WO2013172530A1

WO2013172530A1 - Wireless charging apparatus, wireless charging system, and wireless charging method

Info

Publication number: WO2013172530A1
Application number: PCT/KR2012/011865
Authority: WO
Inventors: Min Seok Han; Young Sun Kim; Un Kyu Park; Ji Hyung Lee
Original assignee: Ls Cable Ltd.
Priority date: 2012-05-16
Filing date: 2012-12-31
Publication date: 2013-11-21
Also published as: KR101899161B1; KR20130128041A

Abstract

A wireless charging apparatus, a wireless charging system, and a wireless charging method are provided. The wireless charging apparatus for charging a rechargeable device includes an antenna for collecting an alternating magnetic field to receive power, a matching circuit for changing a resonant frequency of the antenna, and a controller for matching the resonant frequency of the antenna with a resonant frequency of the alternating magnetic field using the matching circuit. The controller determines whether or not the rechargeable device is adjacent to the wireless charging apparatus and transfers power to the rechargeable device using the antenna upon determining that the rechargeable device is adjacent to the wireless charging apparatus.

Description

WIRELESS CHARGING APPARATUS, WIRELESS CHARGING SYSTEM, AND WIRELESS CHARGING METHOD

The present invention relates to a wireless charging apparatus, a wireless charging system, and a wireless charging method using the same.

Recently, interest in energy-IT convergence technology is on the rise. Energy-IT convergence technology is technology for integrating IT technology, which is rapidly developing, with conventional energy technology. One field of such energy-IT convergence is a Wireless Power Transfer (WPT) technology. WPT is technology for supplying power to a household appliance or to an electric car wirelessly rather than using a conventional power line. Wireless power transfer technologies have been developed rapidly because these have an advantage in that it is possible to charge a household appliance or the like without connecting a power cable between an outlet and the household appliance or a rechargeable device.

Wireless power transmission technology which has been commercialized or developed may be mainly classified into 4 schemes. One is electromagnetic radiation transfer scheme. While it is useful for transmitting power to relatively long distance by using several GHz frequency band, it is generally not suitable for transferring power wirelessly due to problems such as a straightness property of microwaves and harmfulness of microwaves to human bodies. Another is a radiative type near-field transfer scheme. This is an RFID based scheme using an RFID/USN Ultra High Frequency (UHF) band or a 2.4GHz ISM band. The RFID based scheme has been commercialized in some fields such as distribution and logistics and has a problem in that it is possible to transmit power of only up to tens of mW due to radiative loss. On the other hand, a magnetic inductive scheme uses inductive coupling for transmitting power and transmits power of several W to a place at a distance of several mm to several cm. The magnetic inductive scheme uses a frequency such as 125kHz or 135kHz and is currently being applied to traffic cards, wireless shavers, electric toothbrushes, or the like. On the other hand, a magnetic resonance scheme is based on resonant coupling. Resonant coupling is a phenomenon in which an electromagnetic wave travels from one medium to another medium through a local magnetic field when the two media resonate at the same frequency. This scheme has an advantage in that it is possible to transmit great power of tens of W over a distance of several meters. However, to actually realize this scheme, there is a need to maintain a Quality Factor (Q-value) highly.

Alternating magnetic fields of various frequencies are generated through operation of various electronic devices. Such alternating magnetic fields persistently radiate and waste magnetic energy. Alternating magnetic fields may be collected using the inductive coupling transfer scheme and other electric devices may be charged using the collected magnetic energy.

Accordingly, when alternating magnetic fields are used, it is possible to charge various rechargeable devices using alternating magnetic fields even when an outlet or a power adapter is not available.

In this regard, Korean patent application publication No. 2011-0131954 describes an invention titled “wireless power transfer device and method”.

Specifically, the invention of Korean patent application publication No. 2011-0131954 describes a wireless power transfer device that detects a non-target receiver that does not allow reception of wireless power and prevents transfer of wireless power to the detected non-target receiver.

Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a wireless charging apparatus which can charge a load device using energy of alternating magnetic fields within a limited area.

It is another object of the present invention to provide a wireless charging apparatus which can charge various portable devices even when an external power source is not available.

The present invention is not limited to the above objects and other objects not described above will be clearly understood from the following description.

In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a wireless charging apparatus for charging a rechargeable device, the wireless charging apparatus comprising an antenna for collecting an alternating magnetic field to receive power, a matching circuit for changing a resonant frequency of the antenna, and a controller for matching the resonant frequency of the antenna with a resonant frequency of the alternating magnetic field using the matching circuit,

wherein the controller determines whether or not the rechargeable device is adjacent to the wireless charging apparatus and transfers power to the rechargeable device using the antenna upon determining that the rechargeable device is adjacent to the wireless charging apparatus.

The wireless charging apparatus may further comprising a communication unit for performing communication with the adjacent rechargeable device.

The communication unit may transmits a search signal at intervals of a first time, the communication unit determines whether or not a response signal corresponding to the search signal has been received from the rechargeable device within a second time after transmission of the search signal and then retransmits, upon determining that the response signal has not been received from the rechargeable device within the second time after transmission of the search signal, a search signal at intervals of the first time after a third time elapses, and the communication unit notifies the controller of reception of the response signal upon determining that the response signal has been received from the rechargeable device within the second time after transmission of the search signal.

The wireless charging apparatus may further comprising a second antenna having a different resonant frequency from the antenna.

The wireless charging apparatus may further comprising a second matching circuit for controlling the resonant frequency of the second antenna.

The controller may match the resonant frequency of the second antenna with a resonant frequency of the rechargeable device using the second matching circuit.

And in accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a wireless charging system comprising a rechargeable device including a rechargeable battery, and a wireless charging apparatus for collecting an alternating magnetic field to receive power and transferring the power as an RF signal to the rechargeable device, the wireless charging apparatus including an antenna for collecting an alternating magnetic field and transmitting the RF signal, a matching circuit for changing a resonant frequency of the antenna, and

a controller for matching the resonant frequency of the antenna with a resonant frequency of the alternating magnetic field using the matching circuit, the rechargeable device further including a device antenna for receiving the RF signal transmitted from the antenna, an impedance matcher for changing impedance of the device antenna to change a resonant frequency of the device antenna, and a charging unit for supplying power produced through conversion of the RF signal to the rechargeable battery, wherein the controller determines whether or not the rechargeable device is adjacent to the wireless charging apparatus and transfers power to the rechargeable device using the antenna upon determining that the rechargeable device is adjacent to the wireless charging apparatus.

The wireless charging apparatus may further include an apparatus communication unit for performing communication with the adjacent rechargeable device, wherein the rechargeable device further includes a device communication unit for communicating with the apparatus communication unit.

The apparatus communication unit may transmit a search signal at intervals of a first time, the apparatus communication unit determines whether or not a response signal corresponding to the search signal has been received from the device communication unit within a second time after transmission of the search signal and then retransmits, upon determining that the response signal has not been received from the device communication unit within the second time after transmission of the search signal, a search signal at intervals of the first time after a third time elapses, and the apparatus communication unit notifies the controller of reception of the response signal upon determining that the response signal has been received from the device communication unit within the second time after transmission of the search signal.

The wireless charging apparatus may further include a second antenna having a different resonant frequency from the antenna, and wherein the rechargeable device further includes a second device antenna corresponding to the second antenna.

The wireless charging system may further comprising a second matching circuit for controlling the resonant frequency of the second antenna.

And in accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a wireless charging method using an alternating magnetic field, the wireless charging method comprising measuring power received from an alternating magnetic field collected through an antenna and determining a position at which a wireless charging apparatus is to be arranged, searching for a rechargeable device that is adjacent to the wireless charging apparatus arranged at the determined position, detecting a resonant frequency of the alternating magnetic field using a matching circuit, changing a resonant frequency of the antenna so as to match with the detected resonant frequency, and transferring the power received from the alternating magnetic field to the rechargeable device.

Detecting the resonant frequency of the alternating magnetic field may include changing the resonant frequency of the antenna using the matching circuit and searching for a frequency at which the power received from the alternating magnetic field is maximized.

Searching for the rechargeable device may further include transmitting a search signal from a communication unit at intervals of a first time, awaiting reception of a response signal corresponding to the search signal from the rechargeable device during a second time after transmission of the search signal from the communication unit, retransmitting, when the reception signal has not been received within the second time, the search signal at intervals of the first time after a third time elapses, and transmitting, by a controller, power to the rechargeable device which has transmitted the response signal using the antenna when the response signal has been received within the second time.

The wireless charging method may further comprising detecting a resonant frequency of the rechargeable device using a second matching circuit, and

matching a resonant frequency of the second antenna with the resonant frequency of the rechargeable device, wherein the wireless charging apparatus transmits power to the rechargeable device or communicates with the rechargeable device using the second antenna.

And in accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a wireless charging method using an alternating magnetic field, the wireless charging method comprising detecting, by a communication unit, a rechargeable device when the rechargeable device is arranged adjacent to a wireless charging apparatus, measuring power received from an alternating magnetic field collected through an antenna and determining positions at which the wireless charging apparatus and the rechargeable device are to be arranged, detecting a resonant frequency of the alternating magnetic field using a matching circuit, changing a resonant frequency of the antenna so as to match with the detected resonant frequency, and transferring the power received from the alternating magnetic field to the rechargeable device.

Detecting the rechargeable device may further include transmitting a search signal from the communication unit at intervals of a first time, awaiting reception of a response signal corresponding to the search signal from the rechargeable device during a second time after transmission of the search signal from the communication unit, retransmitting, when the reception signal has not been received within the second time, the search signal at intervals of the first time after a third time elapses, and transmitting, by a controller, power to the rechargeable device which has transmitted the response signal using the antenna when the response signal has been received within the second time.

The wireless charging method may further comprising detecting a resonant frequency of the rechargeable device using a second matching circuit after detecting the rechargeable device, and matching a resonant frequency of the second antenna with the resonant frequency of the rechargeable device, wherein the wireless charging apparatus transmits power to the rechargeable device or communicates with the rechargeable device using the second antenna.

According to one embodiment of the present invention, it is possible to charge a load device using energy of alternating magnetic fields.

Also, according to one embodiment of the present invention, it is possible to charge various portable devices even when an external power source is not available.

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a general wireless power transfer device;

FIG. 2 is a schematic diagram illustrating a wireless charging apparatus and a rechargeable device included in a wireless charging system according to an embodiment of the present invention;

FIG. 3 illustrates a detailed configuration of a wireless charging system according to an embodiment of the present invention;

FIG. 4 illustrates a detailed configuration of a wireless charging apparatus according to an embodiment of the present invention;

FIG. 5 illustrates an exemplary communication method between a wireless charging apparatus and a rechargeable device in a wireless charging system according to an embodiment of the present invention;

FIG. 6 illustrates a detailed configuration of a wireless charging apparatus according to another embodiment of the present invention;

FIG. 7 is a flowchart illustrating a wireless charging method according to an embodiment of the present invention;

FIG. 8 is a flowchart illustrating a wireless charging method according to another embodiment of the present invention; and

FIG. 9 illustrates a wireless charging method according to another embodiment of the present invention.

The present invention may be modified in various ways and provide various embodiments. The present invention will be described below through a detailed description of specific embodiments illustrated in the accompanying drawings. The detailed description is not intended to limit the present invention and it should be understood that the present invention includes all changes, equivalents, or substitutions within the spirit and scope of the present invention.

In the following description of the present disclosure, a detailed description of known related technologies will be omitted when it may obscure the subject matter of the present disclosure. Numbers or ordinal numbers (for example, first and second) that are used in the description of this specification are merely reference symbols for discriminating between components.

When it is stated that one component is “connected” or “coupled” to another component, it is to be understood that the two components may not only be directly “connected” or “coupled” but may also be indirectly “connected” or “coupled” via another component unless specifically stated otherwise.

The term “rechargeable device” in this specification refers to a mobile device equipped with a rechargeable battery, which may include a mobile phone, a smartphone, a laptop, a digital broadcast terminal, a Personal Digital Assistants (PDA), a Portable Multimedia Player (PMP), or a navigation device.

A detailed description of embodiments for practicing the present invention will now be given with reference to the accompanying drawings.

FIG. 1 illustrates a general wireless power transfer device.

As shown in FIG. 1, in the wireless power transfer device, power is transferred between a wireless power transmission device (hereinafter referred to as a power transmitter) 10 and a wireless power reception device (hereinafter referred to as a power receiver) 20 through a magnetic inductive scheme or a magnetic resonance scheme.

The power transmitter 10 converts AC power received from an external power source 12 into an electromagnetic wave signal through internal circuits such as a rectifier (not shown) and a power amplifier (not shown) and transmits the electromagnetic wave signal to the power receiver 20 through a transmit antenna 11.

The power receiver 20 receives an electromagnetic wave signal transmitted from the power transmitter 10. To accomplish this, the power receiver 20 may include a receive antenna 21.

When the magnetic resonance scheme is used, the resonant frequency of the transmit antenna 11 and the receive antenna 21 may be equal or similar. In this case, resonant coupling creates an energy transmission channel between the transmit antenna 11 and the receive antenna 21. An electromagnetic wave emitted from the transmit antenna 11 is transmitted to the receive antenna 21 through an energy transmission channel and the electromagnetic wave input to the power receiver 20 through the receive antenna 21 is converted into power through internal circuits in the power receiver 20 such as an impedance matching circuit (not shown) and a rectifier (not shown). The converted power is transferred to a load device 30 connected to the power receiver 20 to charge the load device 30 or to supply drive power to the power receiver 20.

When the magnetic inductive scheme is used, it is possible to improve the efficiency of power transfer between the power transmitter 10 and the power receiver 20 by matching the resonant frequency of the transmit antenna 11 and the receive antenna 21 such that the resonant frequency of the transmit antenna 11 and the receive antenna 21 are nearly equal although the resonant frequency of the transmit antenna 11 and the receive antenna 21 do not need to be nearly equal.

A wireless charging system according to an embodiment of the present invention is described below with reference to FIG. 2 based on the wireless power transfer method described above.

FIG. 2 is a schematic diagram illustrating a wireless charging apparatus and a rechargeable device (or a to-be-charged device) included in a wireless charging system according to an embodiment of the present invention.

As shown in FIG. 2, the wireless charging system according to an embodiment of the present invention includes a wireless charging apparatus 100 and a rechargeable device 200 that is charged with power received through the wireless charging apparatus 100.

The wireless charging apparatus 100 may collect alternating magnetic fields in the air without being connected to any external power source and may then convert the collected alternating magnetic fields into power. The converted power may be transferred to the external rechargeable device 200 through a transmit antenna provided in the wireless charging apparatus 100 and may be used to charge a battery provided in the wireless charging apparatus 100.

The wireless charging apparatus 100 may include a display unit for displaying the magnitude of an alternating magnetic field detected at the current position. The wireless charging apparatus 100 may further include a speaker for audibly presenting the magnitude of the detected alternating magnetic field.

The wireless charging apparatus 100 may transfer power to the rechargeable device 200 using an RF signal through a transmit antenna. Here, the wireless charging apparatus 100 may use a magnetic resonance scheme or a magnetic inductive scheme as a power transfer scheme.

In the following, a method for transferring power between the wireless charging apparatus 100 and the rechargeable device 200 is described below in conjunction with a description of detailed components of the wireless charging system.

FIG. 3 illustrates a detailed configuration of a wireless charging system according to an embodiment of the present invention. A wireless charging apparatus 100 includes a transmit antenna 110, a matching circuit 120, and a controller 130. The wireless charging apparatus 100 may further include a communication unit 140 for performing communication with a rechargeable device 200. The rechargeable device 200 includes a receive antenna 210, an impedance matcher 220, a charging unit 230, and a battery 240 and may further include a communication unit 250 for performing communication with the communication unit 140 of the wireless charging apparatus 100. A communication method between the communication unit 140 of the wireless charging apparatus 100 and the battery 240 of the rechargeable device 200 will be described later with reference to FIG. 5.

The transmit antenna 110 collects an alternating magnetic field at the current position. The transmit antenna 110 may transfer power to the receive antenna 210 according to a control signal. Here, the transmit antenna 110 may transfer power to the receive antenna 210 in the form of an RF energy signal. In addition, it is preferable that the transmit antenna 110 and the receive antenna 210 which will be described later have the same or similar resonant frequencies.

The configuration of the wireless charging apparatus 100 may vary according to the wireless power transfer scheme. For example, when the wireless charging apparatus 100 is implemented according to the magnetic inductive scheme, the transmit antenna 110 may consist of a single loop antenna. On the other hand, when the wireless charging apparatus 100 is implemented according to the magnetic resonance scheme, the transmit antenna 110 may consist of a pair of a power transmission coil and a resonant coil for power transmission.

The transmit antenna 110 may be implemented in a loop form. Here, the transmit antenna 110 may be in a spiral loop form or a helical loop form.

The matching circuit 120 changes the resonant frequency of the transmit antenna 110. Specifically, the matching circuit 120 may be located at a rear side of the transmit antenna 110 to perform impedance matching between the transmit antenna 110 and the controller 130. The matching circuit 120 may include a variable capacitor or may include a parallel array structure in which circuits, including a capacitor and an FET switch which are connected in series, are connected in parallel. In addition, the variable capacitor or the parallel array structure may be connected to the transmit antenna 110 in series or in parallel to allow the resonant frequency of the transmit antenna 110 to be changed by changing the capacitance of the matching circuit 120.

The controller 130 matches the resonant frequency of the transmit antenna 110 with the resonant frequency of the alternating magnetic field using the matching circuit 120. In addition, as shown in FIG. 4, the controller 130 converts power received wirelessly through the transmit antenna 110 into a DC signal through a rectifier 132 and converts the DC signal into a desired voltage through a voltage amplifier 134.

The controller 130 may further include a frequency controller 136. The frequency controller 136 measures the amount of received power while changing the resonant frequency by controlling the capacitance of the matching circuit 120 and detects a frequency at which the maximum amount of power is acquired at the same position. The frequency controller 136 may perform a control operation to fix the resonant frequency to the frequency at which the maximum amount of power is acquired such that the maximum energy is received from the alternating magnetic field.

The power converted through the controller 130 may be stored in a battery 150 or may be again converted into required DC power and may then be transferred to the external rechargeable device 200. Specifically, the controller 130 may detect presence or absence of a rechargeable device 200 adjacent to the wireless charging apparatus 100 and may perform a control operation to transfer power to the detected rechargeable device 200 upon detecting presence of the rechargeable device 200.

Here, the controller 130 may detect presence or absence of a rechargeable device 200 adjacent to the wireless charging apparatus 100 through the communication unit 140 or by measuring a change in transfer current.

Specifically, when an external rechargeable device 200 is located adjacent to the wireless charging apparatus 100 while the wireless charging apparatus 100 is emitting energy through the transmit antenna 110, energy is transferred wirelessly from the transmit antenna 110 to the receive antenna 210 according to load of the rechargeable device 200 and current consumption of the wireless charging apparatus 100 increases accordingly. Here, the controller 130 may detect presence of the rechargeable device 200 at the adjacent position by measuring a rapid change in the current consumption of the wireless charging apparatus 100.

The controller 130 may also detect whether or not the rechargeable device 200 is present adjacent to the wireless charging apparatus 100 through communication with the rechargeable device 200. This will be described later in detail with reference to FIG. 5.

The rechargeable device 200 includes a receive antenna 210 and an impedance matcher 220. The receive antenna 210 may receive power from the transmit antenna 110 of the wireless charging apparatus 100 and the impedance matcher 220 may match the resonant frequency of the receive antenna 210 with the resonant frequency of the transmit antenna 110.

In addition, the rechargeable device 200 may further include a charging unit 230 for charging the battery 240 using the received power and a communication unit 250 for transmitting and receiving a message to and from the communication unit 140 of the wireless charging apparatus 100.

Next, a method for determining whether or not a rechargeable device is located adjacent to a wireless charging apparatus using communication between the rechargeable device and the wireless charging apparatus is described below with reference to FIG. 5.

FIG. 5 illustrates an exemplary method for performing communication between a wireless charging apparatus and a rechargeable device in a wireless charging system according to an embodiment of the present invention.

As shown in FIG. 5, the communication unit 140 of the wireless charging apparatus 100 and the communication unit 250 of the rechargeable device 200 may transmit a message to each other through magnetic field communication or load modulation communication using the transmit antenna 110 and the receive antenna 210. Alternatively, the wireless charging apparatus 100 and the rechargeable device 200 may further include

additional communication antennas

160 and 260 for communication between the wireless charging apparatus 100 and the rechargeable device 200.

The communication unit 140 of the wireless charging apparatus 100 sends an ACK signal (a search signal) to the communication unit 250 of the rechargeable device 200 at intervals of a predefined time period (hereinafter referred to as a first time) (S102). Here, the communication unit 140 may also transmit a search signal including power which is able to activate the communication unit 250 of the rechargeable device 200.

Thereafter, when the communication unit 140 of the wireless charging apparatus 100 has received a response signal in response to the search signal from the communication unit 250 of the rechargeable device 200 within a predefined time interval (hereinafter referred to as a second time), the communication unit 140 of the wireless charging apparatus 100 notifies the controller 130 of reception of the response signal (S104) and the controller 130 then starts wireless power transfer to the rechargeable device 200 which has transmitted the response signal. Here, the communication unit 140 may transmit an additional power transfer start signal to the communication unit 250 of the rechargeable device 200. In addition, the communication unit 140 may be configured to transmit a search signal at regular intervals during a power transfer procedure after power transfer starts (S106) and to receive a response signal in response to the search signal (S108).

In this manner, the wireless charging apparatus 100 may monitor the state of the rechargeable device 200. If the wireless charging apparatus 100 does not receive a response signal within the second time in response to the search signal transmitted in step S110, the wireless charging apparatus 100 may determine that the rechargeable device 200 is separated from the wireless charging apparatus 100 through a predetermined check procedure and may stop wireless power transfer to the rechargeable device 200 (S112). Thereafter, the communication unit 140 of the wireless charging apparatus 100 may retransmit a search signal at intervals of the first time after a predefined time (hereinafter referred to as a third time) elapses (S114).

In another embodiment of the present invention, the wireless charging apparatus 100 may further include an additional transmit antenna for communication and power transfer between the wireless charging apparatus 100 and the rechargeable device 200.

As shown in FIG. 6, the wireless charging apparatus 100 may include a second transmit antenna 160 in addition to the transmit antenna 110. The wireless charging apparatus 100 may further include a second matching circuit 170 for performing impedance matching of the second transmit antenna 160.

The second transmit antenna 160 may be used by the communication unit 140 to perform communication with the rechargeable device 200 or may be used instead of the transmit antenna 110 to transfer power to the rechargeable device 200.

Here, the resonant frequency of the second transmit antenna 160 may be changed to be different from the resonant frequency of the transmit antenna 110 and the controller 130 may detect the resonant frequency of the rechargeable device 200 and control the second matching circuit 170 to match the resonant frequency of the second transmit antenna 160 with the resonant frequency of the rechargeable device 200.

Through the above configuration of the wireless charging apparatus 100, the wireless charging apparatus 100 can match the resonant frequency of the transmit antenna 110 with the resonant frequency of the alternating magnetic field to receive power at optimal efficiency and can also match the resonant frequency of the second transmit antenna 160 with the resonant frequency of the rechargeable device 200, guaranteeing optimal power transfer efficiency.

The following is a description of a wireless charging method using the wireless charging system described above.

FIG. 7 is a flowchart illustrating a wireless charging method according to an embodiment of the present invention.

As shown in FIG. 7, first, a position of the wireless charging apparatus 100 at which the magnitude of alternating magnetic field is maximized is determined while moving the wireless charging apparatus 100 to various positions (S210). Here, the wireless charging apparatus 100 may collect an alternating magnetic field using the transmit antenna 110 and determine the intensity of the alternating magnetic field at the current position by measuring the amount of power received from the collected alternating magnetic field through the controller 130. The measured intensity of the alternating magnetic field may be presented to the user through a display unit or a speaker.

When the optimal position of the wireless charging apparatus 100 has been determined through such a position determination procedure, the wireless charging apparatus 100 is located at the determined position (S220).

Thereafter, the wireless charging apparatus 100 determines whether or not a rechargeable device 200, which needs to be charged, is present adjacent to the wireless charging apparatus 100 through a search process (S230). When such a rechargeable device 200 is found, the wireless charging apparatus 100 detects a resonant frequency of the alternating magnetic field and matches the resonant frequency of the transmit antenna 110 with the detected resonant frequency of the alternating magnetic field (S240).

Thereafter, the wireless charging apparatus 100 charges the rechargeable device 200 using power received from the alternating magnetic field (S250). Here, the wireless charging apparatus 100 may simultaneously charge the battery 150 and may also receive power from the completely charged battery 150 and transfer the received power to the rechargeable device 200.

FIG. 8 is a flowchart illustrating a wireless charging method according to another embodiment of the present invention.

As shown in FIG. 8, first, a rechargeable device 200, which needs to be charged, is brought near the wireless charging apparatus 100 to allow the controller 130 to detect the rechargeable device 200 (S310). Thereafter, the amount of power received from an alternating magnetic field collected through the transmit antenna 110 is measured while moving the wireless charging apparatus 100 and the rechargeable device 200 to determine the optimal position (S320).

Thereafter, the controller 130 controls the matching circuit 120 to detect a resonant frequency of the alternating magnetic field and matches the resonant frequency of the transmit antenna 110 with the detected resonant frequency (S330).

Thereafter, the wireless charging apparatus 100 transfers power received from the alternating magnetic field to the rechargeable device 200 to charge the rechargeable device 200.

As shown in FIG. 9, first, a position of the wireless charging apparatus 100 at which the magnitude of alternating magnetic field is maximized is determined while moving the wireless charging apparatus 100 (S410). Here, the wireless charging apparatus 100 may collect an alternating magnetic field using the transmit antenna 110 and determine the intensity of the alternating magnetic field at the current position by measuring the amount of power received from the collected alternating magnetic field through the controller 130. The measured intensity of the alternating magnetic field may be presented to the user through a display unit or a speaker.

When the optimal position of the wireless charging apparatus 100 has been determined through such a position determination procedure, the wireless charging apparatus 100 is located at the determined position (S420).

Thereafter, the wireless charging apparatus 100 determines whether or not a rechargeable device 200, which needs to be charged, is present adjacent to the wireless charging apparatus 100 through a search process (S430). When such a rechargeable device 200 is found, the wireless charging apparatus 100 detects a resonant frequency of the alternating magnetic field and matches the resonant frequency of the transmit antenna 110 with the detected resonant frequency of the alternating magnetic field (S440). In addition, the wireless charging apparatus 100 detects the resonant frequency of the rechargeable device 200 and matches the resonant frequency of the second transmit antenna 160 with the detected resonant frequency of the rechargeable device 200 (S450).

Thereafter, the wireless charging apparatus 100 transfers power received from the alternating magnetic field to the rechargeable device 200 at the matched resonant frequency to charge the rechargeable device 200 (S460).

As is apparent from the above description, according to the present invention, it is possible to charge a load device using energy of alternating magnetic fields.

In addition, it is possible to charge various portable devices even when an external power source is not available.

Although exemplary embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible without departing from essential characteristics of the invention.

Thus, the embodiments described herein are explanatory without limiting the technical spirit of the invention and should not be used to limit the scope of the invention.

The scope of the invention should be determined by reasonable interpretation of the appended claims and all changes coming within the equivalency range of the invention are intended to be embraced in the scope of the invention.

Claims

A wireless charging apparatus for charging a rechargeable device, the wireless charging apparatus comprising:

an antenna for collecting an alternating magnetic field to receive power;

a matching circuit for changing a resonant frequency of the antenna; and

a controller for matching the resonant frequency of the antenna with a resonant frequency of the alternating magnetic field using the matching circuit,

wherein the controller determines whether or not the rechargeable device is adjacent to the wireless charging apparatus and transfers power to the rechargeable device using the antenna upon determining that the rechargeable device is adjacent to the wireless charging apparatus.
The wireless charging apparatus according to claim 1, further comprising a communication unit for performing communication with the adjacent rechargeable device.
The wireless charging apparatus according to claim 2, wherein the communication unit transmits a search signal at intervals of a first time,

the communication unit determines whether or not a response signal corresponding to the search signal has been received from the rechargeable device within a second time after transmission of the search signal and then retransmits, upon determining that the response signal has not been received from the rechargeable device within the second time after transmission of the search signal, a search signal at intervals of the first time after a third time elapses, and

the communication unit notifies the controller of reception of the response signal upon determining that the response signal has been received from the rechargeable device within the second time after transmission of the search signal.
The wireless charging apparatus according to claim 2, further comprising a second antenna having a different resonant frequency from the antenna.
The wireless charging apparatus according to claim 4, further comprising a second matching circuit for controlling the resonant frequency of the second antenna.
The wireless charging apparatus according to claim 5, wherein the controller matches the resonant frequency of the second antenna with a resonant frequency of the rechargeable device using the second matching circuit.
A wireless charging system comprising:

a rechargeable device including a rechargeable battery and

a wireless charging apparatus for collecting an alternating magnetic field to receive power and transferring the power as an RF signal to the rechargeable device,

the wireless charging apparatus including:

an antenna for collecting an alternating magnetic field and transmitting the RF signal;

a matching circuit for changing a resonant frequency of the antenna; and

a controller for matching the resonant frequency of the antenna with a resonant frequency of the alternating magnetic field using the matching circuit,

the rechargeable device further including:

a device antenna for receiving the RF signal transmitted from the antenna;

an impedance matcher for changing impedance of the device antenna to change a resonant frequency of the device antenna; and

a charging unit for supplying power produced through conversion of the RF signal to the rechargeable battery,

wherein the controller determines whether or not the rechargeable device is adjacent to the wireless charging apparatus and transfers power to the rechargeable device using the antenna upon determining that the rechargeable device is adjacent to the wireless charging apparatus.
The wireless charging system according to claim 7, wherein the wireless charging apparatus further includes an apparatus communication unit for performing communication with the adjacent rechargeable device,

wherein the rechargeable device further includes a device communication unit for communicating with the apparatus communication unit.
The wireless charging system according to claim 8, wherein the apparatus communication unit transmits a search signal at intervals of a first time,

the apparatus communication unit determines whether or not a response signal corresponding to the search signal has been received from the device communication unit within a second time after transmission of the search signal and then retransmits, upon determining that the response signal has not been received from the device communication unit within the second time after transmission of the search signal, a search signal at intervals of the first time after a third time elapses, and

the apparatus communication unit notifies the controller of reception of the response signal upon determining that the response signal has been received from the device communication unit within the second time after transmission of the search signal.
The wireless charging system according to claim 8, wherein the wireless charging apparatus further includes a second antenna having a different resonant frequency from the antenna, and

wherein the rechargeable device further includes a second device antenna corresponding to the second antenna.
The wireless charging system according to claim 10, further comprising a second matching circuit for controlling the resonant frequency of the second antenna.
The wireless charging system according to claim 11, wherein the controller matches the resonant frequency of the second antenna with a resonant frequency of the rechargeable device using the second matching circuit.
A wireless charging method using an alternating magnetic field, the wireless charging method comprising:

measuring power received from an alternating magnetic field collected through an antenna and determining a position at which a wireless charging apparatus is to be arranged;

searching for a rechargeable device that is adjacent to the wireless charging apparatus arranged at the determined position;

detecting a resonant frequency of the alternating magnetic field using a matching circuit;

changing a resonant frequency of the antenna so as to match with the detected resonant frequency; and

transferring the power received from the alternating magnetic field to the rechargeable device.
The wireless charging method according to claim 13, wherein detecting the resonant frequency of the alternating magnetic field includes changing the resonant frequency of the antenna using the matching circuit and searching for a frequency at which the power received from the alternating magnetic field is maximized.
The wireless charging method according to claim 13, wherein searching for the rechargeable device further includes:

transmitting a search signal from a communication unit at intervals of a first time;

awaiting reception of a response signal corresponding to the search signal from the rechargeable device during a second time after transmission of the search signal from the communication unit;

retransmitting, when the reception signal has not been received within the second time, the search signal at intervals of the first time after a third time elapses; and

transmitting, by a controller, power to the rechargeable device which has transmitted the response signal using the antenna when the response signal has been received within the second time.
The wireless charging method according to claim 13, further comprising:

detecting a resonant frequency of the rechargeable device using a second matching circuit; and

matching a resonant frequency of the second antenna with the resonant frequency of the rechargeable device,

wherein the wireless charging apparatus transmits power to the rechargeable device or communicates with the rechargeable device using the second antenna.
A wireless charging method using an alternating magnetic field, the wireless charging method comprising:

detecting, by a communication unit, a rechargeable device when the rechargeable device is arranged adjacent to a wireless charging apparatus;

measuring power received from an alternating magnetic field collected through an antenna and determining positions at which the wireless charging apparatus and the rechargeable device are to be arranged;

detecting a resonant frequency of the alternating magnetic field using a matching circuit;

changing a resonant frequency of the antenna so as to match with the detected resonant frequency; and

transferring the power received from the alternating magnetic field to the rechargeable device.
The wireless charging method according to claim 17, wherein detecting the resonant frequency of the alternating magnetic field includes changing the resonant frequency of the antenna using the matching circuit and searching for a frequency at which the power received from the alternating magnetic field is maximized.
The wireless charging method according to claim 17, wherein detecting the rechargeable device further includes:

transmitting a search signal from the communication unit at intervals of a first time;

awaiting reception of a response signal corresponding to the search signal from the rechargeable device during a second time after transmission of the search signal from the communication unit;

retransmitting, when the reception signal has not been received within the second time, the search signal at intervals of the first time after a third time elapses; and

transmitting, by a controller, power to the rechargeable device which has transmitted the response signal using the antenna when the response signal has been received within the second time.
The wireless charging method according to claim 17, further comprising:

detecting a resonant frequency of the rechargeable device using a second matching circuit after detecting the rechargeable device; and

matching a resonant frequency of the second antenna with the resonant frequency of the rechargeable device,

wherein the wireless charging apparatus transmits power to the rechargeable device or communicates with the rechargeable device using the second antenna.