KR101750870B1 - Wireless power transfer method, apparatus and system - Google Patents

Abstract

The present invention relates to a wireless power transmission method, a wireless power transmission apparatus, and a wireless charging system in a wireless power transmission field, and more particularly, to an external object detection method of a wireless power transmission apparatus configured to transmit power wirelessly to a wireless power reception apparatus A frequency characteristic of a current flowing in a coil in the wireless power transmission apparatus for a predetermined time is obtained, a peak frequency corresponding to a peak value is detected using the obtained frequency characteristic, And comparing the resonance frequency of the external object with the resonance frequency of the external object.

Description

[0001] WIRELESS POWER TRANSFER METHOD, APPARATUS AND SYSTEM [0002] BACKGROUND OF THE INVENTION [0003]

The present invention relates to a wireless power transmission method, a wireless power transmission device and a wireless charging system in the field of wireless power transmission.

[0002] Instead of a method of supplying electrical energy to a wireless power receiving apparatus by wire, a method of wirelessly supplying electric energy without contact has been used. A wireless power receiving apparatus that receives energy wirelessly may be driven directly by the received wireless power, or may be powered by the charged power by charging the battery using the received wireless power.

In order to transmit smooth wireless power between the wireless power transmission apparatus for transmitting the wireless power and the wireless power reception apparatus for receiving wireless power, standardization (i.e., standardization) of technology related to transmission of wireless power is underway.

As part of the standardization of the technology relating to the transmission of the above-mentioned wireless power, the Wireless Power Consortium, which deals with the technology for the wireless power transmission of the self-induction type, announced on April 12, 2010 that the interoperability "1. Description, Version 1.00 Release Candidate 1, Interface Definition, Version 1.00 RC1 (System Description Wireless Power Transfer, Volume 1, Low Power, Part 1: Low Power, Part 1: "We released the standard document.

Meanwhile, Power Matters Alliance, another technical standards body, was established in March 2012 to develop a family of interface standards and to release standard documents based on inductive coupling technology to provide inductive resonant power. Respectively.

 The wireless charging method using electromagnetic induction as described above is already frequently encountered in our lives. For example, electric toothbrushes, wireless coffee pots, and the like.

On the other hand, when an external object other than the receiving apparatus is placed in a wireless power transmission apparatus configured to transmit power wirelessly to a wireless power receiving apparatus, it is necessary to determine that an external object is placed before the power is transmitted .

Accordingly, the present invention provides a method of detecting an external object in a wireless power transmission apparatus that is configured to wirelessly transmit power to a wireless power receiving apparatus.

An object of the present invention is to provide a method by which a transmission apparatus can determine that an external object is placed before transmitting power when an external object is placed in the wireless power transmission apparatus, not the reception apparatus.

A method for detecting an external object in a wireless power transmission apparatus configured to transmit power wirelessly to a wireless power receiving apparatus, the method comprising: obtaining a frequency characteristic of a current flowing in a coil in the wireless power transmission apparatus for a predetermined period of time; Detecting a peak frequency corresponding to a peak value and comparing the peak frequency with a resonant frequency of the wireless power transmission apparatus using the characteristic and detecting whether the external object is placed in the transmission apparatus .

In one embodiment, prior to the step of acquiring the frequency characteristic of the current, transmitting an analog ping signal to the receiving device, and if the current flowing in the coil is above a first threshold value, It is determined that there is no set-up data.

In one embodiment, the step of comparing the first frequency and the resonance frequency may include the steps of: determining whether the peak value of the current is equal to or less than a second threshold value; and comparing the difference between the peak frequency and the resonance frequency, And judging that the external object is placed when the frequency is equal to or higher than a threshold frequency which is an error range of frequency for judging that the external object is placed.

In one embodiment, the method further comprises transmitting a digital ping signal to the receiving device after detecting whether the external object has been placed.

In one embodiment, the current flowing through the coil is generated by pulse width modulation (PWM) applied to an inverter in the transmitter.

In one embodiment, the pulse width modulation (PWM) signal is generated during a reference time, and the reference time is shorter than the predetermined time.

Accordingly, the present invention can detect that an external object is placed in a wireless power transmission apparatus that is configured to wirelessly transmit power to a wireless power receiving apparatus.

FIG. 1 is an exemplary view conceptually showing a wireless power transmission apparatus and a wireless power reception apparatus according to embodiments of the present invention.
2A and 2B are block diagrams illustrating exemplary configurations of a wireless power transmission device and a wireless power reception device that can be employed in the embodiments disclosed herein.
3 illustrates a concept that power is transmitted from a wireless power transmission apparatus to a wireless power receiving apparatus wirelessly according to an inductive coupling scheme.
4A and 4B are block diagrams illustrating a portion of a configuration of a wireless power transmission apparatus and a wireless power reception apparatus of a magnetic induction type that can be employed in the embodiments disclosed herein.
5 is a block diagram of a wireless power transmission apparatus configured to have one or more transmission coils that receive power in accordance with an inductive coupling scheme employable in the embodiments disclosed herein.
FIG. 6 illustrates a concept that power is transmitted from a wireless power transmission apparatus to a wireless power reception apparatus wirelessly according to a resonant coupling scheme.
7A and 7B are block diagrams exemplarily showing a part of a configuration of a wireless power transmission apparatus and a wireless power reception apparatus of a resonance type usable in the embodiments disclosed herein.
8 is a block diagram of a wireless power transmission apparatus configured to have one or more transmission coils that receive power in accordance with a resonant coupling scheme employable in the embodiments disclosed herein.
9 illustrates a concept of transmitting and receiving packets between a wireless power transmission device and an electronic device through modulation and demodulation of a wireless power signal in wireless power transmission according to the embodiments disclosed herein.
10 illustrates a configuration for transmitting and receiving a power control message in a wireless power transmission according to the embodiments disclosed herein.
11A, 11B, and 11C illustrate the form of signals in modulation and demodulation performed in a wireless power transmission in accordance with the embodiments disclosed herein.
12A, 12B and 12C illustrate a packet including a power control message used in a wireless power transfer method according to the embodiments disclosed herein.
13 illustrates operating states of a wireless power transmission apparatus and a wireless power receiving apparatus according to embodiments disclosed herein.
14 to 18 show the structure of packets including power control messages between the wireless power transmission apparatus and the wireless power reception apparatus.
19 is a conceptual diagram showing a method by which a wireless power transmission apparatus transmits electric power to one or more wireless power reception apparatuses.
20 is a circuit diagram exemplarily showing a part of the configuration of a radio-frequency power transmission apparatus of a magnetic induction type that can be employed in the embodiments disclosed in this specification.
21 and 22 are flowcharts showing a method of detecting an external object of a wireless power transmission apparatus of a magnetic induction type that can be employed in the embodiments disclosed herein.
23A and 23B show time characteristics and frequency characteristics of the current in the transmission coil of the wireless power transmission apparatus according to the present invention, respectively.
24A and 24B show the frequency characteristics of the current in the transmission coil of the wireless power transmission apparatus for the low power reception apparatus and the medium power reception apparatus.

The techniques disclosed herein apply to wireless power transmission. However, the technology disclosed in this specification is not limited thereto, and can be applied to all power transmission systems and methods, wireless charging circuits and methods, and other methods and apparatus that utilize wirelessly transmitted power to which the technical idea of the technology can be applied .

It is noted that the technical terms used herein are used only to describe specific embodiments and are not intended to limit the invention. It is also to be understood that the technical terms used herein are to be interpreted in a sense generally understood by a person skilled in the art to which the present invention belongs, Should not be construed to mean, or be interpreted in an excessively reduced sense. Further, when a technical term used herein is an erroneous technical term that does not accurately express the spirit of the present invention, it should be understood that technical terms that can be understood by a person skilled in the art are replaced. In addition, the general terms used in the present invention should be interpreted according to a predefined or prior context, and should not be construed as being excessively reduced.

Also, the singular forms "as used herein include plural referents unless the context clearly dictates otherwise. In the present application, the term "comprising" or "comprising" or the like should not be construed as necessarily including the various elements or steps described in the specification, Or may be further comprised of additional components or steps.

Furthermore, suffixes "module" and " part "for components used in the present specification are given or mixed in consideration of ease of specification, and do not have their own meaning or role.

Furthermore, terms including ordinals such as first, second, etc. used in this specification can be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals refer to like or similar elements throughout the several views, and redundant description thereof will be omitted.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. It is to be noted that the accompanying drawings are only for the purpose of facilitating understanding of the present invention, and should not be construed as limiting the scope of the present invention with reference to the accompanying drawings.

Justice

Many-to-one communication method: how one transmitter (Tx) communicates with multiple receivers (Rx)

Unidirectional communication: a communication method in which a receiver only sends a necessary message to the transmitter side

Bidirectional communication: A transmitter is a receiver and a receiver is a transmitter, that is, a communication method capable of transmitting messages on both sides

Here, the transmitter and the receiver are the same as the transmitter and the receiver, respectively, and these terms can be used in combination.

Wireless power transmission device and wireless power receiving device conceptual diagram

FIG. 1 is an exemplary view conceptually showing a wireless power transmission apparatus and a wireless power reception apparatus according to embodiments of the present invention.

1, the wireless power transmission apparatus may be a power transmission apparatus that transmits power wirelessly required by the wireless power receiving apparatus 200. [

The wireless power transmission apparatus may be a wireless charging apparatus that charges the battery of the wireless power receiving apparatus 200 by transmitting power wirelessly.

In addition, the wireless power transmission apparatus may be implemented as various types of apparatuses that transmit power to the wireless power receiving apparatus 200 that requires power in a non-contact state.

The wireless power receiving apparatus 200 is a device capable of operating by receiving power wirelessly from the wireless power transmission apparatus. Also, the wireless power receiving apparatus 200 can charge the battery using the received wireless power.

Meanwhile, the wireless power receiving apparatus that receives power wirelessly as described in the present specification may be any portable electronic apparatus such as a keyboard, a mouse, an auxiliary output device such as a video or audio auxiliary output device, a cellular phone, a cellular phone, A smart phone, a PDA (Personal Digital Assistants), a PMP (Portable Multimedia Player), a tablet, or a multimedia device.

The wireless power receiving apparatus 200 may be a mobile communication terminal (e.g., a cellular phone, a cellular phone, a tablet) or a multimedia device, as described later.

Meanwhile, the wireless power transmission apparatus can transmit power wirelessly to the wireless power receiving apparatus 200 without mutual contact using one or more wireless power transmission methods. That is, the wireless power transmission apparatus uses an inductive coupling based on a magnetic induction phenomenon by the wireless power signal and a magnetic resonance coupling based on an electromagnetic resonance phenomenon by a wireless power signal of a specific frequency More than one can be used to deliver power.

The inductive coupling type wireless power transmission is a technique of wirelessly transmitting power by using a primary coil and a secondary coil, and a current is induced to the other coil through a magnetic field changing in one coil due to the magnetic induction phenomenon, .

In the wireless power transmission by the resonance coupling method, resonance occurs in the wireless power receiving apparatus 200 due to a wireless power signal transmitted from the wireless power transmission apparatus, And power is transmitted to the power receiving apparatus 200.

Hereinafter, embodiments of the wireless power transmission apparatus and wireless power receiving apparatus 200 disclosed in the present specification will be described in detail. In the drawings, the same reference numerals as possible are used to denote the same or similar components, even if they are shown in different drawings.

2A and 2B are block diagrams illustrating exemplary configurations of a wireless power transmission apparatus and a wireless power reception apparatus 200 that can be employed in the embodiments disclosed herein.

Wireless power transmission device

Referring to FIG. 2A, the wireless power transmission apparatus is configured to include a power transmission unit 110. FIG. The power transmission unit 110 may include a power conversion unit 111 and a power transmission control unit 112.

The power conversion unit 111 converts the power supplied from the transmission power supply unit 190 into a wireless power signal and transmits the wireless power signal to the wireless power reception apparatus 200. The radio power signal transmitted by the power converter 111 is formed in the form of a magnetic field or an electro-magnetic field having oscillation characteristics. For this, the power conversion unit 111 may be configured to include a coil for generating the wireless power signal.

The power conversion unit 111 may include components for forming different types of wireless power signals according to each power transmission scheme. For example, the power conversion unit 111 may be configured to include a primary coil that forms a changing magnetic field in order to induce a current in the secondary coil of the wireless power receiving apparatus 200 according to an inductive coupling scheme have. The power conversion unit 111 may be configured to include a coil (or antenna) that forms a magnetic field having a specific resonance frequency in order to generate a resonance phenomenon in the wireless power receiving apparatus 200 according to a resonance coupling scheme have.

The power conversion unit 111 may transmit power using one or more of the inductive coupling method and the resonant coupling method described above.

Referring to FIGS. 4A, 4B, and 5, those elements in the inductive coupling scheme among the elements included in the power conversion unit 111 will be described with reference to FIGS. 7A, 7B, 8 below.

The power conversion unit 111 may further include a circuit for adjusting characteristics of a frequency, an applied voltage, and a current used for forming the wireless power signal.

The power transmission control unit 112 controls each component included in the power transmission unit 110. The power transmission control unit 112 may be integrated with another control unit (not shown) that controls the wireless power supply apparatus 100.

Meanwhile, an area where the wireless power signal can reach can be divided into two types. First, an active area refers to a region through which a wireless power signal that transmits power to the wireless power receiving apparatus 200 passes. Next, a semi-active area refers to a region of interest in which the wireless power transmission apparatus can detect the presence of the wireless power receiving apparatus 200. [ Here, the power transmission control unit 112 may detect whether the wireless power receiving apparatus 200 is placed in or removed from the active region or the sensing region. Specifically, the power transmission control unit 112 uses the wireless power signal generated by the power conversion unit 111 or the wireless power reception apparatus 200 is connected to the active area or the sensing area by a separately provided sensor It can be detected whether or not it has been deployed. For example, the power transmission control unit 112 receives the wireless power signal due to the wireless power receiving apparatus 200 existing in the sensing area, and forms the wireless power signal of the power conversion unit 111 The presence of the wireless power receiving apparatus 200 can be detected by monitoring whether or not the characteristic of the power for the wireless power receiving apparatus 200 changes. However, the active area and the sensing area may differ depending on a wireless power transmission scheme such as an inductive coupling scheme and a resonant coupling scheme.

The power transmission control unit 112 may perform the process of identifying the wireless power receiving apparatus 200 according to a result of detecting the presence of the wireless power receiving apparatus 200 or may determine whether to start wireless power transmission have.

The power transmission control unit 112 may determine at least one of a frequency, a voltage, and a current of the power conversion unit 111 for forming the wireless power signal. The determination of the characteristics may be made according to the condition of the wireless power transmission apparatus side or the condition of the wireless power reception apparatus 200 side.

The power transmission control unit 112 may receive a power control message from the wireless power receiving apparatus 200. [ The power transmission control unit 112 may determine one or more characteristics of the frequency, voltage, and current of the power conversion unit 111 based on the received power control message, Operation can be performed.

For example, the power transmission control unit 112 may form the wireless power signal according to a power control message including at least one of the rectified power amount information, the charging status information and the identification information of the wireless power receiving apparatus 200 It is possible to determine at least one of the characteristics of the frequency, current, and voltage to be used.

In addition, as another control operation using the power control message, the wireless power transmission apparatus can perform a general control operation related to wireless power transmission based on the power control message. For example, the wireless power transmission apparatus may receive information to be audibly or visually output related to the wireless power receiving apparatus 200 through the power control message, or may receive information necessary for authentication between devices.

In order to receive the power control message, the power transmission control unit 112 may use at least one of a method of receiving through the wireless power signal and a method of receiving other user data.

In order to receive the power control message, the wireless power transmission apparatus may further include a power communication modulation / demodulation unit 113 electrically connected to the power conversion unit 111. The modem unit 113 may be used to demodulate the wireless power signal modulated by the wireless power receiving apparatus 200 and receive the power control message.

In addition, in some embodiments, the power transmission control unit 112 may acquire a power control message by receiving user data including a power control message by communication means (not shown) included in the wireless power transmission apparatus It is possible.

[When supporting in-band two-way communication]

In addition, in the wireless power transmission environment capable of bidirectional communication according to the embodiments disclosed herein, the power transmission control unit 112 may transmit data to the wireless power receiving apparatus 200. [ The data transmitted by the power transmission control unit 112 may be a request for the wireless power receiving apparatus 200 to send a power control message.

Wireless power receiving device

Referring to FIG. 2B, the wireless power receiving apparatus 200 is configured to include a power supply unit 290. The power supply unit 290 supplies power required for operation of the wireless power receiving apparatus 200. The power supply unit 290 may include a power receiving unit 291 and a power receiving control unit 292.

The power receiving unit 291 receives power transmitted from the wireless power transmission apparatus to the wireless network.

The power receiving unit 291 may include components necessary for receiving the wireless power signal according to a wireless power transmission scheme. In addition, the power receiver 291 may receive power according to one or more wireless power transmission schemes. In this case, the power receiver 291 may include necessary components according to each scheme.

First, the power receiving unit 291 may be configured to include a coil for receiving a radio power signal transmitted in the form of a magnetic field or an electromagnetic field having an oscillating characteristic.

For example, as a component according to an inductive coupling scheme, the power receiving unit 291 may include a secondary coil whose current is induced by a changing magnetic field. The power receiving unit 291 may include a coil and a resonant circuit that generate a resonance phenomenon by a magnetic field having a specific resonance frequency as a component according to a resonant coupling scheme.

However, when the power receiving unit 291 receives power according to one or more wireless power transmission schemes, the power receiving unit 291 may be configured to receive using one coil, And may be implemented to receive using a coil.

Among the components included in the power receiving unit 291, those following the inductive coupling scheme will be described with reference to FIGS. 4A and 4B, and those with the resonant coupling scheme will be described later with reference to FIGS. 7A and 7B.

Meanwhile, the power receiving unit 291 may further include a rectifier and a regulator for converting the radio power signal into a direct current. The power receiving unit 291 may further include a circuit for preventing an overvoltage or an overcurrent from occurring due to the received power signal.

The power reception control unit 292 controls the components included in the power supply unit 290.

Specifically, the power reception control unit 292 may transmit a power control message to the wireless power transmission apparatus. The power control message may be to instruct the wireless power transmission apparatus to start or terminate transmission of the wireless power signal. The power control message may also direct the wireless power transmission device to adjust the characteristics of the wireless power signal.

In order to transmit the power control message, the power control unit 292 may use at least one of a method of transmitting through the wireless power signal and a method of transmitting through the other user data.

In order to transmit the power control message, the wireless power receiving apparatus 200 may further include a power communication modulation / demodulation unit 293 electrically connected to the power receiving unit 291. The modem unit 293 may be used to transmit the power control message through the wireless power signal, as in the case of the wireless power transmission apparatus described above. The modem unit 293 may be used as a means for adjusting the current and / or voltage flowing through the power conversion unit 111 of the wireless power transmission apparatus 100. Hereinafter, a method in which the modulation and demodulation units 113 and 293 on the wireless power transmission apparatus side and the wireless power reception apparatus 200 side are used for transmission and reception of a power control message through a wireless power signal will be described.

The wireless power signal formed by the power conversion unit 111 is received by the power receiving unit 291. At this time, the power reception control unit 292 controls the modem unit 293 of the wireless power receiving apparatus 200 to modulate the wireless power signal. For example, the power reception control unit 292 may modify the reactance of the modem unit 293 connected to the power reception unit 291 so that the amount of power received from the wireless power signal changes accordingly have. A change in the amount of power received from the wireless power signal results in a change in the current and / or voltage of the power conversion unit 111 forming the wireless power signal. At this time, the modulation / demodulation unit 113 on the side of the wireless power transmission apparatus detects a change in the current and / or voltage of the power conversion unit 111 and performs a demodulation process.

That is, the power reception controller 292 generates a packet including a power control message to be transmitted to the wireless power transmission apparatus, modulates the wireless power signal to include the packet, 112 can obtain the power control message included in the packet by decoding the packet based on the demodulation process result of the modem unit 113. [

In addition, in some embodiments, the power reception control unit 292 transmits user data including a power control message by communication means (not shown) included in the wireless power reception apparatus 200, To the wireless power transmission apparatus.

[When supporting in-band two-way communication]

In addition, in a wireless power transmission environment capable of bidirectional communication according to the embodiments disclosed herein, the power reception control unit 292 can receive data transmitted from the wireless power transmission apparatus. The data transmitted from the wireless power transmission apparatus may be to request to transmit a power control message.

In addition, the power supply unit 290 may be configured to further include a charging unit 298 and a battery 299.

The wireless power receiving apparatus 200 receiving the power for operation from the power supply unit 290 operates by the power transmitted from the wireless power transmission apparatus or by the battery 299 using the transmitted power, The battery 299 can be operated by the electric power charged in the battery 299. At this time, the power receiving control unit 292 may control the charging unit 298 to perform charging using the transmitted power.

Hereinafter, a wireless power transmission apparatus and a wireless power receiving apparatus applicable to the embodiments disclosed herein will be described. 3 to 5, a method of transmitting power by the wireless power transmission apparatus to the wireless power reception apparatus according to an inductive coupling scheme is disclosed.

Inductively coupled

3 illustrates a concept that power is transmitted from a wireless power transmission apparatus to a wireless power receiving apparatus wirelessly according to an inductive coupling scheme.

When the power transmission of the wireless power transmission apparatus follows the inductive coupling scheme, when the intensity of the current flowing through the primary coil in the power transmission unit 110 is changed, a magnetic field passing through the primary coil . The thus changed magnetic field generates an induced electromotive force on the secondary coil side of the wireless power receiving apparatus 200.

According to this scheme, the power conversion unit 111 of the wireless power transmission apparatus is configured to include a transmission coil (Tx coil) 1111a that operates as a primary coil in magnetic induction. The power receiving unit 291 of the wireless power receiving apparatus 200 is configured to include a receiving coil (Rx coil) 2911a that operates as a secondary coil in magnetic induction.

The wireless power transmission apparatus and the wireless power receiving apparatus 200 are arranged so that the transmission coil 1111a on the wireless power transmission apparatus side and the reception coil on the wireless power reception apparatus 200 side are close to each other. Thereafter, when the power transmission control unit 112 controls the current of the transmission coil 1111a to be changed, the power receiving unit 291 receives the power from the wireless power receiving apparatus 200 to be supplied with power.

The efficiency of the wireless power transmission by the inductively coupled system is less influenced by the frequency characteristics but is influenced by the alignment and distance between the wireless power transmission apparatus including the coils and the wireless power reception apparatus 200 distance).

On the other hand, for inductive coupling wireless power transmission, the wireless power transmission device may be configured to include an interface surface (not shown) in the form of a flat surface. One or more wireless power receiving devices may be disposed on the interface surface, and the transmission coil 1111a may be mounted on a lower surface of the interface. In this case, the vertical spacing between the transmission coil 1111a mounted on the lower surface of the interface and the reception coil 2911a of the wireless power receiving apparatus 200 located above the interface surface is made small The distance between the coils is sufficiently small so that wireless power transmission by the inductive coupling method can be efficiently performed.

In addition, an arrangement indicator (not shown) may be formed on the interface surface to indicate a position where the wireless power receiving apparatus 200 is to be placed. The arrangement indicator indicates the position of the wireless power receiving apparatus 200 in which the arrangement between the transmission coil 1111a mounted on the lower surface of the interface and the reception coil 2911a can be suitably adjusted. The arrangement indicator may be a simple mark or may be formed in the form of a protruding structure for guiding the position of the wireless power receiving apparatus 200. Or the array directing part is formed in the form of a magnetic body such as a magnet mounted on the lower surface of the interface so that the coils are arranged in an appropriate array by mutual attracting force with other magnetic bodies mounted inside the wireless power receiving apparatus 200 As shown in FIG.

Meanwhile, the wireless power transmission apparatus may be configured to include one or more transmission coils. The wireless power transmission apparatus may selectively use a part of the coils suitably arranged with the reception coil 2911a of the wireless power receiving apparatus 200 among the one or more transmission coils to increase the power transmission efficiency. A wireless power transmission apparatus including the one or more transmission coils will be described below with reference to Fig.

Hereinafter, a configuration of an inductively coupled wireless power transmission apparatus and a wireless power reception apparatus applicable to the embodiments disclosed herein will be described in detail.

Inductively coupled wireless power transmission apparatus and wireless power receiving apparatus

4A and 4B are block diagrams illustrating a portion of the configuration of a wireless power transmission apparatus and a wireless power transmission apparatus 200 of a magnetic induction type that can be employed in the embodiments disclosed herein. 4A, the configuration of the power transfer unit 110 included in the wireless power transmission apparatus will be described. Referring to FIG. 4B, the configuration of the power supply unit 290 included in the wireless power reception apparatus 200 will be described. The configuration will be described.

Referring to FIG. 4A, the power conversion unit 111 of the wireless power transmission apparatus may be configured to include a transmission coil (Tx coil) 1111a and an inverter 1112. FIG.

As described above, the transmission coil 1111a forms a magnetic field corresponding to a radio power signal in accordance with a change in current. The transmission coil 1111a may be implemented as a planar spiral type or a cylindrical solenoid type.

The inverter 1112 transforms a DC input obtained from the power supply unit 190 into an AC waveform. An alternating current deformed by the inverter 1112 is formed in the transmission coil 1111a by driving a resonant circuit including the transmission coil 1111a and a capacitor (not shown) .

In addition, the power conversion unit 111 may be further configured to include a positioning unit 1114.

The positioning unit 1114 may move or rotate the transmission coil 1111a to increase the efficiency of the wireless power transmission by the inductive coupling scheme. This is because, as described above, the power transmission by the inductively-coupled method is performed by adjusting the alignment and distance between the wireless power transmission apparatus including the primary and secondary coils and the wireless power- Because it is affected. In particular, the positioning unit 1114 may be used when the wireless power receiving apparatus 200 is not in the active area of the wireless power transmission apparatus.

Therefore, the positioning unit 1114 may determine that the distance between the center of the transmission coil 1111a of the wireless power transmission apparatus and the reception coil 2911a of the wireless power reception apparatus 200 is within a certain range And a driving unit (not shown) for moving the transmission coil 1111a so that the center of the transmission coil 1111a and the reception coil 2911a overlap with each other or rotating the transmission coil 1111a so as to overlap the center of the transmission coil 1111a and the reception coil 2911a .

The wireless power transmission apparatus may further include a position detection unit (not shown) configured to detect a position of the wireless power reception apparatus 200, May control the positioning unit 1114 based on position information of the wireless power receiving apparatus 200 received from the position sensing sensor.

For this, the power transmission control unit 112 receives control information on the arrangement or distance with the wireless power receiving apparatus 200 through the modulation / demodulation unit 113, and transmits control information on the received arrangement or distance The position determining unit 1114 can be controlled based on the position information.

If the power conversion unit 111 is configured to include a plurality of transmission coils, the positioning unit 1114 can determine which of the plurality of transmission coils is to be used for power transmission. The configuration of the wireless power transmission apparatus including the plurality of transmission coils will be described later with reference to Fig.

Meanwhile, the power conversion unit 111 may be configured to further include a power sensing unit 1115. The power sensing unit 1115 on the radio power transmission apparatus side monitors the current or voltage flowing in the transmission coil 1111a. The power sensing unit 1115 is used to check whether the wireless power transmission apparatus operates normally. The power sensing unit 1115 can detect a voltage or current of a power source supplied from the outside and check whether the detected voltage or current exceeds a threshold value . The power sensing unit 1115 compares a voltage or current value of the detected power source with a threshold value and outputs a result of the comparison. And a comparator. Based on the result of the detection by the power sensing unit 1115, the power transmission control unit 112 may control the switching unit (not shown) to cut off the power applied to the transmission coil 1111a.

Referring to FIG. 4B, the power supply unit 290 of the wireless power receiving apparatus 200 may be configured to include a receiving coil (Rx coil) 2911a and a rectifying circuit 2913.

A current is induced in the reception coil 2911a by a change in the magnetic field formed from the transmission coil 1111a. The receiving coil 2911a may be in the form of a flat spiral or cylindrical solenoid, as in the case of the transmitting coil 1111a.

In addition, series and parallel capacitors may be connected to the receiving coil 2911a to enhance reception efficiency of the wireless power or to detect resonance.

The receiving coil 2911a may be in the form of a single coil or a plurality of coils.

The rectifying circuit 2913 performs full-wave rectification on the current to convert the alternating current into direct current. The rectifier circuit 2913 may be implemented by, for example, a full bridge rectifier circuit including four diodes or a circuit using active components.

In addition, the rectifying circuit 2913 may further include a regulator for converting the rectified current into a more flat and stable direct current. The output power of the rectifying circuit 2913 is supplied to the respective components of the power supply unit 290. The rectifying circuit 2913 is a DC-DC converter that converts the output DC power to an appropriate voltage to match the power required for each component of the power supply unit 290 (for example, a circuit similar to the charging unit 298) (DC-DC converter).

The modulation and demodulation unit 293 may be constituted by a resistive element connected to the power receiving unit 291 and having a resistance varying with respect to a direct current and a capacitive element whose reactance is changed with respect to an alternating current . The power receiving control unit 292 may modulate the wireless power signal received by the power receiving unit 291 by changing the resistance or reactance of the modem unit 293.

The power supply unit 290 may further include a power sensing unit 2914. The power sensing unit 2914 of the wireless power receiving apparatus 200 monitors the voltage and / or the current of the power source rectified by the rectifying circuit 2913 and monitors the voltage and / or current of the rectified power source When the current exceeds the threshold value, the power receiving control unit 292 transmits a power control message to the wireless power transmission apparatus to transmit appropriate power.

A wireless power transmission apparatus configured with one or more transmission coils

5 is a block diagram of a wireless power transmission apparatus configured to have one or more transmission coils that receive power in accordance with an inductive coupling scheme employable in the embodiments disclosed herein.

Referring to FIG. 5, the power conversion section 111 of the wireless power transmission apparatus according to the embodiments disclosed herein may be configured with one or more transmission coils 1111a-1 to 1111a-n. The one or more transmission coils 1111a-1 to 1111a-n may be an array of partly overlapping primary coils. An active area may be determined by a portion of the one or more transmission coils.

The one or more transmission coils 1111a-1 to 1111a-n may be mounted below the interface surface. The power conversion unit 111 may further include a multiplexer 1113 for establishing and releasing connection of some of the one or more transmission coils 1111a-1 to 1111a-n .

When the position of the wireless power receiving apparatus 200 located on the interface surface is sensed, the power transmission control unit 112 controls the transmission power of the one or more transmission coils 1111a-1 to 1111a-n of the wireless power receiving apparatus 200 can be connected to the receiving coils 2911a of the wireless power receiving apparatus 200. [

For this, the power transmission control unit 112 may acquire the location information of the wireless power receiving apparatus 200. For example, the power transmission control unit 112 may acquire the position of the wireless power receiving apparatus 200 on the interface surface by the position sensing unit (not shown) provided in the wireless power transmission apparatus. As another example, the power transmission control unit 112 may use the one or more transmission coils 1111a-1 to 1111a-n to generate a power control message indicating the strength of the wireless power signal from an object on the interface surface, Acquiring position information of the wireless power receiving apparatus 200 by receiving a power control message indicating identification information of the object and determining which coil of the one or more transmission coils is close to the position based on the received result, You may.

On the other hand, the active area may be a part of the interface surface, and may refer to a portion through which a high efficiency magnetic field can pass when the wireless power transmission apparatus transmits power wirelessly to the wireless power reception apparatus 200. At this time, a single transmission coil or a combination of one or more transmission coils for forming a magnetic field passing through the active region may be referred to as a primary cell. Therefore, the power transmission control unit 112 determines an activity area based on the sensed position of the wireless power receiving apparatus 200, establishes connection of major cells corresponding to the active area, 200 and the coils belonging to the main cell can be placed in the inductive coupling relationship with each other.

The power conversion unit 111 may further include an impedance matching unit (not shown) for adjusting the impedance to form a resonant circuit with the coils connected thereto.

Hereinafter, a method of transmitting power according to a resonant coupling scheme by a wireless power transmission apparatus is described with reference to FIGS.

Resonance coupling method

FIG. 6 illustrates a concept that power is transmitted from a wireless power transmission apparatus to a wireless power reception apparatus wirelessly according to a resonant coupling scheme.

First, the resonance (or resonance) will be briefly described as follows. Resonance refers to a phenomenon in which the vibration system receives an external force periodically having the same frequency as its natural frequency, and the amplitude thereof increases sharply. Resonance is a phenomenon occurring in all vibrations, such as mechanical vibration and electrical vibration. Generally, when a force capable of vibrating the vibration system is applied from the outside, if the natural frequency of the vibration system is equal to the frequency of the external force, the vibration becomes larger and the amplitude becomes larger.

In the same principle, when a plurality of vibrating bodies separated within a certain distance oscillate at the same frequency, the plurality of vibrating bodies resonate with each other, and in this case, the resistance between the vibrating bodies decreases. In an electric circuit, an inductor and a capacitor can be used to make a resonant circuit.

When the power transmission of the wireless power transmission apparatus follows the resonant coupling scheme, a magnetic field having a specific vibration frequency is formed by the AC power source in the power transmission unit 110. When a resonance phenomenon occurs in the wireless power receiving apparatus 200 due to the magnetic field, power is generated in the wireless power receiving apparatus 200 by the resonance phenomenon.

The resonance frequency can be determined by, for example, the following equation (1).

Here, the resonance frequency f is determined by the inductance L and the capacitance C in the circuit. In a circuit for forming a magnetic field using a coil, the inductance is determined by the number of revolutions of the coil and the like, and the capacitance can be determined by an interval, an area, or the like between the coils. A capacitive resonance circuit may be connected to the coil to determine the resonance frequency.

Referring to FIG. 6, when power is transmitted wirelessly according to the resonant coupling scheme, the power conversion unit 111 of the wireless power transmission apparatus includes a transmission coil (Tx coil) 1111b in which a magnetic field is formed, And a resonance circuit 1116 connected to the resonance circuit 1111b and for determining a specific oscillation frequency. The resonant circuit 1116 can be implemented using capacitors and the specific oscillation frequency is determined based on the inductance of the transmission coil 1111b and the capacitance of the resonant circuit 1116. [

The configuration of the circuit elements of the resonant circuit 1116 may be variously configured to form a magnetic field by the power conversion unit 111 and may be connected in parallel with the transmission coil 1111b as shown in FIG. It is not limited.

The power receiving unit 291 of the wireless power receiving apparatus 200 includes a resonant circuit 2912 and a receiving coil (Rx coil) 2911b configured to cause a resonance phenomenon by a magnetic field formed in the wireless power transmission apparatus, . That is, the resonance circuit 2912 may be implemented using a capacitive circuit, and the resonance circuit 2912 is determined based on the inductance of the reception coil 2911b and the capacitance of the resonance circuit 2912 And the resonance frequency is equal to the resonance frequency of the magnetic field formed.

 The configuration of the circuit elements of the resonant circuit 2912 may be variously configured to allow the power receiving unit 291 to resonate by the magnetic field and may be connected in series with the receiving coil 2911b as shown in FIG. But is not limited to.

The specific vibration frequency in the wireless power transmission apparatus may be obtained using Equation 1 with LTx, CTx. Here, resonance occurs in the wireless power receiving apparatus 200 when the result of substituting the LRX and CRX of the wireless power receiving apparatus 200 into Equation 1 is equal to the specific vibration frequency.

The efficiency of the wireless power transmission by the resonance coupling method is largely influenced by the frequency characteristics, while the influence of the arrangement and the distance between the wireless power transmission apparatus including the coils and the wireless power reception apparatus 200 Is relatively small compared with the inductive coupling method.

Hereinafter, a configuration of a wireless power transmission apparatus and a wireless power reception apparatus of a resonance coupling type applicable to the embodiments disclosed herein will be described in detail.

Resonant coupling type wireless power transmission device

7A and 7B are block diagrams exemplarily showing a part of the configuration of a wireless power transmission apparatus and a wireless power receiving apparatus 200 of a resonance type that can be employed in the embodiments disclosed herein.

The configuration of the power transmission unit 110 included in the wireless power transmission apparatus will be described with reference to FIG. 7A.

The power conversion unit 111 of the wireless power transmission apparatus may be configured to include a transmission coil (Tx coil) 1111b, an inverter 1112, and a resonant circuit 1116. [ The inverter 1112 may be configured to be connected to the transmission coil 1111b and the resonant circuit 1116.

The transmission coil 1111b may be mounted separately from the transmission coil 1111a for transmitting electric power according to the inductive coupling scheme, but it may also transmit power using an inductive coupling scheme or a resonant coupling scheme using one single coil.

The transmission coil 1111b forms a magnetic field for transmitting electric power, as described above. The transmission coil 1111b and the resonance circuit 1116 may be vibrated when the AC power is applied and at this time the oscillation frequency is set to a value based on the inductance of the transmission coil 1111b and the capacitance of the resonance circuit 1116 Can be determined.

To this end, the inverter 1112 transforms a DC input obtained from the power supply unit 190 into an AC waveform, and the transformed AC current is applied to the transmission coil 1111b and the resonance circuit 1116.

In addition, the power conversion unit 111 may further include a frequency adjustment unit 1117 for changing the resonance frequency value of the power conversion unit 111. Since the resonance frequency of the power conversion unit 111 is determined based on the inductance and the capacitance in the circuit constituting the power conversion unit 111 according to Equation 1, the power transmission control unit 112 controls the inductance and / The resonance frequency of the power converter 111 can be determined by controlling the frequency adjuster 1117 so that the capacitance is changed.

The frequency adjuster 1117 may include a motor capable of changing the capacitance by adjusting the distance between the capacitors included in the resonant circuit 1116 or may include a motor for changing the number of rotations of the transmission coil 1111b number of turns, or a motor capable of changing the inductance by adjusting the diameter, or it may be configured to include active elements that determine the capacitance and / or inductance.

Meanwhile, the power conversion unit 111 may be configured to further include a power sensing unit 1115. The operation of the power sensing unit 1115 is the same as described above.

The configuration of the power supply unit 290 included in the wireless power receiving apparatus 200 will be described with reference to FIG. The power supply 290 may be configured to include the receive coil (Rx coil) 2911b and the resonant circuit 2912, as described above.

In addition, the power receiving unit 291 of the power supply unit 290 may be configured to further include a rectifying circuit 2913 that converts the alternating current generated by the resonance phenomenon to direct current. The rectifying circuit 2913 may be constructed in the same manner as described above.

The power receiving unit 291 may further include a power sensing unit 2914 for monitoring the voltage and / or current of the rectified power. The power sensing unit 2914 may be configured as described above.

A wireless power transmission apparatus configured with one or more transmission coils

8 is a block diagram of a wireless power transmission apparatus configured to have one or more transmission coils that receive power in accordance with a resonant coupling scheme employable in the embodiments disclosed herein.

8, the power conversion section 111 of the wireless power transmission apparatus according to the embodiments disclosed herein includes one or more transmission coils 1111b-1 to 1111b-n and a resonance circuit 1116-1 through 1116-n). The power conversion unit 111 may further include a multiplexer 1113 for establishing and releasing a connection of some of the one or more transmission coils 1111b-1 to 1111b-n .

The one or more transmission coils 1111b-1 to 1111b-n may be set to have the same resonance frequency, or may be set so that some have different resonance frequencies. Which is determined according to what inductance and / or capacitance the resonant circuits 1116-1 through 1116-n respectively connected to the one or more transmission coils 1111b-1 through 1111b-n have.

The frequency adjuster 1117 may change the inductance and / or capacitance of the resonant circuits 1116-1 through 1116-n connected to the one or more transmission coils 1111b-1 through 1111b-n, Or < / RTI >

[[In-band communication]]

9 illustrates a concept of transmitting and receiving packets between a wireless power transmission device and an electronic device through modulation and demodulation of a wireless power signal in wireless power transmission according to the embodiments disclosed herein.

Referring to FIG. 9, the power conversion unit 111 included in the wireless power transmission apparatus forms a wireless power signal. The wireless power signal is formed through a transmission coil 1111 included in the power conversion unit 111.

The wireless power signal 10a formed by the power conversion unit 111 reaches the electronic device 200 and is received through the power receiving unit 291 included in the electronic device 200. [ The generated radio power signal is received through a receiving coil 2911 included in the power receiving unit 291.

The power reception control unit 292 controls the modulation / demodulation unit 293 connected to the power reception unit 291 to modulate the wireless power signal while the electronic device 200 receives the wireless power signal . When the received wireless power signal is modulated, the wireless power signal forms a closed-loop within a magnetic field or an electro-magnetic field, When modulating the wireless power signal while receiving the power signal, the wireless power transmission apparatus can sense the modulated wireless power signal 10b. Demodulation unit 113 demodulates the detected radio power signal and decodes the packet from the demodulated radio power signal.

Meanwhile, a modulation method used for communication between the wireless power transmission apparatus and the electronic device 200 may be amplitude modulation. As described above, in the amplitude modulation method, the modulation / demodulation unit 293 of the electronic device 200 side changes the amplitude of the wireless power signal 10a formed by the power conversion unit 111, Demodulating unit 293 may be a backscatter modulation method for detecting the amplitude of the modulated wireless power signal 10b.

Modulation and demodulation of wireless power signals

Modulation and demodulation of packets transmitted and received between the wireless power transmission apparatus and the electronic apparatus 200 will be described below with reference to Figs. 10, 11A, 11B, and 11C.

10 illustrates a configuration for transmitting and receiving a power control message in a wireless power transmission according to the embodiments disclosed herein. 11A, 11B, and 11C illustrate the form of signals in modulation and demodulation performed in a wireless power transmission in accordance with the embodiments disclosed herein.

Referring to FIG. 10, a wireless power signal received through the power receiving unit 291 on the electronic device 200 side is a wireless power signal 51 that is not modulated as shown in FIG. 11A. Resonance coupling is performed between the electronic device 200 and the wireless power transmission apparatus according to the resonance frequency set by the resonance forming circuit 2912 in the power receiving unit 291, Power signal 51 is received.

The power reception control unit 292 modulates the wireless power signal 51 received through the power reception unit 291 by changing the load impedance in the modem unit 293. The modulation and demodulation unit 293 may be configured to include a passive element 2931 and an active element 2932 for modulating the wireless power signal 51. [ The modem unit 293 modulates the wireless power signal 51 to include a packet to be transmitted to the wireless power transmission apparatus. At this time, the packet may be input to the active element 2932 in the modem unit 293.

Thereafter, the power transmission control unit 112 of the wireless power transmission apparatus side demodulates the modulated wireless power signal 52 through an envelope detection process, and outputs the detected signal 53 as digital data 54). The demodulation process detects that the current or voltage flowing through the power conversion unit 111 is divided into two states, i.e., a HI state and an LO state by the modulated wireless power signal, The electronic device 200 acquires a packet to be transmitted by the electronic device 200 based on digital data classified according to the type of the digital data.

Hereinafter, the process of acquiring the power control message to be transmitted by the electronic device 200 from the digital data demodulated by the wireless power transmission apparatus will be described.

Referring to FIG. 11B, the power transmission control unit 112 detects an encoded bit using a clock signal CLK from an envelope-detected signal. The detected encoded bits are encoded according to the bit encoding method used in the modulation process on the electronic device 200 side. In some embodiments, the bit encoding method may be NRZ (non-return to zero). In some embodiments, the bit encoding method may be bi-phase encoding.

For example, in some embodiments, the detected bits may be differential bi-phase (DBP) encoded. According to the DBP encoding, the power reception control unit 292 of the electronic device 200 has two state transitions to encode the data bit 1, and one state transition to encode the data bit 0, . That is, the data bit 1 is encoded such that the transition between the HI state and the LO state occurs at the rising edge and the falling edge of the clock signal, and the data bit 0 is at the rising edge of HI State and the LO state may be encoded to occur.

On the other hand, the power transmission control unit 112 can obtain data in units of bytes by using a byte format that forms a packet from the bit stream detected according to the bit encoding method. In some embodiments, the detected bit stream may be transmitted using an 11-bit asynchronous serial format as shown in FIG. 11C. That is, it may include a start bit indicating the start of the byte and a stop bit indicating the end, and may include data bits (b0 through b7) between the start bit and the end bit. In addition, a parity bit for checking the error of the data may be added. The byte-by-byte data constitutes a packet including a power control message.

[When in-band two-way communication is supported]

Although the wireless power receiving apparatus 200 shown in FIG. 9 transmits a packet using a carrier signal 10a formed by the wireless power transmission apparatus 100, The device 100 may also transmit data to the wireless power receiving device 200 in a similar manner.

That is, the power transmission control unit 112 may control the modulation / demodulation unit 113 to modulate the data to be sent to the wireless power reception apparatus 200 to be written on the carrier signal 10a. In this case, the demodulation unit 293 is controlled to demodulate the power reception control unit 292 of the wireless power receiving apparatus 200 so that the power reception control unit 292 can acquire data from the modulated carrier signal 10a .

Packet format

Hereinafter, the structure of a packet used in communication using a wireless power signal according to the embodiments disclosed herein will be described.

12A, 12B and 12C illustrate a packet including a power control message used in a wireless power transfer method according to the embodiments disclosed herein.

Referring to FIG. 12A, the wireless power transmission apparatus and the electronic device 200 may transmit and receive data to be transmitted in the form of a command packet (command_packet) 510. The command packet 510 may be configured to include a header 511 and a message 512.

The header 511 may include a field indicating a type of data included in the message 512. The size and type of the message can be determined based on a value indicated by a field indicating the type of the data.

In addition, the header 511 may include an address field for identifying a sender of the packet. For example, the address field may indicate an identifier of the electronic device 200 or an identifier of a group to which the electronic device 200 belongs. When the electronic device 200 wants to transmit the packet 510, the electronic device 200 generates the packet 510 so that the address field of the packet 510 indicates its own identification information can do.

The message 512 includes data that the sender of the packet 510 wants to transmit. The data included in the message 512 may be a report, a request, or a response to the other party.

Meanwhile, in some embodiments, the instruction packet 510 may be configured as shown in FIG. 12B. The header 511 included in the command packet 510 may be represented by a predetermined size. For example, the header 511 may be two bytes in size.

The header 511 may be configured to include a destination address field 5111. For example, the destination address field may be six bits in size.

The header 511 may be configured to include an operation command field (OCF) 5112 or an operation group field (OGF) 5113. The OGF 5113 is a value assigned to each group of commands for the electronic device 200. The OCF 5112 is a value assigned to each command included in each group including the electronic device 200. [

The message 512 may be divided into a parameter length field 5121a and a parameter value field 5122a. That is, the sender of the packet 510 may configure the message in the form of length-value pairs (5121a-5122a, etc.) of one or more parameters required to express the data to be transmitted.

Referring to FIG. 12C, the wireless power transmission apparatus and the electronic device 200 transmit and receive the data in the form of a packet in which a preamble 520 and a checksum 530 for transmission are added to the command packet 510 .

The preamble 520 is used for the wireless power transmission apparatus to perform synchronization with the received data and accurately detect the start bit of the command packet 510. The preamble 520 may be configured to repeat the same bit. For example, the preamble 520 may be configured such that the data bit 1 according to the DBP encoding is repeated 11 to 25 times.

The checksum 530 is used to detect an error that may occur in the command packet 510 during the transmission of the power control message.

Phases

Hereinafter, the operation states of the wireless power transmission apparatus and the wireless power reception apparatus 200 in the one-to-one communication will be described.

13 illustrates operating states of a wireless power transmission apparatus and a wireless power receiving apparatus 200 according to the embodiments disclosed herein. 14 to 18 illustrate the structure of packets including the power control message between the wireless power transmission apparatus and the wireless power reception apparatus 200. FIG.

13, an operation state of a wireless power receiving apparatus 200 for wireless power transmission according to an exclusive scheme includes a Selection Phase 610, a Ping Phase 620, An Identification and Configuration Phase 630, and a Power Transfer Phase 640. [0064]

In the selected state 610, the wireless power transmission apparatus senses whether or not objects exist within a range capable of wirelessly transmitting power, and in the detection state 620, The wireless power receiving apparatus 200 sends a detection signal to the object, and the wireless power receiving apparatus 200 sends a response to the detection signal.

Also, in the identifying and setting state 630, the wireless power transmission apparatus identifies the selected wireless power receiving apparatus 200 through the previous states and acquires setting information for power transmission. In the power transmission state 640, the wireless power transmission apparatus transmits power to the wireless power reception apparatus 200 while adjusting power to be transmitted in response to the control message received from the wireless power reception apparatus 200 do.

Hereinafter, the respective operation states will be described in detail.

1) Selection Phase

The wireless power transmission apparatus in the selected state 610 performs a detection process to select the wireless power receiving apparatus 200 existing in the sensing area. As described above, the sensing area refers to an area where an object in the area can affect the characteristics of the power of the power conversion part 111. [ The detection process for selecting the wireless power receiving apparatus 200 in the selected state 610, as compared with the detection state 620, receives a response from the wireless power receiving apparatus 200 using the power control message The power conversion unit of the wireless power transmission apparatus side detects the change of the amount of power for forming the wireless power signal and checks whether an object exists within a certain range. The detection process in the selected state 610 may be referred to as an analog detection process (analog ping) in that an object is detected using a wireless power signal without using a digital format packet in a detection state 620 to be described later .

The wireless power transmission apparatus in the selected state 610 may detect that an object enters or exits the sensing area. In addition, the wireless power transmission apparatus can distinguish the wireless power receiving apparatus 200 and other objects (e.g., keys, coins, etc.) capable of wirelessly transmitting power among objects in the sensing area.

As described above, since the distance over which the electric power can be transmitted wirelessly differs according to the inductive coupling method and the resonant coupling method, the sensing area where the object is detected in the selected state 610 may be different from each other.

First, when power is transmitted according to the inductive coupling scheme, the wireless power transmission apparatus of the selected state 610 may monitor the interface surface (not shown) to detect placement and removal of objects.

In addition, the wireless power transmission apparatus may sense the position of the wireless power receiving apparatus 200 placed on the interface surface. As described above, a wireless power transmission apparatus configured to include one or more transmission coils enters the detection state 620 in the selected state 610 and uses the respective coils in the detection state 620 to determine (630) and confirms whether or not the identification information is transmitted from the object. The method of the present invention may be used to confirm whether or not a response to the detection signal is transmitted from the object. The wireless power transmission apparatus can determine a coil to be used for wireless power transmission based on the position of the sensed wireless power receiving apparatus 200 obtained through the above process.

Also, when power is transmitted according to the resonant coupling scheme, the wireless power transmission apparatus of the selected state 610 detects that at least one of frequency, current, and voltage of the power conversion unit due to an object in the sensing area is changed The object can be detected.

Meanwhile, the wireless power transmission apparatus in the selected state 610 can detect an object by at least one of the inductive coupling method and the resonant coupling method detection method. The wireless power transmission apparatus performs an object detection process according to each power transmission method and then detects the object among the combining methods for wireless power transmission in order to proceed to other states 620, 630, and 640 You can choose.

On the other hand, in the wireless power transmission apparatus of the selected state 610, the wireless power signal to be formed for detecting an object and the digital detection, identification, setting, and power transmission in the following states 620, 630 and 640 The generated wireless power signal may have different characteristics such as frequency, intensity, and the like. This is because the selected state 610 of the wireless power transmission apparatus corresponds to an idle phase for detecting an object, so that the wireless power transmission apparatus can reduce the power consumption in the air or provide a specialized signal To be able to generate the data.

2) Detection status (Ping Phase)

The wireless power transmission apparatus in the detection state 620 detects a wireless power reception apparatus 200 existing in the sensing area through a power control message. In comparison with the detection process of the wireless power receiving apparatus 200 using the characteristics of the wireless power signal in the selected state 610, the detection process in the detection state 620 may be referred to as digital ping have.

In the detection state 620, the wireless power transmission apparatus forms a wireless power signal for detecting the wireless power receiving apparatus 200, demodulates the wireless power signal modulated by the wireless power receiving apparatus 200 And obtains a power control message in the form of digital data corresponding to the response to the detection signal from the demodulated radio power signal. The wireless power transmission apparatus can recognize the wireless power receiving apparatus 200 that is a target of power transmission by receiving a power control message corresponding to a response to the detection signal.

The detection signal formed by the wireless power transmission apparatus in the detection state 620 to perform the digital detection process may be a wireless power signal formed by applying a power signal of a specific operating point for a predetermined time. The operating point may refer to a frequency, a duty cycle and an amplitude of a voltage applied to the Tx coil. The wireless power transmission apparatus can generate the detection signal generated by applying the power signal of the specific operating point for a predetermined time and attempt to receive the power control message from the wireless power receiving apparatus 200. [

Meanwhile, the power control message corresponding to the response to the detection signal may be a message indicating the strength of the wireless power signal received by the wireless power receiving apparatus 200. For example, the wireless power receiving apparatus 200 may include a signal strength packet 5100 including a message indicating the strength of a received wireless power signal as a response to the detection signal as shown in FIG. 14 Can be transmitted. The packet 5100 may be configured to include a header 5120 indicating that the packet is a packet indicating the signal strength and a message 5130 indicating the strength of the power signal received by the wireless power receiving apparatus 200. The strength of the power signal in the message 5130 may be a value indicative of the degree of coupling of inductive coupling or resonant coupling for power transmission between the wireless power transmission device and the wireless power receiving device 200. [

The wireless power transmission apparatus may receive the response message to the detection signal and detect the wireless power receiving apparatus 200 and then extend the digital detection process to enter the identification and detection state 630. [ That is, the wireless power transmission apparatus can receive the power control message required in the identification and detection state 630 by keeping the power signal of the specific operating point after discovery of the wireless power receiving apparatus 200.

However, if the wireless power transmission apparatus does not find the wireless power receiving apparatus 200 capable of transmitting the power, the operational state of the wireless power transmission apparatus may be returned to the selected state 610.

3) Identification and Configuration Phase

The wireless power transmission apparatus in the identification and setting state 630 may receive the identification information and / or the setting information transmitted from the wireless power receiving apparatus 200 and control the power transmission to be performed efficiently.

In the identifying and setting state 630, the wireless power receiving apparatus 200 may transmit a power control message including its identification information. For this purpose, the wireless power receiving apparatus 200 can transmit an identification packet (Identification Packet) 5200 including a message indicating identification information of the wireless power receiving apparatus 200 as shown in FIG. 15A have. The packet 5200 may be configured to include a header 5220 indicating that it is a packet indicating identification information, and a message 5230 including identification information of the wireless power receiving apparatus. The message 5230 includes information 2531 and 5232 indicating a version of a protocol for wireless power transmission, information 5233 identifying a manufacturer of the wireless power receiving apparatus 200, information indicating the presence or absence of an extension device identifier A base station identifier 5234 and a base unit identifier 5235. [ In addition, when it is indicated that the extension device identifier exists in the information 5234 indicating the presence or absence of the extension device identifier, an Extended Identification Packet 5300 including the extension device identifier as shown in FIG. Can be transmitted separately. The packet 5300 may be configured to include a header 5320 indicating that the packet is an extension device identifier, and a message 5330 including an extension device identifier. When the extension device identifier is used as described above, it is possible to identify the wireless power receiving apparatus 200 based on the identification information 5233 of the manufacturer, the base unit identifier 5235 and the extension unit identifier 5330 Information can be used.

In the identifying and setting state 630, the wireless power receiving apparatus 200 may transmit a power control message including information on the estimated maximum power. For this purpose, the wireless power receiving apparatus 200 can transmit, for example, a configuration packet (Configuration Packet) 5400 as shown in FIG. The packet may be configured to include a header 5420 indicating that it is a configuration packet and a message 5430 containing information on the expected maximum power. The message 5430 includes a power class 5431, information 5432 about the expected maximum power, an indicator 5433 indicating how to determine the current of the primary cell on the wireless power transmission side, 5434). The indicator 5433 may indicate whether or not the current of the main cell of the wireless power transmission apparatus side is to be determined as specified in the protocol for wireless power transmission.

Meanwhile, the wireless power transmission apparatus can generate a power transfer contract to be used for power charging with the wireless power receiving apparatus 200 based on the identification information and / or the setting information. The power transfer protocol may include limits of parameters that determine the power transfer characteristics in the power transfer state 640. [

The wireless power transmission apparatus may terminate the identification and setting state 630 and return to the selected state 610 before entering the power delivery state 640. [ For example, the wireless power transmission apparatus may terminate the identification and setting state 630 to find another wireless power receiving apparatus capable of receiving power wirelessly.

4) Power Transfer Phase (Power Transfer Phase)

The wireless power transmission apparatus in the power transmission state 640 transmits power to the wireless power receiving apparatus 200. [

The wireless power transmission apparatus may receive a power control message from the wireless power receiving apparatus 200 during transmission of power and may adjust characteristics of power applied to the transmission coil in accordance with the received power control message. For example, a power control message used to adjust the power characteristic of the transmission coil may be included in a control error packet 5500 as shown in FIG. The packet 5500 may be configured to include a header 5520 indicating that the packet is a control error packet and a message 5530 including a control error value. The wireless power transmission apparatus may adjust the power applied to the transmission coil according to the control error value. That is, the current applied to the transmission coil is maintained when the control error value is 0, decreased when the control value is a negative value, and can be adjusted to increase when the control value is a positive value.

In the power transfer state 640, the wireless power transmission device may monitor parameters in a power transfer contract generated based on the identification information and / or configuration information. As a result of monitoring the parameters, if the power transmission to the wireless power receiving apparatus 200 violates the limitations contained in the power transfer protocol, the wireless power transmission apparatus cancels the power transmission, It is possible to return to step 610.

The wireless power transmission apparatus may terminate the power transmission state 640 based on the power control message transmitted from the wireless power receiving apparatus 200. [

For example, if the charging of the battery is completed while the wireless power receiving apparatus 200 is charging the battery using the transmitted power, a power control message requesting the wireless power transmission apparatus to stop the wireless power transmission . In this case, the wireless power transmission apparatus may terminate the wireless power transmission and return to the selected state 610 after receiving the message requesting the suspension of the power transmission.

As another example, the wireless power receiving apparatus 200 may transmit a power control message requesting renegotiation or reconfiguration to update the already generated power transfer protocol. The wireless power receiving apparatus 200 may transmit a message requesting renegotiation of the power transfer protocol when a power amount that is more or less than the currently transmitted power amount is required. In this case, the wireless power transmission apparatus may terminate the wireless power transmission and return to the identification and setting state 630 after receiving the message requesting renegotiation of the power transfer protocol.

To this end, the message transmitted by the wireless power receiving apparatus 200 may be, for example, an End Power Transfer Packet 5600 as shown in FIG. The packet 5600 may be configured to include a header 5620 indicating that the packet is a power transmission interruption packet and a message 5630 including a power transmission interruption code indicating the reason for the interruption. The power transmission interruption code may be a code for determining whether or not the power transmission interruption code is in a state of charge completion, an internal fault, an over temperature, an over voltage, an over current, a battery failure, a reconfigure, No Response, or Unknown.

A communication method of a plurality of electronic devices

Hereinafter, a method in which one or more electronic devices from one wireless power transmission apparatus performs communication using a wireless power signal will be described.

19 is a conceptual diagram showing a method by which a wireless power transmission apparatus transmits electric power to one or more wireless power reception apparatuses.

The wireless power transmission apparatus may transmit power for one or more wireless power receiving apparatuses 200, 200 '. Although two electronic devices 200 and 200 'are shown in FIG. 19, the method according to the embodiments disclosed herein is not limited to the number of electronic devices shown.

The active area and the sensing area differ depending on the wireless power transmission scheme of the wireless power transmission apparatus. Accordingly, the wireless power transmission apparatus may be configured to determine whether there is a wireless power receiving apparatus disposed in an active region or a sensing region of a resonant coupling scheme, or whether there is a wireless power receiving apparatus disposed in an active region or an inductive coupling type sensing region Can be determined. According to the determination result, the wireless power transmission apparatus 100 supporting each wireless power transmission scheme can change the power transmission scheme for each wireless power reception apparatus.

In the wireless power transmission according to the embodiments disclosed herein, when the wireless power transmission device transmits power for one or more electronic devices 200, 200 'in the same wireless power transfer scheme, the electronic devices 200 , 200 'can communicate through the wireless power signal without collision.

As shown in FIG. 19, the wireless power signal 10a formed by the wireless power transmission device reaches the first electronic device 200 'and the second electronic device 200. The first electronic device 200 'and the second electronic device 200 may transmit a power control message using the generated wireless power signal.

The first electronic device 200 'and the second electronic device 200 operate as power receiving devices for receiving wireless power signals. The power receiving apparatus according to embodiments disclosed herein may include a power receiving unit (291 ', 291) for receiving the formed wireless power signal; A modulation and demodulation unit (293 ', 293) for modulating and demodulating the received wireless power signal; And control units 292 'and 292 for controlling the respective components of the power receiving apparatus.

External object detection method

Hereinafter, a method of detecting a foreign object (FOD: Foreign Object Detection) when an external object is close to or lying on a wireless power transmission apparatus that is configured to transmit power wirelessly to a wireless power receiving apparatus, We will look at it in detail.

20 is a circuit diagram exemplarily showing a part of the configuration of a radio-frequency power transmission apparatus of a magnetic induction type that can be employed in the embodiments disclosed in this specification. Referring to the block diagram of the wireless power transmission apparatus of Figs. 4A and 7A, the circuit diagram of Fig. 20 shows a power supply unit 190, an inverter 1112 and a transmission coil 1111a shown in Figs. 4A and 7A, ).

According to the illustrated example, the power supply unit 190 is electrically connected to the inverter 1112. For example, the power supply 190 provides a DC input to the transmission device 100 and the DC input is provided to the inverter 1112 of the transmission device 100 to generate an AC waveform AC waveform).

The inverter 1112 performs half-wave rectification or full-wave rectification on the current to convert the direct current to alternating current.

The inverter 1112 outputs a signal for detecting whether an external object is placed in the wireless power transmission apparatus 100. More specifically, the inverter 1112 inputs a pulse width modulation (PWM) signal generated during the reference time ΔT1 to detect whether an external object is placed in the wireless power transmission apparatus 100 And outputs a half-wave rectified or full-wave rectified signal to the transmission coil 1111a.

The transmission coil 1111a converts the half-wave rectified or full-wave rectified current output from the inverter 1112 into magnetic flux. The transmission coil 1111a wirelessly transmits power to the reception coil 2911b of the reception apparatus 200 shown in FIG. 4B and FIG. 7B and generates a magnetic field changing in the transmission coil 1111a A current is induced on the receiving coil 2911b side to transmit electric power.

The capacitor 1111c is disposed between the transmission coil 1111a and the inverter 1112 and is configured to generate a resonance frequency as shown in Equation 1 based on the inductance of the transmission coil 1111a and the capacitance of the transmission coil 1111a Thereby determining the resonant frequency of the transmission device.

The transmission apparatus having the capacitor 1111c described above is configured to detect whether or not an external object is placed in the transmission apparatus, not the reception apparatus. Hereinafter, such a detection process will be described with reference to Figs. 21 and 22. Fig.

21 and 22 are flowcharts showing a method of detecting an external object of a wireless power transmission apparatus of a magnetic induction type that can be employed in the embodiments disclosed herein. The external object detection method is performed by the power transmission control unit 112 of the transmission apparatus shown in Figs. 4A and 7A.

The external object detection method of FIG. 21 includes an analog ping step 2100, a frequency characteristic acquisition step 2200 of a current flowing through the transmission coil, a digital ping step 2300, 2400 and a power transmission step 2500. [

Referring to FIG. 21, the identifying and setting step 2400 and the power transmitting step 2500 correspond to the identifying and setting state 630 and the power transmitting state 640 of FIG. 13, respectively. Accordingly, the description of the identifying and setting step 2400 and the power transfer step 2500 is replaced with the description of the identification and setting state 630 and the power transfer state 640 described above.

The analog detection step 2100 of FIG. 21 includes an analog detection signal transmission step 2110 and a current comparison step 2120 as shown in FIG.

In the analog detection signal transmission step 2110, the transmission apparatus transmits an analog ping signal to the reception apparatus.

In this step, it can be judged whether or not the receiving apparatus or the external object is placed in the transmitting apparatus. This determination is made through a comparison of the currents, so the current comparison step proceeds after the signal is transmitted.

More specifically, the transmission unit is a current (I _coil) flowing through the transmission coil (1111a), the first threshold value (I _{coil _ thr)} or more (I _coil> I _{coil _ thr)} in the current comparison step 2120 , It is determined that the receiving apparatus or the external object is not placed in the transmitting apparatus.

The transmission device transmits the analog detection signal to the analog detection signal transmission step 2110 in order to determine whether the reception device or the external object is placed, .

On the other hand, if the transmission unit is a current (I _coil) is a first threshold value (I _{coil _ thr)} or less (I _coil <I _{coil _ thr)} flowing through the transmission coil (1111a) in the current comparison step 2120, It is determined that the receiving apparatus or the external object is placed in the transmitting apparatus.

Also, in order to determine whether the receiving apparatus is placed on the transmission apparatus or whether the external object is placed on the transmission apparatus, the transmission apparatus performs the frequency characteristic acquiring step (2200). The frequency characteristic acquiring step 2200 includes a frequency domain transforming step 2210, a current comparing step 2220 and a resonant frequency comparing step 2230. [

The frequency domain transforming step 2210 transforms the time domain value of the current flowing through the transmission coil 1111a into a frequency domain value for a predetermined time ΔT2 to obtain the frequency characteristic of the current.

The current comparison step 2220 determines that that if the peak value of the electric current (I _{coil _ peak)} is the second threshold value (I _{coil _ thr)} over to the transmission device is the receiving device and the external object is not placed .

This corresponds to the case where the receiving apparatus or the external object is not placed in the transmitting apparatus, and the transmitting apparatus repeats the above-described analog detecting signal transmitting step 2110 to determine whether the receiving apparatus or the external object is placed .

The determination is made that if the peak value of the electric current from the current comparison step _{(2220) (I coil _ peak} ) is the second threshold value (I _{coil _ thr)} or less, in the transfer apparatus is put the receiving device or the external object; do.

Also, in order to determine whether the receiving apparatus is placed on the transmitting apparatus or whether the external apparatus is placed on the transmitting apparatus, the transmitting apparatus performs the resonant frequency comparing step (2230). The resonance frequency comparing step 2230 may be a step of determining whether the receiver is the receiving apparatus or the external object.

The resonance frequency comparing step 2230 detects the peak frequency Freq _peak corresponding to the peak value using the obtained frequency characteristic and compares the peak frequency Freq _peak with the resonance frequency of the radio power transmission device compared with Freq _{offset _ thr).} The peak frequency (Freq _peak) and the resonance frequency _(resonance Freq) difference between the reception device is the error range of the critical frequency of a frequency to be determined are placed (Freq _{offset _ thr)} above (Fp- Fr> of F _{_ offset thr} ), It is determined that the external object is placed on the transmission apparatus.

This corresponds to the case of an abnormal operation, and the transmitting apparatus includes the digital pinging step 2300, the identifying and setting step 2400 and the power transmitting step 2500 for transmitting the wireless power to the receiving apparatus Do not perform.

In this case, other steps for solving the abnormal operation may be performed instead of performing each step for transmitting wireless power to the receiving device.

As an example of this, the transmitting apparatus may display it or generate a notification signal to notify the user of the abnormal operation. The transmission apparatus may transmit the notification signal to the apparatus for controlling the transmission apparatus using out-of-band communication, or may transmit the notification signal to the reception apparatus using in-band or out-of-band communication.

On the other hand, the resonance frequency in the comparison step 2230, wherein the resonance frequency _(resonance Freq) which the receiving device is a critical frequency range of the frequency error to determine that placed (Freq _{offset _ thr)} or less (Fp- Fr difference < If the _offset F _{_ thr),} it is determined that the transmission device is the receiving device is placed.

This corresponds to the case of normal operation, and the transmitting apparatus includes the digital pinging step 2300, the identifying and setting step 2400 and the power transmitting step 2500 to transmit the wireless power to the receiving apparatus .

In the digital ping step 2300, the wireless power transmission apparatus forms a wireless power signal for detecting the wireless power receiving apparatus 200, and wirelessly transmits the wireless power, which is modulated by the wireless power receiving apparatus 200 Demodulates the power signal, and obtains a power control message in the form of digital data corresponding to the response to the detection signal from the demodulated radio power signal. The wireless power transmission apparatus can recognize the wireless power receiving apparatus 200 that is a target of power transmission by receiving a power control message corresponding to a response to the detection signal.

The identifying and setting step 2400 and the power transmitting step 2500 are replaced with a description of the identifying and setting state 630 and the power transmitting state 640 with reference to FIG. 13 as described above.

23A and 23B show time characteristics and frequency characteristics of the current in the transmission coil of the wireless power transmission apparatus according to the present invention, respectively.

Referring to FIG. 20 and FIG. 23A, a predetermined time (? T2 = T2 - T0) for obtaining the frequency characteristic of the current flowing through the transmission coil 1111a is set so that a pulse width modulation signal is applied to the transmission coil 1111a Should be at least the reference time (? T1 = T1 - T0).

That is, when the pulse width modulation signal is applied to the inverter 1112 during the reference time (? T1), the current flowing in the transmission coil 1111a during the predetermined time? T2 longer than the reference time must be measured.

(TX + RX) when the receiving apparatus is placed, (TX + RX + FO) when the receiving apparatus and the external object are placed (TX + RX + FO) (TX + gap + RX) where the device is spaced apart and a case where an external object is placed (TX + FO). The frequency characteristic of the current flowing in the transmission coil 1111a is shown for a frequency band of 80 to 120 KHz according to an embodiment.

As can be seen from FIG. 23B, it can be seen that the peak frequency shifts to a frequency higher than 100 KHz, which is the resonance frequency, when an external object is placed (TX + RX + FO, TX + FO). Here, the resonance frequency is set to 100 KHz, which is the resonance frequency of the wireless power transmission apparatus (TX only), but it may be set to a frequency shifted to a frequency band lower than 100 KHz when the receiving apparatus is placed (TX + RX).

24A and 24B show the frequency characteristics of the current in the transmission coil of the wireless power transmission apparatus for the low power reception apparatus and the medium power reception apparatus. FIG. 24A shows a frequency characteristic for a low power RX device, and FIG. 24B shows a frequency characteristic for a middle power RX device.

As shown in FIG. 24A, when the external object is placed (TX + RX + FO, TX + FO), the peak frequency shifts to more than 115 KHz and the difference from 100 KHz which is the resonance frequency is large and it is easy to judge that the external object is placed Do. In addition, the peak value of the current of (TX + RX + FO, TX + FO) when the external object is placed is larger than the peak value of the current of (TX + RX, TX + gap + RX) It is easy to judge that an object is placed.

As shown in FIG. 24B, in the case of the medium power receiving apparatus, when the receiving apparatus and the external object are both placed (TX + RX + FO), the peak frequency is not so large as compared with the resonance frequency, (TX + FO) when it is placed. However, when only the external object is placed (TX + FO), the current peak value is large enough to be distinguished from the peak value of the current (TX + RX, TX + gap + RX) Of course.

Accordingly, the present invention can easily determine that an external object is placed in a wireless power transmission apparatus that performs communication with one or more wireless power receiving apparatuses.

The configuration of the wireless power transmission apparatus according to the embodiments disclosed herein may be applied to devices such as a docking station, a cradle device, and other electronic devices, May be readily apparent to those skilled in the art.

The scope of the present invention is not limited to the embodiments disclosed herein, and the present invention can be modified, changed, or improved in various forms within the scope of the present invention and the claims.

Claims (14)

A method for detecting an external object in a wireless power transmission apparatus formed to transmit power wirelessly to a wireless power receiving apparatus,
Obtaining a frequency characteristic of a current flowing in a coil in the wireless power transmission apparatus for a predetermined time;
Detecting a peak frequency corresponding to a peak value using the obtained frequency characteristic, and comparing the peak frequency with a resonant frequency of the wireless power transmission device; And
And detecting, through the comparison, whether the external object is placed on the transmission apparatus,
Wherein the step of comparing the peak frequency with the resonance frequency comprises:
Determining whether a peak value of the current at the peak frequency is equal to or greater than a second threshold value; And
Determining that the external object is placed if the difference between the peak frequency and the resonance frequency is equal to or higher than a threshold frequency that is an error range of a frequency for determining that the receiving apparatus is placed and the peak value of the current is equal to or greater than the second threshold value Wherein the method further comprises the step of detecting an external object of the wireless power transmission device. The method according to claim 1,
Prior to the step of obtaining the frequency characteristic of the current,
Transmitting an analog ping signal to the receiving device; And
And determining that the external object is not placed if the current flowing through the coil is greater than or equal to a first threshold value. The method according to claim 1,
When the low power receiving apparatus is placed in the transmitting apparatus, it is determined that the external object is placed on the transmitting apparatus when the peak frequency is equal to or higher than the threshold frequency and the peak value of the current is equal to or higher than the second threshold,
Wherein the controller determines that the external object is placed on the transmission apparatus when the peak value of the current is equal to or greater than the second threshold value when the medium power receiving apparatus is placed in the transmission apparatus. The method according to claim 1,
After the step of detecting whether the external object is laid,
Further comprising transmitting a digital ping signal to the receiving device. &Lt; Desc / Clms Page number 17 &gt; The method according to claim 1,
Wherein the current flowing through the coil is generated by pulse width modulation (PWM) applied to an inverter in the transmission apparatus. 6. The method of claim 5,
Wherein the pulse width modulation (PWM) signal is generated during a reference time, and the reference time is shorter than the predetermined time. A wireless power transmission apparatus formed to transmit power wirelessly to a wireless power receiving apparatus,
A power converter for providing a wireless power signal to the wireless power receiver; And
And a power transmission control section for controlling the wireless power signal,
The power transmission control unit
Obtaining a frequency characteristic of a current flowing in a coil in the wireless power transmission apparatus for a predetermined time;
Detecting a peak frequency corresponding to a peak value using the obtained frequency characteristic, and comparing the peak frequency with a resonant frequency of the wireless power transmission device; And
Performing a step of detecting through the comparison whether an external object is placed on the transmission apparatus,
Wherein the power transmission control unit comprises:
Determining whether a peak value of the current at the peak frequency is equal to or greater than a second threshold value; And
Determining that the external object is placed if the difference between the peak frequency and the resonance frequency is equal to or higher than a threshold frequency that is an error range of a frequency for determining that the receiving apparatus is placed and the peak value of the current is equal to or greater than the second threshold value Lt; RTI ID = 0.0 &gt; 1, &lt; / RTI &gt; 8. The method of claim 7,
The power transmission control unit
Prior to the step of obtaining the frequency characteristic of the current,
Transmitting an analog ping signal to the receiving device; And
And determining that the external object is not placed if the current flowing through the coil is equal to or greater than a first threshold value. 8. The method of claim 7,
When the low power receiving apparatus is placed in the transmitting apparatus, it is determined that the external object is placed on the transmitting apparatus when the peak frequency is equal to or higher than the threshold frequency and the peak value of the current is equal to or higher than the second threshold,
Wherein the controller determines that the external object is placed on the transmission apparatus when the peak value of the current is equal to or greater than the second threshold value when the medium power receiving apparatus is placed in the transmission apparatus. 8. The method of claim 7,
After the step of detecting whether the external object is laid,
Further comprising the step of transmitting a digital ping signal to the receiving device. 8. The method of claim 7,
Wherein a current flowing through the coil is generated by pulse width modulation (PWM) applied to an inverter in the transmission apparatus. 12. The method of claim 11,
The power conversion unit
And a coil formed to convert the current into magnetic flux. 13. The method of claim 12,
The power conversion unit
And a capacitor disposed between the coil and the inverter and configured to generate the resonant frequency based on an inductance of the coil and its capacitance. 14. The method of claim 13,
The power conversion unit
And an inverter coupled to the capacitor to convert the DC input from the power supply to an AC waveform and to generate and transmit the pulse width modulated signal to the coil for a reference time,
And the reference time is shorter than the predetermined time.

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