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CN110881195B - Method and system for multi-frequency multi-target selective wireless energy transmission - Google Patents

Method and system for multi-frequency multi-target selective wireless energy transmission Download PDF

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CN110881195B
CN110881195B CN201910789365.XA CN201910789365A CN110881195B CN 110881195 B CN110881195 B CN 110881195B CN 201910789365 A CN201910789365 A CN 201910789365A CN 110881195 B CN110881195 B CN 110881195B
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钟成
赵德双
刘要红
包金龙
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University of Electronic Science and Technology of China
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Abstract

The invention discloses a multi-frequency multi-target selective wireless energy transmission method and system, and belongs to the technical field of electromagnetic wave wireless energy transmission. The method comprises the following steps: constructing a receiving device group and a transmitting device group of a multi-frequency energy transmission system; discretizing the energy transmission bandwidth range adopted by the system according to the measured maximum multipath time delay in the energy transmission environment, and extracting the energy transmission channel parameters of the energy transmission system at each frequency point; selecting an optimal energy transmission frequency point according to the extracted energy transmission channel parameters and a calculation formula; and determining the optimal feed-in signal corresponding to the selected frequency point by using an optimization algorithm to realize multi-target selective parallel energy transmission. The invention solves the problem that the existing multi-target selective energy transmission technical method is difficult to give consideration to energy transmission efficiency and side lobe values, and realizes high-efficiency and low-side-lobe multi-target selective parallel energy transmission.

Description

Multi-frequency multi-target selective wireless energy transmission method and system
Technical Field
The invention belongs to the technical field of electromagnetic wave wireless energy transmission, and particularly relates to a multi-frequency multi-target selective energy transmission method and system.
Background
Wireless Power Transfer (WPT) is a leading research edge in the current energy transmission field, and is also a research hotspot which is concerned by the scientific and industrial fields in recent years. Compared with wired energy transmission, the WPT can completely get rid of the constraint of a power transmission cable, can supply energy to electronic equipment uninterruptedly, conveniently, flexibly and anytime anywhere in all weather, is a revolutionary energy transmission technology, can be widely applied to various fields in national economy, and has scientific research significance and application value inferior to the current wireless communication technology.
At present, a large number of wireless energy transmission methods mainly aim at single-target energy transmission and are difficult to meet the application requirements of a plurality of devices to be transmitted in an energy transmission environment. In recent years, in order to solve the problem of multi-target parallel energy transmission, researchers have proposed a new Wireless energy transmission technology, namely "Time Reversal Wireless Power Transfer (TR-WPT)". Different from the traditional WPT, the TR-WPT has the space-time focusing characteristic, and electromagnetic energy radiated by an antenna is accurately conveyed to a target point in a 'point focusing wave' mode. TR-WPT is expected to realize multi-target selective parallel energy output by means of the unique energy output mechanism.
In recent years, many researchers have proposed different approaches to multi-objective parallel wireless energy delivery. An invention patent with patent application number CN201810698828.7 discloses a method for parallel energy transmission of multiple energy receiving targets by using a single transmitting device using multi-frequency signals, but this method cannot realize multi-target selective energy transmission, and a single transmitting antenna transmits energy by radiating to the periphery, most of the energy is dissipated in space, and the overall energy transmission efficiency is low. An invention patent with patent application number CN201810580750.9 discloses a method for realizing multi-target selective wireless energy transmission by using single-frequency signals, but when the method transmits energy to a plurality of targets to be transmitted selected from some multi-targets, the energy transmission efficiency is low, and large side lobes are generated at the same time. The invention patent with the application patent number of CN201810580731.6 discloses a method for realizing selective energy transmission of a plurality of transmitting devices to a plurality of energy receiving targets by adopting a frequency division multiple access mode, which utilizes different frequency signals to carry out energy transmission on different energy receiving targets and can realize independent energy transmission of each target in multiple targets, so that when a plurality of selected targets are subjected to parallel energy transmission, side lobes hardly occur, each energy receiving antenna can only receive appointed single frequency energy, and the energy of other frequency points at the position of the energy receiving antenna is greatly wasted, so that the energy transmission efficiency of the multiple targets is reduced.
In summary, the existing multi-target selective wireless energy transmission method has some inherent defects, and it is difficult to consider both low side lobe and high energy transmission efficiency under the condition of any multi-target selective energy transmission.
Disclosure of Invention
In order to overcome the inherent defects of the conventional multi-target selective wireless energy transmission method, the invention provides a multi-frequency multi-target selective energy transmission method and a system, which specifically comprise the following steps:
step 1, selecting energy transmission frequency points of a multi-frequency energy transmission system
Step 1-1. construction of energy transmission system
Placing M receiving devices EC in the target energy transmission area1～ECMThe set of receiving devices ECG constituting the energy delivery system.
N transmitting devices TR are arranged around the outside of the energy transmission area1～TRNAnd forming a transmitting device set TRM of the energy transmission system.
Step 1-2, extracting channel parameters of the energy transmission system
The energy transmission system constructed based on the step 1-1 detects the maximum multipath time delay tau in the energy transmission systemmaxThereby obtaining a corresponding coherence bandwidth of
Figure RE-GDA0002361348840000021
In order to ensure that the energy transmission channels between two arbitrarily selected frequency points do not belong to the same flat fading channel, the energy transmission bandwidth range [ f ] adopted by the system is divided into 2 delta B frequency intervalsL,fH]Discretizing to obtain K frequency points f1,…fk,…fK，1≤k≤K。
Extracting system energy transmission channel parameters under the K different frequency points, and specifically operating the following steps:
(1) will have a frequency f1By receiving means EC1～ECMTransmitting, N transmitting means TR1～TRNReceiving and recording the sinusoidal signal, i.e. M groups of frequencies f in total1Is expressed as H1＝[h11,...hm1,...hM1]T∈CM×NWherein h ism1Denotes the m-th receiving device ECmWith N transmitting means TR1～TRNHas a frequency of f1M is more than or equal to 1 and less than or equal to M, superscript T represents matrix transposition, CM×NA complex matrix representing M N;
(2) in addition, the frequency is selected to be f2,…fk,…fKSequentially repeating the above operations to extract f2,…fk,…fKLower sinusoidal signal channel parameter matrix H2，…Hk,…HK。
Step 1-3. selection of frequency point of energy transmission system
Selecting all receiving devices EC in the energy transmission area1～ECMThe total efficiency of energy output of the M energy output targets represents the total efficiency of the whole energy output area.
Under K different energy transmission frequency points, the energy transmission efficiency of all receiving devices is calculated by a formula
Figure RE-GDA0002361348840000031
To solve, wherein etakK is more than or equal to 1 and less than or equal to K and lambda represents the energy transmission efficiency under the K frequency pointmax(. cndot.) represents the maximum eigenvalue of the matrix,
Figure RE-GDA0002361348840000032
represents the channel matrix HkThe conjugate transpose of (c).
The method comprises the following specific operation steps:
(1) utilizing the sine signal channel parameter matrix H extracted in the step 1-21,…,HKIn combination with the formula
Figure RE-GDA0002361348840000033
Calculating the matrix under K different frequencies
Figure RE-GDA0002361348840000034
Maximum eigenvalue of
Figure RE-GDA0002361348840000035
(2) Sequentially arranging the K maximum characteristic values according to the size sequence, and selecting A maximum values
Figure RE-GDA0002361348840000036
Figure RE-GDA0002361348840000036
1≤ka≤kANot more than K, and the corresponding frequency points are respectively
Figure RE-GDA0002361348840000037
Then the a frequency points are the energy transmission frequency points selected by the energy transmission system.
It should be noted that the larger the value a is, the more the selected energy transmission frequency points are, which may make the energy transmission effect of the system better, but at the same time, the size, cost and implementation difficulty of the energy transmission system may also be increased, so that the selection of the actual number of frequency points must take into account the actual energy transmission requirement and the complexity and cost of the energy transmission system.
Step 2, realizing multi-target selective wireless energy transmission
Step 2-1, setting system optimization variables and optimization indexes
E receiving devices needing energy transmission are selected according to actual application requirements
Figure RE-GDA0002361348840000038
The rest M-E receiving devices are used as the targets to be transmitted
Figure RE-GDA0002361348840000039
Namely the non-energy-to-be-transmitted target.
The system optimization variables are set as follows:
setting the weighting factors under the selected A different energy transmission frequency points as
Figure RE-GDA00023613488400000310
Wherein
Figure RE-GDA0002361348840000041
Figure RE-GDA0002361348840000042
Is expressed in frequency
Figure RE-GDA0002361348840000043
Weighting factor of the next mth receiving device, if ECmBelong to E targets to be transported
Figure RE-GDA0002361348840000044
For complex variables containing magnitude-phase information, if ECmBelong to M-E non-energy-transmission targets, then
Figure RE-GDA0002361348840000045
The system optimization index is set as follows
(1) M-E non-energy-transmission target positions
Figure RE-GDA0002361348840000046
Received maximum power value and E targets to be transmitted
Figure RE-GDA0002361348840000047
The ratio of the minimum received power value is defined as a side lobe value SLL of the multi-frequency energy transmission system;
(2) e targets to be transported
Figure RE-GDA0002361348840000048
Total received power and N transmitting devices TR1～TRNThe ratio of the total emitted power is defined as the efficiency value eta of the multi-frequency energy transmission system;
(3) in order to take two energy output indexes of the system into consideration, a maximum efficiency threshold eta is setthAnd a minimum side lobe threshold SLLthAnd expressing the joint optimization indexes of the two by using a COST function COST: COST ═ w1·(SLL-SLLth)+w2·(ηth-η)，w1、w2Represents the optimal weight coefficient between SLL and η.
Step 2-2. optimization of system feed-in signal
In practical application, according to actual demand, setting power distribution ratio w 'between E energy targets to be transmitted as [ w'1,w'2,…,w'E]I.e. satisfy
Figure RE-GDA0002361348840000049
Wherein
Figure RE-GDA00023613488400000410
Representing E targets to be energy-delivered
Figure RE-GDA00023613488400000411
Respectively receiving the energy of the multi-frequency signal. In order to obtain the optimal feed-in signal under A energy transmission frequency points of the system, a weighting factor is used as an optimization variable, and the two indexes of a side lobe value SLL and energy transmission efficiency eta of the system are jointly optimized, wherein the specific optimization problem can be represented as follows:
Figure RE-GDA00023613488400000412
Figure RE-GDA00023613488400000413
for solving the problem, a global optimization algorithm (such as simplex algorithm, genetic algorithm and ant colony algorithm) can be adopted to obtain a series of optimal weighting factors which minimize COST
Figure RE-GDA0002361348840000051
The feed-in signal under A energy transmission frequency points can be obtained as
Figure RE-GDA0002361348840000052
Wherein
Figure RE-GDA0002361348840000053
Figure RE-GDA0002361348840000053
1≤ka≤kA≤K。
Step 2-3. transmission of system feed-in signal
The feed-in signals of all frequency points are obtained through the optimization
Figure RE-GDA0002361348840000054
Superimposed to form an aggregate feed signal
Figure RE-GDA0002361348840000055
The total feed-in signals are respectively fed into the corresponding N transmitting devices TR1～TRNAnd in the middle, the high-efficiency and low-sidelobe energy transmission can be realized for the expected E energy targets to be transmitted.
The invention has the beneficial effects that:
(1) the method can realize wireless energy transmission with high efficiency and low side lobe under the condition of arbitrary multi-target selective energy transmission;
(2) the invention can select the energy transmission frequency of the system according to the specific energy transmission scene to achieve the optimal energy transmission effect;
(3) the invention realizes the free selection of the frequency of the energy transmission system, and can avoid the conflict between the energy transmission frequency and the existing communication frequency in the energy transmission environment;
(4) the invention realizes that the receiving power among a plurality of targets to be transmitted is in any proportion;
(5) the invention can realize multi-target selective wireless energy transmission according to the practical application requirements and different emphasis on energy transmission efficiency and side lobe values.
Drawings
Fig. 1 is a schematic structural diagram of a multi-frequency wireless energy transmission system;
fig. 2 is a block diagram of a receiving device set of the multi-frequency wireless energy transmission system;
fig. 3 is a block diagram of a transmitting device set of the multi-frequency wireless energy transmission system;
the metal reverberation cavity model employed in the example of fig. 4;
FIG. 5 is a block diagram of a receiver block architecture employed in the example;
FIG. 6 is a block diagram of a transmit bank architecture employed in the example;
pair EC in the example of FIG. 74,EC5,EC6A field distribution pattern of energy transfer;
FIG. 8(a) is a graph comparing the side lobe values of multi-frequency and single-frequency energy transmission in the example;
FIG. 8(b) is a graph of efficiency comparison of multi-frequency versus single-frequency power delivery in the example;
FIG. 8(c) is a graph of COST values for multiple frequency versus single frequency energy delivery in the example.
Detailed Description
The invention is further described below with reference to the figures and examples.
The present embodiment provides a multi-frequency multi-target selective energy transmission method and system, the structural diagram of the system is shown in fig. 1, where 1 represents the receiving device group ECG, 2 is the selected non-energy transmission device, 3 is the selected energy transmission device, and 4 is the transmitting device TR2～TRNAnd 5 is a transmitting device set TRM.
The structure of the receiving device group is shown in fig. 2, and includes: energy-receiving antenna AR1～ARMFor transmitting a sinusoidal detection signal and receiving an energy transmission signal; signal source OSC1～OSCMFor generating a probe signal of a selected frequency; LOAD1～LOADMThe device load which needs to be supplied with power is driven by direct current; rectifier PRU1～PRUMFor coupling a receiving device EC1～ECMThe received multi-frequency sinusoidal energy transmission signal is converted into direct current energy and is provided to a LOAD LOAD1～LOADM(ii) a Switch S1～SMFor switching the powered antenna AR1～ARMAnd a signal source OSC1～OSCMOr rectifying means PRU1～PRUMTo be connected to each other. The connection relationship is as follows: energy-receiving antenna AR1～ARMBy means of a switch S1～SMRespectively connected with signal source OSC1～OSCMAnd a rectifying unit PRU1～PRUMPRU connecting and rectifying device1～PRUMRear end connected with LOAD1～LOADM。
The structure of the transmitting device set is shown in fig. 3, and includes: energy transmission antenna AT1～ATNFor receiving a probing signal and transmitting an energy transmission signal; band-pass filter BPF1～BPFNFor filtering outL,fH]Clutter outside of bandwidth; waveform detection module WDM1～WDMNThe device is used for recording the waveform of the detection signal transmitted by the receiving device group; combinerSUM1～SUMNRespectively at a frequency of
Figure RE-GDA0002361348840000061
Synthesizing a multi-tone signal by the plurality of sinusoidal energy transmission signals; microwave power source OSC _ F1～OSC_FARespectively for generating a frequency of
Figure RE-GDA0002361348840000062
The sine energy transmission signal; power divider PD _ F1～PD_FAN equal power dividers are respectively used for connecting the microwave power source OSC _ F1～OSC_FAThe generated sinusoidal signals are divided into N paths with equal power, and the amplitude and the phase of the signals are the same; adjustable power amplifier PA1_F1～PAN_F1,…,PA1_FA～PAN_FARespectively for adjusting each channel frequency to
Figure RE-GDA0002361348840000071
The single tone energy transmission signal amplitude of (a); phase shifter PS1_F1～PS16_F1,…,PS1_FA～PS16_FAFor adjusting the frequency to
Figure RE-GDA0002361348840000072
The single-tone energy transmission signal phase; switch R1～RNFor switching band-pass filters BPF1～BPFNWDM with waveform detection module1～WDMNOr combiner SUM1～SUMNThe connection of (2). The connection relationship is as follows: energy transmission antenna AT1～ATNDirect and band pass filter BPF1～BPFNConnected with each other, the back end passes through a switch R1～RNSeparately connected waveform detection module WDM1～WDMNSUM combiner SUM1～SUMN. At the transmitting device TR1In, combiner SUM1Each of the two circuits is respectively connected with an adjustable power amplifier PA1_F1～PA1_FAConnected at their rear ends with phase shifters PS, respectively1_F1～PS1_FAAre connected with the power divider PD _ F respectively1～PD_FAIs connected to the first port of the other transmitting devices TR2～TRNSUM of combiner2～SUMNBack end connection mode and combiner SUM1The same is true. Power divider PD _ F1～PD_FARespectively corresponding to the microwave power source OSC _ F1～OSC_FAAre connected.
The invention increases the number of the energy transmission frequency points of the system by increasing part of the topological structure of the transmitting device group; the arrangement of the transmitting device groups can be determined according to the boundary shape of a specific energy transmission scene, can be square, circular, irregular graphs and the like, and can also be arranged by adopting a non-equidistant sparse array; the antennas adopted in the transceiver group can be selected according to the actual application requirements, and can be omnidirectional dipole antennas or microstrip patch antennas, and the resonance point and the bandwidth of the antennas are determined according to the application requirements of an actual system; in order to avoid the multi-frequency signal being fed into the adjustable power amplifier at the same time to generate the intermodulation signal component, the embodiment controls only the single-frequency energy transmission signal through the adjustable power amplifier and the phase shifter, and then the combiner is used for superposition to generate the multi-frequency signal, thereby avoiding the energy loss caused by the intermodulation component.
Based on the above device, the multi-frequency multi-target selective energy transmission method and system of the embodiment specifically comprise:
step 1, selecting energy transmission frequency points of a multi-frequency energy transmission system
Step 1-1. construction of energy transmission system
The system model adopted in this example is, as shown in fig. 4, in a metal reverberation chamber of 60cm × 60cm × 15cm, for a target energy transmission area of 12cm × 12cm in the middle, 9 receiving devices are respectively placed at positions where energy transmission is required, and numbered EC from left to right and from top to bottom1～EC9The set of receiving devices ECG constituting the energy delivery system is shown in fig. 5.
Meanwhile, 16 transmitting devices are arranged at the periphery of the metal reverberation cavity at 12cm intervals at equal intervals and are arranged from the top left vertexHour hand number TR1～TR16A group TRM of transmitting means constituting the energy transmission system is shown in fig. 6. The 9 receiving devices and the 16 transmitting devices adopt patch monopole antennas with the center frequency of 2.45GHz and the bandwidth of 500 MHz.
Step 1-2, extracting channel parameters of the energy transmission system
Based on the energy transmission system constructed above, the maximum multipath time delay tau in the energy transmission system is detectedmax40ns, corresponding to a coherence bandwidth of
Figure RE-GDA0002361348840000081
Discretizing the energy transmission bandwidth range of the system from 2.2GHz to 2.7GHz at the frequency interval of 50MHz to obtain 10 frequency points f1,…,f10。
Extracting system energy transmission channel parameters under the 10 different frequency points, wherein the specific operation steps are as follows:
(1) at the receiving device group, OSC1～OSC9All select frequency points as f1Of the sinusoidal signal source of, make the switch S1And OSC1To each other, the rest S2～S9Then respectively communicate with PRU2～PRU9Connected to a signal source OSC1The generated detection signal is fed into a receiving device EC1Performing the following steps;
(2) at the transmitting set of devices, switch R1～R16Respectively with WDM1～WDM16Connected from WDM1～WDM16Respectively extracting frequency points f from the recorded waveforms1The amplitude and phase of (2) constitute the receiving means EC1And a transmitting set TR1～TR16At frequency point f1Lower sinusoidal signal channel parameter matrix h11∈C16×1；
(3) With successive replacement of the receiving means EC2…,EC9Repeating the steps (1) and (2) to enable the device, and respectively measuring the TR with the surrounding transmitting device group1～TR16The channel parameter matrix in between is h21,…,h91That is, at frequency point f1Channel parameter of lower sinusoidal signalThe number matrix is: h1＝[h11,...,h91]T∈C9×16；
(4) By varying the OSC of the feed of the receiving means separately1～OSC9Has a frequency point of f2,…,f10Repeating the steps (1), (2) and (3) to obtain the frequency point f2,…,f10The following energy transmission system sinusoidal signal channel parameter matrix is: h2，…，H10。
Step 1-3. selection of frequency point of energy transmission system
Selecting all receiving devices EC in the energy transmission area1～EC9As the targets to be energy-transferred, the total efficiency of energy transfer for these 9 targets to be energy-transferred represents the total efficiency of the entire energy transfer area.
Utilizing the energy transmission channel parameter H extracted in the step 1-21,…,H10Calculating matrix under 10 different frequencies by using MATLAB software
Figure RE-GDA0002361348840000091
The calculation results are shown in table 1. Selecting the frequency points corresponding to the two maximum values in the table according to the size sequence, i.e. selecting the frequency points corresponding to the two maximum values in the table
Figure RE-GDA0002361348840000092
And taking the two frequency points as energy transmission frequency points of the system.
TABLE 1.10 maximum eigenvalues of the matrix at different frequency points
Figure RE-GDA0002361348840000093
Step 2, realizing multi-target selective wireless energy transmission
Step 2-1, setting system optimization variables and optimization indexes
Selecting a receiving device needing energy transmission, and respectively selecting 3 to-be-transmitted energy targets EC from 9 receiving devices4、EC5、EC6And the other 6 non-energy-transmission targets are EC1、EC2、EC3、EC7、EC8、 EC9。
The system optimization variables are set as follows:
setting two frequencies
Figure RE-GDA0002361348840000094
And
Figure RE-GDA0002361348840000095
weighting factor x of the underfed signal1＝[0,0,0,x41,x51,x61,0,0,0]T、x2＝[0,0,0,x42,x52,x62,0,0,0]T。
The system optimization indexes are set as follows:
the indexes considered by the multi-frequency energy transmission system are a side lobe value SLL and an efficiency value eta, and in order to consider the two energy transmission indexes of the system, a system maximum efficiency threshold eta is setth0.8 and minimum side lobe threshold SLLthSetting the optimized weight coefficient of the two as w to be-10 dB1＝1、w2The two joint optimization indexes are expressed by a COST function COST as 10: COST ═ w1·(SLL-SLLth)+w2·(ηth-η)。
Step 2-2. optimization of system feed-in signal
According to the selected 3 targets EC to be energy-transmitted4、EC5、EC6The power distribution ratio w' between the 3 targets to be supplied is set to [1,1]I.e. satisfy Pr,4＝Pr,5＝Pr,6. In order to obtain the optimal feed signal of the system under 2 energy transmission frequency points, a weighting factor x is used1、x2In order to optimize variables, the two indexes of the side lobe value SLL and the energy transmission efficiency eta of the system are jointly optimized, and the specific optimization problem can be represented as follows:
Figure RE-GDA0002361348840000101
s.t.Pr,4＝Pr,5＝Pr,6
to this questionSolving the problem, wherein the simplex algorithm is adopted to obtain the optimal weighting factor which minimizes the COST as x1 opt、x2 optFrequency of available
Figure RE-GDA0002361348840000102
And
Figure RE-GDA0002361348840000103
the lower feed-in signals are respectively
Figure RE-GDA0002361348840000104
Step 2-3. transmission of system feed-in signal
The feed-in signals s of all frequency points are obtained through the calculation or optimization1、s2Adding the signals s to s1+s2The total feed-in signal is fed into N transmitting devices TR respectively1～TRNIn the middle, 3 expected targets EC to be energy-output can be realized4、EC5、EC6And the energy transmission with high efficiency and low side lobe is carried out.
The specific operation steps are divided into the following three steps:
(1) at the receiver group, switch S1～S9And PRU1～PRU9Connecting; at the transmitting set of devices, switch R1～R16And combiner SUM1～SUM16Connected to, OSC _ F1Selecting a microwave power source, OSC _ F, capable of generating sinusoidal signals with a frequency of 2.45GHz2Selecting a microwave power source capable of generating a sinusoidal signal with the frequency of 2.55 GHz;
(2) according to 2.45GHz1Adjusting the amplitude and phase of each path in the PA filter to adjust the PA1_F1～PA16F1 and PS1_F1～PS16_F1Each path generates 2.45GHz sinusoidal signals with corresponding amplitude and phase; similarly, according to 2.55GHz feed signal s2Adjusting the amplitude and phase of each path in the PA filter to adjust the PA1_F2～PA16_F2And PS1_F2～PS16_F2Each path generates 2.55GHz sinusoidal signals with corresponding amplitude and phase; each path of the generated single-tone sinusoidal signals with two frequencies passes through a combiner SUM1～SUM16Synthesizing a two-tone signal to feed into the antenna in the transmitting device group;
(3) at the receiver group, 3 receivers EC of the expected energy output4、EC5、EC6The antenna receives the dual-frequency energy transmission signals transmitted by the transmitting device group at the same time, and the dual-frequency energy transmission signals pass through the PRU4、PRU5、PRU6Converting the received dual-frequency energy transmission signal into LOAD supply LOAD4,LOAD5,LOAD6The direct current energy used. At the same time, the other 6 receiving devices EC with unexpected energy transmission1、EC2、EC3、EC7、EC8、 EC9And lower side lobe energy is generated.
If the energy transmission scene is changed, skipping to the step 1, selecting the frequency of the multi-frequency wireless energy transmission system again, and then sequentially executing the operation in the step 2; if the energy transmission scene is not changed and only the target to be transmitted is changed, the user only needs to jump to the step 2 and sequentially executes the related operations in the step 2 again, and then selective wireless energy transmission of the newly selected target can be achieved.
In the embodiment, the electromagnetic simulation software CST Studio Suite 2016 is used for simulating the receiving device EC4,EC5,EC6The field distribution pattern for energy transfer is shown in fig. 7. It is evident from the figure that the energy is almost exclusively in EC4,EC5,EC6Three targets to be transmitted are gathered, and the energy distribution in the rest positions is small.
In order to verify the universality and the effectiveness of the method, 5 groups of targets to be energy-transmitted are optionally selected in addition in the example for simulation verification, and 6 groups of targets to be energy-transmitted in the simulation of the example are numbered as serial numbers 1-6 in sequence, and respectively: number 1 (EC)4,EC5,EC6) Number 2 (EC)1,EC3,EC5,EC8) Number 3 (EC)1,EC4,EC7,EC8) Serial number of4(EC1,EC2,EC3,EC5,EC8) Number 5 (EC)2,EC4,EC6,EC8) Number 6 (EC)1,EC2,EC3,EC5,EC7,EC8,EC9). These 6 sets of simulation results are compared, as shown in fig. 8, wherein fig. 8(a) is a graph comparing single-frequency and multi-frequency side lobe values, fig. 8(b) is a graph comparing single-frequency and multi-frequency efficiency values, and fig. 8(c) is a graph comparing single-frequency and multi-frequency COST values. It can be seen from the figure that, under the condition of multi-target energy transmission of any combination, the side lobe value and the efficiency value of the multi-frequency energy transmission signal are optimal compared with a single frequency, and the joint optimization index COST of the side lobe value and the efficiency value is always at the minimum value, which indicates that the wireless energy transmission mode of the multi-frequency energy transmission signal is an energy transmission method which can give consideration to both high efficiency and low side lobe.

Claims (2)

1.一种多频多目标选择性无线输能方法，包括以下步骤：1. A multi-frequency multi-target selective wireless energy transmission method, comprising the following steps: 步骤1.选取多频输能系统的输能频点Step 1. Select the energy transmission frequency point of the multi-frequency energy transmission system 步骤1-1.构建输能系统Step 1-1. Build an energy transmission system 在目标输能区域放置M个接收装置EC1～ECM，构成输能系统的接收装置组ECG；M receiving devices EC 1 -EC M are placed in the target energy transmission area to form a receiving device group ECG of the energy transmission system; 在输能区域外侧环绕放置N个发射装置TR1～TRN，构成输能系统的发射装置组TRM；N number of transmitting devices TR 1 to TR N are placed around the outside of the energy transmission area to form a transmitting device group TRM of the energy transmission system; 步骤1-2.提取输能系统信道参数Step 1-2. Extract the channel parameters of the energy transmission system 基于步骤1-1构建的输能系统，检测输能系统中的最大多径时延τmax，从而得到对应的相干带宽为
Figure FDA0003139129460000011
以2ΔB的频率间隔，将系统采用的输能带宽范围[fL，fH]离散化得到K个频点f1，…fk，…fK，1≤k≤K，并提取出这K个不同频点下的输能系统信道参数矩阵H1，…Hk，…HK，包括步骤如下：Based on the energy transmission system constructed in step 1-1, the maximum multipath delay τ max in the energy transmission system is detected, and the corresponding coherence bandwidth is obtained as
Figure FDA0003139129460000011
With a frequency interval of 2ΔB, discretize the energy transmission bandwidth range [f L , f H ] used by the system to obtain K frequency points f 1 , ... f k , ... f K , 1≤k≤K, and extract the K The channel parameter matrix H 1 , ... H k , ... H K of the energy transmission system at different frequency points includes the following steps: (1)将频率为f1的正弦信号通过接收装置EC1～ECM发射，N个发射装置TR1～TRN接收并记录该正弦信号，即总共M组频率为f1的信道参数矩阵表示为H1＝[h11，...hm1，...hM1]T∈CM×N，其中，hm1表示第m个接收装置ECm与N个发射装置TR1～TRN之间频率为f1的幅度相位信息，1≤m≤M，上标T表示矩阵转置，CM×N表示M×N的复矩阵；(1) The sinusoidal signal with the frequency f 1 is transmitted through the receiving devices EC 1 ˜EC M , and the N transmitting devices TR 1 ˜TR N receive and record the sinusoidal signal, that is, a total of M groups of channel parameters with the frequency f 1 are represented by the matrix is H 1 =[h 11 ,...h m1 ,...h M1 ] T ∈C M×N , where h m1 represents the difference between the mth receiving device EC m and the N transmitting devices TR 1 to TR N The amplitude and phase information whose inter-frequency is f 1 , 1≤m≤M, the superscript T represents matrix transpose, and C M×N represents the complex matrix of M×N; (2)另外选用频率为f2，…fk，…fK的正弦信号，依次重复进行上述操作，提取频率f2，…fk，…fK下的输能系统信道参数矩阵H2，…Hk，…HK；(2) In addition, select sinusoidal signals with frequencies f 2 , ... f k , ... f K , repeat the above operations in turn, and extract the energy transmission system channel parameter matrix H 2 at frequencies f 2 , ... f k , ... f K , ...H k , ... H K ; 步骤1-3.输能系统频点的选择Step 1-3. Selection of frequency points of energy transmission system 选取输能区域所有接收装置EC1～ECM作为待输能目标，这M个待输能目标输能的总效率代表整个输能区域的总效率；Select all the receiving devices EC 1 to EC M in the energy transmission area as the energy transmission targets, and the total energy transmission efficiency of the M energy transmission targets to be transmitted represents the total energy transmission efficiency of the entire energy transmission area; 在K个不同频点下，对所有接收装置的输能效率计算通过公式
Figure FDA0003139129460000012
求解，其中ηk表示在第k个频点下的输能效率，λmax(·)表示矩阵的最大特征值，
Figure FDA0003139129460000014
表示输能系统信道参数矩阵Hk的共轭转置；Under K different frequency points, the energy transmission efficiency of all receiving devices is calculated by the formula
Figure FDA0003139129460000012
Solve, where η k represents the energy transmission efficiency at the kth frequency point, λ max ( ) represents the maximum eigenvalue of the matrix,
Figure FDA0003139129460000014
represents the conjugate transpose of the channel parameter matrix H k of the energy transmission system; 输能频点的选取操作步骤如下：The selection operation steps of the energy transmission frequency point are as follows: (1)利用步骤1-2提取的输能系统信道参数矩阵H1，…，HK，结合公式
Figure FDA0003139129460000013
计算出K个不同频点下矩阵
Figure FDA0003139129460000021
的最大特征值
Figure FDA0003139129460000022
(1) Using the energy transmission system channel parameter matrix H 1 , . . . , H K extracted in step 1-2, combined with the formula
Figure FDA0003139129460000013
Calculate the matrix under K different frequency points
Figure FDA0003139129460000021
The largest eigenvalue of
Figure FDA0003139129460000022
 (2)将K个最大特征值按照大小顺序依次排列，选取其中的A个最大值
Figure FDA0003139129460000023
1≤ka≤kA≤K，其对应频点分别为
Figure FDA0003139129460000024
那么该A个频点即为输能系统所选取的输能频点；(2) Arrange the K largest eigenvalues in order of size, and select the A largest among them
Figure FDA0003139129460000023
1≤ka ≤k A ≤K, the corresponding frequency points are
Figure FDA0003139129460000024
Then the A frequency points are the energy transmission frequency points selected by the energy transmission system; 步骤2.多目标选择性无线输能的实现Step 2. Implementation of multi-target selective wireless energy transmission 步骤2-1.设定系统优化变量及优化指标Step 2-1. Set system optimization variables and optimization indicators 根据实际应用需求，选出需要输能的E个接收装置
Figure FDA0003139129460000025
作为待输能目标，其余M-E个接收装置
Figure FDA0003139129460000026
即为非待输能目标；According to the actual application requirements, select E receiving devices that need to transmit energy
Figure FDA0003139129460000025
As the target to be transmitted, the remaining ME receiving devices
Figure FDA0003139129460000026
That is, the non-to-be-transmitted energy target; 设定系统优化变量如下：The system optimization variables are set as follows: 设置选取的A个不同输能频点下的加权因子分别为
Figure FDA0003139129460000027
其中
Figure FDA0003139129460000028
Figure FDA0003139129460000029
表示在频率
Figure FDA00031391294600000210
下第m个接收装置的加权因子，若ECm属于E个待输能目标，则
Figure FDA00031391294600000211
为包含幅相信息的复数变量，若ECm属于M-E个非待输能目标，则
Figure FDA00031391294600000212
The weighting factors under the selected A different power transmission frequency points are set as
Figure FDA0003139129460000027
in
Figure FDA0003139129460000028
Figure FDA0003139129460000029
expressed in frequency
Figure FDA00031391294600000210
The weighting factor of the next mth receiving device, if EC m belongs to the E energy-transmitting targets, then
Figure FDA00031391294600000211
is a complex variable containing amplitude and phase information. If EC m belongs to ME non-energy-transmitting targets, then
Figure FDA00031391294600000212
 设置系统优化指标如下：Set the system optimization indicators as follows: (1)M-E个非待输能目标处
Figure FDA00031391294600000213
接收到的最大功率值与E个待输能目标
Figure FDA00031391294600000214
处接收的最小功率值之比，定义为输能系统的旁瓣值SLL；(1) ME non-to-be-transmitted energy targets
Figure FDA00031391294600000213
Received maximum power value and E targets to be delivered
Figure FDA00031391294600000214
The ratio of the minimum power value received at the power transmission system is defined as the side lobe value SLL of the energy transmission system; (2)E个待输能目标
Figure FDA00031391294600000215
接收的总功率与N个发射装置TR1～TRN发射的总功率之比，定义为输能系统的效率值η；(2) E targets to be lost
Figure FDA00031391294600000215
The ratio of the total power received to the total power transmitted by the N transmitting devices TR 1 to TR N is defined as the efficiency value η of the energy transmission system; (3)为了兼顾系统的两个输能指标，设置最大效率阈值ηth与最小旁瓣阈值SLLth，用代价函数COST表示两者联合优化指标：COST＝w1·(SLL-SLLth)+w2·(ηth-η)，w1、w2表示SLL与η之间的优化权重系数；(3) In order to take into account the two energy transmission indicators of the system, the maximum efficiency threshold η th and the minimum sidelobe threshold SLL th are set, and the cost function COST is used to represent the joint optimization index of the two: COST=w 1 ·(SLL-SLL th )+ w 2 ·(η th −η), w 1 and w 2 represent the optimization weight coefficient between SLL and η; 步骤2-2.系统馈入信号的优化Step 2-2. Optimization of the system feed signal 根据实际需求，设定出E个待输能目标之间的功率分配比w′＝[w′1，w′2，…，w′E]，即满足
Figure FDA00031391294600000216
其中
Figure FDA00031391294600000217
表示E个待输能目标
Figure FDA00031391294600000218
分别接收到的输能信号功率；为了得到系统A个输能频点下的最佳馈入信号，以加权因子为优化变量，对系统的旁瓣值SLL、输能效率η两指标进行联合优化，具体优化问题表征如下：According to the actual demand, the power distribution ratio w'=[w' 1 , w' 2 , ..., w' E ] among the E energy-transmission targets is set, that is, it satisfies the
Figure FDA00031391294600000216
in
Figure FDA00031391294600000217
Represents E energy targets to be lost
Figure FDA00031391294600000218
The power of the received energy transmission signal respectively; in order to obtain the best input signal at the A transmission frequency point of the system, the weighting factor is used as the optimization variable, and the two indicators of the side lobe value SLL and the energy transmission efficiency η of the system are jointly optimized. , the specific optimization problem is characterized as follows:
Figure FDA0003139129460000031
Figure FDA0003139129460000031
Figure FDA0003139129460000032
Figure FDA0003139129460000032
 采用全局优化算法求出使得COST最小的一系列最优加权因子
Figure FDA0003139129460000033
即可求得A个输能频点下的馈入信号为
Figure FDA0003139129460000034
其中
Figure FDA0003139129460000035
Using the global optimization algorithm to find a series of optimal weighting factors that minimize COST
Figure FDA0003139129460000033
It can be obtained that the input signal at A frequency points of energy transmission is
Figure FDA0003139129460000034
in
Figure FDA0003139129460000035
 步骤2-3.系统馈入信号的传输Step 2-3. Transmission of the system feed signal 通过上述优化得到各个频点的馈入信号
Figure FDA0003139129460000036
叠加成总馈入信号
Figure FDA0003139129460000037
将该总馈入信号分别馈入对应的N个发射装置TR1～TRN中，即可实现对预期E个待输能目标进行高效、低旁瓣的能量传输。Through the above optimization, the input signal of each frequency point is obtained
Figure FDA0003139129460000036
Superimposed into total feed signal
Figure FDA0003139129460000037
The total input signal is respectively fed into the corresponding N transmitting devices TR 1 to TR N , so that the energy transmission with high efficiency and low side lobe to the expected E energy-transmitting targets can be realized. 2.如权利要求1所述的一种多频多目标选择性输能方法，其特征在于，步骤2-2中，所述全局优化算法为单纯形算法、遗传算法、或者蚁群算法。2 . The multi-frequency and multi-object selective energy transmission method according to claim 1 , wherein, in step 2-2, the global optimization algorithm is a simplex algorithm, a genetic algorithm, or an ant colony algorithm. 3 .
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