Parameter design method for multi-relay wireless power supply system based on self-resonant coil

Abstract

The application provides a parameter design method of a multi-relay wireless power supply system based on a self-resonant coil, and is used for solving the difficulty in improving the coil quality factor and system efficiency of an existing multi-relay wireless power supply system. The specific steps are as follows: an equivalent series RLC circuit model of the self-resonant coil is constructed, the equivalent series RLC circuit model comprises an equivalent coil, a parasitic capacitor and a parasitic resistor which are connected in series; a parameter model of the equivalent coil, the parasitic capacitor and the parasitic resistor is constructed, a quality factor model of the self-resonant coil is constructed based on the parameter model of the equivalent coil, the parasitic capacitor and the parasitic resistor; the parameters of the self-resonant coil are calculated with the maximum quality factor as an optimization target; and the system working frequency and compensation parameters are calculated with the maximum system efficiency as an optimization target based on the parameters of the self-resonant coil. The application improves the quality factor of the coil and the transmission efficiency of the system, and simultaneously realizes the zero-phase-angle input and constant-voltage output of the system.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission technology, and in particular to a parameter design method for a multi-relay wireless power supply system based on a self-resonant coil. Background Technology

[0002] Transmission lines are the largest component of the power system, bearing the heavy responsibility of transmitting electrical energy. Online monitoring equipment can monitor and provide feedback on the status information of transmission lines in real time, and is a key link in ensuring the stable and reliable operation of transmission lines. With the further deployment of the "Power Internet of Things" and "Digital Grid" strategies, the application scenarios of online monitoring equipment are becoming increasingly complex, and the demand is gradually expanding. Ensuring stable power supply has become an important prerequisite for ensuring the reliable and efficient operation of the power grid.

[0003] Multi-relay wireless power supply systems can achieve efficient power transmission over long distances by adding several relay coils between the transmitting coil and the receiving self-resonant coil. In practical engineering applications, each coil is usually wound with Litz wire and resonates with an external independent capacitor. However, this scheme has the following problems: (1) the independent capacitor is easily damaged by compression during the insulation encapsulation process; (2) the independent capacitor is prone to parameter deviation when working under high voltage for a long time, which will destroy the coil resonance state; (3) the weight of the Litz wire wound coil is large, which poses a challenge to the mechanical strength of the insulator.

[0004] Self-resonant coils replace independent resonant capacitors with parasitic capacitance generated between two layers of spiral coils, offering the following advantages: (1) the parasitic capacitance is not damaged by pressure during the insulation encapsulation process; (2) self-resonant coils can operate reliably under high-voltage conditions; and (3) self-resonant coils are thin and lightweight, making them easy to install. However, self-resonant multi-relay wireless power supply systems still face many unresolved technical challenges.

[0005] First, improving the coil's quality factor (Q value) is difficult. Self-resonant coils have numerous parameters (including the number of turns, inner and outer diameters, line width, line spacing, dielectric layer thickness, copper foil thickness, and dielectric material), which are interconnected, and there is a lack of precise mathematical models to guide parameter design. In existing technologies, multilayer PCB coil structures significantly increase coil size to suppress proximity effects, which is detrimental to insulating packaging; while double single-layer self-resonant coil structures reduce dielectric losses, the significant reduction in parasitic capacitance causes the resonant frequency to rise to tens of MHz, posing additional challenges to switching devices. Most existing solutions rely on time-consuming finite element simulations for parameter optimization, resulting in long design cycles and high costs.

[0006] Secondly, improving system efficiency and achieving constant voltage output and zero-phase angle input are challenging. Online monitoring equipment has multiple operating modes (such as monitoring mode and sleep mode), requiring the power supply system to maintain constant voltage (CV) output under different load conditions. Simultaneously, zero-phase angle (ZPA) input can eliminate reactive current and improve transmission efficiency. However, the operating frequency of the self-resonant coil is limited by its self-resonant frequency, and the resonant capacitance originates from the coil's parasitic capacitance and cannot be flexibly adjusted. Currently, there is no method for designing compensation parameters for self-resonant multi-relay WPT systems.

[0007] Third, double-layer self-resonant coils are prone to deformation during insulation encapsulation and long-term operation. Self-resonant coils employ a double-layer PCB structure with a dielectric layer sandwiched between upper and lower copper foils. During high-voltage insulation encapsulation, shrinkage stress generated by the curing process of encapsulation materials such as epoxy resin, as well as thermal stress and mechanical vibration during long-term operation, can all lead to warping and delamination of the double-layer coil. Coil deformation alters the equivalent plate spacing of the parasitic capacitance, resulting in a shift in the coil's self-resonant frequency and disrupting the system's resonant operating state. Current technologies lack effective anti-deformation measures for double-layer self-resonant coils.

[0008] Fourth, when a multi-relay wireless power supply system is installed on the insulator strings of overhead transmission lines, the insulator strings will undergo flexible deformation under the influence of natural environmental factors such as wind deflection, icing, and galloping. This causes changes in the relative positions of the coils installed on the insulator strings, resulting in significant changes in the mutual inductance parameters between the coils. These changes in mutual inductance parameters will disrupt the original resonant compensation state of the system, causing the output voltage to deviate from the constant voltage target value and reducing the system's transmission efficiency. Existing self-resonant multi-relay WPT systems cannot adapt to the changes in mutual inductance parameters caused by the dynamic deformation of the insulator strings.

[0009] Therefore, there is an urgent need for a design method for a self-resonant multi-relay (WPT) system that can achieve accurate modeling of the self-resonant coil, high-efficiency Q-value optimization, and constant voltage output and zero phase angle input that can adapt to changes in the system's mutual inductance parameters. Summary of the Invention

[0010] The purpose of this invention is to provide a parameter design method for a multi-relay wireless power supply system based on a self-resonant coil. This method addresses the difficulties in improving the coil quality factor and system efficiency in existing multi-relay wireless power supply systems, as well as the complex technical challenges of achieving constant voltage output and zero-phase input.

[0011] A parameter design method for a multi-relay wireless power supply system based on a self-resonant coil, wherein the self-resonant coil comprises an upper copper foil, a lower copper foil, and a dielectric layer between the two layers; spiral copper wires are etched on both the upper and lower copper foils. The specific steps of the design method are as follows:

[0012] S1: Construct the equivalent series RLC circuit model of the self-resonant coil. The equivalent series RLC circuit model includes the equivalent inductance, parasitic capacitance and parasitic resistance connected in series.

[0013] S2: Construct parametric models of equivalent inductance, parasitic capacitance, and parasitic resistance, and construct a quality factor model of the self-resonant coil based on the parametric models of equivalent coil, parasitic capacitance, and parasitic resistance.

[0014] S3: Calculate the parameters of the self-resonant coil with the goal of maximizing the quality factor;

[0015] S4: Based on the parameters of the self-resonant coil, with the optimization objective of maximizing system efficiency, calculate the system operating frequency and compensation parameters.

[0016] Optionally, the quality factor model of the self-resonant coil is: ,in: The self-inductance of the equivalent coil, Parasitic resistance value:

[0017] ;

[0018] in, The dielectric loss tangent, The total length of the coil, Parasitic capacitance, For operating frequency, The spacing between the coil lines, To reach skin depth, The thickness of the copper foil in the self-resonant coil. The resistivity of copper; parasitic capacitance for:

[0019] ;

[0020] in, The vacuum permittivity, The relative permittivity of the dielectric material, This is the equivalent plate spacing of the self-resonant coil. For the thickness of the dielectric layer, This is the linewidth of the self-resonant coil.

[0021] Optionally, the specific steps in step S3 are as follows:

[0022] S3.1: Determine the size constraints and optimization parameters of the self-resonant coil based on the specific application scenario;

[0023] S3.2: Based on the established self-resonant coil Value model, combined with genetic algorithm, to maximize The objective is to optimize the parameters of a self-resonant coil with a fixed coil size.

[0024] Optionally, the optimized parameters of the self-resonant coil in step S3.1 include the outer diameter. , inner diameter Line width Line spacing Dielectric layer thickness Copper foil thickness Number of turns and the medium material;

[0025] The self-resonant coil size constraint includes: coil outer diameter. inner diameter of the coil Total coil thickness The line width and line spacing satisfy ;in: , and All are preset self-resonant coil size thresholds.

[0026] Optionally, a multi-relay wireless power supply system based on self-resonant coils includes a DC power supply, a high-frequency inverter, a transmitting self-resonant coil, a relay self-resonant coil, a receiving self-resonant coil, a compensating impedance, a high-frequency rectifier, and a load.

[0027] The DC power supply, high-frequency inverter, and transmitting self-resonant coil are connected in sequence; the receiving self-resonant coil, compensation impedance, high-frequency rectifier, and load are connected in sequence.

[0028] Optionally, the self-resonant coil includes an anti-deformation structure, which includes an auxiliary fixing bracket disposed between the upper copper foil and the lower copper foil of the coil.

[0029] The auxiliary fixing bracket is made of an electromagnetically transparent material with a relative permittivity close to 1 and a dielectric loss tangent less than 0.001. The self-resonant coil is encased in a packaged shell, and a hollow structure is formed in the packaged shell corresponding to the inner diameter region of the coil and the inter-turn region of the coil.

[0030] Optionally, the specific steps in step S4 are as follows:

[0031] S4.1: Given the parameters of a self-resonant multi-relay wireless power supply system, including coil self-inductance, inter-coil mutual inductance, input voltage, and self-resonant frequency. Frequency variation range and frequency variation step size ;

[0032] S4.2: Verify whether the system is in constant voltage output state at the current frequency. If not, calculate the system state at the next frequency point if constant voltage output is required. If constant voltage output is required, calculate the equivalent impedance of the receiving self-resonant coil that makes the system meet zero phase angle input at the current frequency, and determine the type of compensation impedance.

[0033] S4.3: Repeat step S4.2 to obtain the frequency of all constant voltage outputs within the frequency variation range and their equivalent compensation impedance;

[0034] S4.4: Calculate the system output voltage gain after adjusting the self-resonant coil to the equivalent compensated impedance. ;

[0035] S4.5: Calculate the system efficiency and output the operating frequency and compensation impedance parameters when the system efficiency is at its highest.

[0036] Optionally, in step S4.2, when the parasitic capacitance requires a change in compensation capacitance... At that time, series variable inductor As a compensation impedance; when the parasitic capacitance requires a change in compensation capacitance. At that time, series variable capacitor As a compensating impedance.

[0037] Optionally, the specific method in step S4.3 is as follows: Under the constraints of constant voltage output and zero phase angle input, at the self-resonant frequency... range of variation Inside, with As the starting frequency, with Given the frequency variation step size, calculate all parameter sets that meet the requirements.

[0038] Optionally, the compensation inductor and compensation capacitor are variable inductors and variable capacitors; when the multi-relay wireless power supply system is installed on a flexible insulator string, the method further includes step S6: adapting and adjusting the system parameters, the specific steps of which are as follows:

[0039] S5.1: Real-time detection of changes in mutual inductance between coils in flexible insulator strings caused by external interference;

[0040] S5.2: Based on the detected change in mutual inductance, calculate the total compensation impedance adjustment required to maintain the constant voltage output of the system;

[0041] S5.3: Distribute the total compensation impedance adjustment amount to the variable inductor or variable capacitor connected in series with the receiving self-resonant coil, and adjust the inductance value of the variable inductor or the capacitance value of the variable capacitor so that the system maintains constant voltage output and zero phase angle input under different mutual inductance conditions.

[0042] S5.4: Repeat steps S5.1 to S5.3 to achieve adaptive adjustment of system parameters of flexible insulator strings under dynamic deformation conditions.

[0043] Because of the adoption of the above technical solution, the present invention has the following advantages:

[0044] 1. This application eliminates the reliance on finite element simulation by using precise mathematical modeling of the self-resonant coil; the modified parasitic capacitance model reduces the calculation error from 31.5% to less than 3.2%; and clarifies the criterion that the proximity effect is negligible. A complete parasitic resistance model was established; based on this mathematical model, purely analytical coil parameter optimization can be performed, which can significantly shorten the design cycle and reduce manufacturing costs.

[0045] 2. This application significantly improves the coil quality factor under fixed size constraints. Furthermore, this application employs the simplest two-layer structure, achieving performance comparable to complex multi-layer structures within a small size. This value is beneficial for insulating encapsulation.

[0046] 3. The parameter design method of this application simultaneously realizes constant voltage output and zero phase angle input. The system maintains constant voltage output under different load conditions, while realizing zero phase angle input and zero voltage switching, which effectively improves system efficiency.

[0047] 4. When the system is installed on a flexible insulator string, this application can detect changes in mutual inductance between coils in real time caused by wind deflection, icing, or galloping. By adaptively adjusting the variable inductance on the transmitting side and the variable capacitor on the receiving side, it can maintain constant voltage output and zero phase angle input under dynamic deformation conditions, which significantly enhances the system's adaptability to complex outdoor environmental conditions.

[0048] 5. This application addresses the problem of deformation of double-layer self-resonant coils during insulation encapsulation and long-term operation by proposing an anti-deformation structure that combines electromagnetic transparent material-assisted fixation with hollow encapsulation. The electromagnetic transparent support provides mechanical support while having almost no impact on the electromagnetic field distribution of the coil. The hollow encapsulation effectively reduces the influence of the encapsulation material on parasitic parameters, ensuring the long-term stability of coil parameters and improving the system's operational reliability and service life under harsh conditions such as high voltage and temperature difference cycling.

[0049] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0050] The accompanying drawings of this invention are described below.

[0051] Figure 1 This is a schematic diagram of the structure of the self-resonant coil of the present invention.

[0052] Figure 2 This is a diagram showing the terminal connection configuration of the self-resonant coil of the present invention.

[0053] Figure 3 This is a schematic diagram of the self-resonant coil anti-deformation structure of the present invention.

[0054] Figure 4 This is a flowchart of the parameter design method for the multi-relay wireless power supply system of the present invention.

[0055] Figure 5 This is the RLC equivalent circuit model diagram of the self-resonant coil of the present invention.

[0056] Figure 6 This is a schematic diagram of the electric field distribution of the parallel plate capacitor and the self-resonant coil of this invention.

[0057] Figure 7 This is a schematic diagram illustrating the effect of the coil structure of this invention on parasitic capacitance.

[0058] Figure 8 This is a comparison chart of the parasitic capacitance model and simulation results before and after the modification of this invention.

[0059] Figure 9 This is a comparison diagram of the effects of different coil structures on parasitic resistance in this invention.

[0060] Figure 10 This is a comparison chart of the theoretical and simulated values ​​of the parasitic resistance of this invention.

[0061] Figure 11 This is a flowchart of the design method for the system operating frequency and compensation parameters of the present invention.

[0062] Figure 12 This is a schematic diagram of the structure of the self-resonant multi-relay WPT system of the present invention.

[0063] Figure 13 This is a circuit model diagram of the self-resonant multi-relay WPT system of the present invention.

[0064] Figure 14 This is a diagram of the two-port network equivalent circuit of the self-resonant multi-relay WPT system of the present invention.

[0065] Figure 15 This is a graph showing the relationship between the voltage gain and the input phase angle of this invention.

[0066] Figure 16 This is a comparison chart of the measured, theoretical, and simulation results of the impedance amplitude-frequency characteristics of the self-resonant coil of this invention.

[0067] 1-Self-resonant coil; 2-Auxiliary fixing bracket; 3-Encapsulation housing; 4-Hollow structure. Detailed Implementation

[0068] The present invention will be further described below with reference to the accompanying drawings and embodiments. The terms "connected" and "linked" should be interpreted broadly, for example, they can be fixed connections, detachable connections, integral connections, electrical connections, or signal connections; they can be direct connections or indirect connections through an intermediate medium.

[0069] Example 1:

[0070] A multi-relay wireless power supply system based on self-resonant coils includes a DC power supply, a high-frequency inverter, a transmitting self-resonant coil, a relay self-resonant coil, a receiving self-resonant coil, a compensation impedance, a high-frequency rectifier, and a load.

[0071] The transmitting self-resonant coil is connected to the output terminal of the high-frequency inverter, and the input terminal of the high-frequency inverter is connected to the DC power supply; the receiving self-resonant coil is connected to the input terminal of the high-frequency rectifier through a compensated impedance, and the output terminal of the high-frequency rectifier is connected to the load.

[0072] like Figure 1 and Figure 2 As shown, the transmitting, relaying, and receiving self-resonant coils all employ a double-layer PCB structure, including an upper copper foil layer, a lower copper foil layer, and a dielectric layer between the two layers. Spiral copper wires are etched onto both the upper and lower copper foil layers. The geometric parameters of the self-resonant coil include: outer diameter... , inner diameter Line width Line spacing Dielectric layer thickness Copper foil thickness Number of turns The compensation impedance is either a compensation capacitor or a compensation inductor.

[0073] As one embodiment of this application, such as Figure 3 As shown, Figure 3 (a) is a schematic diagram of the internal structure of the encapsulation housing 3. Figure 3 (b) is a schematic diagram of the encapsulation housing 3. The self-resonant coil 1 includes an anti-deformation structure, which includes an auxiliary fixing bracket 2 disposed between the upper copper foil and the lower copper foil of the coil;

[0074] The auxiliary fixing bracket 2 is made of electromagnetic transparent material, the relative permittivity of which is close to 1 and the dielectric loss tangent is less than 0.001. The self-resonant coil is covered with an encapsulation shell 3, and a hollow structure 4 is opened in the encapsulation shell corresponding to the inner diameter area of ​​the coil and the inter-turn area of ​​the coil.

[0075] In this embodiment, the auxiliary fixing bracket 2 provides mechanical support without affecting the electromagnetic field distribution of the coil, preventing deformation of the double-layer coil during insulation encapsulation and long-term operation. The electromagnetically transparent material is a low-dielectric-constant, low-loss polymer material such as cyclic olefin copolymer (COC) and polyimide aerogel (PIA). The opening position and size of the hollow structure 4 are determined according to the electromagnetic field distribution of the coil to reduce the influence of the encapsulation material on the parasitic parameters of the coil. The hollow structure 4 includes through-holes on the upper and / or lower cover plates of the encapsulation shell corresponding to the inner diameter region of the coil, and intermittent slots corresponding to the inter-turn region of the coil.

[0076] Example 2:

[0077] like Figure 4 The parameter design method for a multi-relay wireless power supply system based on a self-resonant coil includes the following steps:

[0078] S1: Construct the equivalent series RLC circuit model of the self-resonant coil, such as... Figure 5 As shown, the equivalent series RLC circuit model includes an equivalent coil, parasitic capacitance, and parasitic resistance connected in series.

[0079] S2: Construct parametric models of the equivalent coil, parasitic capacitance, and parasitic resistance; based on these models, construct a quality factor model for the self-resonant coil. The specific steps are as follows:

[0080] S2.1: The self-inductance of the equivalent coil constructed using a planar spiral inductor The parameter model is:

[0081]

[0082] in, Let be the magnetic permeability of copper.

[0083] S2.2: Parasitic capacitance The modeling considers the influence of the spiral structure on the electric field distribution. For example... Figure 6 As shown, Figure 6 In diagram (a), the electric field distribution of a parallel-plate capacitor is shown; in diagram (b), the electric field distribution of a self-resonant coil is shown. Figure 6 It can be seen that the electric field distribution of a self-resonant coil differs from that of a parallel-plate capacitor (the electric field direction is no longer perpendicular to the plates), resulting in an equivalent plate spacing. Greater than the thickness of the dielectric layer Equivalent plate spacing With line width and line spacing Relationship such as Figure 7 As shown, when When approaching infinity ;when Approaching 1 The maximum value has been reached. (Corrected parasitic capacitance) The parameter model is:

[0084]

[0085] in, The total length of the coil, ; The vacuum permittivity, is the relative permittivity of the dielectric material.

[0086] like Figure 8 As shown, the maximum error of the corrected parasitic capacitance model is only 3.2%, which is far better than the 31.5% error of the uncorrected model.

[0087] S2.3: The parasitic resistance From low-frequency DC resistor High-frequency AC resistors and dielectric loss resistance composition:

[0088]

[0089] in, , The resistivity of the copper foil; , The dielectric loss tangent, For operating frequency, , It is a proximity effect resistor. For skin effect resistance, Represented as:

[0090]

[0091] in, For skin depth.

[0092] like Figure 9 As shown, when At this point, as the linewidth increases, the resistance of the self-resonant coil decreases, and the proximity effect on the resistance becomes negligible. Therefore, the parasitic resistance of the self-resonant coil can be expressed as:

[0093]

[0094] like Figure 10 As shown, when The proximity effect has little effect on the parasitic resistance of a self-resonant coil; when When compared with the simulation results, the error of the proposed self-resonant coil resistance model is close to 0.

[0095] S2.4: Quality Factor ,in, The operating angular frequency is the frequency at which the self-resonant frequency is equal to the operating frequency. Therefore, the self-resonant coil The value is represented as:

[0096]

[0097] S3: Calculate the parameters of the self-resonant coil with the goal of maximizing the quality factor; the specific steps are as follows:

[0098] S3.1: Determine the size constraints and optimization parameters of the self-resonant coil based on the specific application scenario;

[0099] In this embodiment, the coil size constraint includes: coil outer diameter inner diameter of the coil Total coil thickness The line width and line spacing satisfy The optimized parameters include the outer diameter. , inner diameter Line width Line spacing Dielectric layer thickness Copper foil thickness Number of turns and dielectric materials ( and ).

[0100] S3.2: Based on the established self-resonant coil Value model, combined with genetic algorithm, to maximize The objective is to optimize the parameters of a self-resonant coil with a fixed coil size.

[0101] S4: Based on the parameters of the self-resonant coil, and with the goal of maximizing system efficiency, calculate the system operating frequency and compensation parameters. For example... Figure 11 As shown, the specific steps are as follows:

[0102] S4.1: Given the parameters of a self-resonant multi-relay wireless power supply system, including coil self-inductance, inter-coil mutual inductance, input voltage, and self-resonant frequency. Frequency variation range and frequency variation step size ;

[0103] In this embodiment, the given parameters of the self-resonant multi-relay wireless power supply system include input voltage, self-resonant frequency coil, coil self-inductance, coil internal resistance, and coil mutual inductance (mutual inductance of adjacent coils, mutual inductance of the next adjacent coil, ..., mutual inductance of the farthest coil).

[0104] In this embodiment, when designing system parameters, the equivalent circuit model of the two-port network of the self-resonant multi-relay WPT system is first established. The system equations are then established based on Kirchhoff's voltage law, and the system input impedance is derived. Voltage gain and transmission efficiency The expression for system losses includes inverter losses, rectifier losses, and coil losses.

[0105] S4.2: Verify whether the system is in constant voltage output state at the current frequency. If not, calculate the system state at the next frequency point if constant voltage output is required. If constant voltage output is required, calculate the equivalent impedance of the receiving self-resonant coil that makes the system meet zero phase angle input at the current frequency, and determine the type of compensation impedance.

[0106] In this embodiment, the constant voltage output condition is the voltage gain. Maintain a constant load (change less than a preset threshold, such as 10%); the zero-phase input condition is the phase angle of the input impedance. ,Right now: .

[0107] In this embodiment, since the parasitic capacitance of the self-resonant coil is fixed, the equivalent impedance of the receiving self-resonant coil is changed by connecting an external compensation impedance in series on the receiving self-resonant coil side. The required compensation capacitance change is determined by the amount of parasitic capacitance. At that time, series compensation inductor As a compensating impedance; compensating inductance satisfy:

[0108]

[0109] When the parasitic capacitance requires a change in compensation capacitance At that time, series compensation capacitor As compensation impedance; compensation capacitor satisfy:

[0110]

[0111] in, The equivalent impedance of the self-resonant coil is received after series compensation impedance.

[0112] S4.3: Repeat step S4.2 to obtain the frequency of all constant voltage outputs within the frequency variation range and their equivalent compensation impedance;

[0113] In this embodiment, under the condition of constant voltage output ( ) and zero phase input ( Under the constraint of ), at the self-resonant frequency range of variation Inside, with Given the frequency variation step size, calculate all parameter sets that meet the requirements.

[0114] S4.4: Calculate the system output voltage gain after adjusting the self-resonant coil to the equivalent compensated impedance. ;

[0115] S4.5: Calculate the system efficiency and output the operating frequency and compensation impedance parameters when the system efficiency is at its highest.

[0116] S5: Experimental Verification:

[0117] S5.1: Coil quality factor Value optimization experiment:

[0118] This experiment uses the dimensional constraints of a 35kV insulator as an example for illustration. Figure 12 As shown, the outer diameter of the insulator's large shed is 220mm, the core rod diameter is 30mm, and the shed thickness is 20mm. To allow space for insulation encapsulation, the coil dimensions are constrained as follows: , Total coil thickness .

[0119] At a working frequency of 1MHz, the skin depth is 65.2μm. When the copper foil thickness exceeds the skin depth... The value improvement is slow; considering both performance and cost, a copper foil thickness of 2 oz (approximately 70 μm) is chosen. The loss tangent of the dielectric material is... right The value has a significant impact—when using FR4 The value is only about 39, when using high-frequency, low-loss materials such as Rogers RO3003. The value can exceed 80. Rogers RO3003 was used as the medium in this experiment.

[0120] Based on the above constraints, to maximize The objective is to use a genetic algorithm to determine the number of turns. , inner diameter Line width Line spacing Dielectric layer thickness The parameters were optimized. A comparison of the parameters before and after optimization is shown in Table 1.

[0121] Table 1 Comparison of parameters before and after coil optimization

[0122]

[0123] As shown in Table 1, after optimization The value increased from 37 to 110.2, an increase of 197.8%.

[0124] S5.2: Experiment on self-resonant multi-relay WPT system and compensation parameter design:

[0125] like Figure 13-14 As shown in Table 2, this experiment constructs a five-stage self-resonant multi-repeater WPT system. The parameters of each coil are shown in Table 2. Figure 15 As shown, near the self-resonant frequency, the input impedance angle is not zero when the system satisfies the constant voltage output condition. To achieve both constant voltage output and zero phase angle input simultaneously, this embodiment connects an external compensation impedance in series on the receiving self-resonant coil side.

[0126] Based on the two-port network model of the system, the input impedance Z is derived. in The expression. When Im(Z) in When the phase angle is 0, the system satisfies the zero-phase input condition. The equivalent impedance of the receiving self-resonant coil is changed by connecting a series compensation inductor L' or a compensation capacitor C'. The specific steps are as follows:

[0127] Step 1: In Within the range This refers to the step-size scanning frequency.

[0128] Step 2: For each frequency point, determine whether the constant voltage output condition is met (voltage gain G is in the range of 0.8~1.2).

[0129] Step 3: If the constant voltage output condition is met, calculate the series compensation impedance value required to achieve zero phase angle input;

[0130] Step 4: Calculate the system efficiency and select the operating frequency and compensation impedance parameters that provide the highest efficiency.

[0131] Table 2 Parameter Table of Self-Resonant Multi-Relay WPT System

[0132]

[0133] The optimization results obtained through the above steps are shown in Table 3.

[0134] S5.3: A prototype self-resonant multi-relay WPT system was built. The high-frequency inverter uses four GaN MOSFETs (EPC2016C), and the high-frequency rectifier uses four Schottky diodes (VSSAF3M10HM3 / H). The transmitting coil is connected to the inverter, and the receiving self-resonant coil is connected via a compensation inductor. The rectifier is then connected. Each coil is installed along the center rod with a spacing of 450mm.

[0135] like Figure 16 As shown, the measured results of the impedance characteristics of the self-resonant coil are highly consistent with the theoretical calculations and simulation results, verifying the accuracy of the mathematical model established in this invention.

[0136] The load was tested. The system output voltages are shown for 30Ω, 50Ω, 70Ω, and 90Ω loads. Within a load variation range of 30Ω to 90Ω, the system output voltage ranges from 43.8V to 47.4V, with a variation of less than 10%, verifying that the method of this invention achieves constant voltage output. Furthermore, zero-voltage switching (ZVS) is achieved under different load conditions, verifying that the system operates in a zero-phase input state.

[0137] Table 3. Optimization Results of Compensation Parameters for Self-Resonant Multi-Relay WPT System

[0138]

[0139] The load was tested. When the voltage changes abruptly between 80Ω and 150Ω, the output voltage changes from 49.2V to 52.8V, a change of less than 10%, verifying that the system can still maintain constant voltage output under dynamic load conditions.

[0140] Under load The system efficiency reaches its maximum of 69.6% at 45Ω, with an output power of 41W.

[0141] Compared with existing self-resonant coil technology, this application achieves [the following] while maintaining a small size (100×100mm²) and a simple double-layer structure. The superior performance of this system is evident. Compared with existing self-resonant multi-relay WPT systems, this application achieves constant voltage output functionality.

[0142] In summary, this invention achieves purely analytical coil parameter optimization by establishing a precise mathematical model, eliminating the need for time-consuming finite element simulation. By connecting an external compensation impedance in series with the receiving self-resonant coil, it simultaneously achieves constant voltage output and zero-phase angle input in a self-resonant multi-relay system, effectively improving system efficiency. This application provides a practical and low-cost wireless power supply solution for online monitoring equipment of high-voltage transmission lines.

[0143] Example 3:

[0144] A parameter adaptation method for a flexible insulator string, wherein a multi-relay wireless power supply system is installed on the flexible insulator string, and the multi-relay wireless power supply system is designed using the parameter design method described in Example 2; the compensation inductor and compensation capacitor are variable inductors and variable capacitors; the specific steps of the parameter adaptation method are as follows:

[0145] S1: Real-time detection of changes in mutual inductance between coils in flexible insulator strings caused by external interference;

[0146] S2: Based on the detected change in mutual inductance, calculate the total compensation impedance adjustment required to maintain the constant voltage output of the system;

[0147] S3: Distribute the total compensation impedance adjustment amount to the variable inductor or variable capacitor connected in series with the receiving self-resonant coil, and adjust the inductance value of the variable inductor or the capacitance value of the variable capacitor so that the system maintains constant voltage output and zero phase angle input under different mutual inductance conditions.

[0148] S4: Repeat steps S5.1 to S5.3 to achieve adaptive adjustment of system parameters of flexible insulator strings under dynamic deformation conditions.

[0149] In this embodiment, the adjustment range of the inductance value of the variable inductor and the adjustment range of the capacitance value of the variable capacitor are determined according to the mutual inductance change range corresponding to the maximum expected deformation of the flexible insulator string. Initially, the values ​​of the variable inductor or variable capacitor are adjusted according to the parameters designed in step embodiment 2. When external disturbances (wind deflection, icing, or galloping) occur, the system satisfies constant voltage output and zero phase angle input by adaptively adjusting the parameters.

[0150] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A parameter design method for a multi-relay wireless power supply system based on a self-resonant coil, wherein the self-resonant coil comprises an upper copper foil, a lower copper foil, and a dielectric layer between the two layers; spiral copper wires are etched on both the upper and lower copper foils, characterized in that, The specific steps of the design method are as follows: S1: Construct the equivalent series RLC circuit model of the self-resonant coil. The equivalent series RLC circuit model includes the equivalent inductance, parasitic capacitance and parasitic resistance connected in series. S2: Construct parametric models of equivalent inductance, parasitic capacitance, and parasitic resistance, and construct a quality factor model of the self-resonant coil based on the parametric models of equivalent coil, parasitic capacitance, and parasitic resistance. S3: Calculate the parameters of the self-resonant coil with the goal of maximizing the quality factor; S4: Based on the parameters of the self-resonant coil, with the optimization objective of maximizing system efficiency, calculate the system operating frequency and compensation parameters.

2. The parameter design method for a multi-relay wireless power supply system based on a self-resonant coil according to claim 1, characterized in that, The quality factor model of the self-resonant coil is as follows: ,in: The self-inductance of the equivalent coil, Parasitic resistance value: ； in, The dielectric loss tangent, The total length of the coil, Parasitic capacitance, For operating frequency, The spacing between the coil lines, To reach skin depth, The thickness of the copper foil in the self-resonant coil. The resistivity of copper; parasitic capacitance for: ； in, The vacuum permittivity, The relative permittivity of the dielectric material, This is the equivalent plate spacing of the self-resonant coil. For the thickness of the dielectric layer, This is the linewidth of the self-resonant coil.

3. The parameter design method for a multi-relay wireless power supply system based on a self-resonant coil according to claim 1, characterized in that, The specific steps in step S3 are as follows: S3.1: Determine the size constraints and optimization parameters of the self-resonant coil based on the specific application scenario; S3.2: Based on the established self-resonant coil Value model, combined with genetic algorithm, to maximize The objective is to optimize the parameters of a self-resonant coil with a fixed coil size.

4. The parameter design method for a multi-relay wireless power supply system based on a self-resonant coil according to claim 3, characterized in that, The optimized parameters of the self-resonant coil mentioned in step S3.1 include the outer diameter. , inner diameter Line width Line spacing Dielectric layer thickness Copper foil thickness Number of turns and the medium material; The self-resonant coil size constraint includes: coil outer diameter. inner diameter of the coil Total coil thickness The line width and line spacing satisfy ;in: , and All are preset self-resonant coil size thresholds.

5. The parameter design method for a multi-relay wireless power supply system based on a self-resonant coil according to claim 1, characterized in that, A multi-relay wireless power supply system based on self-resonant coils includes a DC power supply, a high-frequency inverter, a transmitting self-resonant coil, a relay self-resonant coil, a receiving self-resonant coil, a compensating impedance, a high-frequency rectifier, and a load. The DC power supply, high-frequency inverter, and transmitting self-resonant coil are connected in sequence; the receiving self-resonant coil, compensation impedance, high-frequency rectifier, and load are connected in sequence.

6. The parameter design method for a multi-relay wireless power supply system based on a self-resonant coil according to claim 1 or 5, characterized in that, The self-resonant coil includes a deformation-resistant structure, which includes an auxiliary fixing bracket disposed between the upper copper foil and the lower copper foil of the coil. The auxiliary fixing bracket is made of an electromagnetically transparent material with a relative permittivity close to 1 and a dielectric loss tangent less than 0.

001. The self-resonant coil is encased in a shell, and the area corresponding to the inner diameter of the coil and the area between coil turns inside the shell has a hollow structure.

7. The parameter design method for a multi-relay wireless power supply system based on a self-resonant coil according to claim 5, characterized in that, The specific steps in step S4 are as follows: S4.1: Given the parameters of a self-resonant multi-relay wireless power supply system, including coil self-inductance, inter-coil mutual inductance, input voltage, and self-resonant frequency. Frequency variation range and frequency variation step size ; S4.2: Verify whether the system is in constant voltage output state at the current frequency. If not, calculate the system state at the next frequency point for constant voltage output. If constant voltage output is satisfied, calculate the equivalent impedance of the receiving self-resonant coil that makes the system meet zero phase angle input at the current frequency, and determine the type of compensation impedance; S4.3: Repeat step S4.2 to obtain the frequency of all constant voltage outputs within the frequency variation range and their equivalent compensation impedance; S4.4: Calculate the system output voltage gain after adjusting the self-resonant coil to the equivalent compensated impedance. ; S4.5: Calculate the system efficiency and output the operating frequency and compensation impedance parameters when the system efficiency is at its highest.

8. The parameter design method for a multi-relay wireless power supply system based on a self-resonant coil according to claim 7, characterized in that, In step S4.2, when the parasitic capacitance requires a change in compensation capacitance... At that time, series compensation inductor As a compensation impedance; when the parasitic capacitance requires a change in compensation capacitance. At that time, series compensation capacitor As a compensating impedance.

9. The parameter design method for a multi-relay wireless power supply system based on a self-resonant coil according to claim 7, characterized in that, The specific method in step S4.3 is as follows: Under the constraints of constant voltage output and zero phase angle input, at the self-resonant frequency... range of variation Inside, with As the starting frequency, with Given the frequency variation step size, calculate all parameter sets that meet the requirements.

10. A parameter adaptation method for a flexible insulator string, wherein a multi-relay wireless power supply system is installed on the flexible insulator string, characterized in that, The multi-relay wireless power supply system is designed using the parameter design method described in any one of claims 1-9; the compensation inductor and compensation capacitor are variable inductors and capacitors; the specific steps of the parameter adaptation method are as follows: S5.1: Real-time detection of changes in mutual inductance between coils in flexible insulator strings caused by external interference; S5.2: Based on the detected change in mutual inductance, calculate the total compensation impedance adjustment required to maintain the constant voltage output of the system; S5.3: Distribute the total compensation impedance adjustment amount to the variable inductor or variable capacitor connected in series with the receiving self-resonant coil, and adjust the inductance value of the variable inductor or the capacitance value of the variable capacitor so that the system maintains constant voltage output and zero phase angle input under different mutual inductance conditions. S5.4: Repeat steps S5.1 to S5.3 to achieve adaptive adjustment of system parameters of flexible insulator strings under dynamic deformation conditions.

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