KR101863237B1 - Energy management method for transmitter in microwave power transfer system and energy management method for microwave power transfer system - Google Patents

Abstract

A power management method of a transmitter in a wireless power transmission system includes the steps of transmitting a microwave by a transmitter, receiving information on a power value and a stored power amount received from the receiver by the microwave, Determining a duration of transmitting the microwave in one frame and a strength of the microwave transmitted during the duration based on the amount of power and transmitting the microwave having the intensity at the active time of the receiver to the transmitter during the duration .

Description

TECHNICAL FIELD [0001] The present invention relates to a power management method for a transmitter in a wireless power transmission system and a power management method in a wireless power transmission system. [0002]

The techniques described below relate to techniques for managing power in a wireless power transmission system.

Microwave wireless power transmission technology can transmit power to a receiving end that is farther than a wireless power transmission technique such as magnetic induction and magnetic resonance. Current long-range wireless power transmission can be useful for remotely charging low-power sensor nodes constituting the IoT sensor network since the power reaching the receiving end is relatively small.

U.S. Published Patent Application No. US2007 / 0021140

The technology for the conventional sensor network was mainly to optimize the activity period of the sensor node. The technique described below is intended to provide a management technique for controlling the activity period of the transmitting end and the transmission power of the transmitting end in the wireless power transmission system and controlling the activity period of the receiving end.

A power management method of a transmitter in a wireless power transmission system includes the steps of transmitting a microwave by a transmitter, receiving information on a power value and a stored power amount received from the receiver by the microwave, Determining a duration of transmitting the microwave in one frame and a strength of the microwave transmitted during the duration based on the amount of power and transmitting the microwave having the intensity at the active time of the receiver to the transmitter during the duration .

A method for power management in a wireless power transmission system includes transmitting a beacon packet over a data communication channel by a transmitter, transitioning the receiver that received the beacon packet from an inactive state to an active state, The method of claim 1, further comprising: transmitting a microwave for power transmission in a frame; collecting power using the microwave received by the receiver in the active state; Determining the duration of the microwave transmission in the power transmission frame and the intensity of the microwave transmitted during the duration based on the power value and the power amount, The microwave having the intensity For a duration of time.

The technique described below basically supplies power wirelessly to minimize the energy consumed by the transmitter while allowing the receiver to operate stably.

1 is an example of a block diagram for a wireless power transmission system.
Figure 2 is an example of a protocol for power management.
Figure 3 is an example of the process by which a wireless power transmission system operates.
4 is an example of a process 300 in which the wireless power transmission system performs power management.

The following description is intended to illustrate and describe specific embodiments in the drawings, since various changes may be made and the embodiments may have various embodiments. However, it should be understood that the following description does not limit the specific embodiments, but includes all changes, equivalents, and alternatives falling within the spirit and scope of the following description.

The terms first, second, A, B, etc., may be used to describe various components, but the components are not limited by the terms, but may be used to distinguish one component from another . For example, without departing from the scope of the following description, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

As used herein, the singular " include " should be understood to include a plurality of representations unless the context clearly dictates otherwise, and the terms " comprises & , Parts or combinations thereof, and does not preclude the presence or addition of one or more other features, integers, steps, components, components, or combinations thereof.

Before describing the drawings in detail, it is to be clarified that the division of constituent parts in this specification is merely a division by main functions of each constituent part. That is, two or more constituent parts to be described below may be combined into one constituent part, or one constituent part may be divided into two or more functions according to functions that are more subdivided. In addition, each of the constituent units described below may additionally perform some or all of the functions of other constituent units in addition to the main functions of the constituent units themselves, and that some of the main functions, And may be carried out in a dedicated manner.

Also, in performing a method or an operation method, each of the processes constituting the method may take place differently from the stated order unless clearly specified in the context. That is, each process may occur in the same order as described, may be performed substantially concurrently, or may be performed in the opposite order.

The techniques described below relate to techniques for transmitting microwaves (RF signals) to transmit power. The techniques described below relate to a scheme for efficiently delivering power in a wireless power transmission system. The techniques described below relate to techniques for controlling the operation of the transmitting and receiving ends of a wireless power transmission system.

1 is an example of a block diagram for a wireless power transmission system. The system of FIG. 1 mainly includes a transmitter 100 that transmits a microwave and a receiver 200 that receives power received by the microwave. 1, the transmitter 100 may correspond to a power beacon and the receiver 200 may correspond to a sensor node in a system that supplies power to a sensor node using an RF signal. Furthermore, the transmitter 100 may be a Wi-Fi AP, a mobile communication base station, or a dedicated device for power supply. The receiver 100 may be an IoT device, a smart device, a wearable device, an automobile, or the like, which receives electric power using the received microwave.

The transmitter 100 includes a DC power supply 110, a signal generator 120, an amplifier 130, an antenna 140, a controller 150, a first RF transceiver RF Transceiver, 160). Although the first RF transceiver 160 uses a separate antenna for data communication, the first RF transceiver 160 does not have a reference numeral in FIG.

The operation of the transmitter 100 will be briefly described. The DC power supply 110 supplies power for transmitting microwaves. The signal generator 120 generates CW (Continuous Waveform) microwave. The amplifier 130 amplifies the microwave generated by the signal generator and transmits the amplified microwave to the antenna 140. The intensity of the transmitted signal varies depending on the degree to which the amplifier 130 amplifies the microwave. The controller 150 delivers a signal to the amplifier 130 that controls the degree to which the amplifier 130 amplifies the microwave. The first RF transceiver 160 performs data communication with the receiver 200. The first RF transceiver 160 receives the received power measurement and the residual power from the receiver 200.

The microwave amplified by the amplifier 130 and transmitted to the antenna 140 and the data transmitted / received by the first RF transceiver 160 may use different channels. The wireless power transmission system can use a dedicated channel for data communication and a dedicated channel for transmitting power.

The receiver 200 includes an antenna 210, a wireless energy harvester 220, an energy storage 230, a power sensor 240, an MCU (Microcontroller) 250, a second RF transceiver (260).

The operation of the receiver 200 will be briefly described. The antenna 210 receives the microwave transmitted by the transmitter 100. The wireless energy collector 220 is a device for converting the received microwave into a DC current. The wireless energy collector 220 may include a rectifier for converting the RF signal into a constant DC current and a DC-DC converter for converting the DC current converted by the rectifier into a DC current at a predetermined level to be used in the receiver 200, and the like.

The wireless energy collector 220 may power the collected power to active devices, such as the MCU 260 and the second RF transceiver 280. Further, the wireless energy collector 220 may transmit the residual power to the energy store 230. The energy storage 230 is a device that stores power such as a supercapacitor or a battery. 1 shows that the power stored in the energy storage 230 is supplied by the active device.

The power sensor 240 can measure the power value of the received signal using the signal output from the wireless energy collector 220. The power sensor 240 can measure a certain level of power value using an analog-to-digital converter (ADC). The power sensor 240 can measure the voltage of the signal that the energy store 230 supplies to other active elements (sensor, MCU, etc.) of the receiver 200 to measure the amount of power held by the energy store 230 have. The amount of power held by the energy storage 230 is hereinafter referred to as the remaining amount of power. The MCU 250 is a device for controlling the operation of the receiver 200. The second RF transceiver 260 transmits the received power value and the residual power amount measured by the power sensor 240 to the transmitter 100 through data communication.

The first RF transceiver 160 and the second RF transceiver 260 use the same type of communication scheme for data communication. For example, the first RF transceiver 160 and the second RF transceiver 260 may use a communication method such as mobile communication, IEEE 802.11, IEEE 802.15.4, and Bluetooth low energy (BLE).

는

와 같다.Figure 2 is an example of a protocol for power management. The energy management protocol operates on a frame having a certain temporal length. The transmitter 100 transmits microwaves in units of a plurality of frames having a predetermined length according to the passage of time. One frame is T _frame in length. FIG. 2 shows five frames as an example. 2 shows a section in which a transmitter 100 transmits microwave for power transmission in one frame in a shaded manner. The section for transmitting the microwave in one frame is from the beginning of the frame to a certain point in time. The length of the section for transmitting microwaves is denoted by T _ET . The ratio of the interval in which the microwave is transmitted in one frame is referred to as a duty cycle in the transmitter 100. Duty cycle

The

.

The controller 150 of the transmitter 100 performs duty cycle adjustment or transmission power adjustment. However, for convenience of explanation, it is explained that the transmitter 100 determines and controls a specific factor.

The transmitter 100 may adjust the duty cycle of the transmitter. The transmitter 100 performs duty cycling in which microwaves are transmitted only for a predetermined time period for each frame. For this, the transmitter 100 starts transmitting microwaves at the beginning of each frame, stops microwave transmission after a predetermined time, and resumes microwave transmission at the beginning of the next frame. That is, the transmitter 100 may adaptively adjust the duty cycle every frame. When the DC power supply 110 of the transmitter 100 supplies power to the amplifier 130 and the DC power supply 110 stops supplying power to the amplifier 130, do. The transmitter 100 may additionally adjust the transmit power of the microwave every frame.

The transmitter 100 may transmit a beacon packet using the first RF transceiver 160 at the start of each frame for temporal synchronization with the receiver 200. [ As will be described later, a beacon packet may convey not only synchronization but also information for controlling the sensor node.

The receiver 200 may have a data reception state Rx, an active state, a data transmission state Tx, and an inactive state Idle. At the beginning of each frame, the receiver 200 enters the data reception state (Rx) and receives a beacon packet. When the beacon packet is received, the receiver 200 switches the second RF transceiver 260 to the low power state and enters the active state where only the MCU operates, thereby reducing energy consumption.

In the active state (Active), the receiver 200 may measure the received power value received from the transmitter 100 and the amount of energy stored in the energy store 230. Also, in the active state (Active), the receiver 200 can perform an operation specific to the receiver. For example, if the receiver 200 is a sensor node, it may sense specific information.

In the active state (Active), the receiver 200 prepares a report packet (Report Packet) to be transmitted to the transmitter 100. The report packet may include received power value, amount of residual energy, various sensing information, and the like. After the activation state is terminated, the receiver 200 activates the second RF transceiver 260 to enter the transmission state (Tx) and transmit the report packet. On the other hand, after the transmission state is ended, the receiver 200 enters the inactive state (Idle) and can save the energy as much as possible.

On the other hand, one receiver 200 can wake up at a constant frame interval without waking up every frame for energy saving. The period in which the receiver 200 wakes up is referred to as an activity period. If the receiver 200 wakes up from a specific frame and then enters a disabled state, the receiver 200 can wake up again after a frame as long as the activity period. Energy consumption in the inactive state is very small, so that the energy consumption of the receiver 200 can be greatly reduced by this method. Fig. 2 shows an example in which the activity period is two frames.

As will be described later, the transmitter 100 may determine the activity period of the receiver 200 in consideration of the received power value and the remaining power amount, and may transmit the determined activity period to the receiver 200. [ For example, the transmitter 100 may transmit an activity period to the receiver 200 in a beacon packet. The receiver 200 operates by setting an activity period according to information on the activity period included in the beacon packet. Alternatively, the receiver 200 may determine the activity period itself in consideration of the received power value and the residual power amount. In this case, the receiver 200 should inform the transmitter 100 of the activity period determined by the receiver 200 through a report packet or the like.

Figure 3 is an example of the process by which a wireless power transmission system operates. FIG. 3 is an example in which the wireless power transmission system of FIG. 1 determines a power management scheme for microwave power transmission. One frame is used as a reference. The transmitter 100 transmits a microwave for power transmission (1). The receiver 200 determines the received power measurement value and the remaining power amount of the received microwave and transmits it to the transmitter 100 (2). The transmitter 100 may determine at least one of its duty cycle, the intensity of the microwave to be transmitted, and the activity period of the receiver in consideration of the received power measurement value and the remaining power amount. The transmitter 100 transmits the microwave according to the determined duty cycle and the intensity of the signal (4).

The process by which the transmitter 100 determines the power management scheme will be described in more detail. The transmitter 100 largely determines the power management scheme in consideration of three goals. First, the power value used by the transmitter 100 is minimized. Second, it guarantees the minimum energy E _min that the receiver 200 can operate. That is, the remaining power amount E of the receiver 200 is equal to or greater than E _min . Third, the transmitter 100 may design a scheme so that the applications of the receiver 200 can receive the report packets as many times as required. There are conflicts between these three goals. Therefore, the transmitter 100 desirably designs the scheme so that the three goals can be optimized.

), (ii) 송신 전력의 세기(

) 및 (iii) 수신기(110)의 활동 주기(

)이다. 듀티 사이클은

범위 값을 갖는다.

은 송신기(100)가 하나의 프레임에서 마이크로파를 전송해야하는 비율의 하한값이다. 송신 전력의 세기는

범위를 갖는다.

는 송신기(100)가 송신할 수 있는 최대 전력값이다. The transmitter 100 designs a power management scheme considering three parameters. The three parameters are (i) the above-mentioned duty cycle (

), (ii) the intensity of the transmission power (

) And (iii) the activity period of the receiver 110 (

)to be. The duty cycle is

Lt; / RTI >

Is the lower limit of the rate at which the transmitter 100 must transmit microwaves in one frame. The strength of the transmission power is

Lt; / RTI >

Is the maximum power value that the transmitter 100 can transmit.

, 송신 전력의 세기를

, 수신기(200)의 활동주기를

라고 하자. 송신기(100)는 이들 변수의 결정을 위해 수신기(200)가 보고한 수신 전력값

과 잔여 전력량

을 활용한다. 에너지 관리 프로토콜은 잔여 전력량

을 목표잔여에너지양 이상으로 유지하면서 파워비콘에서 소모되는 DC전력의 양을 최소화하는 것이다. 또한 에너지관리프로토콜은 활동주기를 최소한 목표활동주기

으로 유지하고자 한다. 아래 표 1은 송신기(100)가 전력 관리 스킴을 결정하는 알고리즘에 대한 예이다.The duty cycle of the i-th frame is

, The strength of the transmission power

, The activity cycle of the receiver 200

Let's say. The transmitter 100 determines the received power value reported by the receiver 200 for determination of these variables

And residual power

. The energy management protocol uses the residual power

Is maintained above the target residual energy amount while minimizing the amount of DC power consumed in the power beacon. The energy management protocol also requires that the activity cycle be at least the target activity period

. Table 1 below is an example of an algorithm in which the transmitter 100 determines a power management scheme.

,

,

는 각각 스텝 사이즈를 의미한다. 상기 알고리즘을 간략하게 설명한다. 알고리즘은 우선적으로 잔여 전력량

를 목표 잔여 전력량

이상으로 유지하고자한다. 상기 조건이 만족하는 경우 알고리즘은 활동주기

를 목표 활동주기

로 유지한다. 이러한 두 가지 조건이 만족하는 경우에만 송신기(100)는 자신이 소모하는 전력을 최소화하게 된다.In the algorithm

,

,

Respectively denote step sizes. The above algorithm will be briefly described. The algorithm first determines the residual power

The target residual power amount

Or more. If the above condition is satisfied,

To the target activity cycle

. Only when these two conditions are satisfied, the transmitter 100 minimizes the power consumed by the transmitter 100 itself.

가 1보다 작은 경우 송신전력

을 조절하여 최적의 효율을 나타내는 수신 전력값인

만큼의 수신전력을 수신기(200)가 얻을 수 있도록 한다. 또한 동시에

을 조절하여 수신기(200)의 잔여 전력량을

로 유지시킨다. (1) The algorithm uses the duty cycle

Is less than 1, the transmit power

And the received power value indicating the optimum efficiency

So that the receiver 200 can obtain the received power as much as possible. At the same time

To adjust the remaining power amount of the receiver 200

.

가 1이고 송신전력

가 최대 송신전력

보다 작은 경우에는

를 조절하여 잔여 전력량을

으로 유지시킨다. (2)

Is 1 and the transmission power

The maximum transmit power

If it is smaller

To adjust the remaining power

.

가 1이고 송신전력

가 최대 송신전력

에 도달한 경우에는 활동주기

를 조절하여 센서노드의 잔여 전력량을

으로 유지시킨다. (3) The algorithm uses the duty cycle

Is 1 and the transmission power

The maximum transmit power

, The activity cycle

To adjust the residual power amount of the sensor node

.

4 is an example of a process 300 in which the wireless power transmission system performs power management. The transmitter 100 may supply power to a plurality of receivers. Figure 4 is an example of the process by which the transmitter 100 generates a power management scheme to power two receivers 200A and 200B. Referring to FIG. 2, frames 1 and 3 are periods during which the receiver 200A operates, and frames 2 and 4 correspond to periods during which the receiver 200B operates.

Receiver 200A is currently inactive (310). Transmitter 100 transmits 302 a beacon packet and the receiver transitions its state to an active state (303). The transmitter 100 transmits a microwave for power supply (304). The receiver 200A performs an operation in an active state (305). For example, the receiver 200A collects power with the received microwave, and calculates a received power value and its remaining power amount. The receiver 200A transmits a report packet including the received power value and the residual power amount (306). The receiver 200A then turns its state into an inactive state (307).

The transmitter 100 then generates the power management scheme described above based on the information transmitted by the receiver 200A in frame 1. In FIG. 4, the transmitter 100 determines the duty cycle and transmit power intensity for the receiver 200A in the frame 2 period (321).

Transmitter 100 performs the same operation as frame 1 in frame 2 for receiver 200B. Receiver 200B is inactive (311). Transmitter 100 transmits a beacon packet (312) and the receiver transitions its state to an active state (313). The transmitter 100 transmits a microwave for power supply (314). The receiver 200B performs an operation in an active state (315). For example, the receiver 200B collects power with the received microwave, and calculates a received power value and its remaining power amount. The receiver 200B transmits a report packet including the received power value and the residual power amount (316). The receiver 200B then switches its state to the inactive state (317).

The transmitter 100 then generates the power management scheme described above based on the information transmitted by the receiver 200B in frame 2. [ In FIG. 4, it is shown that the transmitter 100 determines the duty cycle and the transmit power intensity for the receiver 200B in the frame 3 interval (341).

Transmitter 100 transmits (331) a beacon packet at frame 3 and the receiver switches its state to an active state (332). The transmitter 100 transmits a microwave for power supply (333). At this time, the transmitter 100 transmits the microwave according to the duty cycle and the transmission power determined in the step 321.

The receiver 200A performs an operation in an active state (334). The receiver 200A transmits a report packet including the received power value and the residual power amount (335). The receiver 200A then switches its state to the inactive state (336).

The transmitter 100 repeats the procedure of FIG. 4 for each receiver every frame.

The present embodiment and drawings attached hereto are only a part of the technical idea included in the above-described technology, and it is easy for a person skilled in the art to easily understand the technical idea included in the description of the above- It will be appreciated that variations that may be deduced and specific embodiments are included within the scope of the foregoing description.

100: Transmitter
110: DC power supply
120: Signal generator
130: Amplifier
140: antenna
150:
160: first RF transceiver
200: receiver
210: antenna
220: Wireless energy collector
230: Energy storage
240: Power sensor
250: MCU
260: second RF transceiver

Claims (15)

Transmitting a microwave to a receiver;
Receiving information on the power value received by the transmitter by the microwave and the amount of power stored in the receiver from the receiver;
Determining the duration of the microwave transmission in one frame and the intensity of the microwave transmitted during the duration based on the power value and the power amount of the transmitter; And
The transmitter transmitting microwave having the intensity at the active time of the receiver for the duration,
Wherein the transmitter determines the duration and the intensity such that the interval between activity times of the receiver maintains a constant reference value and the energy consumed by the transmitter is minimized while the receiver has power above a reference value, A method for power management of a transmitter in a system. The method according to claim 1,
Wherein the transmitter determines the duration and the strength so that the energy consumed by the transmitter is minimized while the receiver holds power above a reference value. The method according to claim 1,
Wherein the transmitter receives the power value and the amount of power from a plurality of receivers and determines a duration and microwave intensity to transmit the microwave for each receiver. The method according to claim 1,
Wherein the transmitter determines the duration and the strength by further considering an activity period of the receiver. The method according to claim 1,
Wherein the receiver has an activity period for collecting power and the transmitter further comprises determining an activity period of the receiver based on the duration and the strength. delete The method according to claim 1,
Wherein the transmitter adjusts at least one of the duration and the strength if the duration is less than the length of the frame. The method according to claim 1,
Wherein the transmitter adjusts the strength if the duration equals the length of the frame and the strength is less than a maximum value that the transmitter can transmit. The method according to claim 1,
Wherein the transmitter adjusts the interval of the activity time if the duration is equal to the length of the frame and the intensity is equal to a maximum value that the transmitter can transmit. 10. The method of claim 9,
Wherein the transmitter transmits the adjusted interval of activity time to the receiver. Transmitting a beacon packet over a data communication channel by a transmitter;
Switching a receiver that has received the beacon packet from an inactive state to an active state;
The transmitter transmitting a microwave for power transmission in one power transmission frame;
Collecting power using the microwave received by the receiver in the active state, and transmitting information on the power value received by the microwave and the amount of power stored in the receiver to the transmitter through the data communication channel;
Determining the duration of the microwave transmission in the power transmission frame and the intensity of the microwave transmitted during the duration based on the power value and the power amount; And
The transmitter transmitting microwaves having the intensity in another power transmission frame for the duration,
The transmitter maintains at least one of the duration, the strength and the interval so that the interval between the active times of the receiver maintains a constant reference value and the energy consumed by the transmitter is at least the receiver holding the power above the reference value Wherein the power management method is a power management method in a wireless power transmission system. 12. The method of claim 11,
Wherein the transmitter determines the duration and the strength so that the energy consumed by the transmitter is minimized while the receiver holds power above a reference value. 12. The method of claim 11,
Wherein the transmitter further comprises determining an activity period of the receiver based on the duration and the strength, and the receiver receiving the beacon packet including the activity period transmits a wireless power transmission Method for power management in a system. 12. The method of claim 11,
Wherein the transmitter transmits the duration and the strength to the receiver and the receiver further comprises determining an activity period of the receiver based on the duration and the strength, . delete

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