WO2019231120A1

WO2019231120A1 - Method and device for wireless power transmission

Info

Publication number: WO2019231120A1
Application number: PCT/KR2019/005224
Authority: WO
Inventors: 이윤복; 손정남; 이준희
Original assignee: 엘지이노텍(주)
Priority date: 2018-05-29
Filing date: 2019-04-30
Publication date: 2019-12-05

Abstract

The present invention relates to a wireless power transmission method and a wireless power transmitter. A method for wireless power transmission by a wireless power transmitter according to an embodiment of the present invention may comprise: a first transmission step of transmitting a first sensing signal having a first operating frequency; a first measurement step of measuring an output current of a direct current-direct current converter; a first comparison step of comparing the measured output current with a predetermined threshold current; and a second transmission step of transmitting a second sensing signal having a second operating frequency when the measured output current is greater than the threshold current. Therefore, the present invention can effectively remove noise generated by a metallic object and the like disposed in a charging area.

Description

Wireless power transmission method and apparatus

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless power transfer technology, and more particularly, to a method and apparatus for wireless power transfer capable of removing noise generated by an object disposed in a charging region.

Recently, with the rapid development of information and communication technology, a ubiquitous society based on information and communication technology is being made.

In order for telecommunications devices to be connected anytime and anywhere, sensors incorporating computer chips with communication functions must be installed in all social facilities.

Therefore, the problem of power supply of these devices and sensors is a new problem. In addition, as the number of mobile devices such as Bluetooth handsets and music players such as iPods has increased rapidly, charging a battery has required users time and effort.

In recent years, wireless power transmission technology has been attracting attention as a way to solve this problem.

Wireless power transmission or wireless energy transfer is a technology that transmits electrical energy wirelessly from a transmitter to a receiver using the principle of induction of magnetic field, which is already used by electric motors or transformers using the electromagnetic induction principle in the 1800s. Since then, there have been attempts to transmit electrical energy by radiating electromagnetic waves such as high frequency, microwaves, and lasers. Electric toothbrushes and some wireless razors that we commonly use are actually charged with the principle of electromagnetic induction.

To date, energy transmission using wireless may be classified into magnetic induction, electromagnetic resonance, and RF transmission using short wavelength radio frequency.

The magnetic induction method uses the phenomenon that magnetic flux generated at this time causes electromotive force to other coils when two coils are adjacent to each other and current flows to one coil, and is rapidly commercialized in small devices such as mobile phones. Is going on.

Magnetic induction is capable of transmitting power of up to several hundred kilowatts (kW) and has high efficiency, but the maximum transmission distance is less than 1 centimeter (cm).

The magnetic resonance method is characterized by using an electric or magnetic field instead of using electromagnetic waves or current. Since the magnetic resonance method is hardly affected by the electromagnetic wave problem, it has the advantage of being safe for other electronic devices or the human body.

On the other hand, it can be utilized only in limited distances and spaces, and has a disadvantage in that energy transmission efficiency is rather low.

The short wavelength wireless power transmission scheme—simply, the RF transmission scheme— takes advantage of the fact that energy can be transmitted and received directly in the form of RadioWave.

This technology is a wireless power transmission method of the RF method using a rectenna, a compound word of an antenna and a rectifier (rectifier) refers to a device that converts RF power directly into direct current power.

In other words, the RF method is a technology that converts AC radio waves to DC and uses them. Recently, research on commercialization has been actively conducted as efficiency is improved.

Wireless power transfer technology can be used in various industries, such as the mobile, IT, railroad and consumer electronics industries.

Therefore, there is a need for a wireless power transmission apparatus that supplies various levels of wireless power.

Wireless charging is important to maximize charging efficiency, but it is also important to minimize user inconvenience.

In the conventional wireless power transmission apparatus, when a metallic object is disposed in a charging region, there is a problem that the metallic object vibrates to generate noise.

The present invention has been devised to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a wireless power transmission method and apparatus capable of removing noise generated by an object disposed in a charging region.

Another object of the present invention is to provide a wireless power transmitter that is not only cost competitive, but also compact and lightweight.

It is still another object of the present invention to provide a wireless power transmission method and apparatus capable of minimizing electromagnetic interference.

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

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

In a wireless power transmission method of a wireless power transmitter according to an embodiment, a first transmission step of transmitting a first sensing signal of first power through an antenna, a first measurement step of measuring an output current of a DC-DC converter, and the measured The first comparison step of comparing the output current and the predetermined threshold current and the measured output current is greater than the threshold current, controlling the duty rate of the pulse width modulated signal applied to the inverter to the second sense signal of the second power; A second transmission step of transmitting via an antenna, wherein the first power may be greater than the second power.

In another embodiment, a wireless power transmission method of a wireless power transmitter includes a first transmission step of transmitting a first sensing signal of first power through an antenna, a first measurement step of measuring an output current of a DC-DC converter, and the measurement. A first comparison step of comparing the output current with a predetermined threshold current and the measured output current greater than the threshold current, controlling a phase of a pulse width modulation signal applied to the inverter to generate a second sensing signal of the second power. A second transmission step of transmitting via an antenna, wherein the first power may be greater than the second power.

In another embodiment, a wireless power transmission method of a wireless power transmitter includes a first transmission step of transmitting a first sensing signal of first power through an antenna, a first measurement step of measuring an output current of a DC-DC converter, and A first comparing step of comparing the measured output current with a predetermined threshold current and the measured output current is greater than the threshold current, an operating frequency, a duty rate of a pulse width modulated signal applied to the inverter, and a phase of the pulse width modulated signal And transmitting a second sensing signal of a second power through the antenna by controlling at least two of the first power, wherein the first power is greater than the second power.

According to another embodiment, a wireless power transmitter includes an antenna for transmitting a first sensing signal having a first operating frequency, a DC-DC converter for converting first DC power applied from an external power source into a second DC power, and the DC A current sensor for measuring the output current of the direct current converter and the measured output current and a predetermined threshold current, and when the measured output current is greater than the threshold current, a second sensing signal having a second operating frequency causes the antenna to It may include a controller for controlling to be transmitted through.

Here, the first operating frequency may be greater than the second operating frequency.

The antenna may include an LC resonant circuit, and the first operating frequency may be a frequency closer to the resonant frequency of the LC resonant circuit than the second operating frequency.

In addition, the output voltage of the DC-DC power converter may be maintained at the same time when the first sensing signal and the second sensing signal are transmitted.

In addition, the first sensing signal and the second sensing signal may be digital pings.

In addition, the second operating frequency may be a value between 111 KHz and 115 KHz.

In addition, the threshold current may be a minimum current at which noise is generated by a metallic object disposed in a charging area of the wireless power transmitter.

The controller may control the first sensing signal having the first operating frequency to be transmitted when the output current of the DC-DC converter decreases by a predetermined reference value or more during the transmission of the second sensing signal.

In addition, when the output current of the DC-DC converter is greater than the threshold current during the transmission of the first sensing signal, the wireless power transmitter generates noise by a metallic object disposed in the charging area according to a control signal of the controller. It may further include an alarm unit for outputting a predetermined alarm indicating.

In another embodiment, a wireless power transmission method of a wireless power transmitter includes a first transmission step of entering a normal mode when an object is detected and transmitting a first detection signal corresponding to a first voltage, and a DC- during transmission of the first detection signal. A first determination step of measuring a first output current of the DC converter and a first determination step of comparing the first output current and the first threshold current to determine whether to enter a joint mode, and the first output current is the first determination step. If greater than one threshold current, entering a second mode and transmitting a second sensed signal corresponding to a second voltage, wherein the first threshold current is set differently according to a transmitter type; One voltage may be greater than the second voltage.

In addition, the operating frequency may be maintained to be the same when the first and second sensing signals are transmitted.

In addition, the allowable range of the first voltage is 3.3 ~ 3.6V, the allowable range of the second voltage may be 0.9 ~ 1.2V.

The first threshold current may be determined as a sum of a first reference current and a first offset current corresponding to the first voltage, and the first offset current may be determined according to the transmitter type.

According to an embodiment, the first offset current may be a constant value.

The first offset current according to the embodiment may be a variable value that increases or decreases in proportion to the first reference current.

In addition, the first reference current may be 400 mA.

The wireless power transmission method may further include a second measurement step of measuring a second output current of the DC-DC converter during the transmission of the second sensing signal, and comparing the second output current with a second threshold current to the normal mode. The method may further include a second determining step of determining whether to enter.

Here, the second threshold current may be determined as a sum of a second reference current and a second offset current corresponding to the second voltage, and the second offset current may be determined according to the transmitter type.

In addition, the second offset current may be smaller than the first offset current.

According to an embodiment, the second offset current may be a constant value.

According to an embodiment, the second offset current may be a variable value that increases or decreases in proportion to the second reference current.

In addition, the first threshold current and the second threshold current may be stored and maintained in a predetermined recording area of the corresponding wireless power transmitter.

According to another embodiment of the present invention, a wireless power transmitter generates an antenna for transmitting a sensing signal and a first sensing signal corresponding to a first voltage in a normal mode, and generates a second sensing signal corresponding to a second voltage in a joint mode. A current sensor measuring a first output current of a DC-DC converter provided in the power converter during the transmission of the power converter and the first sensing signal provided to the antenna, and comparing the first output current with a first threshold current And a controller configured to determine whether to enter a mode and to control the controller to enter the joint mode when the first output current is greater than the first threshold current, wherein the memory stores the first threshold current. Is different depending on the transmitter type, and the first voltage may be greater than the second voltage.

Here, the operating frequency may be maintained at the same time when the first sensing signal and the second sensing signal are transmitted.

In addition, the first reference current may be 400 mA.

In addition, the current sensor measures the second output current of the DC-DC converter during the transmission of the second sensing signal, and whether the controller enters the normal mode by comparing the second output current with a second threshold current. Can be determined.

In addition, the second threshold current may be stored and maintained in the memory.

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

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

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

The present invention has the advantage of providing a wireless power transmission method and apparatus capable of removing noise generated by an object disposed in a charging region.

In addition, the present invention has the advantage of providing a wireless power transmission method and apparatus capable of minimizing electromagnetic interference.

In addition, the present invention has the advantage that it is possible to provide a wireless power transmitter with a low manufacturing cost and a simple structure by using a fixed voltage DC-DC converter rather than a variable voltage system.

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

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

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

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

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

5 is a state transition diagram illustrating a wireless power transmission procedure according to another embodiment of the present invention.

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

6B is a diagram for describing a configuration of an antenna included in the wireless power transmitter of FIG. 6A according to an embodiment of the present invention.

7 is a view for explaining the operation of the inverter in an embodiment of the present invention.

8 is a view for explaining the form of a transmission coil according to an embodiment of the present invention.

FIG. 9A is an exemplary diagram for describing a change in current flowing through an LC resonant circuit according to a change in resonant frequency and operating frequency of the LC resonant circuit.

FIG. 9B is an exemplary diagram for describing a method of controlling noise generated by a metallic object disposed in a charging region in a ping step.

10 is a flowchart illustrating a noise canceling method in a wireless power transmitter according to an embodiment of the present invention.

11 is a flowchart illustrating a noise canceling method in a wireless power transmitter according to another embodiment of the present invention.

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

13 is a flowchart illustrating a noise canceling method in a wireless power transmitter according to another embodiment of the present invention.

14 is a flowchart illustrating a noise canceling method in a wireless power transmitter according to another embodiment of the present invention.

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

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

17 is a view for explaining the noise determination logic in the wireless power transmitter according to the present invention.

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

The wireless power transmission method of the wireless power transmitter according to an embodiment of the present invention includes a first transmission step of transmitting a first sensing signal having a first operating frequency and a first measurement step of measuring an output current of a DC-DC converter; A first comparing step of comparing the measured output current with a predetermined threshold current and a second transmitting step of transmitting a second sensing signal having a second operating frequency when the measured output current is greater than the threshold current. have.

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

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

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

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

The transmitter according to the present invention may be configured in a pad form, a cradle form, an access point (AP) form, a small base station form, a stand form, a ceiling buried form, a wall hanging form, and the like. You can also transfer power.

To this end, the transmitter may comprise at least one wireless power transmission means. Here, the wireless power transmission means may use a variety of radio power transmission standards based on the electromagnetic induction method to generate a magnetic field in the power transmitting coil and to charge using the electromagnetic induction principle in which electricity is induced in the receiving coil by the influence of the magnetic field.

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

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

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

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

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

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

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

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

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

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

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

For example, the state information of the electronic device 30 may include current power usage information, information for identifying a running application, CPU usage information, battery charge status information, battery output voltage / current information, and the like. The information may be obtained from the electronic device 30 and may be utilized for wireless power control.

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

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

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

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

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

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

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

Referring to FIG. 3, the apparatus 300 for transmitting power wirelessly may include a controller 310, a power converter 320, an antenna 330, and a demodulator 340.

The power converter 320 may convert DC power into AC power according to a control signal of the controller 310.

The antenna 330 may be connected to an output terminal of the power converter 320 and wirelessly output through a transmission coil (not shown) provided with an AC power signal generated by the power converter 320.

The antenna 330 may further include at least one of a short range wireless communication antenna for short range wireless communication such as near field communication (NFC) and a mobile payment antenna for wireless mobile payment service, as well as a transmission coil for wireless power transmission. It may be configured to include.

In this case, the transmitting coil, the wireless communication antenna and the mobile payment antenna may be arranged so as not to overlap each other to minimize mutual interference.

The demodulator 340 may be connected to one side of the antenna 330, and may include an analog digital converter.

The demodulator 340 may demodulate the signal received through the antenna 330 and then deliver the demodulated packet to the controller 310.

According to an embodiment of the present invention, the controller 310 and the demodulator 340 may be integrated into one module (or chipset) in hardware.

In another embodiment of the present invention, some functions and configurations of the demodulator 340 may be integrated into the controller 310.

The controller 310 may dynamically determine an operating point based on a predetermined packet received from the demodulator 340, which may be, for example, a control error packet containing a control error value. The controller 310 may control (or set) a predetermined power control parameter corresponding to the determined operating point, thereby adjusting the strength of the wireless power transmitted through the antenna 330.

For example, the controller 310 controls a power control parameter of at least one of an operating frequency, a duty rate of a pulse width modulated signal, and a phase of a pulse width modulated signal according to the determined operating point. To control the output of the power converter 320.

In an embodiment, the power converter 320 converts a DC voltage applied from an external power source into a predetermined DC voltage and outputs the DC-DC converter (not shown) based on a reference signal received from the controller 310. A gate driver (not shown) for generating a modulated signal and an inverter (not shown) for generating an AC power signal by controlling a switch provided according to a pulse width modulation signal received from the gate driver.

In another embodiment, the power converter 320 is a DC-DC converter (not shown) for converting a DC voltage applied from an external power source into a predetermined DC voltage and outputting the same, according to a plurality of pulse width modulation signals from the controller 310. It may be configured to include an inverter (not shown) for controlling the switch to generate an AC power signal.

The detailed configuration of the power converter 320 will be more apparent through the description of the drawings to be described later.

The inverter provided in the power converter 320 according to an embodiment of the present invention may be implemented as a half bridge inverter or a full bridge inverter.

As shown in FIG. 7 to be described later, the half bridge circuit 7a includes two switches, and the full bridge circuit 7b includes four switches.

Accordingly, the full bridge circuit may have a power amplification ratio of up to twice as much as that of the half bridge circuit, but may also be up to twice the power loss caused by the switch element.

The full bridge circuit can also be operated in half bridge mode, depending on how the drive signal, i.e., the pulse width modulated signal, is controlled, thereby providing a wide range of power.

Referring to FIG. 4, the power transmission from the transmitter to the receiver is largely selected in a selection phase 410, a ping phase 420, an identification and configuration phase 430, and a power transmission phase ( Power Transfer Phase 440).

The selection step 410 may be a step of transitioning when a specific error or a specific event is detected while starting or maintaining the power transmission.

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

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

If the transmitter detects that an object is placed on the interface surface, it may transition to the ping step 420 (S401).

In the selection step 410, the transmitter transmits a very short pulse of an analog ping signal, and may detect whether an object exists in an active area of the interface surface based on a change in current of a transmitting coil.

In the ping step 420, when an object is detected, the transmitter activates the receiver and transmits a digital ping to identify whether the receiver is a receiver that is compliant with the standard.

If the transmitter does not receive a response signal (for example, a signal strength indicator) from the receiver in response to the digital ping in step 420, it may transition back to the selection step 410 (S402).

In addition, in the ping step 420, when the transmitter receives a signal indicating that power transmission is completed, that is, a charging completion signal, from the receiver, the transmitter may transition to the selection step 410 (S403).

When the ping step 420 is completed, the transmitter may transition to the identification and configuration step 430 for collecting receiver identification and receiver configuration and status information (S404).

In the identification and configuration step 430, the transmitter either receives an unwanted packet (unexpectedpacket), the desired packet has not been received for a predefined time (time out), a packet transmission error (transmission error), or a power transmission contract If it is not set (no power transfer contract) it may transition to the selection step 410 (S405).

When the identification and configuration of the receiver is completed, the transmitter may transition to the power transmission step 240 for transmitting the wireless power (S406).

In power transfer step 440, the transmitter either receives an unwanted packet (unexpectedpacket), does not receive a desired packet for a predefined time, or violates a preset power transfer contract (power transfer). contract violation), if the filling is completed, the transition to the selection step (410) (S407).

In addition, in the power transmission step 440, if the transmitter needs to reconfigure the power transmission contract in accordance with the change in the transmitter state, it may transition to the identification and configuration step 430 (S408).

The power transmission contract may be set based on state and characteristic information of the transmitter and the receiver. For example, the transmitter state information may include information on the maximum transmittable power, information on the maximum acceptable number of receivers, and the like. The receiver state information may include information on required power.

Referring to FIG. 5, power transmission from a transmitter to a receiver is largely selected as a selection phase 510, a ping phase 520, an identification and configuration phase 530, and a negotiation phase. Phase 540, a calibration phase 550, a power transfer phase 560, and a renegotiation phase 570.

The selection step 510 may be a step of transitioning when a specific error or a specific event is detected while starting or maintaining power transmission.

Here, specific errors and specific events will be apparent from the following description. In addition, in the selection step 510, the transmitter may monitor whether an object exists on the interface surface.

If the transmitter detects that an object is placed on the interface surface, it may transition to ping step 520. In the selection step 510, the transmitter transmits a very short pulse of an analog ping signal and an object in the active area of the interface surface based on the current change of the transmitting coil or the primary coil. Can detect the presence of

In ping step 520, when an object is detected, the transmitter activates the receiver and sends a digital ping to identify whether the receiver is a receiver that is compliant with the WPC standard. If in ping step 520 the transmitter does not receive a response signal (eg, a signal strength packet) to the digital ping from the receiver, it may transition back to selection step 510.

Further, in ping step 520, the transmitter may transition to selection step 510 when it receives a signal from the receiver indicating that power transmission is complete, i.e., a charge complete packet.

Once the ping step 520 is complete, the transmitter may transition to identification and configuration step 530 to identify the receiver and collect receiver configuration and status information.

In the identification and configuration step 530, the transmitter either receives an unwanted packet (unexpectedpacket), the desired packet has not been received for a predefined time (time out), a packet transmission error (transmission error), or a power transmission contract If not set (no power transfer contract) it may transition to selection step 510.

The transmitter may determine whether entry into the negotiation step 540 is necessary based on a negotiation field value of the configuration packet received in the identification and configuration step 530.

As a result of the check, if negotiation is necessary, the transmitter may enter a negotiation step 540 and perform a predetermined FOD detection procedure.

On the other hand, if the result of the check is that negotiation is not necessary, the transmitter may directly enter the power transmission step 560.

In the negotiation step 540, the transmitter may receive a Foreign Object Detection (FOD) status packet including a reference quality factor value. In this case, the transmitter may determine a threshold for FO detection based on the reference quality factor value.

The transmitter may detect whether the FO exists in the charging region by using the determined threshold for FO detection and the currently measured quality factor value, and control power transmission according to the FO detection result. For example, when the FO is detected, power transmission may be stopped, but is not limited thereto.

If the FO is detected, the transmitter may return to selection step 510. On the other hand, when the FO is not detected, the transmitter may enter the power transmission step 560 via the correction step 550.

In detail, when the FO is not detected, the transmitter determines the strength of the power received at the receiving end in the correction step 550, and determines the power loss at the receiving end and the transmitting end to determine the strength of the power transmitted by the transmitting end. It can be measured.

That is, the transmitter may predict the power loss based on the difference between the transmit power of the transmitter and the receive power of the receiver in the correction step 550.

The transmitter according to an embodiment may correct the threshold for FOD detection by reflecting the predicted power loss.

In the power transmission step 540, the transmitter receives an unexpected packet, the desired packet has not been received for a predefined time, or a violation of a preset power transmission contract occurs. transfer contract violation), if the filling is complete, transition to selection step 510.

In addition, in power transmission step 440, the transmitter may transition to renegotiation step 570 if it is necessary to reconfigure the power transmission contract according to a change in the transmitter state.

At this time, if the renegotiation is normally completed, the transmitter may return to the power transmission step (560).

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

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

Referring to FIG. 6A, the apparatus for transmitting power wirelessly 600 may largely include a controller 610, a power converter 620, an antenna 630, a demodulator 640, and a current sensor 650.

Here, the power converter 623 may include a gate driver 622, an inverter 622, and a DC-DC converter 623.

The power converter 620 may be configured to be supplied to the inverter 622 after the first DC voltage V_in applied from the power source 660 is converted into the second DC voltage V_rail.

The gate driver 621 may generate the first to N th switch control signals SC_1 and SC_N using a reference clock signal (Ref_CLK) or an operating frequency signal received from the controller 610.

The inverter 622 may switch-control the second DC voltage V_rail according to the first to Nth switch control signals to generate an AC power signal.

The antenna 630 may wirelessly transmit an AC power signal received from the inverter 622.

In the present embodiment, the antenna 630 may include an LC resonant circuit including at least one inductor L and at least one capacitor C. According to an embodiment, the antenna 630 may be in the form of a single coil composed of one transmitting coil, that is, one inductor, but this is only one embodiment, and the antenna 630 according to another embodiment will be described later. As shown in 6b, it may consist of a plurality of transmitting coils, that is, a plurality of transmitting coils.

Hereinafter, the second DC power will be referred to as an inverter input voltage or a V rail or an inverter operating voltage.

The first to Nth switch control signals SC_1 and SC_N may be pulse width modulation signals, and an N value may be determined corresponding to the number of switches provided in the inverter 622.

The current sensor 650 measures the intensity of the current flowing through the output terminal of the DC-DC converter 623, that is, the inverter input current I_rail, according to the control signal of the controller 610, and measures the result of the controller 610. Can be delivered to.

As an example, the controller 610 enters a sensing signal—for example, a digital ping transmission—when the wireless power transmitter 600 enters a ping phase, and the current sensor 650 outputs a DC-DC converter 623 output current. Can be controlled to measure.

The controller 610 may compare the measured intensity I_rail with the predetermined threshold current I_threshold. Here, the threshold current may be a minimum current at which noise may be generated when a metallic object is disposed in the charging region of the corresponding wireless power transmitter 600 in the ping steps 420 and 520. Threshold current according to an embodiment may be determined based on the noise generation experiment results for the various metallic objects in the ping step (420, 520).

For example, the controller 610 may adjust the operating frequency according to the comparison result. If the resonant frequency of the LC resonant circuit included in the antenna 630 is a, the adjusted operating frequency may be determined to be greater than a. For example, when the resonant frequency of the LC resonant circuit included in the antenna 630 is 110KHz, the adjusted operating frequency may be determined as a value between 111KHz and 115KHz.

As another example, the controller 610 may adjust the duty rate of the pulse width modulated signal generated by the gate driver 621 according to the comparison result.

As another example, the controller 610 may adjust the phase of the plurality of pulse width modulated signals generated by the gate driver 621 according to the comparison result.

As another example, the controller 610 may adjust at least two of an operating frequency, a duty rate of the pulse width modulated signal, and a phase for the plurality of pulse width modulated signals according to the comparison result.

For example, the controller 610 may change the operating frequency such that the output current of the DC-DC converter 623 is decreased when the intensity of the output current measured in the ping step exceeds a predetermined threshold current.

As another example, the controller 610 may reduce the duty rate of the pulse width modulated signal such that the output current of the DC-DC converter 623 is decreased when the intensity of the output current measured in the ping step exceeds a predetermined threshold current. .

As another example, the controller 610 may adjust the phase difference between the plurality of pulse width modulated signals such that the output current of the DC-DC converter 623 is reduced when the intensity of the output current measured in the ping step exceeds a predetermined threshold current. You can also adjust.

As another example, the controller 610 may include the operating frequency, the duty rate of the pulse width modulated signal, and the output current of the DC-DC converter 623 when the intensity of the output current measured in the ping step exceeds a predetermined threshold current. At least two of the phases for the plurality of pulse width modulated signals may be combined and adjusted.

If the controller 610 according to an embodiment detects an additional output current decrease above a predetermined reference value after the output current of the DC-DC converter 620 decreases according to an operating frequency and / or duty rate and / or phase adjustment. It may be determined that the metallic object disposed in the charging region, that is, the object causing noise generation, has been removed.

When the controller 610 confirms that the metallic object has been removed, the controller 610 may restore at least one of the adjusted operating frequency, the duty rate, and the phase to a state before adjustment.

The wireless power transmitter 600 according to another embodiment of the present invention may further include an output unit (not shown) such as a lamp, a beeper, a liquid crystal display, and a vibrator.

According to an exemplary embodiment, the controller 610 may, when the intensity of the output current of the DC-DC converter 623 measured in the

ping step

420 or 520 exceeds a predetermined threshold current, transmit a metallic object to the charging region through the provided output unit. Is arranged to control the output of a predetermined warning alarm indicating that noise has occurred. In this case, the user may remove the metallic object disposed in the charging area according to the output warning alarm.

For example, when it is confirmed that the metallic object is removed from the charging region after the warning alarm output, the controller 610 may stop the warning alarm output and restore the adjusted operating frequency to the previous operating frequency.

According to an embodiment, the controller 610 compares the output current of the DC-DC converter 632 measured before and after the warning alarm output to determine whether the metallic object, that is, the object causing the noise, has been removed from the charging region. Can be determined. In detail, the controller 610 is a DC-DC after warning alarm output compared to the output current of the DC-DC converter 632 measured before the alarm alarm output after operating frequency and / or duty rate and / or phase adjustment. When the output current of the converter 632 decreases by more than a predetermined reference value, it may be determined that the metallic object is removed from the charging region.

As another example, when it is confirmed that the metallic object is removed from the charging region after the warning alarm output, the controller 610 may stop the warning alarm output and restore the adjusted duty rate to the duty rate before the adjustment.

As another example, when it is confirmed that the metallic object is removed from the charging region after the warning alarm output, the controller 610 may stop the warning alarm output and restore the adjusted phase to its original phase before adjustment.

As another example, when it is confirmed that the metallic object is removed from the charging region after the warning alarm output, the controller 610 stops the warning alarm output and sets at least one of the adjusted operating frequency, duty rate, and phase to a state before adjustment. You can also restore it.

Referring to FIG. 6B, the antenna 630 may include a coil selection circuit 631, a coil assembly 632, and a resonant capacitor 633.

The coil assembly 632 may comprise a plurality of transmitting coils, wherein the first through Nth coils, where N is two or more.

The coil selection circuit 631 includes first to N th switches configured to flow an output current I_coil of the inverter 620 to any one (or at least one) of the transmission coils included in the coil assembly 632. Can be configured.

As an example, the coil selection circuit 631 may be configured such that one end of the first N-th switch is connected to an output terminal of the inverter 620 and the other end of each switch is connected to a coil corresponding to the corresponding switch.

Each of the first to Nth coils included in the coil assembly 632 may be configured such that one end thereof is connected to one end of a corresponding switch of the coil selection circuit 710 and the other end thereof is connected to the resonant capacitor 633. Can be.

The demodulator 640 can demodulate and pass the signal between the coil assembly 632 and the resonant capacitor 633, where the signal can be an amplitude modulated in-band signal, to the controller 610.

7 is a view for explaining the operation of the inverter.

Referring to FIG. 7A, the half-bridge inverter includes two switches S1 and S2, and the corresponding switch may be controlled on / off according to the PWM signal of the gate driver so that the output voltage Vo may be changed. For example, as shown at 710, when the S1 switch is shorted and the S2 switch is open, the output voltage Vo has a value of + Vdc which is an input voltage. On the other hand, when the S1 switch is opened and the S2 switch is shorted, the output voltage Vo has a value of zero.

The half bridge inverter may receive first to second PWM signals having different phases from the gate driver, and control the S1 switch and the S2 switch using the first to second PWM signals. When the S1 switch and the S2 switch are cross-shorted according to the first to second PWM signals, the half bridge inverter may output an AC power signal having a specific period.

Referring to FIG. 7B of FIG. 7, the full bridge inverter may include four switches S1, S2, S3, and S4, and the switches may be turned on or off according to a PWM signal received from the gate driver. Can be controlled.

The output voltage Vo level of the full bridge inverter may have a value of + Vdc or -Vdc or 0, as shown at 720.

For example, when the S1 switch and the S2 switch are short-circuited and the remaining switches are open, the output voltage Vo level has a value of + Vdc. On the other hand, if the S3 switch and the S4 switch are short-circuited and the remaining switches are open, the output voltage Vo level has a value of -Vdc.

According to an embodiment, the characteristics of the transmission coils 800 provided in the above-described

transmission antennas

330 and 630 illustrated in FIGS. 3 and 6 may have its inner diameter d _i , inner diameter d _o , outer diameter) and thickness (d _c , thickness).

In addition, when the transmitting coil 800 according to an embodiment has a spiral wound shape, the characteristic of the transmitting coil 800 may be further determined based on the number of turns thereof.

The resonant frequency of the LC resonant circuit may be different according to the characteristics of the transmitting coil provided in the wireless power transmitter 600. In addition, the output current change pattern of the DC-DC converter 623 according to the change in the operating frequency according to the characteristics of the transmission coil may also be different.

The wireless power transmitter utilizes LC resonance to transmit energy. In the LC resonant circuit in which the inductor L and the capacitor C are connected in series, the frequency closer to the resonant frequency is used as the operating frequency, the impedance is lowered and the current flowing through the LC resonant circuit is maximum.

On the other hand, as the operating frequency moves away from the resonant frequency, the impedance increases, and the current flowing through the LC resonant circuit decreases.

In the present embodiment, it is assumed that the resonant frequency of the LC resonant circuit disposed in the wireless power transmitter is f ₀ , and the initial operating frequency is f ₁ .

That is, the wireless power transmitter may generate a digital ping using f _1, which is an initial operating frequency, in the ping step.

Referring to FIG. 9A, when the operating frequency is f ₀ , the current flowing through the LC resonant circuit may be I_max, which is the maximum value.

When the operating frequency is changed from f ₀ to f ₁ , the current flowing in the LC resonant circuit may be changed to I_f1 which is decreased by Δa from I_max.

If the operating frequency is changed from f ₁ to f ₂ , the current flowing in the LC resonant circuit may be changed to I_f 2, which is decreased by Δ b from I_f 1.

When the wireless power transmitter uses an operating frequency f ₁ and a foreign material, for example, a metallic object is placed in the charging region during the digital ping transmission, the current flowing through the LC resonant circuit increases rapidly and becomes larger than I_f1.

If the current flowing through the LC resonant circuit increases rapidly, a metallic object, an LC resonant circuit, or an adjacent electronic component may vibrate in the charging region to generate noise.

As an example, suppose that the output current (or current applied to the LC resonant circuit) of the DC-DC converter is measured at 1000 mA when there is no metallic object in the charging region during the ping step operating at the operating frequency f ₁ . In this case, when a metallic object is disposed in the charging region, the output current of the DC-DC converter may increase rapidly and be measured to be greater than or equal to a predetermined threshold current of 2000 mA.

If the output current of the DC-DC converter measured in the ping step exceeds the threshold current, the wireless power transmitter adjusts the operating frequency from f ₁ to f ₂ as shown in FIG. 9B to be described later. The output current can be controlled to fall below the threshold current. In this case, f ₂ may be higher than f ₁ .

FIG. 9B is an exemplary diagram for describing a method of controlling noise generated by a foreign material, for example, a metallic object in a ping step.

That is, suppose that the wireless power transmitter generates a digital ping using the operating frequency f ₁ in the ping step and then wirelessly transmits through the LC resonant circuit.

As shown in FIG. 9B, when the operating frequency is f ₀ , the current flowing in the LC resonant circuit may be I_max, which is the maximum value, as shown at 910.

If the operating frequency is f ₁ in the ping step and no object is disposed in the charging region, the current flowing in the LC resonant circuit may be I_f1 as shown in FIG.

However, when the metallic object is disposed in the charging region, the current flowing through the LC resonant circuit may be increased significantly more than the threshold current I_thre 950 as shown in reference numeral 930.

If the current flowing through the LC resonant circuit is greater than the threshold current I_thre 950, the metallic object may vibrate to generate noise.

The wireless power transmitter adjusts the operating frequency from f ₁ to f ₂ to control the current flowing in the LC resonant circuit to be smaller than the threshold current I_thre 950, as shown at 940.

When the current flowing through the LC resonant circuit is smaller than the threshold current I_thre 950, the vibration of the metallic object may be stopped to remove noise.

Referring to FIG. 10, the wireless power transmitter may enter a ping step and transmit a first sensing signal having a first operating frequency (S1010).

The wireless power transmitter may measure the output current of the DC-DC converter during the transmission of the first sensing signal (S1020).

The wireless power transmitter may compare whether the measured output current is greater than a predetermined threshold current (S1030).

As an example, the threshold current may be set to a minimum current at which noise is generated by the metallic object disposed in the charging region. Therefore, when the measured output current is greater than the threshold current, the wireless power transmitter may determine that the metallic object is disposed in the charging region.

As a result of the comparison, if the measured output current is greater than the threshold current, the wireless power transmitter may transmit a second sensing signal having a second operating frequency (S1040).

Here, the second operating frequency may be a frequency higher than the first operating frequency. For example, the first operating frequency may be 110 KHz and the second operating frequency may be 115 KHz. The second operating frequency is determined as a value capable of dropping the output current of the DC-DC converter measured greater than the threshold current among values greater than the first operating frequency to be smaller than the threshold current.

Table 1 below shows the experimental results of the measured output current according to the frequency.

번호number	주파수(KHz)Frequency (KHz)	전류(mA)Current (mA)
1One	111111	546546
22	112112	482482
33	113113	422422
44	114114	380380
55	115115	336336
66	116116	304304
77	117117	270270
88	118118	242242
99	119119	228228

Experimental results showed that the optimum frequency for reducing the output current to the threshold level (300 ~ 400mA) is 114KHz to 116KHz. The most suitable frequency may be 115 KHz. As a result of the comparison in step 1030, if the measured output current is less than the threshold current, the wireless power transmitter may return to step 1010.

Referring to FIG. 11, the wireless power transmitter may enter a ping step and transmit a first detection signal of first power (S1110).

The wireless power transmitter may measure the output current of the DC-DC converter during the transmission of the first sensing signal (S1120).

The wireless power transmitter may compare whether the measured output current is greater than a predetermined threshold current (S1130). As an example, the threshold current may be set to a minimum current at which noise is generated by the metallic object disposed in the charging region. Therefore, when the measured output current is greater than the threshold current, the wireless power transmitter may determine that the metallic object is disposed in the charging region.

As a result of the comparison, if the measured output current is greater than the threshold current, the wireless power transmitter may adjust the duty rate of the pulse width modulated signal applied to the inverter to transmit the second sensing signal of the second power (S1140).

Here, the second power may be smaller than the first power, and the duty rate of the pulse width modulated signal corresponding to the second sensing signal may be smaller than the duty rate of the pulse width modulated signal corresponding to the first sensing signal.

The duty rate of the pulse width modulated signal corresponding to the first sensed signal may be 0.5 (or 50%) and the duty rate of the pulse width modulated signal corresponding to the second sensed signal may be 0.3 (or 30%), which is one If only the duty rate of the pulse width modulated signal corresponding to the second sensing signal is determined as a value that can drop the output current of the DC-DC converter measured greater than the threshold current less than the threshold current Suffice.

As a result of the comparison in step 1130, if the measured output current is less than the threshold current, the wireless power transmitter may return to step 1110.

After the above step 1140, the wireless power transmitter may determine whether the metallic object disposed in the charging region is controlled during the transmission of the second sensing signal.

As a result of the determination, when the metallic object is removed, the wireless power transmitter may return to step 1110 to transmit the first detection signal of the first power.

On the other hand, if the metallic object is not removed as a result of the determination, the wireless power transmitter may control the second sensing signal transmission of the second power to be maintained.

The wireless power transmitter may be applied and mounted in various products, such as a vehicle. Thus, depending on the application to which the wireless power transmitter is applied, the operating frequency band used for wireless power transmission may act as an interference to a frequency band used for other applications of the product, for example, a radio frequency band.

The wireless power transmitter according to the embodiment of FIG. 11 has an advantage of effectively preventing the Electromagnetic Interference (EMI) problem by adjusting the duty rate of the pulse width modulated signal instead of changing the operating frequency.

Referring to FIG. 12, the wireless power transmitter may enter a ping step and transmit a first detection signal of first power (S1210).

The wireless power transmitter may measure the output current of the DC-DC converter during the first sensing signal transmission (S1220).

The wireless power transmitter may compare whether the measured output current is greater than a predetermined threshold current (S1230).

As a result of the comparison, if the measured output current is greater than the threshold current, the wireless power transmitter may control the phase of the pulse width modulation signal applied to the inverter to transmit the second sensing signal of the second power (S1240).

Here, the second power may be smaller than the first power, and the phase delay of the pulse width modulated signal corresponding to the second sensing signal may be greater than the phase delay of the pulse width modulated signal corresponding to the first sensing signal.

For example, the phase delay of the pulse width modulated signal corresponding to the first sensed signal is 30 degrees (or π / 6), and the phase delay of the pulse width modulated signal corresponding to the second sensed signal is 90 degrees (or π / 2). However, this is only an example, and the phase delay of the pulse width modulated signal corresponding to the second sensing signal may drop the output current of the DC-DC converter measured greater than the threshold current to be smaller than the threshold current. It is enough if it is determined by the value that can be reduced.

As a result of the comparison in step 1230, if the measured output current is less than the threshold current, the wireless power transmitter may return to step 1210.

After the above step 1240, the wireless power transmitter may determine whether the metallic object disposed in the charging region is controlled during the transmission of the second sensing signal.

As a result of the determination, when the metallic object is removed, the wireless power transmitter may return to step 1210 to transmit the first detection signal of the first power.

The wireless power transmitter according to the embodiment of FIG. 12 effectively prevents an Electromagnetic Interference (EMI) problem by adjusting a phase of a pulse width modulated signal applied to an inverter instead of changing an operating frequency to remove noise caused by a metallic object. There is an advantage to this.

Referring to FIG. 13, the wireless power transmitter may enter a ping step and transmit a first detection signal of first power (S1310).

The wireless power transmitter may measure the output current of the DC-DC converter during the transmission of the first sensing signal (S1320).

The wireless power transmitter may compare whether the measured output current is greater than a predetermined threshold current (S1330).

As a result of the comparison, if the measured output current is greater than the threshold current, the wireless power transmitter determines at least two of the operating frequency, the duty rate of the pulse width modulated signal, and the phase of the pulse width modulated signal so that the second sense signal of the second power is transmitted. Can be adjusted (S1340).

Here, the second power is smaller than the first power, and the wireless power transmitter may determine at least two of an operating frequency, a duty rate, and a phase based on an operating point determined corresponding to the second power.

As a result of the comparison in step 1330, if the measured output current is less than the threshold current, the wireless power transmitter may return to step 1310.

After the above step 1340, the wireless power transmitter may determine whether the metallic object disposed in the charging region is controlled during the transmission of the second sensing signal.

The wireless power transmitter according to the embodiment of FIG. 11 has an advantage of effectively preventing an electromagnetic interference (EMI) problem that may occur when controlling noise by changing only an operating frequency.

Referring to FIG. 14, the wireless power transmitter may enter a ping step and transmit a first sensing signal having a first operating frequency (S1410).

The wireless power transmitter may measure the output current of the DC-DC converter during the transmission of the first sensing signal (S1420).

The wireless power transmitter may compare whether the measured output current is greater than a predetermined threshold current (S1430).

As a result of the comparison, if the measured output current is greater than the threshold current, the wireless power transmitter may transmit a second sensing signal having a second operating frequency (S1440).

Here, the second operating frequency may be a frequency higher than the first operating frequency.

As an example, the first operating frequency may be 110 KHz and the second operating frequency may be 115 KHz. However, this is only an example, and the second operating frequency is greater than the threshold current among values greater than the first operating frequency. It is sufficient if it is determined to be a value that can drop the output current of the DC-DC converter below the threshold current.

As a result of the comparison of step 1430, if the measured output current is less than the threshold current, the wireless power transmitter may return to step 1410.

The wireless power transmitter may determine whether the metallic object disposed in the charging region is controlled during the transmission of the second sensing signal (S1450).

As a result of the determination, when the metallic object is removed, the wireless power transmitter may return to step 1410 to transmit the first detection signal having the first operating frequency.

As a result of the determination in step 1450, when the metallic object is not removed, the wireless power transmitter may return to step 1440.

The wireless power transmitter according to an embodiment of the present invention may determine whether the metallic object is controlled based on the change of the output current of the DC-DC converter during the transmission of the second sensing signal.

For example, after the transmission of the second sensing signal, a predetermined alarm message (or signal) indicating that noise is generated by the metallic object may be output through the output unit.

When the metallic object disposed in the charging area is removed from the charging area by the user according to the alarm message (or signal) output, the output current of the DC-DC converter may suddenly decrease during the transmission of the second sensing signal.

The wireless power transmitter may determine that the metallic object disposed in the charging region is removed from the charging region when the reduction level of the DC-DC converter output current during the second sensing signal transmission exceeds a predetermined reference value.

In the wireless power transmitter according to an exemplary embodiment of the present invention, a DC-DC converter supporting a variable voltage type may not be applied.

That is, according to an embodiment of the present invention, the DC-DC converter mounted on the wireless power transmitter may be configured to convert a DC voltage applied from an external power source into a DC voltage of a fixed specific level.

In general, the variable voltage DC-DC converter has a higher unit cost and a bulky disadvantage than the fixed voltage DC-DC converter.

Referring to FIG. 15, the wireless power transmitter 1500 may include a controller 1510, a power converter 1520, an antenna 1530, a demodulator 1540, a current sensor 1550, a memory 1560, and a power input terminal ( 1570).

The power converter 1520 may include an inverter 1521 and a DC-DC converter 1523.

The first DC voltage V_in applied through the power input terminal 1570 may be converted into the second DC voltage V_rail by the DC-DC converter 1523 and then supplied to the inverter 1521.

The controller 1510 may generate and supply the first to Nth switch control signals SC_1 and SC_N to the inverter 1521 to control the plurality of switches included in the inverter 1521.

The inverter 1521 may switch control the second DC voltage V_rail according to the first to Nth switch control signals to generate an AC power signal.

The first to N th switch control signals may be pulse width modulation signals.

The antenna 1530 may be wirelessly output using a resonant circuit (not shown) having an AC power signal received from the inverter 1521.

The antenna 1530 may include an LC resonant circuit including at least one inductor (L) and at least one capacitor (C).

The antenna 1530 may be in the form of a single coil composed of one transmitting coil, that is, one inductor, but this is only one embodiment, and the antenna 1530 according to another embodiment is illustrated in FIG. 6B. As noted, it may be configured to include a plurality of transmit coils, that is, a plurality of transmit coils.

The second DC power output of the DC-DC converter 1523 may be used interchangeably with the inverter input voltage or V_rail or the inverter operating voltage for convenience of description.

The N values of the first to Nth switch control signals SC_1 and SC_N may be equal to the number of switches provided in the inverter 621, for example, MOSFET switches.

The current sensor 650 measures the intensity of the current flowing through the output terminal of the DC-DC converter 1523, that is, the inverter input current I_rail, according to the control signal of the controller 1510, and measures the measurement result of the controller 1510. Can be delivered to.

For example, the output current of the DC-DC converter 1520 may be an output current corresponding to the sensing signal. Here, the sensing signal may be a digital ping.

The controller 1510 controls the current sensor 1550 to measure the output current of the DC-DC converter 1523 when the wireless power transmitter 1500 enters a ping phase and initiates a detection signal—eg, a digital ping transmission. can do.

The controller 1510 may control the power converter 1520 such that the first sensing signal corresponding to the first voltage is transmitted in the ping step of the normal mode.

The controller 1510 may control the power converter 1520 such that a second sensing signal corresponding to the second voltage is transmitted in the pinging step of the joint mode.

For convenience of description, the current measured by the current sensor 1550 during the transmission of the first sensing signal corresponding to the first voltage in the normal mode is referred to as a first output current, and the first voltage corresponding to the second voltage in the joint mode is referred to as a first output current. 2 The current measured by the current sensor 1550 during the detection signal transmission will be referred to as a second output current.

The controller 1510 may determine whether the first output current and the first threshold current enter the joint mode.

When the first output current is greater than the first threshold current, the controller 1510 may enter the joint mode and control the second sensing signal corresponding to the second voltage to be transmitted.

According to an embodiment, the first threshold current may be a fixed value. However, when the first threshold current is a fixed value, there may be a problem of entering the silent mode even when the situation is not entered into the silent mode. Even in the transmitter of the same design, a process error occurs in the inductance of the coil and the capacitance of the capacitor, because the actual first threshold current has a large dispersion.

According to another embodiment, the first threshold current may have a different value according to the type of the transmitter, and may be stored and maintained in the memory 1560. For example, the first threshold current may be set to different values according to individual transmitter types. Therefore, since the first threshold current can be set by reflecting the process error of the inductance and the capacitor capacity of the coil of each transmitter, there is an effect that can solve the malfunction problem of the joint mode.

In addition, the first voltage may be greater than the second voltage.

For example, the first voltage is 3.5V, the second voltage may be 1.0V, but is not limited thereto. In another example, the allowable range of the first voltage is 3.3V to 3.6V and the allowable range of the second voltage. May be 0.9 to 1.2V.

The controller 1510 may control the operating frequency to remain the same when transmitting the first and second sensing signals.

The first threshold current may be determined by the sum of the first reference current and the first offset current corresponding to the first voltage, and the first offset current may be a predefined value in consideration of the tolerance of the corresponding transmitter type and the resonant circuit.

The inductance of the transmitting coil and the capacitance of the resonant capacitor constituting the resonant circuit may be different within a certain tolerance depending on the product.

As an example, the tolerance may be 10%. In addition to the tolerances of the resonant circuit, the output current may be measured differently for each transmitter even with the same driving voltage input according to the transmitter configuration.

For example, the first reference current may be a rail current I_rail measured when an object is placed in the charging region of the reference wireless power transmitter.

The first reference current may be 400 mA, but is not limited thereto. The rail current measured when the object is placed in the charging region of the wireless power transmitter having a different performance and shape than the reference wireless power transmitter may be different from the first reference current.

The first threshold current according to the embodiment is determined based on the first reference current measured during transmission of the first sensing signal of the first voltage in the reference wireless power transmitter and the first offset current determined differently by the transmitter type. It is possible to detect the placed joint generating object more accurately.

The current sensor 1550 may measure the intensity of the output current of the DC-DC converter 1523 during the transmission of the second sensing signal according to the control signal of the controller 1510, and transmit the measurement result to the controller 1510.

Hereinafter, the output current measured during the transmission of the second sensing signal, that is, the output current measured after the entry into the joint mode, will be referred to as the second output current in order to clearly distinguish the first output current measured in the normal mode. do.

The controller 1510 may determine whether to re-enter the normal mode by comparing the second output current with the second threshold current stored in the memory 1560.

As an example, when the joint generating object disposed in the charging region is removed by the user, the DC-DC converter 1523 output current may decrease below the second threshold current.

As another example, the controller 1510 may determine whether to re-enter the normal mode by comparing the second output current with the second threshold current range stored in the memory 1560. At this time, when the joint generating object disposed in the charging region is removed by the user, the DC-DC converter 1523 output current may be reduced to within the second threshold current range. For example, the second threshold current range may be set greater than -50 mA and less than 200 mA.

The controller 1510 may switch from the joint mode to the normal mode to transmit the first detection signal corresponding to the first voltage, and then identify the receiver to control normal charging.

The first sensing signal may be a digital ping having sufficient power for the controller provided in the wireless power receiver to wake up.

The second threshold current may be determined as the sum of the second reference current and the second offset current corresponding to the second voltage. The second offset current may be a value determined differently according to the transmitter type. The second offset current may be predetermined based on a pretest result for each transmitter type and a tolerance of the resonant circuit.

The second offset current may be determined to be smaller than the first offset current.

When the wireless power transmitter 1500 according to an embodiment is mounted in a vehicle, at least one of the first offset current and the second offset current may be determined in consideration of background noise of the vehicle in which the transmitter is mounted.

The wireless power transmitter 1500 according to an exemplary embodiment of the present invention may further include an output means (not shown) such as a lamp, a beeper, a liquid crystal display, and a vibrator.

If the first output current measured in the normal mode exceeds the first threshold current, the controller 1510 may generate a predetermined warning alarm indicating that a metallic object is placed in the charging region to generate noise. Can be. The generated warning alarm may be output through the provided output means.

The user can remove the metallic object placed in the charging area according to the output warning alarm.

According to an embodiment of the present disclosure, the controller 1510 may enter the coupling mode after outputting the warning alarm and control the second sensing signal of the second voltage to be transmitted.

The controller 1510 may re-enter the normal mode when it is determined that the metallic object has been removed from the charging region when the measured second output voltage falls below the second threshold voltage after entering the joint mode.

After reentering the normal mode, the controller 1510 may stop the warning alarm output and control the first sensing signal of the first voltage to be transmitted.

In one embodiment, if the controller 1510 determines that the noise generating object is not removed from the charging area even after a predetermined time has passed after entering the noise mode, the controller 1510 outputs a warning level, for example, the volume and vibration of the alarm sound. And may include, but is not limited to, alarm intensity, and the like.

In the above embodiment, the information about the first threshold current and the second threshold current for determining the entry into the joint mode and the re-entry into the normal mode is based on the test result of the corresponding wireless power transmitter before shipment from the memory 1560. It is described that the controller 1510 performs the joint determination logic with reference to the first to second threshold currents stored in the memory 1560 during operation.

In another embodiment, the output current corresponding to each of the first voltage and the second voltage is measured for each of the first situation where the metallic object is disposed in the charging region of the wireless power transmitter and the second situation where the metallic object is not disposed in the charging region. In addition, the information about the measured output current may be stored and maintained in the memory 1560 before leaving the factory.

In this case, when an object is detected after entering the selection step, the controller 1510 may transmit a detection signal of a second voltage, for example, 1.1 V, to determine whether the object disposed in the charging region is a metallic object that generates a noise. Can be.

For example, the controller 1510 may be configured to output currents a and c corresponding to the second voltages of the first and second situations maintained in the memory 1560 and the output current a measured during the transmission of the sensing signal of the second voltage. Comparing the threshold currents b and c determined based on this, it is possible to determine whether to enter the joint mode.

The threshold currents b and c can be determined by applying a certain tolerance to the output currents b and c.

If the output current a is greater than the threshold current b, the controller 1510 may determine that the object disposed in the charging region is a splice generating object.

On the other hand, if the output current a is less than the threshold current c, the controller 1510 may determine that the object disposed in the charging region is not a splice generating object.

As a result of the determination, if the object disposed in the charging region is not the noise generating object, the controller 1510 may enter the normal mode and control the transmission of the detection signal of the first voltage.

If, as a result of the determination, the object disposed in the charging region is a noise generating object, the controller 1510 may maintain the second voltage and enter the noise mode to control a predetermined warning alarm to be output.

After the warning alarm output or during the warning alarm output, when it is confirmed that the noise generating object disposed in the charging region is removed, the controller 1510 may enter the normal mode and control the transmission of the detection signal of the first voltage.

Referring to FIG. 16, the wireless power transmitter may detect an object disposed in the charging region (S1601).

When the object is detected, the wireless power transmitter may enter a normal mode and transmit a first sensing signal corresponding to the first voltage (S1603).

The wireless power transmitter may measure the first output current of the DC-DC converter provided during the first sensing signal transmission (S1605). For example, the wireless power transmitter may measure the first output current at a predetermined period for a unit time.

The wireless power transmitter may determine whether the first output current enters the joint mode by comparing the first threshold current (S1607).

In detail, when the first output current is greater than the first threshold current, the wireless power transmitter may determine that the noise generating object is disposed in the charging region and enter the noise mode.

On the other hand, if the first output current is less than or equal to the first threshold current, the wireless power transmitter may determine that no joint generating object exists in the charging region.

Here, the first threshold current is calculated as the sum of the first reference current and the first offset current corresponding to the first voltage, and the first offset current may be a value defined differently according to the transmitter type.

For example, the first reference current may be a rail current I_rail measured when an object is placed in the charging region of the reference wireless power transmitter, that is, the output current of the DC-DC converter 1523 of FIG. 15. The measurement position of the current may be determined differently according to the design of a person skilled in the art.

Here, the first reference current may be 400 mA, but is not limited thereto and may have a different value according to the type and configuration of the applied reference wireless power transmitter.

The rail current measured when the object is placed in the charging region of the wireless power transmitter having a different performance and shape than the reference wireless power transmitter may be different from the first reference current.

Therefore, since the first threshold current according to the embodiment is determined based on the first reference current measured during transmission of the first sensing signal of the first voltage on the reference wireless power transmitter and the first offset current differently determined by the transmitter type, the charging is performed. There is an advantage that it is possible to more accurately detect the joint generating object disposed in the area.

As a result of the comparison in step 707, when the first output current is greater than the first threshold current, the wireless power transmitter may enter the coupling mode and transmit a second sensing signal corresponding to the second voltage (S709). Here, the second voltage may be smaller than the first voltage.

When the wireless power transmitter according to the embodiment enters the joint mode, the inverter operating voltage may be lowered to reduce the rail current. Accordingly, the current flowing to the metallic object disposed in the charging region is reduced, so that noise generation can be stopped.

The wireless power transmitter may measure the second output current of the DC-DC converter during the transmission of the second sensing signal (S1611).

In operation S1613, the wireless power transmitter may compare the second output current with the second threshold current to determine whether the noise generating object is removed from the charging region.

In an embodiment, the second threshold current may be determined as the sum of the second reference current and the second offset current corresponding to the second voltage.

Here, the second offset current may be a value determined differently according to the transmitter type.

For example, the second offset current may be calculated in advance based on a pre-test result for each transmitter type. For example, the transmitter type may be defined in consideration of the type of the resonant circuit provided in the transmitter, the type of the vehicle in which the transmitter is mounted, and the like.

According to an embodiment, the second offset current may be determined to be smaller than the first offset current.

When the wireless power transmitter according to an embodiment is mounted in a vehicle, at least one of the first offset current and the second offset current may be determined in consideration of background noise of the vehicle in which the transmitter is mounted.

The wireless power transmitter according to the embodiment may generate the first sensing signal and the second sensing signal using the same operating frequency.

As a result of the comparison in step 1613, if the second output current is less than the second threshold current, the wireless power transmitter may reenter the normal mode and transmit a first sensing signal corresponding to the first voltage (S1615).

Subsequently, the wireless power receiver may identify the wireless power receiver disposed in the charging area and perform charging (S1617).

As a result of the comparison of step 1607, if the first output current is less than or equal to the first threshold current, the wireless power transmitter may perform step 1617.

The wireless power transmitter according to an exemplary embodiment of the present invention may further include an output means (not shown) such as a lamp, a beeper, a liquid crystal display, a vibrator, and the like.

The wireless power transmitter may control to output a predetermined warning alarm indicating that a metallic object generating noise is disposed in the charging area when the first output current measured in the normal mode exceeds the first threshold current. At this time, the warning alarm is output through the output means provided, the user can remove the metallic object disposed in the charging area according to the output warning alarm.

Referring to FIG. 17, when power is applied, the wireless power transmitter may transmit an analog ping of the first voltage.

When the object is detected during the analog ping transmission, the wireless power transmitter may enter a normal mode and transmit a digital ping of the first voltage.

If the object disposed in the charging region is a metallic object instead of the wireless power receiver, the output current I_rail may exceed the first threshold current.

In a normal mode, when a metallic object other than a wireless power receiver is disposed in a charging area during a digital ping transmission, an overcurrent may flow to the metallic object and generate noise.

In the normal mode, when the output current exceeds the first threshold current, the wireless power transmitter may determine whether to enter the joint mode.

As an example, when the output current measured for a predetermined first time is maintained larger than the first threshold current, the wireless power transmitter may determine that a joint generating object is disposed in the charging region. That is, the wireless power transmitter may switch from the normal mode to the joint mode.

When the wireless power transmitter switches to the joint mode, the driving voltage may be converted from the first voltage to the second voltage. Here, the second voltage may be a voltage lower than the first voltage.

For example, the first voltage may be 3.5V and the second voltage may be 1.0V, but the present invention is not limited thereto, and the first voltage may be a voltage at which the controller of the wireless power receiver, that is, the microprocessor, may be activated. The second voltage is sufficient as long as the generation of noise by the metallic object can be stopped.

When the wireless power transmitter enters the silent mode, a digital ping transmission corresponding to the second voltage causes the output current to be lower than the first threshold current, so that noise generation may be stopped.

When the noise generating object disposed in the charging region is removed during the digital ping transmission corresponding to the second voltage in the noise mode, the output current may be lower than the second threshold current.

When the output current is lower than the second threshold current in the joint mode, the wireless power transmitter may determine whether to re-enter the normal mode.

For example, in the joint mode, when the output current is maintained below the second threshold current for a predetermined second time, the wireless power transmitter may determine that the joint generating object is removed from the charging region.

If the wireless power transmitter determines that the noise generating object has been removed from the charging region, the wireless power transmitter may re-enter the normal mode and initiate a digital ping transmission corresponding to the first voltage.

The wireless power transmitter according to the embodiment may output a predetermined warning alarm indicating that the noise generating object is arranged in the charging area through the output means provided in the noise mode.

The wireless power transmitter may stop the alarm output and re-enter the normal mode by confirming that the noise generating object has been removed from the charging area after entering the noise mode.

Referring to FIG. 18, the wireless power transmitter may detect an object disposed in the charging region (S1801).

When the object is detected, the wireless power transmitter may transmit a detection signal corresponding to the second voltage (S1803). Here, the second voltage may be a voltage at which noise is not detected by the user even when a metallic object is disposed in the charging region. For example, the second voltage may be 1.1V, but is not limited thereto.

The wireless power transmitter may start measuring the output current of the DC-DC converter provided during the sensing signal transmission (S1805). As an example, the wireless power transmitter may measure the output current of the DC-DC converter at regular intervals.

The wireless power transmitter may determine whether the output current enters the joint mode by comparing the first threshold current corresponding to the second voltage in the first situation (S1807).

Here, the first situation may mean a state in which a joint generating object is disposed in the charging region of the corresponding wireless power transmitter. In detail, the wireless power transmitter may determine that a joint generating object is disposed in the charging region if the output current corresponds to the first threshold current, where the first threshold current may be a specific value or a specific range.

If the wireless power transmitter determines that the noise generating object is disposed in the charging region, the wireless power transmitter may maintain the second voltage, enter the noise mode, and start outputting a predetermined warning alarm (S1809).

The wireless power transmitter may determine whether to enter the normal mode by comparing the output current with a second threshold current corresponding to the second voltage of the second situation, where the second threshold current may be a specific value or a specific range. It may be (S1813). In this case, the second situation may mean a state in which a noise generating object is not disposed in the charging region of the corresponding wireless power transmitter.

As a result of the determination, when the output current corresponds to the second threshold current corresponding to the second voltage of the second situation, the wireless power transmitter may enter a normal mode and transmit a sensing signal corresponding to the first voltage (S1815). Here, the first voltage may be greater than the second voltage and may be a voltage capable of identifying the wireless power receiver disposed in the charging region. For example, the first voltage may be 3.5V, but is not limited thereto.

When the wireless power receiver is identified through the sensing signal corresponding to the first voltage, the wireless power transmitter may perform charging by transmitting wireless power to the identified wireless power receiver (S1817).

As a result of the determination in step 1813, if the output current does not correspond to the second threshold current corresponding to the second voltage of the second situation, that is, it is determined that the noise generating object disposed in the charging region is not removed, the wireless power The transmitter may raise the output level of the warning alarm (S1819).

As a result of the determination in step 1807, if the output current does not correspond to the first threshold current corresponding to the second voltage of the first situation, that is, if it is determined that no object is generated in the charging region, the wireless power transmitter determines that Step 1815 may be performed.

The first threshold current and the second threshold current according to the embodiment of FIG. 18 may be stored and stored before leaving the factory in a memory provided in the wireless power transmitter.

In addition, since the first threshold current and the second threshold current according to the embodiment of FIG. 18 are values determined based on an actual output current test result for the corresponding transmitter, the transmitter type and the mass deviation may be reflected.

Through this, the wireless power transmitter according to the embodiment has an advantage of more accurately detecting the noise generating object disposed in the charging region.

In addition, the wireless power transmitter according to the embodiment transmits a low voltage detection signal that does not generate noise even when a metallic object is placed in the charging region, and compares the DC-DC converter output current at that time with a predetermined threshold current stored in advance. Since it determines whether to enter the joint mode and the normal mode, there is an advantage that can prevent the occurrence of the joint in advance.

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

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

The present invention can be applied to a wireless power transmitter for wirelessly transmitting power to a wireless power receiver.

Claims

A first transmitting step of transmitting a first sensing signal having a first operating frequency;

A first measuring step of measuring an output current of the DC-DC converter;

A first comparing step of comparing the measured output current with a threshold current; And

A second transmission step of transmitting a second sensing signal having a second operating frequency when the measured output current is greater than the threshold current

Wireless power transmission method of a wireless power transmitter comprising a.
The method of claim 1,

And wherein the first operating frequency is greater than the second operating frequency and is close to a resonant frequency of the wireless power transmitter.
The method of claim 1,

The first sense signal and the second sense signal are digital pings,

And transmitting the first sensed signal and the second sensed signal to maintain the same output voltage of the DC-DC power converter.
The method of claim 1,

Wherein the threshold current is a minimum current at which noise is generated by a metallic object disposed in a charging region of the wireless power transmitter.
The method of claim 1,

Outputting a predetermined alarm indicating that noise is generated by a metallic object disposed in a charging region when the output current measured in the first measuring step is greater than the threshold current; And

A second measurement step of measuring a change in output current of the DC-DC converter during the transmission of the second detection signal;

Further comprising, and when the output current of the DC-DC converter measured in the second measuring step is reduced by a predetermined reference value or more, it is determined that the metallic object has been removed from the charging area and performs the first transmission step. Wireless power transmission method of power transmitter.
A first transmission step of transmitting a first sensed signal of first power through an antenna;

A first measuring step of measuring an output current of the DC-DC converter;

A first comparing step of comparing the measured output current with a threshold current; And

If the measured output current is greater than the threshold current, at least two of an operating frequency, a duty rate of a pulse width modulated signal applied to the inverter, and a phase of the pulse width modulated signal may be controlled to generate a second sensing signal of second power. A second transmission step transmitting through the antenna

And wherein the first power is greater than the second power.
An antenna for transmitting a first sensing signal having a first operating frequency;

A DC-DC converter converting the first DC power applied from the external power source into the second DC power;

A current sensor measuring an output current of the DC-DC converter; And

A controller for controlling a second sensing signal having a second operating frequency to be transmitted through the antenna when the measured output current is greater than the threshold current as a result of comparing the measured output current with a predetermined threshold current

Wireless power transmitter comprising a.
The method of claim 7, wherein

The antenna comprises an LC resonant circuit,

And the first operating frequency is greater than the second operating frequency and is closer to the resonant frequency of the LC resonant circuit than the second operating frequency.
The method of claim 7, wherein

The first sense signal and the second sense signal are digital pings,

And the controller controls the output voltage of the DC-DC power converter to remain the same when the first sensing signal and the second sensing signal are transmitted.
The method of claim 7, wherein

If the output current of the DC-DC converter is greater than the threshold current during the transmission of the first sensing signal, a predetermined alarm indicating that a noise is generated by a metallic object disposed in a charging region according to a control signal of the controller is output. It further includes an alarm unit to say,

The threshold current is a minimum current at which noise is generated by a metallic object disposed in a charging region of the wireless power transmitter,

And the controller controls the first sensing signal having the first operating frequency to be transmitted when the output current of the DC-DC converter decreases by a predetermined reference value or more during the transmission of the second sensing signal.