CN113346634B

CN113346634B - Method and system for increasing total energy transmission amount in magnetic resonance charging system

Info

Publication number: CN113346634B
Application number: CN202110698613.7A
Authority: CN
Inventors: 周颢; 周王球; 李向阳
Original assignee: University of Science and Technology of China USTC
Current assignee: University of Science and Technology of China USTC
Priority date: 2021-06-23
Filing date: 2021-06-23
Publication date: 2022-07-15
Anticipated expiration: 2041-06-23
Also published as: CN113346634A

Abstract

The invention discloses a method and a system for improving the total energy transmission amount in a magnetic resonance charging system, wherein the method comprises the following steps: adjusting the TX-RX mutual inductance by using a specially-made TX coil with adjustable size; and separating the strongly coupled RX pairs by a grouping mechanism and using time division multiplexing to avoid charging them simultaneously. The technical scheme provided by the embodiment of the invention considers two charging paradoxs in the PDL maximization problem of the MRC-WPT system for the first time. Corresponding solutions are respectively adopted for the two charging paradox phenomena, so that the two common charging paradox problems in the actual system are well solved, the charging efficiency of the actual system is greatly improved, and the maximization of PDL is realized.

Description

Method and system for increasing total energy transmission amount in magnetic resonance charging system

Technical Field

The invention relates to the technical field of electronics, in particular to a method and a system for improving energy transmission total amount in a magnetic resonance charging system.

Background

With the rapid development of intelligent technologies, more and more intelligent terminal devices bring convenience to daily life of people, such as mobile phones, tablet computers, wearable devices and the like. Along with the development of intelligent technology, the charging management technology for intelligent equipment is also continuously improved, and the Wireless Power Transfer (WPT) technology is brought forward, so that convenience is provided for charging management of people.

Generally, there are two main implementations of a Magnetic field medium-based wireless charging system, including an electromagnetic Coupling (IC) based approach and a Magnetic Resonance Coupling (MRC) based approach. The charging system based on the MRC further improves the charging distance and efficiency by utilizing magnetic field resonance compared with an IC-based mode.

In recent years, beam convergence (Beamforming) technology is introduced into a magnetic resonance charging system for supporting Multiple-Input Multiple-Output (MIMO) application scenarios. Based on this, the issue of ensuring optimal scheduling of the current or voltage of the Transmitter (TX) with energy gathered by the Receiver (RX) becomes a corresponding research hotspot. At present, most of the existing work related to MRC-WPT (magnetically coupled resonant Wireless Power Transfer) is focused on maximizing the system energy Transfer Efficiency (PTE) and its variants.

At present, the upper bound of PTE maximization has been discussed and leads to conclusions that all have in common that strong TX-RX coupling would yield high PTE (implicit requirement: voltage at TX end of charging system is not limited). However, in a practical voltage-limited system, the real received Power (PDL) of RXs needs to be of more concern than the PTE of the system. Moreover, the scheme of PTE maximization of the existing system cannot guarantee the maximization of PDL.

Disclosure of Invention

The invention aims to provide a method and a system for improving the total energy transmission amount in a magnetic resonance charging system, so as to solve the problem that the maximization of PDL cannot be realized in the prior art.

The purpose of the invention is realized by the following technical scheme:

a method of increasing the amount of energy transferred in a magnetic resonance charging system, comprising:

in a magnetic resonance charging system, acquiring mutual inductance coupling values of a transmitting end and a receiving end;

when the mutual inductance coupling value is determined to be not in accordance with the preset value, the mutual inductance coupling value between the sending end and the receiving end is adjusted in a mode of adjusting the size of a coil of the sending end or adjusting the distance between the sending end and the receiving end, and the mutual inductance coupling value is enabled to be in accordance with the preset value;

and carrying out energy transmission based on the adjusted mutual inductance coupling value between the sending end and the receiving end.

The step of adjusting the mutual inductance coupling value between the sending end and the receiving end comprises the following steps:

establishing a coil array at a transmitting end, wherein the coil array corresponds to a plurality of selectable array states, and different array states correspond to different effective coil scales in the coil array;

and adjusting the mutual inductance coupling value between the transmitting end and the receiving end by adjusting the array state of the coil array.

When the magnetic resonance charging system comprises a plurality of receiving ends, before the mutual inductance coupling value of the transmitting end and the receiving end is obtained, the method further comprises the following steps:

acquiring mutual inductance coupling values among a plurality of receiving ends, and determining a strong coupling receiving end pair with the mutual inductance coupling value exceeding a preset value according to the mutual inductance coupling values among the plurality of receiving ends:

different charging time slices are respectively distributed to the receiving ends contained by the strong coupling receiving end, and the receiving ends are only allowed to be charged in the time slices distributed to the receiving ends;

and the mutual inductance coupling value of the transmitting end and the receiving end comprises: and acquiring a mutual inductance coupling value between the sending end and the receiving end which is charged at the current time slice.

The process of allowing it to charge only the time slice contents allocated to it comprises:

and sending the charging time slice information which is distributed to the receiving terminal and allows the receiving terminal to charge, wherein the receiving terminal can control the charging starting or stopping state of the receiving terminal according to the received charging time slice information.

The step of determining the strong coupling receiving end pair with the mutual inductance coupling value exceeding the preset value further comprises the following steps:

and separating the determined strong coupling receiving end pairs into the least groups, wherein the groups are used as the basis for allocating different charging time slices, and each group only comprises one receiving end in the strong coupling receiving end pair.

The step of separating the determined strongly coupled receiving end pairs into the least packets comprises:

representing the coupling relation among all receiving ends by adopting an undirected graph, wherein the vertex of the undirected graph corresponds to the receiving ends;

obtaining all maximum cliques of the undirected graph, each maximum clique comprising one or more vertices;

and determining the minimum maximum clique to cover all vertexes of the undirected graph, and determining the grouping of the receiving end according to the minimum maximum clique.

The method further comprises the following steps:

and when a certain packet is determined to be in a time slice allowing charging, executing the operation of acquiring the mutual inductance coupling value of the transmitting end and the receiving end, wherein the receiving end refers to one or more receiving ends contained in the packet allowing charging.

The processing for adjusting the mutual inductance coupling value of the transmitting end and the receiving end comprises the following steps:

and solving through a meta-heuristic algorithm to select an array state which maximizes the received energy of the packet from the array states of the coil arrays, and taking the array state as the working state of the coil array at the transmitting end under the current time slice.

When the sizes of the current charging receiving end and the current transmitting end coil of the charging system are determined, the method further comprises the following steps: aiming at the self-adaptive processing process of the current of the sending terminal, the process is realized based on an ADMM algorithm.

A magnetic resonance charging system comprises a sending end and a receiving end, and further comprises:

the mutual inductance coupling adjusting unit is used for acquiring mutual inductance coupling values of the transmitting end and the receiving end; when the mutual inductance coupling value is determined not to accord with the preset value, the mutual inductance coupling value between the sending end and the receiving end is adjusted in a mode of adjusting the size of a coil of the sending end or adjusting the distance between the sending end and the receiving end, and the mutual inductance coupling value accords with the preset value;

the receiving end time slice distribution unit is used for determining a strong coupling receiving end pair with the mutual inductance coupling value exceeding a preset value according to the mutual inductance coupling value among a plurality of receiving ends when the magnetic resonance charging system comprises the plurality of receiving ends: different charging time slices are respectively distributed to the receiving ends contained by the strong coupling receiving end, and the receiving ends are only allowed to charge in the time slices distributed to the receiving ends;

when the receiving end time slice allocation unit allocates the charging time slices to one or more receiving ends, the mutual inductance coupling value of the transmitting end and the receiving end, which is obtained by the mutual inductance coupling adjustment unit, refers to the mutual inductance coupling value between the transmitting end and one receiving end which is charged by the current time slice; and energy transmission is carried out between the sending end and the receiving end based on the mutual inductance coupling value between the sending end and the receiving end which is adjusted by the mutual inductance coupling adjusting unit.

According to the technical scheme provided by the invention, the implementation scheme of the method for improving the energy transmission total amount in the magnetic resonance charging system can effectively adjust the inductive coupling value between the transmitting end and the receiving end to enable the inductive coupling value to meet the preset requirement, and further ensure that the maximization of PDL can be realized in the energy transmission process based on the inductive coupling value.

In addition, the embodiment of the invention can also carry out grouping processing on the strong coupling receiving end pairs in the plurality of receiving ends, so that each receiving end of the strong coupling receiving end pairs respectively starts the charging process in different time periods, thereby effectively avoiding the problem of PDL reduction caused by strong coupling.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

FIG. 1 is a diagram illustrating the performance evaluation experiment results of a 1TX-1RX system;

FIG. 2 is a schematic diagram of a TX coil provided in accordance with an embodiment of the present invention;

FIG. 3 is a diagram illustrating the performance evaluation experiment results of the 1TX-2RXs system;

FIG. 4 is a schematic diagram of an algorithm flow provided by an embodiment of the present invention;

FIG. 5 is a schematic diagram of a top-level solution sample provided in an embodiment of the present invention;

fig. 6 is a schematic diagram of PDL comparison results of the IMP algorithm and other algorithms provided in the embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

In the process of solving the problems in the prior art, practical experimental observation shows that the technical scheme for maximizing the PTE of the existing system cannot well ensure the maximization of the PDL of the system, namely, the practical experimental observation proves that two charging paradox phenomena prove the view:

the first phenomenon is PTE-PDL collision phenomenon: when strong coupling occurs between RXs and TXs in the system, the PTE of the system is high, but the PDL is low;

the second phenomenon is the "isolated" RX pair phenomenon: when the two RX circuits are close to each other, an island is formed by the pair of RX circuits, energy cannot be transmitted into the island, and both PTE and PDL of a system are low.

The two charging paradox phenomena can be essentially attributed to the system impedance mismatch problem from the principle. From the perspective of the TX-side circuit, the equivalent impedance associated with RX is not only associated with the RX-side circuit, but also with TX-RX mutual inductance, and even RX-RX mutual inductance. Therefore, a strong TX-RX/RX-RX mutual inductance means a strong RX-related equivalent impedance, thereby causing a mismatch with the internal impedance of the TX end circuit. The PDL of the system is then low, according to the law of maximum energy transfer.

In order to solve the two charging paradoxs, the technical scheme adopted in the implementation process of the invention mainly comprises the following steps: (1) for the first phenomenon, the TX-RX mutual inductance can be adjusted by adopting a specially-made TX coil with adjustable size; (2) for the second phenomenon, the strongly coupled RX pairs may be separated by a grouping mechanism and time division multiplexing may be employed to avoid charging them simultaneously. The technical problems to be solved in the process of specifically realizing the corresponding technical scheme mainly comprise: one is the solution problem of the multivariate joint optimization problem itself, which includes: RX grouping decision, TX coil adjustment, and TX end current adaptation; secondly, the cost brought by frequent channel measurement is not favorable for real-time response and rapid optimization of the charging system, and mainly changes of the system charging channel brought by switching RX grouping and adjusting the size of a TX coil.

In order to understand the detailed technical content of the technical solution provided by the present invention described later, the basic circuit theory knowledge of the MRC-WPT system related to MIMO will be introduced first.

Based on an MRC-WPT system comprising N TX coils and Q RX coils, it is assumed that all coils are resonant at the same operating frequency ω. In this system, it is generally believed that there are three different coil couplings (i.e., mutual inductances between the three different coils), respectively: (1) TX coil n₁And n₂Mutual inductance between

(2) Mutual inductance m between TX coil n and RX coil q_n,q(3) RX coil q₁And q is₂Mutual inductance between them

Based on kirchhoff circuit formula, the following circuit derivation formula can be obtained in the MRC-WPT system:

where superscript-t-type and-1 represent the transpose operation and inversion operation, respectively, of the matrix.

And

representing the TX and RX side current vectors respectively,

respectively, represent the TX terminal voltage vector and,

and

representing the resistances of TX n and RX q, respectively.

The two aforementioned charging paradox phenomena causes are analyzed and solutions are provided for the two charging paradox phenomena, so as to maximize the total amount of energy transmission in the charging system.

PTE-PDL conflict phenomenon and solution

It is known from the conclusion about MRC-WPT system PTE maximization that strong TX-RX coupling will result in high system PTE. However, this conclusion has an implicit precondition that the TX terminal voltage is not limited. However, in contrast, in practical systems, the TX terminal voltage is often limited. Although a strong TX-RX coupling would still produce a high system PTE at this time, the system PDL would be very low due to the limited TX terminal voltage.

This phenomenon is referred to as "PTE-PDL collision phenomenon" above. The specific cause of this phenomenon can be explained in detail by a simple example. In particular based on a practical scenario of 1TX-1 RX. From the above equation (2), the voltage on the coil for TX1 can be obtained

And current of

The relationship between:

when the coil RX1 is close to the TX1, the equivalent impedance of the coil RX1 at the TX end circuit becomes large, i.e., the equivalent impedance becomes large

Because of

Is limited in practical systems, so it results in

It becomes very small resulting in a low total system power and PDL. As shown in fig. 1(a), the experimental results show that strong TX-RX coupling can produce high PTE but low PDL, for example, when TX1 is 5cm away from RX1 vertically, system PTE reaches 99.98% but PDL is only 0.01W.

In order to effectively solve the above-described problem of generating low PDL, a method including impedance matching may be employed. However, to simplify the design of the TX end, the system operating frequency ω and the TX coil internal impedance are assumed

Is stationary. Besides, considering some low-capability Internet of Things (IoT) devices, it is also assumed that the RX-side impedance

Is not adjustable. Therefore, as can be seen from equation (6), the best way to perform impedance matching is to adjust the TX-RX coupling m_1,1(i.e., TX-RX mutual inductance). Two methods that can be used to adjust the TX-RX coupling are known from experimental results: one is to change the TX-RX distance and the other is to adjust the TX coil size. There is a need to consider the implementation of adjusting the TX-RX distanceThe present invention mainly adopts the method of adjusting the size of the TX coil to adjust the TX-RX coupling.

For the above "PTE-PDL collision phenomenon", its corresponding solution will be described below:

the corresponding solution may include: in a magnetic resonance charging system, acquiring mutual inductance coupling values of a transmitting end and a receiving end; and judging whether the mutual inductance coupling value accords with a preset value, and if not, adjusting the mutual inductance coupling value between the sending end and the receiving end in a mode of adjusting the coil size of the sending end or the distance between the receiving end and the sending end to enable the mutual inductance coupling value to accord with the preset value, so that the maximization of PDL can be realized between the sending end and the receiving end in the process of carrying out energy transmission based on the adjusted mutual inductance coupling value.

In a specific implementation process, a coil array can be established at a sending end, the coil array corresponds to a plurality of selectable array states, and different array states correspond to different effective coil sizes in the coil array; thus, the mutual inductance coupling value between the transmitting end and the receiving end can be adjusted by adjusting the array state of the coil array.

Further, as shown in fig. 2, a TX coil whose size is adjustable may be employed, and each size of the coil is assumed as one state of the coil. That is, it is assumed that each TX coil (TX circuit) has S states (states 0, … …, states-2, states-1), for example, a state0 indicates that the TX coil is not fully connected to the circuit, and conversely, a state S-1 indicates that the TX coil is fully connected to the circuit; the state switch (state switch with resonant capacitor) in the dashed box of fig. 1 is a control switch capable of adjusting and selecting the TX coil to be in one of S states. To demonstrate the feasibility of this approach, an experiment was performed under the above-described scenario of 1TX-1RX (where the TX coil has S-10 states). As shown in fig. 1(b), the optimal TX-RX coupling can be found by adjusting the TX coil size, thereby achieving the optimal system PDL.

(II) "isolation" RX Pair phenomenon and its solution

In daily life, people often stack some smart devices together, for example, a mobile phone on a tablet computer. However, in practical charging systems, two RXs that are too close together can form an "island," and the energy transmitted from the transmitter cannot be transferred to RXs. That is, two strongly coupled RXs will result in low PDL, while two weakly coupled RXs will both receive the desired power.

The above phenomenon is called the "isolated' RX pair phenomenon". Here, the cause of this phenomenon is also explained in detail by a simple example. Assuming a scenario of 1TX-2RXs, the TX-side current can be obtained according to equation (1)

And RX terminal current

(

Equivalent) of the following:

when coils RX1 and RX2 are in close proximity, the RX-RX coupling between them becomes large, i.e. the coils are close to each other

It becomes large. When in

Much larger than the coupling m between TX-RX_1,1And m_1,2Equation (7) shows that even at this time, the TX terminal current

Very large, RX-side current

Will still be very goodIs small. Thus, in this case, both the system PTE and PDL would be small. Through verification experiments, when the vertical distance between RX1 and TX1 is fixed to be 35cm, RX2 is moved by taking RX1 as a reference. As shown in fig. 3, when the two RXs are very close together, both the system PTE and PDL will be low.

For the above-mentioned "isolated' RX pair phenomenon", the following solution may be specifically provided:

to cope with this ' isolated ' RX pair phenomenon ', technical means that may be employed include impedance matching. For some low-capability IoT (internet of things) devices, however, their internal impedance (i.e.,

and

) Is not adjustable. Thus, in order to avoid impedance mismatches caused by strong RX-RX couplings, the strongly coupled RX may be assigned different charging time slices, respectively, for the involved RX and only allowed to charge within the time slice assigned to it.

Specifically, when a plurality of RX are included in the magnetic resonance charging system, obtaining mutual inductance coupling values among the plurality of RX, and determining a strong coupling RX pair with the mutual inductance coupling value exceeding a preset value according to the mutual inductance coupling values among the plurality of RX; then, different charging time slices are respectively allocated to the RX included in the strong coupling RX pair. After the time slice allocation is completed, charging time slice information which is allocated to the time slice and allows the time slice to be charged can be sent to the RX, and the RX controls the charging starting or stopping state of the RX according to the received charging time slice information so as to ensure that the RX included in the strong coupling RX is charged in different time periods respectively and avoid the RX cannot be effectively charged due to mutual interference.

Further, the problem caused by the phenomenon of 'isolated' RX pairs can be solved by grouping strongly coupled RX pairs, that is, after determining the strongly coupled receiving end pairs whose mutual inductance coupling value exceeds a predetermined value, separating the determined strongly coupled receiving end pairs into the least groups, wherein the groups are used as the basis for allocating different charging time slices, and each group only contains one receiving end of the strongly coupled receiving end pairs. For example, assuming there are 3 RXs, where RX1 and RX2 are strongly coupled, then the possible 3 groups include: {(1),(2,3)},{(1,3),(2)},{(1,3),(2,3)}. After the RX packets are performed, time scheduling may be specifically performed between different RX packets in a time division multiplexing manner, that is, an independent time slice is allocated to each RX packet, so that the strongly coupled RX1 and RX2 are not charged simultaneously, and thus the problem of PDL reduction caused by interference between the two during the charging process is effectively avoided.

It should be noted that, after the packet operation is completed and the time slice allocation is completed, when a certain packet is determined to be in a time slice allowing charging, the operation of acquiring mutual inductance coupling values of TX and RX in the solution to the "PTE-PDL collision phenomenon" may be performed, where RX refers to one or more RX included in the packet allowing charging. That is, in this case, for the solution to the above-mentioned "PTE-PDL collision phenomenon", it is specifically necessary to acquire the mutual inductance coupling value between the TX and the RX charged at the current time slice, rather than acquiring the mutual inductance coupling value between the TX and the other RX not charged.

In a specific implementation process of the embodiment of the present invention, for a system with a limited actual voltage, in order to well solve the two charging paradox phenomena, an RX grouping time-sharing charging technology and a TX coil state adjusting mode may be simultaneously utilized in the system to implement a maximized system PDL.

In order to realize the maximized system PDL, the system architecture applied in the embodiment of the present invention basically requires the following:

assuming that the MRC-WPT system comprises one system comprising N TX coils and Q RX coils, then:

at the TX end, a multi-state tunable TX coil as shown in fig. 2 may be used, while assuming that both the phase and amplitude of the TX end voltage are tunable. In addition to this, it is assumed that all TX coils constitute a TX array.

At the RX side, all RXs switches are needed that can receive commands from the TX side and can control its own charging or not. At the same time, it is also assumed that all RXs are capable of feeding back their impedance information either out-of-band (e.g., bluetooth) or in-band.

Based on the system architecture, the embodiment of the invention comprises the following optimization variables in the implementation process:

RX grouping policy candidates: the set of all possible RX grouping policy candidates is denoted with the symbol Ψ, and any one RX grouping policy candidate in the set is denoted with the symbol G ∈ Ψ. Obviously, there are | G | RX packets in the packet policy candidate G. Since time scheduling is performed after the RX packets are made, it is assumed that a time slice t is allocated to each RX packet G ∈ G_gAnd simultaneously, the requirement that the total charging time does not exceed the set time T is met.

TX array state: using vector states

Indicating the state of one TX array, e.g.,

indicating that each TX coil in the TX array is in state 0. In addition, the symbol Φ is used to represent the set of possible states of the TX array, i.e.

The TX end current: the scheduling optimization of the TX-side current needs to be done under a certain charging channel (i.e. under the condition that the RX grouping strategy and TX array state are determined), i.e. a given one

When is given one

Then adopt

Representing the TX side current. To avoid ambiguity, it can be directly adopted

Representing the TX side current.

Therefore, in the optimization problem, there are four optimization variables, which are: RX grouping strategy candidate G, time slice Allocation t_gTX array State

TX terminal current

Based on the above four optimization variables, the optimization objectives of the embodiment of the present invention are as follows:

first, the PDL representation for any RX packet g is explicit: as with the scheduling optimization of TX-side current, the optimization for a packet PDL also needs to be discussed under a given channel. Also, the energy transmission relationship between the systems has been explained by the equations (1) to (5).

From the TX current point of view, the energy received by one RX q is expressed as

According to equation (1), the PDL of an RX packet for a given channel can then be expressed as:

where the superscript (#) represents the conjugate transpose operation of the matrix.

To represent

Based on the above formula, in order to achieve fairness in scheduling, the optimization goal of the embodiment of the present invention is to achieve proportional fair scheduling of energy acquisition among RX packets, that is:

to this end, the PDL maximization problem, which achieves proportional fairness, may be formulated as follows:

subject to

wherein constraints (C9a) and (C9b) represent RX packet policy candidate G and TX array State, respectively

Is used as a feasible space. The constraint (C9C) represents the TX terminal voltage limit. The constraint (C9d) represents the charging time limit, i.e., the total charging schedule time and the no-more-than time T.

Based on the above equation (9), it can be seen that the optimization problem (9) is a multivariate joint optimization problem. Therefore, it can be decoupled into the following three sub-problems.

Given charging channel

The following problem of bottom layer voltage adaptation (TXCurrent adaptation, TCA):

s.t.(C9C). (10)

second layer TX Array State Adjustment (TASA) problem under a given RX packet g:

③ consider the PDL proportional fair top-level RX Grouping policy Candidate Decision (RGCD) problem:

s.t.(C9a),(C9d). (12)

after the sub-problems are decoupled, each sub-problem can be efficiently solved in turn. The overall algorithm flowchart provided by the embodiment of the present invention is shown in fig. 4, and specifically includes the following processes:

(1) bottom-level optimization sub-problem (TCA sub-problem) solution

Namely, the bottom layer solution: ADMM-based TX current adaptive Algorithm (Lower-level Solution: ADMM-based Algorithm for TX current application);

before solving the underlying TCA (TX current adaptation) sub-problem, the charging channel is assumed to be { i.e.,

is a known constant. That is, when the currently charged RX (or RX packet) of the charging system and the current sending-end coil size are determined, the corresponding charging channel is a known constant. At this time, it is also necessary to perform self-calibration for the TX currentThe process is adapted.

It can be seen that the TCA sub-problem is a standard semi-positive optimization (SDP) problem that can be solved using existing convex optimization toolkits, such as CVX. However, CVX-based methods require a large number of iterations in the randomization process to ensure a high accuracy approximate solution. In view of the real-time requirement of the charging system, the TCA sub-problem can be converted into a consistent optimization problem, and the consistent optimization problem can be solved efficiently by using an algorithm based on ADMM (alternating direction multiplier method), which is not described in detail herein.

(2) Solving of middle layer optimization subproblem (TASAsub-problemm)

I.e. the middle layer solution: TS-based TX array state adjustment Algorithm (Middle-level Solution: TS-based Algorithm for TX array state adjustment);

the middle layer TASA (TX array state adjustment) sub-problem is to search for the best TX array state to achieve the best packet PDL under a given RX packet. It can be considered as a finite state space (O (S)^|N|) ) search questions.

Based on the TX coil as shown in fig. 2, the transitions between TX array states can be considered to be continuous, i.e. the resulting TX-RX coupling is not abrupt. Therefore, the TASA subproblem is well suited to be solved by a meta-heuristic algorithm, such as a Tabu Search (TS) algorithm, so as to select an array state that maximizes the received energy of a packet from the array states of the coil array, and use the array state as the working state of the coil array at the transmitting end in the current time slice. As shown in table 1 below, a TS-based algorithm is presented to solve the TASA sub-problem.

TABLE 1

In table 1, a TS-based TASA solution algorithm implementation process is given, in which a given RX set g is input, and the optimal TX array state selection result can be output through the processes of 1 to 12 in table 1, and the maximization of PDL can be ensured.

(3) Top-level optimization sub-problem (RGCDsub-problemm) solution

Namely, the upper layer solution: a Graph-based RX packet candidate decision Algorithm (Upper-level Solution: Graph-based Algorithm for RX grouping candidate decision);

to solve the top-level RGCD (RX packet candidate decision) sub-problem, strongly coupled RX pairs with mutual inductance coupling exceeding a set threshold may be grouped, each group containing only one of the receiving ends of the strongly coupled RX pairs, and charge time scheduling is performed after grouping. In the process of scheduling the charging time, the grouping is used as the basis for the operation of allocating different charging time slices, i.e. different charging time slices are allocated to different groupings, so as to ensure that the RX in the strongly-coupled RX pair are not charged in the same time slice, and avoid mutual interference.

Regarding charge time allocation, the RGCD sub-problem wants to achieve proportional fairness. Therefore, the best way is to allocate an equal charging time for each RX packet. In addition to this, the number of RX packets should be as small as possible, since a larger number of packets means that the charging time per packet becomes smaller.

In the RX grouping process, in order to achieve the objective of separating all strongly coupled RX pairs into the fewest packets, the RX grouping process may be specifically implemented based on a processing idea of minimum maximum clique vertex coverage of an undirected graph, and as shown in fig. 5, the RX grouping process may specifically include the following steps:

(1) representing the coupling relation among all the RX by using an undirected graph, wherein the vertex of the undirected graph corresponds to the RX, and a connecting line between the vertexes represents that the coupling between the two RX is lower than a preset threshold value, namely that the two RX are not high-coupling RX pairs;

(2) obtaining all maximum cliques of the undirected graph, each maximum clique comprising one or more vertices;

this is a classical NP-hard problem, and due to the limited number of RX in practice, the BronKerbosch algorithm can be used to solve for the largest cliques;

(3) finding the minimum number of maximum cliques to cover all vertexes of the undirected graph, and determining the grouping of the receiving end according to the minimum number of maximum cliques;

the Problem is a Set-Covering (SCP) Problem, and is also a classical NP-complete Problem, and a greedy algorithm can be specifically adopted for solving.

As shown in fig. 5(c), the best RX grouping strategy is obtained: {1,2,3},{3,4,5}. Notably, placing RX3 into each packet may maximize its charging time.

To summarize, referring to fig. 4, the corresponding implementation may include: firstly, executing a process (3) to make an RX grouping candidate decision and giving an RX grouping; then executing a TX array state adjustment algorithm through the procedure (2), and giving one RX packet and one TX array state corresponding to the RX packet; and finally, executing a TX current self-adaption algorithm through the process (1) to determine the corresponding TX end current for the determined group and the determined TX array state.

Through the processing of the process shown in fig. 4, the solution of the sub-problem for each layer is realized, so that the influence of the high coupling between the RX on the charging process can be avoided in a multi-RX charging scenario and during the high coupling between the RX. Additionally, for the RX being charged, the TX end may also select the best matched TX coil state for it to avoid affecting the charging process due to strong mutual inductance between TX and RX.

Based on the processing procedure shown in fig. 4, an embodiment of the present invention further provides a magnetic resonance charging system, which includes a sending end and a receiving end, and further includes:

a mutual inductance coupling adjustment unit, specifically configured to implement the process (2) in fig. 4, and specifically configured to obtain a mutual inductance coupling value of the transmitting end and the receiving end; when the mutual inductance coupling value is determined to be not in accordance with the preset value, the mutual inductance coupling value between the sending end and the receiving end is adjusted in a mode of adjusting the coil size of the sending end or adjusting the distance between the sending end and the receiving end, and the mutual inductance coupling value is made to be in accordance with the preset value;

a receiving end time slice allocation unit, which is specifically configured to implement the process (3) in fig. 4, and is configured to determine, when a plurality of receiving ends are included in the magnetic resonance charging system, a strong coupling receiving end pair whose mutual inductance coupling value exceeds a predetermined value, according to a mutual inductance coupling value between the plurality of receiving ends: different charging time slices are respectively distributed to the receiving ends contained by the strong coupling receiving end, and the receiving ends only allow the receiving ends to charge in the time slices distributed to the receiving ends;

when the receiving end time slice allocation unit allocates charging time slices to one or more receiving ends, the mutual inductance coupling value of the sending end and the receiving end acquired by the mutual inductance coupling adjustment unit is the mutual inductance coupling value between the sending end and one receiving end which is charged by the current time slice; and the mutual inductance coupling value between the sending end and the receiving end after the mutual inductance coupling adjustment unit adjusts is used for energy transmission.

After the mutual inductance coupling adjustment unit and the receiving end time slice allocation unit complete their processing functions, corresponding TX end currents may be determined for the transmitting end through the process (1) in fig. 4, and then the entire charging system may charge the RX of the current RX packet based on the corresponding optimized bottom layer, middle layer, and top layer, and the charging process may be implemented to provide the optimal PDL for the RX packet.

In summary, the technical solution provided by the embodiment of the present invention considers two charging paradox phenomena in the PDL maximization problem of the MRC-WPT system for the first time. Corresponding solutions are respectively adopted for the two charging paradox phenomena, so that the two charging paradox problems common in the actual system are well solved, and the charging efficiency of the actual system is greatly improved.

In practical application experiments of the embodiment of the present invention, the algorithm provided by the embodiment of the present invention is deployed on an experimental platform, which includes an MRC-WPT system including a 3 × 2 TX array and RXs.

And performing random placement of the RX for multiple times under different TX-RX distances, and collecting experimental data under different RX placement results. As shown in fig. 6, the algorithm (IMP) provided by the embodiment of the present invention has a better and more stable effect than other comparative algorithms. The specific improvement results of the corresponding IMP algorithm relative to other algorithms are shown in table 2 below:

TABLE 2

It can be seen from the above table 2 that the PDL effect of the charging system is significantly improved by the application of the technical scheme provided by the present invention.

The above description is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are also within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for increasing the amount of energy transferred in a magnetic resonance charging system, comprising:

in a magnetic resonance charging system, acquiring a mutual inductance coupling value of a transmitting end and a receiving end; when the magnetic resonance charging system includes a plurality of receiving terminals, before the obtaining of the mutual inductance coupling value between the transmitting terminal and the receiving terminal, the method further includes: acquiring mutual inductance coupling values among a plurality of receiving terminals, determining a strong coupling receiving terminal pair with the mutual inductance coupling value exceeding a preset value according to the mutual inductance coupling values among the plurality of receiving terminals, respectively allocating different charging time slices for the receiving terminals contained by the strong coupling receiving terminal pair, and only allowing the receiving terminals to be charged in the allocated time slices, wherein the acquiring of the mutual inductance coupling values of the sending terminal and the receiving terminals under the condition comprises the following steps: acquiring a mutual inductance coupling value between a sending end and a receiving end which is charged by the current time slice;

when the mutual inductance coupling value is determined to be not in accordance with the preset value, the mutual inductance coupling value between the sending end and the receiving end is adjusted in a mode of adjusting the size of a coil of the sending end or adjusting the distance between the sending end and the receiving end, and the mutual inductance coupling value is enabled to be in accordance with the preset value; the step of adjusting the mutual inductance coupling value between the transmitting end and the receiving end comprises the following steps: establishing a coil array at a transmitting end, wherein the coil array corresponds to a plurality of selectable array states, and different array states correspond to different effective coil scales in the coil array; adjusting the mutual inductance coupling value between the transmitting end and the receiving end by adjusting the array state of the coil array;

2. The method of claim 1, wherein the process of allowing only the time slice content allocated to the method to be charged comprises:

and sending the charging time slice information which is distributed to the receiving terminal and allows the receiving terminal to charge, wherein the receiving terminal can control the self charging starting or stopping state according to the received charging time slice information.

3. The method of claim 1, wherein determining that the strongly coupled receiving end pair with the mutual inductance coupling value exceeding the predetermined value is back further comprises:

4. The method of claim 3, wherein the step of separating the determined strongly coupled receiving end pair into the fewest packets comprises:

and determining that the minimum number of the maximum cliques cover all vertexes of the undirected graph, and determining the grouping of the receiving end according to the minimum number of the maximum cliques.

5. The method of claim 3, further comprising:

6. The method of claim 5, wherein the adjusting the mutual inductance coupling value of the transmitting end and the receiving end comprises:

and solving through a meta-heuristic algorithm, so as to select an array state which maximizes the received energy of the packet from the array states of the coil array, and taking the array state as the working state of the coil array at the transmitting end under the current time slice.

7. The method of claim 3, wherein after the sizes of the coils at the current charging receiving end and the current transmitting end of the charging system have been determined, the method further comprises: aiming at the self-adaptive processing process of the current of the sending terminal, the process is realized based on an ADMM algorithm.

8. A magnetic resonance charging system, includes sending end and receiving terminal, its characterized in that still includes:

the receiving end time slice distribution unit is used for determining a strong coupling receiving end pair with a mutual inductance coupling value exceeding a preset value according to mutual inductance coupling values among a plurality of receiving ends when the magnetic resonance charging system comprises the plurality of receiving ends: different charging time slices are respectively distributed to the receiving ends contained by the strong coupling receiving end, and the receiving ends only allow the receiving ends to charge in the time slices distributed to the receiving ends;

when the receiving end time slice allocation unit allocates charging time slices to one or more receiving ends, the mutual inductance coupling value of the sending end and the receiving end acquired by the mutual inductance coupling adjustment unit is the mutual inductance coupling value between the sending end and one receiving end which is charged by the current time slice; and energy transmission is carried out between the sending end and the receiving end based on the mutual inductance coupling value between the sending end and the receiving end which is adjusted by the mutual inductance coupling adjusting unit.