Wireless power transmission and charging system, and power control method of wireless power transmission and charging system

A wireless power transmission and charging system, and a power control method of the wireless power transmission and charging system are provided. The power control method may include generating charging power using the power amplifier. The charging power may be used to charge a target device. The charging power may be transmitted to the target device. The voltage supplied to the power amplifier may be adjusted based on a detected change in the current input to the power amplifier, a detected change in the temperature of the source device, a detected change in the amount of the power received to the target device, or a detected change in the temperature of the target device.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit under 35 U.S.C. §119(a) of Korean Patent Application No. 10-2011-0051888, filed on May 31, 2011, in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference for all purposes.

BACKGROUND

The following description relates to wireless power transmission and charging.

2. Description of Related Art

Wireless power refers to energy that is transferred from a wireless power transmitter to a wireless power receiver, for example, through magnetic coupling. A typical wireless power transmission and charging system includes a source device and a target device. The source device may wirelessly transmit a power, and the target device may wirelessly receive a power. The source device includes a source resonator, and the target device includes a target resonator. Magnetic coupling or resonance coupling may be formed between the source resonator and the target resonator.

SUMMARY

According to an aspect, a power control method of a wireless power transmission and charging system may include: generating charging power using the power amplifier, the charging power being used to charge a target device; transmitting the charging power to the target device; detecting a change in a current input to the power amplifier, a change in a temperature of the source device, a change in an amount of a power received to the target device, or a change in a temperature of the target device; and adjusting a voltage supplied to the power amplifier, based on the detected change in the current input to the power amplifier, the detected change in the temperature of the source device, the detected change in the amount of the power received to the target device, or the detected change in the temperature of the target device.

The power control method may further include: assigning, by a source device, a control identifier (ID) to the at least one target device, the control ID being used to identify the target device.

The power control method may further include: determining an amount of a reference power, based on a battery state of the target device to which the control ID is assigned, the reference power being supplied to a power amplifier.

The adjusting may include: adjusting the voltage supplied to the power amplifier, so that the reference power is supplied to the power amplifier.

The adjusting may include: adjusting the voltage supplied to the power amplifier using a lookup table configured to store an amount of the voltage to be adjusted based on the change in the temperature of the source device.

The change in the temperature of the target device may be detected based on data received from the target device.

The change in the amount of the power received to the target device may be detected, based on data received from the target device, a pre-measured power transmission efficiency, and an output power amount of the power amplifier.

The assigning may include: transmitting an access standard instruction comprising an access standard required to identify a plurality of target devices; transmitting a call parameter to the plurality of target devices, to detect temporary IDs of the plurality of target devices, the temporary IDs being created based on the access standard; and assigning control IDs to the plurality of target devices, based on a plurality of response signals received from the plurality of target devices in response to the call parameter.

The access standard instruction may include: a reference point field, a call argument field, and a movement argument field, wherein the reference point field indicates a reference point that is used to create a temporary ID of a target device from a unique ID of the target device, and the call argument field indicates n consecutive bits starting from the reference point, and the movement argument field indicates a number of bits corresponding to a movement of the reference point.

The transmitting of the call parameter may include: transmitting the call parameter at predetermined intervals, the call parameter being generated based on a value set in the call argument field.

The assigning of the control IDs may include: assigning a control ID to a target device having a temporary ID identical to the call parameter, when the target device transmits an acknowledge (ACK) signal in response to the call parameter.

According to another aspect, a wireless power transmitter of a wireless power transmission and charging system may include: a power converter configured to generate power; a source resonator configured to transmit the power to a target device; and a control/communication unit configured to adjust a voltage supplied to a power amplifier based on a change in a current input to the power amplifier, wherein a change in a temperature of the source device, a change in an amount of a power received to the target device, or a change in a temperature of the target device.

The power converter may be configured to generate power by converting a direct current (DC) voltage to an alternating current (AC) voltage using a resonance frequency.

The control/communication unit may be further configured to: assign a control identifier (ID) to the target device, and determine an amount of a reference power based on a battery state of the target device to which the control ID is assigned, wherein the control ID is to identify the target device, and the reference power is supplied to the power amplifier.

According to a further aspect, a power receiving method of a wireless power transmission and charging system may include: receiving a charging power for the charging operation from the source device; transmitting, to the source device, information on an amount of a received power, or information on a change in a temperature of a target device, based on a request of the source device; and receiving the charging power from the source device, after the source device adjusts a voltage supplied to a power amplifier of the source device based on the information on the amount of the received power or the information on the change in the temperature of the target device.

The power receiving method may further include: receiving a wake-up power and a wake-up request message from the source device; and transmitting, to the source device, an acknowledge (ACK) message in response to the wake-up request message.

The power receiving method may further include: receiving, from the source device, an assigned control identifier (ID), the control ID being used in a charging operation.

The receiving of the assigned control ID may include: receiving an access standard instruction comprising an access standard required to identify a plurality of target devices; creating a temporary ID of a target device based on a value set in a reference point field, a value set in a call argument field, and a value set in a movement argument field, the reference point field, the call argument field, and the movement argument field being included in the access standard instruction; receiving a call parameter generated based on the value set in the call argument field; comparing the temporary ID with the call parameter; transmitting, to the source device, a response signal in response to the call parameter, when the temporary ID is identical to the call parameter; and receiving the assigned control ID from the source device.

The power receiving method may further include: receiving an access standard instruction from the source device, when the source device determines, based on a plurality of response signals, that a plurality of target devices have identical temporary IDs, the access standard instruction being updated by changing the value set in the movement argument field; and updating the temporary IDs of the target devices based on the received access standard instruction.

DETAILED DESCRIPTION

FIG. 1illustrates a wireless power transmission and charging system.

As shown, the wireless power transmission and charging system includes a source device110, and a target device120.

The source device110may include an alternating current-to-direct current (AC/DC) converter111, a power detector113, a power converter114, a control/communication unit115, and a source resonator116.

The target device120may include a target resonator121, a rectification unit122, a DC-to-DC (DC/DC) converter123, a switch unit124, a charging unit125, and a control/communication unit126.

The AC/DC converter111may be configured to generate DC voltage by rectifying AC voltage (e.g., in a band of tens of hertz (Hz)) output from a power supply112. The AC/DC converter111may output DC voltage of a predetermined level, may adjust an output level of the DC voltage based on the control of the control/communication unit115, or both.

The power detector113may be configured to detect an output current and an output voltage of the AC/DC converter111, and may transfer, to the control/communication unit115, information on the detected current and the detected voltage. Additionally, the power detector113may detect an input current and an input voltage of the power converter114.

The power converter114may be configured to generate power by converting DC voltage of a predetermined level to AC voltage, for instance, using a switching pulse signal in a band of a few megahertz (MHz) to tens of MHz. In some embodiments, the power converter114may convert DC voltage supplied to a power amplifier to AC voltage, using a reference resonance frequency FRef, and may generate a power.

In some embodiments, the impedance adjusting unit may be included which include N matching switches connected to a plurality of capacitors. The impedance adjusting unit may adjust an impedance of the source resonator116by turning ON or OFF the N matching switches. The impedance adjusting unit may include a Pi matching circuit or a T matching circuit.

The control/communication unit115may be configured to detect a reflected wave of a transmission power, and may detect mismatching between the target resonator121and the source resonator116based on the detected reflected wave. To detect the mismatching, the control/communication unit115may detect an envelope of the reflected wave, detect a power amount of the reflected wave, or both.

For example, the control/communication unit115may be configured to compute a voltage standing wave ratio (VSWR), based on a voltage level of the reflected wave, and based on a level of an output voltage of the source resonator116or the power converter114. For example, when the VSWR is less than a predetermined value, the control/communication unit115may be configured to determine that the mismatching is detected. In this example, the control/communication unit115may turn ON or OFF the N matching switches, may determine a tracking impedance ImBestwith the best power transmission efficiency, and may adjust the impedance of the source resonator116to the tracking impedance ImBest.

Additionally, the control/communication unit115may adjust a frequency of a switching pulse signal. Under the control of the control/communication unit115, the frequency of the switching pulse signal may be determined. By controlling the power converter114, the control/communication unit115may generate a modulation signal to be transmitted to the target device120. The control/communication unit115may transmit various messages to the target device120via in-band communication. Additionally, the control/communication unit115may detect a reflected wave, and may demodulate a signal received from the target device120through an envelope of the detected reflected wave.

The control/communication unit115may generate a modulation signal for in-band communication, using various schemes. To generate a modulation signal, the control/communication unit115may turn ON or OFF a switching pulse signal, or may perform delta-sigma modulation. Additionally, the control/communication unit115may generate a pulse-width modulation (PWM) signal with a predetermined envelope.

The control/communication unit115may perform out-band communication using a communication channel. The control/communication unit115may include a communication module, such as one configured to process ZigBee, Bluetooth, Wi-Fi, Wi-Max, near field communication (NFC), radio frequency identification (RFID), and/or the like communications. The control/communication unit115may transmit or receive data to or from the target device120via the out-band communication.

The source resonator116may transfer an electromagnetic energy to the target resonator121. In one or more embodiments, the source resonator116may transfer, to the target device120, communication power used for communication or charging power used for charging, for instance, via a magnetic coupling with the target resonator121.

The target resonator121may receive the electromagnetic energy from the source resonator116. For example, the target resonator121may receive, from the source device110, the communication power or charging power via the magnetic coupling with the source resonator116. Additionally, the target resonator121may receive various messages from the source device110via the in-band communication.

The rectification unit122may generate a DC voltage by rectifying an AC voltage. Here, the AC voltage may be received from the target resonator121.

The DC/DC converter123may adjust a level of the DC voltage output from the rectification unit122, based on a capacity of the charging unit125. For example, the DC/DC converter123may adjust, to 3 to 10 V, the level of the DC voltage output from the rectification unit122.

The switch unit124may be turned ON or OFF, under the control of the control/communication unit126. When the switch unit124is turned OFF, the control/communication unit115of the source device110may detect a reflected wave. In other words, when the switch unit124is turned OFF, the magnetic coupling between the source resonator116and the target resonator121may be eliminated.

The charging unit125may include at least one battery. The charging unit125may charge the battery using a DC voltage output from the DC/DC converter123.

The control/communication unit126may perform in-band communication for transmitting or receiving data using a resonance frequency. During the in-band communication, the control/communication unit126may demodulate a received signal by detecting a signal between the target resonator121and the rectification unit122, or detecting an output signal of the rectification unit122. The control/communication unit126may demodulate a message received via the in-band communication.

Additionally, the control/communication unit126may adjust an impedance of the target resonator121, to modulate a signal to be transmitted to the source device110. The control/communication unit126may modulate the signal to be transmitted to the source device110, by turning ON or OFF the switch unit124. For example, the control/communication unit126may increase the impedance of the target resonator121, so that a reflected wave may be detected from the control/communication unit115of the source device110. Depending on whether the reflected wave is detected, the control/communication unit115may detect a binary number (e.g., “0” or “1.”).

The control/communication unit126may transmit a response message to a wireless power transmitter. The response message may include, for example, a “type of a corresponding target device,” “information on a manufacturer of a corresponding target device,” “a model name of a corresponding target device,” a “battery type of a corresponding target device,” a “scheme of charging a corresponding target device,” an “impedance value of a load of a corresponding target device,” “information on characteristics of a target resonator of a corresponding target device,” “information on a frequency band used by a corresponding target device,” an “amount of a power consumed by a corresponding target device,” an “identifier (ID) of a corresponding target device,” or “information on version or standard of a corresponding target device.”

The control/communication unit126may also perform out-band communication using a communication channel. The control/communication unit126may include a communication module, such as one configured to process ZigBee, Bluetooth, Wi-Fi, Wi-Max and/or the like communications. The control/communication unit126may transmit or receive data to or from the source device110via the out-band communication, for instance.

The control/communication unit126may be configured to receive a wake-up request message from the wireless power transmitter, may detect an amount of a power received to the target resonator121, and may transmit, to the wireless power transmitter, information on the detected amount of the power. The information on the detected amount may include, for example, an input voltage value and an input current value of the rectification unit122, an output voltage value and an output current value of the rectification unit122, an output voltage value and an output current value of the DC/DC converter123, and the like.

The term “in-band” communication(s), as used herein, means communication(s) in which information (such as, for example, control information, data and/or metadata) is transmitted in the same frequency band, and/or on the same channel, as used for power transmission. According to one or more embodiments, the frequency may be a resonance frequency. And, the term “out-band” communication(s), as used herein, means communication(s) in which information (such as, for example, control information, data and/or metadata) is transmitted in a separate frequency band and/or using a separate or dedicated channel, than used for power transmission.

FIG. 2further illustrates one configuration of the wireless power transmitter.

Referring toFIG. 2, the wireless power transmitter may further include a temperature sensor230. The temperature sensor230may be configured to measure and/or sense a temperature of a surrounding area of the power converter114, or a temperature inside the wireless power transmitter, and may transfer data regarding the sensed temperature to the control/communication unit115. For example, the temperature sensor230may include a thermometer or thermocouple. As illustrated inFIG. 2, the power converter114includes a switching pulse signal generator210, and a power amplifier220.

The switching pulse signal generator210may generate a switching pulse signal in a band of a few MHz to tens of MHz, for instance. The frequency of the generated switching pulse signal may be determined, under the control of the control/communication unit115. For example, when a reference resonance frequency FRefof the source resonator116is set to 13.56 MHz or 5.78 MHz, the control/communication unit115may control the switching pulse signal generator210, so that the frequency of the switching pulse signal may be set to 13.56 MHz or 5.78 MHz. The switching pulse signal generator210may include a plurality of capacitors, and a switch, for example. The switching pulse signal generator210may adjust the frequency of the switching pulse signal by switching the plurality of capacitors.

The power amplifier220may generate an AC power by a switching pulse signal output from the switching pulse signal generator210. For instance, the power amplifier220may generate a communication power for communication, or a charging power for charging, by adjusting an input voltage of the power amplifier220ofFIG. 2based on the switching pulse signal. The power converter114may generate, using the power amplifier220, a charging power used to charge a target device to which a control identifier (ID) is assigned. The communication power may be, for example, a wake-up power.

The control/communication unit115may determine an amount of a reference power supplied to the power amplifier220, based on a battery state of the target device to which the control ID is assigned. The wireless power transmitter may determine a battery state and battery specification of a target device, and an amount of a power required to charge the battery, through an operation of assigning a control ID as illustrated inFIG. 3. The amount of the reference power may be determined based on the battery state, the battery specification, and the amount of the power required to charge the battery.

The control/communication unit115may adjust a signal level of the input voltage of the power amplifier220, based on a number of target devices. Additionally, the control/communication unit115may adjust the reference resonance frequency FRef, based on a reflected wave of the charging power, an amount of a power received to each of the target devices, an amount of the charging power, and/or a transmission efficiency of the charging power.

The control/communication unit115may detect a change in a current input to the power amplifier220, a change in a temperature of the source device110, a change in an amount of a power received to the target device120, or a change in a temperature of the target device120. The power detector113may detect an amount of a power supplied to the power amplifier220, and may report the detected amount of the power to the control/communication unit115.

The control/communication unit115may adjust the voltage supplied to the power amplifier220, based on the change in the current input to the power amplifier220, the change in the temperature of the source device110, the change in the amount of the power received to the target device120, or the change in the temperature of the target device120. In some embodiments, the control/communication unit115may adjust the voltage supplied to the power amplifier220, so that a reference power of a predetermined level may be supplied to the power amplifier220. For example, when a charging state of the target device120is changed, or when the temperature of the source device110is changed, the current input to the power amplifier220may be changed, and thus an output current value of the power amplifier220may be changed. Accordingly, the control/communication unit115may detect an environmental change, and may adjust the voltage supplied to the power amplifier220, so that a reference power of a predetermined level may be supplied to the power amplifier220despite the environmental change.

The control/communication unit115may adjust the voltage supplied to the power amplifier220, using a lookup table. The lookup table may be configured to store an amount of the voltage to be adjusted based on the change in the temperature of the source device110. For example, the lookup table may include, for example, data obtained by mapping an amount of the adjusted input voltage of the power amplifier220to an amount of the change in the temperature of the source device110.

The change in the temperature of the target device120may be detected based on data received from the target device120. The source device110may continue to transmit the charging power for a predetermined period of time, and may then send a request for temperature information to the target device120. In response to the request for the temperature information, the target device120may transmit, to the source device110, data regarding the temperature of the target device120. Similarly, the change in the amount of the power received to the target device120may be detected, based on data received from the target device120, a pre-measured power transmission efficiency, and an output power amount of the power amplifier220. Prior to transmitting the charging power, the power transmission efficiency may be measured. For example, when the amount of the power received to the target device120is less than a value obtained by multiplying the power transmission efficiency and the output power amount of the power amplifier220, the control/communication unit115may increase the input voltage of the power amplifier220. The temperature information, and the amount of the received power may be requested at regular intervals.

FIG. 3illustrates an example of a power control method of a wireless power transmission and charging system.

As used herein, the term “source” is used to simply refer to a source device, and the term “target” is used to simply refer to a target device. A source device may be used to supply a wireless power, and may include all electronic devices enabling power supply, for example, a pad, a terminal, a TV, and/or the like. A target device may be used to receive a supplied wireless power, and may include all electronic devices requiring a power.

Referring toFIG. 3, in operation310, the source, namely a wireless power transmitter, is switched from a standby mode to a detection mode, by a charging start button or a detection by a sensor. In the standby mode, the source may not perform any operation. In the detection mode, operations310and315may be performed.

In operation315, the source determines a number of target devices. Next, in operation320, the source may transmit a wake-up power and a wake-up request signal, may receive at least one acknowledge (ACK) message with respect to the wake-up request signal, and may determine the number of target devices based on a number of received ACK messages. The wake-up power may be a power required by a target device to perform a basic communication between the target device and the source. In other words, the target devices may receive the wake-up power and the wake-up request signal from the source, and may transmit response signals in response to the wake-up request signal.

In a situation when the source is switched from the standby mode to the detection mode by the sensor, and at least one ACK message in response to the wake-up request signal is not received from at least one target device within a predetermined period of time, the source may be switched from the detection mode to the standby mode. Accordingly, when an object other than the target device is placed on a pad unit, the source may be activated for a while only, and then may enter the standby mode again.

In operation360, a control ID used in a charging operation may be assigned to a target device. When a plurality of target devices exist, control IDs may be used to identify the plurality of target devices. Thus, at least one control ID may be used to identify at least one target device during the charging operation.

When operation360is completed, the source may transmit a charging power to the target device to which the control ID is assigned, for instance, via a magnetic coupling. The charging power may be used to charge the target device with the control ID. When operation360is completed, the source may determine an amount of a reference power supplied to a power amplifier based on a battery state of the target device with the control ID. The battery state of the target device may include a charging state or a discharging state of a battery of the target device. For example, when the battery of the target device is completely discharged, the amount of the reference power may be determined based on a power transmission efficiency and/or a power required to charge the battery.

In some instances, a plurality of target devices may be simultaneously placed on the pad unit, and may be simultaneously charged. Accordingly, there may be provided a method for identifying the plurality of target devices. Operation360may be performed to avoid communication collision.

In operation320, the source transmits an access standard instruction to a plurality of target devices that are detected by the source. When a predetermined period of time elapses after the wake-up power is transmitted to the detected target devices, the source may transmit the access standard instruction to the detected target devices.

The access standard instruction may include a reference point field, a call argument field, and a movement argument field. A value set in the reference point field may indicate a reference point used to create a temporary ID of a target device from a unique ID of the target device. In a situation where a reference point is set in advance between a source and a target device, the reference point field may be omitted from the access standard instruction. On the other hand, when either a most significant bit (MSB) or a least significant bit (LSB) among bits of a unique ID of a target device is set as a reference point, in advance between a source and the target device, the reference point field may also be omitted from the access standard instruction.

Additionally, a value set in the call argument field may indicate n consecutive bits starting from the reference point. A value set in the movement argument field may indicate a number of bits corresponding to movement of the reference point.

Target devices may create their respective temporary IDs using a portion of their own IDs based on an access standard.

In operation330, the source determines whether a plurality of response signals are received from the detected target devices. For example, when a temporary ID of a target device is identical to the call parameter, the target device may transmit, to the source, a response signal. The response signal may be an ACK signal. When a response signal is received, the source may acquire information on a temporary ID of a target device.

When no response signal is received from the detected target devices, the source determines whether the call parameter transmitted in operation325is a last call parameter in operation335. When the call parameter transmitted in operation325is determined to be the last call parameter, the source may terminate the power control method ofFIG. 3. For example, when a call argument is set to “3,” the source may transmit call parameters having values of “000” to “111.” The call parameter “111” may correspond to the last call parameter. Additionally, when the call parameter transmitted in operation325is determined to be the last call parameter, the source may determine the detected target devices as targets that do not require charging, or as targets that are not compatible with the source.

When the response signals are received from the target devices, the source determines whether temporary IDs of the target devices overlap based on the response signals in operation345. For example, when a plurality of response signals are received in response to a call parameter within a predetermined period of time, the source may determine that the temporary IDs of the target devices overlap.

When it is determined that the temporary IDs do not overlap, the source assigns control IDs to target devices that transmit the response signals, in operation350. A control ID may be assigned to a target device, so that the source may independently control the target device to which the control ID is assigned. For example, the source may individually transmit a power to the target device with the control ID, and may transmit or receive required data to or from the target device with the control ID. Subsequently, the source may transmit the call parameter to target devices other than the target device with the control ID in the same manner as operation325, until control IDs are respectively assigned to all of the detected target devices. A currently transmitted call parameter may be updated from a previously transmitted call parameter.

When it is determined that the temporary IDs overlap, that is, are identical, the source transmits an updated access standard instruction to the target devices with the identical temporary IDs in operation355. The source may update the access standard instruction by changing at least one of the reference point, the call argument, and the movement argument. The target devices with the identical temporary IDs may update their temporary IDs based on the updated access standard instruction.

Subsequently, the source may transmit the call parameter to the target devices with the identical temporary IDs in the same manner as operation325. The source may repeat operations310to325until control IDs are respectively assigned to all of the detected target devices, as needed.

As described above, with reference toFIGS. 2 and 3, to control a power in the wireless power transmission and charging system, a control ID used to identify at least one target device during a charging operation may be assigned by the source device110to the target device. Additionally, an amount of a reference power supplied to the power amplifier220, based on a battery state of the target device to which the control ID is assigned. Furthermore, a charging power used to charge the target device to which the control ID is assigned may be generated using the power amplifier220, and may be transmitted to the target device via a magnetic coupling. Moreover, a change in a current input to the power amplifier220, a change in a temperature of the source device110, a change in an amount of a power received to the target device, or a change in a temperature of the target device may be detected.

The power control method of the wireless power transmission and charging system may be performed by a target device. When a source device is switched from the standby mode to the detection mode, the target device may receive, from the source device, a wake-up power and a wake-up request message. Additionally, the target device may transmit, to the source device, an ACK message in response to the wake-up request message. The target device may receive a control ID that is assigned by the source device and that is to be used in a charging operation. Furthermore, the target device may receive a charging power for the charging operation from the source device via a magnetic coupling. In response to a request of the source device, the target device may transmit, to the source device, information on an amount of a received power, or information on a change in a temperature of the target device. Moreover, the target device may receive the charging power from the source device, after the source device adjusts a voltage supplied to a power amplifier of the source device based on the information on the amount of the received power or the information on the change in the temperature of the target device.

It may be possible to increase power transmission efficiency by controlling a power supplied to a target device. Additionally, it may be possible to efficiently identify a target device by using, as a temporary ID of the target device, a portion of a unique ID of the target device that contains characteristics of the target device.

Furthermore, a source device may independently transmit a wireless power and data to a target device by assigning a control ID to the target device.

FIGS. 4A and 4Billustrate a basic format of an access standard instruction.

Specifically,FIG. 4Aillustrates fields included in an access standard instruction. The access standard instruction may include, for example, a start bit (SB) field401, a target ID (T_ID) field403, a command (CMD) field405, a reference point field407, a call argument field409, a movement argument field411, and a check bit (CB) field413. A target device may receive an access standard through the access standard instruction, and may generate information used to identify target devices.

The SB field401may include a bit-type identifier indicating the beginning of a packet. For example, N bits may be assigned to the SB field401based on a size of the entire packet.

When a control ID is assigned to a target device, the T_ID field403may include the control ID. On the other hand, when a control ID is not assigned to a target device, the T_ID field403may include a null value.

The CMD field405may include an instruction used to define an operation of a source. The instruction may include, for example, a reset instruction, an instruction to request an input voltage and input current of a target device, an instruction to request an output voltage and output current of a DC-to-DC converter of a target device, an ACK instruction, an instruction to request a load of a target device to be powered on, an instruction to request a load of a target device to be powered OFF, an instruction to request state information of a target device, an instruction to transfer an access standard, a negative acknowledge (NACK) instruction, an instruction to assign a control ID, an instruction to request registration information of a target device, and/or the like. Additionally, a code may be assigned to each instruction. SinceFIG. 4Aillustrates the access standard instruction, the CMD field405may include the access standard instruction. Various bits may be assigned to the CMD field405based on a number of instructions.

The reference point field407may include a reference point. The reference point may refer to a reference used to create a temporary ID of a target device from a unique ID of the target device. The reference point may be, for example, an MSB or an LSB among bits of the unique ID of the target device. Additionally, the reference point may represent a predetermined position of the unique ID of the target device. When a reference point is set in advance between a source and a target device, the reference point field407may be omitted from the access standard instruction. And when an MSB or an LSB among bits of a unique ID of a target device is set as a reference point in advance, the reference point field407may also be omitted from the access standard instruction. As illustrated inFIG. 4A, the reference point field407is denoted by a dotted line box, because the reference point field407may be omitted from the access standard instruction.

The call argument field409may include a call argument. The call argument may indicate n consecutive bits starting from the reference point. A call parameter may be a value used when a source calls predetermined bits from a target device. The call parameter may be determined based on the call argument. For example, when the call argument is set to “3,” the call parameter may have a value from “000” to “111.”

The movement argument field411may include a movement argument. The movement argument may indicate a number of bits corresponding to movement of the reference point, and thus may indicate how much the reference point moves. For example, when a movement argument is set to “1,” a reference point may move to the right or the left by 1 bit. A number of bits assigned to the movement argument field411may be adjusted based on the size of the entire packet.

The CB field413may include a check bit used to verify accurate transmission of a packet.

Additionally, the access standard instruction may include various fields, in addition to the reference point field407, the call argument field409, and the movement argument field411. For example, the access standard instruction may include various fields assigned in bits or bytes.

FIG. 4Billustrates, in detail, the reference point field407, the call argument field409, and the movement argument field411. The reference point may be set in the reference point field407. When a reference point is set to an MSB, “M” or “1” may be set in a reference point field, as illustrated inFIG. 4B. And when a reference point is set to an LSB, “L” or “0” may be set in the reference point field, as illustrated inFIG. 4B. Additionally, the call argument may be set in the call argument field409. The call argument may be determined based on a number of detected target devices, and may have a value of “1” to “n,” as illustrated inFIG. 4B. The movement argument may be set in the movement argument field411. The movement argument may be determined based on the number of the detected target devices similarly to the call argument, and may have a value of “0” to “n,” as illustrated inFIG. 4B.

FIG. 5illustrates a basic format of an ID assignment instruction.

Referring toFIG. 5, the ID assignment instruction includes an SB field510, a control ID (T_No) field520, a CMD field530, and a CB field540. It may be configured as a communication packet.

The SB field510may include a bit-type identifier indicating the beginning of a packet. For example, N bits may be assigned to the SB field510based on a size of the entire packet.

The T_No field520may include a control ID assigned by a source to a target device. Based on the control ID of the T_No field520, the target device may acquire an ID that may be communicated independently of the source.

The CMD field530may include an instruction used to define an operation of a source. SinceFIG. 5illustrates the ID assignment instruction, the CMD field530may include the ID assignment instruction. A code may be assigned to an instruction.

The CB field540may include a check bit used to verify accurate transmission of a packet.

Additionally, the ID assignment instruction may include various fields, in addition to the SB field510, the T_No520, the CMD field530, and the CB field540. For example, the ID assignment instruction may include various fields assigned in bits or bytes.

FIG. 6illustrates a basic format of a response instruction of a target device.

Referring toFIG. 6, the response instruction includes a preamble (PA) field610, a start code (SC) field620, a CMD field630, and a cyclic redundancy checking (CRC)-5 field640. It may be configured as a communication packet. The PA field610may include dummy data that is optionally transmitted to prevent a loss of a wireless packet.

The SC field620may include an identifier indicating the beginning of a shortened packet, when a response instruction includes four fields, for example, the PA field610, the SC field620, the CMD field630, and the CRC-5 field640. In a packet, an address field of a transmitter, an address field of a receiver, a data field, and/or the like may be further included in a response instruction.

The CMD field630may include an instruction used to define an operation of a target device. The instruction may include, for example, a reset instruction, an instruction to respond to an input voltage and input current of a target device, an instruction to respond to an output voltage and output current of a DC-to-DC converter of a target device, an ACK instruction, an instruction to respond to state information of a target device, an instruction to respond to registration information of a target device, and the like. Additionally, a code may be assigned to each instruction. SinceFIG. 6illustrates the response instruction, the CMD field630may include the response instruction.

The CRC-5 field640may include a CRC code used to verify accurate transmission of a packet.

FIG. 7illustrates an operation of a source and an operation of a target device, based on a time slot, to explain avoidance of communication collision between two target devices. The source may be configured to simultaneously detect the two target devices. The two target devices may be, for example, a first target device and a second target device.

Referring toFIG. 7, in a period710, the source may transmit a wake-up power to the first target device and the second target device. The wake-up power may be used to operate controllers of the first target device and the second target device. In response to the wake-up power, the controllers may be operated, so that requirements for transmitting or receiving data to or from the source may be satisfied.

The amount of the wake-up power may be determined based on a maximum number of targets that is included in a system information area of a source illustrated inFIG. 15.

In a period720, the source may transmit an access standard instruction to the first target device and the second target device. In response to the access standard instruction, the first target device and the second target device may create their respective temporary IDs based on an access standard. To create each of the temporary IDs, a portion of each of unique IDs of the first target device and the second target device may be used. For example, each of the unique IDs of the first target device and the second target device may be included in a serial number area or a short ID area as illustrated inFIG. 16.

In a period730, the source may transmit a call parameter to the first target device and the second target device. The call parameter may be determined based on a call argument included in the access standard instruction. For example, when the call argument is set to “3,” the call parameter may have a value from “000” to “111.”

In a period740, the first target device may transmit, to the source, a response signal in response to the call parameter. When the temporary ID of the first target device is identical to the call parameter, the first target device may transmit the response signal.

In a period750, the source may assign a control ID to the first target device. The control ID may be set to “1.” The first target device with the control ID may transmit, to the source, an ACK signal stating that the assigned control ID is received.

In a period760, the source may continue to transmit another call argument to the first target device and the second target device. The source may continue to transmit, to the first target device and the second target device, another call parameter subsequent to the call parameter transmitted in the period730.

In a period770, the second target device may transmit, to the source, a response signal in response to the call parameter transmitted in the period760.

In a period780, the source may assign a control ID to the second target device. The control ID may be set to “2.” The second target device with the control ID may transmit, to the source, an ACK signal stating that the assigned control ID is received.

In a period790, the source may individually transmit a control instruction to the first target device and the second target device to which the control IDs are respectively assigned. The control instruction may include, for example, a charging instruction, a reset instruction, an instruction to check an operation status of a target device, an instruction to request temperature information of a target device, an instruction to request registration information of a target device, and/or the like.

In a time slot791, the source may transmit a first control instruction to control the first target device. In a time slot793, the first target device may transmit a response signal in response to the first control instruction. In a time slot795, the source may transmit a second control instruction to control the second target device. In a time slot797, the second target device may transmit a response signal in response to the second control instruction.

FIG. 8illustrates an operation of a source and an operation of a target device, based on a time slot, to explain avoidance of communication collision between three target devices. The source may be configured to simultaneously detect the three target devices. The three target devices may be, for example a first target device, a second target device, and a third target device.

Referring toFIG. 8, in a period801, the source may transmit a wake-up power to the first target device to the third target device. The wake-up power may be used to operate controllers of the first target device to the third target device. In response to the wake-up power, the controllers may be operated, so that requirements for transmitting or receiving data to or from the source may be satisfied.

In a period803, the source may transmit an access standard instruction to the first target device to the third target device. In response to the access standard instruction, the first target device to the third target device may create their respective temporary IDs based on an access standard. To create each of the temporary IDs, a portion of each of unique IDs of the first target device to the third target device may be used. For example, each of the unique IDs of the first target device to the third second target device may be included in a serial number area or a short ID area as illustrated inFIG. 16.

In a period805, the source may transmit a first call parameter to the first target device to the third target device. The first call parameter may be determined based on a call argument included in the access standard instruction. For example, when the call argument is set to “2,” the call parameter may have a value from “00” to “11.”

In a period807, the first target device and the second target device may transmit, to the source, two response signals in response to the first call parameter. When the temporary ID of the first target device, and the temporary ID of the second target device are identical to the first call parameter, the first target device and the second target device may transmit the two response signals. Since the two response signals are received, the source may determine that the first target device and the second target device collide.

In a period809, the source may continue to transmit a second call parameter to the first target device to the third target device. For instance, the source may continue to transmit, to the first target device to the third target device, the second call parameter subsequent to the first call parameter transmitted in the period805.

In a period811, the third target device may transmit, to the source, a response signal in response to the second call parameter transmitted by the source in the period809. When the temporary ID of the third target device is identical to the second call parameter, the third target device may transmit the response signal. Conversely, when the temporary ID of the third target device is different from the second call parameter, the third target device may not transmit a response signal.

In a period813, the source may assign a control ID to the third target device. The control ID may be set to “1.” The third target device with the control ID may transmit, to the source, an ACK signal stating that the assigned control ID is received.

In a period815, the source may transmit another access standard instruction to the first target device and the second target device that collide. The access standard instruction may include a movement argument field. The source may change a value set in the movement argument field, to identify the first target device and the second target device, so that a new access standard may be agreed between the source and the first target device and the second target device. Additionally, the source may generate a new access standard instruction by changing a value set in a reference point field, or a value set in a call argument field. The first target device and the second target device may receive the new access standard instruction, and may update their respective temporary IDs based on the new access standard.

In a period817, the source may transmit a third call parameter to the first target device and the second target device. The third call parameter may be determined based on a call argument included in the access standard instruction. Additionally, the call argument may be determined based on a number of target devices detected by the source. For example, when three target devices are detected, the call argument may be set to a value equal to or greater than 2, to identify the three target devices.

In a period819, the first target device may transmit, to the source, a response signal in response to the third call parameter transmitted by the source in the period817. When the updated temporary ID of the first target device is identical to the third call parameter, the first target device may transmit the response signal.

In a period821, the source may assign a control ID to the first target device. The control ID may be set to “2.” The first target device with the control ID may transmit, to the source, an ACK signal stating that the assigned control ID is received.

In a period823, the source may continue to transmit a fourth call parameter to the first target device and the second target device. The source may continue to transmit, to the first target device and the second target device, the fourth call parameter subsequent to the third call parameter transmitted in the period817.

In a period825, the second target device may transmit, to the source, a response signal in response to the fourth call parameter transmitted by the source in the period823. When the updated temporary ID of the second target device is identical to the fourth call parameter, the second target device may transmit the response signal.

In a period827, the source may assign a control ID to the second target device. The control ID may be set to “3.” The second target device with the control ID may transmit, to the source, an ACK signal stating that the assigned control ID is received.

In a period830, the source may individually transmit a control instruction to the first target device to the third target device to which the control IDs are respectively assigned. The control instruction may include, for example, a charging instruction, a reset instruction, an instruction to check an operation status of a target device, an instruction to request temperature information of a target device, an instruction to request registration information of a target device, and/or the like.

Specifically, in a time slot831, the source may transmit a first control instruction to control the third target device. In a time slot833, the third target device may transmit a response signal in response to the first control instruction. In a time slot835, the source may transmit a second control instruction to control the second target device. In a time slot837, the second target device may transmit a response signal in response to the second control instruction.

FIG. 9illustrates a reference point in an operation of identifying target devices to avoid communication collision.

A source may transmit an access standard instruction to a plurality of target devices. The access standard instruction may include a reference point field. A value set in the reference point field may indicate a reference point, and the reference point may refer to a reference used to create a temporary ID of a target device from a unique ID of the target device. The reference point may include, for example, an MSB or an LSB among bits of the unique ID of the target device. For example, the unique ID of the target device may be included in a serial number area or a short ID area as illustrated inFIG. 16.

As illustrated inFIG. 9, an MSB910, or an LSB920may be set as a reference point of a first target. For example, an access standard instruction may be transmitted to n targets and accordingly, the reference point may equally be applied to the n targets. In a situation where the reference point of the first target is set to the MSB910, a reference point of a second target may also be set to the MSB910, not the LSB920.

FIG. 10illustrates a call argument and a call parameter in an operation of identifying target devices to avoid communication collision.

A source may transmit an access standard instruction to a plurality of target devices. The access standard instruction may include a call argument field. A value set in the call argument field may indicate a call argument, and the call argument may refer to n consecutive bits starting from a reference point. The call argument may be determined based on a number of target devices detected by the source. For example, when five target devices are detected, a call argument may be set to a value equal to or greater than 3, because eight cases represented by 3 bits may be identified. Additionally, a call parameter may be used to call a predetermined bit from a target device. The call parameter may be determined based on the call argument. For example, when the call argument is set to “3,” the call parameter may have a value from “000” to “111”.

As illustrated inFIG. 10, a call argument may be set to “3.” Accordingly, the source may call three consecutive bits starting from a reference point. The source may call three consecutive bits, rightward starting from an MSB of a unique ID of a target device. In another example, the source may call three consecutive bits, leftward starting from an LSB of the unique ID of the target device. For example, the unique ID of the target device may be included in a serial number area or a short ID area as illustrated inFIG. 16.

Referring toFIG. 10, when the MSB is set as a reference point, the source may call three bits “110”1010from a first target. Additionally, when the LSB is set as a reference point, the source may call three bits “001”1020from the first target. Since the access standard instruction may equally be applied to n targets, the call argument may need to be equally applied to the n targets.

FIG. 11illustrates a movement argument in an operation of identifying target devices to avoid communication collision.

A source may transmit an access standard instruction to a plurality of target devices. The access standard instruction may include a movement argument field. A value set in the movement argument field may indicate a movement argument, and the movement argument may refer to a number of bits corresponding to movement of the reference point. The movement argument may indicate how much the reference point moves. For example, when the movement argument is set to “1,” the reference point may move to the right or the left by 1 bit.

Referring toFIG. 11, the movement argument may be set to “1.” Accordingly, a reference point may move to the right or the left by 1 bit. In a situation in which an MSB is set as a reference point, the reference point may move to the right by 1 bit, based on the movement argument. The source may call three bits “100”1110from a first target. On the other hand, when an LSB is set as a reference point, the reference point may move to the left by 1 bit, based on the movement argument. For example, the source may call three bits “000”1120from the first target. Since the access standard instruction may equally be applied to n targets, the call argument may need to be equally applied to the n targets.

FIG. 12illustrates a situation where temporary IDs of target devices overlap.

A target device may receive an access standard instruction from a source. The target device may create its temporary ID based on an access standard. The access standard may include a reference point, a call argument, and a movement argument.

Referring toFIG. 12, a reference point, a call argument, and a movement argument are set to an MSB, “3,” and “0,” respectively. Target devices may create their own temporary IDs, based on the reference point, the call argument, and the movement argument. A temporary ID of a first target may be set to “110”1210, and a temporary ID of a second target may be set to “101”1220. Additionally, a temporary ID of a third target may be set to “111”1230, and a temporary ID of a fourth target may be set to “111”1240. Furthermore, a temporary ID of an n-th target may be set to “011”1250. The temporary ID of the third target may be identical to the temporary ID of the fourth target, that is, the temporary IDs may overlap.

The source may sequentially transmit call parameters having values of “000” to “111.” Additionally, the source may sequentially transmit call parameters having values of “111” to “000.” As illustrated inFIG. 12, the source may sequentially transmit call parameters having values of “000” to “111.” When temporary IDs of target devices are identical to a call parameter, the target devices may transmit response signals to the source. When the response signals are received, the source may determine whether the received response signals overlap. And, if the response signals do not overlap, the source may assign control IDs to the target devices that transmit the response signals, respectively.

As illustrated inFIG. 12, the temporary ID of the n-th target is less than the temporary IDs of the other targets has the smallest value and accordingly, the source may assign a control ID “1” to the n-th target. The temporary ID of the second target has a second smallest value and accordingly, the source may assign a control ID “2” to the second target. Additionally, the temporary ID of the first target has a third smallest value and accordingly, the source may assign a control ID “3” to the first target.

However, since the temporary ID of the third target overlaps the temporary ID of the fourth target, it may not be possible for the source to assign a control ID to the third target and the fourth target.

FIG. 13illustrates using a call argument and a changed movement argument, when the temporary IDs ofFIG. 12overlap during the operation of identifying target devices to avoid communication collision.

The source may generate a call parameter based on a call argument, and may sequentially transmit the call parameter to target devices. For example, when the call argument is set to “3,” call parameters having values of “000” to “111” may be generated and the source may sequentially transmit the call parameters having values of “000” to “111” to the target devices. The target devices may compare their temporary IDs to a received call parameter. When the temporary IDs are identical to the call parameter, the target devices may transmit response signals to the source.

The source may receive the response signals, and may determine whether the temporary IDs overlap, based on the received response signals. For example, when the temporary IDs overlap, it may not be possible to assign control IDs to the target devices. Conversely, when the temporary IDs do not overlap, the source may assign control IDs to the target devices, respectively.

Referring toFIG. 13, a reference point, a call argument, and a movement argument are set to an MSB, “3,” and “1,” respectively. Since control IDs are assigned in advance to the first target, the second target, and the n-th target, respectively, the source may transmit, to the third target and the fourth target, an access standard instruction including the movement argument of “1”. The third target and the fourth target may update their temporary IDs based on the reference point, the call argument, and the movement argument. Accordingly, the third target may have a temporary ID “110”1310, and the fourth target may have a temporary ID “111”1320.

The source may sequentially transmit call parameters having values of “000” to “111.” Since the temporary ID of the third target is identical to a call parameter, the source may assign a control ID “4” to the third target, prior to the fourth target. Subsequently, the temporary ID of the fourth target may be identical to another call parameter, and accordingly the source may assign a control ID “5” to the fourth target. As described above, the source may assign control IDs to the first target to the n-th target, respectively.

Additionally, a final control ID may be assigned based on a maximum number of targets included in the system information area of the source illustrated inFIG. 15.

FIG. 14illustrates a method for avoiding a communication collision in a wireless power transmission. In some instances, the method ofFIG. 14may be performed by a target device.

In operation1410, the target device receives an access standard instruction from a source. The access standard instruction may include a reference point field, a call argument field, and a movement argument field.

In operation1420, the target device creates its temporary ID based on an access standard. For example, the target device may create the temporary ID based on a reference point, a call argument, and a movement argument.

In operation1430, the target device receives a call parameter from the source. The call parameter may be determined based on a call argument included in the access standard instruction. For example, when the call argument is set to “3,” the call parameter may have a value from “000” to “111.” The target device may sequentially receive the call parameter having values of “000” to “111.” Also, the target device may receive, from the source, an instruction corresponding to the call parameter. The instruction corresponding to the call parameter may include, for example, an instruction to call a temporary ID of a target device.

In operation1440, the target device determines whether the temporary ID is identical to the received call parameter.

When the temporary ID is different from the received call parameter, the target device does not transmit a response signal in response to the call parameter in operation1450. Subsequently, the target device may receive an updated call parameter from the source. For example, when the target device has a temporary ID “001,” and when a call parameter having a value of “000” is received, the target device may not transmit a response signal in response to the call parameter, and the target device may receive an updated call parameter having a value of “001.” On the other hand, if there is no need to charge the target device, or when the target device is not compatible with the source, the target device may not transmit a response signal in response to the call parameter.

When the temporary ID is identical to the received call parameter, the target device transmits a response signal in response to the call parameter in operation1460.

In operation1470, the target device determines whether a control ID is received from the source. The target device may receive the control ID from the source within a predetermined period of time, and may terminate the method ofFIG. 14. However, when the target device does not receive the control ID within the predetermined period of time, the target device may determine that the temporary ID of the target device is identical to a temporary ID of another target device, or that the response signal is not transferred to the source, and may repeat operations1410to1460.

FIG. 15illustrates a system information area of a source.

To perform communication between a source and a target, the source and the target may need to have their own IDs, in some instances. Accordingly, the source may call the target, or the target may call the source. Unique IDs may be assigned to the source and the target, respectively.

A unique ID of a source may be included in a system information area of the source, in manufacturing of a product. As illustrated inFIG. 15, the system information area may include, for example, a manufacturer ID area, a product type area, a model type area, a serial number area, a short ID area, and/or a standard version ID area.

The manufacturer ID area may include information on a manufacturer of a product that is operated as a source. The product type area may include information on a type of a product, information on a maximum output size for each product type, and information on a size of a resonator. The model type area may include information on a maximum number of targets that may be charged by a product.

Additionally, the serial number area may include a unique serial number assigned to a product in manufacturing of the product. The unique serial number may include, for example, a production date of the product. The short ID area may include a short ID created based on a unique serial number of a product. The short ID may be created by performing Exclusive OR (EOR), CRC, and/or the like with respect to the unique serial number. For example, when a serial number portion of the entire ID is extended due to a high production amount based on the production type, the short ID may reduce a time required by the source to identify targets.

Furthermore, the standard version ID area may include information on a standard of the source, for example, a maximum output of the source, a number of targets that may be charged by the source, an instruction that may be supported by the source, and/or the like.

The system information area of the source may additionally store information used to identify the source.

The unique ID of the source may refer to a unique serial number of a product, or a short ID.

FIG. 16illustrates a system information area of a target.

A unique ID of a target may be included in a system information area of the target, in manufacturing of a product. As illustrated inFIG. 16, the system information area may include, for example, a manufacturer ID area, a product type area, a battery type area, a serial number area, a short ID area, and a standard version ID area.

The manufacturer ID area may include information on a manufacturer of a product that is operated as a target. The product type area may include information on a type of a product, such as, for example, a TV, a camera, a mobile phone, or the like. Additionally, the product type area may include information on a charging scheme of a product, and information on power consumption of a product. The battery type area may include information on a type of a rechargeable battery loaded in a product, and information on a current capacity of the rechargeable battery.

Additionally, the serial number area may include a unique serial number assigned to a product in manufacturing of the product. The unique serial number may include, for example, a production date of the product. The short ID area may include a short ID created based on a unique serial number of a product. The short ID may be created by performing EOR, CRC, and/or the like with respect to the unique serial number. For example, when a device for receiving a wireless power exists around the target, the short ID may be used to prevent an error from occurring due to mutual interference.

Furthermore, the standard version ID area may include information on a standard of the target, for example, an instruction that may be supported by the target, information on power consumption, and/or the like.

The system information area of the target may additionally store information used to identify the target.

The unique ID of the target may refer to a unique serial number of a product, or a short ID.

The source and the target may identical each other by transmitting or receiving their own IDs to each other. However, when a unique ID of the source and a unique ID of the target are extended, a large amount of time may be required to identify the source and the target. Thus, a portion of unique IDs may be used to identify multiple targets.

FIGS. 17A and 17Billustrate distributions of a magnetic field in a feeder and a source resonator.

When a source resonator receives power supply through a separate feeder, magnetic fields may be formed in both the feeder and the source resonator.

Referring toFIG. 17A, as an input current flows in a feeder1710, a magnetic field1730may be formed. A direction1731of the magnetic field1730within the feeder1710may have a phase opposite to a phase of a direction1733of the magnetic field1730outside the feeder1710. The magnetic field1730formed by the feeder1710may cause an induced current to be formed in a source resonator1720. The direction of the induced current may be opposite to a direction of the input current.

Due to the induced current, a magnetic field1740may be formed in the source resonator1720. Directions of a magnetic field formed due to an induced current in all positions of the source resonator1720may be identical. Accordingly, a direction1741of the magnetic field1740formed by the source resonator1720may have the same phase as a direction1743of the magnetic field1740formed by the source resonator1720.

Consequently, when the magnetic field1730formed by the feeder1710and the magnetic field1740formed by the source resonator1720are combined, strength of the total magnetic field may decrease within the feeder1710, but may increase outside the feeder1710. In an example in which a power is supplied to the source resonator1720through the feeder1710configured as illustrated inFIG. 17, the strength of the total magnetic field may decrease in the center of the source resonator1720, but may increase outside the source resonator1720. When a magnetic field is randomly distributed in the source resonator1720, it may be difficult to perform impedance matching, since an input impedance may frequently vary. Additionally, when the strength of the total magnetic field is increased, an efficiency of wireless power transmission may be increased. Conversely, when the strength of the total magnetic field is decreased, the efficiency for wireless power transmission may be reduced. Accordingly, the power transmission efficiency may be reduced on average.

When a magnetic field in a target resonator is distributed as illustrated inFIG. 17Acurrent flowing in the source resonator1720may be induced by the input current flowing in the feeder1710. The current flowing in the target resonator may be induced by a magnetic coupling between the source resonator1720and the target resonator. The current flowing in the target resonator may cause a magnetic field to be formed, so that an induced current may be generated in a feeder located in the target resonator. When a direction of a magnetic field within the feeder formed by the target resonator has a phase opposite to a phase of a direction of a magnetic field formed by the feeder and accordingly, the strength of the total magnetic field may be reduced.

FIG. 17Billustrates a wireless power transmitter in which a source resonator1750and a feeder1760have a common ground. The source resonator1750may include a capacitor1751. The feeder1760may receive an input of a radio frequency (RF) signal via a port1761.

For example, when the RF signal is received to the feeder1760, an input current may be generated in the feeder1760. The input current flowing in the feeder1760may cause a magnetic field to be formed, and a current may be induced in the source resonator1750by the magnetic field. Additionally, another magnetic field may be formed due to the induced current flowing in the source resonator1750. The direction of the input current flowing in the feeder1760may have a phase opposite to a phase of a direction of the induced current flowing in the source resonator1750. Accordingly, in a region between the source resonator1750and the feeder1760, a direction1771of the magnetic field formed due to the input current may have the same phase as a direction1773of the magnetic field formed due to the induced current, and thus the strength of the total magnetic field may increase. Conversely, within the feeder1760, a direction1781of the magnetic field formed due to the input current may have a phase opposite to a phase of a direction1783of the magnetic field formed due to the induced current, and thus the strength of the total magnetic field may decrease. Therefore, the strength of the total magnetic field may decrease in the center of the source resonator1750, but may increase outside the source resonator1750.

The feeder1760may determine an input impedance by adjusting an internal area of the feeder1760. The input impedance refers to an impedance viewed in a direction from the feeder1760to the source resonator1750. When the internal area of the feeder1760is increased, the input impedance may be increased. Conversely, when the internal area of the feeder1760is reduced, the input impedance may be reduced. Since the magnetic field is randomly distributed in the source resonator1750despite a reduction in the input impedance, a value of the input impedance may vary depending on a location of a target device. Accordingly, a separate matching network may be required to match the input impedance to an output impedance of a power amplifier. For example, when the input impedance is increased, a separate matching network may be used to match the increased input impedance to a relatively low output impedance.

When a target resonator has the same configuration as the source resonator1750, and when a feeder of the target resonator has the same configuration as the feeder1760, a separate matching network may be required, because a direction of a current flowing in the target resonator has a phase opposite to a phase of a direction of an induced current flowing in the feeder of the target resonator.

FIG. 18Aillustrates a wireless power transmitter.

Referring toFIG. 18A, the wireless power transmitter may include a source resonator1810, and a feeding unit1820. The source resonator1810may include a capacitor1811. The feeding unit1820may be electrically connected to both ends of the capacitor1811.

FIG. 18Billustrates, in detail, a structure of the wireless power transmitter ofFIG. 18A. The source resonator1810may include a first transmission line, a first conductor1841, a second conductor1842, and at least one first capacitor1850.

The first capacitor1850may be inserted in series between a first signal conducting portion1831and a second signal conducting portion1832in the first transmission line, and an electric field may be confined within the first capacitor1850. For example, the first transmission line may include at least one conductor in an upper portion of the first transmission line, and may also include at least one conductor in a lower portion of the first transmission line. Current may flow through the at least one conductor disposed in the upper portion of the first transmission line, and the at least one conductor disposed in the lower portion of the first transmission line may be electrically grounded. For example, a conductor disposed in an upper portion of the first transmission line may be separated into and thereby be referred to as the first signal conducting portion1831and the second signal conducting portion1832. A conductor disposed in a lower portion of the first transmission line may be referred to as a first ground conducting portion1833.

As illustrate inFIG. 18B, the source resonator1810may have a two-dimensional (2D) structure. The first transmission line may include the first signal conducting portion1831and the second signal conducting portion1832in the upper portion of the first transmission line. In addition, the first transmission line may include the first ground conducting portion1833in the lower portion of the first transmission line. The first signal conducting portion1831and the second signal conducting portion1832may be disposed to face the first ground conducting portion1833. The current may flow through the first signal conducting portion1831and the second signal conducting portion1832.

Additionally, one end of the first signal conducting portion1831may be electrically connected (i.e., shorted) to the first conductor1841, and another end of the first signal conducting portion1831may be connected to the first capacitor1850. One end of the second signal conducting portion1832may be shorted to the second conductor1842, and another end of the second signal conducting portion1832may be connected to the first capacitor1850. Accordingly, the first signal conducting portion1831, the second signal conducting portion1832, the first ground conducting portion1833, and the conductors1841and1842may be connected to each other, so that the source resonator1810may have an electrically closed-loop structure. The term “loop structure” as used herein may include, for example, a polygonal structure such as a circular structure, a rectangular structure, or the like that forms a circuit which is electrically closed. The first capacitor1850may be inserted into an intermediate portion of the first transmission line. For example, the first capacitor1850may be inserted or otherwise positioned into a space between the first signal conducting portion1831and the second signal conducting portion1832. The first capacitor1850may be configured as a lumped element, a distributed element, or the like. For example, a distributed capacitor configured as a distributed element may include zigzagged conductor lines and a dielectric material that has a high permittivity between the zigzagged conductor lines.

When the first capacitor1850is instead into the first transmission line, the source resonator1810may have a characteristic of a metamaterial. The metamaterial indicates a material having a predetermined electrical property that has not been discovered in nature, and thus, may have an artificially designed structure. An electromagnetic characteristic of the materials existing in nature may have a unique magnetic permeability or a unique permittivity. Most materials may have a positive magnetic permeability or a positive permittivity.

In the case of most materials, a right hand rule may be applied to an electric field, a magnetic field, and a pointing vector, and thus, the corresponding materials may be referred to as right handed materials (RHMs). However, the metamaterial that has a magnetic permeability or a permittivity absent in nature may be classified into an epsilon negative (ENG) material, a mu negative (MNG) material, a double negative (DNG) material, a negative refractive index (NRI) material, a left-handed (LH) material, and the like, based on a sign of the corresponding permittivity or magnetic permeability.

When a capacitance of the first capacitor1850inserted as the lumped element is appropriately determined, the source resonator1810may have the characteristic of the metamaterial. Because the source resonator1810may have a negative magnetic permeability by appropriately adjusting the capacitance of the first capacitor1850, the source resonator1810may also be referred to as an MNG resonator. Various criteria may be applied to determine the capacitance of the first capacitor1850. For example, the various criteria may include a criterion for enabling the source resonator1810to have the characteristic of the metamaterial, a criterion for enabling the source resonator1810to have a negative magnetic permeability in a target frequency, a criterion for enabling the source resonator1810to have a zeroth order resonance characteristic in the target frequency, and the like. Based on at least one criterion among the aforementioned criteria, the capacitance of the first capacitor1850may be determined.

The source resonator1810, also referred to as the MNG resonator1810, may have a zeroth order resonance characteristic of having, as a resonance frequency, a frequency when a propagation constant is “0”. Because the source resonator1810may have the zeroth order resonance characteristic, the resonance frequency may be independent with respect to a physical size of the MNG resonator1810. By appropriately designing the first capacitor1850, the MNG resonator1810may sufficiently change the resonance frequency. Accordingly, the physical size of the MNG resonator1810may not be changed.

In a near field, the electric field may be concentrated on the first capacitor1850inserted into the first transmission line. Accordingly, due to the first capacitor1850, the magnetic field may become dominant in the near field. The MNG resonator1810may have a relatively high Q-argument using the first capacitor1850of the lumped element, and thus, it is possible to enhance an efficiency of power transmission. For example, the Q-argument may indicate a level of an ohmic loss or a ratio of a reactance with respect to a resistance in the wireless power transmission. The efficiency of the wireless power transmission may increase according to an increase in the Q-argument.

In some embodiments, a magnetic core may be further provided to pass through the MNG resonator1810. The magnetic core may increase the power transmission distance.

As illustrated inFIG. 18B, the feeding unit1820may include a second transmission line, a third conductor1871, a fourth conductor1872, a fifth conductor1881, and a sixth conductor1882.

The second transmission line may include a third signal conducting portion1861and a fourth signal conducting portion1862in an upper portion of the second transmission line. In addition, the second transmission line may include a second ground conducting portion1863in a lower portion of the second transmission line. The third signal conducting portion1861and the fourth signal conducting portion1862may be disposed to face the second ground conducting portion1863. Current may flow through the third signal conducting portion1861and the fourth signal conducting portion1862.

Additionally, one end of the third signal conducting portion1861may be shorted to the third conductor1871, and another end of the third signal conducting portion1861may be connected to the fifth conductor1881. One end of the fourth signal conducting portion1862may be shorted to the fourth conductor1872, and another end of the fourth signal conducting portion1862may be connected to the sixth conductor1882. The fifth conductor1881may be connected to the first signal conducting portion1831, and the sixth conductor1882may be connected to the second signal conducting portion1832. The fifth conductor1881and the sixth conductor1882may be connected in parallel to both ends of the first capacitor1850. In addition, the fifth conductor1881and the sixth conductor1882may be used as input ports to receive an input of an RF signal.

Accordingly, the third signal conducting portion1861, the fourth signal conducting portion1862, the second ground conducting portion1863, the third conductor1871; the fourth conductor1872, the fifth conductor1881, the sixth conductor1882, and the source resonator1810may be connected to each other, so that the source resonator1810and the feeding unit1820may have an electrically closed-loop structure. When an RF signal is received via the fifth conductor1881or the sixth conductor1882, an input current may flow in the feeding unit1820and the source resonator1810, a magnetic field may be formed due to the input current, and a current may be induced to the source resonator1810by the formed magnetic field. A direction of the input current flowing in the feeding unit1820may be identical to a direction of the induced current flowing in the source resonator1810and thus, strength of the total magnetic field may increase in the center of the source resonator1810, but may decrease outside the source resonator1810. The direction of the input current, and the direction of the induced current will be further described with reference toFIGS. 19A and 19B.

An input impedance may be determined based on an area of a region between the source resonator1810and the feeding unit1820and accordingly, a separate matching network used to match the input impedance to an output impedance of a power amplifier may not be required. For example, even when the matching network is used, the input impedance may be determined by adjusting a size of the feeding unit1820and thus, a structure of the matching network may be simplified. The simplified structure of the matching network may minimize a matching loss of the matching network.

The second transmission line, the third conductor1871, the fourth conductor1872, the fifth conductor1881, and the sixth conductor1882may form the same structure as the source resonator1810. When the source resonator1810has a loop structure, the feeding unit1820may also have a loop structure. For example, when the source resonator1810has a circular structure, the feeding unit1820may also have a circular structure.

The above-described configuration of the source resonator1810and configuration of the feeding unit1820may equally be applied to the target resonator and the feeding unit of the target resonator, respectively. When the feeding unit of the target resonator is configured as described above, the feeding unit may match an output impedance of the target resonator and an input impedance of the feeding unit, by adjusting a size of the feeding unit. Accordingly, a separate matching network may not be used in some instances.

FIG. 19Aillustrates a distribution of a magnetic field within a source resonator based on feeding of a feeding unit.FIG. 19Amore briefly illustrates the source resonator1810and the feeding unit1820ofFIG. 18A.FIG. 19Billustrates an equivalent circuit of a feeding unit1940, and an equivalent circuit of a source resonator1950.

A feeding operation may refer to supplying a power to a source resonator in a wireless power transmitter, or refer to supplying an AC power to a rectification unit in a wireless power receiver.FIG. 19Aillustrates a direction of an input current flowing in the feeding unit, and a direction of an induced current induced in the source resonator. Additionally,FIG. 19Aillustrates a direction of a magnetic field formed due to the input current of the feeding unit, and a direction of a magnetic field formed due to the induced current of the source resonator.

Referring toFIG. 19A, a fifth conductor or a sixth conductor of the feeding unit may be used as an input port1910. The input port1910may receive an input of an RF signal. The RF signal may be output from a power amplifier. The power amplifier may increase or decrease the amplitude of the RF signal, on demand by a target device. The RF signal received by the input port1910may be displayed in the form of an input current flowing in the feeding unit. The input current may flow in a clockwise direction in the feeding unit, along a transmission line of the feeding unit. The fifth conductor of the feeding unit may be electrically connected to the source resonator. In addition, the fifth conductor may be connected to a first signal conducting portion of the source resonator. Accordingly, the input current may flow in the source resonator, as well as, in the feeding unit. The input current may flow in a counterclockwise direction in the source resonator. The input current flowing in the source resonator may cause a magnetic field to be formed, so that an induced current may be generated in the source resonator due to the magnetic field. The induced current may flow in a clockwise direction in the source resonator. The induced current may transfer energy to a capacitor of the source resonator, and a magnetic field may be formed due to the induced current. The input current flowing in the feeding unit and the source resonator may be indicated by a solid line ofFIG. 19A, and the induced current flowing in the source resonator may be indicated by a dotted line ofFIG. 19A.

A direction of a magnetic field formed due to a current may be determined based on the right hand rule. As illustrated inFIG. 19A, within the feeding unit, a direction1921of a magnetic field formed due to the input current flowing in the feeding unit may be identical to a direction1923of a magnetic field formed due to the induced current flowing in the source resonator. Accordingly, strength of the total magnetic field may increase within the feeding unit.

Additionally, in a region between the feeding unit and the source resonator, a direction1933of a magnetic field formed dye to the input current flowing in the feeding unit has a phase opposite to a phase of a direction1931of a magnetic field formed due to the induced current flowing in the source resonator, as illustrated inFIG. 19A. Accordingly, strength of the total magnetic field may decrease in the region between the feeding unit and the source resonator.

Typically, the strength of a magnetic field decreases in the center of a source resonator with the loop structure, and increases outside the source resonator. However, referring toFIG. 19A, the feeding unit may be electrically connected to both ends of a capacitor of the source resonator, and accordingly the induced current of the source resonator may flow in the same direction as the input current of the feeding unit. Since the induced current of the source resonator flows in the same direction as the input current of the feeding unit, the strength of the total magnetic field may increase within the feeding unit, and may decrease outside the feeding unit. As a result, the strength of the total magnetic field may increase in the center of the source resonator with the loop structure, and may decrease outside the source resonator, due to the feeding unit. Thus, the strength of the total magnetic field may be equalized within the source resonator. Additionally, the power transmission efficiency for transferring a power from the source resonator to a target resonator may be in proportion to the strength of the total magnetic field formed in the source resonator. When the strength of the total magnetic field increases in the center of the source resonator, the power transmission efficiency may also increase.

Referring toFIG. 19B, the feeding unit1940and the source resonator1950may be expressed by the equivalent circuits. An input impedance Zinviewed in a direction from the feeding unit1940to the source resonator1950may be computed, as given in Equation 1.

In Equation 1, M denotes a mutual inductance between the feeding unit1940and the source resonator1950, ω denotes a resonance frequency between the feeding unit1940and the source resonator1950, and Z denotes an impedance viewed in a direction from the source resonator1950to a target device. The input impedance Zinmay be in proportion to the mutual inductance M. Accordingly, the input impedance Zinmay be controlled by adjusting the mutual inductance M. The mutual inductance M may be adjusted based on an area of a region between the feeding unit1940and the source resonator1950. The area of the region between the feeding unit1940and the source resonator1950may be adjusted based on a size of the feeding unit1940. The input impedance Zinmay be determined based on the size of the feeding unit1940, and thus a separate matching network may not be required to perform impedance matching with an output impedance of a power amplifier.

In a target resonator and a feeding unit included in a wireless power receiver, a magnetic field may be distributed as illustrated inFIG. 19A. For example, the target resonator may receive a wireless power from a source resonator, via magnetic coupling. Due to the received wireless power, an induced current may be generated in the target resonator. A magnetic field formed due to the induced current in the target resonator may cause another induced current to be generated in the feeding unit. When the target resonator is connected to the feeding unit as illustrated inFIG. 19A, the induced current generated in the target resonator may flow in the same direction as the induced current generated in the feeding unit. Thus, strength of the total magnetic field may increase within the feeding unit, but may decrease in a region between the feeding unit and the target resonator.

FIG. 20illustrates an example of an electric vehicle charging system.

Referring toFIG. 20, an electric vehicle charging system2000includes a source system2010, a source resonator2020, a target resonator2030, a target system2040, and an electric vehicle battery2050.

The electric vehicle charging system2000may have a similar structure to the wireless power transmission and charging system ofFIG. 1. The source system2010and the source resonator2020in the electric vehicle charging system2000may function as a source. Additionally, the target resonator2030and the target system2040in the electric vehicle charging system2000may function as a target.

The source system2010may include an AC/DC converter, a power detector, a power converter, a control/communication unit, similarly to the source device110ofFIG. 1. The target system2040may include a rectification unit, a DC/DC converter, a switch unit, a charging unit, and a control/communication unit, similarly to the target device120ofFIG. 1.

The electric vehicle battery2050may be charged by the target system2040.

The electric vehicle charging system2000may use a resonant frequency in a band of a few kilohertz (KHz) to tens of MHz.

The source system2010may generate power, based on a type of charging vehicle, a capacity of a battery, and a charging state of a battery, and may supply the generated power to the target system2040.

The source system2010may control the source resonator2020and the target resonator2030to be aligned. For example, when the source resonator2020and the target resonator2030are not aligned, the control/communication unit of the source system2010may transmit a message to the target system2040, and may control alignment between the source resonator2020and the target resonator2030.

For example, when the target resonator2030is not located in a position enabling maximum magnetic resonance, the source resonator2020and the target resonator2030may not be aligned. When a vehicle does not stop accurately, the source system2010may induce a position of the vehicle to be adjusted, and may control the source resonator2020and the target resonator2030to be aligned.

The source system2010and the target system2040may transmit or receive an ID of a vehicle, or may exchange various messages, through communication.

The descriptions ofFIGS. 2 through 19may be applied to the electric vehicle charging system2000. However, the electric vehicle charging system2000may use a resonant frequency in a band of a few KHz to tens of MHz, and may transmit power that is equal to or higher than tens of watts to charge the electric vehicle battery2050.

FIGS. 21A through 22Billustrate examples of applications in which a wireless power receiver and a wireless power transmitter may be mounted.

FIG. 21Aillustrates an example of wireless power charging between a pad2110and a mobile terminal2120, andFIG. 21Billustrates an example of wireless power charging between pads2130and2140and hearing aids2150and2160.

In an example, a wireless power transmitter may be mounted in the pad2110, and a wireless power receiver may be mounted in the mobile terminal2120. The pad2110may be used to charge a single mobile terminal, namely the mobile terminal2120.

In another example, two wireless power transmitters may be respectively mounted in the pads2130and2140. The hearing aids2150and2160may be used for a left ear and a right ear, respectively. In this example, two wireless power receivers may be respectively mounted in the hearing aids2150and2160.

FIG. 22Aillustrates an example of wireless power charging between an electronic device2210that is inserted into a human body, and a mobile terminal2220.FIG. 22Billustrates an example of wireless power charging between a hearing aid2230and a mobile terminal2240.

In an example, a wireless power transmitter and a wireless power receiver may be mounted in the mobile terminal2220. In this example, another wireless power receiver may be mounted in the electronic device2210. The electronic device2210may be charged by receiving power from the mobile terminal2220.

In another example, a wireless power transmitter and a wireless power receiver may be mounted in the mobile terminal2240. In this example, another wireless power receiver may be mounted in the hearing aid2230. The hearing aid2230may be charged by receiving power from the mobile terminal2240. Low-power electronic devices, for example Bluetooth earphones, may also be charged by receiving power from the mobile terminal2240.

FIG. 23illustrates an example of a wireless power transmitter and a wireless power receiver.

InFIG. 23, a wireless power transmitter2310may be mounted in each of the pads2130and2140ofFIG. 21B. Additionally, the wireless power transmitter2310may be mounted in the mobile terminal2240ofFIG. 22B.

In addition, a wireless power receiver2320may be mounted in each of the hearing aids2150and2160ofFIG. 21B.

The wireless power transmitter2310may have a similar configuration to the source device110ofFIG. 1. For example, the wireless power transmitter2310may include a unit configured to transmit power using magnetic coupling.

As illustrated inFIG. 23, the wireless power transmitter2310includes a communication/tracking unit2311. The communication/tracking unit2311may communicate with the wireless power receiver2320, and may control an impedance and a resonant frequency to maintain a wireless power transmission efficiency. Additionally, the communication/tracking unit2311may perform similar functions to the power converter114and the control/communication unit115ofFIG. 1.

The wireless power receiver2320may have a similar configuration to the target device120ofFIG. 1. For example, the wireless power receiver2320may include a unit configured to wirelessly receive power and to charge a battery. As illustrated inFIG. 23, the wireless power receiver2320includes a target resonator, a rectifier, a DC/DC converter, and a charging circuit. Additionally, the wireless power receiver2320may include a control/communication unit2323.

The communication/control unit2323may communicate with the wireless power transmitter2310, and may perform an operation to protect overvoltage and overcurrent.

The wireless power receiver2320may include a hearing device circuit2321. The hearing device circuit2321may be charged by the battery. The hearing device circuit2321may include a microphone, an analog-to-digital converter (ADC), a processor, a digital-to-analog converter (DAC), and a receiver. For example, the hearing device circuit2321may have the same configuration as a hearing aid.

The software may include a computer program, a piece of code, an instruction, or some combination thereof, for independently or collectively instructing or configuring the processing device to operate as desired. Software and data may be embodied permanently or temporarily in any type of machine, component, physical or virtual equipment, computer storage medium or device, or in a propagated signal wave capable of providing instructions or data to or being interpreted by the processing device. The software also may be distributed over network coupled computer systems so that the software is stored and executed in a distributed fashion. In particular, the software and data may be stored by one or more computer readable recording mediums. The computer readable recording medium may include any data storage device that can store data which can be thereafter read by a computer system or processing device. Examples of the computer readable recording medium include read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, optical data storage devices. Also, functional programs, codes, and code segments for accomplishing the example embodiments disclosed herein can be easily construed by programmers skilled in the art to which the embodiments pertain based on and using the flow diagrams and block diagrams of the figures and their corresponding descriptions as provided herein.