Design method of wireless power transmission coupling coil

Abstract

The invention discloses a design method and device of a wireless electric energy transmission coupling coil and electronic equipment. The method comprises the following steps: determining an optimization target of a coupling coil mechanism; determining an optimization objective function of the rounded rectangular coupling coil according to the optimization objective of the coupling coil mechanism, taking the geometric constraint of the rounded rectangular coupling coil as a design constraint, and optimizing decision variables in the optimization objective function by adopting a multi-objective genetic algorithm to obtain a geometric parameter optimal solution set of the rounded rectangular coupling coil; and evaluating the geometric parameter optimal solution set by using an entropy weight Topsis decision algorithm to obtain the optimal geometric parameter of the rounded rectangular coupling coil, the wireless power transmission coupling coil is designed according to the optimal geometric parameter, the precision design of the coupling coil is realized on the premise that the wireless power transmission system meets the design requirement, and the design efficiency of the coupling coil is improved. The efficiency of the wireless power transmission system is improved.

Description

Technical Field

[0001] This application relates to the technical field of wireless power transmission, and particularly to a design method, device, and electronic device for a wireless power transmission coupling coil. Background Art

[0002] Wireless power transmission technology can transfer electrical energy from a transmitter to a receiver without electrical connection, and it is a technology that uses the characteristics of electromagnetic fields for energy transmission. Among them, magnetic coupling resonance wireless power transmission technology has high power and efficiency, and is widely used in fields such as electric vehicles, drones, and biomedical devices. Magnetic coupling resonance wireless power transmission technology achieves efficient wireless power transmission by tuning the transmitting circuit and the receiving circuit to the same driving frequency and establishing an energy transmission channel through the resonant state. Among them, the coupling mechanism (i.e., the transmitting coil and the receiving coil) is the medium for power transmission and plays a crucial role in the efficient and stable transmission of electrical energy. By establishing a circuit model to analyze the transmission performance of a magnetic coupling resonance wireless power transmission system, it can be seen that the performance parameters of the coupling mechanism will directly affect the received power and transmission efficiency of the wireless power transmission system. Therefore, in order to improve the received power and transmission efficiency of the WPT system, the design and performance optimization of the coupling coil are the key issues that must be solved first.

[0003] Regarding the design optimization method of the coupling mechanism for a magnetic coupling resonance wireless power transmission system, through literature induction and summary, the existing research mainly focuses on:

[0004] (1) Optimization design of the coupling coil shape. The shape of the coupling coil is an important factor affecting the coupling performance. Coils with the same material but different shapes have very different parameters and performance; therefore, designing special-shaped coils to improve the coupling performance is the most widely adopted design scheme.

[0005] (2) Optimization design of the geometric parameters of the coupling coil. For the geometric parameters of a single coupling coil with a fixed shape, such as wire diameter, number of turns, turn spacing, inner and outer diameters, etc., optimization design is carried out. First, the optimization objectives are obtained through theoretical analysis, and then multi-parameter optimization methods are used to solve the optimal design parameters.

[0006] In industrial design: A large number of coil design cases adopt method (1) to optimize the coil shape. Currently, there are various special-shaped coupling coils with excellent performance, such as array coils, three-phase coils, and bowl-shaped coils. However, these special-shaped coils generally have problems of large wire consumption and heavy weight, and are not suitable for application scenarios with high requirements for weight and space, such as smart wearable electronic devices and drones. Through research, it is found that the geometric parameters of the coupling coil also affect the performance of the coil. Therefore, in recent years, some design cases have switched to method (2), using a multi-objective optimization method to iteratively design the optimal geometric parameters of the rounded rectangle coupling coil. This method can adjust the optimization objective according to the design focus and design a coupling coil with high performance. However, a large number of design cases only consider the performance of a single coil itself, mainly focusing on the quality factor of the coil. In a magnetic coupling resonant wireless power transmission system, the coupling coefficient is the most critical parameter for judging the coupling performance of the coil. Therefore, for the optimization design of the coil, it is necessary to consider the influence of the entire coupling mechanism while analyzing a single coil. At the same time, since some design cases optimize the wire diameter of the coil, this coupling coil with variable wire diameter design is not suitable for being wound with Litz wire and can only be made of PCB. This rigid coil shape is not flexible and does not have wide adaptability. Summary of the Invention

[0007] The main purpose of this application is to provide a design method, device, and electronic device for a wireless power transmission coupling coil, aiming to precisely design the coupling coil on the premise of meeting the design requirements of the wireless power transmission system, improve the efficiency of the wireless power transmission system, and reduce technical problems such as the volume and weight of the system.

[0008] To achieve the above object, the present application provides a design method for a wireless power transfer coupling coil, including: determining an optimization objective for the coupling coil mechanism based on the structure of the series-series resonance compensation topology of a magnetic coupling resonance type wireless power transfer system, where the optimization objective is to determine a coupling coil mechanism with the smallest internal resistance and the largest coupling coefficient within the design constraints. The coupling coil mechanism includes a transmitting coil and a receiving coil, and both the transmitting coil and the receiving coil are wound with Litz wire; determining a rounded rectangle coupling coil model according to the constraint relationship between the geometric parameters of the rounded rectangle coupling coil, and constructing an expression for the coupling coefficient and an expression for the sum of the internal resistances of the receiving coil and the transmitting coil of the rounded rectangle coupling coil according to the rounded rectangle coupling coil model. According to the optimization objective of the coupling coil mechanism, determining an optimization objective function for the rounded rectangle coupling coil, taking the geometric parameter constraints of the rounded rectangle coupling coil as design constraints, and obtaining a parameter optimization problem to be solved based on the optimization objective function and the geometric parameter constraints; randomly selecting an initial value of the geometric parameter to generate an initial population, and solving the parameter optimization problem using a multi-objective genetic algorithm based on the initial population to obtain an optimal solution set of the geometric parameters of the rounded rectangle coupling coil; using an entropy weight Topsis decision algorithm to evaluate the optimal solution set of the geometric parameters to obtain the optimal geometric parameters of the rounded rectangle coupling coil, and designing a wireless power transfer coupling coil according to the optimal geometric parameters.

[0009] Optionally, determining the optimization objective for the coupling coil mechanism based on the topology of the series-series resonance compensation of the magnetic coupling resonance type wireless power transfer system includes: performing circuit analysis on the topology of the series-series resonance compensation to obtain an expression for the transmission efficiency of the system, where the expression for the transmission efficiency of the system is:

[0010]

[0011] In the formula, ω represents the angular frequency of the system; R L represents the load impedance; L T respectively represent the equivalent self-inductance of the transmitting coil, R T represents the internal resistance of the transmitting end coupling coil; L R represents the equivalent self-inductance of the receiving coil; R R represents the internal resistance of the receiving coil; k represents the coupling coefficient between the transmitting coil and the receiving coil, and η represents the transmission efficiency; based on the fixed load R L and the working angular frequency w, obtaining the key parameters affecting the transmission efficiency, where the key parameters are the internal resistances of the transmitting coil and the receiving coil, and the coupling coefficient between the transmitting coil and the receiving coil; determining the optimization objective for the coupling coil mechanism based on the internal resistances of the transmitting coil and the receiving coil and the coupling coefficient between the transmitting coil and the receiving coil.

[0012] Optionally, the expression for the constraint relationship between the geometric parameters of the rounded rectangle coupling coil is:

[0013]

[0014] Among them, a is the inner diameter of the arc, representing the distance from the center point of the transmitting coil / receiving coil to the four arcs, y is the half side length, representing the distance from the center point of the transmitting coil / receiving coil to the square side, and x is the half inner side length, representing the length of the square side of the transmitting coil / receiving coil excluding the arcs.

[0015] Optionally, the geometric parameters of the rounded rectangular coupling coil include: coil turn number parameter, coil half inner side length parameter, coil half side length parameter, and coil arc radius parameter.

[0016] Optionally, the expression of the objective function includes maximizing the coupling coefficient of the rounded rectangular coupling coil; the determination process of the expression of the coupling coefficient includes: constructing the mutual inductance expression of two coaxial single-turn transmitting coils and a single-turn receiving coil according to the Neumann formula; constructing the mutual inductance expression of the rounded rectangular coupling coil based on the sum expression of the mutual inductances between all coaxial single-turn coils; constructing the self-inductance expression of each turn of the transmitting coil / receiving coil of the rounded rectangular coupling coil according to a preset empirical formula; determining the equivalent self-inductance expression of the transmitting coil / receiving coil respectively based on the sum of the self-inductances and mutual inductances of each turn inside the transmitting coil / receiving coil; obtaining the coupling coefficient expression of the rounded rectangular coupling coil according to the conversion relationship between the coupling coefficient expression of the coil, the mutual inductance expression of the coil, and the self-inductance expression of the coil.

[0017] Optionally, the expression of the objective function further includes minimizing the sum of the internal resistances of the rounded rectangular coupling coil; the determination process of the expression of the sum of the internal resistances includes: determining the expression of the sum of the internal resistances of the rounded rectangular coupling coil based on a preset total winding length expression and an estimated expression of the coil AC internal resistance.

[0018] Optionally, randomly selecting the initial values of the geometric parameters to generate an initial population, and using a multi-objective genetic algorithm to solve the parameter optimization problem based on the initial population to obtain the optimal solution set of the geometric parameters of the rounded rectangular coupling coil, including: performing a mutation operation on the geometric parameters in the parental population with a first preset probability and a crossover recombination operation with a second preset probability to generate a geometric parameter sequence as the offspring population; combining the parental population and the offspring population to form a new population, calculating the function values corresponding to the offspring population according to the optimization objective function, performing fast non-dominated sorting and crowding degree sorting on the new population according to the function values, and selecting the geometric parameter sequences of the currently optimal preset number of coupling coils as the new parental population; iteratively calculating the above steps until the iteration termination condition is reached to obtain the optimal solution set of the geometric parameters of the rounded rectangular coupling coil.

[0019] Optionally, the entropy weight TOPSIS decision algorithm is used to evaluate the optimal solution set of geometric parameters to obtain the optimal geometric parameters of the rounded rectangle coupled coil, including: constructing an original evaluation matrix according to the optimal solution set of the geometric parameters of the coupled coil and the evaluation index of the sum of the coupling coefficient and the internal resistance of each optimal solution in the optimal solution set of geometric parameters; using the element calculation formula of the preset decision matrix to process each element of the original evaluation matrix, determining each element of the decision matrix, and constructing a decision matrix based on each element of the decision matrix; obtaining the characteristic proportion of each element based on the ratio of each element of the decision matrix to the sum of the elements in its corresponding row; calculating the information entropy of each evaluation index based on the characteristic proportion of each element; calculating the weight of each evaluation index based on each information entropy; performing weighted processing on each element in the decision matrix using the weight of the evaluation index to obtain a comprehensive evaluation matrix; obtaining the positive and negative ideal solutions of the evaluation indexes of the coupling coefficient and the coil internal resistance; respectively calculating the distance between the comprehensive evaluation matrix and the positive ideal solution and the distance between the negative ideal solution; calculating the closeness corresponding to all optimal solutions according to the distance between the positive ideal solution and the distance between the negative ideal solution, and taking the geometric parameters corresponding to the optimal solution closest to 1 as the optimal geometric parameters of the rounded rectangle coupled coil.

[0020] To achieve the above object, the present application further provides a design device for a wireless power transmission coupled coil, including: a topology analysis module, configured to determine an optimization target of the coupled coil mechanism based on the structure of the series-series resonance compensation topology of the magnetic coupling resonance type wireless power transmission system, where the optimization target is to determine a coupled coil mechanism with the smallest internal resistance and the largest coupling coefficient within the design constraints, where the coupled coil mechanism includes a transmitting coil and a receiving coil, and both the transmitting coil and the receiving coil are wound by Litz wire; an expression construction module, configured to determine a rounded rectangle coupled coil model according to the constraint relationship between the geometric parameters of the rounded rectangle coupled coil, and construct an expression of the coupling coefficient and an expression of the sum of the internal resistances of the receiving coil and the transmitting coil of the rounded rectangle coupled coil according to the rounded rectangle coupled coil model, determine an optimization objective function of the rounded rectangle coupled coil according to the optimization target of the coupled coil mechanism, use the geometric parameter constraints of the rounded rectangle coupled coil as design constraints, and obtain a parameter optimization problem to be solved based on the optimization objective function and the geometric parameter constraints; a solution set solving module, configured to randomly select an initial value of geometric parameters to generate an initial population, and solve the parameter optimization problem using a multi-objective genetic algorithm based on the initial population to obtain an optimal solution set of the geometric parameters of the rounded rectangle coupled coil; an optimal parameter determination module, which uses the entropy weight TOPSIS decision algorithm to evaluate the optimal solution set of geometric parameters to obtain the optimal geometric parameters of the rounded rectangle coupled coil, and designs a wireless power transmission coupled coil according to the optimal geometric parameters.

[0021] To achieve the above object, the present application further provides an electronic device, which includes: at least one processor, a memory, and an input / output unit; wherein, the memory is used to store a computer program, and the processor is used to call the computer program stored in the memory to execute the design method of the wireless power transfer coupling coil provided in any of the foregoing embodiments.

[0022] A design method, device, and electronic device for a wireless power transfer coupling coil proposed in an embodiment of the present application determine an optimization target for the coupling coil mechanism based on the structure of the series-series resonance compensation topology of a magnetic coupling resonance type wireless power transfer system. The optimization target is to determine a coupling coil mechanism with the minimum internal resistance and the maximum coupling coefficient within the design constraints. Among them, the coupling coil mechanism includes a transmitting coil and a receiving coil, and both the transmitting coil and the receiving coil are wound with Litz wire; according to the constraint relationship between the geometric parameters of the rounded rectangular coupling coil, a rounded rectangular coupling coil model is determined, and based on the rounded rectangular coupling coil model, an expression for the coupling coefficient and an expression for the sum of internal resistances of the receiving coil and the transmitting coil of the rounded rectangular coupling coil are constructed. According to the optimization target of the coupling coil mechanism, an optimization objective function for the rounded rectangular coupling coil is determined. Taking the geometric parameter constraints of the rounded rectangular coupling coil as design constraints, a parameter optimization problem to be solved is obtained based on the optimization objective function and the geometric parameter constraints; randomly select an initial value of the geometric parameters to generate an initial population, and use a multi-objective genetic algorithm to solve the parameter optimization problem based on the initial population to obtain an optimal solution set of the geometric parameters of the rounded rectangular coupling coil; use the entropy weight Topsis decision algorithm to evaluate the optimal solution set of the geometric parameters to obtain the optimal geometric parameters of the rounded rectangular coupling coil, and design the wireless power transfer coupling coil according to the optimal geometric parameters. On the premise of meeting the design requirements of the wireless power transfer system, the coupling coil can be precisely designed, the efficiency of the wireless power transfer system can be improved, the volume and weight of the system can be reduced. At the same time, the present application can also provide a reference for the design of the coupling coil and has good engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic flowchart provided by an embodiment of the design method of the wireless power transfer coupling coil of the present application;

[0024] Figure 2 It is a series-series type resonance compensation topology structure diagram provided by an embodiment of the design method of the wireless power transfer coupling coil of the present application;

[0025] Figure 3 It is a parameter schematic diagram of the coupling coil provided by an embodiment of the design method of the wireless power transfer coupling coil of the present application;

[0026] Figure 4It is a mutual inductance calculation model of coil m and coil n provided by an embodiment of the design method of the wireless power transfer coupling coil of the present application;

[0027] Figure 5 It is a self-inductance calculation model of coil m and coil n provided by an embodiment of the design method of the wireless power transfer coupling coil of the present application;

[0028] Figure 6 It is the optimization result of the geometric parameters of the coupling coil provided by an embodiment of the design method of the wireless power transfer coupling coil of the present application;

[0029] Figure 7 It is the structural block diagram provided by an embodiment of the design device of the wireless power transfer coupling coil of the present application.

[0030] The realization of the purpose, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. Specific embodiments

[0031] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0032] Glossary: Litz wire is composed of multiple strands of fine copper wires twisted together. The diameter of each copper wire is usually between 0.05 - 0.2 mm, and the surface is coated with an insulating paint film to ensure insulation from each other. This structure enables the current to be evenly distributed among the wires, reducing high-frequency losses.

[0033] Aiming at the problems of the prior art, the present invention proposes a design and optimization method for a coupling mechanism for a wireless power transfer system that can use Litz wire winding. This method remodels the planar coil, and the proposed model can cover most types of planar coils by adjusting geometric parameters; uses the NSGA-II multi-objective optimization method to calculate the solution set of the optimal geometric parameters of the coil, considering the coupling coefficient and the internal resistance of the coupling coil, and simultaneously optimizing the receiving coil and the transmitting coil; finally uses the entropy weight Topsis decision-making method to evaluate the optimal solution set of geometric parameters and find a suitable optimal solution. This method models the geometric structure of the coupling coil in detail and can be used in precision design occasions, and finely optimizes the coupling mechanism according to the design focus; at the same time, the present invention can provide a reference for the design of the coupling coil, can further improve the performance of the magnetic coupling resonance wireless power transfer system, and has high application value.

[0034] Referring to Figure 1 , the first embodiment of the present application provides a design method for a wireless power transfer coupling coil. The design method for the wireless power transfer coupling coil may include:

[0035] S10. Determine the optimization objective of the coupling coil mechanism based on the structure of the series - series resonance compensation topology of the magnetic - coupled resonant wireless power transfer system. The optimization objective is to determine the coupling coil mechanism with the minimum internal resistance and the maximum coupling coefficient within the constraints. Here, the coupling coil mechanism includes a transmitting coil and a receiving coil, and both the transmitting coil and the receiving coil are wound with Litz wire.

[0036] In an embodiment of the present application, step S10 may include the following execution process:

[0037] S101. Conduct circuit analysis on the series - series resonance compensation topology to obtain the expression of the transmission efficiency of the system. Among them, the expression of the transmission efficiency of the system is:

[0038]

[0039] In the formula, ω represents the angular frequency of the system; R L represents the load impedance; L T respectively represent the equivalent self - inductance of the transmitting coil, R T represents the internal resistance of the transmitting - end coupling coil; L R represents the equivalent self - inductance of the receiving coil; R R represents the internal resistance of the receiving coil; k represents the coupling coefficient between the transmitting coil and the receiving coil, and η represents the transmission efficiency.

[0040] It can be seen from the formula that once the load R L and the working angular frequency ω of the system are determined, the internal resistances R T and R R of the coupling coils, and their coupling coefficient k become the only parameters affecting the transmission efficiency of the magnetic - coupled resonant wireless power transfer system. Specifically, the larger the coupling coefficient of the coupling coil, the smaller the internal resistance value of the coil, and the higher the transmission efficiency of the system. Therefore, the problem of optimizing the working efficiency of the magnetic - coupled resonant wireless power transfer system is transformed into the problem of searching for the coupling mechanism with the minimum internal resistance and the maximum coupling coefficient within the constraints.

[0041] S102. Based on the fixed load R L and the working angular frequency ω, obtain the key parameters affecting the transmission efficiency. The key parameters are the internal resistances of the transmitting coil and the receiving coil, and the coupling coefficient between the transmitting coil and the receiving coil.

[0042] S103. Determine the optimization objective of the coupling coil mechanism based on the internal resistances of the transmitting coil and the receiving coil and the coupling coefficient between the transmitting coil and the receiving coil.

[0043] S20. Determine the rounded rectangular coupling coil model according to the constraint relationship between the geometric parameters of the rounded rectangular coupling coil, and construct the coupling coefficient expression and internal resistance sum expression of the receiving coil and the transmitting coil of the rounded rectangular coupling coil according to the rounded rectangular coupling coil model. Determine the optimization objective function of the rounded rectangular coupling coil according to the optimization objective of the coupling coil mechanism. Take the geometric parameter constraints of the rounded rectangular coupling coil as design constraints, and obtain the parameter optimization problem to be solved based on the optimization objective function and geometric parameter constraints.

[0044] Among them, the expression of the constraint relationship between the geometric parameters of the rounded rectangular coupling coil is:

[0045]

[0046] In the formula, a is the inner arc diameter, representing the distance from the center point of the transmitting coil / receiving coil to the four arcs; y is the half side length, representing the distance from the center point of the transmitting coil / receiving coil to the square side; x is the half inner side length, representing the length of the square side of the transmitting coil / receiving coil excluding the arcs.

[0047] Appendix Figure 3 is the schematic structural diagram of the rounded rectangular coupling coil proposed by the present invention. This structure is between the traditional circular and square planar coils, and the geometric parameters of the coil are marked in Appendix Figure 3 : Among them, the number of turns of the coil is defined as n, the turn spacing between every two turns is defined as z, the distance from the center point to the four arcs is defined as the inner arc diameter a, θ is the central angle of the arc, the length of the square side excluding the arcs is defined as the half inner side length x, and the distance from the center point to the square side is defined as the half side length y. The subscript n represents a certain turn of the coupling coil. For a certain determined turn, there is the above-mentioned constraint relationship among the inner arc diameter a, the inner side length x, and the half side length y of the rounded square coupling coil.

[0048] According to the geometric parameters given in Appendix Figure 3 , it can be seen that the rounded rectangular coupling coil proposed by the present invention can be changed into a common planar coupling coil by adjusting parameters, specifically as follows:

[0049] When a n = 0, that is, there is no arc at the edge of the coil, and the coil is a planar rectangular coil;

[0050] When a n = y n , that is, x n = 0, the coil is a planar circular coil at this time;

[0051] In other cases, the coil is a rounded rectangular coil.

[0052] Therefore, the rounded-corner coil proposed by the present invention can simulate various coil structures and has a higher degree of freedom for the coil structure during optimization.

[0053] In an embodiment of the present application, the geometric parameters of the rounded-corner rectangular coupling coil include: the coil turn number parameter, the inner half-side length parameter of the coil, the half-side length parameter of the coil, and the arc radius parameter of the coil. The geometric parameters of the coil will be used as decision variables for the optimization objective.

[0054] It should be noted that there is the following conversion relationship between the coupling coefficient of the coil and the mutual inductance and self-inductance Therefore, to derive the expression of the coupling coefficient, it is necessary to separately derive the mutual inductance between the two coupling coils and their respective self-inductances. The calculation method of the mutual inductance between coils is as follows: the entire coil is split into many single-turn coils, and then the mutual inductance values of each single-turn coil are summed to obtain the mutual inductance value between the coils. The schematic diagram of the mutual inductance model between the m-th turn coil (denoted as coil m) from the outside to the inside of the transmitting coil and the n-th turn coil (denoted as coil n) from the outside to the inside of the receiving coil is shown in the appendix Figure 4 as shown. Among them, the radii of the four rounded corners of the transmitting coil and the receiving coil are a m and a n respectively; the length micro-elements in coil m and coil n are denoted as dl m and dl n respectively; γ and δ are the angles between the micro-element dl m and the micro-element dl n and the x-axis respectively; h is the vertical distance between coil m and coil n, that is, the wireless power transmission distance; h mn represents the distance between the micro-element dl m and the micro-element dl n respectively.

[0055] In an embodiment of the present application, the expression of the objective function includes maximizing the coupling coefficient of the rounded-corner rectangular coupling coil; the determination process of the expression of the coupling coefficient includes:

[0056] S201. Construct the mutual inductance expression of two coaxial single-turn transmitting coils and a single-turn receiving coil according to Neumann's formula;

[0057] Specifically, according to Neumann's formula, the mutual inductance M mn between two coaxial single-turn coils can be expressed as:

[0058]

[0059] where μ0 is the magnetic permeability of vacuum or air, with a value of 4π×10 -7 H / m. The calculation methods of the parameters in the formula are shown in formulas (4)-(5):

[0060]

[0061] Among them, and respectively represent the direction vectors of coil m and coil n, and dγ is the differential element dl m and the differential element dl n and the differential angle between the differential element dl

[0062] Let p1 and p2 be the turn spacings of the transmitting coil and the receiving coil respectively, r f and r j are the outer radii of the transmitting coil and the receiving coil respectively, and d represents the outer diameter of the Litz wire used to wind the coil. Then the arc radii of the two single-turn coils can be respectively expressed as:

[0063]

[0064] According to the above method, the mutual inductance of a single-turn coaxial planar coil can be calculated. The total mutual inductance M between two coaxial planar coils can be regarded as the sum of the mutual inductances of each single-turn coil inside the two coils.

[0065] S202. Construct the mutual inductance expression of the rounded rectangular coupling coil based on the expression of the sum of the mutual inductances between all coaxial single-turn coils.

[0066] According to the above method, it can be calculated that the mutual inductance M between two coaxial planar coils with the total number of turns N1 and N2 can be regarded as the sum of the mutual inductances of each single-turn coil inside the two coils:

[0067]

[0068] S203. Construct the self-inductance expressions of each turn of the transmitting coil / receiving coil of the rounded rectangular coupling coil according to the preset empirical formula;

[0069] The calculation model of the self-inductance of a single coil is as shown in Appendix Figure 5 . Among them, the differential elements of the i-th turn and the j-th turn of the two coils are respectively denoted as dl i and dl j , δ and β are respectively the angles between the differential element dl i and the differential element dl j and the x-axis, and h ij represents the distance between the differential element dl i and the differential element dl j . The self-inductance L(i) of a single-turn coil can be obtained from the following empirical formula:

[0070]

[0071] Among them, μ0 is the magnetic permeability of vacuum or air, a iis the arc radius of the single-turn coil, d is the outer diameter of the Litz wire used to wind the coil, and i and j respectively represent any two turns inside the coil with a total number of turns N. The self-inductance of the coil can be approximately regarded as the sum of the self-inductance of each turn inside it and the mutual inductance between any two turns inside it, that is:

[0072]

[0073] S204. Determine the equivalent self-inductance expressions of the transmitting coil and the receiving coil respectively based on the sum of the self-inductance and mutual inductance of each turn inside the transmitting coil / receiving coil;

[0074] S205. Obtain the coupling coefficient expression of the rounded rectangle coupling coil according to the conversion relationship between the coupling coefficient expression of the coil, the mutual inductance expression of the coil, and the self-inductance expression of the coil.

[0075] That is to say, according to the derived mutual inductance expression and self-inductance expression, using the conversion relationship between the coupling coefficient and the mutual inductance and self-inductance the expression of the coupling coefficient can be obtained.

[0076] In an embodiment of the present application, the expression of the objective function further includes that the internal resistance sum of the rounded rectangle coupling coil is the smallest; the determination process of the internal resistance sum expression includes:

[0077] S206. Determine the expression of the internal resistance sum of the rounded rectangle coupling coil based on the preset total winding length expression and the coil AC internal resistance estimation expression.

[0078] Specifically, the internal resistance of the coupling coil is the reason for the heat loss generated by the coil during operation, so the internal resistance is related to the efficiency of the system's electrical energy transmission. Reducing the internal resistance of the coil can effectively reduce the heat loss. The estimation expression of the coil AC internal resistance is:

[0079]

[0080] where K C [[ID=�1]]is the stranding coefficient, generally taking a value of 1.03; ρ is the conductivity, and its value is 1.72×10 -8 S / m; N a is the number of strands; d s is the wire diameter of a single strand; f is the working frequency of the system; l is the total winding length of the coil. According to the geometric parameters of the rounded rectangle coupling coil given in the appendix Figure 3 the method for calculating the total winding length of the coil is as follows:

[0081]

[0082] S30. Randomly select the initial values of geometric parameters to generate an initial population, and use the multi-objective genetic algorithm to solve the parameter optimization problem based on the initial population, so as to obtain the optimal solution set of the geometric parameters of the rounded rectangle coupled coil.

[0083] In an embodiment of the present application, step S30 may include the following execution process:

[0084] S301. Mutate the geometric parameters in the parental population with a first preset probability and perform crossover recombination with a second preset probability to generate a geometric parameter sequence as the offspring population.

[0085] S302. Combine the parental population and the offspring population to form a new population, calculate the function values corresponding to the offspring population according to the optimization objective function, perform fast non-dominated sorting and crowding degree sorting on the new population according to the function values, and select the current optimal geometric parameter sequence as the new parental population.

[0086] S303. Iteratively calculate the above steps until the iteration termination condition is reached, and obtain the optimal solution set of the geometric parameters of the rounded rectangle coupled coil.

[0087] In the specific implementation process, perform multi-objective optimization to obtain the optimal solution set {X1, X2, X3, …, X m} of the coupled coil mechanism. The specific implementation steps are as follows:

[0088] Step1: Set the objective functions according to formulas (3)-(10). F1 represents 1 minus the coupling coefficient between the two coils, and F2 represents the sum of the internal resistances of the two coils.

[0089]

[0090] Step2: Set the constraint conditions of the geometric parameters of the coupled coil according to the design requirements of the wireless power transmission system.

[0091] Step3: Set the population size M, the maximum number of iterations G max of the multi-objective genetic algorithm, the mutation probability cp, and the crossover recombination probability mp. Randomly select the initial values of the geometric parameters of the coupled coil within the constraints to generate an initial population as the parental population, and let the iteration number identifier G = 1.

[0092] Step4: For the geometric parameter sequence of the coupled coil in the parental population, perform mutation operation with a first preset probability cp and perform crossover recombination operation with a second preset probability mp to generate a new geometric parameter sequence of the coupled coil as the offspring population.

[0093] Step 5: Combine the parental population and the offspring population to form a new population. Calculate the corresponding objective functions F1 and F2 under the given geometric parameters of the coupling coil according to Equation (11). Perform fast non-dominated sorting and crowding degree sorting on the combined population based on the values of F1 and F2, and select the current optimal q geometric parameter sequences of the coupling coil as the new parental population;

[0094] Step 6: Determine whether the algorithm iteration termination condition is satisfied, that is, determine whether the iteration number G reaches the upper limit G max , if the termination condition is reached, execute Step 7; otherwise, jump to Step 4 and update the iteration number identifier G = G + 1;

[0095] Step 7: Obtain the optimal solution set of the geometric parameters of the coupling coil {X1, X2, X3, …, X m} from the above operations to complete the multi-objective optimization solution of the coupling coil.

[0096] S40. Use the entropy weight Topsis decision algorithm to evaluate the optimal solution set of geometric parameters, obtain the optimal geometric parameters of the rounded rectangle coupling coil, and design the wireless power transfer coupling coil according to the optimal geometric parameters.

[0097] In an embodiment of the present application, step S40 may include the following execution process:

[0098] S401. Construct an original evaluation matrix according to the optimal solution set of the geometric parameters of the coupling coil and the evaluation index of the sum of the coupling coefficient and the internal resistance in each optimal solution in the optimal solution set of the geometric parameters;

[0099] S402. Process each element of the original evaluation matrix using the preset element calculation formula of the decision matrix to determine each element of the decision matrix, and construct a decision matrix based on each element of the decision matrix;

[0100] S403. Obtain the characteristic proportion of each element based on the ratio of each element of the decision matrix to the sum of the elements in its corresponding row;

[0101] S404. Calculate the information entropy of each evaluation index based on the characteristic proportion of each element;

[0102] S405. Calculate the weight of the evaluation index based on the information entropy;

[0103] S406. Perform weighted processing on each element in the decision matrix using the weight of the evaluation index to obtain a comprehensive evaluation matrix;

[0104] S407. Obtain the positive and negative ideal solutions of the evaluation indexes of the coupling coefficient and the coil internal resistance;

[0105] S408. Calculate the distances between the comprehensive evaluation matrix and the positive ideal solution and the negative ideal solution respectively;

[0106] S409. Calculate the closeness degree corresponding to all optimal solutions according to the distances from the positive ideal solution and the negative ideal solution, and use the geometric parameters corresponding to the optimal solutions with a closeness degree close to 1 as the optimal geometric parameters of the rounded rectangular coupled coil.

[0107] In the specific execution process, the execution process of the above steps can be as follows:

[0108] Step1: According to the optimal solution set of the geometric parameters of the coupled coil {X1, X2, X3, …, X m}, and the evaluation indexes {I1, I2} of the coupling coefficient and the internal resistance of the coil for each optimal solution, construct the original evaluation matrix R = [r ij m×2 , r ij is the value of the jth index of the ith optimal solution in the optimal solution set, where 1 ≤ i ≤ m and 1 ≤ j ≤ 2.

[0109] Step2: Convert R = [r ij m×2 into the decision matrix A = [a ij m×2 , and the calculation of a ij in the decision matrix A is as follows:

[0110]

[0111] Step3: Calculate the characteristic weight p ij :

[0112]

[0113] Step4: Calculate the entropy value e j :

[0114]

[0115] Step5: Determine the weight ω j :

[0116]

[0117] Step6: Perform weighted processing on each element in the decision matrix A = [a ij m×2 : z ij = a ij ω j , and obtain the comprehensive evaluation matrix as:

[0118] Z = [z ij m×2 (15)

[0119] ​​​​​Step7: Determine the evaluation index I of the coupling coefficient and the internal resistance of the coil j Positive and negative ideal solutions of:

[0120] Positive ideal solution: Where

[0121] Negative ideal solution: Where

[0122] Step8: Calculate the distances between the optimal solution set of the geometric parameters of the coupled coil and the positive and negative ideal solutions:

[0123] Distance from the positive ideal solution Distance from the negative ideal solution

[0124] Step9: Calculate the closeness degrees corresponding to all the optimal solutions of the geometric parameters of the coupled coil

[0125] C i The X corresponding to the closest to 1 i Is the optimal solution, that is, the optimal geometric parameters of the rounded rectangle coupled coil.

[0126] In this example, the coupled coil of the magnetic coupling resonant wireless power transmission system applicable to UAV charging is designed and its geometric parameters are optimized. The coupled coil is wound with Litz wire of 0.1mm*50. The receiving coil is installed on the UAV, and the transmitting coil is installed on the ground charging platform. The preset scenario is that the UAV automatically lands on the ground wireless charging platform after the battery runs out, and continues to perform tasks after the battery is fully charged.

[0127] (1) Determine the geometric parameters of the coupling mechanism and their constraint ranges. The designed planar coupled coil structure is shown in the appendix Figure 3As shown, in the general design process, after determining the inner diameter r1, half inner side length x1, and half side length y1 corresponding to the first turn of the coil, the coil design can be completed by using interval winding or tight winding. The half side length y1 corresponding to the first turn of the coil directly determines the size of the central hole of the coil. If the value of y1 is too small, the magnetic lines of force cannot be closed; if it is too large, it will affect the size of the receiving coil, which is not conducive to the integrated design of the receiving coil and the UAV fuselage in this example. Moreover, the magnetic field generated by the transmitting coil should pass through the receiving coil as much as possible. If the central hole of the transmitting coil is too large, a large amount of magnetic flux leakage will occur, affecting the coupling effect between the coils. After comprehensive consideration, the range of the half side length of the transmitting coil and the receiving coil is set between 6 mm and 12 mm. According to the constraint conditions of the rounded square coil in Equation (2), the ranges of the inner diameter and half inner side length of the coil can be roughly determined to be between 6.7 mm and 13.4 mm and between 3 mm and 6 mm, respectively. According to the UAV charging power requirement, based on the empirical formula between the inductance and the number of turns of the coil, combined with the value range of the inner and outer diameters of the rounded square coil, the number of turns of the transmitting coil can be roughly determined to be about 70 turns, with a floating range of 5 turns up and down; the number of turns of the receiving coil is 40 turns, with a floating range of 5 turns up and down.

[0128] Appendix 1 Decision Variables and Constraint Conditions for Coil Optimization

[0129]

[0130] (2) Perform multi-objective optimization solution

[0131] The objective function is:

[0132]

[0133] The constraint conditions are

[0134]

[0135] Set the maximum number of iterations G max (Take 200 in this example), the population size q (take 30 in this example), the mutation probability cp (take 0.4 in this example), and the crossover recombination probability mp (take 0.7 in this example) to perform the solution. The optimization results of the double-objective optimization of the coupling coefficient and internal resistance of the coupling coil are shown in the appendix Figure 6 as shown.

[0136] Evaluate and make decisions on the optimization results of the coupling coil, calculate the closeness C of the optimization results of the geometric parameters of each group of coupling coils i , and sort according to the C i value. The 21st design point obviously has a maximum value (C 21 = 0.819). Therefore, the optimal solution set obtains the optimal solution at this point. The optimal solution is as follows in the table:

[0137] Appendix 2 Design Scheme of Geometric Parameters of Coupling Coils

[0138]

[0139] After actual testing, the parameters of the coupling coil designed in this example are as follows: the inductance of the transmitting coil is 194.64 μH, the internal resistance is 1.24 Ω, the inductance of the receiving coil is 74.23 μH, the internal resistance is 0.48 Ω. When the axial distance between the transmitting coil and the receiving coil is 15 mm and they are in the facing position, the coupling coefficient is 0.683, which has good performance and can be used in the wireless charging technology of drones.

[0140] Refer to Appendix Figure 7 , based on the above embodiments, the present application further provides a design device for a wireless power transfer coupling coil. The design device 100 of the wireless power transfer coupling coil includes a topology analysis module 101, an expression construction module 102, a solution set solving module 103, and an optimal parameter determination module 104. Among them, the topology analysis module 101 is used to determine the optimization objective of the coupling coil mechanism based on the structure of the series-series resonance compensation topology of the magnetic coupling resonance wireless power transfer system. The optimization objective is to determine the coupling coil mechanism with the minimum internal resistance and the maximum coupling coefficient within the design constraints. Among them, the coupling coil mechanism includes a transmitting coil and a receiving coil, and both the transmitting coil and the receiving coil are wound with Litz wire; the expression construction module 102 is used to determine the rounded rectangle coupling coil model according to the constraint relationship between the geometric parameters of the rounded rectangle coupling coil, and construct the coupling coefficient expression and the internal resistance sum expression of the receiving coil and the transmitting coil of the rounded rectangle coupling coil according to the rounded rectangle coupling coil model. According to the optimization objective of the coupling coil mechanism, determine the optimization objective function of the rounded rectangle coupling coil, use the geometric parameter constraints of the rounded rectangle coupling coil as the design constraints, and obtain the parameter optimization problem to be solved based on the optimization objective function and the geometric parameter constraints; the solution set solving module 103 is used to randomly select the initial values of the geometric parameters to generate an initial population, and use the multi-objective genetic algorithm to solve the parameter optimization problem based on the initial population to obtain the optimal solution set of the geometric parameters of the rounded rectangle coupling coil; the optimal parameter determination module 104 is used to evaluate the optimal solution set of the geometric parameters using the entropy weight Topsis decision algorithm to obtain the optimal geometric parameters of the rounded rectangle coupling coil, and design the wireless power transfer coupling coil according to the optimal geometric parameters.

[0141] , based on the above embodiments, the present application further provides an electronic device. The electronic device includes: at least one processor, a memory, and an input-output unit; among them, the memory is used to store a computer program, and the processor is used to call the computer program stored in the memory to execute the design method of the wireless power transfer coupling coil provided by the method claims

[0142] The above are only the preferred embodiments of the present application, which do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A design method for a wireless power transfer coupling coil, characterized in that Including: Based on the structure of the series-series resonance compensation topology of the magnetic coupling resonant wireless power transfer system, determine the optimization objective of the coupling coil mechanism. The optimization objective is to determine the coupling coil mechanism with the minimum internal resistance and the maximum coupling coefficient within the design constraints. Among them, the coupling coil mechanism includes a transmitting coil and a receiving coil, and both the transmitting coil and the receiving coil are wound with Litz wire; According to the constraint relationship between the geometric parameters of the rounded rectangular coupling coil, determine the rounded rectangular coupling coil model, and construct the coupling coefficient expression and the internal resistance sum expression of the receiving coil and the transmitting coil of the rounded rectangular coupling coil according to the rounded rectangular coupling coil model. According to the optimization objective of the coupling coil mechanism, determine the optimization objective function of the rounded rectangular coupling coil, and use the geometric parameter constraints of the rounded rectangular coupling coil as the design constraints. Based on the optimization objective function and the geometric parameter constraints, obtain the parameter optimization problem to be solved; Randomly select the initial values of the geometric parameters to generate an initial population, and use the multi-objective genetic algorithm to solve the parameter optimization problem based on the initial population to obtain the optimal solution set of the geometric parameters of the rounded rectangular coupling coil; Use the entropy weight Topsis decision algorithm to evaluate the optimal solution set of the geometric parameters to obtain the optimal geometric parameters of the rounded rectangular coupling coil, and design the wireless power transfer coupling coil according to the optimal geometric parameters.

2. The design method of the wireless power transmission coupling coil according to claim 1, characterized in that The determining of the optimization objective of the coupling coil mechanism based on the topology of the series-series resonance compensation of the magnetic coupling resonant wireless power transfer system includes: Conduct circuit analysis on the topology of the series-series resonance compensation to obtain the transmission efficiency expression of the system. Among them, the transmission efficiency expression of the system is: Where, ω represents the angular frequency of the system; R L represents the load impedance; L T respectively represent the equivalent self-inductance of the transmitting coil, R T represents the internal resistance of the transmitting-end coupling coil; L R represents the equivalent self-inductance of the receiving coil; R R represents the internal resistance of the receiving coil; k represents the coupling coefficient between the transmitting coil and the receiving coil, and η represents the transmission efficiency; Based on a fixed load R L and the working angular frequency ω, key parameters affecting the transmission efficiency are obtained. The key parameters are the internal resistances of the transmitting coil and the receiving coil, and the coupling coefficient between the transmitting coil and the receiving coil; Based on the internal resistances of the transmitting coil and the receiving coil and the coupling coefficient between the transmitting coil and the receiving coil, determine the optimization objective of the coupling coil mechanism.

3. The design method of the wireless power transmission coupling coil according to claim 1, characterized in that, The expression of the constraint relationship between the geometric parameters of the rounded rectangular coupling coil is: Among them, a is the arc inner diameter, representing the distance from the center point of the transmitting coil / receiving coil to the four arcs, y is the half side length, representing the distance from the center point of the transmitting coil / receiving coil to the square side, and x is the half inner side length, representing the length of the square side of the transmitting coil / receiving coil excluding the arcs.

4. The design method of the wireless power transmission coupling coil according to claim 1, characterized in that The geometric parameters of the rounded rectangular coupling coil include: Coil turn number parameter, coil half inner side length parameter, coil half side length parameter, coil arc radius parameter.

5. The design method of the wireless power transfer coupling coil according to claim 1, characterized in that, The expression of the objective function includes the maximum coupling coefficient of the rounded rectangular coupling coil; The determination process of the expression of the coupling coefficient includes: Construct the mutual inductance expression of two coaxial single-turn transmitting coils and a single-turn receiving coil according to Neumann's formula; Construct the mutual inductance expression of the rounded rectangular coupling coil based on the sum expression of the mutual inductances between all coaxial single-turn coils; Construct the self-inductance expression of each turn of the transmitting coil / receiving coil of the rounded rectangular coupling coil according to the preset empirical formula; Based on the sum of the self-inductances and mutual inductances of each turn inside the transmitting coil / receiving coil, determine the equivalent self-inductance expression of each of the transmitting coil / receiving coil; According to the conversion relationship between the coupling coefficient expression of the coil, the mutual inductance expression of the coil, and the self-inductance expression of the coil, obtain the coupling coefficient expression of the rounded rectangular coupling coil.

6. The design method of the wireless power transfer coupling coil according to claim 1, characterized in that The expression of the objective function also includes the minimum internal resistance sum of the rounded rectangular coupling coil; the determination process of the expression of the internal resistance sum includes: Based on the preset total winding length expression and the coil AC internal resistance estimation expression, determine the expression of the internal resistance sum of the rounded rectangular coupling coil.

7. The design method of the wireless power transfer coupling coil according to claim 1, characterized in that The initial values of the geometric parameters are randomly selected to generate an initial population, and the multi-objective genetic algorithm is used based on the initial population to solve the parameter optimization problem, and the optimal solution set of the geometric parameters of the rounded rectangular coupling coil is obtained, including: Perform mutation operations on the geometric parameters in the parent population with a first preset probability, and perform crossover recombination operations with a second preset probability to generate a geometric parameter sequence as the offspring population. Combine the parent population and the offspring population to form a new population, calculate the function values corresponding to the offspring population according to the optimization objective function, perform fast non-dominated sorting and crowding degree sorting on the new population according to the function values, and select the current optimal geometric parameter sequence as the new parent population. Iteratively calculate the above steps until the iteration termination condition is reached, and obtain the optimal solution set of the geometric parameters of the rounded rectangular coupling coil.

8. The design method of the wireless power transmission coupling coil according to claim 1, characterized in that Using the entropy weight Topsis decision algorithm to evaluate the optimal solution set of geometric parameters to obtain the optimal geometric parameters of the rounded rectangular coupling coil, including: According to the optimal solution set of the geometric parameters of the coupling coil and the evaluation indexes of the coupling coefficient and the internal resistance sum of each optimal solution in the optimal solution set of geometric parameters, construct an original evaluation matrix. Use the element calculation formula of the preset decision matrix to process each element of the original evaluation matrix, determine each element of the decision matrix, and construct a decision matrix based on each element of the decision matrix. Based on the ratio of each element to the sum of the elements in its corresponding row, obtain the characteristic proportion of each element. Calculate the information entropy of each evaluation index based on the characteristic proportion of each element. Calculate the weights of each evaluation index based on each information entropy. Use the weights of the evaluation indexes to perform weighted processing on each element in the decision matrix to obtain a comprehensive evaluation matrix. Obtain the positive and negative ideal solutions of the evaluation indexes of the coupling coefficient and the coil internal resistance. Calculate the distances between the comprehensive evaluation matrix and the positive ideal solution and the negative ideal solution respectively. According to the distances between the positive ideal solution and the negative ideal solution, calculate the closeness degrees corresponding to all the optimal solutions, and use the geometric parameters corresponding to the optimal solution closest to 1 as the optimal geometric parameters of the rounded rectangular coupling coil.

9. A design device for a wireless power transmission coupling coil, characterized in that, Including: A topology analysis module, which is used to determine the optimization objective of the coupling coil mechanism based on the structure of the series-series resonance compensation topology of the magnetic coupled resonant wireless power transmission system. The optimization objective is to determine the coupling coil mechanism with the minimum internal resistance and the maximum coupling coefficient within the design constraints. Among them, the coupling coil mechanism includes a transmitting coil and a receiving coil, and both the transmitting coil and the receiving coil are wound with Litz wire; An expression construction module is used to determine a rounded rectangle coupled coil model according to the constraint relationship between the geometric parameters of the rounded rectangle coupled coil, construct the coupling coefficient expression and the internal resistance sum expression of the receiving coil and the transmitting coil of the rounded rectangle coupled coil based on the rounded rectangle coupled coil model, determine the optimization objective function of the rounded rectangle coupled coil according to the optimization objective of the coupled coil mechanism, use the geometric parameter constraints of the rounded rectangle coupled coil as design constraints, and obtain a parameter optimization problem to be solved based on the optimization objective function and the geometric parameter constraints; A solution set solving module is used to randomly select an initial value of geometric parameters to generate an initial population, solve the parameter optimization problem by using a multi-objective genetic algorithm based on the initial population, and obtain an optimal solution set of the geometric parameters of the rounded rectangle coupled coil; An optimal parameter determination module is used to evaluate the optimal solution set of geometric parameters by using an entropy weight Topsis decision algorithm, obtain the optimal geometric parameters of the rounded rectangle coupled coil, and design a wireless power transmission coupled coil according to the optimal geometric parameters.

10. An electronic device, characterized in that, The electronic device includes: At least one processor, a memory, and an input / output unit; Wherein, the memory is used to store a computer program, and the processor is used to call the computer program stored in the memory to execute the design method of the wireless power transmission coupled coil as described in claims 1-8.

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