KR101968601B1 - Method and apparatus for control of wireless power transmission - Google Patents

Abstract

A method and apparatus for controlling wireless power transmission is provided. The output power of the source device is wirelessly transmitted to the target device via the resonator. The source device senses a change in the current of the output power, and requests the target device to confirm the status. The source device determines the state of the wireless power transmission based on the change in current and the state of the target device. The source device controls the wireless power transmission operation to the target device according to the determined state of the wireless power transmission.

Description

≪ Desc / Clms Page number 1 > METHOD AND APPARATUS FOR CONTROL OF WIRELESS POWER TRANSMISSION < RTI ID =

The following embodiments relate to a method and apparatus for wirelessly transmitting power.

A method and apparatus for controlling wireless power transmission is disclosed.

Wireless power refers to the energy delivered from a wireless power transmission device to a wireless power reception device through magnetic coupling. Thus, a wireless power charging system includes a source device that wirelessly transmits power and a target device that wirelessly receives power. At this time, the source device may be referred to as a wireless power transmission device. The target device may also be referred to as a wireless power receiving device.

The source device has a source resonator, and the target device has a target resonator. A magnetic coupling or a resonant coupling may be formed between the source resonator and the target resonator.

One source device may transmit power to a plurality of target devices.

When a plurality of target devices are simultaneously accessed into the resonator region of the source device or when power is applied to the source device when a plurality of target devices are present in the resonator region of the source device, Data collision occurs by the devices, and a normal charging operation may not be performed.

An embodiment of the present invention can provide an apparatus and method for measuring a current of an output power based on a current flowing in a power conversion unit and receiving a state of target devices to determine a wireless power transmission state.

An embodiment of the present invention can provide an apparatus and method for adjusting power output wirelessly according to a determined wireless power transmission state.

According to an aspect of the present invention, there is provided a power conversion apparatus including a control unit for determining output power, a power conversion unit for outputting the output power, a resonator for wirelessly transmitting the output power to the target device, and a power detector for detecting the current of the output power Wherein the control unit senses a change in the current through the power detector, receives a status of the target device from the target device, and determines a status of the wireless power transmission based on the change in the current and the status of the target device And controls the wireless power transmission operation according to the state of the wireless power transmission.

The controller may regard the change as not occurring when the change of the current occurs within a predetermined time.

The controller may consider that the change does not occur when the change of the current occurs within a predetermined range.

The controller may request the target device status of the target device when the change of the current occurs for a predetermined time or more.

The control unit may control the wireless power transmission operation by adjusting the output power based on the state of the target device.

When the current changes to a current corresponding to a load when the target device is removed, the control unit can control the wireless power transmission operation by stopping the output of the output power.

The current may correspond to the load when the target device is in the constant voltage mode.

The state of the target device may indicate that the target device is in a constant voltage mode.

The control unit may control the wireless power transmission operation by controlling the output power.

The target device may be a plurality of target devices.

The control unit may receive the status of the target device for each of the plurality of target devices and may determine a status of the wireless power transmission based on the change of the current and the states of the plurality of target devices.

The current can be reduced.

Wherein the states of the plurality of target devices include a state in which a charging state of some or all of the plurality of target devices is changed from a constant current mode to a constant voltage CV mode, A state indicating that the devices have been removed, and a state indicating that one or more of the plurality of target devices are buffered.

The current may increase,

The plurality of target devices may include an added target device,

The control unit may control the wireless power transmission operation by increasing the output power so that the output power is transmitted to the added target device.

According to another aspect of the present invention, there is provided a method of wirelessly transmitting output power to a target device, sensing a change in current of the output power, receiving a status of the target device from the target device, Determining a state of the wireless power transmission based on a change in the state of the target device and a state of the target device, and controlling a wireless power transmission operation in accordance with the determined state of the wireless power transmission .

When the change of the current occurs within a predetermined time, it can be regarded that the change does not occur.

If the change of the current occurs within a certain range, it can be regarded that the change does not occur.

The control method of the wireless power transmission may further include a step of requesting the target device for the status of the target device when the change of the current occurs for a predetermined time or longer.

The step of controlling the wireless power transmission operation may comprise adjusting the output power based on a state of the target device.

The step of controlling the wireless power transmission operation may include stopping the output of the output power when the current changes to a current corresponding to a load when the target device is removed.

The current may correspond to the load when the target device is in the constant voltage mode.

The state of the target device may indicate that the target device is in a constant voltage mode.

The step of controlling the wireless power transmission operation may include the step of controlling the wireless power transmission operation by controlling the output power.

The receiving of the status of the target device may be performed for each of the plurality of target devices.

Determining the state of the wireless power transmission may include determining a state of the wireless power transmission based on the change of the current and the states of the plurality of target devices.

The plurality of target devices may include an added target device.

The step of controlling the wireless power transmission operation may include increasing the output power such that the output power is transmitted to the added target device.

There is provided an apparatus and method for measuring a current of an output power based on a current flowing in a power conversion unit and receiving a state of target devices to determine a wireless power transmission state.

An apparatus and method for adjusting power output wirelessly in accordance with a determined wireless power transmission status are provided.

1 illustrates a wireless power transmission and charging system in accordance with one embodiment.
Figure 2 shows the distribution of the magnetic field in the resonator and feeder according to one embodiment.
3 is a wireless power transmission apparatus according to one embodiment.
4 is a view showing a distribution of a magnetic field in a resonator according to feeding of a feeding part according to an embodiment.
5 illustrates a multi-target device communication environment according to one example.
6 illustrates modes of a wireless power transmission and charging system according to an example.
7 is a structural diagram of a source device according to an embodiment.
8 is a structural diagram of a target device according to an embodiment.
Figure 9 illustrates variation of the target load according to one example.
10 shows a configuration of a source device and a power detector according to an example.
11 illustrates a battery load variation according to an example.
12 illustrates the variation of the charging current according to an example.
13 is a flow diagram of a method for detecting a load for a wireless power transmission and determining a state of a wireless power transmission in accordance with an embodiment.
14 is a flow chart of a method of controlling wireless power transmission in accordance with one embodiment.
FIG. 15 illustrates a case where a current change is detected within a predetermined time according to an example.
FIG. 16 illustrates a case where a current change over a predetermined time is detected according to an example.
17 illustrates a case in which a load is removed during charging of a single target device according to an example.
FIG. 18 illustrates a case where a target device is removed during charging of a single target device according to an example.
FIG. 19 illustrates a mode change of the target device being charged according to an example.
FIG. 20 illustrates a case where the mode of the target device is changed during charging of a single target device according to an example.
FIG. 21 illustrates a case where a mode of a target device changes during charging of multiple target devices according to an example.
FIG. 22 illustrates a case where the load is removed during charging of the multi-target devices according to an example.
23 illustrates a case where target devices are removed during charging of multiple target devices according to an example.
Figure 24 illustrates a case where the charge state of one or more of the target devices during a charge of multiple target devices according to an example has been changed to reduce PA current.
25 illustrates a case where the PA current increases during charging of multiple target devices according to an example.
FIG. 26 illustrates a case where an overcurrent occurs during charging of the target device according to an example.
27 shows an electric vehicle charging system according to an embodiment.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to or limited by the embodiments. Like reference symbols in the drawings denote like elements.

1 illustrates a wireless power transmission and charging system in accordance with one embodiment.

Referring to FIG. 1, a wireless power transmission and charging system according to one embodiment includes a source device 110 and a target device 120.

The target device 120 may be any one of a portable terminal, a notebook, a television, various electromagnetic devices, a hearing aid, and an electric vehicle. That is, the target device 120 may be mounted on any one of a portable terminal, a notebook, a television, various electromagnetic devices, a hearing aid, and an electric vehicle.

The source device 110 may include an AC / DC converter 111, a power detector 113, a power conversion unit 114, a control and communication unit 115, and a source resonator 116.

The target device 120 may include a target resonator 121, a rectification section 122, a DC / DC converter 123, a switch section 124, a charging section 125, and a control and communication section 126.

The AC / DC converter 111 rectifies an AC voltage of several tens Hz band outputted from a power supply 112 to generate a DC voltage. The AC / DC converter 111 can output a DC voltage of a certain level or adjust the output level of the DC voltage according to the control of the control and communication unit 115. [

The power detector 113 detects the output current and voltage of the AC / DC converter 111 and transmits information on the detected current and voltage to the control and communication unit 115. The power detector 113 may also detect the input current and voltage of the power conversion unit 114. [

The power conversion unit 114 can generate power by converting a DC voltage of a certain level into an AC voltage by a switching pulse signal of several KHz to several tens MHz. That is, the power conversion section 114 converts the DC voltage supplied to the power amplifying section into the AC voltage using the reference resonance frequency F _Ref , thereby generating the communication power or the charging power used in the plurality of target devices have. Here, the communication power may mean a small power of 0.1 to 1 mWatt, and the charging power may mean a large power of 1 mWatt to 200 Watt consumed in the device load of the target device. As used herein, the term " charging " may be used to mean powering a unit or element charging power. The term " charging " may also be used to mean powering a unit or element that consumes power. Here, the unit or element includes, for example, a battery, a display, a sound output circuit, a main processor, and various sensors.

In the present specification, the " reference resonance frequency " can be used to mean a resonance frequency that the source device 110 basically uses. Also, the " tracking frequency " can be used to mean a resonance frequency adjusted according to a preset method.

The control and communication unit 115 detects reflected waves for the "communication power" or the "charging power", and performs mismatching between the target resonator 121 and the source resonator 116 based on the detected reflected waves. . The control and communication unit 115 can detect mismatching by detecting the envelope of the reflected wave, and can detect mismatching by detecting the amount of power of the reflected wave. The control and communication unit 115 can calculate the voltage standing wave ratio (VSWR) based on the level of the output voltage of the source resonator 116 or the power conversion unit 114 and the voltage level of the reflected wave, If the voltage standing wave ratio is smaller than the predetermined value, it can be determined that the mismatching has been detected. If the voltage standing wave ratio is smaller than the predetermined value, the control and communication unit 115 may calculate the power transmission efficiency for each of the predetermined N tracking frequencies. If the power transmission efficiency among the N tracking frequencies is the best, F _Best can be determined, and the F _Ref can be adjusted to the F _Best .

Also, the control and communication unit 115 can adjust the frequency of the switching pulse signal. The frequency of the switching pulse signal can be determined by the control and communication unit 115. The control and communication unit 115 can generate the modulation signal for transmission to the target device 120 by controlling the power conversion unit 114. [ In other words, the control and communication unit 115 can transmit various messages to the target device through the in-band communication. In addition, the control and communication unit 115 can detect the reflected wave, It is possible to demodulate a signal received from the base station.

The control and communication unit 115 may generate a modulated signal for performing in-band communication through various methods. The control and communication unit 115 can generate a modulated signal by turning on / off the switching pulse signal. Also, the control and communication unit 115 can perform delta-sigma modulation to generate a modulated signal. The control and communication unit 115 can generate a pulse width modulation signal having a constant envelope.

Meanwhile, the control and communication unit 115 may perform out-band communication using a communication channel. The control and communication unit 115 may include a communication module such as Zigbee and Bluetooth. The control and communication unit 115 may transmit and receive data to and from the target device 120 through out-band communication.

The source resonator 116 transfers the electromagnetic energy to the target resonator 121. That is, the source resonator 116 can transmit " communication power " or " charging power " to the target device 120 through magnetic coupling with the target resonator 121.

The target resonator 121 receives electromagnetic energy from the source resonator 116. That is, the target resonator 121 may receive " communication power " or " charging power " from the source device 110 through magnetic coupling with the source resonator 116. In addition, the target resonator 121 may receive various messages from the source device via in-band communication.

The rectifying unit 122 rectifies the AC voltage to generate a DC voltage. That is, the rectifying section 122 can rectify the received AC voltage to the target resonator 121. [

The DC / DC converter 123 adjusts the level of the DC voltage output from the rectifying unit 122 to match the capacity of the charger 125. For example, the DC / DC converter 123 can adjust the level of the DC voltage output from the rectifying unit 122 to 3 to 10 Volts.

The switch unit 124 is turned on / off under the control of the control and communication unit 126. When the switch unit 124 is turned off, the control and communication unit 115 of the source device 110 detects the reflected wave. That is, when the switch portion 124 is turned off, the magnetic coupling between the source resonator 116 and the target resonator 121 can be removed.

The charging unit 125 may include a battery. The charging unit 125 can charge the battery using the DC voltage output from the DC / DC converter 123. [

The control and communication unit 126 may perform in-band communication for transmitting and receiving data using a resonant frequency. The control and communication unit 126 may detect a signal between the target resonator 121 and the rectifying unit 122 and demodulate the received signal or detect the output signal of the rectifying unit 122 to demodulate the received signal. That is, the control and communication unit 126 can demodulate the received message through the in-band communication. Further, the control and communication section can modulate the signal to be transmitted to the source device 110 by adjusting the impedance of the target resonator 121. [ The control and communication unit may also modulate a signal to be transmitted to the source device 110 through on / off of the switch unit 124. [ In a simple example, the control and communication unit 126 may increase the impedance of the target resonator 121 so that the reflected wave is detected in the control and communication unit 115 of the source device 110. Depending on whether or not the reflected wave is generated, the control and communication unit 115 of the source device 110 can detect the binary number " 0 " or " 1 ".

The control and communication unit 126 stores the type of the target device, the manufacturer information of the target device, the model name of the target device, the battery type of the target device, Quot ;, " information on the characteristics of the target resonator of the target device ", " information on the used frequency band of the target device ", " amount of power consumed by the target device & To the source device 110, a response message including " a unique identifier of the target device ", or " version or specification information of the product of the target device.

Meanwhile, the control and communication unit 126 may perform out-band communication using a communication channel. The control and communication unit 126 may include a communication module such as Zigbee or Bluetooth. The control and communication unit 126 may transmit and receive data to and from the source device 110 through out-band communication.

The control and communication unit 126 receives the wake-up request message from the source device 110, detects the amount of power received at the target resonator, and transmits information about the amount of power received at the target resonator to the source device 110. [ (110). Here, the information on the amount of power received by the target resonator is " input voltage value and current value of the rectifying section 122 ", " output voltage value and current value of the rectifying section 122 & 123) output voltage value and current value ".

In FIG. 1, the control and communication unit 115 may set the resonance bandwidth of the source resonator 116. Depending on the setting of the resonance bandwidth of the source resonator 116, the Q-factor Q _S of the source resonator 116 can be determined.

In addition, the control and communication unit 126 may set the resonance bandwidth of the target resonator 121. Depending on the setting of the resonance bandwidth of the target resonator 121, the Q-factor Q _D of the target resonator 121 can be determined. At this time, the resonant bandwidth of the source resonator 116 may be set to be wider or narrower than the resonant bandwidth of the target resonator 121. Through communication, the source device 110 and the target device 120 can share information about the resonant bandwidth of the source resonator 116 and the target resonator 121, respectively. The Q-factor Q _S of the source resonator 116 may be set to a value greater than 100 when a higher power is required from the target device 120 than the reference value. In addition, when a lower power than the reference value is required from the target device 120, the Q-factor Q _S of the source resonator 116 can be set to a value smaller than 100.

In a resonant mode wireless power transmission, the resonant bandwidth is an important factor. Qt is a cue factor that takes account of both a change in distance between the source resonator 116 and the target resonator 121, a change in resonant impedance, an impedance mismatching, a reflection signal, etc. Qt is expressed by Equation (1) Inverse relationship.

는 대역폭,

는 공진기 사이의 반사 손실, BWS는 소스 공진기(116)의 공진 대역폭, BWD는 타겟 공진기(121)의 공진 대역폭을 나타낸다.In Equation (1), f ₀ is the center frequency,

Bandwidth,

BWS is the resonant bandwidth of the source resonator 116, and BWD is the resonant bandwidth of the target resonator 121. [

On the other hand, in the wireless power transmission, the efficiency U of the wireless power transmission can be defined as shown in Equation (2).

는 소스 공진기(115)에서의 반사계수,

는 타겟 공진기(121)에서의 반사계수,

는 공진 주파수, M은 소스 공진기(116)와 타겟 공진기(121) 사이의 상호 인덕턴스, R_S는 소스 공진기(116)의 임피던스, R_D는 타겟 공진기(121)의 임피던스, Q_S는 소스 공진기(116)의 큐-팩터, Q_D는 타겟 공진기(121)의 큐-팩터, Q_K는 소스 공진기(116)와 타겟 공진기(121) 사이의 에너지 커플링에 대한 큐-팩터이다. Where K is the coupling coefficient for the energy coupling between the source resonator 115 and the target resonator 121,

Is the reflection coefficient at the source resonator 115,

The reflection coefficient at the target resonator 121,

Is the resonant frequency, M is the source resonator 116 and the target resonator 121, the impedance of the mutual inductance, R _S is the source resonator 116 between, R _D is the impedance of the target cavity 121, Q _S is the source resonator ( queue 116) - factor, Q _D is the queue of the target resonator 121-factor, Q _K is the queue for the energy coupling between the source resonator 116 and the target cavity (121) is a factor.

Referring to Equation (2) above, the queue factors are highly related to the efficiency of the wireless power transmission.

Thus, the queue-factor is set to a high value to increase the efficiency of the wireless power transmission. At this time, when Q _S and Q _D are set to an excessively high value, a change in coupling coefficient K for energy coupling, a change in distance between the source resonator 116 and the target resonator 121, a change in resonance impedance, The efficiency of the wireless power transmission may decrease due to matching or the like.

Also, if the resonance bandwidth of each of the source resonator 116 and the target resonator 121 is set too narrow to increase the efficiency of the wireless power transmission, impedance mismatching and the like can easily occur even with a small external influence. Considering impedance mismatch, Equation (1) can be expressed as Equation (3).

When the resonance bandwidth or the bandwidth of the impedance matching frequency between the source resonator 115 and the target resonator 121 is maintained in an unbalance relationship, A decrease in the efficiency of the wireless power transmission due to a change in distance, a change in resonance impedance, impedance mismatch, or the like can be reduced. According to Equations (1) and (3), if the resonance bandwidth between the source resonator 116 and the target resonator 121 or the bandwidth of the impedance matching frequency is maintained in an unbalance relationship, the cue- The unbalance relationship between the cue-effectors of the target resonator 121 is maintained.

In Figs. 2 to 4, " resonator " includes a source resonator and a target resonator.

Figure 2 shows the distribution of the magnetic field in the resonator and feeder according to one embodiment.

When the resonator is supplied with power through a separate feeder, a magnetic field is generated in the feeder and a magnetic field is generated in the resonator.

Referring to FIG. 2 (a), a magnetic field 230 is generated as the input current flows in the feeder 210. The direction 231 of the magnetic field in the feeder 210 and the direction 233 of the magnetic field in the outside have opposite phases to each other. An induced current is generated in the resonator 220 by the magnetic field 230 generated in the feeder 210. The direction of the induced current is opposite to the direction of the input current.

A magnetic field 240 is generated in the resonator 220 by an induced current. The direction of the magnetic field has the same direction inside the resonator 220. Therefore, the direction 241 of the magnetic field generated inside the feeder 210 by the resonator 220 and the direction 243 of the magnetic field generated from the outside of the feeder 210 have the same phase.

As a result, when the magnetic field generated by the feeder 210 and the magnetic field generated by the resonator 220 are combined, the strength of the magnetic field is weakened inside the feeder 210, do. Therefore, when power is supplied to the resonator 220 through the feeder 210 having the structure as shown in FIG. 2, the intensity of the magnetic field at the center of the resonator 220 is weak, and the strength of the magnetic field at the periphery is strong. If the distribution of the magnetic field on the resonator 220 is not uniform, it is difficult to perform the impedance matching because the input impedance varies from time to time. In addition, since the wireless power transmission is good in the portion where the magnetic field strength is strong and the wireless power transmission is not performed in the portion where the strength of the magnetic field is weak, the power transmission efficiency is decreased on average.

3 is a wireless power transmission apparatus according to an embodiment.

Referring to FIG. 3 (a), the wireless power transmission apparatus may include a resonator 310. The resonator 310 may include a capacitor 311. The feeding portion 320 may be electrically connected to both ends of the capacitor 311. [

(b) is a diagram more specifically showing the structure of (a). At this time, the resonator 310 may include a first transmission line, a first conductor 341, a second conductor 342, and at least one first capacitor 350.

A first capacitor 350 is inserted in series between the first signal conductor portion 331 and the second signal conductor portion 332 in the first transmission line such that the electric field is applied to the first capacitor 350). Generally, the transmission line includes at least one conductor at the top and at least one conductor at the bottom, where current flows through the conductor at the top and the conductor at the bottom is electrically grounded. In this specification, the conductor on the upper part of the first transmission line is divided into the first signal conductor part 331 and the second signal conductor part 332, and the conductor under the first transmission line is called the first ground conductor part 333).

(b), the resonator may have the form of a two-dimensional structure. The first transmission line includes a first signal conductor portion 331 and a second signal conductor portion 332 at an upper portion thereof and a first ground conductor portion 333 at a lower portion thereof. The first signal conductor portion 331 and the second signal conductor portion 332 and the first ground conductor portion 333 are disposed facing each other. The current flows through the first signal conductor portion 331 and the second signal conductor portion 332.

One end of the first signal conductor portion 331 is shorted to the first conductor 341 and the other end is connected to the first capacitor 350 as shown in FIG. One end of the second signal conductor portion 332 is grounded to the second conductor 342 and the other end is connected to the first capacitor 350. As a result, the first signal conductor portion 331, the second signal conductor portion 332 and the first ground conductor portion 333, and the conductors 341 and 342 are connected to each other so that the resonator has an electrically closed loop structure . Here, the 'loop structure' includes a circular structure, a polygonal structure such as a rectangle, and the like, and the term 'having a loop structure' means that it is electrically closed.

The first capacitor 350 is inserted in the middle of the transmission line. More specifically, a first capacitor 350 is inserted between the first signal conductor portion 331 and the second signal conductor portion 332. In this case, the first capacitor 350 may have the form of a lumped element and a distributed element. In particular, a dispersed capacitor in the form of a dispersive element can comprise zigzag shaped conductor lines and a dielectric with a high dielectric constant present between the conductor lines.

As the first capacitor 350 is inserted into the transmission line, the source resonator may have the characteristics of a metamaterial. Here, a metamaterial is a material having a special electrical property that can not be found in nature, and has an artificially designed structure. The electromagnetic properties of all materials present in nature have inherent permittivity or permeability, and most materials have a positive permittivity and a positive permeability.

In most materials, the right-hand rule applies to electric fields, magnetic fields and pointing vectors, so these materials are called RHM (Right Handed Material). However, the meta-material is a material having a permittivity or permeability that does not exist in the natural world, and may be an epsilon negative material, an MNG (mu negative material), a DNG (double negative) material, index material, left-handed material, and the like.

At this time, when the capacitance of the first capacitor 350 inserted as a lumped element is properly determined, the source resonator can have a metamaterial characteristic. In particular, by appropriately adjusting the capacitance of the first capacitor 350, the source resonator can have a negative permeability, so that the source resonator can be called an MNG resonator. The criterion for determining the capacitance of the first capacitor 350 may vary. A criterion allowing the source resonator to have the property of a metamaterial, a premise that the source resonator has a negative permeability at the target frequency, or a source resonator having a Zeroth-Order Resonance characteristic And the capacitance of the first capacitor 350 can be determined under the premise of at least one of the above-mentioned premises.

The MNG resonator may have a zeroth-order resonance characteristic with a resonant frequency at a frequency of zero propagation constant. Since the MNG resonator may have a zero resonance characteristic, the resonance frequency may be independent of the physical size of the MNG resonator. That is, as will be described later, it is sufficient to appropriately design the first capacitor 350 in order to change the resonant frequency in the MNG resonator, so that the physical size of the MNG resonator can be changed.

Also, since the electric field in the near field is concentrated in the first capacitor 350 inserted in the transmission line, the magnetic field in the near field is dominant due to the first capacitor 350. Since the MNG resonator can have a high Q-factor by using the first capacitor 350 of the lumped element, the power transmission efficiency can be improved. For reference, the queue-factor represents the ratio of the reactance to the degree of resistance or ohmic loss in the wireless power transmission, the larger the queue-factor, the greater the efficiency of the wireless power transmission .

Further, although not shown in (b), a magnetic core passing through the MNG resonator may be further included. Such a magnetic core can perform a function of increasing a power transmission distance.

the feeder 320 may include a second transmission line, a third conductor 371, a fourth conductor 372, a fifth conductor 381, and a sixth conductor 382 .

The second transmission line includes a third signal conductor portion 361 and a fourth signal conductor portion 362 at the top and a second ground conductor portion 363 at the bottom. The third signal conductor portion 361 and the fourth signal conductor portion 362 and the second ground conductor portion 363 are disposed facing each other. The current flows through the third signal conductor portion 361 and the fourth signal conductor portion 362.

One end of the third signal conductor portion 361 is shorted to the third conductor 371 and the other end is connected to the fifth conductor 381 as shown in FIG. One end of the fourth signal conductor portion 362 is grounded to the fourth conductor 372, and the other end is connected to the sixth conductor 382. The fifth conductor 381 is connected to the first signal conductor portion 331 and the sixth conductor 382 is connected to the second signal conductor portion 332. The fifth conductor 381 and the sixth conductor 382 are connected in parallel at both ends of the first capacitor 350. At this time, the fifth conductor 381 and the sixth conductor 382 may be used as an input port for receiving an RF signal.

As a result, the third signal conductor portion 361, the fourth signal conductor portion 362 and the second ground conductor portion 363, the third conductor 371, the fourth conductor 372, the fifth conductor 381, The sixth conductor 382 and the resonator 310 are connected to each other so that the resonator 310 and the feeding portion 320 have an electrically closed loop structure. Here, the 'loop structure' includes a circular structure, a polygonal structure such as a rectangle, and the like. When an RF signal is input through the fifth conductor 381 or the sixth conductor 382, the input current flows to the feeding part 320 and the resonator 310, and the resonance is generated by the magnetic field generated by the input current. Gt; 310 < / RTI > The direction of the input current flowing in the feeding part 320 and the direction of the induced current flowing in the resonator 310 are formed to be the same so that the strength of the magnetic field is strengthened at the center of the resonator 310, Lt; / RTI >

Since the input impedance can be determined by the area of the region between the resonator 310 and the feeder 320, a separate matching network is not required to perform the matching of the input impedance with the output impedance of the power amplifier. Even when a matching network is used, the structure of the matching network can be simplified since the input impedance can be determined by adjusting the size of the feeding portion 320. [ A simple matching network structure minimizes the matching loss of the matching network.

The third conductor 371, the fourth conductor 372, the fifth conductor 381 and the sixth conductor 382 may have the same structure as the resonator 310. That is, when the resonator 310 has a loop structure, the feeding portion 320 may also have a loop structure. When the resonator 310 has a circular structure, the feeding portion 320 may have a circular structure.

4 is a view showing a distribution of a magnetic field in a resonator according to feeding of a feeding part according to an embodiment.

Feeding in a wireless power transmission implies supplying power to the source resonator. Also, in wireless power transmission, feeding can mean supplying AC power to the rectifying section. (a) shows the direction of the input current flowing in the feeding part and the direction of the induced current induced in the source resonator. (A) shows the direction of the magnetic field generated by the input current of the feeding portion and the direction of the magnetic field generated by the induced current of the source resonator. (a) is a more simplified representation of the resonator 310 and the feeding portion 320 of FIG. (b) shows an equivalent circuit of the feeding part and the resonator.

(a), the fifth conductor or the sixth conductor of the feeding portion can be used as the input port 410. The input port 410 receives an RF signal. The RF signal can be output from the power amplifier. The power amplifier can increase or decrease the amplitude of the RF signal according to the needs of the target device. The RF signal input from the input port 410 may be displayed in the form of an input current flowing in the feeding part. The input current flowing through the feeding section flows clockwise along the transmission line of the feeding section. However, the fifth conductor of the feeding portion is electrically connected to the resonator. More specifically, the fifth conductor is coupled to the first signal conductor portion of the resonator. Therefore, the input current flows not only in the feeding part but also in the resonator. In the resonator, the input current flows counterclockwise. A magnetic field is generated by an input current flowing in the resonator, and an induced current is generated in the resonator by the magnetic field. The induced current flows clockwise in the resonator. At this time, the induced current can transfer energy to the capacitor of the resonator. A magnetic field is generated by the induced current. (a), the input current flowing in the feeder and the resonator is indicated by a solid line, and the induced current flowing in the resonator is indicated by a dotted line.

The direction of the magnetic field generated by the current can be determined by the right-hand rule. The direction 421 of the magnetic field generated by the input current flowing in the feeding portion and the direction 423 of the magnetic field generated by the induced current flowing in the resonator are the same in the feeding portion. Thus, the intensity of the magnetic field inside the feeding portion is strengthened.

In the region between the feeding portion and the resonator, the direction 433 of the magnetic field generated by the input current flowing in the feeding portion and the direction 431 of the magnetic field generated by the induced current flowing in the source resonator are opposite in phase. Therefore, in the region between the feeding part and the resonator, the intensity of the magnetic field is weakened.

In a loop type resonator, the intensity of the magnetic field is generally weak at the center of the resonator and strong at the outer portion of the resonator. However, referring to (a), since the feeding portion is electrically connected to both ends of the capacitor of the resonator, the direction of the induced current of the resonator becomes the same as the direction of the input current of the feeding portion. Since the direction of the induced current of the resonator is the same as the direction of the input current of the feeding portion, the strength of the magnetic field is strengthened inside the feeding portion and the strength of the magnetic field outside the feeding portion is weakened. As a result, at the center of the loop-shaped resonator, the strength of the magnetic field is enhanced due to the feeding portion, and the strength of the magnetic field at the outer portion of the resonator is weakened. Therefore, the intensity of the magnetic field can be uniform throughout the resonator.

On the other hand, since the efficiency of the power transmission from the source resonator to the target resonator is proportional to the intensity of the magnetic field generated in the source resonator, the power transmission efficiency can be increased as the strength of the magnetic field is strengthened at the center of the source resonator.

(b), the feeding portion 440 and the resonator 450 may be represented by an equivalent circuit. The input impedance Z _{in, which} is seen when the resonator side is viewed in the feeding part 440, can be calculated by Equation (4).

Here, M denotes a mutual inductance between the feeding part 440 and the resonator 450, ω denotes a resonance frequency between the feeding part 440 and the resonator 450, Means the impedance seen when looking at the side. Z _in is proportional to the mutual inductance M. Therefore, Z _in can be controlled by adjusting the mutual inductance between the feeding portion 440 and the resonator 450. The mutual inductance M may be adjusted according to the area of the area between the feeding part 440 and the resonator 450. The area of the area between the feeding part 440 and the resonator 450 can be adjusted according to the size of the feeding part 440. Since Z _in can be determined according to the size of the feeding unit 440, a separate matching network is not required to perform impedance matching and impedance matching of the power amplifier.

The target resonator and the feeding portion included in the wireless power receiving apparatus may have a distribution of the magnetic field as described above. The target resonator receives radio power from the source resonator through magnetic coupling. At this time, an induced current can be generated in the target resonator through the received radio power. The magnetic field generated by the induced current in the target resonator can generate the induced current again in the feeding part. At this time, when the target resonator and the feeding portion are connected as in the structure of (a), the direction of the current flowing in the target resonator becomes the same as the direction of the current flowing in the feeding portion. Therefore, the strength of the magnetic field can be strengthened inside the feeding portion, and the strength of the magnetic field in the region between the feeding portion and the target resonator can be weakened.

5 illustrates a multi-target device communication environment according to one example.

The wireless power transmission and charging system 500 may include one source device 510 and one or more target devices 520.

One source device 510 may transmit power to a plurality of target devices 520. [

The source device 510 may be the source device 110 described above with reference to FIG. The target device 520 may be the target device 120 described above with reference to FIG.

The source device 510 may output an anti-collision data command and power.

The target devices 520 may have batteries.

When a plurality of target devices 520 simultaneously approach the resonator region of the source device 510 or when a plurality of target devices 520 are present in the resonator region of the source device 510, When the power is turned on, data collision may occur by a plurality of target devices 520 during the initial connection process. The normal charging operation may not be performed due to the collision.

6 illustrates modes of a wireless power transmission and charging system according to an example.

The wireless power transmission and charging system 500, in terms of software, can have three types of modes. The three types of modes may be the standby mode, the connection mode, and the transmission (charging) mode.

(1) The standby mode means a state in which the target device 520 does not exist within the power transmission distance of the source device 510.

(2) The connection mode is a mode in which the source device 510 confirms the information such as 1) the type of the target device 520, the amount of power used, and the serial number through the initial connection between the source device 510 and the target device 520 And 2) the target device 520 is in a normal transfer (charge) control mode. The initial connection may occur when the target device 520 is present within the power transmission distance of the source device 510.

In the connection mode, a plurality of target devices 520 can request a connection to one source device 510 at the same time. In the following embodiment, when a plurality of target devices 520 concurrently request a connection to the source device 510, a method for always processing 1: 1 communication between the source device 510 and the target device 520 is performed Is described in detail.

(3) The transmission (charging) mode means a state in which the source device 510 and the target device 520 communicate with each other through a slot allocated by the source device 510 to the target device 520 in the connection mode.

On the side of the source device 510, the overall operation of the wireless power transmission and charging system 500 can be distinguished. For a single target device 520, the standby mode-connected mode-transfer (charge) mode-standby mode is repeated. 1 (source device 510) according to the following embodiments: In a wireless power transmission and charging system of N (target device 520), complex and repetitive operations may occur. For example, in a state where some target devices 520 among the plurality of target devices 520 are in the charging mode, some of the target devices 520 may have already completed charging, and the new target device 520 Connection can be attempted.

7 is a structural diagram of a source device according to an embodiment.

The source device 510 includes a control and communication unit 710, a power supply 720, a power detector 730, an oscillator 740, a power amplifier (PA) 750, a matching control unit 755, (I.e., a transmission (TX) resonator) 760.

The control and communication unit 710 may be a control and communication unit 115. The power supply 720 may be a power supply 112 and an AC / DC converter 111. The power detector 730 may be a power detector 113. The PA 750 may be a power conversion unit 114. The source resonator 760 may be a source resonator 116.

The control and communication unit 710 may include a power supply control unit 712. Alternatively, the source device 510 may further include a supply power control unit 712.

The oscillator 760 can generate a signal having a frequency in the range of several Khz to several tens MHz. The above signal may be the switching pulse signal described above with reference to Fig. The signal generated by the oscillator 760 may be applied to the PA 750. The oscillator 760 may change the frequency and matching schematics of the signal. The control and communication unit 710 may control the oscillator 760 to change the frequency and matching scheme of the signal generated by the oscillator 760.

The power supply 720 may be a Switching Mode Power Supply. The power supply control unit 712 can control the power supply unit 720. The supply power control unit 712 can apply the supply power to the PA 750 by controlling the power supply 720. [ The power that power supply 720 applies to PA 750 is termed PA supply power. The power supply control unit 712 may control the power supply 720 to adjust the voltage applied by the power supply 720 to the PA 750. [ The voltage that power supply 720 applies to PA 750 is termed PA supply voltage. As the power supply 720 regulates the PA supply voltage, the current supplied to the PA 750 can be regulated.

The PA 750 may be a variable switching amplifier. PA 750 may be designed as an E-class switching amplifier. The output power of the PA 750 may be determined by the frequency of the signal applied from the oscillator 760 and the supply power applied from the power supply 720. [ And the power output from the PA 750 is referred to as PA power. In addition, the PA current is the current supplied to the PA 750 as the supply power control unit 712 controls the power supply 720. The PA voltage is the voltage of the PA power.

The source resonator 760 transmits the PA power to the target device 520 as electromagnetic energy.

The matching controller 755 may be a matching circuit. The matching controller 755 may change the matching impedance and the matching frequency. The control and communication unit 710 may control the matching control unit 755 to change the matching impedance and the matching frequency. The power detector 730 can detect the current and voltage of the power supplied by the power supply 720 and transmit information on the detected current and voltage to the control and communication unit 710. The power detector 730 may detect the PA power (or PA current) and the PA voltage and may transmit information about the detected PA power (or PA current and PA output voltage) to the control and communication unit 710 have. The power detector 730 may monitor the power supply to the target device 520 by detecting a change in load and mode of the target device 520. [ The power detector 730 may use the detected load change and mode change to demodulate the load modulation of the target device 520.

8 is a structural diagram of a target device according to an embodiment.

The target device 520 includes a target resonator 810, a matching control unit 815, a rectification unit 820, a modulation / demodulation unit 830, a DC / DC converter 840, a power detector 860, a control and communication unit 870, A switch portion 880 and a load 890. [

The target resonator 810 may be the target resonator 121. The rectifying unit 820 may be a rectifying unit 122. The DC / DC converter 840 may be a DC / DC converter 123. The control and communication unit 870 may be a control and communication unit 126. The switch unit 880 may be the switch unit 124. [ The load 890 may be the charging unit 125.

The target resonator 810 may receive the electromagnetic energy output from the source resonator 760 of the source device 510. That is, the target resonator 810 receives power from the source device 510 through magnetic coupling with the source resonator 760. The received power may be used as " communication current " or " charging power ". In addition, the target resonator 810 may receive various messages from the source device 510 via in-band communication.

The matching control unit 815 can match the impedance between the target resonator 810 and the rectifying unit 820. The matching controller 815 may be a matching circuit. The matching controller 815 may change the matching impedance and the matching frequency. The control and communication unit 870 may control the matching control unit 815 to change the matching impedance and the matching frequency.

The rectification section 820 can generate a DC voltage by rectifying the alternating voltage output from the target resonator 810. [ That is, the rectifying unit 820 can rectify the AC voltage received through the target resonator 810. [

The DC / DC converter 840 can adjust the level of the DC voltage output from the rectifier 820 according to the capacity of the load 890. For example, the DC / DC converter 840 can adjust the level of the DC voltage output from the rectifying part to 3 to 10V.

The power detector 860 can detect the output power and the output voltage of the DC / DC converter 840. The power detector 860 can transmit the output power and the output voltage of the detected DC / DC converter 840 to the control and communication unit 870.

The switch unit 880 can be turned ON / OFF under the control of the control and communication unit 870. For example, when the target device 520 (or the load 890) is buffered, the switch portion 880 may be turned off. When the switch unit 880 is turned off, the control and communication unit 710 of the source device 510 can detect the power that the target device 520 receives. That is, when the switch portion 880 is turned off, the magnetic coupling between the source resonator 760 and the target resonator 810 can be eliminated.

The load 890 may include a battery. The load 890 may include a charging unit 125. The load 890 can be charged using the DC voltage output from the DC / DC converter 840.

The control and communication unit 870 can perform in-band communication with the source device 510 using the resonance frequency. The control and communication unit 870 can use the modulation / demodulation unit 830 for in-band communication. The control and communication unit 870 may include a modulation and demodulation unit 830 and the function of the modulation and demodulation unit 830 may be performed by the control and communication unit 870.

The modulation and demodulation unit 830 can detect a signal transmitted between the target resonator 810 and the rectification unit 820 or an output signal of the rectification unit 820 and demodulate the signal received by the target device 520. [ That is, the modem unit 830 can demodulate the signal received by the target device 520 through the in-band communication. Also, the modulation / demodulation unit 830 can modulate the signal transmitted to the source device 510 by adjusting the impedance of the target resonator 810. The modulation / demodulation unit 830 can modulate a signal transmitted to the source device 510 through ON / OFF of the switch unit 880.

Figure 9 illustrates variation of the target load according to one example.

In the following, types for control of power to be transmitted wirelessly will be described.

Wireless transmission power control includes: 1) initial power control, 2) power control for target load changes, and 3) power control for changes from CC mode to CV mode.

1) The initial power control may be to control and transmit the wireless transmit power when the source device 510 and the target device 520 initiate a connection.

In a wireless power transmission system, a difference in efficiency between the source resonator 760 and the target resonator 810 may occur for each vendor or product. Therefore, an initial power control considering the efficiency difference between the source resonator 760 and the target resonator 810 is performed, and power according to the initial power control is transmitted, so that the required power of the target device 520 can be appropriately transmitted .

2) It is also possible to change the number of target devices 520 during charging or change the battery charging mode of the target device 520 (e.g., from a constant current (CC) mode to a constant voltage ) Occurs, the target load is changed.

The target load means the load measured at the output end of the PA 750, i.e., the load of the target connected to the output end. That is, the target load may mean a load applied to the output terminal of the PA 750.

The change in the target load may be accomplished by: 1) changing the number of target devices 520 being charged through the source device 510; or 2) changing the battery charging mode of the target device 520 From CV mode to CV mode).

When the target load is changed, power corresponding to the changed load must be transmitted by the power control for the target load change. The power control for the change of the target load may mean that the power is controlled and transmitted in accordance with the varying load.

Five important principles that are used to detect changes in the load 890 of the target device 520 at the PA 750 are described below.

1) The current of the PA 750 (i.e., the PA current) is detected.

2) Detects the change of the target load by the change of the detected PA current.

3) If the PA current increases during charging, load is added.

The charging state is a state in which the source device 510 recognizes the target device 520 and supplies the target device 520 with necessary power. The control and communication unit 710 (or the power supply control unit 712) controls the power supply 720 to cause the power supply 720 to provide the PA 750 with the controlled PA supply power. The control and communication unit 710 can confirm the supplied current and the charged state through the communication. The power detector 730 detects a change in PA current. The control and communication unit 710 can determine that the load 890 is added when the PA current increases beyond the reference current value. The control and communication unit 710 recognizes the added load 890 and controls the PA power.

4) If the PA current is low during charging, the load will be low.

When the source device 510 is in the charging state and the PA current detected by the power detector 730 is lower than the current value when charging, the control and communication unit 710 can determine that the target load has changed, The state of the target device 520 can be checked to control the PA supply power.

5) When the PA current is below the reference current at the beginning of charging or charging, there is no target device 520.

In the absence of the target device 520, only the source resonator 790 appears as a load on the PA 750. [ That is, the control and communication unit 710 can determine the presence or absence of the target device 520 according to the output (for example, the PA current) of the PA 750 based on the PA current when there is no load.

In the following, conditions for the source device 510 to control the power and detect the load will be described.

In order to supply the required power to the target device 520 in response to a change in the load 910, the PA 760 must output power matching the target load. In order for the PA 760 to output power to meet the target load, the following two conditions must be satisfied.

1) Impedance Matching Condition: The source-side impedance shall meet the matching condition for the load impedance. Here, the source-side impedance means 1) the impedance of the source device 510 including the source resonator 760 and 2) the target resonator 810.

Whether or not the above matching is satisfied can be confirmed through a reflection coefficient value. The reflection coefficient can be calculated according to the following equation (5).

는 반사 계수이다. V_i는 입사 파(incident wave)이다. V_r은 반사 파(reflected wave)이다. Z_o는 소스 임피던스이다. Z_L은 부하 임피던스이다.here,

Is the reflection coefficient. V _i is an incident wave. V _r is the reflected wave. Z _o is the source impedance. Z _L is the load impedance.

2) Resonant frequency conditions between the source device 510 and the target device 520: The resonant frequencies of the source resonator 760 and the target resonator 810 should be the same.

The principle of detecting the target load will be described below.

The control and communication unit 710 can detect a change in the load 890 of the target device 520 by detecting the PA supply power supplied by the power supply 720. [ The load 890 viewed at the output end of the PA 750 may be represented by the sum of the loads 890 of one or more target devices 520 when the impedance between the source resonator 790 and the target resonator 810 is matched . 9, if the load 890 of the first target device 910 is 3W and the load 890 of the second target device 920 is 3W, then the output of the PA 750 of the source device 510 The total target load viewed from the stage is 6W.

As shown in Equation 6 below, the output power of the PA 750 (i.e., the PA power) can be determined by a change in the output load.

Here, Pwr represents the output power. R represents the output load (i.e., the target load).

As R becomes smaller, Pwr increases, and when R increases, Pwr decreases. Based on this theory, a change in load in wireless charging can be detected. Detecting a change in the target load due to the PA current change of the PA 750 can be an important parameter to determine whether to control the PA power and communicate with the target device 520. [

10 shows a configuration of a source device and a power detector according to an example.

10, a specific configuration for detecting the PA current through the configuration of the power detector 730 is disclosed.

The power detector 730 may detect the PA current and transmit the detected PA current to the control and communication unit 710.

The AC / DC power supply 1010 may represent a power supply 720.

The control and communication unit 710 may be supplied with the power Vcc necessary for operation from the AC / DC power source 1010. The control and communication unit 710 may control the AC / DC power supply 1010 to adjust the PA supply power that the AC / DC power supply 1010 outputs to the power supply 720. The control and communication unit 710 may control the oscillator 760 to change the frequency and matching scheme of the signal generated by the oscillator 760.

The power detector 730 may include a comparator 1020 and a first resistor 1060. The power detector 730 may further include a second resistor 1030, a third resistor 1040, and a current detector 1050.

The first terminal of the first resistor 1060, the output of the AC / DC power supply 1010, and the + terminal of the comparator 1020 can be connected to each other. The second terminal of the first resistor 1600, the input of the PA 750, and the - terminal of the comparator 1020 may be connected to each other.

PA current flows through the first resistor 1060.

The comparator 1020 outputs a voltage to both terminals (+ terminal and - terminal) to the control and communication unit 710. The voltage across both stages of the comparator 1020 and the voltage across both stages of the first resistor 1060 are the same. The control and communication unit 710 can know the size of the first resistor. The control and communication unit 710 then calculates the current I _s flowing through the first resistor 1060 (i.e., the PA current) through the resistance value of the first resistor 1060 and the voltage across both stages of the comparator 1020 . In addition, the control and communication unit 710 can detect the target load based on the calculated PA current.

The second resistor 1030 may connect the first terminal of the first resistor 1060 and the + terminal of the comparator 1020. The third resistor 1040 may couple the second terminal of the first resistor 1060 and the negative terminal of the comparator 1020. The second resistor 1030 and the third resistor 1040 can adjust the voltage across both stages of the comparator 1020.

11 illustrates a battery load variation according to an example.

The x-axis of graph 1100 represents time. The y-axis represents current / voltage.

In graph 1100, the solid line represents the voltage / cell. The dotted line indicates the charging current.

Prior to charging, the control and communication portion 870 can verify the voltage or temperature of the battery (i.e., load 890).

The charging of the battery can be divided into three steps.

Step 1 1110 is a constant current (CC) charging step. In the CC charging step, the maximum charging current is applied to the battery until the charging voltage cell voltage limit is reached.

In the CC charging step, a charging current of about 0.5 to 0.7C of the battery capacity is applied. Where C represents the capacitance. For example, when the capacity of the battery is 1000 mAh, a charging current of about 500 mA to 700 mA is applied to the battery for charging. The charging voltage gradually increases from 4.15V to 4.2V.

CC charging can be classified into pre-charging where a charging voltage of 3V or less is applied and rapid charging where a charging voltage of 3V or more is applied.

Step 2 1120 is a constant voltage (CV) charging step. When the charging voltage reaches the maximum cell voltage, the charge state of the battery approaches the full charge and the charge charge starts to drop. In the CV charging step, the charging voltage maintains a constant voltage between 4.15V and 4.2V.

The charging voltage can be calculated according to the following equation (7).

Here, the resistance is the sum of the internal resistance of the battery and the circuit resistance.

As shown in Equation (7), if the resistance is large, the constant-voltage charging time becomes long.

At point 1040 where the charge current is less than 3% of the rated current, the CV charging terminates.

When the charge current becomes less than a reference value (e.g., 3% of the rated current) as the amount of charge in the battery increases, the control and communication unit 870 can detect the lowered PA current through the power detector 730, Can be terminated.

Step 3 1130 is a topping charge step. Intermittent topping charge of about once per 500 hours is applied to the battery.

12 illustrates the variation of the charging current according to an example.

The x-axis of the graph 1200 represents time. and the y-axis represents the value of the charging current.

The value of charge current 1210 over time is shown.

The load 890 is charged in the CC mode for a predetermined time (e.g., 50 minutes). At this time, the charge current is referred to as CC mode reference current. That is, the CC mode reference current is the value of the charge current 1210 when the load 890 is in the charge mode CC mode. The charge voltage gradually increases to about 4.2V.

Thereafter, the charging current 1210 gradually decreases to approach 20 to 30 mA. As the charging mode of the target device 520 changes, the charging current 1210 may have a specific value. The time when the charging current 1210 approaches 20 to 30 mA can be determined as the charging end. Charge current 1210 may decrease for a period of time (e.g., 3 hours), and load 890 may typically be charged to 0.5 to 1.0C.

The CV mode reference current is a value of the charging current 1210 when the charging mode of the load 890 is considered to be changed from the CC mode to the CV mode. The target device buffer reference current 1210 is the value of the charge current 1210 when the target device 520 is considered buffered. The target device removal reference current 520 is the value of the charging current 1210 when the target device 520 is considered to have been removed.

13 is a flow diagram of a method for detecting a load for a wireless power transmission and determining a state of a wireless power transmission in accordance with an embodiment.

In step 1310, the control and communication unit 710 determines the PA power. The control and communication unit 710 may adjust the PA supply voltage by controlling the power supply 720. [ The power supply 720 applies the PA supply voltage to the PA 750 under the control of the control and communication unit 710. PA 750 outputs the determined PA power. The source resonator 790 transmits the PA power to the target device 520 wirelessly.

The target device 520 may be plural. At this time, the target load may be the sum of the loads 890 of the plurality of target devices 520.

In step 1320, the control and communication unit 710 senses a change in the PA current. The power detector 730 detects the current of the PA power (i.e., PA current). The control and communication unit 710 may sense a change in the PA current through the power detector 730. [ For example, the PA current may change as the target device 520 changes from the CC charging mode to the CV charging mode.

In step 1330, the control and communication unit 710 detects the target load based on the change in the PA current.

In step 1340, the control and communication unit 710 determines the state of the wireless power transmission based on the detected target load. For example, the control and communication unit 710 may terminate the charging of the target device 520 if the detected current is lower than a predefined value. The control and communication unit 710 may also adjust the PA power based on the detected target load.

Table 1 below shows the relationship between the change in PA current sensed in step 1320 and the state of the wireless power transmission in step 1340. [

PA  Current change Wireless power transfer status PA current changes within a certain time. A change in the position of the target device 520, a change in the position of the charging pad, or an external influence occurs. PA current has occurred over a certain period of time. Charging failure of the target device 520 or other problems occur. When the source device 510 is a single target device 520 charging mode (or CC charging mode), the PA current decreases. The charging target device 520 is removed, or the target device 520 changes from the CC mode to the CV mode. When the source device 510 is in the charging mode of the multiple devices 520, the PA current is reduced to a certain level. The target device 520 being charged changes from the CC mode to the CV mode, or is fully charged. When the source device 510 is in the charging mode of the multiple devices 520, the PA current is reduced to a current corresponding to the target load when the target device 520 is absent The presence or absence of the target device 520 is confirmed through communication between the source device 510 and the target device 520. [ Increasing the PA current when the source device 510 is a single target device 520 charging mode or a multiple target device 520 charging mode. Target device 520 is added. PA Detects overcurrent. Operation for protection of the source device 510.

14 is a flow chart of a method of controlling wireless power transmission in accordance with one embodiment.

In step 1410, the control and communication unit 710 determines the PA power. The control and communication unit 710 may adjust the supply voltage applied to the PA 750 by controlling the power supply 720. [ The power supply 720 applies the supply voltage to the PA 750 under the control of the control and communication unit 710. PA 750 outputs the determined PA power. The source resonator 790 transmits the PA power to the target device 520 wirelessly.

The target device 520 may be plural. At this time, the target load may be the sum of the loads 890 of the plurality of target devices 520.

In step 1420, the control and communication unit 710 senses a change in the PA current. The power detector 730 can detect the current of the PA power (i.e., the PA current), and the control and communication unit 710 can sense the change in the PA current through the power detector 730. [ The control and communication unit 710 can detect the target load based on the change in the PA current.

The control and communication unit 710 can determine the wireless power transmission state based on the change in the PA current (or the detected target load).

In step 1430, the control and communication unit 710 requests the target device 520 for the status of the target device 520 (hereinafter referred to as target device status).

In step 1440, the control and communication unit 710 receives the target device status from the target device 520. If the state of the target device 520 is not received even after a predetermined time has elapsed, the control and communication unit 710 can regard the response from the target device 520 as being absent.

In step 1450, the control and communication unit 710 confirms the received target device status.

In step 1460, the control and communication unit 710 determines the wireless power transmission state based on the change in the PA current (or the detected target load) and the state of the target device 520. [ The control and communication unit 710 controls the source device 510 (i.e., the wireless power transmission operation of the source device 510) according to the determined wireless power transmission status.

In the following, specific methods of determining the wireless power transmission status and controlling the source device 510 will be described in detail with reference to Figs. 15 to 26. Fig.

FIG. 15 illustrates a case where a current change is detected within a predetermined time according to an example.

The x-axis of graph 1500 represents time. The y-axis represents current. The detected level 1510 of PA current is shown and points 1520 and 1530 where a change in PA current is detected within a certain level are shown.

1) the position of the target device 520 changes during charging, 2) the position of the charging pad used by the source device 510 for charging changes, and 3) Device 520 changes, or 4) other external influences occur, the PA current may change over a period of time. Therefore, in step 1420, the control and communication unit 710 can consider that no change has occurred when the change in the PA current occurs within a certain period of time. Alternatively, in step 1420, the control and communication unit 710 may consider that no change has occurred when the change of the PA current occurs within a certain range. The control and communication unit 710 can regard the change of the PA current as if no change occurred within 1) a certain range and 2) within a certain time.

Alternatively, in step 1420, the control and communication unit 710 can consider that no change has occurred when the PA current returns to the reference value within a certain time, and can maintain the PA power as it is.

FIG. 16 illustrates a case where a current change over a predetermined time is detected according to an example.

The x axis of graph 1600 represents time. The y-axis represents current. The detected level of the PA current 1610 is shown and points 1620 and 1630 where a change in the PA current is sensed within a certain level are shown. Also, the communication process between the source device 510 and the target device 520 is indicated. 16 and in the following embodiments, Tx means the source device 510 and Rx means the target device 520. [

1) the position of the target device 520 changes during charging, 2) the position of the charging pad used by the source device 510 for charging changes, and 3) Device 520 changes, or 4) other external influences occur, the PA current may change over a period of time.

The control and communication unit 710 requests the status of the target device 520 through ID communication or the like in step 1430. If the change in the current has occurred continuously for more than a predetermined time .

In step 1460, the control and communication unit 710 may either 1) reset or recharge the target device 520, or 2) control the PA 750 (For example, the PA 750 is turned off), 3) an alarm is generated to inform the occurrence of the abnormality, or 4) an alarm is generated to request confirmation of the charged state of the target device 520. The control unit and communication unit 710 can also control the wireless power transmission operation by adjusting the PA power based on the state of the received target device 520. [

17 illustrates a case in which a load is removed during charging of a single target device according to an example.

The first state diagram 1700 indicates that the source device 510 is charging the target device 520. The source device 510 is in a single terminal charging mode (or CC mode) charging one target device 520.

The second state diagram 1750 shows a state in which a single target device 520 is missing.

When the target device 520 is removed, the target load reflects only the load of the source resonator 760. Therefore, PA current corresponding to the load of the source resonator 760 is outputted from the PA 750. [

FIG. 18 illustrates a case where a target device is removed during charging of a single target device according to an example.

The x-axis of graph 1800 represents time. The y-axis represents current. The detected level 1810 of PA current is shown and the point 1820 where a change in PA current is detected within a certain level is shown. At point 1820, the PA current decreases while the target device 520 is being charged. Also, the communication process between the source device 510 and the target device 520 is indicated.

The reduced PA current at point 1820 is the current corresponding to the target load due to the removal of the target device 520. [ The reduced PA current at point 1820 may be a target device removal reference current. That is, in step 1420, the control and communication unit 710 senses that the PA current has decreased to a current corresponding to the target load when the target device 520 is removed.

Also, because the target device 520 has been removed, in step 1430, a target device status request is not delivered to the target device 520. [ The source device 510 may send a response character (ACK) transmission command for the target device status request to the target device 520 at which time a response to the response character transmission command is not transmitted from the target device 520 Do not. Also, in step 1440, receiving a response to the target device status request, the target devices 520 do not transmit the target device status.

In step 1460, the control and communication unit 710 may interrupt the output of the PA power. That is, the control and communication unit 710 is configured to: 1) change the PA current to a current corresponding to the target load when the target device 520 is removed in step 1430; and 2) in step 1440, When the status of the target device is not transmitted from the device 520, the wireless power transmission operation can be controlled by stopping the output of the PA power.

The contents described with reference to Figs. 17 and 18 can also be applied when the target device 520 is buffered. If the target device 520 is buffered, the target device 520 may not perform further charging, and the source device 510 may consider the target device 520 to be removed from the charging object. In this case, in step 1440, the target device 520 may transmit to the control and communication unit 710 that the target device status is buffered. If the target device state is a buffered state, in step 1460, the control and communication unit 710 may stop outputting the PA power.

FIG. 19 illustrates a mode change of the target device being charged according to an example.

The first graph 1900 shows a state in which a single target device 520 charges in the CC mode. At this time, the load 890 of the target device 890 is a (CC) load of 3W.

As the target device 890 is charged, the charging mode of the target device 520 changes from CC mode to CV mode. When the charge mode changes to the CV mode, the load 890 increases.

The second graph 1950 shows a state in which a single target device 520 charges in the CV mode. At this time, the load 890 of the target device 520 is (CV) load of 1W.

Therefore, when the charging mode of the target device 520 changes from the CC mode to the CV mode, the target load increases. Thus, in accordance with the increased target load, the PA current output from PA 750 decreases.

FIG. 20 illustrates a case where the mode of the target device is changed during charging of a single target device according to an example.

The x-axis of the graph 2000 represents the time. The y-axis represents current. The level 2010 of the detected PA current is shown and a point 2020 where a change in PA current is detected within a certain level is shown. The initially detected level of PA current indicates that the target device 520 is being charged. At point 2020, the PA current decreases while the target device 520 is being charged. The reduced PA current at point 2020 may be a CC mode reference current. Also, the communication process between the source device 510 and the target device 520 is indicated.

The PA current reduced at point 2020 is the current corresponding to the target load when the charging mode of the target device 520 changes from CC mode to CV mode. That is, the PA current reduced at point 2020 corresponds to the target load when target device 520 is in CV mode.

When the source device 510 is in a single target device charging mode, at step 1420, the control and communication unit 710 senses a decrease in PA current. At this time, the reduced PA current may correspond to the load 890 when the target device 520 is in the CV mode. In step 1440, the target device state received by the control and communication unit 710 may indicate that the target device 520 is in the CV mode. Alternatively, the target device state may indicate that the target device 520 has changed from the CC mode to the CV mode.

In step 1460, the control and communication unit 710 controls the wireless power transmission operation by controlling the PA power. That is, step 1460 may include controlling the wireless power transmission operation by controlling the PA power.

FIG. 21 illustrates a case where a mode of a target device changes during charging of multiple target devices according to an example.

The x-axis of graph 2100 represents time. The y-axis represents current. The detected level 2110 of PA current is shown and point 2120 where a change in PA current is detected within a certain level. The initially detected level of PA current indicates that a plurality of target devices 520 are being charged. Also, the communication process between the source device 510 and the plurality of target devices 520 is indicated.

At point 2120, the PA current is reduced by changing the state of one or more of the target devices 520 of the plurality of target devices 520. [ For example, one or more target devices 520 may be removed or buffered. Alternatively, one or more target devices 520 may change to CC mode.

The reduced PA current at point 2120 is a current corresponding to the sum of the target loads of the target devices 520 that have changed states. That is, in step 1420, the control and communication unit 710 may sense that the PA current has decreased.

In step 1430, the control and communication unit 710 requests a target device status for each of the plurality of target devices 520. [ The control and communication unit 710 may request the ID of the target device 520 to each of the plurality of target devices 520 to identify target device states of the different target devices 520. [

In step 1440, the control and communication unit 710 may receive the target device status from each of the plurality of target devices 520. If the state of the specific target device 520 is not received even after a predetermined time has elapsed, the control and communication unit 710 can regard the response from the target device 520 that has not received the status.

In step 1450, the control and communication unit 710 may verify the status of each of the plurality of target devices 520 using the received target device status.

In step 1460, the control and communication unit 710 determines whether the PA current changes (or the detected target load) and the states of the plurality of target devices 520 (or the state of each of the plurality of target devices 520) To determine the wireless power transmission state. That is, step 1460 includes determining that the control and communication unit 710 determines the wireless power transmission state based on the changes in the PA current (or the detected target load) and the states of the plurality of target devices 520 can do.

FIG. 22 illustrates a case where the load is removed during charging of the multi-target devices according to an example.

The first graph 2200 indicates that the source device 510 is charging two target devices 2210 and 2220. The source device 510 is in a multiple terminal charging mode to charge a plurality of target devices 520. [ At this time, the total load 2230 (or the target load) may be the sum of the load 890 of the first target device 2210 and the load 890 of the second target device 2220. For example, if the load 890 of the first target device 2210 is 3W and the load 890 of the second target device 2220 is 3W, then the total load 2230 is 6W.

The second graph 2250 shows the state in which the second target device 2220 is removed.

As the second target device 2220 is removed, the total load 2230 decreases to 3W. The total load 2240 represents the reduced total load.

The control and communication unit 710 can determine whether some (or all) of the plurality of target devices 520 exist by setting a reference value of the PA current. That is, the control and communication unit 710 can determine whether the target devices 520 exist based on the PA current. That is, when 3W of PA power is output at a specific target load, the PA power is reduced to less than 3W when the load is removed during PA output. When the PA power is reduced, the control and communication unit 710 can determine the status of the target devices 520 based on the level at which the PA power is dropped.

23 illustrates a case where target devices are removed during charging of multiple target devices according to an example.

The x-axis of the graph 2300 represents time. The y-axis represents current. The detected level 2310 of PA current is shown and the point 2320 where a change in PA current is detected within a certain level is shown. At point 2320, the PA current decreases while the plurality of target devices 520 are being charged. Also, the communication process between the source device 510 and the target devices 520 has been indicated.

The reduced PA current at point 2320 is a current corresponding to the target load when all target devices 520 are removed. The reduced PA current at point 2320 may be current when there is no charging load (or target load). The reduced PA current at point 2320 may be a target device removal reference current. That is, in step 1420, the control and communication unit 710 senses that the PA current has decreased to a current corresponding to the target load when the target devices 520 are removed.

Also, because the target device 520 has been removed, in step 1430, a target device status request is not delivered to each of the target devices 520. [ The source device 510 may send an acknowledgment (ACK) transmission command for the target device status request to each of the target devices 520 from which the response to the response character transmission command It is not transmitted. Also, in step 1440, receiving a response to the target device status request, the target devices 520 do not transmit the target device status.

In step 1460, the control and communication unit 710 may interrupt the output of the PA power. That is, the control and communication unit 710 changes the current to the current corresponding to the target load when the PA current is removed from all of the plurality of target devices 520 in step 1430, and 2) The wireless power transmission operation can be controlled by stopping the output of the PA power when the status of the target device is not transmitted from the plurality of target devices 520. [

The contents described with reference to Figs. 22 and 23 can also be applied when a plurality of target devices 520 are buffered. When a plurality of target devices 520 are buffered, each of the plurality of target devices 520 may not perform further charging, and the source device 510 may remove a plurality of target devices 520 from the charge target Can be regarded as being. In this case, in step 1440, each of the plurality of target devices 520 may transmit to the control and communication unit 710 that the target device state is a buffer state. If the target device state of all the target devices 520 is in a buffered state, then in step 1460, the control and communication unit 710 may stop outputting the PA power.

Figure 24 illustrates a case where the charge state of one or more of the target devices during a charge of multiple target devices according to an example has been changed to reduce PA current.

The x-axis of graph 2400 represents time. The y-axis represents current. The detected level 2410 of PA current is shown and the point 2420 where a change in PA current is detected within a certain level is shown.

The initially detected level of PA current may indicate that a plurality of target devices 520 are being charged. At point 2420, the PA current decreases while the plurality of target devices 520 are being charged. Also, the communication process between the source device 510 and the plurality of target devices 520 is indicated.

The reduced PA current at point 2420 may indicate that the charging mode of one or more target devices 520 has changed. That is, the reduced PA current at point 2420 may correspond to the changed target load by changing one or more of the charging modes of the plurality of target devices 520.

When the source device 510 is in the multiple target device charging mode, at step 1420, the control and communication unit 710 may sense a decrease in PA current (or PA power). The control and communication unit 710 can recognize that the target device 520 or the fully charged target device 520 has changed to the CV mode among the plurality of target devices 520. [ Accordingly, in steps 1420-1440, the control and communication unit 710 communicates with the plurality of target devices 520 to ascertain the target device status of each of the target devices 520. [

In step 1440, the target device states of the target devices 520 received by the control and communication unit 710 may indicate one or more of the following states 1 to 4 below.

State 1: The charge state of some target devices 520 among the plurality of target devices 520 changes from CC mode to CV mode.

State 2: The charging state of all the target devices 520 among the plurality of target devices 520 changes from the CC mode to the CV mode.

State 3: At least one of the plurality of target devices 520 is removed.

State 4: At least one of the plurality of target devices 520 is buffered.

In step 1460, the control and communication unit 710 controls the wireless power transfer operation by controlling the PA power based on the target device states of the identified plurality of target devices 520. [ That is, step 1460 may include controlling the wireless power transmission operation by controlling the PA power.

The control and communication unit 710 may transmit an OFF command to the charged target device 520 among the plurality of target devices 520 to prevent the buffered target device 520 from receiving power.

25 illustrates a case where the PA current increases during charging of multiple target devices according to an example.

The x-axis of the graph 2500 represents time. The y-axis represents power. The level 2510 of the detected PA current is shown and the point 2520 where a change in the PA current is sensed within a certain level is shown.

The initially detected level of PA current may indicate that a plurality of target devices 520 are being charged. At point 2520, the PA current increases while the plurality of target devices 520 are being charged. Also, the communication process between the source device 510 and the plurality of target devices 520 is indicated.

The increased PA current at point 2520 may indicate that the target device 520 has been added. That is, the increased PA current at point 2420 may correspond to the changed target load by adding one or more target devices 520 to the plurality of target devices 520. [

When the source device 510 is in the multiple target device charging mode, at step 1420, the control and communication unit 710 may sense an increase in PA current (or PA power). The control and communication unit 710 can know that there is an added target device 520 through the increased PA current. Thus, in steps 1420-1440, the control and communication unit 710 communicates with the plurality of target devices 520 including the added target device 520 to determine the ID of each of the target devices 520, You can check the device status.

The control and communication unit 710 can recognize information on the presence and required power of each of the plurality of target devices 520 through the target device status. The control and communication unit 710 may assign a control ID to each of the plurality of target devices 520 including the added target device 520 so as to control each of the plurality of target devices 520. [

In step 1460, the control and communication unit 710 may control the wireless power transfer operation by controlling the PA power so that the added target device 510 can be powered on. That is, step 1460 may include increasing the PA power such that power is transferred to the added target device 510.

FIG. 26 illustrates a case where an overcurrent occurs during charging of the target device according to an example.

The x-axis of graph 2600 represents time. The y-axis represents power. The level 2610 of the detected PA current is shown and the point 2620 where a change in the PA current is sensed within a certain level is shown. At point 2620, the PA current increases above the overcurrent level 2630 while one or more target devices 520 are being charged. The PA current 2640 when the source device 510 operates to control the target device 520 is shown and the communication process between the source device 510 and the plurality of target devices 520 is shown.

And current level 2630 may be set to one or more of one or more of 1) preventing the device 510 from breaking down, 2) preventing over current of the PA 750, and 3) maintaining the system reliability of the source device 510 Lt; / RTI >

In step 1420, the control and communication unit 710 may sense that the PA current has increased above the overcurrent level 2630. At this time, the control and communication unit 710 may control the source device 510 to prevent a breakdown of the source device 510, to prevent an overcurrent of the PA 750, The source device 510 (or PA 750) may be turned off for a period of time.

After a period of time, in steps 1420-1440, the control and communication 710 may communicate with one or more target devices 520 to verify the target device status of each of the target devices 520 (s) .

In step 1460, the control and communication unit 710 may control the wireless power transfer operation by controlling the PA power according to the target device states of the one or more target devices 520. [ At this time, if the controlled PA current is greater than or equal to the overcurrent level 2630, the control and communication unit 710 turns off the source device 510 (or the PA 750) Mode.

27 shows an electric vehicle charging system according to an embodiment.

27, an electric vehicle charging system 2700 includes a source system 2710, a source resonator 2720, a target resonator 2730, a target system 2740, and a battery 2750 for an electric vehicle.

The electric vehicle charging system 2700 has a structure similar to that of the wireless power transmission system of Fig. That is, the electric vehicle charging system 2700 includes a source composed of a source system 2710 and a source resonator 2720. The electric vehicle charging system 2700 also includes a target comprised of a target resonator 2730 and a target system 2740.

At this time, the source system 2710 may include an AC / DC converter, a power detector, a power conversion unit, a control unit, and a communication unit like the source device 110 of FIG. At this time, the target system 2740 may include a rectifier, a DC / DC converter, a switch, a charger, and a control and communication unit, as in the target device 120 of FIG.

The electric vehicle battery 2750 may be charged by the target system 2740.

The electric vehicle charging system 2700 can use a resonant frequency of several KHz to several tens MHz.

The source system 2710 may generate power according to the type of the charged vehicle, the capacity of the battery, and the state of charge of the battery, and may supply the generated power to the target system 2740.

The source system 2710 may perform control to align the alignment of the source resonator 2720 and the target resonator 2730. For example, the control of the source system 2710 may control the alignment by sending a message to the target system 2740 if the alignment of the source resonator 2720 and the target resonator 2730 is not aligned.

In this case, the case where the alignment is not correct may be a case where the position of the target resonator 2730 is not in a position for maximizing magnetic resonance. That is, if the vehicle is not correctly stopped, the source system 2710 can guide the alignment of the source resonator 2720 and the target resonator 2730 by guiding them to adjust the position of the vehicle.

The source system 2710 and the target system 2740 can communicate with each other through communication, send and receive an identifier of the vehicle, and exchange various messages.

The contents described in Figs. 2 to 26 can be applied to the electric vehicle charging system 2700. Fig. However, the electric vehicle charging system 2700 may use a resonance frequency of several KHz to several tens MHz, and may perform power transmission of several tens of watt or more in order to charge the electric vehicle battery 2750.

The method according to an embodiment of the present invention can be implemented in the form of a program command which can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

510: source device
520: Target device

Claims (21)

A control unit for determining a first output power for the target device in response to the target device being located within a power transfer area;
A power converter for outputting the first output power;
A transmitter for transmitting wireless power to the target device based on the first output power; And
A power detector for detecting a first current of the first output power;
Lt; / RTI >
Wherein the controller detects that the first current changes to a second current through the power detector, receives the status of the target device from the target device, and based on the change of the first current and the status of the target device To control the wireless power transmission operation by adjusting the first output power to a second output power based on the second current in accordance with the state of the wireless power transmission,
Wherein the controller adjusts the first output power to the second output power in response to a change time of the first current and a change degree of the first current exceeding a certain range,
Wireless power transmission device. delete delete delete delete The method according to claim 1,
And the control unit stops outputting the first output power when the second current corresponds to a load when the target device is removed. The method according to claim 1,
Wherein the first current corresponds to a load when the target device is in the constant current mode and the second current corresponds to a load when the target device is in the constant voltage mode, And controls the wireless power transmission operation by adjusting the first output power to the second output power corresponding to the constant voltage mode. The method according to claim 1,
The target devices are plural,
Wherein the controller receives the status of the target device for each of the plurality of target devices and determines a status of the wireless power transmission based on the change in the first current and the states of the plurality of target devices, Transmission device. 9. The method of claim 8,
When the first current is smaller than the second current,
Wherein the states of the plurality of target devices include a state in which a charging state of some or all of the plurality of target devices is changed from a constant current mode to a constant voltage CV mode, The status indicating that the devices have been removed, and a status indicating that one or more of the plurality of target devices are buffered. 10. The method of claim 9,
If the first current is greater than the second current,
Wherein the plurality of target devices include an added target device,
Wherein the control unit controls the wireless power transmission operation by increasing the first output power to the second output power such that wireless power corresponding to the second output power is transmitted to the added target device. Transmitting wireless power to the target device based on a first output power for the target device in response to the target device being located within the power transfer area;
Sensing that a first current of the first output power changes to a second current;
Receiving a status of the target device from the target device;
Determining a state of the wireless power transmission based on the change in the first current and the state of the target device; And
Controlling the wireless power transmission operation by adjusting the first output power to a second output power based on the second current in accordance with the determined state of the wireless power transmission
Lt; / RTI >
Wherein the first output power is adjusted to the second output power in correspondence with a change time of the first current and a degree of change of the first current exceeding a certain range,
Control method of wireless power transmission. delete delete delete delete 12. The method of claim 11,
Wherein controlling the wireless power transmission operation comprises:
Stopping the output of the first output power when the second current corresponds to a load when the target device is removed
/ RTI > of claim 1, further comprising: 12. The method of claim 11,
Wherein the first current corresponds to a load when the target device is in a constant current mode and the second current corresponds to a load when the target device is in a constant voltage mode,
Wherein controlling the wireless power transmission operation comprises:
Controlling the wireless power transmission operation by adjusting the first output power corresponding to the constant current mode to the second output power corresponding to the constant voltage mode
/ RTI > of claim 1, further comprising: 12. The method of claim 11,
The target devices are plural,
Wherein receiving the status of the target device is performed for each of the plurality of target devices,
Wherein determining the status of the wireless power transmission comprises:
Determining a state of the wireless power transmission based on a change in the first current and states of the plurality of target devices
/ RTI > of claim 1, further comprising: 19. The method of claim 18,
When the first current is smaller than the second current,
Wherein the states of the plurality of target devices include a state in which a charging state of some or all of the plurality of target devices is changed from a constant current mode to a constant voltage CV mode, The status indicating that the devices have been removed and the status indicating that one or more of the plurality of target devices are buffered. 19. The method of claim 18,
If the first current is greater than the second current,
Wherein the plurality of target devices include an added target device,
Wherein the step of controlling the wireless power transmission operation includes the step of increasing the first output power to the second output power such that the wireless power corresponding to the second output power is transmitted to the added target device
/ RTI > of claim 1, further comprising: A computer-readable recording medium embodying a program for performing a method of controlling a wireless power transmission according to any one of claims 11, 16 and 20.

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