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

Abstract

The invention discloses a wireless power transmission system magnetic field analysis method, device and equipment and a storage medium. The method comprises the following steps: calculating a synthetic magnetic field of a transmitting end coil and an equivalent surface current according to excitation magnetic fields of the transmitting end coil and the equivalent surface current; calculating an initial current value of a receiving end coil according to the resultant magnetic field; calculating a current secondary value of the receiving end coil according to a synthetic magnetic field of the transmitting end coil, the equivalent surface current and the receiving end coil; calculating the current secondary value of the receiving end coil for multiple times until the current density relative difference value corresponding to the current secondary value of the receiving end coil calculated at the current time and the current density relative difference value corresponding to the current secondary value of the receiving end coil calculated at the last time meet a preset value; and determining a magnetic field calculated according to the current initial value of the receiving end coil, the current of the transmitting end coil and the equivalent surface current as a synthetic magnetic field of the transmitting end coil, the equivalent surface current and the receiving end coil. According to the technical scheme, the magnetic field distribution of wireless power transmission systems with different coil structures is analyzed.

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 a magnetic field of a wireless power transmission system. Background Art

[0002] The development of wireless power transmission technology provides a new solution for the power supply of data acquisition devices and power inspection robots in the fully digital power distribution system, that is, to achieve contactless charging from power supply to load by wireless power transmission. Mainstream wireless power transmission technologies include electromagnetic induction wireless power transmission, magnetic coupling resonance wireless power transmission, and microwave wireless power transmission.

[0003] Among them, since electromagnetic induction wireless power transmission mainly relies on the induced voltage or induced charge generated between coils or plates for power transmission, the power transmission distance of this type of technology is short. Considering the insulation requirements and power supply flexibility of the power distribution system, inductive wireless power transmission is not convenient for powering equipment such as power inspection robots. Microwave wireless power transmission technology requires the setting of specific transmitting antennas and receiving antennas to transmit power in a fixed direction and route, and 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 coil and the receiving coil 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. The magnetic field analysis of coils is studied in depth based on the equations. Due to the complexity of the calculation of Maxwell's equations, it is time-consuming and laborious to analyze and study different coil structures from the most basic theory, which is not conducive to the design and improvement of wireless power transmission systems with specific requirements. Therefore, a method for analyzing the magnetic field distribution characteristics of different coil structures of wireless power transmission systems is considered to provide a general research method for coils of different structures, which is conducive to the rapid design of wireless power transmission systems that meet the 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 of a wireless power transmission system is provided. The wireless power transmission system includes a transmitting end coil, a ferromagnetic material, and a receiving end coil. The method for analyzing a magnetic field of 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 exciting magnetic field of the equivalent surface current is calculated;

[0009] Calculate 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;

[0010] Calculating the initial value of the current of the receiving end coil according to the 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 the initial current value of the receiving-end coil, the current of the transmitting-end coil and the equivalent surface current;

[0012] Calculate 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;

[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 secondary value of the current of the receiving-end coil calculated this time and last time 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 fully 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 line current density of the transmitting end coil.

[0023] Optionally, after determining the magnetic field intensity induced by the transmitting end line segment in the surrounding space according to the line 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.

[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 magnetic field analysis device for 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 transmitting end coil and equivalent surface current synthetic magnetic field calculation module, used to calculate the synthetic magnetic field of the transmitting end coil and the equivalent surface current according to 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, used to calculate the current initial value of the receiving-end coil according to the synthetic magnetic field of the transmitting-end coil and the equivalent surface current;

[0032] A total synthetic magnetic field calculation module, used to calculate the synthetic magnetic field of the transmitting end coil, the equivalent surface current and the receiving end coil according to 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 current secondary value of the receiving-end coil 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 for multiple times until the relative difference in current density corresponding to the secondary value of the current of the receiving end coil calculated this time and the previous time meets the 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 execute the magnetic field analysis method of the wireless power transmission system 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 any of the wireless power transmission system magnetic field analysis methods described in the embodiments 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, and 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 the model to replace the convergence effect of the ferromagnetic material on the magnetic field, and the magnetic field analysis of the complex structure of the 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 considered, 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 contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily 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 is a structural schematic diagram of a wireless power transmission system provided by an embodiment of the present invention;

[0044] Figure 2 is a flow chart of a method for analyzing a magnetic field of 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 It is a schematic diagram of simplifying the spiral tube current of a single-layer transmitting-end coil or a receiving-end coil provided by an embodiment of the present invention into a line current;

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

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

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

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

[0051] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution in the embodiment of the present invention will be described clearly and completely in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0052] It should be noted that the terms "first", "second", etc. in the specification 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 data 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 embodiment of the present invention provides the following technical solutions:

[0054] like Figure 1 As shown, Figure 1 004 and the receiving end circuit 005 are simplified. The transmitting end 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 end 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 end 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 of a wireless power transmission system provided by an embodiment of the present invention. The method for analyzing a magnetic field of a wireless power transmission system comprises the following steps:

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

[0057] Alternatively, if Figure 3 As shown, Figure 3 yes Figure 2 The flowchart of S110 includes: S110 calculates the excitation magnetic field of the transmitting end coil according to the current of the transmitting end coil, including:

[0058] S1101. Determine 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.

[0059] Establish as Figure 1 The rectangular coordinate system shown in Figure 4 , Figure 4 It is a schematic diagram of simplifying the helical tube body current of a single-layer transmitting coil or receiving coil provided by an embodiment of the present invention into a line current, and simplifies the body current of the transmitting coil 001 into a line current. Assuming that 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 tangent direction of a point (x, y, z) at the center of the inner diameter of the transmitting coil.

[0062] S1102. Determine the intensity of the magnetic field induced 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 is the unit vector from point (x,y,z) to point (x',y',z').

[0069] S1103. Determine the intensity of the magnetic field excited by the transmitting end line segment in the surrounding space and varying with time.

[0070] The above calculations have obtained the magnetic field strength excited by the transmitting coil in the surrounding space. Now consider the change of magnetic field strength over time. Since the alternating current of the wireless power transmission system is a high-frequency sine wave, according to Ampere's law, the magnetic field excited by the current is also a sine 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 replace 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 closer to the convergence of ferromagnetic material 002 in a magnetic field, we must first accurately analyze the hysteresis phenomenon of ferromagnetic material 002 in a magnetic field. At present, the theories studying the hysteresis phenomenon of ferromagnetic materials can be roughly divided into three categories: the first is the 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 the macroscopic hysteresis theory, which explains the hysteresis phenomenon of ferromagnetic materials by analyzing the macroscopic physical quantities of the material, such as hysteresis loops, coercive force, remanence, etc.; the third is the semi-macroscopic hysteresis theory, which combines the microscopic and macroscopic perspectives to describe the hysteresis phenomenon of ferromagnetic materials.

[0075] like Figure 5 As shown, Figure 5 It is a schematic diagram of an embodiment of the present invention that provides 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 the initial value of the current 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 synthetic magnetic field of the transmitting end coil, the equivalent surface current and the receiving end coil according to the initial value of the current of the receiving end coil, the current of the transmitting end 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, calculating the secondary value of the current of the receiving end coil multiple times until the relative difference in current density corresponding to the secondary value of the current of the receiving end coil calculated this time and the previous time meets the preset value, and determining that the magnetic field calculated based on the initial value of the current 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] Among them, Ms is the saturation magnetization, α is the mean field parameter that characterizes the internal coupling of the magnetic domain, a is the parameter that characterizes the shape of the non-hysteresis magnetization curve of the material and is related to temperature. 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 an alternating current. At this time, due to the constant 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] Among them, 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 is obtained as follows:

[0094]

[0095] Consider a cycle Calculation is performed within . hour, Monotonically decreasing, taking δ = -1, equation (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, equation (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 line density of the receiving end coil at point (x, y, z), and l” is the length of the receiving end coil.

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

[0122]

[0123] in

[0124]

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

[0126] The technical solution provided by the embodiment of the present invention specifically provides a universal magnetic field distribution characteristic analysis method for coils of different structures in wireless power transmission systems. The present invention is applicable to the analysis of magnetic field distribution characteristics of coils with ferromagnetic materials, which can simplify the analysis and calculation of the coil magnetic field and quickly and conveniently obtain the coil magnetic field distribution. The present invention is implemented by the following technical solution:

[0127] A method for analyzing the magnetic field distribution characteristics of different coil structures of a wireless power transmission system includes respectively considering the contribution of the transmitting end coil, ferromagnetic material and receiving end coil to the magnetic field in the space around the transmission structure; since in the wireless power transmission system, the conduction frequency in the coil is relatively high and the skin effect is significant, it is considered that the current in the coil is only distributed on the coil surface, so the coil body current is simplified to the coil line current; the ferromagnetic material is magnetized in the magnetic field and has 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-mentioned consideration of the contribution of the transmitting coil, ferromagnetic material and receiving coil to the magnetic field around the transmission structure first calculates the exciting magnetic field of the transmitting coil considering the coil line current, and then uses the surface current to replace the ferromagnetic material to calculate the exciting magnetic field of the equivalent surface current. The receiving current is calculated using the magnetic field excited by the transmitting coil and the equivalent surface current, and finally the total composite magnetic field considering the three parts of the structure 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 on 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 will make the following assumptions:

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

[0133] 2) The magnetization time of the ferromagnetic material is ignored, 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 considered 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, and the current volume density of the receiving coil can be calculated from the magnetic field, and the above steps are repeated until the relative difference between the current volume density of the receiving coil calculated twice 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, and it is considered 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 beneficial effects of the embodiments of the present invention are as follows:

[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 difficulty of calculation.

[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 equivalent surface current is designed using this model to replace the convergence effect of ferromagnetic materials on the magnetic field, converting the magnetic field analysis of coils with complex structures 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, and 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, wherein the magnetic field distribution of the transmitting end coil 001 or the receiving end coil 003 including a 6-turn single solenoid coil calculated using simulation software such as MATLAB, and it can be seen that the magnetic field is concentrated inside the solenoid and satisfies the right-hand screw rule with the solenoid current. The solenoid parameters of the simulation setting are shown in Appendix 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 diagram of the structure of a magnetic field analysis device for a wireless power transmission system provided by an embodiment of the present invention, and the magnetic field analysis device for a wireless power transmission system includes:

[0147] The transmitting end coil magnetic field calculation module 100 is used to calculate the exciting 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 according to the exciting magnetic field of the transmitting end coil and the exciting 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 end coil, the equivalent surface current and the receiving end coil according to the initial current value of the receiving end coil, the current of the transmitting end 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 according to 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 calculate the secondary value of the current of the receiving end coil for multiple times until the relative difference in current density corresponding to the secondary value of the current of the receiving end coil calculated this time and the previous time meets the preset value, and determine that the magnetic field calculated based on the initial value of the current 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, workbenches, 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. In RAM 13, various programs and data required for the operation of the electronic device 800 can also be stored. The processor 11, ROM 12 and RAM 13 are connected to each other through 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, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 800 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0158] The processor 11 may be a variety of general and / or special 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 dedicated 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 a wireless power transmission system magnetic field analysis method.

[0159] In some embodiments, the wireless power transmission system magnetic field analysis method may 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 may 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 may be performed. Alternatively, in other embodiments, the processor 11 may be configured to perform the wireless power transmission system magnetic field analysis method in any other appropriate manner (e.g., by means of firmware).

[0160] Various embodiments of the systems and techniques described above 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), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a dedicated or general 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, so that when the computer program is executed by the processor, the functions / operations specified in the flow chart and / or block diagram are implemented. The computer program may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

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

[0163] To provide interaction with a user, the systems and techniques described herein may 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 a pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices may also be used to provide interaction with the user; for example, the feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form (including acoustic input, voice input, or tactile input).

[0164] The systems and techniques described herein may be implemented in a computing system that includes backend 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 frontend components (e.g., a user computer with a graphical user interface or a 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 backend components, middleware components, or frontend components. The components of the system may 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 a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The client and server relationship is generated by computer programs running on the corresponding computers and having a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or cloud host, which is a host product in the cloud computing service system to solve the defects of difficult management and weak business scalability in traditional physical hosts and VPS services.

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

[0167] In the process of implementation, the computer program product can be written in one or more programming languages ​​or a combination thereof to perform the computer program code of the present invention, including object-oriented programming languages, such as Java, Smalltalk, C++, and conventional procedural programming languages, such as "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computer (for example, using an Internet service provider to connect through the Internet).

[0168] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0169] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope 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 comprises a transmitting end coil, a ferromagnetic material and a receiving end 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 exciting magnetic field of the equivalent surface current is calculated; Calculate 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; Calculating the initial value of the current of the receiving end coil according to the 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 the initial current value of the receiving-end coil, the current of the transmitting-end coil and the equivalent surface current; Calculate 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; 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 secondary value of the current of the receiving-end coil calculated this time and last time 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, characterized in that: 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 magnetic field of a wireless power transmission system according to claim 1, characterized in that: Before calculating the exciting magnetic field of the transmitting end coil according to the current of the transmitting end 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 fully magnetized in the resonant system.

4. The method for analyzing magnetic field of a wireless power transmission system according to claim 1, characterized in that: When the relative difference of 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 of 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 magnetic field of a wireless power transmission system according to claim 2, characterized in that: Calculating the exciting magnetic field of the transmitting coil according to 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 line segment in the surrounding space is determined according to the line current density of the transmitting end coil.

6. The method for analyzing magnetic field of a wireless power transmission system according to claim 5, characterized in that: After determining the magnetic field intensity induced 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: The intensity of the magnetic field excited by the transmitting end line segment in the surrounding space and varying with time is determined.

7. The method for analyzing magnetic field of a wireless power transmission system according to claim 1, characterized in that: 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 transmitting end coil and equivalent surface current synthetic magnetic field calculation module, used to calculate the synthetic magnetic field of the transmitting end coil and the equivalent surface current according to 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, used to calculate the current initial value of the receiving-end coil according to the synthetic magnetic field of the transmitting-end coil and the equivalent surface current; A total synthetic magnetic field calculation module, used to calculate the synthetic magnetic field of the transmitting end coil, the equivalent surface current and the receiving end coil according to 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 current secondary value of the receiving-end coil 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 for multiple times until the relative difference in current density corresponding to the secondary value of the current of the receiving end coil calculated this time and the previous time meets the 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 execute the magnetic field analysis method for a wireless power transmission system 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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