KR20200051209A - Method and Apparatus for Detection Foreign Object - Google Patents

Abstract

The present invention relates to a foreign material detection method and a device thereof. According to an embodiment of the present invention, the foreign material detection method of a wireless power transmitter comprises the steps of: detecting a resonant frequency when an object is detected; generating a low power signal at the resonant frequency to detect a convergence voltage of a resonant tank; setting a reference voltage based on the convergence voltage; measuring a reference voltage arrival time; determining a quality factor based on the reference voltage arrival time; and determining whether there is a foreign material based on the determined quality factor.

Description

Method and device for detecting foreign substances {Method and Apparatus for Detection Foreign Object}

The present invention relates to a wireless power transmission technology, and more particularly, to a foreign matter detection method in a wireless power transmitter and an apparatus therefor.

When a non-wireless power receiver conducts a non-wireless power receiver, that is, a foreign object (FO), an electromagnetic signal transmitted from the wireless power transmitter is induced in the FO to increase the temperature. As an example, the FO may include coins, clips, pins, ballpoint pens, and the like.

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

In addition, even if there is no FO in the actual charging area, charging may be stopped when the wireless power transmitter erroneously determines that foreign matter is present in the charging area.

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

The present invention has been devised to solve the above-described problems of the prior art, and an object of the present invention is to provide a method and apparatus for detecting foreign substances during wireless charging.

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

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

The present invention can provide a wireless power transmitter and a method for detecting foreign matters.

A method for detecting a foreign object in a wireless power transmitter according to an embodiment of the present invention includes detecting a resonance frequency when an object is detected and detecting a convergence voltage of a resonance tank by generating a low power signal with the resonance frequency and the convergence voltage Based on the step of setting a reference voltage and measuring the reference voltage arrival time and determining the quality factor based on the reference voltage arrival time and determining the presence or absence of foreign matter based on the determined quality factor It can contain.

Here, the reference voltage may be set to a value between 65% and 75% of the convergence voltage.

In addition, the step of measuring the time to reach the reference voltage includes discharging power accumulated in the resonant tank, applying a low power signal using the resonant frequency to the resonant tank, and a voltage of the resonant tank to the reference voltage. It may include measuring the time it takes to reach.

Also, the low power signal may be a signal of 1 watt or less.

In addition, determining the quality factor based on the reference voltage arrival time includes calculating power supplied to the resonance tank during the reference voltage arrival time and measuring power accumulated in the resonance tank during the reference voltage arrival time. And calculating the power consumed by the resonant tank during the reference voltage arrival time by subtracting the accumulated power from the supplied power and the value obtained by dividing the consumed power from the accumulated power as a quality factor. And determining.

In addition, the step of determining the presence or absence of a foreign substance based on the quality factor is judged as the presence of a foreign substance if the quality factor is less than the reference value, and if the quality factor is greater than or equal to the reference value, it is determined that the foreign substance does not exist. It may include the steps.

In addition, when the wireless power receiver is identified after the quality factor is determined, the foreign matter detection method further includes receiving a reference quality factor value from the wireless power receiver, and the reference value can be determined based on the reference quality factor value. have.

According to another embodiment of the present invention, a method of detecting a foreign object in a wireless power transmitter includes detecting an resonance frequency when an object is detected, and discharging the power accumulated in the resonance tank when the resonance frequency is detected, and completing the discharge. If it is, generating a low power signal using the detected resonant frequency and applying it to the resonant tank, determining a quality factor based on a change in the voltage of the resonant tank over time, and based on the determined quality factor. It may include determining whether it exists.

Here, the determining of the quality factor may include determining a voltage of the resonance tank measured as a first voltage after a first time has elapsed after the application of the low power signal and a second time after application of the low power signal. Determining a voltage of the resonance tank measured as a second voltage as a second voltage, and determining a quality factor based on the first voltage and the second voltage, wherein the second time is the first It may be a time after the time.

In addition, a time before the voltage of the resonance tank reaches the convergence voltage may be set as the first time, and a time after the voltage of the resonance tank reaches the convergence voltage may be set as the second time.

In addition, the quality factor may be determined based on a value obtained by dividing the first voltage by the second voltage.

A wireless power transmitter according to another embodiment of the present invention includes an antenna including a resonant tank and a power converter that generates an AC power signal and supplies it to the antenna, and a controller that controls the operation of the power converter. When an object is sensed, a resonance frequency is detected through a frequency sweep, and a low power signal generated with the detected resonance frequency is controlled to be applied to the resonance tank to detect a convergence voltage of the resonance tank, and a reference is based on the convergence voltage. After setting the voltage, the time to reach the reference voltage is measured, and the quality factor is determined based on the time to reach the reference voltage to determine whether a foreign substance is present based on the quality factor.

Here, the controller may set the reference voltage to a value between 65% and 75% of the convergence voltage.

In addition, the controller blocks the power applied to the resonance tank to discharge the energy accumulated in the resonance tank, and then controls the low power signal to be applied to the resonance tank so that the voltage of the resonance tank reaches the reference voltage. The time taken can be measured.

Also, the low power signal may be a signal of 1 watt or less.

In addition, the controller calculates the power supplied to the resonance tank during the reference voltage arrival time, measures the power accumulated in the resonance tank during the reference voltage arrival time, and subtracts the accumulated power from the supplied power. By calculating the power consumed by the resonant tank during the reference voltage arrival time, a value obtained by dividing the power consumed by the accumulated power can be determined as a quality factor.

In addition, if the quality factor is smaller than the reference value, the controller determines that a foreign substance exists, and if the quality factor is greater than or equal to the reference value, it can be determined that the foreign substance does not exist.

In addition, when the controller identifies the wireless power receiver after determining the quality factor, the reference quality factor value may be received from the wireless power receiver, and the reference value may be determined based on the reference quality factor value.

A wireless power transmitter according to another embodiment of the present invention includes an antenna including a resonant tank and a power converter that generates and supplies an AC power signal to the antenna, and a controller that controls the operation of the power converter,

When the controller detects an object disposed in the charging area, the resonance frequency is detected through a frequency sweep, and after discharging the resonance tank, a low power signal generated at the resonance frequency is controlled to be applied to the resonance tank, and the The voltage change of the resonant tank may be measured, a quality factor may be determined based on the voltage change of the resonant tank, and the presence or absence of a foreign material may be determined based on the determined quality factor.

In addition, the controller determines the voltage of the resonant tank measured as a first voltage after the first time has elapsed after the application of the low power signal, and is measured when the second time elapses after the application of the low power signal. The voltage of the resonant tank is determined as a second voltage, and a quality factor is determined based on the value obtained by dividing the first voltage by the second voltage, but the time before the voltage of the resonant tank reaches the convergence voltage is determined by Set to 1 hour, and the time after the voltage of the resonance tank reaches the convergence voltage may be set to the second time.

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

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

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

The present invention has an advantage of providing a method and apparatus for detecting foreign matter in a wireless power transmitter.

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

In addition, the present invention has the advantage of providing a wireless power transmitter to prevent unnecessary charging interruption by minimizing foreign material detection errors.

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

1 is a block diagram illustrating a wireless charging system according to an embodiment of the present invention.
2 is a block diagram illustrating a wireless charging system according to another embodiment of the present invention.
3 is a view for explaining a detection signal transmission procedure in a wireless charging system according to an embodiment of the present invention.
4 is a state transition diagram illustrating a wireless power transmission procedure according to an embodiment of the present invention.
5 is a flowchart illustrating a foreign material detection procedure in a wireless power transmission system according to an embodiment of the present invention.
6 is a block diagram illustrating the structure of a wireless power transmission apparatus according to an embodiment of the present invention.
7 is a view for explaining the antenna configuration of FIG. 6 according to an embodiment of the present invention.
8 is a block diagram illustrating a structure of a wireless power receiving device interworking with the wireless power transmitting device according to FIG. 6 according to an embodiment of the present invention.
9 is a view for explaining a power management method of an electronic device equipped with a wireless power receiver according to an embodiment of the present invention.
10 is a view for explaining the structure of a wireless power transmitter equipped with a low power signal generator according to the present invention.
11 is a view for explaining a resonance frequency bandwidth according to an embodiment of the present invention.
12 is a view for explaining the voltage characteristics of the resonance tank provided in the wireless power transmitter according to an embodiment of the present invention.
13 is a view for explaining the power consumed in the resonant tank and the power charged while the low power signal is applied to the resonant tank according to the present invention.
14 shows power accumulated in the resonance tank in the wireless power transmitter according to the embodiment.
15 is a view for explaining a power pattern accumulated in the resonance tank for each quality factor in the radio power transmitter according to the embodiment of the present invention.
16 is a flowchart illustrating a method for detecting a foreign material in a wireless power transmitter according to an embodiment of the present invention.
17 is a flowchart illustrating a method for detecting a foreign material in a wireless power transmitter according to another embodiment of the present invention.
FIG. 18 is a view for explaining a method for detecting convergence voltage and measuring a reference voltage arrival time in the embodiment of FIG. 16.
19 is a diagram for explaining a method of determining a quality factor using a first voltage, which is a voltage measured at a first time elapsed time, and a second voltage measured at a second time elapsed time, in the embodiment of FIG. 17 described above; It is a drawing.

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

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

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

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

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

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

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

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

1 is a block diagram illustrating 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 transmitting end 10 and the wireless power receiving end 20 may perform in-band communication for exchanging information using the same frequency band as the operating frequency used for wireless power transmission.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

When an object is detected in the selection step 410, the transmitter according to an embodiment of the present invention may measure a quality factor value to determine whether a wireless power receiver is disposed with a foreign object in the charging area.

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

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

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

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

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

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

The wireless power transmitter according to another embodiment may measure the quality factor value in a predetermined frequency unit within an operating frequency band usable for wireless power transmission. In this case, the wireless power transmitter may check the operating frequency value having the maximum value among the quality factor values measured in the operating frequency band and store it in the memory. Hereinafter, for convenience of description, a frequency in which the quality factor value in the operating frequency band is maximum is referred to as a quality factor peak frequency or simply a peak frequency or a resonance frequency for convenience of description.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Is calculated as

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

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

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

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

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

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

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

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

According to another embodiment of the present invention, the transmitter may determine whether a foreign substance exists by using both a foreign substance detection method based on a quality factor peak frequency and a foreign substance detection method based on a quality factor value. For example, when there is no significant difference as a result of comparing the reference quality factor value corresponding to the transmitter type and the measured quality factor value, for example, when the difference between the two values is 10% or less, the reference quality corresponding to the transmitter type The presence or absence of foreign matter may be determined by comparing the peak frequency of the factor with the peak frequency of the measured quality factor. On the other hand, if the difference between the two quality factor values exceeds 10%, the transmitter can immediately determine that a foreign substance is present.

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

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

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

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

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

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

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

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

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

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

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

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

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

The wireless power transmitter may periodically perform a process for detecting a foreign object after entering the power transmission step 460.

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

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

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

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

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

The transmitter measures the determined quality factor threshold and / or the determined quality factor peak frequency threshold to the measured quality factor value-means the quality factor value measured before the ping step 420-and / or the measured quality factor peak frequency It is also possible to detect the foreign matter disposed in the filling area by comparing with the value.

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

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

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

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

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

In detail, when a foreign substance is not detected, the transmitter determines the strength of the power received at the receiving end when entering the correction 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 by the transmitting end. can do.

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

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

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

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

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

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

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

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

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

Referring to FIG. 5, when an object is detected in the selection step, the wireless power transmitter 510 may measure 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 step and perform the detection signal transmission procedure described in FIG. 3 above (S503).

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

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

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

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

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

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

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

Here, the power of a certain intensity or more may be 5W as a standard, but is not limited thereto. It can therefore be defined differently.

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

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

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

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

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

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

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

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

In this embodiment, the antenna 630 may be configured to include an LC resonant circuit consisting of at least one inductor (L) and at least one capacitor (Capacitor, C), that is, LC Tank-.

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

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

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

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

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

The controller 610 may generate a low power signal for quality factor measurement by controlling a burst pattern of a switch control signal applied to the inverter 621 based on the measured power. Here, the low power signal may be a power signal to which communication is not connected because the wireless power receiver is not booted.

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

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

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

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

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

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

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

8 is a block diagram illustrating a structure of a wireless power receiving device interworking with the wireless power transmitting device according to FIG. 6 according to an embodiment 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, and a modulator ( 860) and a controller 870.

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

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

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

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

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

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

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

The controller 870 may measure the output DC power strength of the rectifier 820 and control the switch 840 based on the measurement result.

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

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

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

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

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

As another example, the controller 870 may be associated with a power management element that controls the internal power of an electronic device equipped with the wireless power receiver 800-for example, a Power Management IC (PMIC) (not shown). In this case, as illustrated in FIG. 9 to be described later, the output DC power of the DC / DC converter 830 may be transferred to the PMIC 910 through the switch 840.

The PMIC 910 may control charging of the battery 920 provided in the electronic device 900 and power supply to the internal component 930 of the electronic device 900.

The PMIC 910 may provide the controller 870 with current charging state information of the battery 920. The controller 870 may determine whether charging is in progress based on current charging state information and internal temperature information of the battery 920.

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

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

9 is a view for explaining a power management method of an electronic device equipped with a wireless power receiver according to an embodiment of the present invention.

Referring to FIG. 9, the electronic device 900 may include a wireless power receiver 901, a PMIC 910, a battery 920, and internal components 930.

The detailed configuration and operation of the wireless power receiver 901 are replaced by the description of FIG. 8 described above.

The internal component 930 may include a circuit element, a microprocessor, a display, and a sensor that require a specific operating voltage, but is not limited thereto.

The wireless power receiver 901 and the PMIC 910 are electrically connected to each other through a WLC_I terminal, and the PMIC 910 may include a first switch 911 and a second switch 912.

One end of the first switch 911 may be connected to the WLC_I terminal, and the other end may be connected to one end of the internal power supply and the second switch 912.

The internal power is supplied as power required for the operation of components and elements (eg, application processor, main memory, display module, touch module, fingerprint recognition module, camera module, speaker, vibration module, etc.) provided inside the device. It means, it may further include a separate divider for distributing power to the above-described components and devices.

One end of the second switch 912 may be connected to the first switch 911 and the other end may be connected to the battery 920.

The PMIC 910 controls the first switch 911 and the second switch 912 to supply DC power received from the wireless power receiver 901 to at least one of the internal component 930 and the battery 920, or Power supplied to the internal component 930 and the battery 920 may be cut off.

For example, the first switch 911 may correspond to the switch 840 of FIG. 8 described above, and may be defined as an over voltage protection switch.

When the voltage applied from the wireless power receiver 901 exceeds a predetermined reference value, the PMIC 910 turns off the first switch 911 to damage the internal component 930 and the battery 920 by overvoltage. To prevent.

Also, the PMIC 910 may include a first switch 911 to block connection with the wireless power receiver 901 according to a request of an application processor mounted on the electronic device 900-for example, a request for disabling wireless power reception- ) Can also be turned OFF.

The second switch 912 may be defined as a battery over temperature protection switch.

For example, when the temperature of the battery 920 reaches a predetermined threshold, the PMIC 910 may turn off the second switch 912 to block charging of the battery 920.

In addition, when charging of the battery 920 is completed, the PMIC 910 may turn off the second switch 912 to block battery charging.

In FIG. 9, the battery 920 is expressed as one resistor, which is an equivalent circuit, but this is for convenience of description only. In actual implementation, the battery 920 may be implemented as a lithium-ion battery or the like.

10 is a view for explaining the structure of a wireless power transmitter equipped with a low power signal generator according to an embodiment of the present invention.

As shown in FIG. 10, the wireless power transmitter 1000 includes a low power signal generator 1010, an AC amplifying circuit 1020, a peak detector 1030, an attenuator or DC remover 1040, and a controller 1050. It was composed. For convenience of description below, the attenuator or DC remover 1040 will be briefly described as the attenuator 1040.

The AC amplifying circuit 1020 includes first to fourth switches 1021 to 1024 and a resonance tank circuit 1025. For convenience of description below, the resonance tank circuit will be used in combination with a resonance tank, a resonance circuit, and the like.

The first to fourth switches 1021 to 1024 and the resonance tank circuit 1025 constituting the AC amplifying circuit 1020 may correspond to the inverter 621 and the antenna 630 of FIG. 6 described above, respectively. That is, the antenna 630 includes a resonant tank composed of an inductor and a capacitor connected in series, and the inverter 621 may include first to fourth switches 1021 to 1024 for generating an AC power signal. .

The first to fourth switches 1021 to 1024 provided in the AC amplifying circuit 1020 may be driven based on the first to fourth switch control signals SC_1 to SC_4 and 1051 applied from the controller 1050. .

The first to fourth switches 1021 to 1024 are arranged in a full-bridge form, and the resonance tank circuit 1025 may include a capacitor C1 connected in series and an inductor L1. .

The low power signal generator 1010 may include a fifth switch 1011, a sixth switch 1012, and resistance elements R1 and 1013.

The fifth switch 1011 and the sixth switch 1012 of the low power signal generator 1010 are driven based on the fifth to sixth switch control signals SC_5 to SC_6, 1052 applied from the controller 1050, It may be arranged in a half-bridge (Half-Bridge) form. Here, resistor elements R1 and 1013 are connected between the fifth switch 1011 and the sixth switch 1012.

Here, the resistance element 1013 may drop the voltage V3 of the signals generated by the fifth switch 1011 and the sixth switch 1012 to the voltage V1 and transfer the voltage V3 to the resonance tank circuit 1025.

The controller 1050 may provide the fifth switch control signal SC_5 and the sixth switch control signal SC_6, which are pulse width modulated such that the duty is 50% and the phase is 180 degrees different, to the low power signal generator 1010. .

When an object is detected in the charging area, the controller 1050 may control the low power signal generator 1010 to generate a low power signal before entering the ping phase.

At this time, the controller 1050 is the first so that only the fourth switch 1024 of the switches provided in the AC amplifying circuit 1020 is ON and the other switches, that is, the first to third switches 1021 to 1023 are OFF. The fourth to fourth switch control signals SC_1 to SC_4 and 1051 may be controlled. For example, if the switch control signal is a HIGH signal, it is switched on, and if it is a LOW signal, it can be switched off.

The peak detector 1030 may detect a peak of a signal flowing between the capacitor C1 of the resonant tank circuit 1025 and the inductor L1, and transmit the peak detection signal to the attenuator or DC remover 1040.

The attenuator or DC remover 1040 may attenuate the intensity of the peak detection signal to a level required by the controller 1050 or remove the DC component and transmit it to the controller 1050.

The controller 1050 may control the low power signal generator 1010 to control the output of the low power signal through the AC amplifying circuit 1020. For example, the intensity of the low power signal may be controlled to 1 watt (W) or less.

The controller 1050 may search for a frequency having a maximum peak-to-peak voltage or current by sweeping a frequency in an operating frequency band during outputting a low power signal, and determine the found frequency as a resonance frequency.

In addition, the controller 1050 may measure the converging voltage of the resonance tank using the searched resonance frequency. The controller 1050 may determine the convergence voltage of the resonance tank based on the voltage of the signal applied from the attenuator 1140. Here, the convergence voltage of the resonant tank means a voltage that converges constantly without increasing the voltage any more because the energy is almost completely accumulated in the resonant tank, as shown in FIG. 12 to be described later.

Therefore, the controller 1050 may determine the corresponding voltage level as a converging voltage when energy stored in the resonance tank is almost saturated during low power signal transmission and the voltage is maintained within a predetermined error range.

When the convergence voltage corresponding to the resonant frequency is determined, the controller 1050 may temporarily control the output of the low power signal so that all energy stored in the resonant tank is discharged.

For example, the controller 1050 may determine that all energy stored in the resonance tank is discharged when the voltage level of the signal input to the attenuator 1140 no longer drops and is maintained at a constant level.

When all of the energy stored in the resonance tank is discharged, the controller 1050 may control the output of the low power signal using the resonance frequency to start again.

The controller 1050 may measure the time taken until the voltage of the completely discharged resonant tank reaches a certain level after resuming the output of the low power signal. Here, the specific level may be determined by a certain ratio of the saturation voltage of the resonance tank. For example, a certain ratio may be determined as a value between 65% and 75%, but is not limited thereto.

For convenience of the following description, the time required for the voltage of the resonant tank to reach a certain level after discharge will be referred to as "reference voltage arrival time".

The controller 1050 may determine a quality factor corresponding to the measured reference voltage arrival time.

For example, the controller 1050 may calculate the supply power a of the resonance tank during the measured reference voltage arrival time. For example, when a low power of 1 watt (W) per second is supplied and the measured reference voltage arrival time is 5 seconds, the supply power a may be calculated as 5 W.

Further, the controller 1050 may measure the power b stored in the measured reference voltage arrival time resonance tank.

The controller 1050 may calculate power c consumed by the resonance tank by subtracting power b stored in the resonance tank from the supply power a.

At this time, the quality factor Q may be determined as b / c.

As another example, the quality factor corresponding to the reference level arrival time may be pre-stored in a memory (not shown) provided in the wireless power transmitter 1000 after being configured in the form of a table.

The controller 1050 may determine whether a foreign material is present based on the determined quality factor.

For example, if the determined quality factor is smaller than a predetermined threshold, the controller 1050 may determine that a foreign substance exists in the filling area. On the other hand, if the determined quality factor is greater than or equal to a predetermined threshold, the controller 1050 may determine that there is no foreign substance in the filling area. Here, the threshold may be determined based on the reference quality factor value included in the foreign matter detection status packet received in the negotiation step 440.

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

1100 is a graph showing a relationship between a bandwidth and a resonance frequency in a resonance circuit of a wireless charging system.

(1112)에서 피크 투 피크 전압의 진폭 또는 전압/전류의 진폭이 최대인 것을 알 수 있다.11, the resonance frequency

It can be seen from (1112) that the amplitude of the peak-to-peak voltage or the amplitude of the voltage / current is the maximum.

로부터 3dB 아래인 전압 또는 전류를 가지는 2개의 동작 주파수 또는 하프 파워 대역폭 주파수가 존재할 수 있다. 이하 설명의 편의를 위해 최대 진폭(1111)으로부터 3dB 아래인 2개의 동작 주파수를 각각 하한 대역폭 주파수(

, 1113) 및 상한 대역폭 주파수(

, 1114)로 명하기로 한다. 여기서, 3dB 아래인 진폭은 최대 진폭(1111)의 약 70.7%일 수 있다.Amplitude with maximum value

There may be two operating frequencies or half power bandwidth frequencies with voltage or current below 3 dB from. For convenience of explanation below, the two operating frequencies, which are 3 dB below the maximum amplitude (1111), are each lower bandwidth frequencies (

, 1113) and the upper bandwidth frequency (

, 1114). Here, the amplitude below 3dB may be about 70.7% of the maximum amplitude 1111.

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 the power transmission efficiency (or transmission power) is reduced in half.

- 으로 정의될 수 있다.The resonant frequency bandwidth 1115 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 above-described embodiment of FIG. 11, it is described that the resonant frequency bandwidth 1115 is determined by frequencies having a voltage or a current that is 3 dB below the maximum amplitude 1111, but this is only one embodiment, and the maximum A frequency region having a voltage or current of xdB lower than 3dB from the amplitude 1111 may be defined as the resonance frequency bandwidth 1115. Here, it should be noted that the x value may be set differently according to the design purpose of the skilled person 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 a resonant frequency (

) And corresponding resonance frequency

Quality factor values at

It 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 Equation 2 below.

<수학식 2>

<Equation 2>

은 하한 대역폭 주파수이고

는 상한 대역폭 주파수이다.here,

Is the lower bandwidth frequency

Is the upper bandwidth frequency.

12 is a view for explaining the voltage characteristics of the resonance tank provided in the wireless power transmitter according to an embodiment of the present invention.

Referring to FIG. 12, when power is applied to the resonance tank in a state where the voltage of the resonance tank is a discharge voltage 1230-that is, the voltage of the resonance tank is 0V, the voltage of the resonance tank is the time It increases over time and then converges to a certain level.

Here, converging the voltage of the resonant tank to a constant level means that the energy charged in the resonant tank has almost reached the saturation state.

Hereinafter, for convenience of description, a voltage corresponding to a state in which the energy of the resonant tank has almost reached the saturation state will be referred to as a “convergence voltage 1230”.

Here, it should be noted that the convergence voltage 1230 is not a voltage measured when the resonance tank is fully charged with energy and saturated.

The wireless power transmitter may determine a voltage corresponding to a predetermined ratio of the convergence voltage 1230 as the reference voltage 1220.

Here, the reference voltage 1220 is a voltage lower than the convergence voltage 1230.

In an embodiment, the reference voltage 1220 may be determined at a level of 70% of the convergence voltage 1230, but is not limited thereto, and the reference voltage is selected as one of the ratios between 65% and 75% of the convergence voltage 1230 Can be.

The wireless power transmitter may calculate a time required for the voltage of the resonant tank in the discharged state to reach the reference voltage 1220 during the output of the low power signal.

For convenience of description below, the time taken until the reference voltage 1220 is reached after the low power signal of the resonance frequency is applied to the resonance tank in the state where the voltage of the resonance tank is the discharge voltage 1240 is the reference voltage arrival time ( 1240).

The wireless power transmitter may estimate or determine a quality factor based on the reference voltage arrival time 1240. In general, the higher the quality factor, the longer the reference voltage arrival time 1240 increases.

As shown in FIG. 12, the closer to the convergence voltage 1230, there is little change in voltage with time, so it is difficult to accurately measure the time when the convergence voltage 1230 is reached.

Therefore, the reason why the wireless power transmitter according to the present embodiment determines or estimates the quality factor based on the reference voltage 1220 rather than the convergence voltage 1230 is that the reference voltage 1220 is on a section in which a voltage change with time is obvious. This is because there is an advantage in that the time to reach the reference voltage 1240 can be more clearly measured.

In addition, the wireless power transmitter according to the present embodiment has an advantage of determining or estimating the quality factor more quickly by measuring the time to reach the reference voltage 1220 rather than the convergence voltage 1230.

13 is a view for explaining the power consumed in the resonance tank and the power charged while the low power signal is applied to the resonance tank according to the present invention.

In detail, FIG. 13 is a view for explaining changes in power consumption and charging power in a resonance tank over time when the quality factor is 9.

The quality factor may be calculated by dividing the power stored in the resonant tank for a predetermined time by the power consumed in the resonant tank during the corresponding time. The resonant tank generates power consumption due to its own resistance component.

Referring to FIG. 13, when the supply power during the first period is 1, power consumed during the first period in the resonance tank of the wireless power transmitter having a quality factor of 9 is 0.1, and power accumulated in the resonance tank is 0.9.

When the power supplied during the second cycle is 1, the power consumed during the second cycle is 0.19, which is 10% of the sum of the power accumulated in the first cycle 0.9 and the power 1 supplied during the second cycle, and the resonant tank during the second cycle. The power accumulated at is 1.71, which is 90% of the sum of the power accumulated during the first cycle and the power 1 supplied during the second cycle.

When the supply power during the third cycle is 1, the power consumed during the third cycle is 10% of the sum of the power accumulated during the first cycle 0.9, the power accumulated during the second cycle 1.71, and the power 1 supplied during the third cycle. Phosphorus is 0.271, and the power accumulated in the resonant tank during the third cycle is 2.439, which is 90% of the sum of the power 1.71 accumulated during the second cycle and the power 1 supplied during the third cycle.

일때, N번째 주기에 공진 탱크에 축적된 전력

은 하기의 수식:In other words, the quality factor

Power, accumulated in the resonant tank in the Nth cycle

Is the following formula:

Can be calculated as

14 shows power accumulated in the resonance tank in the wireless power transmitter according to the embodiment.

In detail, FIG. 14 shows power accumulated in the resonance tank in the wireless power transmitter having a quality factor of 10.

14, when the energy stored in the resonance tank is completely discharged and power is supplied, the voltage of the resonance tank converges when the first time 1412 elapses.

That is, when the first time 1412 elapses after starting power supply to the resonance tank, the voltage of the resonance tank reaches the convergence voltage 1411. At this time, the first time 1412, which is the time required to reach the converging voltage 1411 in the discharge state, is proportional to the quality factor.

In other words, the larger the quality factor, the more time it takes to reach the convergence state.

14, the wireless power transmitter may set a voltage that is a predetermined ratio of convergence voltage 1411-for example, 70%-as reference voltage 1421.

When the energy stored in the resonance tank is completely discharged and power is supplied again, the voltage of the resonance tank reaches the reference voltage 1412 after the second time 1422 elapses.

The wireless power transmitter according to the present embodiment may measure the second time 1421 and determine or estimate a quality factor based on the measured second time 1421.

The wireless power transmitter may compare the estimated quality factor with a predetermined threshold to determine the presence of foreign matter.

15 is a view for explaining a power pattern accumulated in the resonance tank for each quality factor in the radio power transmitter according to the embodiment of the present invention.

15, reference number 1510 is a graph showing power change accumulated in a resonant tank over time when the quality factor is 10, that is, a voltage change in the resonant tank, and reference number 1520 has a quality factor of 20 days. At this time, it is a graph showing the power change accumulated in the resonant tank over time, and reference number 1530 is a graph showing the power change accumulated in the resonant tank over time when the quality factor is 30.

Referring to FIG. 1510, when the quality factor is 10, it is shown that the time required for the voltage of the resonance tank to reach the reference voltage 1511 in the discharge state is 13 cycles.

Referring to FIG. 1520, when the quality factor is 20, it is shown that the time required for the voltage of the resonance tank to reach the reference voltage 1521 in the discharge state is 25 cycles.

Referring to FIG. 1530, when the quality factor is 30, it is shown that the time required for the voltage of the resonant tank to reach the reference voltage 1531 in the discharged state is 37 cycles.

As shown in FIG. 15, it can be seen that as the quality factor is increased, the time required to reach the reference voltage in the discharged state increases.

16 is a flowchart illustrating a method for detecting a foreign material in a wireless power transmitter according to an embodiment of the present invention.

Referring to FIG. 16, when an object is detected, the wireless power transmitter may search for a resonance frequency through a frequency sweep in an operating frequency band (S1610 to S1620).

The wireless power transmitter may generate and apply a low power signal to the resonance tank at the resonant frequency (S1630).

The wireless power transmitter may detect the convergence voltage of the resonant tank (S1640).

The wireless power transmitter may set the reference voltage based on the convergence voltage (S1650). Here, the reference voltage may be set lower than the convergence voltage. For example, the reference voltage may be set to 70% of the convergence voltage, but is not limited thereto. As another example, the reference voltage may be set to any one value between 65% and 75% of the convergence voltage.

The wireless power transmitter temporarily measures the time at which the voltage of the resonance tank reaches the reference voltage by temporarily shutting off the supply of power to the resonance tank to completely discharge the resonance tank and then applying a low power signal to the resonance tank again (S1660).

The wireless power transmitter may estimate (or calculate or determine) a quality factor based on the measured reference voltage arrival time (S1670).

For example, the wireless power transmitter may calculate the supply power applied to the resonance tank during the reference voltage arrival time and measure the power accumulated in the resonance tank during the reference voltage arrival time. Thereafter, the wireless power transmitter may calculate power consumed in the resonance tank during a reference voltage arrival time by subtracting the accumulated power from the calculated supply power. The wireless power transmitter may estimate (or determine or calculate) a quality factor by dividing the power accumulated in the resonance tank during the reference voltage arrival time by the power consumed.

The wireless power transmitter may determine the presence or absence of a foreign object based on the determined or estimated quality factor (S1680).

For example, if the determined or estimated quality factor is less than the reference value, the wireless power transmitter may determine that a foreign substance exists, and if the determined or estimated quality factor is greater than or equal to the reference value, the foreign substance does not exist. . Here, the reference value may be determined based on the reference quality factor value of the foreign matter detection status packet received from the wireless power receiver in the negotiation step 440.

17 is a flowchart illustrating a method for detecting a foreign material in a wireless power transmitter according to another embodiment of the present invention.

Referring to FIG. 17, when an object is detected, the wireless power transmitter may search for a resonance frequency through a frequency sweep in an operating frequency band (S1710 to S1720).

When the resonant frequency search is completed, the wireless power transmitter may cut off power applied to the resonant tank to discharge the energy accumulated in the resonant tank (S1730).

When the resonant tank is completely discharged, the wireless power transmitter may generate a low power signal with the searched resonant frequency and apply it to the resonant tank (S1740).

The wireless power transmitter may measure the voltage of the resonant tank at the time when the first time elapses after the low power signal is applied (S1750). Here, the voltage measured when the first time elapses after the application of the low power signal is referred to as the first voltage.

The wireless power transmitter may measure the voltage of the resonant tank when the second time elapses after the low power signal is applied (S1760). Here, the voltage measured at the time when the second time elapses after the application of the low power signal is referred to as the second voltage. Here, the second time is a time after the first time.

For example, the first time may be 0.4ms and the second time may be 10ms, but is not limited thereto, and the first time and the second time may be set differently according to the design of a person skilled in the art.

The wireless power transmitter may determine or determine or estimate a quality factor based on the first voltage and the second voltage (1770).

For example, the wireless power transmitter may determine or estimate the quality factor based on the value obtained by dividing the first voltage by the second voltage. Here, as the value obtained by dividing the first voltage by the second voltage decreases, the quality factor increases, and as the value divided by the first voltage increases, the quality factor decreases.

The wireless power transmitter may determine whether a foreign object is present based on the determined or estimated quality factor (S1780).

For example, if the estimated quality factor is less than the reference value, the wireless power transmitter may determine that a foreign substance exists, and if the estimated quality factor is greater than or equal to the reference value, it may be determined that the foreign substance does not exist. Here, the reference value may be determined based on the reference quality factor value of the foreign matter detection status packet received from the wireless power receiver in the negotiation step 440.

18 is a view for explaining a method of measuring convergence voltage and measuring a time to reach a reference voltage in the embodiment of FIG. 16 described above.

Referring to FIG. 18, when power is applied to the resonance tank (S1801), energy starts to accumulate in the resonance tank, and accordingly, the voltage of the resonance tank increases over time (S1802). When the energy accumulated in the resonant tank reaches an almost saturated state, the voltage of the resonant tank converges while being maintained at a substantially constant level (S1803). At this time, the wireless power transmitter may determine a voltage maintained at a constant level as a converging voltage (S1804).

The wireless power transmitter may set the reference voltage based on the determined convergence voltage (S1805).

When the convergence voltage is determined, the wireless power transmitter cuts power applied to the resonance tank to discharge the energy accumulated in the resonance tank (S1806).

When the resonant tank is completely discharged, the wireless power transmitter may apply power to the resonant tank again (S1807).

After the power is applied, the wireless power transmitter may measure the time taken until the voltage of the resonance tank reaches the reference voltage (S1808).

Thereafter, the wireless power transmitter may determine or estimate the quality factor based on the measured reference voltage arrival time.

19 illustrates a method of determining or estimating a quality factor using the first voltage, which is the voltage measured at the first time elapsed, and the second voltage measured at the second time elapsed, in the embodiment of FIG. 17 described above. It is a drawing for doing.

As shown in FIG. 19, the first time is before the second time, and the first voltage is always lower than the second voltage.

The wireless power transmitter may determine or estimate the quality factor based on the ratio of the first voltage and the second voltage.

As described above, the wireless power transmission apparatus according to the present invention has an advantage of detecting foreign substances more accurately, thereby preventing heat and power loss due to foreign substances from being prevented and preventing damage to devices due to heat generation. .

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

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

Claims (20)

Detecting a resonance frequency;
Generating a low power signal at the resonant frequency to detect a converging voltage of the resonant tank;
Setting a reference voltage based on the converging voltage;
Measuring a reference voltage arrival time;
Determining a quality factor based on the reference voltage arrival time; And
Determining whether a foreign substance is present based on the quality factor
Foreign matter detection method of a wireless power transmitter comprising a. According to claim 1,
The reference voltage is set to a value between 65% and 75% of the convergence voltage. According to claim 1,
The step of measuring the time to reach the reference voltage is
Discharging the electric power accumulated in the resonance tank;
Applying a low power signal using the resonance frequency to the resonance tank; And
Measuring a time required for the voltage of the resonance tank to reach the reference voltage
Foreign matter detection method of a wireless power transmitter comprising a. According to claim 3,
The low power signal is a method of detecting a foreign object in a wireless power transmitter that is a signal of 1 watt or less. According to claim 1,
Determining the quality factor based on the reference voltage arrival time,
Calculating power supplied to the resonance tank during the reference voltage arrival time;
Measuring the power accumulated in the resonance tank during the reference voltage arrival time;
Subtracting the accumulated power from the supplied power to calculate power consumed by the resonant tank during the reference voltage arrival time; And
Estimating a value obtained by dividing the consumed power from the accumulated power as a quality factor
Foreign matter detection method of a wireless power transmitter comprising a. The method according to any one of claims 1 to 5,
The step of determining the presence of a foreign material based on the quality factor
If the quality factor is smaller than the reference value, determining that foreign matter is present; And
If the quality factor is greater than or equal to the reference value, determining that no foreign substance exists
Foreign matter detection method of a wireless power transmitter comprising a. The method of claim 6,
If the wireless power receiver is identified after the quality factor is determined, further comprising receiving a reference quality factor value from the wireless power receiver, and detecting a foreign matter in the wireless power transmitter on which the reference value is determined based on the reference quality factor value. . Detecting a resonance frequency;
Discharging the electric power accumulated in the resonance tank when the resonance frequency is detected;
When the discharge is completed, generating a low power signal using the detected resonance frequency and applying it to the resonance tank;
Determining a quality factor based on a change in voltage of the resonant tank over time; And
Determining whether a foreign substance is present based on the determined quality factor
Foreign matter detection method of a wireless power transmitter comprising a. The method of claim 8,
Determining the quality factor is
Determining a voltage of the resonance tank measured as a first voltage after a first time has elapsed after the application of the low power signal;
Determining a voltage of the resonance tank measured as a second voltage after a second time has elapsed after the application of the low power signal;
Determining a quality factor based on the first voltage and the second voltage
Including, The second time is a time after the first time The foreign matter detection method of the wireless power transmitter. The method of claim 9,
Foreign material detection of a wireless power transmitter that sets the time before the voltage of the resonance tank reaches the convergence voltage to the first time and sets the time after the voltage of the resonance tank reaches the convergence voltage to the second time Way. The method of claim 9 or 10,
A method of detecting a foreign material in a wireless power transmitter that determines the quality factor based on a value obtained by dividing the first voltage by the second voltage. An antenna including a resonant tank;
A power converter that generates an AC power signal and supplies it to the antenna; And
Controller for controlling the operation of the power converter
Including,
When the controller detects an object, a resonance frequency is detected through a frequency sweep, and a low power signal generated with the detected resonance frequency is controlled to be applied to the resonance tank to detect a convergence voltage of the resonance tank, and to the convergence voltage. A wireless power transmitter that measures a reference voltage arrival time after setting a reference voltage based thereon, determines a quality factor based on the reference voltage arrival time, and determines whether a foreign substance is present based on the determined quality factor. The method of claim 12,
A wireless power transmitter wherein the controller sets the reference voltage to a value between 65% and 75% of the convergence voltage. The method of claim 12,
The controller
The power applied to the resonance tank is cut to discharge the energy accumulated in the resonance tank, and then the low-power signal is controlled to be applied to the resonance tank to measure the time required for the voltage of the resonance tank to reach the reference voltage. Wireless power transmitter. The method of claim 14,
The low power signal is a wireless power transmitter that is a signal of 1 watt (W) or less. The method of claim 12,
The controller calculates the power supplied to the resonant tank during the reference voltage arrival time, measures the power accumulated in the resonant tank during the reference voltage arrival time, subtracts the accumulated power from the supplied power, and A wireless power transmitter for calculating power consumed by the resonance tank during a reference voltage arrival time and determining a value obtained by dividing the power consumed by the accumulated power as a quality factor. The method according to any one of claims 12 to 16,
The controller
If the quality factor is smaller than the reference value, it is determined that a foreign substance exists, and if the quality factor is greater than or equal to the reference value, the wireless power transmitter determines that the foreign substance does not exist. The method of claim 17,
When the controller identifies the wireless power receiver after estimating the quality factor, a wireless power transmitter that receives a reference quality factor value from the wireless power receiver and determines the reference value based on the reference quality factor value. An antenna including a resonant tank;
A power converter that generates an AC power signal and supplies it to the antenna; And
Controller for controlling the operation of the power converter
Including,
The controller
When an object disposed in the charging area is sensed, a resonance frequency is detected through a frequency sweep, and after discharging the resonance tank, a low power signal generated at the resonance frequency is controlled to be applied to the resonance tank, thereby controlling the resonance tank over time. A wireless power transmitter that measures a voltage change, determines a quality factor based on the voltage change of the resonance tank, and determines whether a foreign object is present based on the determined quality factor. The method of claim 19,
The controller
The voltage of the resonant tank measured at the first time after the application of the low power signal is determined as a first voltage, and the voltage of the resonant tank measured at the second time after the application of the low power signal has passed. Is determined as a second voltage, and a quality factor is determined based on a value obtained by dividing the first voltage by the second voltage.
A wireless power transmitter that sets a time before the voltage of the resonance tank reaches the convergence voltage as the first time, and sets a time after the voltage of the resonance tank reaches the convergence voltage as the second time.

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