CN115995891A - Optimal working frequency determining method of multistage magnetic resonance wireless energy transmission system - Google Patents
Optimal working frequency determining method of multistage magnetic resonance wireless energy transmission system Download PDFInfo
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Abstract
The invention provides a method for determining the optimal working frequency of a multistage magnetic resonance wireless energy transmission system, wherein the method comprises the following steps: determining a plurality of candidate frequency points corresponding to zero transmitting loop phase according to the transmitting loop phase angle of the multi-stage magnetic resonance wireless energy transmission system and the change relation curve of the output loop current along with frequency and load; and selecting the candidate frequency point with the smallest relative change of the output loop current in a plurality of frequency ranges corresponding to the plurality of candidate frequency points as the optimal working frequency of the multistage magnetic resonance wireless energy transmission system. The invention solves the problem that the wireless power transmission device in the related technology cannot ensure constant current output due to frequency fluctuation.
Description
Technical Field
The invention relates to the field of wireless power supply, in particular to a method for determining the optimal working frequency of a multistage magnetic resonance wireless energy transmission system.
Background
The wireless power transmission technology mainly comprises three types: electromagnetic inductive coupling, magnetic resonant coupling, and microwave radiation. The magnetic coupling resonance type wireless power transmission technology is widely applied to the fields of rail transit, mobile phone charging and the like due to the advantages of safety, reliability, flexibility, stability and the like. The wireless power supply system realized by the technology can realize energy transmission without physical contact, so that the wireless power supply system is widely applied in scenes with high requirements such as long distance, large air gap and the like.
However, such circuits often require a larger size transmit coil and receive coil, waste materials and increase safety risks, adding multiple relay coils between the transmit coil and receive coil can solve the problem of oversized coils and increase energy transmission distances. However, the number of the coils is increased, so that the number of the resonant circuit loops is increased, the system characteristics become complex, the system is more sensitive to parameter changes, and the finding of the corresponding optimal working frequency of the system is particularly important. The multistage magnetic resonance wireless energy transmission system can cause unstable output current due to frequency deviation, and the effect of constant current output can not be ensured due to frequency fluctuation in the wireless energy transmission process. Therefore, the problem that the wireless power transmission device cannot guarantee constant current output due to frequency fluctuation exists in the prior art.
Disclosure of Invention
The invention provides an optimal working frequency determining method of a multistage magnetic resonance wireless energy transmission system, which at least solves the problem that a wireless electric energy transmission device cannot guarantee constant current output due to frequency fluctuation in the related technology.
According to a first aspect of an embodiment of the present invention, there is provided a method for determining an optimal operating frequency of a multi-stage magnetic resonance wireless energy transfer system, the method including: determining a plurality of candidate frequency points corresponding to zero transmitting loop phase according to the transmitting loop phase angle of the multi-stage magnetic resonance wireless energy transmission system and the change relation curve of the output loop current along with frequency and load; and selecting the candidate frequency point with the minimum relative change of the output loop current in a plurality of frequency ranges corresponding to the plurality of candidate frequency points as the optimal working frequency of the multistage magnetic resonance wireless energy transmission system.
Optionally, before determining the plurality of candidate frequency points corresponding to zero of the transmission loop phase according to the transmission loop phase angle and the variation relation curve of the output loop current with the frequency and the load of the multi-stage magnetic resonance wireless energy transmission system, the method further comprises: establishing a circuit model according to a decoupling equivalent circuit corresponding to the multilevel magnetic resonance wireless energy transmission system by adopting an electrical law; determining expressions of input current and input impedance of a two-port network corresponding to the multi-stage magnetic resonance wireless energy transmission system according to the circuit model based on the two-port network correlation law; and determining that the constant current frequency of the multistage magnetic resonance wireless energy transmission system is equal to the zero phase angle frequency of the transmitting loop according to the expression of the input current and the input impedance.
Optionally, the method further comprises: and changing the working frequency of the multi-stage magnetic resonance wireless energy transmission system by utilizing a circuit model through a frequency sweep method to obtain a change relation curve of the phase angle of a transmitting loop and the current of an output loop of the multi-stage magnetic resonance wireless energy transmission system along with the frequency and the load.
Optionally, the method further comprises: establishing a time domain differential model corresponding to the multistage magnetic resonance wireless energy transmission system; and verifying whether the phase angles of the current and the voltage of the transmitting loop of the multistage magnetic resonance wireless energy transmission system are zero under the optimal working frequency according to the time domain differential model.
Optionally, the system output loop current is not affected by the equivalent load of the output loop when the system is at the candidate frequency point.
Optionally, the transmit loop phase relative change for the candidate frequency point when the output loop current relative change is minimal is also minimal.
According to a second aspect of the embodiment of the present invention, there is also provided an optimum operating frequency determining apparatus for a multistage magnetic resonance wireless energy transfer system, the apparatus comprising: the first determining module is used for determining a plurality of candidate frequency points corresponding to zero transmitting loop phase according to the transmitting loop phase angle of the multi-stage magnetic resonance wireless energy transmission system and the change relation curve of the output loop current along with frequency and load; and the selecting module is used for selecting the candidate frequency point with the smallest relative change of the output loop current in a plurality of frequency ranges corresponding to the plurality of candidate frequency points as the optimal working frequency of the multistage magnetic resonance wireless energy transmission system.
Optionally, the decoupling equivalent circuit of the multi-stage magnetic resonance wireless energy transfer system comprises: the transmitting loop, a plurality of relay coils and the output loop are connected in sequence; the transmitting loop, the plurality of relay coils and the output loop are all S-shaped resonance compensation circuits, the transmitting loop further comprises a direct current power supply, and the output loop further comprises a rectifier and an equivalent load of a direct current resistor.
Optionally, the apparatus further comprises: the first building module is used for building a circuit model according to a decoupling equivalent circuit corresponding to the multi-stage magnetic resonance wireless energy transmission system by adopting an electricity law; the second determining module is used for determining an expression of input current and input impedance of the two-port network corresponding to the multi-level magnetic resonance wireless energy transmission system according to the two-port network correlation law; and the third determining module is used for determining that the constant current frequency of the multistage magnetic resonance wireless energy transmission system is equal to the zero phase angle frequency of the transmitting loop according to the expression of the input current and the input impedance.
Optionally, the apparatus further comprises: the obtaining module is used for obtaining a transmission loop phase angle and an output loop current change relation curve of the multistage magnetic resonance wireless energy transmission system along with frequency and load by changing the working frequency of the multistage magnetic resonance wireless energy transmission system through a frequency sweep method by utilizing the circuit model.
Optionally, the apparatus further comprises: the second building module is used for building a time domain differential model corresponding to the multistage magnetic resonance wireless energy transmission system; and the verification module is used for verifying whether the current and voltage phase angles of the transmitting loop of the multistage magnetic resonance wireless energy transmission system are zero under the optimal working frequency according to the time domain differential model.
Optionally, the system output loop current is not affected by the equivalent load of the output loop when the system is at the candidate frequency point.
Optionally, the transmit loop phase relative change for the candidate frequency point when the output loop current relative change is minimal is also minimal.
According to a third aspect of the embodiment of the present invention, there is also provided an electronic device including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory complete communication with each other through the communication bus; wherein the memory is used for storing a computer program; a processor for performing the method steps of any of the embodiments described above by running the computer program stored on the memory.
According to a fourth aspect of embodiments of the present invention, there is also provided a computer-readable storage medium having stored therein a computer program, wherein the computer program is arranged to perform the method steps of any of the embodiments described above when run.
In the embodiment of the invention, a plurality of candidate frequency points corresponding to zero transmitting loop phase are determined according to the transmitting loop phase angle of the multi-stage magnetic resonance wireless energy transmission system and the change relation curve of the output loop current along with frequency and load; and selecting the candidate frequency point with the smallest relative change of the output loop current in a plurality of frequency ranges corresponding to the plurality of candidate frequency points as the optimal working frequency of the multistage magnetic resonance wireless energy transmission system. The invention determines a plurality of candidate frequency points through a curve obtained by simulation, selects the candidate frequency point with the least influence on output current by frequency change as the optimal working frequency, achieves the effects of maintaining stable output of the system, reducing reactive power of the system and improving the efficiency of the system, and solves the problem that the constant current output of the wireless power transmission device cannot be ensured due to frequency fluctuation in the related technology.
In the embodiment of the invention, a time domain differential model corresponding to a multistage magnetic resonance wireless energy transmission system is established; according to the time domain differential model, whether the phase angle of the current and the voltage of the transmitting loop is zero or not is verified by the system under the optimal working frequency, and the effect of enabling the system to recover the resonance state can be achieved by adjusting the optimal working frequency after the frequency of the system is shifted, so that verification of the effectiveness of the optimal working frequency is achieved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort.
FIG. 1 is a schematic diagram of a hardware environment for an alternative method of determining an optimal operating frequency for a multi-stage magnetic resonance wireless energy transfer system in accordance with an embodiment of the present invention;
FIG. 2 is a flow chart of an alternative method of determining an optimal operating frequency of a multi-stage magnetic resonance wireless energy transfer system in accordance with an embodiment of the present invention;
FIG. 3 is a schematic circuit diagram of a multi-stage magnetic resonance wireless energy transfer system in accordance with an embodiment of the present invention;
FIG. 4a is a graph of the transmit loop phase angle versus frequency and load for a multi-stage magnetic resonance wireless energy transfer system in accordance with an embodiment of the present invention;
FIG. 4b is a graph of output loop current versus frequency and load for a multi-stage magnetic resonance wireless energy transfer system in accordance with an embodiment of the present invention;
FIG. 5a is a plot of phase and frequency around 195.8kHz in accordance with an embodiment of the invention;
FIG. 5b is a graph of output loop current versus frequency around 195.8kHz in accordance with an embodiment of the invention;
FIG. 6a is a plot of phase and frequency around a 210.7kHz frequency in accordance with an embodiment of the invention;
FIG. 6b is a graph of output loop current versus frequency around a 210.7kHz frequency in accordance with an embodiment of the invention;
FIG. 7a is a schematic diagram of a time-domain differential model corresponding to a multi-stage magnetic resonance wireless energy transfer system according to an embodiment of the present invention;
FIG. 7b is a simulated waveform of input voltage and input current when the transmitting side of the multi-stage magnetic resonance wireless energy transfer system is not resonating in accordance with an embodiment of the present invention;
FIG. 7c is a simulated waveform of input voltage and input current when the transmitting side of the multi-stage magnetic resonance wireless energy transfer system resonates according to an embodiment of the present invention;
FIG. 8 is a block diagram of an alternative multi-stage magnetic resonance wireless power transfer system optimum operating frequency determination apparatus in accordance with an embodiment of the present invention;
FIG. 9 is a schematic diagram of a decoupling equivalent circuit of a multi-stage magnetic resonance wireless energy transfer system in accordance with an embodiment of the present invention;
fig. 10 is a block diagram of an alternative electronic device in accordance with an embodiment of the present invention.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
It should be noted that in the description of the present invention, the terms "first," "second," and the like are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus. The terms "mounted," "connected," "coupled," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; the two components can be directly connected or indirectly connected through an intermediate medium, or can be communicated inside the two components, or can be connected wirelessly or in a wired way. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
According to one aspect of the embodiment of the invention, an optimal operating frequency determination method of a multi-stage magnetic resonance wireless energy transfer system is provided. Alternatively, in the present embodiment, the above-described method for determining the optimal operating frequency of the multi-stage magnetic resonance wireless power transmission system may be applied to a hardware environment as shown in fig. 1. As shown in fig. 1, the terminal 102 may include a memory 104, a processor 106, and a display 108 (optional components). The terminal 102 may be communicatively coupled to a server 112 via a network 110, the server 112 being operable to provide services (e.g., application services, etc.) to the terminal or to clients installed on the terminal, and a database 114 may be provided on the server 112 or independent of the server 112 for providing data storage services to the server 112. In addition, a processing engine 116 may be run in the server 112, which processing engine 116 may be used to perform the steps performed by the server 112.
Alternatively, the terminal 102 may be, but is not limited to, a terminal capable of calculating data, such as a mobile terminal (e.g., a mobile phone, a tablet computer), a notebook computer, a PC (Personal Computer ) or the like, which may include, but is not limited to, a wireless network or a wired network. Wherein the wireless network comprises: bluetooth, WIFI (Wireless Fidelity ) and other networks that enable wireless communications. The wired network may include, but is not limited to: wide area network, metropolitan area network, local area network. The server 112 may include, but is not limited to, any hardware device that can perform calculations.
In addition, in this embodiment, the method for determining the optimal operating frequency of the multi-stage magnetic resonance wireless energy transmission system may be applied to, but not limited to, an independent processing device with a relatively high processing capability, without data interaction. For example, the processing device may be, but is not limited to being, a more powerful terminal device, i.e., the operations of the method for determining the optimal operating frequency of the multi-stage magnetic resonance wireless energy transfer system described above may be integrated into a single processing device. The above is merely an example, and is not limited in any way in the present embodiment.
Alternatively, in the present embodiment, the method for determining the optimal operating frequency of the multi-stage magnetic resonance wireless energy transmission system may be performed by the server 112, by the terminal 102, or by both the server 112 and the terminal 102. The method for determining the optimal operating frequency of the multi-stage magnetic resonance wireless energy transmission system implemented by the terminal 102 according to the embodiment of the present invention may also be implemented by a client installed thereon.
Taking an example that the optimal operating frequency determining method of the multi-stage magnetic resonance wireless energy transmission system is applied to the central processing unit, fig. 2 is a schematic flow chart of an optional optimal operating frequency determining method of the multi-stage magnetic resonance wireless energy transmission system according to an embodiment of the present invention, as shown in fig. 2, the flow chart of the method may include the following steps:
step S201, determining a plurality of candidate frequency points corresponding to zero transmitting loop phase according to the transmitting loop phase angle and the output loop current change relation curve of the multi-stage magnetic resonance wireless energy transmission system along with frequency and load. Optionally, fig. 3 is a schematic circuit diagram of a multi-stage magnetic resonance wireless energy transmission system according to an embodiment of the present invention, where the multi-stage magnetic resonance wireless energy transmission system is also referred to as a system hereinafter, and the schematic circuit diagram sequentially includes a transmitting loop, a plurality of relay coils, and a receiving loop of the system from left to right. Wherein the transmitting loop comprises a direct current power supply V dc Will direct current power V dc System inversion link S for converting into alternating voltage 1 -S 4 Resonance capacitor C 1 Resonant inductance L 1 Internal resistance R of resonant inductor 1 The method comprises the steps of carrying out a first treatment on the surface of the Each relay coil comprises a resonant capacitor, a resonant inductor and resonant inductor internal resistance; the receiving loop comprises a resonant capacitor C n Resonant inductance L n Internal resistance R of resonant inductor n Rectifying element D for converting alternating current into direct current 1 -D 4 Filter capacitor C f And an equivalent load R. M is the same as that of the prior art 12 -M (n-1)n For mutual inductance between the coils, the coils are coupled to each other. Coil number, resonant inductance, resonant capacitance, inductance internal resistance and output in a given multistage magnetic resonance wireless energy transfer systemWhen the loop equivalent load and other parameters are specific, the change relation curve of the phase angle of the transmitting loop and the change relation curve of the current of the output loop and the frequency of the transmitting loop of the multi-stage magnetic resonance wireless energy transmission system in fig. 4a and 4b can be obtained, and the change relation curve of the phase angle of the transmitting loop and the change relation curve of the current of the output loop and the frequency of the multi-stage magnetic resonance wireless energy transmission system in fig. 4a and 4b can be formed together. And searching a plurality of frequency points corresponding to zero phase of the transmitting loop according to the change relation curve to serve as candidate frequency points of the optimal working frequency of the system, wherein the candidate frequency points are resonance frequency points enabling each coil of the system to resonate. As shown in fig. 4a, there are two candidate frequency points, f1= 195.8kHz and f2=210.7 kHz, respectively.
Step S202, selecting a candidate frequency point with the minimum relative change of the output loop current in a plurality of frequency ranges corresponding to the plurality of candidate frequency points as the optimal working frequency of the multi-stage magnetic resonance wireless energy transmission system. Optionally, when the operating frequency of the system changes around the candidate frequency point f1 or f2, the transmit loop phase angle and the output loop current will also change accordingly. Specifically, fig. 5a and 5b show the change in the phase angle of the transmit loop, i.e., fig. 5a, and the change in the output loop current, i.e., fig. 5b, when the system operating frequency changes around f1= 195.8 kHz. In this embodiment, the system has 5 coils (one transmitting loop, three relay coils, and one receiving loop), so I5 corresponds to the output loop current. Similarly, fig. 6a and 6b show the change in transmit loop phase angle and output loop current when the system operating frequency is changed around f2=210.7 kHz. Table 1 is a table of the phase angle of the transmitting loop and the current change of the output loop, and the candidate frequency point, f2=210.7khz, with the smallest relative change of the current of the output loop is selected as the optimal working frequency of the multistage magnetic resonance wireless energy transmission system.
Table 1 transmit loop phase angle and output loop current change meter
In the embodiment of the invention, a plurality of candidate frequency points corresponding to zero transmitting loop phase are determined according to the transmitting loop phase angle of the multi-stage magnetic resonance wireless energy transmission system and the change relation curve of the output loop current along with frequency and load; and selecting the candidate frequency point with the smallest relative change of the output loop current in a plurality of frequency ranges corresponding to the plurality of candidate frequency points as the optimal working frequency of the multistage magnetic resonance wireless energy transmission system. The invention determines a plurality of candidate frequency points through a curve obtained by simulation, selects the candidate frequency point with the least influence on output current by frequency change as the optimal working frequency, achieves the effects of maintaining stable output of the system, reducing reactive power of the system and improving the efficiency of the system, and solves the problem that the constant current output of the wireless power transmission device cannot be ensured due to frequency fluctuation in the related technology.
As an alternative embodiment, the transmit loop phase relative change for the candidate frequency point where the output loop current relative change is minimal is also minimal. Alternatively, f2=210.7 kHz in table 1 is the candidate frequency point at which the relative change of the output loop current is minimal, at which time the relative change of the transmit loop phase angle is [ -12.5 °,4.8 ° ], the relative change of the transmit loop phase angle is 138.4%, which is the minimum relative change of the transmit loop phase angle in all candidate frequency points, and the minimum relative change of the output loop current is consistent. In the embodiment of the invention, the optimal working frequency of the system is obtained by selecting proper frequency to make the system least sensitive to the change of the frequency parameter.
As an alternative embodiment, before determining a plurality of candidate frequency points corresponding to zero transmit loop phase according to the transmit loop phase angle and the output loop current versus frequency and load curve of the multi-stage magnetic resonance wireless energy transfer system, the method further comprises: establishing a circuit model according to a decoupling equivalent circuit corresponding to the multilevel magnetic resonance wireless energy transmission system by adopting an electrical law; determining expressions of input currents and input impedances of a two-port network corresponding to the multi-stage magnetic resonance wireless energy transmission system according to a circuit model based on a two-port network correlation law; and determining that the constant current frequency of the multistage magnetic resonance wireless energy transmission system is equal to the zero phase angle frequency of the transmitting loop according to the expression of the input current and the input impedance.
Optionally, the circuit of the multi-stage magnetic resonance wireless energy transmission system shown in fig. 3 is decoupled and equivalent before the circuit model is built, that is, only the switching link is considered at the power supply end and the load end, and only the electromagnetic coupling link is considered at the intermediate coil. Then, a circuit model, namely a column writing equation set, is built for a decoupling equivalent circuit of the multi-stage magnetic resonance wireless energy transmission system according to the kirchhoff voltage law and the kirchhoff current law:
in the method, in the process of the invention,
C 1 -C n for the resonance capacitance of the respective coils, L 1 -L n For the resonance inductance of the respective coils, R 1 -R n For the internal resistance of the resonance inductance of each coil, M 12 -M (n-1)n For the mutual inductance between the individual coils,
for the current vector of the respective coil +.>
Is the voltage vector of each coil.
For ease of analysis, the coils in the system are of the same size, i.e. the resonance capacitance and resonance inductance of each coil are equal:
L i ＝L(i＝1,2,…,n)
C i ＝C(i＝1,2,…,n)
simultaneously, the coil is evenly arranged, namely:
at this time, the above circuit model can be simplified as:
in the method, in the process of the invention,
representing the coupling coefficient between the ith and jth coils, the reduced matrix (circuit model) is a real symmetric matrix, which is further reduced, and the first and last rows of the deleted matrix form a new matrix:
dividing the matrix into three partitioned matrices of a transmitting loop, a relay coil and an output loop according to parameter properties:
wherein alpha, beta, gamma,
Respectively represent:
α＝[-k 12 -k 13 …-k 1(n-1) ] T
β＝[-k 1(n-1) -k 1(n-2) …-k 12 ] T
the two-port network correlation law is used for the above circuit model, wherein the two-port network is a circuit or device with 2 ports, and the ports are connected with the internal network of the circuit. One port is composed of 2 terminals, and when the 2 terminals satisfy the port condition that the current flowing in one terminal is equal to the current flowing out of the other terminal, the 2 terminals constitute one port, in other words, the same current flows in and out of the same port, that is, the input current at the port is equal to the output current. The two-port network can represent the whole or a part of the circuit by the corresponding external characteristic parameters without considering the specific conditions inside the circuit, so that the represented circuit becomes a black box with a group of special properties, thereby achieving the purposes of simplifying analysis and abstracting the physical composition of the circuit. Input current of two-port network corresponding to the circuit model
And input impedance Z in The expression of (2) is:
wherein, each impedance is respectively:
Z 12 ＝jωL(k 1n +α T γ -1 β)
Z 21 ＝Z 12
for systems for determining parameters, e.g. when Z 11 When=0, the system output current and input impedance can be expressed as:
at this time, the output current is equal to the input voltage only
And impedance Z 12 In relation to the input impedance Z in With load R only L And impedance Z 12 When the system parameter is given, the input impedance is a determined value, and the system output constant current characteristic and the transmitting loop zero phase angle characteristic are simultaneously present, namely the transmitting loop zero phase angle frequency point and the constant current frequency point of the system are the same. In the embodiment of the invention, a conclusion that the constant current frequency of the multistage magnetic resonance wireless energy transmission system is equal to the zero phase angle frequency of the transmitting loop is obtained by establishing a circuit model to deduce and analyze. And a theoretical basis is laid for determining candidate frequency points and verifying optimal working frequency according to the phase angle of the transmitting loop.
As an alternative embodiment, the method further comprises: and changing the working frequency of the multi-stage magnetic resonance wireless energy transmission system by utilizing a circuit model through a frequency sweep method to obtain a change relation curve of the phase angle of a transmitting loop and the current of an output loop of the multi-stage magnetic resonance wireless energy transmission system along with the frequency and the load. Optionally, a circuit model corresponding to the multistage magnetic resonance wireless energy transmission system is established, corresponding parameters of the system are changed by using a frequency sweep step to change the working frequency, and therefore a change relation curve of a phase angle of a transmitting loop and a current of an output loop along with the frequency and the load is obtained. In particular, the dependence includes a dependence of the transmit loop phase angle with frequency and load as shown in fig. 4a and a dependence of the output loop current with frequency and load as shown in fig. 4 b.
As an alternative embodiment, the method further comprises: establishing a time domain differential model corresponding to the multistage magnetic resonance wireless energy transmission system; and verifying whether the phase angles of the current and the voltage of the transmitting loop of the multistage magnetic resonance wireless energy transmission system are zero under the optimal working frequency according to the time domain differential model. Optionally, fig. 7a is a schematic diagram of a time-domain differential model constructed according to a multi-stage magnetic resonance wireless energy transmission system of a transmitting loop, three relay coils and an output loop, wherein s1, s2, s3 and s4 are pulse signals for controlling the inverter to work, and by changing parameters in the time-domain differential model in simulation software, simulation results of an input voltage U1 and an input current I1 of the system when the system frequency is 200kHz are obtained, as shown in fig. 7b, at this time, the transmitting side, i.e., the transmitting loop, is in a non-resonant state and the current phase and the voltage phase differ by θ=6.16 °. Fig. 7c is a simulation result of the input voltage and the input current of the system after the system operating frequency is adjusted to the optimal operating frequency, where the transmitting side is in a resonant state and the current phase and the voltage phase differ by θ=0°. In the embodiment of the invention, the time-domain differential model is established through simulation software to carry out experimental verification on the optimal working frequency point of the system, so that the reliability of the conclusion is improved.
As an alternative embodiment, the system output loop current is not affected by the equivalent load of the output loop when the system is at the candidate frequency point. Optionally, fig. 4b is a graph showing the relationship between the output loop current of the system and the frequency and the load, in which different curves respectively correspond to the relationship between the output loop current and the frequency under different output loop equivalent loads RL, and the curves intersect at f1 and f2, that is, the output loop current of the system is the same value regardless of the value of the load RL, so that when the system is at the candidate frequency point, the output loop current of the system is not affected by the equivalent load of the output loop.
According to another aspect of the embodiment of the invention, an optimal operating frequency determining device of the multi-stage magnetic resonance wireless energy transmission system is also provided. FIG. 8 is a block diagram of an alternative apparatus for determining an optimal operating frequency for a multi-stage magnetic resonance wireless power transfer system in accordance with an embodiment of the present invention, as shown in FIG. 8, the apparatus may include: the first determining module 801 is configured to determine a plurality of candidate frequency points corresponding to when the phase of the transmitting loop is zero according to a phase angle of the transmitting loop of the multi-stage magnetic resonance wireless energy transfer system and a variation relationship curve of the output loop current with frequency and load; the selecting module 802 is configured to select, as an optimal operating frequency of the multi-stage magnetic resonance wireless energy transfer system, a candidate frequency point with a minimum output loop current relative change in a plurality of frequency ranges corresponding to the plurality of candidate frequency points.
It should be noted that, the first determining module 801 in this embodiment may be configured to perform the step S201, and the selecting module 802 may be configured to perform the step S202.
Through the module, a plurality of candidate frequency points are determined, the candidate frequency point with the least influence of frequency change on output current is selected as the optimal working frequency, the effects of maintaining stable output of the system, reducing reactive power of the system and improving the efficiency of the system are achieved, and the problem that the constant current output of the wireless power transmission device cannot be ensured due to frequency fluctuation in the related technology is solved.
As an alternative embodiment, the decoupling equivalent circuit of the multi-stage magnetic resonance wireless energy transfer system comprises: the transmitting loop, a plurality of relay coils and the output loop are connected in sequence; the transmitting loop, the plurality of relay coils and the output loop are all S-shaped resonance compensation circuits, the transmitting loop further comprises a direct current power supply, and the output loop further comprises a rectifier and an equivalent load of a direct current resistor. Optionally, FIG. 9 is a schematic diagram of a decoupling equivalent circuit of the multi-stage magnetic resonance wireless energy transfer system of FIG. 3, in which only the switching element is considered at both the power supply and load ends, and only the electromagnetic coupling element, namely M, is considered at the intermediate coil 12 -M (n-1)n . The device comprises a transmitting loop, a plurality of relay coils and an output loop from left to right, wherein the transmitting loop comprises a direct current power supply, and the voltage at two ends is u 1 The output loop comprises a rectifier and an equivalent load R of a direct current resistor L The transmitting loop, the plurality of relay coils and the output loop are all S-shaped resonance compensation circuits, namely the inductance L i Electric powerR resistance i And capacitor C i And a series resonance compensation circuit. In the embodiment of the invention, the transmission distance can be prolonged on the premise of ensuring the system efficiency or power by properly adding the resonant coil as a repeater between the transmitting loop and the receiving loop. It should be noted that, the repeater is composed of a resonant capacitor and a resonant inductor, so that when the system works at a resonant frequency (ωl=1/ωc), the condition that the magnetic field strength of the transmission channel is enhanced by adding the repeater coil can be met, and if and only when the system works at the resonant frequency, the energy transmission efficiency between the coils is highest.
As an alternative embodiment, the apparatus further comprises: the first building module is used for building a circuit model according to a decoupling equivalent circuit corresponding to the multi-stage magnetic resonance wireless energy transmission system by adopting an electricity law; the second determining module is used for determining an expression of input current and input impedance of the two-port network corresponding to the multi-stage magnetic resonance wireless energy transmission system according to the circuit model based on the two-port network correlation law; and the third determining module is used for determining that the constant current frequency of the multistage magnetic resonance wireless energy transmission system is equal to the zero phase angle frequency of the transmitting loop according to the expressions of the input current and the input impedance.
As an alternative embodiment, the apparatus further comprises: the obtaining module is used for obtaining a transmission loop phase angle and an output loop current change relation curve of the multistage magnetic resonance wireless energy transmission system along with frequency and load by changing the working frequency of the multistage magnetic resonance wireless energy transmission system through a frequency sweep method by utilizing the circuit model.
As an alternative embodiment, the apparatus further comprises: the second building module is used for building a time domain differential model corresponding to the multistage magnetic resonance wireless energy transmission system; and the verification module is used for verifying whether the phase angles of the current and the voltage of the transmitting loop of the multistage magnetic resonance wireless energy transmission system are zero under the optimal working frequency according to the time domain differential model.
As an alternative embodiment, the system output loop current is not affected by the equivalent load of the output loop when the system is at the candidate frequency point.
As an alternative embodiment, the transmit loop phase relative change for the candidate frequency point where the output loop current relative change is minimal is also minimal.
It should be noted that the above modules are the same as examples and application scenarios implemented by the corresponding steps, but are not limited to what is disclosed in the above embodiments. It should be noted that the above modules may be implemented in software or in hardware as part of the apparatus shown in fig. 1, where the hardware environment includes a network environment.
According to still another aspect of the embodiments of the present invention, there is also provided an electronic device, which may be a server, a terminal, or a combination thereof, for implementing the method for determining an optimal operating frequency of the above-described multi-stage magnetic resonance wireless energy transfer system.
Fig. 10 is a block diagram of an alternative electronic device according to an embodiment of the present invention, as shown in fig. 10, including a processor 1001, a communication interface 1002, a memory 1003, and a communication bus 1004, wherein the processor 1001, the communication interface 1002, and the memory 1003 perform communication with each other through the communication bus 1004, and wherein the memory 1003 is configured to store a computer program; the processor 1001 is configured to execute a computer program stored in the memory 1003, and perform the following steps:
determining a plurality of candidate frequency points corresponding to zero transmitting loop phase according to the transmitting loop phase angle of the multi-stage magnetic resonance wireless energy transmission system and the change relation curve of the output loop current along with frequency and load; and selecting the candidate frequency point with the smallest relative change of the output loop current in a plurality of frequency ranges corresponding to the plurality of candidate frequency points as the optimal working frequency of the multistage magnetic resonance wireless energy transmission system.
Alternatively, in the present embodiment, the above-described communication bus may be a PCI (Peripheral Component Interconnect, peripheral component interconnect standard) bus, or an EISA (Extended Industry Standard Architecture ) bus, or the like. The communication bus may be classified as an address bus, a data bus, a control bus, or the like. For ease of illustration, only one thick line is shown in fig. 10, but not only one bus or one type of bus.
The communication interface is used for communication between the electronic device and other devices.
The memory may include RAM or may include non-volatile memory (non-volatile memory), such as at least one disk memory. Optionally, the memory may also be at least one memory device located remotely from the aforementioned processor.
As an example, as shown in fig. 10, the memory 1003 may include, but is not limited to, a first determining module 801 and a selecting module 802 in an optimal operating frequency determining apparatus of the multi-stage magnetic resonance wireless energy transfer system. In addition, other module units in the optimal operating frequency determining device of the multi-stage magnetic resonance wireless energy transmission system may be included, but are not limited to, and are not described in detail in this example.
The processor may be a general purpose processor and may include, but is not limited to: CPU (Central Processing Unit ), NP (Network Processor, network processor), etc.; but also DSP (Digital Signal Processing, digital signal processor), ASIC (Application Specific Integrated Circuit ), FPGA (Field-Programmable Gate Array, field programmable gate array) or other programmable logic device, discrete gate or transistor logic device, discrete hardware components.
In addition, the electronic device further includes: and the display is used for displaying the optimal working frequency determination result of the multi-stage magnetic resonance wireless energy transmission system.
Alternatively, specific examples in this embodiment may refer to examples described in the foregoing embodiments, and this embodiment is not described herein.
It will be understood by those skilled in the art that the structure shown in fig. 10 is only schematic, and the device implementing the method for determining the optimal operating frequency of the multi-stage magnetic resonance wireless energy transmission system may be a terminal device, and the terminal device may be a smart phone (such as an Android mobile phone, an iOS mobile phone, etc.), a tablet computer, a palm computer, a mobile internet device (Mobile Internet Devices, MID), a PAD, etc. Fig. 10 does not limit the structure of the electronic device. For example, the terminal device may also include more or fewer components (e.g., network interfaces, display devices, etc.) than shown in fig. 10, or have a different configuration than shown in fig. 10.
Those of ordinary skill in the art will appreciate that all or part of the steps in the various methods of the above embodiments may be implemented by a program for instructing a terminal device to execute in association with hardware, the program may be stored in a computer readable storage medium, and the storage medium may include: flash disk, ROM, RAM, magnetic or optical disk, etc.
According to yet another aspect of an embodiment of the present invention, there is also provided a storage medium. Alternatively, in the present embodiment, the above-described storage medium may be used for executing the program code of the optimal operating frequency determining method of the multi-stage magnetic resonance wireless power transmission system.
Alternatively, in this embodiment, the storage medium may be located on at least one network device of the plurality of network devices in the network shown in the above embodiment.
Alternatively, in the present embodiment, the storage medium is configured to store program code for performing the steps of:
determining a plurality of candidate frequency points corresponding to zero transmitting loop phase according to the transmitting loop phase angle of the multi-stage magnetic resonance wireless energy transmission system and the change relation curve of the output loop current along with frequency and load; and selecting the candidate frequency point with the smallest relative change of the output loop current in a plurality of frequency ranges corresponding to the plurality of candidate frequency points as the optimal working frequency of the multistage magnetic resonance wireless energy transmission system.
Alternatively, specific examples in the present embodiment may refer to examples described in the above embodiments, which are not described in detail in the present embodiment.
Alternatively, in the present embodiment, the storage medium may include, but is not limited to: various media capable of storing program codes, such as a U disk, ROM, RAM, a mobile hard disk, a magnetic disk or an optical disk.
The foregoing embodiment numbers of the present invention are merely for the purpose of description, and do not represent the advantages or disadvantages of the embodiments. In the foregoing embodiments of the present invention, the descriptions of the embodiments are emphasized, and for a portion of this disclosure that is not described in detail in this embodiment, reference is made to the related descriptions of other embodiments.
In several embodiments provided by the present invention, it should be understood that the disclosed client may be implemented in other manners. The above-described embodiments of the apparatus are merely exemplary, and are merely a logical functional division, and there may be other manners of dividing the apparatus in actual implementation, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be through some interfaces, units or modules, or may be in electrical or other forms.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution provided in the present embodiment.
In addition, each functional unit in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (10)
1. A method for determining an optimal operating frequency of a multi-stage magnetic resonance wireless energy transfer system, the method comprising:
determining a plurality of candidate frequency points corresponding to zero transmitting loop phase according to the transmitting loop phase angle of the multi-stage magnetic resonance wireless energy transmission system and the change relation curve of the output loop current along with frequency and load;
and selecting the candidate frequency point with the minimum relative change of the output loop current in a plurality of frequency ranges corresponding to the plurality of candidate frequency points as the optimal working frequency of the multistage magnetic resonance wireless energy transmission system.
2. The method of claim 1, wherein before determining the plurality of candidate frequency points corresponding to zero transmit loop phase according to the transmit loop phase angle and the output loop current versus frequency and load curve of the multi-stage magnetic resonance wireless energy transfer system, the method further comprises:
establishing a circuit model according to a decoupling equivalent circuit corresponding to the multilevel magnetic resonance wireless energy transmission system by adopting an electrical law;
determining expressions of input current and input impedance of a two-port network corresponding to the multi-stage magnetic resonance wireless energy transmission system according to the circuit model based on the two-port network correlation law;
and determining that the constant current frequency of the multistage magnetic resonance wireless energy transmission system is equal to the zero phase angle frequency of the transmitting loop according to the expression of the input current and the input impedance.
3. The method of determining an optimal operating frequency for a multi-stage magnetic resonance wireless energy transfer system of claim 2, further comprising:
and changing the working frequency of the multi-stage magnetic resonance wireless energy transmission system by utilizing a circuit model through a frequency sweep method to obtain a change relation curve of the phase angle of a transmitting loop and the current of an output loop of the multi-stage magnetic resonance wireless energy transmission system along with the frequency and the load.
4. The method of determining an optimal operating frequency for a multi-stage magnetic resonance wireless energy transfer system of claim 1, further comprising:
establishing a time domain differential model corresponding to the multistage magnetic resonance wireless energy transmission system;
and verifying whether the phase angles of the current and the voltage of the transmitting loop of the multistage magnetic resonance wireless energy transmission system are zero under the optimal working frequency according to the time domain differential model.
5. The method for determining the optimal operating frequency of a multi-stage magnetic resonance wireless energy transfer system of claim 1, wherein the system output loop current is not affected by the equivalent load of the output loop when the system is at a candidate frequency point.
6. The method for determining the optimal operating frequency of a multi-stage magnetic resonance wireless energy transfer system of claim 1, wherein the transmit loop phase relative change for the candidate frequency point at which the output loop current relative change is minimal is also minimal.
7. An optimal operating frequency determining device for a multi-stage magnetic resonance wireless energy transfer system, the device comprising:
the first determining module is used for determining a plurality of candidate frequency points corresponding to zero transmitting loop phase according to the transmitting loop phase angle of the multi-stage magnetic resonance wireless energy transmission system and the change relation curve of the output loop current along with frequency and load;
and the selecting module is used for selecting the candidate frequency point with the smallest relative change of the output loop current in a plurality of frequency ranges corresponding to the plurality of candidate frequency points as the optimal working frequency of the multistage magnetic resonance wireless energy transmission system.
8. The optimal operating frequency determining apparatus of a multi-stage magnetic resonance wireless power transfer system of claim 7, wherein the decoupling equivalent circuit of the multi-stage magnetic resonance wireless power transfer system comprises: the transmitting loop, a plurality of relay coils and the output loop are connected in sequence;
the transmitting loop, the plurality of relay coils and the output loop are all S-shaped resonance compensation circuits, the transmitting loop further comprises a direct current power supply, and the output loop further comprises a rectifier and an equivalent load of a direct current resistor.
9. An electronic device comprising a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus, characterized in that,
the memory is used for storing a computer program;
the processor is configured to perform the method steps of any of claims 1 to 6 by running the computer program stored on the memory.
10. A computer-readable storage medium, characterized in that the storage medium has stored therein a computer program, wherein the computer program, when executed by a processor, implements the method steps of any of claims 1 to 6.
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