KR102342344B1 - Wireless power transmission system - Google Patents

Abstract

The present invention provides a wireless power transmission system including a power transmitter configured to transmit power to a plurality of power receivers by phase controlling each of a plurality of power receivers and a plurality of array antennas.

Description

Wireless power transmission system {Wireless power transmission system}

The present invention relates to a wireless power transmission system for transmitting power for charging a mobile phone/wearable device or a sensor device, and more particularly, a plurality of receiving end devices that receive power on one channel receive power from one power transmitting end It relates to a wireless power transmission system capable of supplying power to a plurality of receiving end devices by proposing a scheduling mechanism for receiving .

As the Internet of Things (IoT) is widespread and massively expanded to various fields for monitoring and controlling the surrounding environment, numerous sensor devices are being used everywhere, extending the lifespan other than constant power and batteries in terms of power supply. The need for a method has increased. Recently, wireless charging technology has been grafted as a method of extending the lifespan other than power and battery. Recently, a charging technology using Radio Frequency (RF) has been studied for wireless charging of mobile devices or remote IoT devices. However, the method of transmitting power using RF has a disadvantage in that transmission efficiency is very weak.

Recently, in order to overcome the transmission efficiency of RF wireless power transmission, a technique of beamforming power to a specific location has been introduced.

The core of the technology of beamforming power to a specific location through RF wireless power transmission is to precisely form and transmit power to a desired location. Therefore, in order to beamform power to a specific position of the receiving end, the transmitting end that transmits power needs to know the location of the receiving end. The receiving end sends a specific pattern signal to inform the power transmitting end of its location so that the transmitting end recognizes the location. This method is known as retro-reflective power beamforming.

In the past, the beamforming method was proposed as a structure for transmitting power to a single receiving device, or the transmitting end transmits power without a scheduling technique, and when the optimal power is received, the receiving end informs the transmitting end of the information. . This method is inefficient and wastes channel resources when a plurality of receiving terminals exist.

Recently, in order for a plurality of receivers to receive power from one power transmitter, not only structural considerations of the transmitter and receiver, but also appropriate scheduling are required, and research to solve this problem is in progress.

It is an object of the present invention to provide a wireless power transmission system capable of transmitting and receiving power through efficient scheduling while solving the power supply problem of an existing power receiving end device by applying beamforming, a wireless power transmission technology, to wireless network communication.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned may be understood by the following description, and will be more clearly understood by the examples of the present invention. It will also be readily apparent that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the appended claims.

The wireless power transmission system according to the present invention may include a power transmitter configured to transmit power to the plurality of power receivers by controlling the phases of each of a plurality of power receivers and a plurality of array antennas.

The wireless power transmission system according to the present invention has the advantage of efficiently supplying power to a power receiving device using a power channel in a wireless environment.

In addition, in the wireless power transmission system according to the present invention, the power transmitting end calculates the phase changed through a beacon received from the power receiving device to determine the position, thereby intensively transmitting power to the location of the corresponding power receiving device at the same time There are advantages that can be

In addition, the wireless power transmission system according to the present invention proposes a transmission/reception structure capable of transmitting power to multiple devices and a scheduling method for efficiently allocating slaves for power transmission, when a plurality of power receiving devices exist Also, there is an advantage in that power can be exchanged without mutual interference by scheduling.

In addition, the wireless power transmission system according to the present invention, using RF wireless power transmission technology, if the receiving end (cell phone / wearable device, sensor, etc.) device is located within the RF reach even if it is not located in a limited place where power supply is possible, one It is possible to transmit power to a sensor device through beamforming in the same channel of There is this.

In addition to the above-described effects, the specific effects of the present invention will be described together while describing specific details for carrying out the invention below.

1 is a structural diagram showing a wireless power transmission system according to the present invention.
2 is a detailed structural diagram showing a wireless power transmission system according to the present invention.
3 is a diagram illustrating a general MAC Superframe structure.
4 is a diagram illustrating a superframe structure applied to a wireless power transmission system according to the present invention.
5 is a diagram illustrating an architecture of a wireless power transmission system according to the present invention.
6 is a diagram illustrating an example of one-to-many power transmission/reception between a master and a slave.
7 is a diagram illustrating an operation flow of the RF Control Protocol between the PTU and the PRU within the master and the slave.

It should be noted that, in the following description, only parts necessary for understanding the embodiments of the present invention will be described, and descriptions of other parts will be omitted so as not to obscure the gist of the present invention.

The terms or words used in the present specification and claims described below should not be construed as being limited to their ordinary or dictionary meanings, and the inventors have appropriate concepts of terms to describe their invention in the best way. It should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined in Accordingly, the embodiments described in this specification and the configurations shown in the drawings are only preferred embodiments of the present invention, and do not represent all of the technical spirit of the present invention, so various equivalents that can be substituted for them at the time of the present application It should be understood that there may be variations and variations.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

According to the present invention, since one power transmitter transmits power to the power receiver through a single channel, the lifespan of the sensor device can be ultimately extended through power transmission through efficient scheduling in a network composed of a plurality of receivers.

1 is a structural diagram showing a wireless power transmission system according to the present invention.

The power transmitter of FIG. 1 serves as a master, and the power receiver acts as a slave.

Master and Slave can be configured in a structure including T-TX/RX, which is a communication part for general communication, and Power Transmitting Unit (PTU) or Power Receiving Unit (PRU).

The master and the slave perform wireless data transmission/reception through T-TX/RX in common.

By performing Clear Channel Assessment (CCA) between multiple transmit/receive nodes, a wireless communication environment is configured so that data can be exchanged without collision in the corresponding frequency channel. In the process of CCA, energy detection or channel sensing for a corresponding frequency is performed to determine whether a channel is available or not. After the channel connection between the master slaves through CCA is completed, the master can know the number and information of the slaves through wireless data communication on the corresponding channel.

In terms of power transmission and reception, the master may be configured with a plurality of array antennas for wireless power transmission through beamforming, and may include a PTU that structurally performs the role of power transmission. The PTU consists of Power TX for power transmission and RX for receiving signals such as OOK. The master receives the Power Beacon (PB) containing the phase information that can determine the position of the slave through RX, and from it, the position of the slave is determined and beamformed from the Power Tx to the corresponding position, and power is transmitted through the Power Channel for a certain period of time. carry out

A slave may consist of one antenna or a plurality of array antennas like the master, and structurally includes a PRU that plays a role of power reception. The PRU consists of a Power RX part for power reception and a TX for transmitting a specific pattern signal by On-Off Keying (OOK), etc., and additionally it may include a Master Beacon Receiver (MBR) that can acquire information from the Master Beacon. can As a Master Beacon Receiver (MBR), an envelope detector that can be configured with a simple circuit can be used.

The MBR can perform TX Enabling by receiving and reading the master beacon (MB) that is coded by the master and transmitted by Amplitude-shift Keying (ASK). As TX is enabled, a specific pattern signal can be generated to transmit PB to the master.

2 is a detailed structural diagram showing a wireless power transmission system according to the present invention.

2 shows an example of a transmitting and receiving end. It consists of DAC/LFP/MIXER/PA and multiple array antennas so that power can be beamformed to the receiving end of the transmitting end. Consists of. The calculation for calculating the position of the receiving end and the operation for beamforming are all processed in the baseband of the transmitting end.

The receiving end can be composed of a rectifier receiving power, an MBR r to receive the master beacon received from the power channel, and a part for transmitting the power beacon.

3 is a diagram illustrating a general MAC Superframe structure.

First, the existing Superframe (SF) is composed of a beacon, a Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) section, and a plurality of Data Slots (D-Slots) as shown in FIG. 3 .

When the master sends a beacon to form a network, adjacent slaves receive it. The slaves receiving the beacon participate in the network by sending a network join request message (Join Request) to the master in the CSMA/CA section and receiving a response. The master allocates each slave participating in the network to a specific D-Slot through scheduling to enable data transmission and reception. The time of D-Slot is not fixed and can be dynamically changed according to the request of the slave. Thereafter, the slave may perform data transmission and reception in the allocated D-Slot. Superframes repeat over time.

The present invention proposes a new superframe structure capable of transmitting power through efficient scheduling while solving the power supply problem of an existing power receiving end device by applying beamforming.

In general, in communication, the MAC layer requests the PHY layer to perform CCA in order for multiple transmission/reception nodes to exchange data without collision. Through the CCA process, Energy Detection or Channel Sensing is performed at the PHY stage, and whether the corresponding frequency channel is available or not is considered.

However, in a structure that does not use CCA, separate scheduling is required for the PTU and PRU to prevent collisions during wireless power transmission between the master and multiple slaves. For example, when Slave 1 and Slave 2 simultaneously transmit a PB for informing their location, a method for avoiding collision is required. Therefore, it is necessary for the master to use a superframe structure for wireless power transmission without collision with a specific slave by transmitting omnidirectional scheduling information such as assigning priority to a slave to multiple slaves in MB.

4 is a diagram illustrating a superframe structure applied to a wireless power transmission system according to the present invention.

Superframe is largely composed of MB, PB, and Channel Time Allocation (CTA) sections. In a network composed of one power transmitter and multiple power receivers, the channel connection between the transmitter and receiver has already been completed by a wireless communication method such as Bluetooth or Wi-Fi. and information of each power receiving end. Therefore, unlike the existing communication superframe, there is a structurally distinct difference in that there is no CSMA/CA section for channel connection between the master and the slave. In addition, in addition to the master beacon (MB) for network synchronization, a power beacon (PB) for informing the location of the power receiver is additionally used.

The master can know the information of the slaves in the same network through other wireless communication methods (such as Bluetooth or Wi-Fi). The slave information may include user authentication, device information, remaining power, and the like.

The master schedules power transmission slot (P-slot) allocation to a plurality of slaves based on this information. The master omni-directionally transmits MB to multiple slaves to transmit beacon information through a single channel. MB is Amplitude-shift Keying (ASK) coded, transmitted from one antenna to multiple slaves, and plays a role in synchronizing slaves located within the same network as the master. In addition, it is possible to determine which slave to allocate to the P-Slot in the CTA section with information included in the MB. The MB frame may be composed of a preamble, a slave ID, a checksum, and the like.

After the transmission of the MB of the PTU, the slaves receiving the MB determine whether or not they can request power through the Slave ID included in the MB. The power receiver has a structure that can include an MBR that can be used as an envelope detector in the PRU, and can receive and read an MB that is ASK-coded and received as an MBR. The slave can check the Slave ID included in the MB through the MBR, and the corresponding slave can transmit PB to the master using a signal such as OOK by TX Enabling from MBR to TX.

The transmitter uses the information contained in the received PB to extract the phase of the signal incident from each transmit antenna, or uses a location recognition algorithm (MUSIC algorithm, etc.) to determine the location of the receiver to beamform power. After PB transmission, in one Power Slot (P-Slot), which is the entire section of the CTA, the transmitting end can beamform all antennas to the position of the corresponding receiving end calculated by the phase information to effectively transmit power. As the master beamforms, the Signal-to-Noise Ratio (SNR) increases. The superframe repeats the same structure over time, and the receiving end capable of receiving power may be dynamically changed according to the master's scheduling information.

5 is a diagram illustrating an architecture of a wireless power transmission system according to the present invention.

The architecture of the wireless power transmission system may consist of one power transmitter and a plurality of power receivers in a one-to-many power transmission/reception structure. The power transmitting end is composed of a plurality of array antennas for beamforming, and may be a device to which power is always connected. The power receiving end can be a variety of devices including mobile phones/wearable devices, sensors, etc., and it is a structure that can include the MBR for receiving the MB that is ASK-coded and transmitted in a single channel and identifying the slave ID included in the MB. .

Figure 5(a) shows CCA performed by other wireless communication methods for wireless communication channel connection between master and slave and MB transmission performed at the start of Superframe. The master can know the number of slaves participating in the network and slave information by connecting a channel through CCA performed by the slave before MB transmission. The master performs efficient slave scheduling for wireless power transmission based on this information. Thereafter, the Power TX of the PTU transmits to adjacent slaves including the Slave ID in the MB for allocating the slave to receive power in the P-Slot in the CTA. One of the array antennas is used to transmit MB in all directions.

Figure 5(b) shows power transmission and reception generated in P-Slot in PB transmission and CTA section of Superframe. In the RF wireless power transmission system, a total of two beacons, MB and PB, are used. The slave receives the ASK-coded MB through the MBR acting as an envelope detector and reads the information contained in the MB to check whether it is a slave capable of receiving power from the P-Slot. If it is the slave corresponding to the MB's Slave ID, the MBR transmits the PB containing the phase information to the PRU's TX to the PRU's TX by TX Enabling, so that the PRU's TX can determine its own location using a signal such as OOK to the master. do. The master extracts the phase information of the slave from the PB received in the RX in the PTU, calculates the position, and beamforms the position with Power TX using the array antenna to transmit power intensively during the P-Slot for the entire section of the CTA. can The slave receives power intensively through Power RX of the PRU. In this case, since all slots unassigned to the slaves adjacent to the slave receiving power intensively operate in the Rx mode, weak power may be received.

6 is a diagram illustrating an example of one-to-many power transmission/reception between a master and a slave.

One master and multiple slaves may exist in the network, and the number of slaves receiving power from the P-Slot may vary according to the master's scheduling. At the beginning of the superframe, the PTU transmits MB in all directions for the synchronization of the master and the allocation of the slave to receive power at the same time as the start.

A plurality of slaves that have received the MB determine whether they are designated slaves from the master by receiving and reading the ASK-coded MB through the MBR. For example, the slave checks the first incoming preamble of the MB through the MBR, reads the incoming Slave ID, and if it matches itself, it can recognize that it needs to transmit the PB. In the case of a slave assigned to the CTA section, the PRU transmits a PB to the master to request power for power charging. The transmitted PB includes phase information that can inform the location of the slave.

The master receives the PB through RX in the PTU and transmits power intensively by beamforming to the location of the slave using the array antenna during the P-Slot of the CTA section. When the P-Slot allocated to the corresponding slave is finished, a new superframe is started, and the above process is repeated over time.

7 is a diagram illustrating an operation flow of the RF Control Protocol between the PTU and the PRU within the master and the slave.

The PTU and PRU sequentially and repeatedly perform configuration, beacon transmission, and RF WPT. Configuration is performed at the beginning of the connection between the PTU and the PRU, and first, the RF WPT connection between the PTU and the PRU is performed. When RF WPT Connection is completed, configure PRU Static Parameter, Station Probe Response, PRU Dynamic Parameter, and Station Dynamic Parameter to complete the configuration. Thereafter, the PTU transmits the MB PTU Beacon to the adjacent slave in all directions. Among the slaves that have received the PTU Beacon, the PRU of the slave allocated for wireless power transmission transmits the PRU Beacon to the PTU. When the environment for power transmission is completed in this way, the PTU performs power transfer from the RF WPT to the corresponding PRU. Therefore, the PRU may use the received power to charge the power of the device. After that, the process except for Configuration is continuously repeated over time.

The wireless power transmission system of the present invention has an RF wireless power transmission environment in which a power transmitting end composed of a plurality of array antennas and a plurality of power receiving end nodes exist, the power transmitting end serves as a master, and the power receiving end is a slave Performs the role of (slave). Master and Slave include T-TX/RX and Power Transmitting Unit (PTU), which are communication parts for general communication, and Power Transmitting Unit (PTU) of the power transmitter can beamform power. It includes a structure that allows individual phase control of a plurality of antennas, and the Power Transmitting Unit (PTU) of the power transmitter extracts the phase or phase difference received from the individual antennas, and based on this, the phase of each antenna is determined. It includes a structure that controls and forms power to a specific location, and the power receiver receives T-TX/RX, which is a communication part for general communication, and a power channel that converts a beamforming signal (CW: Continuous Wave) into power and a power channel. It has a structure including the MBR to receive the master beacon, and the Power Receiving Unit (PRU) composed of parts for transmitting the power beacon. It is a structure in which the channel connection is completed, and a system structure that dynamically schedules the allocation of a receiver to channel resources for power transmission between one transmitter and a plurality of receivers, and a MAC Superframe structure for the corresponding system. The proposed superframe is largely a master beacon It consists of (MB), Power Beacon (PB), and Channel Time Allocation (CTA) sections, and uses a beacon (PB) to inform the location of the power receiver in addition to the beacon (MB) for network synchronization and slave designation. , CTA The (Channel Time Allocation) section can consist of a single Power Slot (P-Slot) to transmit power by allocating it to a specific slave, synchronizing between slaves through the Master Beacon (MB), and which slave is currently located It informs whether the Beacon TX indicating TX is activated, and when the power receiving end is assigned to receive power by the MB, it transmits a beacon (PB) indicating the location of the power receiving end to the power transmitting end. It has a structure in which the Master Beacon Receiver (MBR), which can receive MB from the transmitter and read information, can be used as an envelope detector, and may have a structure including an envelope detector circuit in the power receiver.

Features, structures, effects, etc. described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, features, structures, effects, etc. illustrated in each embodiment can be combined or modified for other embodiments by a person skilled in the art to which the embodiments belong. Accordingly, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

In addition, although the embodiment has been described above, it is merely an example and does not limit the present invention, and those of ordinary skill in the art to which the present invention pertains are exemplified above in a range that does not depart from the essential characteristics of the present embodiment. It can be seen that various modifications and applications that have not been made are possible. For example, each component specifically shown in the embodiment can be implemented by modification. And differences related to such modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

Claims (8)

a plurality of power receivers; and
A plurality of antennas are provided, and after a wireless communication channel is formed with the plurality of power receivers through the plurality of antennas, scheduling information for wireless power transmission is sequentially generated to the plurality of power receivers, and the scheduling information is included transmits the master beacon in all directions so that the plurality of power receivers can receive it, and receives a power beacon including phase information of the specific power receiver from a specific power receiver to receive wireless power according to the scheduling information, A power transmitter to determine the location of the specific power receiver with the phase information included in the received power beacon, and beamforming the plurality of antennas to the identified location of the specific power receiver to transmit wireless power; and
The superframe for wireless communication between the plurality of power receivers and the power transmitter includes a master beacon, a power beacon, and a channel time allocation (CTA) period. According to claim 1,
A wireless power transmission system, characterized in that a wireless communication channel is formed by performing CCA (Clear Channel Assessment) between the plurality of power receivers and the power transmitter. delete According to claim 1,
The wireless power transmission system, characterized in that the plurality of power receivers determine whether they can request power through the Slave ID included in the master beacon. 5. The method of claim 4,
The specific power receiving end uses an On-off Keying (OOK) signal to transmit a power beacon to the power transmitting end. According to claim 1,
The wireless power transmission system, characterized in that the power transmitter transmits power to the specific power receiver through the CTA section. a communication unit having a plurality of antennas and performing wireless communication with a plurality of power receivers; and
After forming a wireless communication channel with the plurality of power receivers through the plurality of antennas, scheduling information for wireless power transmission is sequentially generated to the plurality of power receivers, and a master beacon including the scheduling information is transmitted to the plurality of power receivers. It transmits omnidirectional so that the power receiver can receive it, receives a power beacon including the phase information of the specific power receiver from a specific power receiver that will receive wireless power according to the scheduling information, and includes the received power beacon. A PTU (Power Transmitting Unit) for determining the position of the specific power receiving end with phase information and beamforming the plurality of antennas to the identified position of the specific power receiving end to transmit wireless power;
The superframe for wireless communication with the plurality of power receivers includes a master beacon, a power beacon, and a channel time allocation (CTA) period. 8. The method of claim 7,
The PTU is a power transmitter for a wireless power transmission system, characterized in that the phase control of the plurality of antennas individually so that the power beamforming.

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