil provided in the transmission antenna 640, and a specific location inside the wireless power transmitter. It may be configured to include various sensing circuits for measuring temperature and/or temperature change in -eg, which may include a transmission coil, a charging bed, a control circuit board, and the like. Here, information sensed by the sensor 670 may be transmitted to the controller 610 .

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

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 transmission antenna 640.

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

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

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

When the controller 610 detects an object placed in the charging area in the selection step 410, the controller 610 may temporarily stop 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 .

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

After entering the power transmission step 460 , the controller 610 may stop power transmission and enter the selection step 410 when a power transfer end packet is received.

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

Also, the controller 610 may calculate (or estimate) a 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 foreign matter based on the calculated (or estimated) power loss.

Also, the controller 610 may measure a 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 existence of a foreign substance based on the measured temperature change.

In addition, the controller 610 may perform a procedure for determining whether a foreign material exists based on a temperature change based on a result of determining whether a foreign material exists based on power loss.

In addition, when the FOD status packet is received in the negotiation step 440, the controller 610 according to the present invention determines a threshold value for detecting foreign matter based on the received FOD status packet, and determines the presence of foreign matter based on the determined threshold value. You can judge whether or not.

When a power transfer end packet including a ripping code or an overheating code is received through the demodulator 680 in the power transmission step 460, the controller 610 stops power transmission and enters the selection step 410 to perform ripping. You can also run a timer.

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

When a power transfer end packet including a ripping code or an overheating code is received after identification and configuration of the detected receiver are completed, the controller 610 may reset the ripping time and then return to the selection step 410 .

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 the controller 610 in one of the first power transfer mode and the second power transfer mode based on the result of determining whether the foreign matter is present in the negotiation step 440 .

Here, the guaranteed power (or maximum transmit power) of the second power transfer mode may be set higher than that of 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. It should be noted that power may be set differently.

If the foreign matter exists as a result of determining whether or not the foreign matter exists in the negotiation step 440, the controller 610 adjusts the guaranteed power level from the second level corresponding to the second power transfer mode to the second level corresponding to the first power transfer mode. It can be changed to 1 level.

That is, the controller 610 may adjust the guaranteed power downward when it is determined that the foreign matter is present in the negotiation step 440 . Through this, it is possible to prevent damage to the device due to overheating caused by foreign substances during high power transmission.

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

If the correction step 450 is performed in the first power transfer mode despite the presence of foreign matter in the charging area, the method for detecting foreign matter based on the power loss has a problem in that accuracy is low.

In general, the calibration step 450 is a procedure performed assuming that no foreign matter is present. Therefore, if the correction step 450 is performed despite the presence of foreign matter in the charging area, the method for detecting foreign matter based on power loss has a problem in that accuracy is low and unreliable.

If, after entering the first power transmission mode, the foreign matter is not detected through the foreign matter detection method based on the power loss and/or the foreign matter detection method based on the temperature change, the controller 610 performs the operation of FIG. 4 described above. A renegotiation phase 470 may be entered.

When a power transmission contract is finalized according to a result of renegotiation with the wireless power receiver, the controller 610 may change an operation mode according to the determined power transmission contract.

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 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 an operating mode. may be switched from the first power transfer mode to the second power transfer mode.

As described in the foregoing embodiments, the wireless power transmitter 600 according to the present invention has the advantage of continuously charging even when it is determined that a foreign substance is present even though no foreign substance actually exists.

In detail, when the wireless power transmitter 600 determines that a foreign substance is present even though there is no actual foreign substance during operation in the initial second power transmission mode, the wireless power transmitter 600 does not immediately stop charging and removes the power transmission mode. Charging can be maintained by switching from the second power transfer mode to the first power transfer mode.

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

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

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

FIG. 7 is a diagram for explaining the transmission antenna configuration of FIG. 6 according to an embodiment of the present invention.

Referring to FIG. 7 , a 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 transmission coil—that is, first through Nth coils.

The coil selection circuit 710 may include a switching circuit configured to transfer the output current I_coil of the inverter 630 to one or at least one of the transmission coils included in the coil assembly 720 .

For example, the coil selection circuit 710 may include first through Nth switches, one end of which is connected to an inverter output terminal and the other end of which is connected to a corresponding coil.

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

The demodulator 680 may demodulate a signal between the coil assembly 720 and the resonant capacitor 730, wherein the signal is an amplitude modulated signal, and transmit the demodulated signal to the controller 610.

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

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

The wireless power receiver 800 shown 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 receiving antenna 810 . The rectifier 820 may convert AC power received through the receiving antenna 810 into DC power and transmit the converted 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 DC power with a specific intensity required by the load 850 .

The sensing unit 840 may measure the intensity of the output DC power of the rectifier 820 and provide the measurement result to the main control unit 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 receiving antenna 810 according to wireless power reception and transmit the measurement result to the main controller 880 .

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

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

When a packet is received from the main controller 880, the modulator 870 may generate an amplitude modulated signal corresponding to the received packet using AC power received through the reception antenna 810 and a switch provided therein. At this time, the wireless power transmitter 600 may demodulate the signal amplitude-modulated by the wireless power receiver 800 through the demodulator 680 provided therewith.

For 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 to correspond to the received signal strength packet. .

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

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

For example, when the internal temperature exceeds a predetermined reference value, the main control unit 880 controls the switch 840 - for example, switches OFF - so that the output DC power of the DC/DC converter 830 is supplied to the load 850. It can also be controlled not to be passed on. In this case, the main controller 880 may transmit a power transmission stop packet including an overheating code to the wireless power transmitter 600 through the modulator 1070 .

As another example, the main control unit 880 may interwork with a power management element that controls internal power of an electronic device equipped with the wireless power receiver 800 - for example, a Power Management IC (PMIC).

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

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

Upon entering the negotiation step 440, the wireless power receiver 800 according to an embodiment of the present invention may generate and transmit a 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 or not a foreign material exists based on a reference quality factor value included in the foreign material detection status packet.

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

Through this, the wireless power transmitter 600 and the wireless power receiver 800 may perform bi-directional communication. As an example, bidirectional communication may be time division communication in which a packet transmittable time in a wireless power transmitter and a packet transmittable time in a wireless power receiver are divided, but is not limited thereto.

9 is a diagram for explaining a power transmission control method according to whether or not a foreign substance is detected in a wireless power transmitter according to the prior art.

Upon receiving the negotiation request packet from the wireless power receiver, the wireless power transmitter may transmit a grant packet to enter the negotiation phase 440.

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

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

The wireless power transmitter may determine whether a foreign substance exists (S902). Here, the wireless power transmitter determines the quality factor threshold based on the quality factor value measured before entering the ping step 420 after object detection in the selection step 410 and the reference quality factor value received in the negotiation step 440. By comparing the values, the presence of foreign matter can be determined.

As a result of the determination, if the foreign matter does not exist, 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 calibration phase 450 from the negotiation phase 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 described above, if a foreign substance exists, the wireless power transmitter may transmit a NACK signal in response to the foreign substance detection status packet (S908).

When the NACK signal is received in response to the foreign matter detection status packet, the wireless power receiver may generate power at its output terminal of a predetermined reference value, for example, 5W, until the power signal received from the wireless power transmitter is completely removed. However, it can be controlled so as not to exceed - but is not limited thereto.

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

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

Transmitting power in the second power transmission mode in a state in which foreign substances are disposed in the charging area may increase the risk of overheating of the device.

Accordingly, when the conventional wireless power transmitter determines that a foreign substance is present, it blocks entry to the power transmission step 460, stops 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 equipped LCR meter, the mechanical design of the wireless power transmitter and wireless power receiver, and the design difference of the coils mounted on each, and the transmission coil Depending on the separation distance between the P and the receiving coil—that is, Z distance—and the location of the wireless power receiver disposed in the charging area—that is, XY displacement—the foreign substance may not actually exist, but it may be mistakenly determined that the foreign substance exists.

If, in spite of the fact that there is no foreign matter, unconditionally stopping power transmission and then returning to the selection step may cause serious inconvenience to the user.

In particular, a wireless power receiver applied to a smartphone or the like may be designed so that a shielding material having high magnetic permeability is applied to reduce the thickness of the corresponding product and the thickness of the receiving coil is reduced as much as possible.

In this case, the resistance R can become very large and the quality factor Q can become very small. In addition, when a metal housing is applied to the corresponding product, the quality factor Q may be further lowered.

This may increase an error probability for determining the presence or absence of foreign matter in the wireless power transmitter.

For example, when an error in determining the presence of a foreign substance occurs, the quality factor Q is measured low even though the smartphone is placed in the charging area, and the smartphone is judged as a foreign substance. circumstances may be included.

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

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

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, but this is only one embodiment, and the corresponding packet is transmitted through out-of-band communication. can also be exchanged.

Referring to FIG. 10A, a packet format 1000 used for information exchange between a wireless power transmitter 10 and a wireless power receiver 20 is used to obtain synchronization for demodulation of a corresponding packet and to identify the correct start bit of the corresponding packet. A preamble (1010) field for transmission, a header (1020) field for identifying the type of message included in the packet, and a message (Message, 1030) field and a checksum (Checksum, 1040) field for checking whether an error has occurred in the corresponding packet.

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

In addition, the types of packets transmittable for each step shown in FIG. 4 may be defined by the value of the header 1020, and some header 1020 values are defined to be common in different steps of the wireless power transfer procedure. It can be. For example, an end power transfer packet for stopping power transmission of the wireless power transmitter in the ping step 420 and the power transfer step 460 may be defined with the same header 1020.

The message 1030 includes data to be transmitted by the transmitter of the corresponding packet.

For example, data included in the field of the message 1030 may be a report, a request, or a response to the other party, 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 has transmitted the packet and receiver identification information for identifying a receiver to receive the packet. there is.

Here, the transmitter identification information and the receiver identification information may include, but are not limited to, IP address information, medium access control (MAC) address information, product identification information, etc. Information is enough.

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

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

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

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

For example, referring to FIG. 10A , the message 1030 field of the foreign matter detection status packet, as shown in reference number 1050, when the mode 1032 field is set to binary '00', the foreign matter detection value 1033 If the Reference Resonance Quaility Factor Value is recorded in the field and the mode 1033 field is set to binary number '01', the Reference Resonance Frequency is recorded in the Reference Foreign Matter Detection Value 1033 field. It 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 according to the reference resonance frequency.

As another example, referring to FIG. 10B , the message 1030 field of the foreign matter detection status packet is a reference foreign matter detection value 1033 when the mode 1032 field is set to binary number '00' as shown by reference number 1060. ) field and the mode 1033 field is set to '01', the reference resonance frequency is recorded in the reference foreign matter detection value 1033 field. It can be.

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

For example, if the reference foreign matter detection value 1033 field is the reference resonant frequency, the actual frequency value may be calculated by dividing the value of the reference foreign matter detection value 1033 field by 2 and adding 36. Accordingly, the reference resonant frequency recorded in the reference foreign matter detection value 1033 field is in units of 0.5 kHz and may have a range of 36 to 163.5 kHz.

Here, the reference quality factor may be, for example, 100 kHz, a predefined reference operating frequency in a state where the wireless power receiver is placed in the charging area of the wireless power transmitter for authentication with the power turned off, but is not limited thereto. It can be defined as a quality factor value measured in correspondence with -. In detail, as for the standard quality factor, the smallest value among the quality factor measured when the receiver is placed in the center of the charging area and the quality factor measured after moving +/- 5 mm from the center along the X axis and Y axis, respectively, corresponds to the receiver. It can be determined as a standard quality factor to be.

In addition, the reference resonant frequency may be defined as a resonant frequency of a transmission coil in a state in which the corresponding wireless power receiver is placed in a charging area of the wireless power transmitter for authentication with the power turned off.

At this time, the reference resonant frequency is measured in a state in which foreign substances are not disposed in the charging area of the wireless power transmitter for authentication. Here, the transmitter (or transmission coil) may mean a reference transmission coil.

For example, a reference transmission coil may have an authentication coil design for determining a reference value.

Depending on its version, the wireless power receiver according to an embodiment of the present invention may sequentially transmit foreign matter detection state packets having two different reference foreign matter detection values at a predetermined time interval during the negotiation phase.

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

According to an embodiment, the wireless power receiver sets the mode 1032 field to binary number '00' and transmits the reference resonance quality factor or the reference quality factor to the wireless power transmitter first, and then sets the mode 1032 field to binary number '01'. ' to transmit the reference resonance frequency value to the wireless power transmitter, but this is only one embodiment, and in another embodiment, the reference resonance quality factor or reference quality factor may be transmitted after the reference resonance frequency is transmitted first. there is.

The wireless power transmitter may detect the foreign material using a bandwidth calculated based on a reference foreign material detection value included in the received foreign material detection status packet and a bandwidth calculated using the quality factor and 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 field values included in the received foreign matter detection status packet are normal, and if the received packet is not normal as a result of the checking, it may transmit an ND response to the wireless power receiver. That is, when there is no appropriate response defined for the received packet, the wireless power transmitter may transmit an ND response to the wireless power receiver and disregard the contents of the received packet.

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

The foreign matter detection procedure according to this 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 matter detection status packets, the wireless power receiver controls power not to be provided to the output terminal of the wireless power receiver until power signal transmission from the wireless power transmitter is stopped. can do.

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

In addition, when all ND responses are received in response to a plurality of foreign matter detection status packets, the wireless power receiver controls power not to be provided to the output terminal of the wireless power receiver until power signal transmission from the wireless power transmitter is stopped. can do.

After entering the negotiation phase, the wireless power transmitter may stop power signal transmission and then enter the selection phase when a normal foreign matter detection state packet is not normally received within a predetermined time. In this case, when the power signal is no longer detected in the negotiation step, the wireless power receiver may also 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 resonant frequency bandwidth to the wireless power transmitter through a foreign matter detection status packet.

As shown in reference numeral 1070 of FIG. 10C , when the value of the mode 1032 is the binary number '00', the reference resonant 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 in FIGS. 10A to 10C is just one embodiment and is mapped to another mode 1032 value according to design. The detection value 1033 may be different.

As another example, the wireless power receiver may transmit information about 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 in reference numeral 1080 of FIG. 10D, when the mode 1032 value is the binary number '00', the reference quality factor is recorded in the reference foreign matter detection value 1033 field, and the mode 1032 value is the binary number '01'. When , the reference resonance frequency is recorded in the reference foreign matter detection value 1033 field, and when the mode 1032 value is the binary number '10', the reference resonance frequency bandwidth may be recorded in the 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 in FIGS. 10A to 10D is just one embodiment and is mapped to another mode 1032 value according to design. The detection value 1033 may be different.

In addition, the foreign material detection status packet described with reference to FIGS. 10A to 10D is illustrated as including one reference foreign material detection value 1033 field, but the foreign material detection status packet according to another embodiment has a plurality of different reference foreign matter standards. A detection value may be defined to be transmitted through one packet.

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

Upon receiving the negotiation request packet from the wireless power receiver, the wireless power transmitter may transmit a grant packet to enter the negotiation phase 440.

Referring to FIG. 11 , in the negotiation step 440, the wireless power transmitter may receive a foreign object detection (FOD) status packet from the wireless power receiver (S1110).

For example, as shown 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. foreign matter detection status packet can be received.

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

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

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

The wireless power transmitter measures the 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. Real capacitors and inductors used in electrical circuits are not ideal components that only have capacitance or inductance. However, when connected in series with a resistor, they can be considered very approximately ideal capacitors and inductors. This resistance is defined as equivalent series resistance (ESR).

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

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

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.

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

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

The quality factor value Q in an ideal RLC series circuit and a tuned radio frequency receiver (TRF receiver) can be calculated according to the following formula.

이고,

는 공진 주파수를 의미한다.Here, R, L, and C mean storage, inductance, and capacitance, respectively,

ego,

denotes the resonant frequency.

이므로,

이 된다.

Because of,

becomes

ESR is always AC resistance measured at standard frequency, and high ESR can cause components to age, heat up, and increase ripple current.

로 계산될 수 있다.

can be calculated as

로 계산되고, ESR_measured는

로 계산될 수 있다.Therefore, in the above embodiment, ESR_reference is

, and ESR_measured is

can be calculated as

: 무선충전기가 측정한 Q-factor

: Q-factor measured by wireless charger

: 무선 충전기가 측정한 Peak frequency

: Peak frequency measured by wireless charger

: 무선충전기 타입 코일에서의 기준 Q-factor(수신기 배치, 이물질 없는 상태)

: Standard Q-factor in wireless charger type coil (receiver arrangement, condition without foreign matter)

: 무선충전기 타입 코일에서의 기준 Peak frequency(수신기 배치, 이물질 없는 상태)

: Reference peak frequency in wireless charger type coil (receiver arrangement, condition without foreign matter)

: 무선충전기의 공진 캐패시터의 캐패시턴스

: Capacitance of the resonance capacitor of the wireless charger

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

이 0.2보다 크면 이물질이 존재하는 것으로 판단할 수 있다. The wireless power transmitter according to an embodiment may determine that a foreign substance is present when a ratio between ESR_referenc and ESR_measured exceeds a predefined ratio threshold. Here, the ratio threshold may be determined by experimental results. For example,

If this is greater than 0.2, it can be determined that foreign matter is present.

The wireless power transmitter according to another embodiment of the present invention may determine whether or not a foreign substance is present using a reference resonance bandwidth and a measurement resonance bandwidth.

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

In the following description, an embodiment in which the wireless power transmitter determines whether or not a foreign substance is present based on a change in a resonance frequency bandwidth will be mainly described.

The wireless power transmitter may determine whether a foreign substance is present (S1120). Here, the wireless power transmitter may determine whether or not a foreign substance is present based on a change in the resonant frequency bandwidth.

As a result of the determination, if the foreign matter does not exist, 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.

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

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

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

Here, detailed configurations of the first power transfer control procedure and the second power transfer control procedure will become clearer through description of the drawings to be described later.

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

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

Here, detailed configurations of the first power transfer control procedure and the second power transfer control procedure will become clearer through description of the drawings to be described later.

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

Upon receiving the negotiation request packet from the wireless power receiver, the wireless power transmitter may transmit a grant packet to enter the negotiation phase 440.

Referring to FIG. 12 , in the negotiation step 440, the wireless power transmitter may receive a foreign object detection (FOD) status packet from the wireless power receiver (S1201).

For example, as shown 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. A foreign matter detection status packet may be received, but is not limited thereto.

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

The wireless power transmitter may determine whether a foreign substance exists (S1202). Here, the wireless power transmitter may determine whether or not a foreign substance is present based on a change in the resonant frequency bandwidth.

As a result of the determination, if the foreign matter does not exist, 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 a first power transmission control procedure (S1140).

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

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

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

The wireless power transmitter may receive a guaranteed power packet including information on 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).

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

The wireless power transmitter may enter a calibration step 450 and 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 described above, if a foreign substance exists, the wireless power transmitter may transmit a second response signal in response to the foreign substance 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 matter detection status packet, the wireless power receiver may perform a 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 (eg, 5W) when it is determined that a foreign substance exists.

At 5W, the wireless power transmitter can determine the existence of foreign matter based on a preset boundary value (or threshold value) for power loss, and since it is a predetermined minimum power during transmission and reception, it can set a solid reference value and determine foreign matter there is.

A foreign material detection method different from the foreign material detection method 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 transfer 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. At this time, it should be noted that the wireless power transmitter does not stop transmitting the wireless power signal.

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

When the negotiation end packet is received from the wireless power receiver, the wireless power transmitter may end the negotiation step 440, enter the power transmission step S460, and charge with the preset first power (S1212).

In the embodiment of FIG. 12 described above, it is described that the wireless power transmitter receives the guaranteed power packet and the negotiation end packet while performing the second power transmission control procedure (S1160), but this is only one embodiment, and other embodiments At least one of the guaranteed power packet and the negotiation end packet may not be received by the wireless power transmitter.

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

Here, the calibration step 450 may mean a process of comparing the transmit power of the transmitter and the received power of the receiver to accurately measure values for transmit power and receive power and power loss between the transmitter and the receiver.

At this time, in the second power transmission mode in which the guaranteed power exceeds 5W, since the power loss may change as the transmission power increases, it is predicted (calculated) in advance and the predicted value is reflected when the transmission power changes, thereby reducing the power loss. can be calculated accurately.

However, in the first power transmission mode in which guaranteed power of the minimum power is transmitted, it is not necessary to perform correction because fixed power is set as a target and operated.

In addition, when at least one of transmission power, reception power, and loss power is corrected in the presence of a foreign substance, the effect of the foreign substance is included in the correction, so that the wireless power transmitter does not have the foreign substance even though the foreign substance actually exists. You can increase the probability of deciding that it is not.

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

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

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

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

Hereinafter, for convenience of description, it is described that the wireless power transmitter measures power loss, but this is only one embodiment, and the transmission power measurement result from the wireless power transmitter and the received power measurement result received from the wireless power receiver It should be noted that power loss can be calculated or estimated based on this.

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

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

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

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

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

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

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

It may be determined that there is no foreign material even when the power loss is within a threshold value for a specific time period or when the power loss is within a threshold value after a specific time period has elapsed.

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

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

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

According to the renegotiation result, the wireless power transmitter re-enters the power transmission step 460 and continues to charge the corresponding wireless power receiver.

For example, when a foreign substance is not detected after entering the power transmission step, the wireless power transmitter converts the first power transmission mode to the second power transmission mode through renegotiation to increase the intensity of the transmission power and shorten the charging time. can

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

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

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

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

A wireless power transmitter according to another embodiment may receive temperature information measured by the wireless power receiver at a predetermined period during power transmission. The wireless power transmitter may measure a 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 internally measured first temperature change and the second temperature change measured based on the 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). For example, the wireless power transmitter may determine that a foreign substance is present when the measured temperature change exceeds a predetermined temperature change threshold.

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

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

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

According to the renegotiation result, the wireless power transmitter may re-enter the power transmission step 460 and continue charging.

For example, when a foreign substance is not detected after entering the power transmission step, the wireless power transmitter converts the first power transmission mode to the second power transmission mode through renegotiation to increase the intensity of the transmission power and shorten the charging time. can

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

Referring to FIG. 15 , the wireless power transmitter may enter the power transmission step 460 after 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 power transmission step 460, power loss may be measured based on a received power packet fed back from a wireless power receiver during power transmission.

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

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

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

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

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

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

Here, the location where the temperature change is measured on the wireless power transmitter may be around the transmission coil, but is not limited thereto, and may be measured at other locations of the wireless power transmitter according to design by those skilled in the art.

A wireless power transmitter according to another embodiment may receive temperature information measured by the wireless power receiver at a predetermined period during power transmission. The wireless power transmitter may measure a 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 internally measured first temperature change and the second temperature change measured based on the 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 (S1570). For example, the wireless power transmitter may determine that a foreign substance is present when the measured temperature change exceeds a predetermined temperature change threshold.

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

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

As a result of the determination in step 1570 described above, if no foreign matter exists, the wireless power transmitter may enter a renegotiation step and renegotiate a power transmission contract with the wireless power receiver (S1580). According to the renegotiation result, the wireless power transmitter may re-enter the power transmission step 460 and continue charging.

For example, when a foreign substance is not detected after entering the power transmission step, the wireless power transmitter converts the first power transmission mode to the second power transmission mode through renegotiation to increase the intensity of the transmission power and shorten the charging time. can

In the embodiment of FIG. 15 described above, it is illustrated that the wireless power transmitter performs a foreign matter detection procedure based on power loss and then performs a foreign material detection procedure based on a temperature change according to the determination result. However, the wireless power transmitter according to another embodiment may be implemented to perform a foreign material detection procedure based on a temperature change and then perform a foreign material detection procedure based on power loss according to a determination result.

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

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

(1612)에서 피크 투 피크 전압의 진폭 또는 전압/전류의 진폭이 최대 임을 알 수 있다. Referring to FIG. 16, the resonant frequency

In 1612, it can be seen that the amplitude of the peak-to-peak voltage or the amplitude of the voltage/current is maximum.

, 1613) 및 상한 대역폭 주파수(

, 1614)로 명하기로 한다. 여기서, 3dB 아래인 진폭 값은 최대 진폭 값(1611)의 약 70.7%일 수 있다.There may be two operating frequencies or half power bandwidth frequencies with voltages or currents whose values are 3 dB below the maximum amplitude. For convenience of description below, the two operating frequencies below 3 dB from the maximum amplitude value 1611 are each the lower limit bandwidth frequency (

, 1613) and the upper limit 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 that directly affects the charging efficiency of wireless power, and a 3dB drop in the quality factor may mean that power transmission efficiency (or transmission power) is reduced by half.

- 으로 정의될 수 있다.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 - that is,

- can be defined as

In the embodiment of FIG. 16 described above, it is described that the resonance frequency bandwidth 1615 is determined by frequencies having a voltage or current that is 3 dB below the maximum amplitude value 1611, but this is only one embodiment, A frequency domain having a voltage or current 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 those skilled in the art and the characteristics of the product.

(BW: Bandwidth)는 하기의 수학식 1과 같이, 공진 주파수(

)와 해당 공진 주파수

에서의 품질 인자 값

에 기반하여 산출될 수도 있다.Resonant frequency bandwidth according to another embodiment of the present invention

(BW: Bandwidth) is the resonance frequency (as shown in Equation 1 below)

) and the corresponding resonant frequency

Quality factor value at

may be calculated based on

<수학식 1>

<Equation 1>

는 하기의 수학식 2와 같이 표현될 수 있다.Quality factor values in low power systems

Can be expressed as in Equation 2 below.

<수학식 2>

<Equation 2>

은 하한 대역폭 주파수이고

는 상한 대역폭 주파수이다.here,

is the lower bound bandwidth frequency and

is the upper limit bandwidth frequency.

17 is a flowchart for explaining a foreign matter detection procedure using a resonant frequency bandwidth in a wireless power transmission system according to an embodiment of the present invention.

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

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

Alternatively, the resonance frequency may mean a frequency when the output voltage (coil voltage) to the input voltage of the resonator is maximum.

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

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

The wireless power transmitter 1710 may enter the ping phase and perform the detection signal transmission procedure described in FIG. 3 (S1703).

When the wireless power receiver 1720 is detected, the wireless power transmitter 1710 may enter an identification and configuration phase and 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 phase, it may receive a foreign matter detection status packet from the wireless power receiver 1720 (S1706).

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

The reference resonant frequency according to the present embodiment is the resonant frequency (self resonant frequency) of the transmission coil shifted by the coil, shielding material, instrument, battery, etc. of the receiver in a state where the wireless power receiver 1720 is disposed in the charging area of the transmitter for authentication. can mean

For convenience of explanation, the 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 the reference resonance frequency included in the foreign matter detection state packet and a quality factor at the reference resonance frequency—that is, a reference resonance quality factor—and in step 1702 A resonant frequency bandwidth may be calculated based on the resonant frequency and the resonant quality factor stored in S1707.

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

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

In general, when a foreign material is disposed in the charging area of the wireless power transmitter 1710, as described in FIG. 18 to be described later, the resonance frequency bandwidth has a characteristic that increases rapidly compared to when the foreign material is not disposed.

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

For example, if the difference (or ratio) between the resonance frequency bandwidth and the reference resonance frequency bandwidth exceeds a predetermined threshold value, the wireless power transmitter 1710 may determine that a foreign substance is present in the charging area. .

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

과 기준 공진 주파수 대역폭

의 비율인

는 하기 수학식 3에 의해 계산될 수 있다.resonant frequency bandwidth

and reference resonant frequency bandwidth

which is the ratio of

Can be calculated by Equation 3 below.

<수학식 3>

<Equation 3>

The reference resonant frequency may refer to a resonant frequency of the transmission coil measured in a state in which only the receiver is placed on the charging area of the transmitter (or transmission coil) without any foreign matter.

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

The wireless power transmitter 1710 may generate and transmit a predetermined response packet according to a result of determining whether or not a foreign substance exists to the wireless power receiver 1720.

For example, if it is determined that a foreign substance is present in step 1708 described above, 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 no foreign matter exists, the wireless power transmitter 1710 may generate an ACK response packet and transmit it to the wireless power receiver 1720.

In addition, in step 1708 described above, if 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 it to the wireless power receiver 1720.

When a NACK response or an ND response is received from the wireless power transmitter 1710, the wireless power receiver 1720 uses an electronic device (or battery) through its output terminal until power transmission by the wireless power transmitter 1710 is completely stopped. /load) can be controlled so that power over a certain level is not supplied.

Here, the power of a certain intensity or more may be 5W as a standard, but is not limited thereto, and may vary depending on the design and the electronic device in which the wireless power receiver 1720 is mounted (or the battery/load connected to the wireless power receiver 1720). can be defined as

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

The reference resonant frequency may refer to a resonant frequency of a transmission coil measured in a state in which only a receiver is placed on the transmitter (or transmission coil) without any foreign matter.

The wireless power transmitter 1710 according to another embodiment may receive a foreign matter detection state 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. may be

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

The wireless power transmitter 1710 according to another embodiment may receive a foreign matter detection state packet including a reference resonance frequency bandwidth and determine whether or not a foreign matter is present based on the resonance frequency bandwidth and the reference resonance frequency bandwidth.

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

18 is a diagram for explaining a change pattern of a resonant frequency bandwidth according to whether a foreign material is disposed.

Referring to FIG. 18, reference number 1810 is a graph showing a resonator amplification ratio (Vin/Vout) pattern within an operating frequency band when no foreign matter is disposed between the receiver and the charging area, and reference number 1820 is a graph showing a pattern between the receiver and the charging area. This is a graph showing the resonator amplification ratio (Vin/Vout) pattern within the operating frequency band when there is a foreign substance in .

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

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

Reference numeral 1811 is a resonant frequency bandwidth when no foreign material is placed in the charging area, and reference numeral 1821 shows a resonant frequency bandwidth when no foreign material is placed in the charging area.

에 대응되고, 충전 영역에 이물질이 배치되었을 때의 주파수 대역폭은 상기한 도 17에서 설명된 공진 주파수 대역폭

에 대응될 수 있다.Here, the frequency bandwidth when no foreign material is disposed in the charging area is the reference resonance frequency bandwidth described in FIG. 17 above.

Corresponds to , and the frequency bandwidth when the foreign matter is placed in the charging area is the resonant frequency bandwidth described in FIG. 17 above.

can correspond to

(1811)보다 공진 주파수 대역폭

(1821)이 커진다.As shown in FIG. 18 , it can be seen that the resonant frequency bandwidth increases when a foreign material is disposed in the charging area. That is, the reference resonant frequency bandwidth

(1811) resonant frequency bandwidth

(1821) grows.

In addition, when a foreign material is placed in the charging area, the resonance frequency at which the quality factor is maximum may shift to the right, as shown in reference numeral 1830 . That is, the resonant frequency 1832 when the receiver and the foreign material are placed in the charging area increases compared to the resonant frequency 1831 before the foreign material is placed in the charging area (when only the receiver is present). Alternatively, even when the distance between the receiver and the charging area increases, the resonant frequency may increase while reducing the effect of the shielding agent.

The wireless power transmitter according to an embodiment of the present invention may determine that a foreign material is present in the charging area when the increase amount (or increase rate) of the resonant frequency bandwidth exceeds a predetermined threshold value (or predetermined threshold percentage).

과 기준 공진 주파수 대역폭

의 차이 값이 소정 임계치를 초과하면, 무선 전력 송신기는 충전 영역에 이물질 존재하는 것으로 판단할 수 있다. 반면, 공진 주파수 대역폭

과 기준 공진 주파수 대역폭

의 차이 값이 소정 임계치 이하이면, 무선 전력 송신기는 충전 영역에 이물질 존재하지 않는 것으로 판단할 수 있다. As an example, the resonant frequency bandwidth

and reference resonant frequency bandwidth

If the difference value of exceeds a predetermined threshold value, the wireless power transmitter may determine that a foreign substance exists in the charging area. On the other hand, the resonant frequency bandwidth

and reference resonant frequency bandwidth

If the difference value of is less than a predetermined threshold value, the wireless power transmitter may determine that there is no foreign matter in the charging area.

에서 공진 주파수 대역폭

으로의 변화 비율이 소정 임계 비율을 초과하면, 무선 전력 송신기는 충전 영역에 이물질 존재하는 것으로 판단할 수 있다. 반면, 기준 공진 주파수 대역폭

에서 공진 주파수 대역폭

로의 변화 비율이 소정 임계 비율 이하이면, 무선 전력 송신기(1710)는 충전 영역에 이물질 존재하지 않는 것으로 판단할 수 있다.As another example, the reference resonant frequency bandwidth

resonant frequency bandwidth at

If the rate of change to ? exceeds a predetermined threshold rate, the wireless power transmitter may determine that a foreign substance is present in the charging area. On the other hand, the reference resonant frequency bandwidth

resonant frequency bandwidth at

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

As another example, the wireless power transmitter may determine whether or not a foreign material is present based on a movement of a resonant frequency having a maximum quality factor.

For example, referring to FIG. 18 , if the increase amount (or increase rate) of the resonant frequency 1822 relative to the reference resonant frequency 1821 is greater than or equal to a predetermined threshold value (or threshold ratio), the wireless power transmitter detects that foreign matter is placed in the charging area. can be judged to be

However, in the case of a foreign substance made of a specific material—for example, a foreign substance made of iron—the magnetic permeability is very high and the effect on the inductance of the transmission coil is very small. Therefore, there is a problem in that it is difficult to distinguish the presence or absence of a foreign material by comparing the size of the resonant frequency shift according to the arrangement of the foreign material.

In addition, the quality factor may not be classified as a foreign substance due to a small difference in resistance components for aluminum-based foreign substances.

If the bandwidth comparison, which is a unified criterion by using the resonance frequency and the quality factor together, has the advantage of being able to utilize two mutually complementary variables.

The wireless power transmitter according to another embodiment of the present invention may be controlled to perform a foreign matter detection procedure based on a resonant frequency bandwidth change according to a foreign matter detection result based on a resonant frequency movement.

For example, if the measured resonant frequency change amount (or change rate) is greater than or equal to a predetermined threshold value (or threshold ratio), the wireless power transmitter does not perform a separate resonant frequency bandwidth change-based foreign substance detection procedure, and foreign substances are present in the charging area. It can be judged that

On the other hand, if the measured resonant frequency change amount (or change rate) is less than a predetermined threshold value (or threshold ratio), the wireless power transmitter performs a foreign matter detection procedure based on the resonant frequency bandwidth change to determine the presence of foreign matter.

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

First, in the case of the quality factor, not only does the value vary widely depending on the configuration and type of the wireless charging device, but in the case of some smartphones equipped with wireless power receivers, other configurations of the smartphone (eg friendly metal) As a result, the quality factor value may be too small even if foreign matter is not disposed. When the quality factor is small, the difference in quality factor values according to the presence or absence of foreign substances is small, and the probability of misjudgment increases.

This misjudgment can cause heat generation as well as damage to the device. Alternatively, even though there is no foreign matter, the smartphone may be judged as a foreign matter and charging may not be started.

Second, in the case of the quality factor, there is a problem in that the amount of change in the value of the quality factor measured before and after placement of the foreign material is very small depending on the type of the foreign material.

If a foreign material having a small change in 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 area. This misjudgment not only directly causes heat generation, but also may cause device damage and power loss.

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

In this case, the wireless power transmitter may misjudge that a foreign material is disposed in the charging area even though the foreign material is not actually disposed in the charging area. Since charging is stopped, this may cause inconvenience to the user.

과 공진 주파수 대역폭 변화량

중 어느 것이 더 큰지를 설명하기로 한다. Hereinafter, the amount of change in the quality factor value when a foreign substance is placed in the charging area of the wireless power transmitter

Over-resonance frequency bandwidth change amount

Let's explain which one is bigger.

과 공진 주파수 대역폭 변화량

의 차이 값은 하기 수학식 4로 표현될 수 있다.Change in quality factor value

Over-resonance frequency bandwidth change amount

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

<수학식 4>

<Equation 4>

은 측정 품질 인자 값이고,

는 기준 품질 인자 값이다.

은 측정 공진 주파수이고,

은 기준 공진 주파수이다.here,

is the measurement quality factor value,

is the reference quality factor value.

is the measured resonant frequency,

is the reference resonant frequency.

이고,

가 된다.If there is a foreign substance in the charging area,

ego,

becomes

가 1이라고 가정하면-즉, 이물질 배치에 따라 공진 주파수 이동이 없다고 가정하면-,

가

이 되어,if,

Assuming that is 1 - that is, assuming that there is no resonant frequency shift with the foreign material placement -,

go

become,

로 표현될 수 있다.Equation 4 above is

can be expressed as

이

보다 작다고 가정하면, here,

this

Assuming it is smaller than

이 되고,

이므로,

이 된다. Equation 4 above is

becomes,

Because of,

becomes

이 항상 품질 인자 값의 변화량

보다 클 수 있다.Therefore, the amount of change in the resonant frequency bandwidth

This is always the amount of change in the value of the quality factor.

can be bigger

가 1보다 크다고 가정하면-즉, 이물질 배치에 따라 공진 주파수 이동이 있다고 가정하면-,

가

로 표현될 수 있다.if,

Assuming that is greater than 1 - that is, assuming that there is a resonant frequency shift depending on the foreign matter placement -,

go

can be expressed as

, 이물질 배치에 따라 공진 주파수 이동이 있을 때의 공진 주파수 대역폭을

라 가정한다.Hereinafter, the resonant frequency bandwidth when there is no resonant frequency shift depending on the placement of the foreign matter is

, the resonant frequency bandwidth when there is a resonant frequency shift according to the placement of foreign matter

Assume that

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

<수학식 5>

<Equation 5>

이

보다 작으면,At this time,

this

If less than

이 되므로,

는 항상

보다 크다.Equation 5 above is

becomes,

is always

bigger than

이 항상 품질 인자 값의 변화량

보다 큰 것을 알 수 있다.Considering the above description, when a foreign substance is placed in the charging area, the amount of change in the resonant frequency bandwidth

This is always the amount of change in the value of the quality factor.

larger ones can be found.

과

는 동일하고,

과

도 동일하게 된다. 따라서, 공진 주파수 대역폭 변화량

이 항상 품질 인자 값의 변화량

은 서로 같다.In Equation 5 above, if no foreign matter is placed in the charging area,

class

is the same,

class

also becomes the same. Therefore, the amount of change in the resonant frequency bandwidth

This is always the amount of change in the value of the quality factor.

are equal to each other

Looking at the above, it can be seen that the change in BW and Q is the same when there is no foreign matter, and the change in BW is always greater than the change in Q when the foreign matter is present. This means that when determining whether or not a foreign material is present, it is easier for BW to determine that a foreign material is present.

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

Referring to FIG. 19 , a wireless power transmitter 1900 may include an antenna 1910, a power converter 1920, a modem 1930, a memory 1950, and a controller 1960.

When an AC power signal is received from the power converter 1920, the antenna 1910 can output it wirelessly through a resonant circuit provided therein.

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 modem 1930 may demodulate a signal received through the antenna 1910 and transmit the demodulated signal to the controller 1960. For example, the modem 1930 may demodulate an amplitude-modulated signal detected through the antenna 1910, that is, an in-band signal, and transmit the demodulated signal to the controller 1960.

In addition, the modem 1930 may modulate the signal generated by the controller 1960 - for example, but not limited to amplitude modulation - and transmit the signal to the antenna 1910.

In the description of FIG. 19 above, the modem 1930 is described as modulating or demodulating an in-band communication signal, but this is only one embodiment, and the modem 1930 according to another embodiment performs short-range wireless communication. It can also process signals transmitted and received through it. To this end, the antenna 1910 may additionally include a communication antenna for short-range wireless communication as well as a charging antenna for wireless power transmission.

When the modem 1930 enters the negotiation phase, it can demodulate and transmit the foreign matter detection status packet to the controller 1960.

As an example, the wireless power transmitter transmits a reference resonance quality factor (or reference quality factor and/or reference resonance quality factor) as shown in FIGS. 10A to 10B through a foreign matter detection status packet. A frequency (Reference Resonance Frequency) can be received.

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

As another example, the wireless power transmitter provides a Reference Resonance Quality Factor (or a Reference Quality Factor and/or a Reference Resonance Frequency) and a Reference Resonance Frequency through a foreign matter detection status packet. Bandwidth may be received.

Controller 1960 can measure the quality factor value.

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

The controller 1960 may determine the resonant frequency using the amplitude of the peak voltage applied to the transmission coil.

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

Also, 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 amount of change (or rate of change) of the resonant frequency bandwidth.

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

The resonant frequency bandwidth change ratio may be calculated by subtracting the reference resonant frequency bandwidth from the resonant frequency bandwidth and dividing it by the reference resonant frequency bandwidth.

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

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

For example, when the calculated resonant frequency bandwidth change amount (or change rate) exceeds a predetermined threshold value (or threshold ratio), the controller 1960 may determine that a foreign material is present in the charging area.

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

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

As another example, the controller 1960 may determine the threshold based on the reference resonant frequency bandwidth. This threshold is a unified threshold that can compare the quality factor and the resonant frequency at once. The controller 1960 may compare the unified threshold and the measured resonant frequency bandwidth to determine the presence or absence of foreign matter.

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

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

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

The memory 1950 may store programs necessary for the operation of the wireless power transmitter 1900 and various register values.

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.

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

20 shows foreign material detection test results for various foreign materials for each transmitter type.

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

In detail, the results of this experiment show that four different foreign substances—that is, FO#1, FO#1, It shows the change pattern of the measured quality factor value and the change pattern of the resonance frequency bandwidth for FO#2, FO#3, and FO#4-.

Referring to reference number 2010, it is shown that when foreign substances are placed in the filling area, the quality factor value for all foreign substances is lowered.

Also, reference numeral 2010 shows that the rate at which the quality factor value is lowered is different depending on the type of foreign matter and the type of transmitter.

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

Referring to reference number 2020, when a foreign material is placed in the charging area, the resonance frequency bandwidth increases regardless of the type of transmitter and the type of foreign material.

Also, reference numeral 2020 shows that the rate at which the resonance frequency bandwidth increases is different depending on the type of transmitter and the type of foreign matter.

In particular, reference numeral 2010 shows that the increase rate of the resonance frequency bandwidth is the lowest 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 placed in the charging area 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. there is.

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

(2014)보다 최소 공진 주파수 대역폭 변화 비율

(2021)이 2배 이상 큰 것을 알 수 있다.Referring to drawing numbers 2010 and 2020, the minimum quality factor change rate

(2014) minimum resonant frequency bandwidth change ratio

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

Therefore, the foreign material detection method based on the resonant frequency bandwidth according to the present invention has the advantage of being able to more accurately detect the foreign material compared to the conventional foreign material detection method based on the quality factor value.

21 shows foreign material detection test results for various foreign materials for each receiver type.

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

In detail, the results of this experiment show that five different receivers of different types—namely, first to fifth receivers—and four different foreign substances—namely, FO#1, FO#2, and FO#—in the charging area of a specific transmitter. 3, shows the change pattern of the measured quality factor value and the change pattern of the resonance frequency bandwidth when FO#4- is placed.

Referring to reference numeral 2110, it is shown that when a foreign substance is placed in the charging area, the quality factor value is lowered regardless of the type of receiver and the kind of foreign substance.

Also, reference numeral 2110 shows that the rate at which the quality factor value is lowered is different depending on the type of foreign matter and the type of receiver.

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

Referring to reference numeral 2120, when a foreign material is placed in the charging area, the resonant frequency bandwidth increases regardless of the type of receiver and the type of foreign material.

Also, reference numeral 2120 shows that the rate at which the resonant frequency bandwidth increases is different depending on the type of receiver and the type of foreign matter disposed in the charging area.

In particular, reference numeral 2120 shows that the increase rate of the resonant frequency bandwidth is the lowest when the first receiver and FO#4 are disposed in the charging area.

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 receiver and the type of foreign matter placed in the charging area, 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. can

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

(2111)보다 최소 공진 주파수 대역폭 변화 비율

(2121)이 2배 이상 큰 것을 알 수 있다.Referring to drawing numbers 2110 and 2120, the minimum quality factor change ratio

Minimum resonant frequency bandwidth change ratio than (2111)

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

Therefore, the foreign material detection method based on the resonant frequency bandwidth according to the present invention has the advantage of being able to more accurately detect the foreign material compared to the conventional foreign material detection method based on the quality factor value.

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

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

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

The present invention relates to wireless charging, and is particularly applicable to a wireless power transmitter equipped with a foreign matter detection function.

Claims (10)

In the wireless power transmission method of the wireless power transmission device,
measuring a resonance quality factor and a resonance frequency;
Receiving a foreign matter detection status packet including a reference resonance quality factor and a reference resonance frequency from a wireless power receiver;
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
including,
Determining whether a foreign substance exists based on the resonance frequency bandwidth and the reference resonance frequency bandwidth,
Determining the existence of a foreign substance by comparing the fluctuation rate of the resonance frequency bandwidth with a threshold rate
Wireless power transmission method comprising a. In the wireless power transmission method of the wireless power transmission device,
measuring a resonance quality factor and a resonance frequency;
Receiving a foreign matter detection status packet including a reference resonant frequency bandwidth from a wireless power receiver;
calculating a resonance frequency bandwidth based on the resonance quality factor and the resonance frequency;
Determining whether a foreign substance is present based on the resonance frequency bandwidth and the reference resonance frequency bandwidth
including,
Determining whether a foreign substance exists based on the resonance frequency bandwidth and the reference resonance frequency bandwidth,
Determining the existence of a foreign substance by comparing the fluctuation rate of the resonance frequency bandwidth with a threshold rate
Wireless power transmission method comprising a. In the wireless power transmission method of the wireless power transmission device,
measuring a resonance quality factor and a resonance frequency;
Receiving a foreign matter detection state packet including a reference resonance quality factor, a reference resonance frequency, and a reference resonance frequency bandwidth from a wireless power receiver;
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, the reference resonance frequency, and the reference resonance frequency bandwidth; and
Determining whether a foreign substance exists based on the resonance frequency bandwidth and the reference resonance frequency bandwidth
including,
Determining whether a foreign substance exists based on the resonance frequency bandwidth and the reference resonance frequency bandwidth,
Determining the existence of a foreign substance by comparing the fluctuation rate of the resonance frequency bandwidth with a threshold rate
Wireless power transmission method comprising a. According to any one of claims 1 to 3,
The resonant frequency is a frequency at which the resonator amplification ratio is maximum, and the resonant quality factor is calculated based on the resonator amplification ratio to the resonant frequency. 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. delete According to any one of claims 1 to 3,
The wireless power transmission method in which the variation ratio of the resonance frequency bandwidth is calculated by dividing a value obtained by subtracting the reference resonance frequency bandwidth from the resonance frequency bandwidth by the reference resonance frequency bandwidth. According to claim 7,
The threshold ratio is set to any one of values greater than 25% and less than 35%. According to any one of claims 1 to 3,
Determining whether a foreign substance is present by comparing the fluctuation rate of the resonant frequency bandwidth with a threshold rate,
determining that a foreign substance is present and transmitting a NACK response when the variation rate of the resonant frequency bandwidth exceeds the threshold rate; and
determining that no foreign matter exists and transmitting an ACK response when the variation ratio of the resonant frequency bandwidth is less than the threshold ratio
Wireless power transmission method comprising a. A wireless power transmitter for wirelessly transmitting power to the wireless power receiver based on the wireless power transmission method according to any one of claims 1 to 3.

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