KR20200084571A - Method and apparatus for transmitting wireless power - Google Patents

Abstract

The present invention relates to a method and a device for transmitting wireless power. According to an embodiment of the present invention, the method for transmitting wireless power of a wireless power transmitter comprises the steps of: setting resonance efficiency to a minimum and detecting an object disposed in a charging area; and, when the object is detected, increasing the resonance efficiency in stages until a response signal from a wireless power receiver is received. Therefore, the present invention has an advantage of enabling safe charging regardless of a separation distance between transceivers in a resonance type wireless charging system.

Description

Method and apparatus for transmitting wireless power

The present invention relates to a wireless charging technology, and more particularly, to a wireless power transmission method and an apparatus therefor for safe charging regardless of the separation distance between transceivers in a resonant wireless power transmission system.

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

In order for information communication devices to be accessed anytime, anywhere, sensors in a computer chip with a communication function must be installed in all facilities of society. Therefore, the problem of supplying power to these devices and sensors has become a new task. In addition, as the types of mobile devices, such as Bluetooth handsets and iPods, as well as mobile phones, have rapidly increased, charging the battery has required time and effort from users. As a method of solving such a problem, a wireless power transmission technology has recently received attention.

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

To date, the energy transmission method using wireless can be largely classified into an electromagnetic induction method, an electromagnetic resonance method, and an RF transmission method using a short-wavelength radio frequency.

The electromagnetic induction method is a technology that uses the phenomenon that the magnetic flux generated at this time causes electromotive force in another coil when two coils are adjacent to each other and then a current flows through one coil, and is rapidly commercialized around small devices such as mobile phones. Is going on. The electromagnetic induction method can transmit power from a few watts (W) to hundreds of kilowatts (kW) and is highly efficient, but has the disadvantage that the maximum transmission distance-that is, the maximum separation distance of a rechargeable transceiver is less than 1 centimeter (cm). have.

The electromagnetic resonance method has an advantage in that a wireless transceiver can be wirelessly charged at a longer distance than the electromagnetic induction method by maximizing efficiency by using a resonant frequency.

However, since the electromagnetic resonance method uses a resonance frequency that is the maximum efficiency, the output power of the transmitter is high. Accordingly, overpower may be transmitted to a receiver approaching a close distance. If power is received by the receiver beyond the limits of the receiver components, the receiver may be damaged.

Particularly, in the case of the resonant wireless charging system, when the transmitter and receiver match the resonance frequency, a large output is generated at a small input current, so if the separation distance between the transmitting and receiving periods is short, damage to the receiver may occur through a general closed-loop power control procedure. There was a problem difficult to prevent.

The present invention is designed to solve the problems of the above-described prior art, and an object of the present invention is to provide a method and apparatus for transmitting wireless power for a resonant wireless charging system.

Another object of the present invention is to provide a wireless power transmission method and an apparatus therefor for safe charging regardless of the separation distance between transceivers in a resonant wireless power transmission system.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those having ordinary knowledge in the technical field to which the present invention belongs from the following description. Will be able to.

The present invention can provide a method and apparatus for transmitting wireless power.

In the wireless power transmission method of the wireless power transmitter according to the embodiment, the resonance efficiency is set to the lowest level to detect an object disposed in the charging area, and when the object is detected, resonance until a response signal from the wireless power receiver is received It may include the step of increasing the efficiency step by step.

For example, the resonance efficiency may be set by adjusting the capacitance of a resonance circuit provided in the wireless power transmitter.

As another example, the resonance efficiency may be set by adjusting the inductance of the resonance circuit provided in the wireless power transmitter.

As another example, the resonance efficiency may be set by adjusting the capacitance and inductance of the resonance circuit provided in the wireless power transmitter.

In the wireless power transmission method of the wireless power transmitter, when the response signal is received, connecting the communication to receive information on the required power from the wireless power receiver and performing closed loop power control based on the requested power In addition, if the required power cannot be supplied through the closed-loop power control, the resonance efficiency may be gradually increased until the required power can be supplied.

In addition, the wireless power transmission method of the wireless power transmitter includes receiving information about V_RECT, which is the rectifier output voltage of the wireless power receiver, and if the V_RECT is less than or equal to a second reference during the closed loop power control, the resonance efficiency is improved. It can be increased in stages.

In addition, the wireless power transmission method of the wireless power transmitter includes the step of reducing the resonance efficiency step by step if the V_RECT exceeds the first criterion during the closed-loop power control, the first criterion than the second criterion It can be large.

In addition, the wireless power transmission method of the wireless power transmitter includes stopping the wireless power transmission when the V_RECT exceeds a predetermined upper limit during the closed-loop power control, and the upper limit may be a value greater than the first reference.

In addition, if the response signal is not received until the resonance efficiency is maximized, power transmission may be stopped for a predetermined time after outputting a warning alarm.

The wireless power transmitter according to another embodiment includes a transmission coil transmitting wireless power and a communication antenna transmitting and receiving a wireless signal, a modem processing a signal transmitted and received through the communication antenna, and a resonance efficiency control circuit for setting resonance efficiency and the And a transmission controller that controls the resonance efficiency control circuit, until the transmission controller sets the resonance efficiency to the minimum to detect an object disposed in the charging area, and receives a response signal from the wireless power receiver through the modem. The resonance efficiency can be increased step by step.

Also, the resonance efficiency may be set by adjusting the capacitance of the resonance efficiency control circuit.

In addition, when the response signal is received, the transmission controller connects communication with the wireless power receiver to receive information on required power from the wireless power receiver, and performs closed-loop power control based on the requested power. .

In addition, the wireless power transmitter further includes an inverter that generates an AC power signal based on a driving voltage and a reference signal, and the transmission controller controls the duty and/or phase of the reference signal during the closed-loop power control. The strength of the wireless power can be adjusted.

In addition, if it is impossible to supply the required power through the closed-loop power control, the transmission controller may increase the resonance efficiency step by step until the requested power can be supplied.

In addition, when the transmission controller receives information on V_RECT, which is the rectifier output voltage of the wireless power receiver during the closed-loop power control, and the V_RECT is less than or equal to a second reference, the resonance efficiency may be increased stepwise.

In addition, when the transmission controller exceeds the first criterion, which is a value greater than the second criterion, during the closed loop power control, the resonance efficiency may be reduced stepwise.

In addition, when the V_RECT of the closed-loop power control exceeds a predetermined upper limit that is a value greater than the first reference, the transmission controller may stop transmitting the wireless power.

In addition, if the response signal is not received until the resonance efficiency is maximized, the transmission of the wireless power may be stopped for a predetermined time after outputting a warning alarm provided with the transmission controller.

Another embodiment of the present invention can provide a computer-readable recording medium recording a program for executing any one of the wireless power transmission methods.

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

When explaining the effect on the method and apparatus according to the present invention are as follows.

The present invention has an advantage of providing a method and apparatus for transmitting wireless power for a resonant wireless charging system.

In addition, the present invention provides a wireless power transmission method and a device therefor for safe charging regardless of the separation distance between transceivers in a resonant wireless power transmission system.

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

The accompanying drawings are provided to help understanding of the present invention, and provide embodiments of the present invention with detailed description. However, the technical features of the present invention are not limited to specific drawings, and features disclosed in each drawing may be combined with each other to form a new embodiment.
1 is a block diagram illustrating a wireless charging system according to an embodiment.
2 is a block diagram illustrating the structure of a resonant wireless power transmission system according to an embodiment.
3 is a block diagram illustrating the structure of a wireless power transmitter according to an embodiment.
4 is a view for explaining the structure of the resonant circuit control circuit of the embodiment of FIG. 3.
FIG. 5 is a block diagram illustrating a structure of a wireless power receiver interworking with the wireless power transmitter according to FIG. 3.
6 is a state transition diagram of a wireless power receiver supporting an electromagnetic resonance method according to an embodiment.
7 is a view for explaining a state transition procedure of a wireless power transmitter that supports an electric resonance method according to an embodiment.
8 is a view for explaining a resonance frequency and an operating frequency in an inductive wireless charging method.
9 is a view for explaining a minimum distance between the transceiver and the resonance frequency change according to the combination of capacitances of the resonance circuit of the embodiment.
10 is a flowchart illustrating a method for transmitting wireless power in a resonant wireless power transmitter according to an embodiment.
11 is a flowchart illustrating a method for transmitting wireless power in a resonant wireless power transmitter according to an embodiment.
12 is a flowchart illustrating a method for transmitting wireless power in a resonant wireless power transmitter according to another embodiment.
13 is a view for explaining a method of controlling wireless power of a wireless power transmitter according to an embodiment.

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

In the above, even if all the components constituting the embodiment of the present invention are described as being combined or operated as one, the present invention is not necessarily limited to these embodiments. That is, if it is within the scope of the present invention, all of the components may be selectively combined and operated. In addition, although all of the components may be implemented by one independent hardware, a part or all of the components are selectively combined to perform a part or all of functions combined in one or a plurality of hardware. It may be implemented as a computer program having a. The codes and code segments constituting the computer program can be easily deduced by those skilled in the art of the present invention. Such a computer program is stored in a computer readable storage medium (Computer Readable Media) to be read and executed by a computer, thereby implementing an embodiment of the present invention. The storage medium of the computer program may include a magnetic recording medium, an optical recording medium, and the like.

In the description of the embodiment, when described as being formed in the "top (top) or bottom (bottom)", "before (front) or after (back)" of each component, "top (top) or bottom "Bottom" and "before (before) or after (behind)" include both two components in direct contact with each other or one or more other components formed between two components.

In addition, the terms "include", "consist" or "have" as described above mean that the component can be inherent, unless specifically stated otherwise, to exclude other components. It should not be interpreted as being able to further include other components. All terms, including technical or scientific terms, have the same meaning as generally understood by a person skilled in the art to which the present invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted as being consistent with the meaning in the context of the related art, and are not to be interpreted as ideal or excessively formal meanings unless explicitly defined in the present invention.

In addition, in describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the component from other components, and the nature, order, or order of the component is not limited by the term. When a component is described as being "connected", "coupled" or "connected" to another component, the component may be directly connected to or connected to the other component, but another component between each component It should be understood that elements may be "connected", "coupled" or "connected".

In the description of the embodiment, an apparatus for transmitting wireless power on a wireless power system includes a wireless power transmitter, a wireless power transmitter, a wireless power transmitter, a wireless power transmitter, a transmitter, a transmitter, a transmitter, a transmitter, for convenience of explanation, A wireless power transmitter, a wireless power transmitter, and the like will be used in combination.

In addition, a wireless power receiving device, a wireless power receiver, a wireless power receiving device, a wireless power receiver, a receiving terminal, a receiving side, a receiving device, a receiver for convenience of description as an expression for a device receiving wireless power from the wireless power transmitting device Etc. can be used interchangeably.

The wireless power transmitter according to the embodiment may be configured in a pad shape, a cradle shape, an AP (Access Point) shape, a small base station shape, a stand shape, a ceiling embedded shape, a wall-mounted shape, a vehicle embedded shape, a vehicle mounted shape, etc., one The transmitter of can transmit power to a plurality of wireless power receiving devices at the same time.

To this end, the wireless power transmitter may provide at least one wireless power transmission scheme, including, for example, an electromagnetic induction scheme, an electromagnetic resonance scheme, and the like.

For example, in the wireless power transmission method, various radio power transmission standards based on an electromagnetic induction method that generates a magnetic field in a coil of a power transmitting end and charges it using an electromagnetic induction principle in which electricity is induced in a coil in a receiving end under the influence of the magnetic field may be used. . Here, the electromagnetic induction wireless power transmission standard may include a wireless charging technology of an electromagnetic induction type defined by a Wireless Power Consortium (WPC) or/and a Power Matters Alliance (PMA).

As another example, an electromagnetic resonance method in which power is transmitted to a wireless power receiver located at a short distance by tuning a magnetic field generated by a transmission coil of the wireless power transmitter to a specific resonance frequency may be used. As an example, the electromagnetic resonance method may include a wireless charging technique of a resonance method defined by A4WP (Alliance for Wireless Power), a standard organization for wireless charging technology.

As another example, an RF wireless power transmission method may be used in which wireless power transmission method transmits power to a wireless power receiver located at a long distance by applying low power energy to an RF signal.

As another example, the wireless power transmitter according to the present invention may be designed to support at least two or more wireless power transmission methods among the above-described electromagnetic induction method, electromagnetic resonance method, and RF wireless power transmission method.

In this case, the wireless power transmitter is not only a wireless power transmission method that can be supported by the wireless power transmitter and the wireless power receiver, but also a wireless power transmission method to be adaptively used for the corresponding wireless power receiver based on the type, state, and required power of the wireless power receiver. Can decide.

In addition, the wireless power receiver according to the embodiment may be provided with at least one wireless power transmission scheme, and may simultaneously receive wireless power from two or more wireless power transmitters. Here, the wireless power transmission method may include at least one of the electromagnetic induction method, the electromagnetic resonance method, and the RF wireless power transmission method.

The wireless power receiver according to the present invention is a mobile phone, a smart phone, a laptop computer, a terminal for digital broadcasting, PDA (Personal Digital Assistants), PMP (Portable Multimedia Player), navigation, MP3 player , Electric toothbrush, electronic tag, lighting device, remote control, may be mounted on a small electronic device such as a fishing boat, but is not limited to this, and is equipped with a wireless power receiving means according to the present invention, it is sufficient if the battery can be charged. The wireless power receiver according to another embodiment of the present invention may be mounted in a vehicle, an unmanned aerial vehicle, an air drone, and the like.

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

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

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

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

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

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

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

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

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

The wireless power receiver 20 according to an embodiment of the present invention may acquire various status information of the electronic device 30. For example, the status information of the electronic device 30 may include current power usage information, information for identifying a running application, CPU usage information, battery charging status information, battery output voltage/current information, etc., but is not limited thereto. If not, it is sufficient if the information can be obtained from the electronic device 30 and can be used for wireless power control.

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

The wireless power receiver 20 may notify the electronic device 30 when it is determined that the connected wireless power transmitter 10 supports the fast charging mode. The electronic device 30 may indicate that fast charging is possible through a predetermined display means provided, for example, a liquid crystal display.

2 is a block diagram illustrating the structure of a resonant wireless power transmission system according to an embodiment.

Referring to FIG. 2, a resonant wireless power transmission system may include a wireless power transmitter 100 and a wireless power receiver 200.

In FIG. 2, the wireless power transmitter 100 is shown to transmit power wirelessly to one wireless power receiver 200 through resonant coupling, but this is only one embodiment, and another embodiment The wireless power transmitter 100 according to may transmit wireless power to the plurality of wireless power receivers 200.

It should be noted that the wireless power receiver 200 according to another embodiment may simultaneously receive wireless power from a plurality of wireless power transmitters 100.

The wireless power transmitter 100 generates an electromagnetic field of a specific frequency, and the wireless power receiver 200 can absorb the electromagnetic field and receive power.

In general, the resonant wireless power receiver 100 may receive power by tuning to the same frequency that the wireless power transmitter 100 uses for power transmission.

That is, the output power of the wireless power transmitter 100 may be transmitted to the wireless power receiver 200 having a resonance coupling with the wireless power transmitter 100.

The maximum number of wireless power receivers 200 that can receive power from one wireless power transmitter 100 is the maximum transmission power level of the wireless power transmitter 100, the maximum power reception level of the wireless power receiver 200, the wireless It may be determined based on the physical structures of the power transmitter 100 and the wireless power receiver 200.

The wireless power transmitter 100 and the wireless power receiver 200 may perform bidirectional communication using a frequency band different from a frequency band used for wireless power transmission, that is, a resonant frequency band.

For example, a two-way communication may use a half-duplex Bluetooth Low Energy (BLE) communication protocol.

The wireless power transmitter 100 and the wireless power receiver 200 may exchange characteristic information and status information of each other, that is, power negotiation information, through bidirectional communication.

For example, the wireless power receiver 200 may transmit predetermined power reception state information for controlling the power level received from the wireless power transmitter 100 to the wireless power transmitter 100 through bidirectional communication. 100) may dynamically control the transmission power level based on the received power reception state information.

The wireless power transmitter 100 can not only provide power required by the wireless power receiver 200, but also a device or load due to over-voltage/over-current/over-heat. A function for preventing damage, a function for preventing unnecessary power from being wasted according to under-voltage can be provided.

In addition, the wireless power transmitter 100 has a function of authenticating and identifying the wireless power receiver 100 through two-way communication, an incompatible device, or an object that cannot be charged, that is, a function of identifying a foreign object. It is also possible to perform functions such as identifying a load.

Hereinafter, a wireless power transmission process in a resonant wireless power transmission system will be described in more detail.

The wireless power transmitter 100 includes a power supply unit 110, a power conversion unit 120, a matching circuit 130, a transmission resonator 140, and a main controller , 150) and a communication unit (Communication Unit 160).

The power supply unit 110 may supply a specific supply voltage to the power conversion unit 120 under the control of the main control unit 150. At this time, the supply voltage may be a DC voltage or an AC voltage.

The power conversion unit 210 may convert the voltage received from the power supply unit 110 to a specific voltage under the control of the main control unit 150.

To this end, the power converter 210 may include at least one of a DC/DC converter, an AC/DC converter, a power amplifier, an inverter, and a switching mode power supply (SMPS).

The matching circuit 130 is a circuit that matches the impedance between the power converter 210 and the transmission resonator 140 to maximize power transmission efficiency.

The transmission resonator 140 may transmit power wirelessly using a specific resonance frequency according to the voltage applied from the matching circuit 130.

The wireless power receiver 100 includes a reception resonator (210), a rectifier (220), a DC-DC converter (DC-DC converter, 230), a load (240), and a main controller (250). ) And a communication unit (Communication Unit, 260).

The reception resonator 210 may wirelessly receive power output by the transmission resonator 140 through a resonance phenomenon.

The rectifier 210 may convert the AC voltage applied from the receiving resonator 210 into a DC voltage.

The DC-DC converter 230 may convert the rectified DC voltage into a specific DC voltage required by the load 240.

The main control unit 250 may control the operation of the rectifier 220 and the DC-DC converter 230 or generate characteristics and status information of the wireless power receiver 200 and transmit them to the communication unit 260.

For example, the main control unit 250 may control the operation of the rectifier 220 and the DC-DC converter 230 by monitoring the intensity of the output voltage and current from the rectifier 220 and the DC-DC converter 230. have.

The monitored output voltage and current intensity information may be transmitted in real time to the wireless power transmitter 100 through the communication unit 260.

In addition, the main control unit 250 compares the rectified DC voltage with a predetermined reference voltage to determine whether it is an over-voltage state (Over-Voltage State) or an under-voltage state (Under-Voltage State), and a predetermined system error state according to the determination result. When detected, the detection result may be transmitted to the wireless power transmitter 100 through the communication unit 260.

In addition, when the system error condition is detected, the main control unit 250 controls the operation of the rectifier 220 and the DC-DC converter 230 to prevent damage to the load, or a predetermined overcurrent including a switch or (and) zener diode. It is also possible to control the power humanized to the load 240 using a blocking circuit.

3 is a block diagram illustrating the structure of a wireless power transmitter according to an embodiment.

Referring to FIG. 3, the wireless power transmitter 300 includes a transmission coil 310, a resonance efficiency control circuit 320, an inverter 330, a communication antenna 340, a modem 350 and a transmission controller 360 Can be configured.

The signal received through the communication antenna 340 may be demodulated by the modem 350 and transmitted to the transmission controller 360. When there is a message to be transmitted to the wireless power receiver, the transmission controller 360 transmits the message to the modem 350, and the modem 350 modulates the message received from the transmission controller 360 to the communication antenna 340. Can transmit.

The inverter 330 may generate an AC power signal based on the driving DC voltage V-Rail and a reference signal applied from the transmission controller 360.

Here, the reference signal may be a pulse width modulation (PWM) signal. The number of PWM signals applied to the inverter 330 may be determined according to the type of the inverter 330, that is, the number of switches provided in the inverter 330.

For example, if the inverter 330 is a half-bridge type, the number of PWM signals is 2, and if the inverter 330 is a full-bridge type, the number of PWM signals may be 4. .

The transmission controller 360 may control the strength of the AC power signal by controlling at least one of a duty and a phase of the reference signal.

The output of the inverter 330 may be applied to the transmission resonance circuit 370.

The transmission controller 360 may control the resonance efficiency of the transmission resonance circuit 370.

For example, the transmission controller 360 may control a resonance efficiency by transmitting a predetermined control signal to the resonance efficiency control circuit 320.

The resonance efficiency control circuit 320 may set resonance efficiency by controlling a switch provided according to a control signal received from the transmission controller 360.

For example, the resonance efficiency control circuit 320 may adjust the capacitance of the transmission resonance circuit 370 according to a control signal received from the transmission controller 360.

As another example, the resonance efficiency control circuit 320 may adjust the inductance of the transmission resonance circuit 370 according to the control signal received from the transmission controller 360.

In another embodiment, the resonance efficiency control circuit 320 may adjust the capacitance and inductance of the transmission resonance circuit 370 according to the control signal received from the transmission controller 360.

The transmission controller 360 can dynamically move the resonance frequency by controlling the resonance efficiency control circuit 320.

When the resonant frequency at the transmitting end moves, the resonant coupling state between the transmitting end and the receiving end-that is, the coupling coefficient-can be dynamically changed. The strength of power received by the wireless power receiver may also be changed according to a change in the resonance coupling state.

The resonant wireless power transmission system has an advantage of being capable of remote wireless charging when compared to the inductive wireless power transmission system.

That is, higher wireless power transmission is required for wireless charging over a longer distance. To this end, the resonant wireless power transmission system uses a resonance frequency capable of maximum power transmission.

On the other hand, since the inductive wireless power transmission system is designed for the purpose of proximity wireless charging, an operating frequency is used instead of a resonant frequency capable of maximum power transmission.

The frequency bands used for the resonant wireless power transmission system and the inductive wireless power transmission system will become clearer through the description of FIG. 8 to be described later.

The transmission controller 360 may be controlled to have a controllable minimum resonance efficiency during initial power transmission in order to prevent damage to a wireless power receiver that is too close by a high AC power signal.

When the wireless power receiver is identified with the minimum resonance efficiency after object detection, the transmission controller 360 may start charging based on the currently set minimum resonance efficiency.

On the other hand, if the wireless power receiver is not identified with the minimum resonance efficiency after object detection, the transmission controller 360 may increase the resonance efficiency step by step until the wireless power receiver is identified.

The transmission controller 360 may adjust the strength of the AC power signal output by the inverter 330 based on the receiver status information received through the modem 350.

In addition, the transmission controller 360 may dynamically control the resonance efficiency of the transmission resonance circuit 370 based on the receiver state information received through the modem 350.

Here, the receiver state information may include V_RECT, which is a voltage measured at the rear end of the rectifier of the wireless power receiver, but is not limited thereto.

The transmission controller 360 according to the embodiment may dynamically control the resonance efficiency such that V_RECT is equal to or less than a predetermined first reference.

In addition, the transmission controller 360 according to the embodiment may dynamically control the resonance efficiency such that V_RECT is equal to or greater than a predetermined second reference. Here, the first criterion may be set larger than the second criterion.

The transmission controller 360 according to an embodiment may dynamically control resonance efficiency so that V_RECT maintains an appropriate voltage level. For example, an appropriate voltage level may be larger than the second reference and smaller than the first reference.

In the embodiment of FIG. 3, the transmission controller 360 is described as transmitting the PWM signal to the inverter 330, but this is only one embodiment, and the wireless power transmitter according to another embodiment is the transmission controller 360 ) And a gate driver (not shown) disposed between the inverter 330.

In this case, the transmission controller 360 provides a reference clock signal to the gate driver, and the gate driver can generate a PWM signal using the reference clock signal. The PWM signal generated by the gate driver may be applied to the inverter 330.

The wireless power transmitter 300 according to the embodiment may further include a memory (not shown) in which a capacitance mapping table for setting resonance efficiency for each step is stored.

The transmission controller 360 may control the resonance efficiency control circuit 320 by referring to the capacitance mapping table.

An example of the capacitance mapping table will be clarified through the description of FIG. 9 to be described later.

4 is a view for explaining the structure of the resonant circuit control circuit of the embodiment of FIG. 3.

Referring to FIG. 4, the resonant circuit adjustment circuit 320 may include first to Nth resonant capacitors 410 and first to Nth switches 420 for activating/deactivating each resonant capacitor. .

The transmission controller 360 of FIG. 3 may control the capacitances of the transmission resonance circuit 370 by controlling the first to Nth switches 420 to set a specific resonance efficiency.

The transmission controller 360 may adjust the capacitance by turning on at least one of the first to Nth switches 420.

FIG. 5 is a block diagram illustrating a structure of a wireless power receiver interworking with the wireless power transmitter according to FIG. 3.

Referring to FIG. 5, the wireless power receiver 500 includes a reception resonance circuit 510, a rectifier 520, a DC/DC converter (530), a blocking circuit 540, a load 550, and a sensor 560, a communication antenna 570, a modem 580, and a receiving controller 590.

The signal received through the communication antenna 570 may be demodulated by the modem 580 and transmitted to the reception controller 590. When there is a message to be transmitted to the wireless power transmitter 300, the reception controller 360 transmits the message to the modem 580, and the modem 580 modulates the message received from the reception controller 590 to communicate with the communication antenna ( 570).

The wireless power receiver 500 shown in the example of FIG. 5 described above may exchange information with the wireless power transmitter 300 through in-band communication.

The reception resonant circuit 510 may include an inductor and at least one capacitor.

The AC power transmitted by the wireless power transmitter 300 may be transmitted to the rectifier 520 through the reception resonance circuit 510. The rectifier 520 may convert AC power received through the reception resonant circuit 510 into DC power and transmit it to the DC/DC converter 530.

The DC/DC converter 530 may convert the intensity of the output DC power of the rectifier 520 to DC power at a specific intensity required by the load 550.

The sensor 560 measures the output DC power intensity of the rectifier 520-that is, V_RECT-and transmits the measurement result to the receiving controller 590.

The reception controller 590 may perform closed-loop power control based on the output DC power V_RECT of the rectifier 520. To this end, the reception controller 590 may transmit receiver status information including at least V_RECT information to the wireless power transmitter 300 through the modem 580.

In addition, the sensor 560 may measure the intensity of the current flowing through the reception resonant circuit 510 according to wireless power reception, and may transmit the measurement result to the reception controller 590.

Also, the sensor 560 may measure the internal temperature of the wireless power receiver 500 or an electronic device equipped with the wireless power receiver 500, and provide information regarding the measured temperature to the reception controller 590.

For example, the reception controller 590 may determine whether an overvoltage occurs by comparing the measured intensity of the output DC power V_RECT with a predetermined reference value. As a result of the determination, when an overvoltage is generated, the reception controller 590 may transmit a predetermined packet indicating that the overvoltage has occurred to the wireless power transmitter 300 through the modem 580.

The reception controller 590 may be booted and driven when V_RECT is greater than or equal to a predetermined reference value.

When the measured internal temperature exceeds a predetermined reference value, the reception controller 590 may control the blocking circuit 540 so that the output DC power of the DC/DC converter 530 is not transmitted to the load 550. Here, the reception controller 590 may transmit the power transmission interruption packet including the overheating code to the wireless power transmitter 300 through the modem 580.

The reception controller 590 may be linked with a power management element (not shown) that controls the internal power of an electronic device equipped with the wireless power receiver 500-for example, a PMIC (Power Management IC).

In this case, the output DC power of the DC/DC converter 530 may be transmitted to the power management element through the blocking circuit 540, and the power management element may control battery charging and power supply to the internal components of the electronic device. have.

The power management element may provide battery charge state information to the receiving controller 590. The reception controller 590 may determine whether charging is in progress based on the battery charge state information and the internal temperature information.

The reception controller 590 may control the blocking circuit 540 based on the sensing information received from the sensor 560.

For example, the sensing information is measured in correspondence to at least one of rectifier output voltage information, current intensity information flowing through the receiving resonant circuit 510, a load or (and) a wireless power receiver or a device equipped with a wireless power receiver. Temperature information.

For example, when the rectifier output voltage exceeds a predetermined reference value, the receiving controller 580 may turn off a switch (not shown) provided in the blocking circuit 540 to cut off power transmitted to the load 550.

As another example, the blocking circuit 540 may be provided with a voltage absorbing element—eg, a zener diode—in this case, if the output voltage of the rectifier 520 exceeds a reference value, the voltage exceeding the reference value absorbs the voltage. The voltage absorbed by the device and corresponding to the reference value may be transmitted to the load 550.

6 is a state transition diagram of a wireless power receiver supporting an electromagnetic resonance method according to an embodiment.

Referring to Figure 6, the state of the wireless power receiver is largely disabled state (Disable State, 610), boot state (Boot State, 620), enabled state (Enable State, 630) (or On state) and system error state ( System Error State, 640).

At this time, the state of the wireless power receiver may be determined based on the intensity of the output voltage at the rectifier end of the wireless power receiver-hereinafter referred to as a V _RECT business card-for convenience of description.

The activation state 630 may be divided into an optimal voltage state (Optimum Voltage State, 631), a low voltage state (Low Voltage State, 632), and a high voltage state (High Voltage State, 633) according to the value of V _RECT .

The wireless power receiver in the deactivated state 610 may transition to the boot state 620 if the measured V _RECT value is greater than or equal to a predefined V _{RECT_BOOT} value.

In the boot state 620, the wireless power receiver may establish an out-of-band communication link with the wireless power transmitter and wait until the V _RECT value reaches the power required by the load end.

When it is confirmed that the V _RECT value has reached the power required for the load stage, the wireless power receiver in the boot state 620 may transition to the activated state 630 to start charging.

The wireless power receiver in the activated state 630 may transition to the boot state 620 when it is confirmed that charging is completed or charging is stopped.

In addition, when a predetermined system error is detected, the wireless power receiver in the activated state 630 may transition to the system error state 640. Here, the system error may include overvoltage, overcurrent, and overheat, as well as other predefined system error conditions.

In addition, the wireless power receiver in the activated state 630 may transition to the deactivated state 610 when the V _RECT value falls below the V _{RECT_BOOT} value.

In addition, the wireless power receiver in the boot state 620 or the system error state 640 may transition to the deactivated state 610 when the V _RECT value falls below the V _{RECT_BOOT} value.

The activation state 630 may be divided into a low voltage state (632), an optimal voltage state (Optimum Voltage State, 631), and a high voltage state (High Voltage State, 633) according to the value of V _RECT .

The low voltage state 632 means a state in which V _{RECT_BOOT} <= V _RECT <= V _{RECT_MIN} , the optimal voltage state 631 means a state in which V _{RECT_MIN} <V _RECT <=V _{RECT_HIGH} , and the high voltage state 633 V _{RECT_HIGH} <V _RECT <= V _{RECT_MAX} .

In particular, the wireless power receiver transitioned to the high voltage state 633 may reserve the operation of cutting off the power supplied to the load during a predetermined time-a high voltage state holding time for convenience of description below.

Here, the high voltage state maintenance time may be determined in advance so as not to cause damage to the wireless power receiver and the load in the high voltage state 633.

When the wireless power receiver transitions to the system error state 640, a predetermined message indicating overvoltage generation may be transmitted to the wireless power transmitter through an out-of-band communication link within a predetermined time.

In addition, the wireless power receiver may control the voltage applied to the load by using the overvoltage blocking means provided to prevent damage to the load due to overvoltage in the system error state 630. Here, an ON/OFF switch or/and a zener diode may be used as the overvoltage blocking means.

Although the above embodiment describes a method and means for responding to a system error in the wireless power receiver when an overvoltage is generated in the wireless power receiver and transitions to the system error state 640, this is only one embodiment, and the present invention Another embodiment may transition to a system error state by overheating, overcurrent, or the like in the wireless power receiver.

For example, when the system transitions to a system error state due to overheating, the wireless power receiver may transmit a predetermined message informing the occurrence of overheating to the wireless power transmitter.

At this time, the wireless power receiver may reduce the heat generated inside by driving a cooling fan or the like.

The wireless power receiver according to another embodiment of the present invention may receive wireless power in conjunction with a plurality of wireless power transmitters. In this case, the wireless power receiver may transition to the system error state 640 when it is determined that the wireless power transmitter determined to receive the actual wireless power is different from the wireless power transmitter configured with the actual out-of-band communication link.

7 is a view for explaining a state transition procedure of a wireless power transmitter that supports an electric resonance method according to an embodiment.

Referring to Figure 7, the state of the wireless power transmitter is largely configured state (Configuration State, 710), power saving state (Power Save State, 720), low power state (Low Power State, 730), power transfer state (Power Transfer State) , 740), a local fault state (750), and a locking fault state (Latching Fault State, 760).

When power is applied to the wireless power transmitter, the wireless power transmitter may transition to the configuration state 710. The wireless power transmitter may transition to the power saving state 720 when a predetermined reset timer expires in the configuration state 710 or the initialization procedure is completed.

Upon entering the power saving state 720, the wireless power transmitter may generate a beacon sequence.

The wireless power transmitter may control the beacon sequence to be initiated within a predetermined time after entering the power saving state 720.

For example, the wireless power transmitter may control the beacon sequence to be initiated within 50 ms after transitioning from the configuration state 710 to the power saving state 720, but is not limited thereto.

In the power saving state 720, the wireless power transmitter generates and transmits a first beacon sequence for detecting a wireless power receiver at regular intervals, and detects an impedance change, that is, load variation. can do. Hereinafter, for convenience of description, the first beacon and the first beacon sequence will be referred to as Short Beacon and Short Beacon sequences, respectively.

The short beacon sequence means a transmission pattern of a low power beacon signal for an object disposed in a charging area to detect.

The short beacon sequence is repeatedly generated at a certain time interval (tCYCLE) for a short period (tSHORT_BEACON), so it is a low-power non-continuous signal, and thus, standby power consumption can be minimized.

For example, tSHORT_BEACON may be set to 30 ms or less, and tCYCLE to 250 ms ±5 ms, respectively. In addition, the current intensity of the short beacon should be greater than or equal to a predetermined reference value, and may increase gradually over a period of time.

The wireless power transmitter may be provided with a predetermined sensing means for detecting a change in reactance and resistance in a reception resonator according to the short beacon.

Further, in the power saving state 720, the wireless power transmitter may periodically generate and transmit a second beacon sequence for supplying sufficient power required for booting and responding to the wireless power receiver. Hereinafter, for convenience of description, the second beacon and the second beacon sequence will be referred to as Long Beacon and Long Beacon sequences, respectively.

The wireless power receiver may be booted using power received through the second beacon sequence, and may broadcast a predetermined response signal through an out-of-band communication channel after booting.

The Long Beacon sequence may be generated and transmitted at a predetermined time interval (t _{LONG_BEACON_PERIOD} ) for a relatively long period (t _{LONG_BEACON} ) compared to the Short Beacon to supply sufficient power for booting the wireless power receiver.

For example, t _{LONG_BEACON} may be set to 105 ms+5 ms and t _{LONG_BEACON_PERIOD} to ₈₅₀ ms, respectively, and the current strength of the long beacon may be relatively strong compared to the current strength of the short beacon. In addition, in the Long Beacon, power of a certain strength may be maintained during a transmission period.

Thereafter, when the impedance change of the reception resonator is sensed, the wireless power transmitter may initiate a Long Beacon sequence and wait for the reception of a predetermined response signal while transmitting the Long Beacon.

As an example, the response signal may be an advertisement signal. For convenience of description below, the response signal for the Long Beacon will be referred to as an advertisement signal or advertisement signal. Here, the wireless power receiver may broadcast an advertisement signal through an out-of-band communication frequency band different from the resonance frequency band.

As an example, the advertisement signal may include message identification information for identifying a message defined in a corresponding out-of-band communication standard, a unique service or wireless power receiver identification for identifying whether the wireless power receiver is a legitimate or compatible receiver for the wireless power transmitter. Information, output power information of the wireless power receiver, rated voltage/current information applied to the load, antenna gain information of the wireless power receiver, information for identifying the category of the wireless power receiver, wireless power receiver authentication information, and overvoltage protection It may include at least one of information on whether or not software version information mounted on the wireless power receiver.

Upon receiving the advertisement signal, the wireless power transmitter may attempt to connect an out-of-band communication with the wireless power receiver after transitioning from the power saving state 720 to the low power state 730.

Subsequently, the wireless power transmitter may perform a predetermined registration procedure for the wireless power receiver identified through the established out-of-band communication link.

For example, when the out-of-band communication is a Bluetooth low power communication, the wireless power transmitter performs Bluetooth pairing with the wireless power receiver and can exchange at least one of each other's status information, characteristic information, and control information through the paired Bluetooth link. have.

If the wireless power transmitter transmits to the wireless power receiver a predetermined control signal for initiating charging through out-of-band communication in the low power state 730, i.e., a predetermined control signal that the wireless power receiver requests to deliver power to the load, The wireless power transmitter may transition from a low power state 730 to a power transmission state 740.

If, in the low power state 730, the out-of-band communication link setting procedure or registration procedure is not normally completed, the wireless power transmitter may transition from the low power state 730 to the power saving state 720.

The wireless power transmitter may drive a separate separate link expiration timer for accessing each wireless power receiver.

In this case, the wireless power receiver must transmit a first predetermined message to inform the wireless power transmitter that it is in the charging area at a predetermined time period before the link expiration timer expires.

The link expiration timer can be reset each time a first message is received.

If the link expiration timer does not expire, the out-of-band communication link established between the wireless power transmitter and the wireless power receiver can be maintained.

However, when the link expiration timer expires, the out-of-band communication link established between the wireless power transmitter and the corresponding wireless power receiver may be disconnected.

If, in the low power state 730 or the power transmission state 740, if all link expiration timers corresponding to the out-of-band communication link established between the wireless power transmitter and the at least one wireless power receiver have expired, the state of the wireless power transmitter May transition to a power saving state 720.

In addition, the wireless power transmitter in the low power state 730 may drive a predetermined registration timer when a valid advertisement signal is received from the wireless power receiver.

At this time, when the registration timer expires, the wireless power transmitter in the low power state 730 may transition to the power saving state 720.

The wireless power transmitter may output a predetermined notification signal indicating that the registration has failed through the notification display means provided in the wireless power transmitter, including, for example, an LED lamp, a display screen, a beeper, and the like.

In addition, in the power transmission state 740, the wireless power transmitter may transition to the low power state 730 when charging of all connected wireless power receivers is completed.

In particular, the wireless power receiver may allow registration of a new wireless power receiver in a state other than the configuration state 710, local failure state 750, and lock failure state 760.

In addition, the wireless power transmitter may dynamically control the transmission power based on state information received from the wireless power receiver in the power transmission state 740.

At this time, the receiver status information transmitted from the wireless power receiver to the wireless power transmitter is for reporting required power information, voltage and/or current information measured at the rear end of the rectifier, charging status information, overcurrent and/or overvoltage and/or overheating status. The information may include at least one of information indicating whether a means for blocking or reducing power transmitted to a load is activated according to an overcurrent or an overvoltage. The receiver status information may be transmitted at a predetermined period or whenever a specific event occurs.

The wireless power receiver may be provided with an overpower blocking means such as a switch or a zener diode as a means for blocking or reducing power transmitted to a load when overcurrent or overvoltage is detected.

In another embodiment, the receiver status information transmitted from the wireless power receiver to the wireless power transmitter includes information indicating that the external power is connected to the wireless power receiver by wire, information indicating that the out-of-band communication method has been changed, for example, NFC (Near Field Communication) ) May be changed to Bluetooth Low Energy (BLE) communication.

As another embodiment, the wireless power transmitter may dynamically allocate transmission power for each wireless power receiver based on at least one of its currently available power, priority for each wireless power receiver, and the number of connected wireless power receivers.

Here, the power allocated to each wireless power receiver may be determined as a ratio of the maximum power that can be processed by the rectifier of the corresponding wireless power receiver to which power should be received.

Here, the priority of each wireless power receiver may be determined according to the strength of the power required by the receiver, the type of receiver, whether the receiver is currently used, the current charging amount, and the amount of power currently being consumed, but is not limited thereto.

For example, the priority of each receiver may be determined in the order of a mobile phone, a tablet, a Bluetooth headset, and an electric toothbrush, but is not limited thereto. As another example, when a receiver is currently being used, a higher priority may be given to a receiver that is not used.

As another example, the higher the power intensity required by the receiver, the higher priority may be given.

As another example, the priority may be determined based on the current charge amount of the load mounted on the receiver, that is, the remaining charge amount.

As another example, the priority may be determined based on the amount of power currently being consumed.

Also, it should be noted that the priority may be determined by a combination of at least one of the above-described priority determining elements.

Thereafter, the wireless power transmitter may transmit a predetermined power control command including information on the determined power strength to the corresponding wireless power receiver.

At this time, the wireless power receiver may determine whether power control is possible with the power strength determined by the wireless power transmitter, and transmit the determination result to the wireless power transmitter through a predetermined power control response message.

The wireless power receiver according to the embodiment may transmit predetermined receiver state information indicating whether power control according to the power control command of the wireless power transmitter is possible.

In another embodiment, before receiving the power control command, the wireless power receiver may transmit receiver state information indicating whether power control is possible to the wireless power transmitter.

The power transmission state 740 may be any one of the first state 741, the second state 742, and the third state 743 according to the power reception state of the connected wireless power receiver.

As an example, the first state 741 may mean that the power reception state of all wireless power receivers connected to the wireless power transmitter is a normal voltage.

The second state 742 may mean that the power reception state of at least one wireless power receiver connected to the wireless power transmitter is a low voltage state and a high voltage state wireless power receiver is not present.

The third state 743 may mean that the power reception state of at least one wireless power receiver connected to the wireless power transmitter is a high voltage state.

The wireless power transmitter may transition to the lock failure state 760 when a system error is detected in the power saving state 720 or the low power state 730 or the power transmission state 740.

When the wireless power transmitter determines that all wireless power receivers connected in the lock failure state 760 are removed from the charging area, the wireless power transmitter may transition to the configuration state 710 or the power saving state 720.

In addition, in the lock failure state 760, the wireless power transmitter may transition to the local failure state 750 upon detecting a local failure.

Here, the wireless power transmitter in the local failure state 750 may transition back to the lock failure state 760 when the local failure is released.

On the other hand, after the wireless power transmitter transitions from one of the configuration state 710, the power saving state 720, the low power state 730, or the power transmission state 740 to the local failure state 750, the local failure is released. If it does, it can transition to the configuration state 710.

When the wireless power transmitter transitions to the local failure state 750, the power supplied to the wireless power transmitter may be cut off.

For example, if the wireless power transmitter detects a failure such as overvoltage, overcurrent, or overheating, the wireless power transmitter may transition to the local failure state 750, but is not limited thereto.

In an embodiment, when the wireless power transmitter detects at least one of overcurrent, overvoltage, and overheating, the wireless power transmitter may transmit a predetermined power control command to reduce the intensity of power received at the wireless power receiver to the connected at least one wireless power receiver.

In another embodiment, when the wireless power transmitter detects at least one of overcurrent, overvoltage and overheating, the wireless power transmitter may transmit a predetermined control command to stop charging of the wireless power receiver to the connected at least one wireless power receiver.

Through the power control procedure as described above, the wireless power transmitter can prevent damage to the device due to overvoltage, overcurrent, and overheating.

When the intensity of the output current of the transmission resonator is greater than or equal to a reference value, the wireless power transmitter may transition to the lock failure state 760.

At this time, the wireless power transmitter transitioned to the lock failure state 760 may attempt to make the intensity of the output current of the transmission resonator less than a predetermined reference value for a predetermined time.

Here, the attempt may be repeatedly performed for a predetermined number of times.

If, despite repeated execution for a predetermined number of times, the lock failure state 760 is not released, the wireless power transmitter uses a predetermined notification means to instruct the user that the lock failure state 760 is not released. A predetermined notification signal can be transmitted.

At this time, if all wireless power receivers located in the charging area of the wireless power transmitter are removed from the charging area by the user, the lock failure state 760 may be released.

On the other hand, when the intensity of the output current of the transmission resonator falls below a reference value within a predetermined time or when the intensity of the output current of the transmission resonator falls below a reference value during the predetermined repetition, the lock failure state 760 is automatically released. Can.

At this time, the wireless power transmitter may automatically transition from the lock failure state 760 to the power saving state 720 to perform the detection and identification procedure for the wireless power receiver again.

The wireless power transmitter continuously transmits power in the power transmission state 740, and adaptively controls the intensity of the transmission power based on the state information of the wireless power receiver and a predefined optimal voltage region setting parameter. can do.

For example, the optimal voltage region setting parameter includes at least one of a parameter for identifying a low voltage region, a parameter for identifying an optimum voltage region, a parameter for identifying a high voltage region, and a parameter for identifying an overvoltage region. It can contain.

The wireless power transmitter may increase the strength of the transmission power when the power reception state of the wireless power receiver is in the low voltage region, and decrease the strength of the transmission power when it is in the high voltage region.

The wireless power transmitter may control the transmission power such that the deviation of the amount of power required by the wireless power receiver is below a reference value.

The wireless power transmitter may stop power transmission when the rectifier output voltage of the wireless power receiver reaches a predetermined overvoltage region, that is, when an over voltage is detected.

The wireless power transmitter may adaptively control resonance efficiency.

The wireless power transmitter may set a low initial resonance efficiency to prevent a wireless power receiver that is too close from being damaged by excessive received power.

In the power saving state 720, the initial resonance efficiency is set to the lowest, so that the wireless power receiver can be safely detected and charged regardless of the Z-distance, which is the separation distance between the wireless power transmitter and the wireless power receiver.

For example, the initial resonance efficiency may be set so low that there is no device damage even in a state where the wireless power transmitter and the wireless power receiver are closest to each other.

The wireless power transmitter according to the embodiment may dynamically control resonance efficiency such that V_RECT measured at the rear end of the rectifier of the wireless power receiver is maintained below a predetermined first reference.

In addition, the wireless power transmitter according to the embodiment may dynamically control the resonance efficiency such that V_RECT measured at the rear end of the rectifier of the wireless power receiver becomes a predetermined second reference or higher.

Here, the first criterion may be set larger than the second criterion.

The wireless power transmitter according to the embodiment may dynamically control resonance efficiency so that V_RECT measured at the rear end of the rectifier of the wireless power receiver maintains an appropriate voltage.

The wireless power transmitter according to the embodiment may control resonance efficiency by adjusting a capacitance value of the LC resonance circuit.

In the embodiment of FIG. 4, it is exemplified that the resonance efficiency is controlled by adjusting the capacitance value of the LC resonance circuit, but this is only one embodiment, and the wireless power transmitter according to another embodiment of the LC resonance circuit It is also possible to control the resonance efficiency by adjusting the value.

The wireless power transmitter according to another embodiment may control resonance efficiency by adjusting both a capacitance value and an inductance value of the LC resonance circuit.

8 is a view for explaining a resonance frequency and an operating frequency in an inductive wireless charging method.

In detail, FIG. 8 is a graph showing a change in gain according to frequency when the transmission power is 5 watts (W) in one of the inductive wireless charging scheme WPC.

Referring to FIG. 8, the operating frequency band in the WPC standard is 110 KHz to 205 KHz, which is a frequency band higher than 100 KHz, which is a resonance frequency.

It can be seen that the gain at the resonance frequency is about 35 dBV, but the gain in the operating frequency band is 15 dBV at the maximum.

The inductive wireless charging system is always assigned an operating frequency band to operate in a gain section lower than the resonant frequency.

To this end, the WPC forcibly miss-matches the reference clock, which is the resonant frequency and the operating frequency, determined by the inductance and capacitance of the resonant circuit, thereby lowering the strength of the AC voltage output through the resonant circuit.

On the other hand, the general resonant wireless charging method maintains the maximum Q value as a quality factor by fixing the operating frequency to the resonant frequency for remote wireless charging.

When the operating frequency is the resonance frequency, the gain is maximum, so the AC output voltage of the resonance circuit is the maximum.

Therefore, the resonant wireless charging method can overcome the power loss caused by the distance between the transceivers by compensating through a high frequency gain using the resonance frequency.

However, if the separation distance between the transceivers during charging is instantaneously reduced, the power loss may decrease rapidly, and a high voltage may be applied to the receiver, thereby causing fatal damage to the receiver.

In particular, when a high voltage is applied to the receiver according to a sudden movement of the receiver, there is a problem that it is difficult to quickly reduce the overvoltage to a normal voltage through a normal closed-loop power control algorithm.

9 is a view for explaining a minimum distance between the transceiver and the resonance frequency change according to the combination of capacitances of the resonance circuit of the embodiment.

9, it is assumed that the capacitance of the resonant circuit connected to the driving circuit of the transmitter is adjusted by the two capacitance variables CAP_A and CAP_B.

The inductance value of the resonant circuit according to the embodiment of FIG. 9 is 215 micro handles [uH].

In this embodiment, it is assumed that the maximum rectifier output voltage to prevent damage to the wireless power receiver is 90V.

Referring to drawing numbers 920 and 930, when CAP_A and CAP_B are 12.4 [uH] and 11.9 [uH], respectively, the separation distance between the transceivers at a rectifier output voltage of 90 V is 10 cm, and the resonance frequency at this time is 140.1 kHz.

That is, when CAP_A and CAP_B are 12.4 [uH] and 11.9 [uH], respectively, the minimum separation distance of the transceiver to prevent damage to the receiver is 10 cm.

When CAP_A and CAP_B are 10.4 [uH] and 11 [uH], respectively, the separation distance between the transceivers at the rectifier output voltage of 90 V is 7 cm, and the resonance frequency at this time is 149.7 kHz.

That is, when CAP_A and CAP_B are 10.4 [uH] and 11 [uH], respectively, the minimum separation distance of the transceiver to prevent damage to the receiver is 7 cm.

When CAP_A and CAP_B are 8.4 [uH] and 10 [uH], respectively, the separation distance between the transceivers at the rectifier output voltage of 90 V is 3 cm, and the resonance frequency at this time is 160 kHz.

That is, when CAP_A and CAP_B are 8.4 [uH] and 10 [uH], respectively, the minimum separation distance of the transceiver to prevent damage to the receiver is 3 cm.

When CAP_A and CAP_B are 6.4 [uH] and 8 [uH], respectively, the separation distance between the transceivers at the rectifier output voltage of 90 V is 1 cm, and the resonance frequency at this time is 180.7 kHz.

That is, when CAP_A and CAP_B are 6.4[uH] and 8[uH], respectively, the minimum separation distance between transmission and reception to prevent damage to the receiver is 1cm.

In the wireless power transmitter, when the separation distance between the transceivers decreases when the CAP_A and CAP_B are set to 12.4[uH] and 11.9[uH], respectively, and the rectifier output voltage exceeds the reference value of 90V, the rectifier is adjusted by adjusting the CAP_A and CAP_B to a small value. The output voltage can be lowered below 90V.

10 is a flowchart illustrating a method for transmitting wireless power in a resonant wireless power transmitter according to an embodiment.

Referring to FIG. 10, when the booting is completed, the wireless power transmitter may set the capacitance of the resonance circuit to have the lowest resonance efficiency (S1001 ).

When an object is detected, the wireless power transmitter may check whether a response signal is received from the wireless power receiver (S1003). Here, the response signal may be an advertisement signal, but is not limited thereto.

As a result of the confirmation, when the response signal is received, the wireless power transmitter may charge the wireless power receiver through closed-loop power control after establishing a communication connection with the wireless power receiver (S1007).

The wireless power transmitter may determine whether power required by the wireless power receiver cannot be provided through closed-loop power control (S1009).

When the wireless power transmitter receives a feedback signal including information on the rectifier output voltage, power is controlled by adjusting the duty or (and) phase of the PWM signal applied to the inverter based on the received feedback information. Can be done.

As a result of the determination, if it is impossible to provide the required power, the wireless power transmitter may reset the capacitance of the resonant circuit to have the next-level resonance efficiency (S1011).

Thereafter, it may return to step 1007 and perform closed-loop power control.

As a result of the check in step 1005, if a response signal is not received within a predefined time, the wireless power transmitter may reset the capacitance of the resonance circuit to have the next-level resonance efficiency (S1013).

Thereafter, the wireless power transmitter may check again whether a response signal is received from the wireless power receiver.

11 is a flowchart illustrating a method for transmitting wireless power in a resonant wireless power transmitter according to an embodiment.

Referring to FIG. 11, the wireless power transmitter may detect the presence of an object disposed in the charging area (S1001).

When an object is detected, the wireless power transmitter may set resonance efficiency to an initial value (S1003). Here, the initial value may be a value having the lowest resonance efficiency.

For example, the lowest resonance efficiency may be set by adjusting the capacitance value of the resonance circuit to the minimum value.

The wireless power transmitter may identify whether the detected object is a rechargeable receiver (S1005).

When the identification fails, the wireless power transmitter may check whether the currently set resonance efficiency is maximum (S1107).

As a result of the confirmation, if it is not the maximum, the wireless power transmitter may gradually increase the resonance efficiency until the receiver is normally identified (S1109).

As a result of the check in step 1107, when the resonance efficiency is maximum, the wireless power transmitter may output a predetermined warning alarm by using the provided alarm means, and then wait for a certain period of time while the power transmission is paused (S1111). .

Thereafter, the wireless power receiver may return to step 1101 described above.

For example, the alarm means may include a display, speaker, beeper, LED lamp, vibrator, etc., but is not limited thereto.

In step 1105, when the receiver is identified, the wireless power transmitter may receive information about the required power from the receiver (S1113).

The wireless power transmitter may determine whether the required power of the receiver can be supplied with the currently set resonance efficiency (S1115).

For example, the wireless power transmitter may determine whether it is possible to supply the required power of the receiver by performing closed-loop power control with the currently set resonance efficiency.

In detail, the wireless power transmitter may determine that resonant efficiency resetting is necessary if the required power of the receiver is not supplied even though the maximum power is adjusted through closed-loop power control for a predetermined time.

The wireless power transmitter may control the transmission power based on the feedback information of the receiver if it is possible to supply the required power of the receiver with the currently set resonance efficiency (S1117).

As a result of the determination in step 1115, if it is impossible to supply the required power of the receiver with the currently set resonance efficiency, the wireless power transmitter may reset the resonance efficiency in correspondence with the required power of the receiver (S1119). Thereafter, the wireless power transmitter may perform closed-loop power control with reset resonance efficiency.

12 is a flowchart illustrating a method for transmitting wireless power in a resonant wireless power transmitter according to another embodiment.

Referring to FIG. 12, the wireless power transmitter may receive a feedback signal including a rectifier output voltage V_RECT in a power transmission state (S1201).

The wireless power transmitter may compare V_RECT with the first criterion (S1203).

As a result of comparison, when V_RECT exceeds the first criterion, the wireless power transmitter may lower the resonance efficiency stepwise (S1205). Thereafter, the wireless power transmitter may return to step 1201 described above.

As a result of the comparison in step 1203, when V_RECT is less than or equal to the first reference, the wireless power transmitter may compare V_RECT with the second reference (S1207). Here, the second criterion may be set to a smaller value than the first criterion.

When V_RECT is less than the second criterion, the wireless power transmitter may increase resonance efficiency stepwise (S1209). Thereafter, the wireless power transmitter may return to step 1201 described above.

As a result of the comparison in step 1207, when V_RECT is greater than or equal to the second reference, the wireless power transmitter may perform power control based on V_RECT (S1211).

13 is a view for explaining a method of controlling wireless power of a wireless power transmitter according to an embodiment.

Referring to FIG. 13, the wireless power transmitter may stop power transmission when V_RECT, the rectifier output voltage of the receiver, exceeds a predetermined upper limit.

The wireless power transmitter may perform closed-loop power control when V_RECT is between a first reference and a second reference that are appropriate voltage intervals.

When the V_RECT is between the upper limit and the first reference, the wireless power transmitter may reduce the resonance efficiency step by step such that V_RECT enters an appropriate voltage section.

When the V_RECT is a value between the second reference and the lower limit, the wireless power transmitter may increase the resonance efficiency step by step such that V_RECT enters an appropriate voltage section.

Here, when V_RECT is lower than the lower limit, the communication connection between the transmitter and the receiver may be released, and feedback information may not be received any more.

When V_RECT is below the lower limit, the resonance efficiency may be initialized to the lowest value.

When an object is detected while the resonance efficiency is set to the lowest value, the wireless power transmitter may gradually increase the resonance efficiency until the wireless power receiver is identified.

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

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

Claims (18)

Sensing an object disposed in the charging area by setting the resonance efficiency to a minimum; And
When the object is detected, stepwise increasing the resonance efficiency until a response signal from the wireless power receiver is received.
Wireless power transmission method of a wireless power transmitter comprising a. According to claim 1,
The resonance efficiency is a wireless power transmission method of the wireless power transmitter is set by adjusting the capacitance of the resonance circuit provided in the wireless power transmitter. According to claim 1,
The resonance efficiency is set by adjusting the inductance of the resonance circuit provided in the wireless power transmitter. According to claim 1,
The resonance efficiency is set by adjusting the capacitance and inductance of the resonance circuit provided in the wireless power transmitter. According to claim 1,
When the response signal is received, connecting a communication to receive information on the required power from the wireless power receiver; And
Performing closed loop power control based on the required power
Including,
If the supply of the required power is not possible through the closed-loop power control, the wireless power transmission method of the wireless power transmitter to increase the resonance efficiency step by step until the required power can be supplied. The method of claim 5,
A method of transmitting wireless power of a wireless power transmitter, the method comprising: receiving information about V_RECT, a rectifier output voltage of a wireless power receiver, and gradually increasing the resonance efficiency when the V_RECT is below a second reference during the closed-loop power control. . The method of claim 6,
And when the V_RECT exceeds the first criterion during the closed-loop power control, gradually reducing the resonance efficiency, wherein the first criterion is a value greater than the second criterion. The method of claim 6,
And stopping the wireless power transmission when the V_RECT exceeds a predetermined upper limit during the closed-loop power control, wherein the upper limit is a value greater than the first criterion. According to claim 1,
If the response signal is not received until the resonance efficiency is maximized, the wireless power transmission method of the wireless power transmitter to stop the power transmission for a period of time after outputting a warning alarm. A transmitting coil that transmits wireless power;
A communication antenna for transmitting and receiving wireless signals;
A modem that processes signals transmitted and received through the communication antenna;
A resonance efficiency control circuit for setting resonance efficiency; And
Transmission controller for controlling the resonance efficiency control circuit
Including,
A wireless power transmitter in which the transmission controller detects an object disposed in a charging area by setting the resonance efficiency to a minimum, and gradually increases the resonance efficiency until a response signal is received from the wireless power receiver through the modem. The method of claim 10,
The resonance efficiency is a wireless power transmitter that is set by adjusting the capacitance of the resonance efficiency control circuit. The method of claim 10,
When the response signal is received, the transmission controller connects communication with the wireless power receiver to receive information on required power from the wireless power receiver, and performs wireless power control based on the requested power. The method of claim 12,
Further comprising an inverter for generating an AC power signal based on the driving voltage and the reference signal,
A wireless power transmitter in which the transmission controller adjusts the intensity of the wireless power by controlling the duty and/or phase of the reference signal during the closed-loop power control. The method of claim 12,
If the requested power cannot be supplied through the closed-loop power control, the wireless power transmitter for gradually increasing the resonance efficiency until the transmission controller can supply the requested power. The method of claim 14,
A wireless power transmitter for gradually increasing the resonance efficiency when the transmission controller receives information on V_RECT, which is a rectifier output voltage of the wireless power receiver, during the closed-loop power control, and the V_RECT is less than a second reference. The method of claim 15,
The transmission controller
When the V_RECT of the closed-loop power control exceeds a first criterion, which is a value greater than the second criterion, the wireless power transmitter for gradually reducing the resonance efficiency. The method of claim 16,
If the V_RECT of the closed loop power control exceeds a predetermined upper limit that is a value greater than the first reference, the transmission controller stops the transmission of the wireless power. The method of claim 10,
If the response signal is not received until the resonance efficiency is maximized, the wireless power transmitter for stopping the transmission of the wireless power for a predetermined time after outputting a warning alarm provided with the transmission controller.

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