Wireless power transmission system magnetic field analysis method, device, equipment and storage medium

Abstract

The present invention discloses a method, device, equipment, and storage medium for analyzing the magnetic field of a wireless power transmission system. The method includes: calculating the composite magnetic field of the transmitting coil and the equivalent surface current based on the excitation magnetic field of the transmitting coil and the equivalent surface current; calculating the initial current value of the receiving coil based on the composite magnetic field; calculating the secondary current value of the receiving coil based on the composite magnetic field of the transmitting coil, the equivalent surface current, and the receiving coil; calculating the secondary current value of the receiving coil multiple times until the relative difference in current density corresponding to the current secondary value of the receiving coil calculated this time and the previous time meets a preset value, and determining that the magnetic field calculated based on the initial current value of the receiving coil, the current of the transmitting coil, and the equivalent surface current is the composite magnetic field of the transmitting coil, the equivalent surface current, and the receiving coil. The above technical solution realizes the analysis of the magnetic field distribution of wireless power transmission systems with different coil structures.

Description

Technical Field

[0001] The present invention relates to the field of wireless power transmission technology, and in particular to a method, device, equipment and storage medium for analyzing the magnetic field of a wireless power transmission system. Background Art

[0002] The development of wireless power transmission technology offers a new solution for powering data acquisition devices and power inspection robots in fully digital power distribution systems—namely, wireless power transmission for contactless charging from the power source to the load. Mainstream wireless power transmission technologies include electromagnetic induction, magnetic coupling resonant, and microwave.

[0003] Because electromagnetic induction wireless power transmission relies primarily on induced voltage or induced charge between coils or plates to transmit power, this type of technology has a short power transmission distance. Considering the insulation requirements and power supply flexibility of the power distribution system, inductive wireless power transmission is not suitable for powering equipment such as power inspection robots. Microwave wireless power transmission technology requires the installation of specific transmitting and receiving antennas for power transmission in a fixed direction and route, and also does not meet the power supply requirements of the power distribution system. Magnetic coupling resonant wireless power transmission relies on the resonance between the transmitting and receiving coils to achieve medium- and long-distance wireless power transmission. Compared with the other two types of wireless power transmission, magnetic coupling resonant wireless power transmission best meets the requirements.

[0004] Maxwell's equations describe the spatial distribution of electromagnetic fields and their temporal variations. These equations serve as the theoretical foundation for in-depth research on the magnetic field of coils. Due to the computational complexity of Maxwell's equations, analyzing and studying different coil structures from the most fundamental theoretical perspective is time-consuming and labor-intensive, hindering the design and improvement of wireless power transmission systems tailored to specific requirements. Therefore, a method for analyzing the magnetic field distribution characteristics of different coil structures in wireless power transmission systems is considered. This provides a universal research method for coils of varying structures, facilitating the rapid design of wireless power transmission systems that meet specific requirements. Summary of the Invention

[0005] The present invention provides a method, device, equipment and storage medium for analyzing the magnetic field of a wireless power transmission system, so as to analyze the magnetic field distribution of wireless power transmission systems with different coil structures.

[0006] According to one aspect of the present invention, a method for analyzing a magnetic field in a wireless power transmission system is provided. The wireless power transmission system includes a transmitting coil, a ferromagnetic material, and a receiving coil. The method for analyzing a magnetic field in a wireless power transmission system includes:

[0007] Calculate the exciting magnetic field of the transmitting end coil according to the current of the transmitting end coil;

[0008] Using the preset hysteresis model, the surface current is equivalent to the ferromagnetic material, and the excitation magnetic field of the equivalent surface current is calculated;

[0009] Calculating a synthetic magnetic field of the transmitting end coil and the equivalent surface current based on the exciting magnetic field of the transmitting end coil and the exciting magnetic field of the equivalent surface current;

[0010] Calculating an initial current value of the receiving-end coil according to a synthetic magnetic field of the transmitting-end coil and the equivalent surface current;

[0011] Calculating a composite magnetic field of the transmitting-end coil, the equivalent surface current, and the receiving-end coil according to an initial current value of the receiving-end coil, the current of the transmitting-end coil, and the equivalent surface current;

[0012] Calculating a secondary value of the current of the receiving-end coil according to the synthetic magnetic field of the transmitting-end coil, the equivalent surface current, and the receiving-end coil;

[0013] The secondary value of the current of the receiving-end coil is calculated multiple times until a relative difference in current density corresponding to the current secondary value of the receiving-end coil calculated this time and the previous calculated current secondary value meets a preset value, and a magnetic field calculated based on the initial current value of the receiving-end coil, the current of the transmitting-end coil, and the equivalent surface current is determined to be a composite magnetic field of the transmitting-end coil, the equivalent surface current, and the receiving-end coil.

[0014] Optionally, the current of the transmitting end coil is simplified to a line current;

[0015] And / or, the current of the receiving-end coil is simplified to the line current.

[0016] Optionally, before calculating the excitation magnetic field of the transmitting-end coil according to the current of the transmitting-end coil, the method further includes:

[0017] After the power is turned on, a resonant system is formed between the transmitting end coil and the receiving end coil;

[0018] After the power is turned on, the ferromagnetic material is completely magnetized in the resonant system.

[0019] Optionally, when the relative difference in current density corresponding to the current secondary value of the receiving end coil calculated this time and last time meets a preset value, the relative difference in current density corresponding to the current secondary value of the receiving end coil calculated this time and last time is not greater than 0.1%.

[0020] Optionally, calculating the excitation magnetic field of the transmitting-end coil according to the current of the transmitting-end coil includes:

[0021] Determining the line current density of the transmitting end coil according to the body current of the transmitting end coil and the number of turns of the transmitting end coil; wherein the body current of the transmitting end coil is simplified to the line current;

[0022] The intensity of the magnetic field excited by the transmitting end line segment in the surrounding space is determined according to the linear current density of the transmitting end coil.

[0023] Optionally, after determining the intensity of the magnetic field excited by the transmitting end line segment in the surrounding space according to the linear current density of the transmitting end coil, the method further includes:

[0024] The intensity of the magnetic field excited by the transmitting end line segment in the surrounding space and varying with time is determined according to the intensity of the magnetic field excited by the transmitting end line segment in the surrounding space.

[0025] Optionally, using a preset hysteresis model, the surface current is equivalent to replacing the ferromagnetic material, and the excitation magnetic field of the equivalent surface current is calculated including:

[0026] The Jiles-Atherton (JA) hysteresis model is used to replace the ferromagnetic material with the surface current, and the exciting magnetic field of the equivalent surface current is calculated.

[0027] According to another aspect of the present invention, there is provided a device for analyzing a magnetic field in a wireless power transmission system, comprising:

[0028] The transmitting end coil magnetic field calculation module is used to calculate the exciting magnetic field of the transmitting end coil according to the current of the transmitting end coil;

[0029] The equivalent surface current magnetic field calculation module is used to use the preset hysteresis model to replace the ferromagnetic material with the surface current and calculate the excitation magnetic field of the equivalent surface current;

[0030] a module for calculating a synthetic magnetic field of a transmitting end coil and an equivalent surface current, configured to calculate a synthetic magnetic field of the transmitting end coil and the equivalent surface current based on the excitation magnetic field of the transmitting end coil and the excitation magnetic field of the equivalent surface current;

[0031] A receiving-end coil current initial value calculation module, configured to calculate the receiving-end coil current initial value based on the synthetic magnetic field of the transmitting-end coil and the equivalent surface current;

[0032] a total synthetic magnetic field calculation module, configured to calculate the synthetic magnetic field of the transmitting-end coil, the equivalent surface current, and the receiving-end coil based on the initial current value of the receiving-end coil, the current of the transmitting-end coil, and the equivalent surface current;

[0033] a receiving-end coil current secondary value calculation module, which calculates the receiving-end coil current secondary value according to the transmitting-end coil, the equivalent surface current and the synthetic magnetic field of the receiving-end coil;

[0034] The synthetic magnetic field confirmation module is used to calculate the secondary value of the current of the receiving end coil multiple times until the relative difference in current density corresponding to the current secondary value of the receiving end coil calculated this time and the previous calculated current secondary value meets a preset value, and determine that the magnetic field calculated based on the initial current value of the receiving end coil, the current of the transmitting end coil and the equivalent surface current is the synthetic magnetic field of the transmitting end coil, the equivalent surface current and the receiving end coil.

[0035] According to another aspect of the present invention, there is provided an electronic device, comprising:

[0036] at least one processor; and

[0037] a memory communicatively connected to the at least one processor; wherein,

[0038] The memory stores a computer program that can be executed by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can perform the wireless power transmission system magnetic field analysis method described in any embodiment of the present invention.

[0039] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the wireless power transmission system magnetic field analysis method described in any embodiment of the present invention when executed.

[0040] The magnetic field analysis method, device, equipment and storage medium of the wireless power transmission system of the embodiment of the present invention considers the skin effect of the coil current, the fact that the inner diameter of the coil is much smaller than the outer diameter and the transmission distance, and believes that the current volume density of the coil can be simplified to the coil line density, thereby reducing the difficulty of calculation. The JA hysteresis model is used to analyze the magnetization intensity of the ferromagnetic material, and a hysteresis model of the ferromagnetic material is established. The equivalent surface current is designed using this model to replace the convergence effect of the ferromagnetic material on the magnetic field, and the magnetic field analysis of the complex structure coil is converted into a synthetic magnetic field analysis excited by multiple currents. The influence of the receiving end current on the synthetic magnetic field is taken into account, and the receiving end current is calculated using the transmitting end current and the equivalent surface current, and the accuracy of the receiving end current calculation result is improved by multiple iterations.

[0041] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 1 is a schematic structural diagram of a wireless power transmission system provided by an embodiment of the present invention;

[0044] Figure 2 This is a flow chart of a method for analyzing a magnetic field in a wireless power transmission system provided by an embodiment of the present invention;

[0045] Figure 3 yes Figure 2 A schematic diagram of the process included in S110;

[0046] Figure 4 This is a schematic diagram of a single-layer transmitting-end coil or receiving-end coil provided by an embodiment of the present invention, wherein the current of the spiral tube body is simplified to the line current;

[0047] Figure 5 This is a schematic diagram of an embodiment of the present invention providing a method of equivalently replacing ferromagnetic materials with surface currents;

[0048] Figure 6 This is a schematic diagram of a simulated magnetic field distribution structure provided by an embodiment of the present invention;

[0049] Figure 7 1 is a schematic structural diagram of a magnetic field analysis device for a wireless power transmission system provided by an embodiment of the present invention;

[0050] Figure 8 A schematic structural diagram of an electronic device of a wireless power transmission system magnetic field analysis device that can be used to implement an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0051] To help those skilled in the art better understand the present invention, the following will provide a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0052] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or devices is not necessarily limited to those steps or devices that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0053] In order to analyze the magnetic field distribution of wireless power transmission systems with different coil structures, the embodiments of the present invention provide the following technical solutions:

[0054] like Figure 1 As shown, Figure 1 This is a schematic diagram of the structure of a wireless power transmission system provided by an embodiment of the present invention. The wireless power transmission system includes a transmitting coil 001, a ferromagnetic material 002, and a receiving coil 003. The number of transmitting coils 001 can be more than one. The wireless power transmission system provided in this figure is suitable for a wireless power transmission coil group used by a power grid distribution system to charge monitoring equipment or inspection robots. In order to facilitate the analysis of the coil magnetic field, the transmitting circuit 004 and the receiving circuit 005 are simplified. The transmitting circuit 004 uses an equivalent power supply U in Instead, the receiving circuit 005 uses a load R load Instead. According to Figure 1 The high-frequency current at the transmitting end passes through the transmitting coil 001, generating an alternating magnetic field. Due to the convergence of the magnetic field by the ferromagnetic material 002, most of the magnetic field passes through the receiving coil 003, generating an induced voltage U at the load end. out .

[0055] like Figure 2 As shown, Figure 2 1 is a flow chart of a method for analyzing a magnetic field in a wireless power transmission system provided by an embodiment of the present invention. The method for analyzing a magnetic field in a wireless power transmission system includes the following steps:

[0056] S110 , calculating the excitation magnetic field of the transmitting-end coil according to the current of the transmitting-end coil.

[0057] Alternatively, as Figure 3 As shown, Figure 3 yes Figure 2 The flowchart of S110 includes the following steps: S110 calculates the excitation magnetic field of the transmitting coil according to the current of the transmitting coil;

[0058] S1101. Determine a line current density of the transmitting coil according to a body current of the transmitting coil and the number of turns of the transmitting coil; wherein the body current of the transmitting coil is simplified to a line current.

[0059] Establish as Figure 1 The rectangular coordinate system shown, refer to Figure 4 , Figure 4 This is a schematic diagram of a single-layer transmitting coil or receiving coil provided by an embodiment of the present invention, which simplifies the body current of the transmitting coil 001 into a line current. Assuming the current of the transmitting coil 001 is I1 and the number of turns of the transmitting coil 001 is N1, the line current density of the transmitting coil 001 is:

[0060]

[0061] in, It is the unit tangential direction of a point (x, y, z) on the inner diameter center of the transmitting coil.

[0062] S1102. Determine the intensity of the magnetic field excited by the transmitting end line segment in the surrounding space according to the linear current density of the transmitting end coil.

[0063] like Figure 1 As shown, the magnetic vector of the magnetic field at any point (x, y, z) around the coil structure is The magnetic vector generated by the transmitting coil at point (x, y, z) for:

[0064]

[0065] Where l' is the length of the transmitting coil, μ0 is the magnetic permeability of free space (μ0 = 4π × 10 -7 H / m)

[0066] The magnetic field strength generated by the transmitting coil at point (x,y,z) for:

[0067]

[0068] in The unit vector from point (x,y,z) to point (x',y',z').

[0069] S1103. Determine the time-varying magnetic field intensity excited by the transmitting end line segment in the surrounding space based on the magnetic field intensity excited by the transmitting end line segment in the surrounding space.

[0070] The above calculations have already obtained the magnetic field strength excited by the transmitting coil in the surrounding space. Now consider how the magnetic field strength changes over time. Since the alternating current in wireless power transmission systems is a high-frequency sinusoidal wave, according to Ampere's law, the magnetic field generated by the current is also a sinusoidal wave of the same frequency. Therefore, the magnetic field strength that changes over time is as follows:

[0071]

[0072] Wherein ω=2πf, f is the resonant frequency of the wireless power transmission system.

[0073] S120. Using a preset hysteresis model, the surface current is equivalent to the ferromagnetic material, and the excitation magnetic field of the equivalent surface current is calculated.

[0074] In order to make the effect of current equivalent substitution more similar to the convergence effect of ferromagnetic material 002 in a magnetic field, it is necessary to first accurately analyze the hysteresis phenomenon of ferromagnetic material 002 in a magnetic field. Currently, the theories studying the hysteresis phenomenon of ferromagnetic materials can be roughly divided into three categories: the first is microscopic hysteresis theory, which explains the hysteresis phenomenon of ferromagnetic materials by analyzing the behavior of magnetic domains and domain walls at the microscopic level; the second is macroscopic hysteresis theory, which explains the hysteresis phenomenon of ferromagnetic materials by analyzing the macroscopic physical quantities of the material, such as hysteresis loops, coercivity, and remanence; and the third is semi-macroscopic hysteresis theory, which combines both microscopic and macroscopic perspectives to describe the hysteresis phenomenon of ferromagnetic materials.

[0075] like Figure 5 As shown, Figure 5 This is a schematic diagram of an embodiment of the present invention providing an equivalent replacement of ferromagnetic material with surface current. The present invention adopts the Jiles-Atherton (JA) hysteresis model in the semi-macroscopic hysteresis theory to analyze the magnetization phenomenon of the ferromagnetic material 002 in the coil structure, and calculates the equivalent surface current based on the analysis results.

[0076] S130 , calculating the synthetic magnetic field of the transmitting end coil and the equivalent surface current according to the exciting magnetic field of the transmitting end coil and the exciting magnetic field of the equivalent surface current.

[0077] S140 , calculating an initial current value of the receiving-end coil according to the synthetic magnetic field of the transmitting-end coil and the equivalent surface current.

[0078] S150 , calculating the composite magnetic field of the transmitting coil, the equivalent surface current, and the receiving coil according to the initial current value of the receiving coil, the current of the transmitting coil, and the equivalent surface current.

[0079] S160 , calculating the secondary value of the current of the receiving-end coil according to the synthetic magnetic field of the transmitting-end coil, the equivalent surface current, and the receiving-end coil.

[0080] S170. Calculate the secondary value of the current of the receiving-end coil multiple times until a relative difference in current density corresponding to the current secondary value of the receiving-end coil calculated this time and the previous calculated current secondary value meets a preset value, and determine that the magnetic field calculated based on the initial current value of the receiving-end coil, the current of the transmitting-end coil, and the equivalent surface current is the composite magnetic field of the transmitting-end coil, the equivalent surface current, and the receiving-end coil.

[0081] Optionally, when the relative difference in current density corresponding to the current secondary values ​​of the receiving end coil calculated this time and last time meets a preset value, the relative difference in current density corresponding to the current secondary values ​​of the receiving end coil calculated this time and last time is not greater than 0.1%.

[0082] Specifically, we first consider the magnetization characteristics of isotropic ferromagnetic materials under DC conditions.

[0083] Under unidirectional magnetization, ferromagnetic materials do not exhibit hysteresis effect. Let the non-hysteresis magnetization intensity at this time be M an , M an and the equivalent magnetic field strength H e The relationship is:

[0084]

[0085] Where Ms is the saturation magnetization, α is the mean field parameter that characterizes the coupling within the magnetic domains, and a is a parameter that characterizes the shape of the material's non-hysteretic magnetization curve and is temperature-dependent. H is the magnetic field intensity, and M is the magnetization intensity of the ferromagnetic material.

[0086] Consider the magnetization characteristics of an isotropic ferromagnetic material under alternating current. At this time, due to the continuous change of the excitation current, the ferromagnetic material exhibits a hysteresis effect in the synthetic magnetic field. Therefore, the magnetization intensity M in the JA hysteresis model is divided into two components, namely the elastic reversible magnetization intensity component M rev and the irreversible magnetization intensity component M due to friction effect irr . M rev Reflects the influence of hysteresis elastic deformation of ferromagnetic materials, M irr It reflects the influence of magnetic domain pinning points formed by discontinuous material structure, and the following relationship exists:

[0087]

[0088] Where c is the reversible magnetic susceptibility.

[0089] According to the three equations defined by the JA hysteresis model, we have:

[0090]

[0091] Where k is the loss coefficient and δ is the directivity coefficient, that is:

[0092]

[0093] According to equations (5) to (7), the differential expression of the magnetization intensity M of the ferromagnetic material with respect to the magnetic field intensity H can be obtained as follows:

[0094]

[0095] Consider a cycle Calculation is performed within. hour, Monotonically decreasing, taking δ = -1, formula (9) can be written as:

[0096]

[0097] The calculated magnetization intensity at this time is M1(x,y,z,t).

[0098] When the time hour, Monotonically increasing, taking δ = 1, formula (9) can be written as:

[0099]

[0100] The calculated magnetization intensity at this time is M2(x,y,z,t).

[0101] Take the average value of magnetization intensity M(x,y,z) within a cycle, that is:

[0102]

[0103] Equivalent surface current density for:

[0104]

[0105] in is the unit vector in the direction of the external normal of the ferromagnetic material surface at point (x, y, z).

[0106] Equivalent surface current The magnetic vector generated at point (x,y,z) for:

[0107]

[0108] Where S' is the area of ​​the equivalent surface current.

[0109] The transmitting coil and the equivalent surface current superimposed magnetic field for:

[0110]

[0111] The initial value of the induced electromotive force e2 induced by the receiving end coil is:

[0112]

[0113] Where S' is the area enclosed by a single-turn coil at the receiving end, and N2 is the number of turns of the coil at the receiving end.

[0114] The receiving coil current I2 is:

[0115]

[0116] The same as the simplified transmitting coil, the number of turns of the receiving coil is taken as N2, then the initial value of the receiving coil line current density is for:

[0117]

[0118] The magnetic vector generated by the receiving coil at point (x, y, z) for:

[0119]

[0120] in, is the current linear density of the receiving coil at point (x, y, z), and l” is the length of the receiving coil.

[0121] The magnetic field strength at any point (x, y, z) in the coil structure is:

[0122]

[0123] in

[0124]

[0125] use Substitute the formula (15) Repeat equations (16) to (21) to calculate the receiving end coil current until the difference between the receiving end coil currents obtained from two consecutive calculations is less than 0.1%, and then obtain the total synthetic magnetic field.

[0126] The technical solution provided by the embodiments of the present invention specifically provides a universal magnetic field distribution characteristics analysis method for coils of different structures in wireless power transmission systems. The present invention is applicable to the analysis of the magnetic field distribution characteristics of coils containing ferromagnetic materials, and can simplify the analysis and calculation of the coil magnetic field, allowing the coil magnetic field distribution to be quickly and conveniently obtained. The present invention is achieved through the following technical solutions:

[0127] A method for analyzing the magnetic field distribution characteristics of different coil structures in a wireless power transmission system includes separately considering the contributions of the transmitting-end coil, ferromagnetic material, and receiving-end coil to the magnetic field in the space surrounding the transmission structure. Since the conduction frequency in the coil is high and the skin effect is significant in the wireless power transmission system, the current in the coil is assumed to be distributed only on the coil surface, and thus the coil body current is simplified to the coil line current. Ferromagnetic materials are magnetized in a magnetic field and have a hysteresis effect, so the surface current distributed along the surface of the ferromagnetic material can be used to equivalently replace the effect of the ferromagnetic material on the synthetic magnetic field. Although the receiving-end current is generated by the magnetic field excited by the transmitting end, there is an induced current in the receiving coil, so the effect of the magnetic field excited by the receiving-end current on the synthetic magnetic field can still be considered.

[0128] The above method considers the contributions of the transmitting coil, ferromagnetic material, and receiving coil to the magnetic field surrounding the transmission structure. First, the magnetic field excited by the transmitting coil is calculated, taking into account the coil line current. Then, using the surface current equivalent to replace the ferromagnetic material, the magnetic field excited by the equivalent surface current is calculated. The magnetic field excited by the transmitting coil and the equivalent surface current is used to calculate the receiving current. Finally, the total composite magnetic field, taking into account all three components, is calculated.

[0129] The above simplification of the coil body current into the coil line current assumes that the current only flows along the edge of the cross section perpendicular to the coil current transmission direction. Considering that the inner diameter of the coil is much smaller than the outer diameter of the coil and the transmission distance, the current flowing along the edge of the coil can be further equivalent to the line current flowing along the center of the coil wire diameter.

[0130] The above-mentioned surface current is equivalent to replacing the ferromagnetic material. First, the magnetization intensity of the ferromagnetic material is analyzed using the Jiles-Atherton (JA) hysteresis model, and a hysteresis model of the ferromagnetic material is established. Then, the hysteresis effect of the ferromagnetic material is replaced by the equivalent surface current. It is assumed here that the direction of the equivalent surface current and the direction of the magnetic lines of force excited by the coil satisfy the right-hand screw theorem, and the surface current is only distributed on the surface of the ferromagnetic material.

[0131] The above calculation of the receiving-end current using the exciting magnetic field of the transmitting-end coil and the equivalent surface current makes the following assumptions:

[0132] 1) Ignoring the time it takes for the transmitter coil to establish a resonant magnetic field, it is assumed that a stable resonant system is established between the transmitter coil and the receiver coil as soon as the power is turned on;

[0133] 2) Ignore the magnetization time of the ferromagnetic material, that is, it is assumed that the ferromagnetic material has reached stable magnetization in the resonant system after the power is turned on;

[0134] 3) It is believed that the initial value of the receiving coil current density can be calculated using the alternating magnetic field generated by the transmitting coil current and the equivalent surface current of the ferromagnetic material;

[0135] 4) It is believed that the magnetic field around the coil can be calculated using the transmitting coil current, the equivalent surface current of the ferromagnetic material, and the initial current of the receiving coil. The current volume density of the receiving coil can be calculated from the magnetic field. The above steps are repeated until the relative difference between the current volume density of the receiving coil obtained from two consecutive calculations is no more than 0.1%;

[0136] It is believed that the receiving end current that satisfies assumption 4) can be used to calculate the synthetic magnetic field of the coil structure.

[0137] The above calculation of the exciting magnetic field of the receiving-end coil current is simplified in the same way as the transmitting-end current. It is assumed that the current of the receiving-end coil can also be simplified to the line current transmitted along the coil.

[0138] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0139] Considering the skin effect of coil current, the fact that the inner diameter of the coil is much smaller than the outer diameter and the transmission distance, it is believed that the current volume density of the coil can be simplified to the coil line density, thereby reducing the calculation difficulty.

[0140] The JA hysteresis model is used to analyze the magnetization intensity of ferromagnetic materials, and a hysteresis model of ferromagnetic materials is established. The model is used to design equivalent surface currents to replace the convergence effect of ferromagnetic materials on the magnetic field, converting the magnetic field analysis of complex coils into a synthetic magnetic field analysis excited by multiple currents.

[0141] The influence of the receiving end current on the synthetic magnetic field is considered, and the receiving end current is calculated using the transmitting end current and the equivalent surface current. The accuracy of the receiving end current calculation result is improved by multiple iterations.

[0142] Optionally, based on the above technical solution, Figure 1 and Figure 4 As shown, the current of the transmitting end coil 001 is simplified to the line current; and / or the current of the receiving end coil 003 is simplified to the line current.

[0143] like Figure 6 As shown, Figure 6 This is a schematic diagram of a simulated magnetic field distribution structure provided by an embodiment of the present invention. The magnetic field distribution of a transmitting coil 001 or a receiving coil 003, comprising a six-turn single solenoid, is calculated using simulation software such as MATLAB. It can be seen that the magnetic field is concentrated within the solenoid and satisfies the right-hand screw rule with the solenoid current. The solenoid parameters for this simulation are shown in Table 1.

[0144] Table 1 Solenoid parameters of wireless power transfer system

[0145]

[0146] Based on the same inventive concept, an embodiment of the present invention also provides a magnetic field analysis device for a wireless power transmission system. Figure 7 As shown, Figure 7 : is a schematic structural diagram of a magnetic field analysis device for a wireless power transmission system provided by an embodiment of the present invention, the magnetic field analysis device for a wireless power transmission system comprising:

[0147] The transmitting end coil magnetic field calculation module 100 is used to calculate the excitation magnetic field of the transmitting end coil according to the current of the transmitting end coil.

[0148] The equivalent surface current magnetic field calculation module 200 is used to use a preset hysteresis model to replace the ferromagnetic material with the surface current and calculate the excitation magnetic field of the equivalent surface current.

[0149] The transmitting end coil and equivalent surface current synthetic magnetic field calculation module 300 is used to calculate the synthetic magnetic field of the transmitting end coil and the equivalent surface current based on the excitation magnetic field of the transmitting end coil and the excitation magnetic field of the equivalent surface current;

[0150] The receiving-end coil current initial value calculation module 400 is used to calculate the receiving-end coil current initial value according to the synthetic magnetic field of the transmitting-end coil and the equivalent surface current.

[0151] The total composite magnetic field calculation module 500 is used to calculate the composite magnetic field of the transmitting coil, the equivalent surface current and the receiving coil according to the initial current value of the receiving coil, the current of the transmitting coil and the equivalent surface current.

[0152] The receiving-end coil current secondary value calculation module 600 calculates the receiving-end coil current secondary value based on the transmitting-end coil, the equivalent surface current and the synthetic magnetic field of the receiving-end coil.

[0153] The synthetic magnetic field confirmation module 700 is used to repeatedly calculate the secondary value of the current of the receiving end coil until the relative difference in current density corresponding to the current secondary value of the receiving end coil calculated this time and the previous calculated current secondary value of the receiving end coil meets a preset value, and then determine that the magnetic field calculated based on the initial current value of the receiving end coil, the current of the transmitting end coil, and the equivalent surface current is the synthetic magnetic field of the transmitting end coil, the equivalent surface current, and the receiving end coil.

[0154] The wireless power transmission system magnetic field analysis device provided in the embodiment of the present invention can execute the wireless power transmission system magnetic field analysis method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0155] Figure 8A schematic diagram of the structure of an electronic device 800 of a wireless power transmission system magnetic field analysis device that can be used to implement an embodiment of the present invention is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0156] like Figure 8 As shown, the electronic device 800 of the wireless power transmission system magnetic field analysis device includes at least one processor 11, and a memory connected to the at least one processor 11, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., wherein the memory stores a computer program that can be executed by at least one processor, and the processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 to the random access memory (RAM) 13. Various programs and data required for the operation of the electronic device 800 can also be stored in the RAM 13. The processor 11, ROM 12 and RAM 13 are connected to each other via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0157] Multiple components in the electronic device 800 of the wireless power transmission system magnetic field analysis device are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a magnetic disk, optical disk, etc.; and a communication unit 19, such as a network card, modem, wireless communication transceiver, etc. The communication unit 19 allows the electronic device 800 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0158] The processor 11 can be various general-purpose and / or specialized processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various specialized artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as the wireless power transmission system magnetic field analysis method.

[0159] In some embodiments, the wireless power transmission system magnetic field analysis method can be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on the electronic device 800 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the wireless power transmission system magnetic field analysis method described above can be performed. Alternatively, in other embodiments, the processor 11 can be configured to execute the wireless power transmission system magnetic field analysis method in any other appropriate manner (for example, by means of firmware).

[0160] Various embodiments of the systems and techniques described herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), system-on-chip systems (SOCs), programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include being implemented in one or more computer programs that are executable and / or interpreted on a programmable system comprising at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0161] Computer programs for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when the computer program is executed by the processor, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The computer program may be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0162] In the context of the present invention, computer-readable storage media can be tangible media that can contain or store a computer program for use with an instruction execution system, device or equipment or used in combination with an instruction execution system, device or equipment. Computer-readable storage media can include but are not limited to electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, computer-readable storage media can be machine-readable signal media. More specific examples of machine-readable storage media can include electrical connections based on one or more lines, portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memory), optical fibers, portable compact disk read-only memories (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0163] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0164] The systems and techniques described herein can be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0165] A computing system may include clients and servers. The clients and servers are typically remote from each other and typically interact via a communication network. This client-server relationship arises through computer programs running on the respective computers, creating a client-server relationship. The server may be a cloud server, also known as a cloud computing server or cloud host. This server is a hosting product within the cloud computing service ecosystem that addresses the management difficulties and limited scalability of traditional physical hosting and VPS services.

[0166] An embodiment of the present invention further provides a computer program product, including a computer program. When the computer program is executed by a processor, the computer program implements the magnetic field analysis method of a wireless power transmission system provided in any embodiment of the present invention.

[0167] The computer program product may be implemented by writing computer program code for performing the operations of the present invention in one or more programming languages, or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0168] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present invention can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved. This is not limited herein.

[0169] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A method for analyzing the magnetic field of a wireless power transmission system, wherein the wireless power transmission system includes a transmitting coil, a ferromagnetic material, and a receiving coil, characterized in that: include: Calculate the exciting magnetic field of the transmitting end coil according to the current of the transmitting end coil; Using the preset hysteresis model, the surface current is equivalent to the ferromagnetic material, and the excitation magnetic field of the equivalent surface current is calculated; Calculating a synthetic magnetic field of the transmitting end coil and the equivalent surface current based on the exciting magnetic field of the transmitting end coil and the exciting magnetic field of the equivalent surface current; Calculating an initial current value of the receiving-end coil according to a synthetic magnetic field of the transmitting-end coil and the equivalent surface current; Calculating a composite magnetic field of the transmitting-end coil, the equivalent surface current, and the receiving-end coil according to an initial current value of the receiving-end coil, the current of the transmitting-end coil, and the equivalent surface current; Calculating a secondary value of the current of the receiving-end coil according to the synthetic magnetic field of the transmitting-end coil, the equivalent surface current, and the receiving-end coil; The secondary value of the current of the receiving-end coil is calculated multiple times until a relative difference in current density corresponding to the current secondary value of the receiving-end coil calculated this time and the previous calculated current secondary value meets a preset value, and a magnetic field calculated based on the initial current value of the receiving-end coil, the current of the transmitting-end coil, and the equivalent surface current is determined to be a composite magnetic field of the transmitting-end coil, the equivalent surface current, and the receiving-end coil.

2. The method for analyzing the magnetic field of a wireless power transmission system according to claim 1, wherein: The current of the transmitting end coil is simplified to line current; And / or, the current of the receiving-end coil is simplified to the line current.

3. The method for analyzing the magnetic field of a wireless power transmission system according to claim 1, wherein: Before calculating the exciting magnetic field of the transmitting coil according to the current of the transmitting coil, it also includes: After the power is turned on, a resonant system is formed between the transmitting end coil and the receiving end coil; After the power is turned on, the ferromagnetic material is completely magnetized in the resonant system.

4. The method for analyzing the magnetic field of a wireless power transmission system according to claim 1, wherein: When the relative difference in current density corresponding to the current secondary value of the receiving end coil calculated this time and last time meets the preset value, the relative difference in current density corresponding to the current secondary value of the receiving end coil calculated this time and last time is not greater than 0.1%.

5. The method for analyzing the magnetic field of a wireless power transmission system according to claim 2, wherein: Calculating the exciting magnetic field of the transmitting coil based on the current of the transmitting coil includes: Determining the line current density of the transmitting end coil according to the body current of the transmitting end coil and the number of turns of the transmitting end coil; wherein the body current of the transmitting end coil is simplified to the line current; The intensity of the magnetic field excited by the transmitting-end coil in the surrounding space is determined according to the linear current density of the transmitting-end coil.

6. The method for analyzing the magnetic field of a wireless power transmission system according to claim 5, wherein: After determining the magnetic field intensity excited by the transmitting-end coil in the surrounding space according to the linear current density of the transmitting-end coil, the method further includes: The intensity of the magnetic field excited by the transmitting end coil in the surrounding space and varying with time is determined according to the intensity of the magnetic field excited by the transmitting end coil in the surrounding space.

7. The method for analyzing the magnetic field of a wireless power transmission system according to claim 1, wherein: Using the preset hysteresis model, the surface current is equivalent to the ferromagnetic material, and the excitation magnetic field of the equivalent surface current is calculated, including: The Jiles-Atherton (JA) hysteresis model is used to replace the ferromagnetic material with the surface current, and the exciting magnetic field of the equivalent surface current is calculated.

8. A magnetic field analysis device for a wireless power transmission system, characterized in that: include: The transmitting end coil magnetic field calculation module is used to calculate the exciting magnetic field of the transmitting end coil according to the current of the transmitting end coil; The equivalent surface current magnetic field calculation module is used to use the preset hysteresis model to replace the ferromagnetic material with the surface current and calculate the excitation magnetic field of the equivalent surface current; a module for calculating a synthetic magnetic field of a transmitting end coil and an equivalent surface current, configured to calculate a synthetic magnetic field of the transmitting end coil and the equivalent surface current based on the excitation magnetic field of the transmitting end coil and the excitation magnetic field of the equivalent surface current; A receiving-end coil current initial value calculation module, configured to calculate the receiving-end coil current initial value based on the synthetic magnetic field of the transmitting-end coil and the equivalent surface current; a total synthetic magnetic field calculation module, configured to calculate the synthetic magnetic field of the transmitting-end coil, the equivalent surface current, and the receiving-end coil based on the initial current value of the receiving-end coil, the current of the transmitting-end coil, and the equivalent surface current; a receiving-end coil current secondary value calculation module, which calculates the receiving-end coil current secondary value according to the transmitting-end coil, the equivalent surface current and the synthetic magnetic field of the receiving-end coil; The synthetic magnetic field confirmation module is used to calculate the secondary value of the current of the receiving end coil multiple times until the relative difference in current density corresponding to the current secondary value of the receiving end coil calculated this time and the previous calculated current secondary value meets a preset value, and determine that the magnetic field calculated based on the initial current value of the receiving end coil, the current of the transmitting end coil and the equivalent surface current is the synthetic magnetic field of the transmitting end coil, the equivalent surface current and the receiving end coil.

9. An electronic device, characterized in that: include: at least one processor; as well as a memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can perform the wireless power transmission system magnetic field analysis method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the wireless power transmission system magnetic field analysis method according to any one of claims 1 to 7 when executed.

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