A design method for conical spiral coil in wireless power transmission system

Abstract

The present invention discloses a design method for a conical spiral coil in a wireless power transmission system. The method determines the magnetic flux expression of the system by modeling and calculating the system of the double-plane circular coil; analyzes the relationship between the magnetic flux and the radius of the transmitting and receiving coils, and defines the concept of the optimal radius; explores the change of the optimal transmitting and receiving radius with the transmission distance; fits the expression between the optimal radius of the single-turn transmitting and receiving coils and the transmission distance; calculates the optimal radius value at the corresponding distance according to the actual transmission distance of each turn of the conical coil in the application, so that all the wire turn radii of the conical spiral coil obtain the optimal value, thereby designing an optimized conical spiral coil. The present invention optimizes the parameter design of the conical spiral coil, and improves the transmission power of the wireless power transmission system through the design of the conical spiral coil.

Description

Technical Field

[0001] The invention belongs to the technical field of wireless power transmission, and in particular relates to a design method of a conical spiral coil in a wireless power transmission system. Background Art

[0002] Wireless Power Transfer (WPT) technology is a new type of contactless charging technology. Through certain technical means, it converts electrical energy into space energy carriers such as electromagnetic waves, microwaves and lasers and transmits them to load devices, thus getting rid of the constraints of cables, making the distribution of electrical energy more diversified, and improving the flexibility and convenience of electrical equipment. Its emergence has provided new ideas for the endurance issues of various electronic consumer products such as electric vehicles, smart wearable devices and implantable medical devices.

[0003] The magnetically coupled resonant wireless power transmission technology proposed by the Massachusetts Institute of Technology has been widely used, especially in the field of electric vehicles, due to its advantages such as long transmission distance, high transmission efficiency, and high transmission power. Since electric vehicles require long driving range and fast charging, the wireless power transmission system is required to have better transmission performance and be able to maximize the transmission power of the system. For this reason, various coil topologies have been proposed, including planar circular, planar D-type, spatial cylindrical, and spatial conical spiral coil structures. The spatial spiral coil structure has a better coupling effect than the planar spiral structure and is a commonly used topology in the wireless charging system of electric vehicles. However, it also has the problems of large space occupation, high consumables usage, and more magnetic leakage. The spatial spiral coil structure needs to be further optimized. Summary of the invention

[0004] The purpose of the present invention is to provide a design method for a conical spiral coil in a wireless power transmission system, which is suitable for the design of a conical spiral coil in a wireless power transmission system including a conical spiral transmitting coil and a planar circular receiving coil, or a planar circular transmitting coil and a conical spiral receiving coil. Through the design of the conical spiral coil, the transmission power of the wireless power transmission system is improved.

[0005] The technical solution to achieve the purpose of the present invention is as follows: a design method for a conical spiral coil in a wireless power transmission system, wherein the specific design process of the optimized conical spiral coil is as follows:

[0006] Step 1, modeling and calculating a wireless power transmission system including a planar circular transmitting coil and a planar circular receiving coil, and determining a magnetic flux function of the system of the double planar circular coils;

[0007] Step 2: When the number of turns and the turn spacing of the transmitting coil, the inner diameter, the number of turns, the turn spacing of the receiving coil and the transmission distance are determined, the relationship between the magnetic flux and the radius of the transmitting coil and the relationship between the magnetic flux and the radius of the receiving coil are analyzed;

[0008] Step 3: Under different transmission distances, establish and analyze the relationship between the optimal transmission radius of the transmitting coil and the optimal receiving radius of the receiving coil as the transmission distance increases;

[0009] Step 4, quantifying the relationship between the optimal radius of a single-turn transmitting coil and the transmission distance, and quantifying the relationship between the optimal radius of a single-turn receiving coil and the transmission distance;

[0010] Step 5: Based on the quantitative relationship between the optimal transmitting or receiving radius and the transmission distance in the system of dual-planar circular coils, design the conical spiral coil transmitting coil and the conical spiral receiving coil in the system composed of the flat coil and the conical spiral coil.

[0011] Compared with the prior art, the present invention has the following significant advantages:

[0012] The present invention optimizes the design of all wire turn radii of the conical spiral coil based on the theory of the optimal radius of the coil, and maximizes the transmission power of the system without changing the original structure. The optimized conical spiral coil has a better magnetic field focusing effect, and the leakage magnetic field in the surrounding environment is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the equivalent model diagram of the circular coil wireless power transmission system.

[0014] Figure 2 It is the curve of the system magnetic flux changing with the outer radius of the transmitting coil.

[0015] Figure 3 It is the curve of the system magnetic flux changing with the inner radius of the receiving coil.

[0016] Figure 4 This is a graph showing the relationship between the optimal launch radius and maximum magnetic flux and the transmission distance.

[0017] Figure 5 This is a graph showing the relationship between the optimal receiving radius and the maximum magnetic flux and the transmission distance.

[0018] Figure 6 It is the fitting curve of the optimal radius of a single-turn transmitting coil and the transmission distance.

[0019] Figure 7 It is the fitting curve of the optimal radius of a single-turn receiving coil and the transmission distance.

[0020] Figure 8 It is the equivalent model diagram of the optimized conical spiral transmitting coil wireless power transmission system.

[0021] Fig. 9 It is the equivalent model diagram of the optimized conical spiral receiving coil wireless power transmission system.

[0022] Fig.10 It is the simulation model of cylindrical and conical spiral transmitting coil wireless power transmission system; (a) cylindrical spiral transmitting coil WPT system, (b) optimized conical spiral transmitting coil WPT system.

[0023] Fig.11 Figure 2 is the electromagnetic environment distribution of cylindrical and conical spiral transmitting coil wireless power transmission systems; (a) the electromagnetic environment of the cylindrical spiral transmitting coil WPT system, (b) the electromagnetic environment of the optimized conical spiral transmitting coil WPT system. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0025] The present invention is based on the principle of magnetically coupled resonant wireless power transmission technology. Through modeling and magnetic field analysis of a circular coil wireless power transmission system, a theory of optimal radius of a circular transmitting coil and a receiving coil is proposed. The relationship between the optimal transmitting radius, the optimal receiving radius and the transmission distance of the system is explored and quantified. By optimizing the conical space spiral coil, the radius of each turn of the transmitting or receiving coil is limited to the optimal value under the transmission distance. By optimizing the design of the coil's own parameters, the transmission power of the system is maximized.

[0026] The present invention is based on the optimal radius theory of the coil in the wireless power transmission system, and is applicable to the design of a wireless power transmission system including a conical spiral transmitting coil and a planar circular receiving coil, and a wireless power transmission system including a planar circular transmitting coil and a conical spiral receiving coil. The specific design process of the optimized conical spiral coil is as follows:

[0027] Step 1, modeling and calculating a wireless power transmission system including a planar circular transmitting coil and a planar circular receiving coil, and determining a magnetic flux function of the system of the double planar circular coils;

[0028] like Figure 1 As shown in the figure, an equivalent model of a wireless power transmission system consisting of a planar circular transmitting and receiving coil is given. The radius of the outermost turn of the transmitting coil is R 1 , the number of turns is n 1 , the turn spacing is d 1 , the radius of the innermost turn is R 1 -(n 1 -1)d 1 , the current passing through the coil is I, according to the principle of upward magnetic flux, the current is counterclockwise; the inner radius of the receiving coil is r2 , the number of turns is n 2 , the turn spacing is d 2 , the outer radius is r 2 +(n 2 -1)d 2 , the transmission distance between the transmitting and receiving coils is H.

[0029] Calculate the spatial magnetic field generated by the circular transmitting coil, integrate the magnetic induction intensity along the z-axis (only the component in the z-axis direction is perpendicular to the receiving coil) in the circular area surrounded by each turn of the receiving coil to obtain the magnetic flux passing through the receiving coil. 2 The total flux linkage Ψ of the system is obtained by superimposing the magnetic flux of the coil turns:

[0030]

[0031] In formula (1), Ψ is the total flux of the system, n 1 is the number of turns of the transmitting coil, n 2 is the number of turns of the receiving coil, d 1 is the turn spacing of the transmitting coil, d 2 is the turn spacing of the receiving coil, R 1 is the outer radius of the transmitting coil, r 2 is the inner radius of the receiving coil, R(i) is the i-th (i=1,2,...,n 1 ) turns of the transmitting coil (counting from the inside to the outside), R(j) is the radius of the jth (j=1,2,...,n 2 ) turns of the receiving coil radius (counting from the inside to the outside), μ 0 is the vacuum permeability, which is 4π×10 -7 Wb / (A·m), I is the current flowing through the transmitting coil, H is the transmission distance of the system, r is the integral variable, and its integral range is 0~R(j), E(k) and K(k) are the first and second kind complete elliptic integrals respectively.

[0032] Step 2: Based on the total flux function in step 1, when other parameters (number of turns and turn spacing of the transmitting coil, inner diameter, number of turns, turn spacing and transmission distance of the receiving coil) are determined, the relationship between the flux and the radius of the transmitting coil and the relationship between the flux and the radius of the receiving coil are analyzed;

[0033] Based on formula (1), when other parameters (number of turns and turn spacing of the transmitting coil, inner diameter of the receiving coil, number of turns, turn spacing and transmission distance) are determined, the total flux linkage Ψ and the outer radius R of the transmitting coil are analyzed. 1The relationship between the total magnetic flux Ψ and the inner radius r of the receiving coil is defined as the optimal transmitting radius. When other parameters (inner diameter, number of turns, turn spacing of the transmitting coil, number of turns, turn spacing of the receiving coil and transmission distance) are determined, the total magnetic flux Ψ and the inner radius r of the receiving coil are analyzed. 2 The relationship between the inner radius of the receiving coil that can make the system magnetic flux reach the maximum value is defined as the optimal receiving radius.

[0034] (1) Changes of magnetic flux with the outer radius of the transmitting coil

[0035] Set the transmitting coil parameters, including the turn spacing d 1 、Number of turns n 1 , input current I; receiving coil parameters, including inner radius r 2 、Number of turns n 2 , turn spacing d 2 Substituting the distance H between the two coils into formula (1), we can obtain the flux linkage Ψ with the outer radius R of the transmitting coil: 1 The curve, along with R 1 The increase of the flux first increases to the maximum value and then decreases. The R corresponding to the maximum value of the flux 1 That is the optimal transmitting radius R of the transmitting coil OT . Figure 2 This is an example of a curve showing the change of magnetic flux with the outer radius of the transmitting coil. Its parameter d 1 =0.002m,n 1 =10, I = 5A, r 2 =0.01m,n 2 =10,d 2 =0.002m and H = 0.1m. It can be seen from the figure that the variation curve of magnetic flux with the outer radius of the transmitting coil is a single peak distribution. When the outer radius of the transmitting coil is 0.156m, the magnetic flux reaches a maximum value of 1.49×10 -6 Wb, that is, the optimal launch radius of the system under this parameter is 0.156m.

[0036] (2) Changes in flux linkage with the inner radius of the receiving coil

[0037] Set the transmitting coil parameters, including the inner radius r 1 , turn spacing d 1 、Number of turns n 1 , input current I; receiving coil parameters, including the number of turns n 2 , turn spacing d 2 Substituting the distance H between the two coils into formula (1), we can obtain the flux linkage Ψ with the inner radius r of the receiving coil: 2 The curve, as r 2 The increase of the magnetic flux increases to the maximum value first and then decreases. The r corresponding to the maximum value of the magnetic flux 2 That is the optimal receiving radius r of the receiving coilOR . Figure 3 This is an example of a curve showing the change of magnetic flux with the inner radius of the receiving coil. Its parameter r 1 =0.01m,d 1 =0.002m,n 1 =10, I = 5A, n 2 =10,d 2 =0.002m and H = 0.1m. It can be seen from the figure that the variation curve of flux linkage with the inner radius of the receiving coil is also a single peak distribution. When the inner radius of the receiving coil is 0.135m, the maximum value of flux linkage is 1.49×10 - 6 Wb, that is, the optimal receiving radius of the system under this parameter is 0.135m.

[0038] Step 3: Under different transmission distances, establish and analyze the relationship between the optimal transmission radius of the transmitting coil and the optimal receiving radius of the receiving coil as the transmission distance increases;

[0039] Based on the parameters in step 2, the transmission distance of the system is taken as an eigenvalue every 1 cm from 1 to 20 cm, and a total of 20 distance eigenvalues ​​are taken. The optimal radius corresponding to each distance eigenvalue is calculated according to formula (1), and 20 groups of data are calculated. Then, the fitting curve is used to explore the change of the optimal transmitting radius of the transmitting coil as the transmission distance increases; and the change of the optimal receiving radius of the receiving coil as the transmission distance increases.

[0040] (1) Changes in the optimal transmission radius with transmission distance

[0041] Take a value of 1 cm at a transmission distance from 1 to 20 cm, and take 20 distance values ​​in total, and calculate the optimal transmission radius value under different transmission distances. Figure 4 The curves of the optimal radius of the transmitting coil and the maximum value of the magnetic flux change with the transmission distance of the system. The vertical axis on the left side of the figure is the optimal transmitting radius. The black circle curve in the figure is the relationship between the optimal transmitting radius and the transmission distance. It can be seen that the two are approximately positively correlated. As the transmission distance increases, the optimal transmitting radius also increases. The vertical axis on the right side of the figure is the maximum value of the magnetic flux corresponding to the optimal transmitting radius. The square mark in the figure is the relationship between the maximum value of the magnetic flux and the transmission distance. It can be seen that the two are negatively correlated. As the transmission distance increases, the maximum value of the magnetic flux decreases rapidly, which also verifies the sensitivity of the wireless power transmission system to the transmission distance.

[0042] (2) Changes in the optimal receiving radius with transmission distance

[0043] Take a value of 1 cm at a transmission distance from 1 to 20 cm, and take 20 distance values ​​in total, and calculate the optimal receiving radius value under different transmission distances. Figure 5The curves of the optimal radius of the receiving coil and the maximum value of the magnetic flux change with the transmission distance of the system. The vertical axis on the left side of the figure is the optimal transmission radius. The black circle curve in the figure is the relationship between the optimal transmission radius and the transmission distance. It can be seen that the two are approximately positively correlated. As the transmission distance increases, the optimal transmission radius also increases. The vertical axis on the right side of the figure is the maximum value of the magnetic flux corresponding to the optimal transmission radius. The red square in the figure is the relationship between the maximum value of the magnetic flux and the transmission distance. It can be seen that the two are negatively correlated. As the transmission distance increases, the maximum value of the magnetic flux decreases rapidly.

[0044] Step 4: quantify the relationship between the optimal radius of the single-turn transmitting coil and the transmission distance through the curve fitting toolbox in Matlab, and quantify the relationship between the optimal radius of the single-turn receiving coil and the transmission distance;

[0045] It can be seen from step 3 that the optimal transmitting radius and the optimal receiving radius both change with the change of the transmission distance. Taking the number of turns of the transmitting coil as 1, the relationship between the optimal radius of a single-turn transmitting coil and the transmission distance is explored and quantified, and the quantitative expressions of the two are given; taking the number of turns of the receiving coil as 1, the relationship between the optimal radius of a single-turn receiving coil and the transmission distance is explored and quantified, and the quantitative expressions of the two are given.

[0046] (1) Quantitative relationship between optimal transmission radius and transmission distance

[0047] Depend on Figure 4 It can be seen that the optimal radius of the transmitting coil is directly proportional to the transmission distance, and the relationship between the two can be further quantified. Figure 6 This is the relationship curve between the optimal radius of a single-turn transmitting coil and the transmission distance fitted by Matlab. The transmission distance is between 0.01m and 0.2m and 20 distance values ​​are taken. In order to make the scattered points distributed on the fitting curve as much as possible, the linear cubic multi-form approximation fitting method is used to obtain the optimal radius R of the single-turn transmitting coil. OT The expression of the system transmission distance H is:

[0048] R OT =-6.279H 3 +2.503H 2 +1.088H+0.01553

[0049] Among them, the sum and variance SSE in the fitting is 9.398e-06, close to 0; the coefficient of determination R-square is 0.9999, close to 1, indicating that the above formula achieves the optimal radius R for a single-turn transmitting coil. OT The relationship between the two and the system transmission distance H is well fitted.

[0050] (2) Quantitative relationship between optimal receiving radius and transmission distance

[0051] Depend on Figure 5 It can be seen that the optimal radius of the receiving coil is directly proportional to the transmission distance, and the relationship between the two can be further quantified. Figure 7 This is the relationship curve between the optimal radius of a single-turn receiving coil and the transmission distance fitted by Matlab. The transmission distance is between 0.01m and 0.2m. 20 distance values ​​are taken. The linear cubic multi-form approximation fitting method is used to obtain the optimal radius r of the single-turn receiving coil. OR The expression of the system transmission distance H is:

[0052] R OR =-6.92H 3 +2.719H 2 +1.069H+0.01582

[0053] Among them, the sum and variance in the fitting is 8.662e-06, close to 0; the coefficient of determination is 0.9999, close to 1. This shows that the above formula realizes the optimal radius r of the single-turn receiving coil. OR The fitting effect is better between the relationship between the transmission distance H and the system.

[0054] In summary, each turn of the transmitting coil or receiving coil has an optimal radius under different transmission distances so that the system flux reaches the maximum value. Therefore, the present invention can improve the design of the conical spiral coil based on the expression of the optimal transmitting or receiving radius and the transmission distance, so that the radius of each turn of the transmitting or receiving coil can achieve the optimal value, and an optimized conical spiral coil can be designed, thereby maximizing the transmission performance of the system.

[0055] Step 5: Based on the quantitative relationship between the optimal transmitting or receiving radius and the transmission distance in the system of dual-planar circular coils, design the conical spiral coil transmitting coil and the conical spiral receiving coil in the system composed of the flat coil and the conical spiral coil.

[0056] The optimal radius value of each turn of the conical coil under the actual transmission distance (including the vertical turn spacing) is calculated so that all the turn radii of the conical spiral coil can obtain the optimal value, thereby designing an optimized conical spiral coil.

[0057] like Figure 8 To optimize the equivalent model of the conical spiral transmitting coil wireless power transmission system, the vertical turn spacing Δh of the spatial spiral transmitting coil is taken, and the distance H from the first turn of the transmitting coil to the circular receiving coil is 1 , calculate the optimal transmitting radius at this distance as the radius of the first transmitting coil, then the radius of the second transmitting coil is (H 1 +Δh) distance, ..., the radius of the nth turn of the transmitting coil is [H 1+(n-1)Δh], the optimal transmitting radius corresponding to the distance, the average value of the radius difference of each turn of the coil is calculated as the horizontal turn spacing of the spiral coil, thereby obtaining the optimized conical spiral transmitting coil;

[0058] like Fig. 9 To optimize the equivalent model of the conical spiral receiving coil wireless power transmission system, the vertical turn spacing Δh of the spatial spiral receiving coil is taken, and the distance H from the first turn of the receiving coil to the circular transmitting coil is 1 , calculate the optimal receiving radius at this distance as the radius of the first receiving coil, then the radius of the second receiving coil is (H 1 +Δh) distance, ..., the radius of the nth receiving coil is [H 1 +(n-1)Δh], the average value of the radius difference of each turn of the coil is calculated as the horizontal turn spacing of the spiral coil, thereby obtaining the optimized conical spiral receiving coil.

[0059] Example

[0060] In order to verify the effectiveness of the present invention, the following eddy current fields were constructed based on the finite element simulation software ANSYS platform: Fig. 9 The cylindrical spiral transmitting coil WPT system and the optimized conical spiral transmitting coil WPT system shown in the figure both use planar circular coils for receiving coils. The simulation parameter settings of the systems are shown in Table 1:

[0061] Table 1 System simulation parameters

[0062]

[0063] The optimized inter-turn radius difference ΔR of the conical spiral transmitting coil is: the average value of the inter-turn radius difference of the optimal radius of each turn of the transmitting coil under the corresponding transmission distance.

[0064] The resonant frequency of the system is set to 200kHz, and the mutual inductance values ​​of the two wireless power transmission systems are obtained through finite element simulation. The simulation results are shown in Table 2:

[0065] Table 2 System simulation results analysis

[0066]

[0067]

[0068] It can be seen that the optimized conical spiral transmitting coil WPT system has a higher mutual inductance value with less consumables and smaller volume. Compared with the cylindrical spiral transmitting coil WPT system, the conical transmitting coil has a 34.29% lower consumables and a 140.15% higher mutual inductance value, indicating that the optimized conical spiral transmitting coil wireless power transmission system proposed in the present invention has better transmission performance.

[0069] like Fig.11 The electromagnetic environment distribution of the cylindrical and optimized conical spiral transmitting coil WPT systems. Under the same input current condition, the optimized conical spiral transmitting coil has a better magnetic field concentration effect, the magnetic field of the system is more concentrated on the transmitting and receiving coils, and the leakage magnetic field in the surrounding environment is greatly reduced.

Claims

1. A method for designing a conical spiral coil in a wireless power transmission system, characterized in that: The coil design method is applicable to a wireless power transmission system including a planar circular coil and a conical spiral coil. The specific design process is as follows: Step 1: Modeling and calculating a wireless power transmission system including a planar circular transmitting coil and a planar circular receiving coil to determine a magnetic flux function of the system of the double planar circular coils; Step 2: When the number of turns and the turn spacing of the transmitting coil, the inner diameter, the number of turns, the turn spacing of the receiving coil and the transmission distance are determined, the relationship between the magnetic flux and the radius of the transmitting coil and the relationship between the magnetic flux and the radius of the receiving coil are analyzed; Step 3: Under different transmission distances, establish and analyze the relationship between the optimal transmission radius of the transmitting coil and the optimal receiving radius of the receiving coil as the transmission distance increases; Step 4, quantifying the relationship between the optimal radius of a single-turn transmitting coil and the transmission distance, and quantifying the relationship between the optimal radius of a single-turn receiving coil and the transmission distance; Step 5: Based on the quantitative relationship between the optimal transmitting or receiving radius and the transmission distance in the system of the dual-planar circular coil, design the conical spiral coil transmitting coil and the conical spiral receiving coil in the flat coil-conical spiral coil system.

2. The design method of a conical spiral coil in a wireless power transmission system according to claim 1, characterized in that: In step 1, the magnetic flux expression of the wireless power transmission system composed of a planar circular transceiver coil is: In formula (1), Ψ is the flux through the curved receiving coil, j is the jth turn of the receiving coil from the inside, Φ sj is the connection formula (1), Ψ is the magnetic flux of the system, n1 is the number of turns of the transmitting coil, n2 is the number of turns of the receiving coil, d1 is the turn spacing of the transmitting coil, d2 is the turn spacing of the receiving coil, R1 is the outer radius of the transmitting coil, r2 is the inner radius of the receiving coil, R(i) is the radius of the i-th (i=1,2,...,n1)-th turn of the transmitting coil, R(j) is the radius of the j-th (j=1,2,...,n2)-th turn of the receiving coil, μ0 is the vacuum permeability, I is the current flowing through the transmitting coil, H is the transmission distance of the system, and r is the integral variable. E(k) and K(k) are the first and second kind complete elliptic integrals, respectively.

3. The design method of a conical spiral coil in a wireless power transmission system according to claim 1, characterized in that: In step 2, after analysis, the transmitting coil radius value that can make the system magnetic flux obtain the maximum value is defined as the optimal transmitting radius, and the receiving coil radius value that can make the system magnetic flux obtain the maximum value is defined as the optimal receiving radius.

4. The design method of a conical spiral coil in a wireless power transmission system according to claim 3, characterized in that: In step 3, the transmission distance of the system is divided into equal intervals, a distance characteristic value is taken from each equal interval, the optimal radius corresponding to each distance characteristic value is calculated, and then the curve is fitted to explore the change of the optimal transmitting radius of the transmitting coil as the transmission distance increases; explore the change of the optimal receiving radius of the receiving coil as the transmission distance increases.

5. The design method of a conical spiral coil in a wireless power transmission system according to claim 4, characterized in that: In step 3, after analysis, we get: As the transmission distance increases, the optimal transmission radius also increases; as the transmission distance increases, the maximum value of the magnetic flux drops rapidly; As the transmission distance increases, the optimal receiving radius also increases, and as the transmission distance increases, the maximum value of the magnetic flux drops rapidly.

6. The design method of a conical spiral coil in a wireless power transmission system according to claim 1, characterized in that: In step 4, the relationship between the optimal radius of the quantified single-turn transmitting coil and the transmission distance is obtained by Matlab fitting, and the relationship between the optimal radius of the quantified single-turn receiving coil and the transmission distance is obtained.

7. The method for designing a conical spiral coil in a wireless power transmission system according to claim 1, characterized in that: In step 5, the specific method for optimizing the conical spiral transmitting coil is: Take the vertical turn spacing Δh of the spatial spiral transmitting coil and the distance H1 from the first turn of the conical spiral transmitting coil to the circular receiving coil, calculate the optimal transmitting radius at this distance as the radius of the first turn of the conical spiral transmitting coil, then the radius of the second turn of the conical spiral transmitting coil is the optimal transmitting radius corresponding to the distance (H1+Δh), and so on, the radius of the nth turn of the conical spiral transmitting coil is the optimal transmitting radius corresponding to the distance [H1+(n-1)Δh], calculate the average value of the radius difference of each turn of the coil as the horizontal turn spacing of the spiral coil, and thus the optimized conical spiral transmitting coil can be obtained.

8. The method for designing a conical spiral coil in a wireless power transmission system according to claim 1, characterized in that: In step 5, the specific method for optimizing the conical spiral receiving coil is: Take the vertical turn spacing Δh of the spatial spiral receiving coil, the distance H1 from the first turn of the conical spiral receiving coil to the circular transmitting coil, calculate the optimal receiving radius at this distance as the radius of the first turn of the conical spiral receiving coil, then the radius of the second turn of the conical spiral receiving coil is the optimal receiving radius corresponding to the distance (H1+Δh), and so on. The radius of the nth turn of the conical spiral receiving coil is the optimal receiving radius corresponding to the distance [H1+(n-1)Δh]. Calculate the average value of the radius difference of each turn of the coil as the horizontal turn spacing of the spiral coil, thereby obtaining the optimized conical spiral receiving coil.

9. A wireless power transmission system, characterized in that: A conical spiral coil designed by the design method of a conical spiral coil according to any one of claims 1 to 8, and a flat circular coil.

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