KR20200065537A - Wireless power transmission system - Google Patents

Abstract

According to an embodiment of the present invention, provided is a wireless power transmission system which comprises: a plurality of power reception terminals; and a power transmission terminal controlling a phase of each of a plurality of array antennas to transmit power to the plurality of power reception terminals. Therefore, power transmission and reception can be performed through effective scheduling.

Description

Wireless power transmission system

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

As the Internet of Things (IoT) has become commonplace and scaled up in a wide range of fields for monitoring and control of the surrounding environment, numerous sensor devices are being used everywhere, and in terms of power supply, lifespan other than power and battery is always extended. The need for methods has increased. In recent years, wireless charging technology has been grafted as a method of extending lifespan other than a power source and a battery. Recently, charging technology using radio frequency (RF) has been studied for wireless charging of mobile devices or long-range IoT devices. However, the method of transmitting power using RF has a disadvantage that transmission efficiency is very weak.

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

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

Conventionally, the beamforming method is 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 transmits power in such a way as to inform the transmitting end of the information. . This method is not only inefficient when multiple receiving terminals exist, but also wastes channel resources.

Recently, in order for a plurality of receiving terminals to receive power from one power transmitting terminal, not only structural consideration of the transmitting/receiving terminal but also proper scheduling is necessary, and research is being conducted to solve this.

An object of the present invention is to provide a wireless power transmission system capable of solving the power supply problem of an existing power receiving end device by applying beamforming, which is a wireless power transmission technology, to wireless network communication, and at the same time enabling power transmission and reception through efficient scheduling.

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 can be understood by the following description, and will be more clearly understood by embodiments of the present invention. In addition, it will be readily appreciated that the objects and advantages of the present invention can be realized by means of the appended claims and combinations thereof.

The wireless power transmission system according to the present invention may include a power transmission end that phase-controls each of a plurality of power reception ends and a plurality of array antennas to transmit power to the plurality of power reception ends.

The wireless power transmission system according to the present invention has an 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 terminal intensively transmits power to the location of the corresponding power receiving device simultaneously by calculating the phase by calculating the phase changing through the beacon received from the power receiving device. There is an advantage.

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 presents a scheduling method for efficiently allocating slaves for power transmission, where multiple power receiving devices are present. Edo also has the advantage of being able to send and receive power without mutual interference by scheduling.

In addition, the wireless power transmission system according to the present invention, if the receiving end (mobile phone / wearable device, sensor, etc.) device using RF wireless power transmission technology is located within the RF reach even if the power supply is not located in a limited place, one It is possible to transmit power to the sensor device through beamforming in the same channel, and wireless power transmission is possible not only to fixed receiving devices, but also to flexible receiving devices that continuously change position by calculating continuously changing phases. There is this.

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

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 showing a general MAC Superframe structure.
4 is a view showing a superframe structure applied to the wireless power transmission system according to the present invention.
5 is a diagram showing the 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 and reception between a master and a slave.
7 is a diagram showing the operation flow of the RF Control Protocol between the PTU and the PRU in the master and slave.

It should be noted that in the following description, only parts necessary for understanding the embodiments of the present invention are described, and descriptions of other parts will be omitted so as not to distract the subject matter 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 ordinary or lexical meanings, and the inventor is appropriate as a concept of terms to describe his or her invention in the best way. It should be interpreted as a meaning and a concept consistent with the technical idea of the present invention based on the principle that it can be defined as such. Therefore, the configuration shown in the embodiments and drawings described in this specification is only a preferred embodiment of the present invention, and does not represent all of the technical spirit of the present invention, and various equivalents that can replace them at the time of this application It should be understood that there may be and variations.

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

According to the present invention, since one power transmitting end transmits power to the power receiving end through a single channel, it is possible to extend the life of the sensor device through power transmission through efficient scheduling in a network composed of multiple receiving ends.

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

The power transmitting end of FIG. 1 serves as a master, and the power receiving end serves as a slave.

The master and the slave may be configured in a structure that includes a T-TX/RX, a communication part for general communication, and a Power Transmitting Unit (PTU) or Power Receiving Unit (PRU).

The master and the slave commonly transmit and receive wireless data through T-TX/RX.

By performing Clear Channel Assessment (CCA) between multiple transmitting/receiving nodes, a wireless communication environment is configured so that data can be transmitted and received without collision in a corresponding frequency channel. In the process of CCA, Energy Detection or Channel Sensing for the corresponding frequency is performed to determine whether the channel is available or not. After the channel connection between the master slaves through the CCA is completed, the master can know the number and information of the slaves through wireless data communication in 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 to determine the position of the slave through RX, and then identifies the slave position and beamforms it from the Power Tx to the corresponding position to transmit power through the Power Channel for a certain period of time. To perform.

The slave may be composed of a plurality of array antennas, like a single antenna or a master, and includes a PRU that structurally serves to receive power. The PRU consists of a Power RX part for power reception and TX for transmitting a specific pattern signal through On-off Keying (OOK), and additionally includes a Master Beacon Receiver (MBR) that can acquire information from the Master Beacon. Can be. As a Master Beacon Receiver (MBR), it is possible to utilize envelop detectors that can be configured with simple circuits.

The MBR can perform TX Enabling by receiving and reading Amplitude-shift Keying (ASK) coded and transmitted master beacons (MB) by the master. As TX is enabled, a specific pattern signal can be generated to transmit the 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 terminal. It consists of DAC/LFP/MIXER/PA and multiple array antennas to beamform power to the receiving end of the transmitting end, and the transmitting end consists of LNA and down-mixer/LFP/ADC to receive power beacon from the receiving end. Consists of. Both the operation for calculating the position of the receiving end and the operation for performing beamforming are performed in the baseband of the transmitting end.

The receiver may consist of a rectifier receiving power, an MBR r to receive a master beacon received from a power channel, and a part to transmit a power beacon.

3 is a diagram showing a general MAC Superframe structure.

First, the existing Superframe (SF) is composed of a beacon, Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) section, and multiple 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 join request message 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 can transmit and receive data in the allocated D-Slot. Superframe repeats over time.

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

In general, in communication, a MAC layer requests a PHY layer to perform CCA in order to transmit and receive data without collision. Through the CCA process, energy detection or channel sensing is performed at the PHY stage, and whether or not the corresponding frequency channel is available or not is considered.

However, in a structure in which CCA is not used, separate scheduling is required for the PTU and the PRU to prevent collision when transmitting wireless power between the master and multiple slaves. For example, when the slave 1 and the slave 2 simultaneously transmit PBs for indicating their positions, a method for avoiding collision is needed. Therefore, the master needs to use a superframe structure for transmitting wireless power without collision with a specific slave by transmitting separate scheduling information such as assigning priority to the slave to multiple slaves in all directions.

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

Superframe consists of MB, PB, Channel Time Allocation (CTA) section. The network composed of one power transmitter and multiple power receivers has already completed the channel connection between the transmitter and the receiver by a wireless communication method such as Bluetooth or Wi-Fi. Through this, the power transmitter has the number of all power receivers connected to it. And the information of each power receiving end. Therefore, unlike the existing communication superframe, it shows 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 receiving end is additionally used.

The master can know information of slaves belonging to the same network through different wireless communication methods (Bluetooth, Wi-Fi, etc.). Slave information may include user authentication, device information, residual power, and the like.

The master schedules power transmission slot (P-slot) allocation to multiple slaves based on this information. The master transmits MBs in multiple directions to multiple slaves to transmit beacon information over a single channel. MB is Amplitude-shift Keying (ASK) coded and transmitted from one antenna to multiple slaves, and serves to synchronize the synchronization of slaves located in the same network as the master. In addition, it is possible to determine which slave is allocated to the P-Slot in the CTA section using the information included in the MB. MB frame may be composed of Preamble, Slave ID, Checksum, and the like.

After transmitting the MB of the PTU, slaves that have received 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 MB received by ASK coding as an MBR. The slave checks the Slave ID included in the MB through the MBR, and the corresponding slave can transmit the PB to the master using a signal such as OOK by TX Enabling from MBR to TX.

The transmitting end extracts a phase of a signal incident from each transmitting antenna using information included in the received PB, or uses a position recognition algorithm (such as a MUSIC algorithm) to determine the position of the receiving end to beamform power. After the PB transmission, in one Power Slot (P-Slot), which is a whole section of the CTA, the transmitting end can effectively transmit power by beamforming all antennas to the position of the corresponding receiving end calculated as phase information. As the master beamforms, the Signal-to-Noise Ratio (SNR) increases. The superframe is repeated with 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 showing the architecture of a wireless power transmission system according to the present invention.

The architecture of the wireless power transmission system is a one-to-many power transmission/reception structure, and may be composed of one power transmission end and multiple power reception ends. The power transmitting end is composed of a plurality of array antennas so that beamforming is possible, 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 receive an MB that is ASK-coded and transmitted through a single channel and include an MBR to determine the slave ID included in the MB. .

Figure 5(a) shows the transmission of MB performed at the start of CCA and Superframe, which are performed by different wireless communication methods for the connection of the wireless communication channel between the master and the slave. The master can know the number of slaves participating in the network and slave information by connecting the channel through the 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 the adjacent slaves including the slave ID in MB for allocation of a slave to receive power from the P-Slot in the CTA. One of the array antennas is used to transmit the MB in all directions.

Fig. 5(b) shows PB transmission and power transmission/reception occurring in P-Slot within CTA section of Superframe. In the RF wireless power transmission system, a total of two beacons are used, MB and PB. Slave receives ASK coded MB through MBR, which acts as an envelope detector, and reads information contained in MB to check whether it is a slave that can receive power from P-Slot. If you are a slave corresponding to the Slave ID of MB, MBR transmits TX Enabling to the TX of the PRU, so that the PB containing the phase information that the TX of the PRU can identify its location is transmitted to the master using a signal such as OOK. do. The master calculates the position by extracting the phase information of the slave from the PB received at the RX in the PTU, and beamforms the position with Power TX using an array antenna to intensively transmit power during the P-Slot corresponding to all sections of the CTA. Can be. The slave intensively receives power through the PRU's Power RX. At this time, all slots that are not allocated to slaves adjacent to slaves that intensively receive power are operating in the Rx mode, so weak power can be received.

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

One master and multiple slaves may exist in the network, and slaves receiving power from the P-Slot may vary according to the scheduling of the master. At the beginning, the PTU transmits MB in all directions at the very beginning of the Superframe for synchronization and allocation of slaves to receive power.

Multiple 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 can recognize the preamble that comes at the beginning of MB through the MBR, and then read the incoming slave ID and recognize that it must transmit the PB if it matches it. In the case of a slave allocated to a CTA section, power is requested by transmitting a PB from the PRU to the master for power charging. The transmitted PB includes phase information that can inform the location of the slave.

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

7 is a view showing the operation flow of the RF Control Protocol between the PTU and the PRU in the master and slave.

PTU and PRU sequentially perform configuration, beacon transmission, and RF WPT. Configuration is performed in the initial connection between the PTU and the PRU, and first, RF WPT Connection between the PTU and the PRU is performed. When RF WPT Connection is completed, set PRU Static Parameter, Station Probe Response, PRU Dynamic Parameter, and Station Dynamic Parameter to complete the configuration. Thereafter, the PTU transmits the PTU Beacon, which is the MB, in all directions to the adjacent slaves. 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 as described above, the PTU performs power transfer from the RF WPT to the corresponding PRU. Thus, the PRU can use the received power to charge the device's power. Subsequently, 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 transmission end composed of a plurality of array antennas and a plurality of power reception end nodes exist, and the power transmission end serves as a master, and the power reception end is a slave Performs the role of (slave).The master and the slave include T-TX/RX, which is a communication part for general communication, and the Power Transmitting Unit (PTU), and the Power Transmitting Unit (PTU) of the power transmitting end beamforms power. In order to allow multiple antennas to be individually phase-controlled, the power transmitting unit's Power Transmitting Unit (PTU) extracts the phase or phase difference received from the individual antennas, and based on this, determines the phase of each antenna. It includes a structure to form power to a specific location by controlling, and the power receiving terminal receives T-TX/RX, which is a communication part for general communication, and a part that converts a continuous beam (CW) into power and a power channel. It consists of a structure that includes a Power Receiving Unit (PRU) composed of MBR for receiving the Master Beacon and Part for transmitting the Power Beacon, and prior to transmitting power wirelessly, between the master and the slave through other wireless communication methods. It is a structure in which the channel connection is completed, and the system structure for dynamically scheduling the allocation of the receiving end to the channel resource for power transmission between one transmitting end and a plurality of receiving ends, and the MAC Superframe structure for the system, the proposed Superframe is largely a master beacon It consists of (MB), Power Beacon (PB), Channel Time Allocation (CTA) section, 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 be composed of a single Power Slot (P-Slot) for transmitting power by assigning it to a specific slave, and synchronizes between the slaves through the Master Beacon (MB). It informs whether Beacon TX is activated, and the power receiving end transmits a beacon (PB) indicating the location of the power receiving end to the power transmitting end when it is allocated to receive power by MB. It is a structure that can use the Master Beacon Receiver (MBR), which can receive and receive information from the transmitting end, as an envelope detector, and may have a structure that includes an envelope detector circuit in the power receiving end.

Features, structures, effects, and the like 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, and the like exemplified in each embodiment may be combined or modified for other embodiments by a person having ordinary knowledge in the field to which the embodiments belong. Therefore, 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 embodiments have been mainly described above, these are merely examples, and do not limit the present invention, and those skilled in the art to which the present invention pertains are exemplified above without departing from the essential characteristics of the present embodiment. It will be appreciated that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be implemented by modification. And differences related to these modifications and applications should be construed as being included in the scope of the invention defined in the appended claims.

Claims (1)

A plurality of power receiving terminals; And
And a power transmitting end transmitting phase to each of the plurality of power receiving ends by phase-controlling each of the plurality of array antennas.
Wireless power transmission system.

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