Method for determining optimal operating frequency of multi-stage magnetic resonance wireless power transmission system

Abstract

This invention provides a method for determining the optimal operating frequency of a multi-stage magnetic resonant wireless power transfer system. The method includes: determining multiple candidate frequency points corresponding to a zero phase angle of the transmitting circuit based on the phase angle of the transmitting circuit and the curves showing the relationship between the output circuit current and frequency and load; and selecting the candidate frequency point with the smallest relative change in output circuit current within multiple frequency ranges corresponding to the multiple candidate frequency points as the optimal operating frequency of the multi-stage magnetic resonant wireless power transfer system. This invention solves the problem in related technologies where wireless power transmission devices cannot guarantee constant current output due to frequency fluctuations.

Description

Technical Field

[0001] This invention relates to the field of wireless power supply, and in particular to a method for determining the optimal operating frequency of a multi-stage magnetic resonant wireless power transmission system. Background Technology

[0002] There are three main types of wireless power transfer technologies: electromagnetic induction coupling, magnetic resonant coupling, and microwave radiation. Among them, magnetically coupled resonant wireless power transfer technology is widely used in rail transportation, mobile phone charging, and other fields due to its advantages such as safety, reliability, flexibility, and stability. Wireless power supply systems based on this technology can transfer energy without physical contact, making them widely applicable in demanding scenarios such as long distances and atmospheric gaps.

[0003] However, such circuits often require large transmitting and receiving coils, wasting materials and increasing safety risks. Adding multiple relay coils between the transmitting and receiving coils can solve the problem of excessive coil size and increase the energy transmission distance. However, the increased number of coils leads to an increased number of resonant circuit loops, making the system characteristics more complex and sensitive to parameter changes. Finding the optimal operating frequency for the system becomes particularly important. Multi-stage magnetic resonant wireless power transmission systems suffer from unstable output current due to frequency shifts, making it impossible to guarantee constant current output during wireless power transmission. Therefore, existing wireless power transmission devices suffer from the problem of not being able to guarantee constant current output due to frequency fluctuations. Summary of the Invention

[0004] This invention provides a method for determining the optimal operating frequency of a multi-stage magnetic resonant wireless power transmission system, in order to at least solve the problem in related technologies where wireless power transmission devices cannot guarantee constant current output due to frequency fluctuations.

[0005] According to a first aspect of the present invention, a method for determining the optimal operating frequency of a multi-stage magnetic resonant wireless power transfer system is provided. The method includes: determining multiple candidate frequency points corresponding to a zero phase angle of the transmitting circuit based on the relationship curves of the phase angle of the transmitting circuit and the output circuit current as a function of frequency and load of the multi-stage magnetic resonant wireless power transfer system; and selecting the candidate frequency point with the smallest relative change in output circuit current within multiple frequency ranges corresponding to the multiple candidate frequency points as the optimal operating frequency of the multi-stage magnetic resonant wireless power transfer system.

[0006] Optionally, before determining the multiple candidate frequency points corresponding to the zero phase angle of the transmitting circuit based on the relationship curves of the transmitting circuit phase angle and the output circuit current as a function of frequency and load in the multi-stage magnetic resonant wireless power transfer system, the method further includes: establishing a circuit model based on the decoupling equivalent circuit corresponding to the multi-stage magnetic resonant wireless power transfer system using electrical laws; determining the expressions for the input current and input impedance of the two-port network corresponding to the multi-stage magnetic resonant wireless power transfer system based on the two-port network correlation laws and the circuit model; and determining that the constant current frequency of the multi-stage magnetic resonant wireless power transfer system is equal to the zero phase angle frequency of the transmitting circuit based on the expressions for the input current and input impedance.

[0007] Optionally, the method further includes: using a circuit model to change the operating frequency of the multi-stage magnetic resonant wireless power transmission system through a frequency sweeping method to obtain the phase angle of the transmitting circuit and the curves showing the relationship between the output circuit current and the frequency and load of the multi-stage magnetic resonant wireless power transmission system.

[0008] Optionally, the method further includes: establishing a time-domain differential model corresponding to the multi-stage magnetic resonant wireless power transfer system; and verifying, based on the time-domain differential model, whether the phase angle of the transmitting circuit current and voltage of the multi-stage magnetic resonant wireless power transfer system is zero at the optimal operating frequency.

[0009] Optionally, when the system is at a candidate frequency point, the output loop current is not affected by the equivalent load of the output loop.

[0010] Optionally, the candidate frequency point with the smallest relative change in output circuit current also has the smallest relative change in transmitter phase.

[0011] According to a second aspect of the present invention, an optimal operating frequency determination device for a multi-stage magnetic resonant wireless power transfer system is also provided. The device includes: a first determination module, configured to determine a plurality of candidate frequency points corresponding to a zero phase angle of the transmitting circuit based on the relationship curves of the phase angle of the transmitting circuit and the output circuit current as a function of frequency and load of the multi-stage magnetic resonant wireless power transfer system; and a selection module, configured to select the candidate frequency point with the smallest relative change in output circuit current within a plurality of frequency ranges corresponding to the plurality of candidate frequency points as the optimal operating frequency of the multi-stage magnetic resonant wireless power transfer system.

[0012] Optionally, the decoupling equivalent circuit of the multi-stage magnetic resonant wireless power transmission system includes: a transmitting circuit, multiple relay coils, and an output circuit connected in sequence; the transmitting circuit, multiple relay coils, and output circuit are all S-type resonant compensation circuits, the transmitting circuit also includes a DC power supply, and the output circuit also includes an equivalent load of a rectifier and a DC resistor.

[0013] Optionally, the device further includes: a first establishment module, used to establish a circuit model based on the decoupling equivalent circuit corresponding to the multi-stage magnetic resonant wireless power transfer system using electrical laws; a second determination module, used to determine the expressions for the input current and input impedance of the two-port network corresponding to the multi-stage magnetic resonant wireless power transfer system based on the relevant laws of two-port networks and the circuit model; and a third determination module, used to determine that the constant current frequency of the multi-stage magnetic resonant wireless power transfer system is equal to the zero phase angle frequency of the transmitting circuit based on the expressions for the input current and input impedance.

[0014] Optionally, the device further includes: a obtaining module, used to obtain the phase angle of the transmitting circuit and the curves of the output circuit current as a function of frequency and load by changing the operating frequency of the multi-stage magnetic resonant wireless power transmission system through a frequency sweeping method using a circuit model.

[0015] Optionally, the device further includes: a second establishment module, used to establish a time-domain differential model corresponding to the multi-stage magnetic resonant wireless power transfer system; and a verification module, used to verify, based on the time-domain differential model, whether the phase angle of the transmitting circuit current and voltage of the multi-stage magnetic resonant wireless power transfer system is zero at the optimal operating frequency.

[0016] Optionally, when the system is at a candidate frequency point, the output loop current is not affected by the equivalent load of the output loop.

[0017] Optionally, the candidate frequency point with the smallest relative change in output circuit current also has the smallest relative change in transmitter phase.

[0018] According to a third aspect of the present invention, an electronic device is also provided, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; wherein the memory is used to store a computer program; and the processor is used to execute the method steps of any of the above embodiments by running the computer program stored in the memory.

[0019] According to a fourth aspect of the present invention, a computer-readable storage medium is also provided, wherein a computer program is stored therein, wherein the computer program is configured to execute the method steps of any of the above embodiments when running.

[0020] In this embodiment of the invention, multiple candidate frequency points corresponding to the zero phase angle of the transmitting circuit are determined based on the relationship curves of the phase angle of the transmitting circuit and the output circuit current as a function of frequency and load in the multi-stage magnetic resonant wireless power transmission system. The candidate frequency point with the smallest relative change in output circuit current within multiple frequency ranges corresponding to these candidate frequency points is selected as the optimal operating frequency of the multi-stage magnetic resonant wireless power transmission system. Multi-stage magnetic resonant wireless power transmission systems, i.e., wireless power transmission devices, are prone to frequency drift due to factors such as ambient temperature and mechanical system aging, which makes it impossible to guarantee constant current output. This invention determines multiple candidate frequency points through simulation curves and selects the candidate frequency point with the least impact on output current as the optimal operating frequency. This achieves the effects of maintaining stable system output, reducing system reactive power, and improving system efficiency, thus solving the problem in related technologies where wireless power transmission devices cannot guarantee constant current output due to frequency fluctuations.

[0021] In this embodiment of the invention, a time-domain differential model corresponding to the multi-stage magnetic resonance wireless power transmission system is established. Based on the time-domain differential model, it is verified whether the phase angle of the current and voltage of the transmission circuit is zero at the optimal operating frequency. This proves that adjusting the system using the optimal operating frequency after the system frequency shift can achieve the effect of restoring the system to the resonance state, thus realizing the verification of the effectiveness of the optimal operating frequency. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the hardware environment for an optional method for determining the optimal operating frequency of a multi-stage magnetic resonant wireless power transmission system according to an embodiment of the present invention. Figure 2 This is a flowchart illustrating an optional method for determining the optimal operating frequency of a multi-stage magnetic resonant wireless power transmission system according to an embodiment of the present invention. Figure 3 This is a circuit diagram of a multi-stage magnetic resonance wireless power transmission system according to an embodiment of the present invention; Figure 4a This is a curve showing the relationship between the phase angle of the transmitting circuit of a multi-stage magnetic resonant wireless power transmission system according to an embodiment of the present invention and the frequency and load. Figure 4bThis is a curve showing the relationship between the output circuit current of a multi-stage magnetic resonant wireless power transmission system according to an embodiment of the present invention and the frequency and load. Figure 5a This is a phase and frequency relationship diagram near a frequency of 195.8 kHz according to an embodiment of the present invention; Figure 5b This is a graph showing the relationship between the output circuit current and frequency near a frequency of 195.8 kHz according to an embodiment of the present invention; Figure 6a This is a phase and frequency relationship diagram near a frequency of 210.7 kHz according to an embodiment of the present invention; Figure 6b This is a graph showing the relationship between the output circuit current and frequency near a frequency of 210.7 kHz according to an embodiment of the present invention; Figure 7a This is a schematic diagram of the time-domain differential model corresponding to the multi-stage magnetic resonance wireless power transfer system according to an embodiment of the present invention; Figure 7b This is a simulation waveform diagram of the input voltage and input current of a multi-stage magnetic resonance wireless power transmission system according to an embodiment of the present invention when the transmitting side is not resonant; Figure 7c This is a simulation waveform diagram of the input voltage and input current when the transmitting side of the multi-stage magnetic resonance wireless power transmission system resonates according to an embodiment of the present invention. Figure 8 This is a structural block diagram of an optional multi-stage magnetic resonant wireless power transmission system optimal operating frequency determination device according to an embodiment of the present invention. Figure 9 This is a schematic diagram of the decoupling equivalent circuit of a multi-stage magnetic resonant wireless power transmission system according to an embodiment of the present invention. Figure 10 This is a structural block diagram of an optional electronic device according to an embodiment of the present invention. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0026] It should be noted that in the description of this invention, the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices. The terms "installed," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; a connection within two elements; a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] According to one aspect of the present invention, a method for determining the optimal operating frequency of a multi-stage magnetic resonant wireless power transfer system is provided. Optionally, in this embodiment, the above-described method for determining the optimal operating frequency of a multi-stage magnetic resonant wireless power transfer system can be applied to, for example... Figure 1 In the hardware environment shown. For example... Figure 1 As shown, terminal 102 may include memory 104, processor 106, and display 108 (optional component). Terminal 102 can communicate with server 112 via network 110. Server 112 can provide services (such as application services) to the terminal or clients installed on the terminal. Database 114 can be set up on or independently of server 112 to provide data storage services to server 112. In addition, server 112 may run a processing engine 116, which can be used to execute the steps performed by server 112.

[0028] Optionally, terminal 102 may be, but is not limited to, a terminal capable of computing data, such as a mobile terminal (e.g., a mobile phone, tablet computer), a laptop computer, a PC (Personal Computer), etc. The aforementioned network may include, but is not limited to, a wireless network or a wired network. The wireless network includes Bluetooth, Wi-Fi (Wireless Fidelity), and other networks that enable wireless communication. The aforementioned wired network may include, but is not limited to, a wide area network (WAN), a metropolitan area network (MAN), and a local area network (LAN). The aforementioned server 112 may include, but is not limited to, any hardware device capable of computing.

[0029] Furthermore, in this embodiment, the method for determining the optimal operating frequency of the multi-stage magnetic resonant wireless power transmission system can also be applied, but is not limited to, to a powerful independent processing device without data interaction. For example, this processing device can be, but is not limited to, a powerful terminal device; that is, the various operations in the method for determining the optimal operating frequency of the multi-stage magnetic resonant wireless power transmission system can be integrated into a single independent processing device. The above is merely an example, and no limitation is made in this embodiment.

[0030] Optionally, in this embodiment, the optimal operating frequency determination method for the multi-stage magnetic resonant wireless power transfer system can be executed by the server 112, by the terminal 102, or by both the server 112 and the terminal 102. Alternatively, the terminal 102 can execute the optimal operating frequency determination method for the multi-stage magnetic resonant wireless power transfer system according to this embodiment of the invention, which can also be executed by a client installed on it.

[0031] Taking the method for determining the optimal operating frequency of a multi-stage magnetic resonant wireless power transfer system as an example applied to the central processing unit, Figure 2 This is a flowchart illustrating an optional method for determining the optimal operating frequency of a multi-stage magnetic resonant wireless power transfer system according to an embodiment of the present invention. Figure 2 As shown, the process of this method may include the following steps: Step S201: Based on the phase angle of the transmitting circuit and the curves showing the relationship between the output circuit current and frequency and load in the multi-stage magnetic resonant wireless power transfer system, determine multiple candidate frequency points corresponding to the zero phase angle of the transmitting circuit. Optionally, Figure 3 This is a circuit diagram of a multi-stage magnetic resonant wireless power transfer system according to an embodiment of the present invention. The multi-stage magnetic resonant wireless power transfer system is hereinafter referred to as the system. From left to right, the circuit diagram shows the system's transmitting circuit, multiple relay coils, and receiving circuit. The transmitting circuit includes a DC power supply. V dc DC power supply V dc The system inverter stage converts voltage to AC. S 1 -S 4. Resonant capacitor C 1. Resonant inductor L 1 and the internal resistance of the resonant inductor R 1; Each repeater coil includes a resonant capacitor, a resonant inductor, and the internal resistance of the resonant inductor; the receiving circuit includes a resonant capacitor. C n Resonant inductor L n Resonant inductor internal resistance R nThe rectifier stage that converts alternating current (AC) to direct current (DC) D 1 -D 4. Filter capacitor C f and equivalent load R It should be noted that, M 12 -M (n-1)n The mutual inductance between the coils and the coupling between them are considered. Given specific values ​​for parameters such as the number of coils, resonant inductance, resonant capacitance, inductor resistance, and equivalent load of the output circuit in a multi-stage magnetic resonant wireless power transfer system, we can obtain... Figure 4a as well as Figure 4b The curves showing the relationship between the phase angle of the transmitting circuit and frequency and load, and the curves showing the relationship between the output circuit current and frequency and load of the multi-stage magnetic resonant wireless power transmission system. Figure 4a and Figure 4b The curves showing the relationship between the phase angle of the transmitting circuit and the output circuit current as a function of frequency and load constitute a multi-stage magnetic resonant wireless power transfer system. Based on these curves, multiple frequency points corresponding to a zero phase angle of the transmitting circuit are identified as candidate frequencies for the system's optimal operating frequency. These candidate frequencies are the resonant frequencies at which each coil of the system resonates. Figure 4a As shown, there are two candidate frequency points, f1=195.8kHz and f2=210.7kHz.

[0032] Step S202: Select the candidate frequency point with the smallest relative change in output circuit current within multiple frequency ranges corresponding to multiple candidate frequency points as the optimal operating frequency of the multi-stage magnetic resonant wireless power transfer system. Optionally, when the system's operating frequency changes near candidate frequency points f1 or f2, the phase angle of the transmitting circuit and the output circuit current will also change accordingly. Specifically, Figure 5a as well as Figure 5b When the system operating frequency varies around f1 = 195.8 kHz, the phase angle of the transmit circuit is... Figure 5a The mid-phase and output circuit current are Figure 5b The variation of I5 is shown. It should be noted that this embodiment uses a system with five coils (one transmitting circuit, three relay coils, and one receiving circuit) as an example; therefore, I5 corresponds to the output circuit current. Similarly, Figure 6a as well as Figure 6b The changes in the phase angle of the transmitting circuit and the current of the output circuit are shown in Table 1 when the system operating frequency varies around f2 = 210.7 kHz. Table 1 shows the changes in the phase angle of the transmitting circuit and the current of the output circuit. From this table, the candidate frequency point with the smallest relative change in the output circuit current, i.e., f2 = 210.7 kHz, is selected as the optimal operating frequency for the multi-stage magnetic resonant wireless power transfer system.

[0033] Table 1. Transmitter circuit phase angle and output circuit current variation.

[0034] In this embodiment of the invention, multiple candidate frequency points corresponding to the zero phase angle of the transmitting circuit are determined based on the relationship curves of the phase angle of the transmitting circuit and the output circuit current as a function of frequency and load in the multi-stage magnetic resonant wireless power transmission system. The candidate frequency point with the smallest relative change in output circuit current within multiple frequency ranges corresponding to these candidate frequency points is selected as the optimal operating frequency of the multi-stage magnetic resonant wireless power transmission system. Multi-stage magnetic resonant wireless power transmission systems, i.e., wireless power transmission devices, are prone to frequency drift due to factors such as ambient temperature and mechanical system aging, which makes it impossible to guarantee constant current output. This invention determines multiple candidate frequency points through simulation curves and selects the candidate frequency point with the least impact on output current as the optimal operating frequency. This achieves the effects of maintaining stable system output, reducing system reactive power, and improving system efficiency, thus solving the problem in related technologies where wireless power transmission devices cannot guarantee constant current output due to frequency fluctuations.

[0035] As an optional embodiment, the candidate frequency point with the smallest relative change in output circuit current also exhibits the smallest relative change in transmitter circuit phase. Optionally, f2 = 210.7 kHz in Table 1 is the candidate frequency point with the smallest relative change in output circuit current. At this point, the transmitter circuit phase angle change is [-12.5°, 4.8°], and the relative change in transmitter circuit phase angle is 138.4%, which is the smallest relative change in transmitter circuit phase angle among all candidate frequency points, consistent with the smallest relative change in output circuit current. In this embodiment of the invention, the optimal operating frequency of the system is obtained by selecting a suitable frequency to make the system least sensitive to changes in frequency parameters.

[0036] As an optional embodiment, before determining multiple candidate frequency points corresponding to the zero phase angle of the transmitting circuit based on the relationship curves of the transmitting circuit phase angle and the output circuit current as a function of frequency and load in the multi-stage magnetic resonant wireless power transfer system, the method further includes: establishing a circuit model based on the decoupling equivalent circuit corresponding to the multi-stage magnetic resonant wireless power transfer system using electrical laws; determining the expressions for the input current and input impedance of the two-port network corresponding to the multi-stage magnetic resonant wireless power transfer system based on the circuit model according to the relevant laws of two-port networks; and determining that the constant current frequency of the multi-stage magnetic resonant wireless power transfer system is equal to the zero phase angle frequency of the transmitting circuit based on the expressions for the input current and input impedance.

[0037] Optionally, before establishing the circuit model, Figure 3The circuit of the multi-stage magnetic resonant wireless power transfer system shown is decoupled and equivalent, meaning that only switching elements are considered at the power supply and load ends, and only electromagnetic coupling elements are considered for the intermediate coil. Then, based on Kirchhoff's voltage law and current law, a circuit model is established for the decoupled equivalent circuit of the multi-stage magnetic resonant wireless power transfer system, i.e., a system of equations is written:

[0038] In the formula, , C 1 -C n Here are the resonant capacitances of each coil. L 1 -L n For the resonant inductance of each coil, R 1 -R n Let be the internal resistance of the resonant inductance of each coil. M 12 -M (n-1)n For the mutual inductance between the coils, Let be the current vector of each coil. Let be the voltage vector of each coil.

[0039] For ease of analysis, all coils in the system use the same dimensions, meaning that the resonant capacitance and resonant inductance of each coil are equal.

[0040]

[0041] At the same time, the coils are evenly distributed, that is:

[0042] At this point, the above circuit model can be simplified to:

[0043] In the formula, Representing the i The coil and the first j The coupling coefficients between the coils are further simplified by deleting the first and last rows of the matrix to form a new matrix, since the simplified matrix (circuit model) is a real symmetric matrix.

[0044] The above matrix is ​​divided into three sub-matrices according to the parameter properties: transmitting circuit, relay coil, and output circuit.

[0045] In the formula, They represent:

[0046] The relevant laws of two-port networks are applied to the above circuit model. A two-port network is a circuit or device with two ports, which are connected to the internal network of the circuit. A port consists of two terminals. When these two terminals satisfy the port condition—that is, the current flowing into one terminal equals the current flowing out of the other terminal—these two terminals constitute a port. In other words, the same current flows into and out of the same port; that is, the input current at the port equals the output current. Two-port networks can represent the entire circuit or a part of it using their corresponding external characteristic parameters, without considering its internal details. The represented circuit thus becomes a "black box" with a set of special properties, thereby simplifying analysis and abstracting the physical composition of the circuit. The input current of the two-port network corresponding to the above circuit model is... and input impedance The expression is:

[0047]

[0048] The impedances are as follows:

[0049] For systems with defined parameters, such as when At this time, the system output current and input impedance can be expressed as follows:

[0050]

[0051] At this time, the output current is only related to the input voltage. and impedance Z 12 Related to input impedance Only with load With impedance Z 12 Therefore, when the system parameters are given, the input impedance is a fixed value. At this time, the system output constant current characteristic and the zero-phase angle characteristic of the transmitting circuit appear simultaneously, meaning that the zero-phase angle frequency point of the transmitting circuit is the same as the constant current frequency point. In this embodiment of the invention, through circuit model derivation and analysis, it was concluded that the constant current frequency of the multi-stage magnetic resonant wireless power transfer system is equal to the zero-phase angle frequency of the transmitting circuit when the system parameters are given. This lays a theoretical foundation for subsequently determining candidate frequency points based on the phase angle of the transmitting circuit and verifying the optimal operating frequency.

[0052] As an optional embodiment, the method further includes: using a circuit model to change the operating frequency of the multi-stage magnetic resonant wireless power transfer system via a frequency sweep method to obtain the curves showing the relationship between the phase angle of the transmitting circuit and the current of the output circuit as a function of frequency and load. Optionally, by establishing a circuit model corresponding to the multi-stage magnetic resonant wireless power transfer system, the operating frequency is changed by using a frequency sweep step to change the corresponding system parameters, thereby obtaining the curves showing the relationship between the phase angle of the transmitting circuit and the current of the output circuit as a function of frequency and load. Specifically, these curves include, for example,... Figure 4a The curves showing the relationship between the phase angle of the transmitting circuit and frequency and load are as follows: Figure 4b The curves shown represent the relationship between the output circuit current and the frequency and load.

[0053] As an optional embodiment, the method further includes: establishing a time-domain differential model corresponding to the multi-stage magnetic resonant wireless power transfer system; and verifying, based on the time-domain differential model, whether the phase angles of the transmitting circuit current and voltage of the multi-stage magnetic resonant wireless power transfer system are zero at the optimal operating frequency. Optionally, Figure 7a This is a schematic diagram of a time-domain differential model of a multi-stage magnetic resonant wireless power transfer system, consisting of one transmitting circuit, three relay coils, and one output circuit. S1, S2, S3, and S4 are the pulse signals controlling the inverter's operation. By changing the parameters in the time-domain differential model in simulation software, simulation results of the system's input voltage U1 and input current I1 at a system frequency of 200kHz are obtained. Figure 7b As shown, at this time, the transmitting side, i.e., the transmitting circuit, is in a non-resonant state and the current phase differs from the voltage phase. . Figure 7c The simulation results show the input voltage and input current of the system after adjusting the operating frequency to the optimal operating frequency. At this point, the transmitter side is in a resonant state and the current phase differs from the voltage phase. In this embodiment of the invention, a time-domain differential model was established using simulation software to experimentally verify the optimal operating frequency of the system, thereby improving the reliability of the conclusions.

[0054] As an optional embodiment, when the system is at a candidate frequency point, the system output loop current is not affected by the equivalent load of the output loop. Optionally, Figure 4b The figure shows the relationship between the system's output loop current and frequency and load. Different curves in the figure correspond to the relationship between the output loop current and frequency under different equivalent loads RL of the output loop. Multiple curves intersect at f1 and f2, which means that no matter what the value of the load RL is, the system output loop current is the same. Therefore, when the system is at the candidate frequency point, the system output loop current is not affected by the equivalent load of the output loop.

[0055] According to another aspect of the present invention, an optimal operating frequency determination device for a multi-stage magnetic resonant wireless power transmission system is also provided. Figure 8 This is a structural block diagram of an optional multi-stage magnetic resonant wireless power transfer system optimal operating frequency determination device according to an embodiment of the present invention, such as... Figure 8 As shown, the device may include: a first determining module 801, used to determine multiple candidate frequency points corresponding to the zero phase angle of the transmitting circuit based on the phase angle of the transmitting circuit and the curve of the output circuit current changing with frequency and load of the multi-stage magnetic resonant wireless power transmission system; and a selecting module 802, used to select the candidate frequency point with the smallest relative change of output circuit current in multiple frequency ranges corresponding to the multiple candidate frequency points as the optimal operating frequency of the multi-stage magnetic resonant wireless power transmission system.

[0056] It should be noted that the first determining module 801 in this embodiment can be used to execute the above step S201, and the selecting module 802 can be used to execute the above step S202.

[0057] By using the above modules, multiple candidate frequency points are determined, and the candidate frequency point with the least impact on the output current is selected as the optimal operating frequency. This achieves the effect of maintaining stable system output, reducing system reactive power, and improving system efficiency, thus solving the problem in related technologies where wireless power transmission devices cannot guarantee constant current output due to frequency fluctuations.

[0058] As an optional embodiment, the decoupling equivalent circuit of the multi-stage magnetic resonant wireless power transfer system includes: a transmitting circuit, multiple repeater coils, and an output circuit connected in sequence; the transmitting circuit, multiple repeater coils, and output circuit are all S-type resonant compensation circuits, the transmitting circuit also includes a DC power supply, and the output circuit also includes an equivalent load of a rectifier and a DC resistor. Optionally, Figure 9 yes Figure 3 The decoupling equivalent circuit diagram of a multi-stage magnetic resonant wireless power transfer system, where only switching elements are considered at the power supply and load ends, and only electromagnetic coupling elements are considered for the intermediate coil. M 12 -M (n-1)n From left to right, the components are the transmitting circuit, multiple relay coils, and the output circuit. The transmitting circuit includes a DC power supply with a voltage of [voltage value missing]. u 1. The output circuit includes the rectifier and the equivalent load R of the DC resistor. L The transmitting circuit, multiple relay coils, and output circuit are all S-type resonant compensation circuits, i.e., composed of inductors. L i ,resistance R i and capacitor C iA series resonant compensation circuit. In this embodiment of the invention, by appropriately adding a resonant coil as a repeater between the transmitting and receiving circuits, the transmission distance can be extended while ensuring system efficiency or power. It should be noted that the repeaters are all composed of resonant capacitors and resonant inductors to ensure that the system operates at the resonant frequency (…). Only when the system operates at its resonant frequency can the condition for adding a relay coil to enhance the magnetic field strength of the transmission channel be met. The energy transfer efficiency between coils is highest when the system is operating at its resonant frequency.

[0059] As an optional embodiment, the device further includes: a first establishment module, used to establish a circuit model based on the decoupling equivalent circuit corresponding to the multi-stage magnetic resonant wireless power transfer system using electrical laws; a second determination module, used to determine the expressions for the input current and input impedance of the two-port network corresponding to the multi-stage magnetic resonant wireless power transfer system based on the relevant laws of two-port networks and the circuit model; and a third determination module, used to determine that the constant current frequency of the multi-stage magnetic resonant wireless power transfer system is equal to the zero phase angle frequency of the transmitting circuit based on the expressions for the input current and input impedance.

[0060] As an optional embodiment, the device further includes: a obtaining module, used to obtain the phase angle of the transmitting circuit and the curves of the output circuit current as a function of frequency and load of the multi-stage magnetic resonant wireless power transmission system by changing the operating frequency of the multi-stage magnetic resonant wireless power transmission system through a frequency sweeping method using a circuit model.

[0061] As an optional embodiment, the device further includes: a second establishment module for establishing a time-domain differential model corresponding to the multi-stage magnetic resonant wireless power transfer system; and a verification module for verifying, based on the time-domain differential model, whether the phase angle of the transmitting circuit current and voltage of the multi-stage magnetic resonant wireless power transfer system is zero at the optimal operating frequency.

[0062] As an optional embodiment, when the system is at a candidate frequency point, the system output loop current is not affected by the equivalent load of the output loop.

[0063] As an alternative embodiment, the candidate frequency point with the smallest relative change in output circuit current also has the smallest relative change in transmitter phase.

[0064] It should be noted that the examples and application scenarios implemented by the above modules and corresponding steps are the same, but are not limited to the content disclosed in the above embodiments. It should also be noted that the above modules, as part of a device, can operate in environments such as... Figure 1 The hardware environment shown can be implemented through software or hardware, and the hardware environment includes the network environment.

[0065] According to another aspect of the present invention, an electronic device for implementing the above-described method for determining the optimal operating frequency of a multi-stage magnetic resonant wireless power transmission system is also provided. The electronic device may be a server, a terminal, or a combination thereof.

[0066] Figure 10 This is a structural block diagram of an optional electronic device according to an embodiment of the present invention, such as... Figure 10 As shown, the system includes a processor 1001, a communication interface 1002, a memory 1003, and a communication bus 1004. The processor 1001, communication interface 1002, and memory 1003 communicate with each other via the communication bus 1004. The memory 1003 stores computer programs. When the processor 1001 executes the computer program stored in the memory 1003, it performs the following steps: Based on the relationship curves of the phase angle of the transmitting circuit and the output circuit current with frequency and load of the multi-stage magnetic resonant wireless power transfer system, multiple candidate frequency points corresponding to the zero phase angle of the transmitting circuit are determined; the candidate frequency point with the smallest relative change of the output circuit current in multiple frequency ranges corresponding to the multiple candidate frequency points is selected as the optimal operating frequency of the multi-stage magnetic resonant wireless power transfer system.

[0067] Optionally, in this embodiment, the communication bus can be a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. This communication bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 10 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0068] The communication interface is used for communication between the aforementioned electronic devices and other devices.

[0069] The memory may include RAM, or non-volatile memory, such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0070] As an example, such as Figure 10 As shown, the memory 1003 may include, but is not limited to, the first determining module 801 and the selecting module 802 in the optimal operating frequency determining device of the multi-stage magnetic resonant wireless power transfer system. Furthermore, it may include, but is not limited to, other module units in the optimal operating frequency determining device of the multi-stage magnetic resonant wireless power transfer system, which will not be described in detail in this example.

[0071] The processor mentioned above can be a general-purpose processor, including but not limited to: CPU (Central Processing Unit), NP (Network Processor), etc.; it can also be DSP (Digital Signal Processor), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0072] In addition, the aforementioned electronic device also includes a display for showing the determination result of the optimal operating frequency of the multi-stage magnetic resonant wireless power transfer system.

[0073] Optionally, specific examples in this embodiment can refer to the examples described in the above embodiments, and will not be repeated here.

[0074] Those skilled in the art will understand that Figure 10 The structure shown is for illustrative purposes only. The device that implements the above-described method for determining the optimal operating frequency of the multi-stage magnetic resonant wireless power transmission system can be a terminal device, such as a smartphone (e.g., an Android phone, an iOS phone), a tablet computer, a PDA, a mobile Internet device (MID), a PAD, or other terminal devices. Figure 10 This does not limit the structure of the aforementioned electronic devices. For example, the terminal device may also include components that are more... Figure 10 The more or fewer components shown (such as network interfaces, display devices, etc.), or having the same Figure 10 The different configurations shown.

[0075] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing the hardware related to the terminal device. The program can be stored in a computer-readable storage medium, which may include: flash drive, ROM, RAM, disk or optical disk, etc.

[0076] According to another aspect of the present invention, a storage medium is also provided. Optionally, in this embodiment, the storage medium can be used to execute program code for a method for determining the optimal operating frequency of a multi-stage magnetic resonant wireless power transfer system.

[0077] Optionally, in this embodiment, the storage medium may be located on at least one of the network devices in the network shown in the above embodiment.

[0078] Optionally, in this embodiment, the storage medium is configured to store program code for performing the following steps: Based on the relationship curves of the phase angle of the transmitting circuit and the output circuit current with frequency and load of the multi-stage magnetic resonant wireless power transfer system, multiple candidate frequency points corresponding to the zero phase angle of the transmitting circuit are determined; the candidate frequency point with the smallest relative change of the output circuit current in multiple frequency ranges corresponding to the multiple candidate frequency points is selected as the optimal operating frequency of the multi-stage magnetic resonant wireless power transfer system.

[0079] Optionally, specific examples in this embodiment can refer to the examples described in the above embodiments, and will not be repeated in this embodiment.

[0080] Optionally, in this embodiment, the storage medium may include, but is not limited to, various media capable of storing program code, such as USB flash drives, ROMs, RAMs, portable hard drives, magnetic disks, or optical disks.

[0081] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. In the above embodiments of the present invention, the descriptions of each embodiment have their own emphasis, and for parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0082] In the several embodiments provided by this invention, it should be understood that the disclosed client can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection of units or modules may be electrical or other forms.

[0083] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the solution provided in this embodiment, depending on actual needs.

[0084] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0085] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for determining the optimal operating frequency of a multi-stage magnetic resonant wireless power transfer system, characterized in that, The method includes: A circuit model is established based on the decoupling equivalent circuit corresponding to the multi-stage magnetic resonant wireless power transfer system using electrical laws. Based on the relevant laws of two-port networks, the expressions for the input current and input impedance of the two-port network corresponding to the multi-stage magnetic resonant wireless power transfer system are determined according to the circuit model. Based on the expressions for the input current and input impedance, the constant current frequency of the multi-stage magnetic resonant wireless power transfer system is determined to be equal to the zero phase angle frequency of the transmitting circuit. By using a circuit model and frequency sweeping method to change the operating frequency of a multi-stage magnetic resonant wireless power transmission system, the relationship curves of the phase angle of the transmitting circuit and the load, as well as the relationship curves of the output circuit current and the frequency and load, are obtained. Based on the curve showing the relationship between the phase angle of the transmitting circuit of the multi-stage magnetic resonant wireless power transmission system and the frequency and load, multiple candidate frequency points corresponding to the zero phase angle of the transmitting circuit are determined. The candidate frequency point with the smallest relative change in output circuit current within multiple frequency ranges corresponding to the multiple candidate frequency points is selected as the optimal operating frequency of the multi-stage magnetic resonant wireless power transmission system.

2. The method for determining the optimal operating frequency of the multi-stage magnetic resonant wireless power transfer system according to claim 1, characterized in that, The method further includes: Establish a time-domain differential model for a multi-stage magnetic resonant wireless power transfer system; The time-domain differential model is used to verify whether the phase angle of the transmitting circuit current and voltage of the multi-stage magnetic resonant wireless power transmission system is zero at the optimal operating frequency.

3. The method for determining the optimal operating frequency of the multi-stage magnetic resonant wireless power transfer system according to claim 1, characterized in that, When the system is at a candidate frequency point, the output loop current is not affected by the equivalent load of the output loop.

4. The method for determining the optimal operating frequency of the multi-stage magnetic resonant wireless power transfer system according to claim 1, characterized in that, The phase angle of the transmitting circuit at the candidate frequency point with the smallest relative change in output circuit current is also the smallest.

5. A device for determining the optimal operating frequency of a multi-stage magnetic resonant wireless power transfer system, characterized in that, The device includes: The first module establishes a circuit model based on the decoupling equivalent circuit of the multi-stage magnetic resonant wireless power transfer system using electrical laws. The second module determines the expressions for the input current and input impedance of the two-port network corresponding to the multi-stage magnetic resonant wireless power transfer system based on the relevant laws of two-port networks and the circuit model. The third module determines the constant current frequency of the multi-stage magnetic resonant wireless power transfer system based on the expressions for the input current and input impedance, ensuring that the constant current frequency is equal to the zero phase angle frequency of the transmitting circuit. The module is used to obtain the phase angle of the transmitting circuit and the curves of the output circuit current as a function of frequency and load by changing the operating frequency of the multi-stage magnetic resonant wireless power transmission system through the frequency sweeping method using the circuit model. The first determining module is used to determine multiple candidate frequency points corresponding to the zero phase angle of the transmission circuit based on the relationship curve of the phase angle of the transmission circuit of the multi-stage magnetic resonant wireless power transmission system with frequency and load. The selection module is used to select the candidate frequency point with the smallest relative change in output circuit current within multiple frequency ranges corresponding to the multiple candidate frequency points as the optimal operating frequency of the multi-stage magnetic resonant wireless power transmission system.

6. The optimal operating frequency determination device for the multi-stage magnetic resonant wireless power transfer system according to claim 5, characterized in that, The decoupling equivalent circuit of the multi-stage magnetic resonant wireless power transmission system includes: a transmitting circuit, multiple relay coils, and an output circuit connected in sequence. The transmitting circuit, multiple relay coils, and output circuit are all S-type resonant compensation circuits. The transmitting circuit also includes a DC power supply, and the output circuit also includes a rectifier and an equivalent load of a DC resistor.

7. 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 to store computer programs; The processor is configured to perform the method steps of any one of claims 1 to 4 by running the computer program stored in the memory.

8. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, wherein the computer program, when executed by a processor, implements the steps of the method described in any one of claims 1 to 4.

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