Multi-coil inductor and production process thereof

Abstract

The invention relates to the technical field, and discloses a multi-coil inductor and a production technology thereof.The method comprises the steps that a magnetic conductivity material is selected to prepare an EE type magnetic core, and an air gap is formed in the center position of a magnetic core center column; the number of turns, the wire diameter and the winding mode of each coil winding are designed, and an insulating layer is arranged between every two adjacent coil windings; dividing the total magnetic flux into a plurality of equivalent magnetic fluxes by adopting a magnetic field division method, and respectively calculating the magnetic fluxes of all parts and the influence of the magnetic fluxes on the magnetic resistance; the wire diameter and the paint thickness of the coil winding are optimized through finite element analysis, and the self-tuning frequency of the inductor is improved; coil winding is carried out by adopting automatic winding equipment, so that uniform and stable winding is realized; and selecting a packaging material, and packaging the inductor by adopting a vacuum packaging technology. The multi-coil inductor has the advantages of being excellent in high-frequency performance, low in parasitic parameter, uniform in magnetic field distribution and high in packaging reliability, and is suitable for various high-frequency application scenes.

Description

Technical Field

[0001] This invention relates to the field of electronic component technology, and in particular to a multi-coil inductor and its manufacturing process. Background Technology

[0002] Traditional inductor manufacturing processes have shortcomings in core selection and structural design. The core materials typically used have low permeability, and the core structure is simple, lacking optimized air gap design. This design cannot effectively improve the inductor's self-resonant frequency, limiting its performance in applications operating at frequencies above 1MHz. Furthermore, the coil winding design in traditional processes is relatively crude, failing to fully consider the impact of the operating frequency on the winding method, resulting in larger parasitic inductance and capacitance, affecting the inductor's efficiency and stability.

[0003] In existing technologies, the number of turns, wire diameter, and winding method of coil windings often rely on empirical formulas, lacking precise optimization methods. For applications operating at frequencies above 1MHz, traditional winding methods cannot effectively reduce the impact of parasitic parameters; while for low-frequency applications, space utilization is not optimized, resulting in a large inductor size. Furthermore, the insulation between adjacent coil windings is inadequate, easily generating electromagnetic interference and interlayer capacitance, further affecting inductor performance.

[0004] In existing inductor manufacturing processes, the optimization of magnetic field distribution is a weak link. Traditional processes do not employ a magnetic field segmentation method to subdivide the total magnetic flux, making it impossible to accurately calculate the flux of each part and its impact on reluctance. This coarse magnetic field treatment results in the underutilization of the magnetic properties of the core, insufficient flexibility in adjusting magnetic circuit parameters, and difficulty in meeting the requirements of high-performance inductors.

[0005] In the packaging of inductors, existing technologies typically employ simple packaging materials and processes, which cannot effectively isolate the inductor's performance from the influence of the external environment. Excessive air residue during packaging can lead to decreased insulation performance and instability in the inductor's self-resonant frequency.

[0006] Therefore, this invention proposes a multi-coil inductor and its manufacturing process. By optimizing the core design, coil winding design, magnetic field distribution, and packaging technology, it solves the problems existing in the prior art and improves the performance and reliability of the inductor. Summary of the Invention

[0007] The purpose of this invention is to address the problems of insufficient inductor performance, unreasonable magnetic field distribution, and poor packaging reliability in the prior art by proposing a multi-coil inductor and its manufacturing process.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a manufacturing process for a multi-coil inductor, comprising the following steps: Step S1: Select a permeability material to prepare an EE-type magnetic core, open an air gap at the center of the core's central column, and increase the inductor's self-resonant frequency by adjusting the length of the air gap; Step S2: Design the number of turns, wire diameter, and winding method for each coil winding, and set an insulation layer between adjacent coil windings; Step S3: The total magnetic flux is divided into multiple equivalent magnetic fluxes using the magnetic field segmentation method, and the magnetic flux of each part and its influence on magnetic reluctance are calculated respectively. Step S4: Optimize the wire diameter and enamel thickness of the coil winding through finite element analysis to improve the self-resonant frequency of the inductor; Step S5: The coil is wound using an automated winding device. During the winding process, the current distribution and temperature changes are monitored in real time to achieve a uniform and stable winding. Step S6: Select packaging material, use vacuum packaging technology to package the inductor, and measure the self-resonant frequency of the inductor using a network analyzer.

[0009] Furthermore, step S1 also includes the following sub-steps: S1-1, Select a magnetic permeability material with a relative permeability of 10000 or higher as the core material. The magnetic permeability material includes silicon steel sheet, iron-based nanocrystalline alloy, amorphous alloy, permalloy and iron-based soft magnetic composite material. S1-2, the core material is cut and EE-shaped core is formed by pressing process. The EE-shaped core is composed of two E-shaped parts. Each E-shaped part includes a central post and two side posts. The two E-shaped parts are aligned and combined together through the central post. S1-3, An air gap is machined at the center of the central column of the EE-type magnetic core to achieve symmetrical and uniform magnetic field distribution. The width of the air gap is 0.1mm to 1mm, and the length of the air gap satisfies the following formula: Where g is the length of the air gap. Let be the free permeability, and A be the cross-sectional area of ​​the magnetic core. The relative permeability of the core material. For the target self-resonant frequency, This is the initial self-resonant frequency.

[0010] Furthermore, step S2 also includes the following sub-steps: S2-1, Design the number of turns for each coil winding. The specific calculation formula is as follows: Where N is the number of turns in each coil winding, L is the inductance, s is the magnetic path length, and A is the cross-sectional area of ​​the magnetic core. ρ is the permeability of the magnetic core; S2-2, Design the wire diameter for each coil winding. The specific calculation formula is as follows: Where J is the current density and d is the wire diameter. It is the maximum current density allowed by the material; S2-3, design the winding method of each coil winding. For applications with operating frequencies above 1MHz, parallel winding is adopted to reduce parasitic inductance and capacitance. For applications with operating frequencies below 1MHz, layered winding is adopted to optimize space utilization. S2-4, An insulating layer is set between adjacent coil windings using insulating materials to reduce electromagnetic interference and interlayer capacitance between coils. The insulating materials include polyimide film, polytetrafluoroethylene, polyester film, polypropylene film, silicone rubber, epoxy resin, polystyrene, and polycarbonate.

[0011] Furthermore, step S3 also includes the following sub-steps: S3-1, the total magnetic flux is divided into n equivalent magnetic fluxes using the magnetic field segmentation method. The specific calculation formula is as follows: in, Let n be the total magnetic flux, and n be the number of magnetic flux segments. The equivalent magnetic flux after segmentation, where i is an index used to distinguish different parts of the magnetic core; S3-2, calculate the magnetic induction intensity of each equivalent magnetic flux in the center post, side post, and air gap of the magnetic core, respectively. The specific calculation formula is as follows: in, It is the magnetic flux density of the i-th part of the magnetic core. It is the cross-sectional area of ​​the i-th part of the magnetic core; S3-3, Based on the distribution of magnetic flux in each part, calculate its impact on magnetic reluctance. The specific calculation formula is as follows: Where s is the magnetic circuit length and A is the cross-sectional area of ​​the magnetic core. ρ is the permeability of the magnetic core.

[0012] Furthermore, step S4 also includes the following sub-steps: S4-1. A three-dimensional model of the inductor is established using finite element analysis software, and material properties are defined. The three-dimensional model includes a magnetic core, an air gap, a coil winding, and an insulating layer. The material properties include the permeability of the magnetic core, the conductivity of the coil, the dielectric constant of the coating, and the loss factor. S4-2, The three-dimensional model of the inductor is meshed and refined to capture electromagnetic field characteristics, including the gradient change of magnetic field strength, the distribution of current density, and the propagation characteristics of electromagnetic field in different media. S4-3 uses a built-in genetic algorithm in finite element analysis software to adjust the wire diameter and enamel thickness of the coil winding, thereby increasing the inductor's self-resonant frequency.

[0013] Furthermore, step S5 also includes the following sub-steps: S5-1, the coil is wound using an automated winding device. The automated winding device has the functions of automated wire arrangement and control of the number of coil turns, wire diameter and tension, which can make the coils neatly arranged on the magnetic core and avoid crossing and overlapping. S5-2, during the winding process, a current sensor is used to monitor the current distribution in each coil in real time to achieve uniform current distribution; During the winding process, S5-3 uses thermocouples to monitor the temperature change of the coil in real time and determines the safe temperature range based on the insulating varnish. The insulating varnish includes Class B, Class F, and Class H insulating varnish. The safe temperature range of Class B insulating varnish is between 100°C and 120°C, the safe temperature range of Class F insulating varnish is between 120°C and 140°C, and the safe temperature range of Class H insulating varnish is between 140°C and 160°C.

[0014] Furthermore, step S6 also includes the following sub-steps: S6-1. Select the encapsulation material of the inductor according to the sealing performance index to reduce the influence of the external environment on the performance of the inductor. The sealing performance index includes water vapor transmission rate, oxygen transmission rate, chemical corrosion resistance, mechanical strength, electrical insulation performance and thermal stability. The encapsulation material includes epoxy resin, polyimide, polytetrafluoroethylene, silicone rubber and ceramic materials. S6-2 uses vacuum packaging technology to encapsulate the prepared inductor, reducing air residue during the packaging process; S6-3. Select a frequency range that covers the inductor's self-resonant frequency, use a network analyzer to scan, observe the inductor's impedance curve, and measure the self-resonant frequency, which is the frequency corresponding to the first resonant peak of the impedance curve.

[0015] Furthermore, a multi-coil inductor includes: The magnetic core is an EE-type magnetic core made of a high-permeability material, including silicon steel sheet, iron-based nanocrystalline alloy, amorphous alloy, permalloy, or iron-based soft magnetic composite material. The EE-type magnetic core is formed by a pressing process and includes two E-shaped parts. Each E-shaped part includes a central post and two side posts. The two E-shaped parts are aligned and combined together through the central post. An air gap is provided at the center of the magnetic core center column. The width of the air gap is 0.1mm to 1mm. The length of the air gap can adjust the magnetic circuit parameters and improve the self-resonant frequency of the inductor. For applications with operating frequencies above 1MHz, the coil windings are wound in parallel to reduce parasitic inductance and capacitance; for applications with operating frequencies below 1MHz, the coil windings are wound in layers to optimize space utilization. The wire diameter and enamel thickness of the coil windings are optimized through finite element analysis, which can improve the self-resonant frequency of the inductor. An insulating layer is provided between adjacent coil windings. The insulating layer is made of insulating materials, including polyimide film, polytetrafluoroethylene, polyester film, polypropylene film, silicone rubber, epoxy resin, polystyrene, or polycarbonate, to reduce electromagnetic interference between coils and interlayer capacitance.

[0016] The beneficial effects of the technical solution provided by this invention include at least the following: This invention features an EE-type magnetic core with an air gap at the center of the core's central column. By adjusting the length of the air gap, the self-resonant frequency of the inductor can be increased, effectively optimizing the magnetic circuit parameters and enabling the inductor to exhibit higher performance in applications with operating frequencies above 1MHz.

[0017] This invention optimizes the wire diameter and enamel thickness of the coil winding through finite element analysis, and selects a suitable winding method according to the operating frequency. This design can significantly improve the efficiency and stability of the inductor.

[0018] This invention uses a magnetic field segmentation method to divide the total magnetic flux into multiple equivalent magnetic fluxes, and accurately calculates each part of the magnetic flux and its influence on magnetic reluctance. By optimizing the magnetic field distribution, the magnetic properties of the magnetic core can be fully utilized, the efficiency of the magnetic circuit can be improved, and the overall performance of the inductor can be further enhanced.

[0019] This invention selects high-performance packaging materials and uses vacuum packaging technology to encapsulate the inductor. By reducing the amount of air residue during the packaging process, it can effectively isolate the external environment from the inductor's performance, improve the inductor's insulation performance and self-resonant frequency stability, and extend the inductor's service life. Attached Figure Description

[0020] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of a method provided in an embodiment of the present invention. Detailed Implementation

[0022] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a multi-coil inductor and its manufacturing process according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0025] The following description, in conjunction with the accompanying drawings, details a specific solution for a multi-coil inductor and its manufacturing process provided by the present invention.

[0026] Please see Figure 1 The diagram illustrates a process flow chart of a manufacturing process for a multi-coil inductor according to an embodiment of the present invention, the method comprising the following steps: Step S1: Select a permeability material to prepare an EE-type magnetic core, open an air gap at the center of the core's central column, and increase the inductor's self-resonant frequency by adjusting the length of the air gap; Step S1 further includes the following sub-steps: S1-1, Select magnetic permeability materials with a relative permeability of more than 10000 as magnetic core materials. Magnetic permeability materials include silicon steel sheets, iron-based nanocrystalline alloys, amorphous alloys, permalloys and iron-based soft magnetic composite materials. S1-2, the core material is cut and EE-type core is formed by pressing process. The EE-type core consists of two E-shaped parts. Each E-shaped part includes a central post and two side posts. The two E-shaped parts are aligned and combined together through the central post. S1-3, an air gap is machined at the center of the EE-type magnetic core center column to achieve symmetrical and uniform magnetic field distribution. The width of the air gap is 0.1mm to 1mm, and the length of the air gap satisfies the following formula: Where g is the length of the air gap. Let be the free permeability, and A be the cross-sectional area of ​​the magnetic core. The relative permeability of the core material. For the target self-resonant frequency, This is the initial self-resonant frequency.

[0027] It should be noted that the purpose of selecting materials with a relative permeability of over 10,000 is to improve the permeability of the magnetic core, thereby improving the performance of the inductor. Materials with high permeability can guide the magnetic field more effectively, reduce magnetic resistance, and increase the inductance and efficiency of the inductor.

[0028] Silicon steel sheet: relative permeability: 10000-20000. Silicon steel sheet is a commonly used soft magnetic material. By adding silicon to steel, iron loss is reduced. It has the characteristics of high permeability, low coercivity and low iron loss.

[0029] Iron-based nanocrystalline alloys: relative permeability: above 100,000. Nanocrystalline alloys are soft magnetic materials prepared by rapid solidification process. They have nanoscale grain size, high permeability, low coercivity and high saturation magnetic induction.

[0030] Amorphous alloys: Relative magnetic permeability: above 100,000. Amorphous alloys are metallic materials without a crystalline structure. They have excellent soft magnetic properties, high magnetic permeability, low coercivity and low iron loss. Due to their amorphous structure, they have good corrosion resistance and mechanical properties.

[0031] Permalloy: with a relative permeability of 10,000-100,000, permalloy is a soft magnetic material with high permeability. Its main components are nickel and iron, and it has high permeability, low coercivity and good soft magnetic properties.

[0032] Iron-based soft magnetic composite materials: with a relative permeability of 10,000-20,000, these are composite materials composed of soft magnetic powder and insulating binder. They have high permeability, good mechanical properties and processability, and can be manufactured into complex magnetic core shapes through processes such as injection molding.

[0033] Cutting process: High-precision cutting equipment (laser cutting or wire cutting) is used to cut the magnetic core material to ensure cutting accuracy and surface quality. The cut magnetic core material should have good flatness and dimensional accuracy to reduce errors in subsequent forming processes.

[0034] Pressing process: The pressing process shapes the core material into an EE-type core. The pressing process can ensure the dimensional accuracy and shape consistency of the core, and improve production efficiency and product quality.

[0035] Structural Design: The EE-type magnetic core consists of two E-shaped parts, each of which includes a central post and two side posts. This structural design helps to improve the magnetic flux utilization of the core and facilitates the arrangement of the windings. The two E-shaped parts are aligned and combined together through the central post to ensure the symmetry and uniformity of the core.

[0036] Machining: Use high-precision machining equipment (CNC milling machine or laser processing equipment) to open an air gap at the center of the EE type magnetic core center column. Machining should ensure the dimensional accuracy and surface quality of the air gap and avoid the influence of machining errors on the magnetic field distribution.

[0037] Location selection: An air gap is opened at the center of the magnetic core center column. The location selection of the air gap is crucial because it directly affects the distribution of the magnetic field and the symmetry of the magnetic circuit.

[0038] Air gap width: The width of the air gap is 0.1mm to 1mm. The selection of the air gap width needs to be balanced between optimizing the magnetic circuit parameters and reducing the magnetic resistance. An air gap that is too wide will lead to an increase in magnetic resistance and a decrease in inductance; an air gap that is too narrow will be difficult to process and control.

[0039] Air gap length: The length of the air gap is calculated using a formula. By adjusting the length of the air gap, the self-resonant frequency of the inductor can be optimized to meet design requirements. Adjusting the length of the air gap can change the magnetic reluctance of the magnetic circuit, thereby affecting the inductance and self-resonant frequency of the inductor.

[0040] Step S2: Design the number of turns, wire diameter, and winding method for each coil winding, and set an insulation layer between adjacent coil windings; Step S2 further includes the following sub-steps: S2-1, Design the number of turns for each coil winding. The specific calculation formula is as follows: Where N is the number of turns in each coil winding, L is the inductance, s is the magnetic path length, and A is the cross-sectional area of ​​the magnetic core. ρ is the permeability of the magnetic core; S2-2, Design the wire diameter for each coil winding. The specific calculation formula is as follows: Where J is the current density and d is the wire diameter. It is the maximum current density allowed by the material; S2-3, design the winding method of each coil winding. For applications with operating frequencies above 1MHz, parallel winding is adopted to reduce parasitic inductance and capacitance. For applications with operating frequencies below 1MHz, layered winding is adopted to optimize space utilization. S2-4, an insulating layer is set between adjacent coil windings using insulating materials to reduce electromagnetic interference and interlayer capacitance between coils. Insulating materials include polyimide film, polytetrafluoroethylene, polyester film, polypropylene film, silicone rubber, epoxy resin, polystyrene, and polycarbonate.

[0041] It should be noted that the number of turns directly affects the inductance of the inductor. By accurately calculating the number of turns, it can be ensured that the inductance of the inductor meets the design requirements. Using the turns calculation formula, the number of turns of each coil winding can be accurately calculated based on the required inductance, core parameters, and magnetic circuit length, ensuring that the performance of the inductor meets the design requirements.

[0042] The choice of wire diameter directly affects the current carrying capacity and losses of the coil. By accurately calculating the wire diameter, it can be ensured that the coil does not overheat under the working current and that the losses are minimized. Using the wire diameter calculation formula, a suitable wire diameter can be calculated based on the working current and the maximum current density of the material to ensure that the coil does not overheat under working conditions and at the same time reduce losses.

[0043] The choice of winding method directly affects the high-frequency performance and space utilization of inductors. Different winding methods are suitable for different operating frequencies and application scenarios. Parallel winding is suitable for applications with operating frequencies above 1MHz because it can reduce parasitic inductance and capacitance and improve the self-resonant frequency of the inductor. Layered winding is suitable for applications with operating frequencies below 1MHz because it can optimize space utilization and reduce the size of the inductor.

[0044] The addition of an insulating layer can reduce electromagnetic interference between coils and interlayer capacitance, thereby improving the performance and reliability of the inductor.

[0045] Polyimide film: It has high insulation properties and good mechanical strength, and is suitable for applications with operating frequencies above 1MHz.

[0046] Polytetrafluoroethylene (PTFE): It has excellent insulation properties and chemical stability, and is suitable for applications with high temperature and operating frequency above 1MHz.

[0047] Polyester film: It has good insulation properties and is cost-effective, making it suitable for general applications.

[0048] Polypropylene film: It has high insulation properties and low dielectric constant, and is suitable for applications with operating frequencies above 1MHz.

[0049] Silicone rubber: It has good insulation properties and elasticity, making it suitable for flexible applications.

[0050] Epoxy resin: It has high insulation properties and good mechanical strength, and is suitable for encapsulation and insulation layers.

[0051] Polystyrene: It has good insulation properties and is cost-effective, making it suitable for general applications.

[0052] Polycarbonate: It has high insulation properties and good mechanical strength, and is suitable for applications with operating frequencies above 1MHz.

[0053] Step S3: The total magnetic flux is divided into multiple equivalent magnetic fluxes using the magnetic field segmentation method, and the magnetic flux of each part and its influence on magnetic reluctance are calculated respectively. Step S3 further includes the following sub-steps: S3-1, the total magnetic flux is divided into n equivalent magnetic fluxes using the magnetic field segmentation method. The specific calculation formula is as follows: in, Let n be the total magnetic flux, and n be the number of magnetic flux segments. The equivalent magnetic flux after segmentation, where i is an index used to distinguish different parts of the magnetic core; S3-2, calculate the magnetic induction intensity of each equivalent magnetic flux in the center post, side post, and air gap of the magnetic core, respectively. The specific calculation formula is as follows: in, It is the magnetic flux density of the i-th part of the magnetic core. It is the cross-sectional area of ​​the i-th part of the magnetic core; S3-3, Based on the distribution of magnetic flux in each part, calculate its impact on magnetic reluctance. The specific calculation formula is as follows: Where s is the magnetic circuit length and A is the cross-sectional area of ​​the magnetic core. ρ is the permeability of the magnetic core.

[0054] It should be noted that the magnetic field segmentation method is a method used to analyze complex magnetic circuits. By dividing the total magnetic flux into multiple equivalent magnetic fluxes, the magnetic field distribution in different parts of the magnetic core and its influence on the magnetic circuit parameters can be analyzed more accurately. It is particularly suitable for multi-coil inductors because their magnetic core structure is complex, contains multiple parts, and has an uneven magnetic field distribution.

[0055] Total magnetic flux segmentation: The total magnetic flux is divided into n equivalent magnetic fluxes, each of which represents the magnetic flux of a specific part of the magnetic core. By segmenting the total magnetic flux into multiple equivalent magnetic fluxes, the magnetic field distribution of different parts of the magnetic core can be analyzed in more detail. This is particularly suitable for complex magnetic core structures, including EE-type magnetic cores of multi-coil inductors.

[0056] Calculation of magnetic flux density: By calculating the magnetic flux density of each equivalent magnetic flux in different parts of the magnetic core, we can more accurately understand the distribution of the magnetic field in the magnetic core. Magnetic flux density is represented by the symbol B and describes the magnetic flux per unit area. The unit is Tesla (T).

[0057] Calculation of magnetic reluctance: Calculating the effect of magnetic flux on magnetic reluctance in each part can assess the loss in the magnetic circuit, optimize the geometry and size of the magnetic core, and improve the efficiency and performance of the inductor.

[0058] Step S4: Optimize the wire diameter and enamel thickness of the coil winding through finite element analysis to improve the self-resonant frequency of the inductor; Step S4 further includes the following sub-steps: S4-1. A three-dimensional model of the inductor is established using finite element analysis software, and material properties are defined. The three-dimensional model includes the magnetic core, air gap, coil winding and insulation layer. Material properties include the permeability of the magnetic core, the conductivity of the coil, the dielectric constant of the coating and the loss factor. S4-2, the three-dimensional model of the inductor is meshed and refined to capture electromagnetic field characteristics, including the gradient change of magnetic field strength, the distribution of current density, and the propagation characteristics of electromagnetic field in different media. S4-3 uses a built-in genetic algorithm in finite element analysis software to adjust the wire diameter and enamel thickness of the coil winding, thereby increasing the inductor's self-resonant frequency.

[0059] It should be noted that finite element analysis (FEA) is a numerical simulation method used to solve complex electromagnetic field problems. Through finite element analysis, the electromagnetic performance of inductors can be accurately simulated, and the wire diameter and enamel thickness of the coil windings can be optimized, thereby improving the self-resonant frequency and overall performance of the inductor.

[0060] Wire diameter optimization: By adjusting the wire diameter, the DC resistance of the coil can be reduced and the efficiency of the inductor can be improved. A suitable wire diameter can reduce the skin effect and proximity effect at high frequencies and improve the self-resonant frequency.

[0061] Enamel thickness optimization: Enamel thickness affects the insulation performance and high-frequency loss of the coil. By optimizing the enamel thickness, losses at high frequencies can be reduced and the self-resonance frequency of the inductor can be increased.

[0062] Self-resonant frequency (SRF): Self-resonant frequency is one of the key performance indicators of inductors. It represents the frequency at which the inductor begins to resonate at high frequencies. By optimizing the wire diameter and enamel thickness of the coil winding, the self-resonant frequency can be significantly improved, enabling the inductor to perform better in high-frequency applications.

[0063] Establishing a 3D model: Establishing an accurate 3D model of the inductor is the foundation of finite element analysis. Through accurate modeling, the accuracy of the simulation results can be ensured. The 3D model should include the magnetic core, air gap, coil winding, and insulation layer, which together determine the electromagnetic performance of the inductor.

[0064] Permeability of magnetic core: The permeability of magnetic core material directly affects the performance of magnetic circuit.

[0065] Coil conductivity: The conductivity of the coil material affects the coil's DC resistance and high-frequency loss.

[0066] Dielectric constant and loss factor of the coating: The dielectric constant and loss factor of the coating affect the insulation performance and high-frequency loss of the coil.

[0067] Meshing is a key step in finite element analysis. By dividing the model into small mesh elements, the distribution of electromagnetic fields can be simulated more accurately.

[0068] Refining the mesh: Refining the mesh in key areas (the air gap of the magnetic core, the edge of the coil winding) can capture electromagnetic field characteristics, including gradient changes in magnetic field strength, distribution of current density, and propagation characteristics of electromagnetic fields in different media.

[0069] Gradient variation of magnetic field strength: In regions such as the magnetic core and air gap, the gradient variation of magnetic field strength is large, and the mesh needs to be refined to capture these variations.

[0070] Current density distribution: In high-frequency applications, the current density distribution has a significant impact on the performance of inductors and requires accurate simulation.

[0071] The propagation characteristics of electromagnetic fields in different media: Different media (magnetic core, air, insulating layer, etc.) have different propagation characteristics of electromagnetic fields, and these characteristics need to be simulated by refining the mesh.

[0072] Genetic algorithms are optimization algorithms that find the optimal solution by simulating the process of natural selection. In finite element analysis, genetic algorithms can be used to optimize the wire diameter and enamel thickness of coil windings.

[0073] The optimization process of a genetic algorithm includes: 1. Initialization: Generate a set of random combinations of wire diameter and paint thickness.

[0074] 2. Evaluation: The self-harmonic frequency for each set of parameters is calculated using finite element analysis.

[0075] 3. Selection: Select the parameter combination with the highest self-resonant frequency.

[0076] 4. Crossover and mutation: Generate new combinations of parameters through crossover and mutation operations.

[0077] 5. Iteration: Repeat the above process until the optimal solution is found.

[0078] The code that optimizes the wire diameter and enamel thickness of coil windings using a genetic algorithm includes: import random import numpy as np from deap import base, creator, tools, algorithms # Define the optimization problem creator.create("FitnessMax", base.Fitness, weights=(1.0,)) creator.create("Individual", list, fitness=creator.FitnessMax) # Initialize the genetic algorithm toolbox toolbox = base.Toolbox() toolbox.register("attr_float", random.uniform, 0.15, 0.20) # Wire diameter range 0.15 mm to 0.20 mm toolbox.register("attr_float2", random.uniform, 0.02, 0.03) # Paint thickness range 0.02 mm to 0.03 mm toolbox.register("individual", tools.initCycle, creator.Individual,(toolbox.attr_float, toolbox.attr_float2), n=1) toolbox.register("population", tools.initRepeat, list,toolbox.individual) # Define the evaluation function def evalSRF(individual): # This is a simplified evaluation function; in practice, the self-harmonic frequency needs to be calculated through finite element analysis. wire_diameter, insulation_thickness = individual # Assume the relationship between self-resonant frequency and wire diameter and paint thickness # A simplified formula is used here as an example; in practice, it should be replaced with the results of finite element analysis. SRF = 100000 / (wire_diameter + insulation_thickness) # Example formula return SRF, # Registering Genetic Algorithm Operation toolbox.register("evaluate", evalSRF) toolbox.register("mate", tools.cxBlend, alpha=0.5) toolbox.register("mutate", tools.mutGaussian, mu=0, sigma=0.01, indpb=0.2) toolbox.register("select", tools.selTournament, tournsize=3) # Running the genetic algorithm def main(): random.seed(42) pop = toolbox.population(n=50) hof = tools.HallOfFame(1) stats = tools.Statistics(lambda ind: ind.fitness.values) stats.register("avg", np.mean) stats.register("std", np.std) stats.register("min", np.min) stats.register("max", np.max) pop, log = algorithms.eaSimple(pop, toolbox, cxpb=0.5, mutpb=0.2,ngen=40, stats=stats, halloffame=hof, verbose=True) return pop, log, hof if __name__ == "__main__": pop, log, hof = main() best_individual = hof.items[0] print(f"Best individual: {best_individual}") print(f"Best SRF: {evalSRF(best_individual)[0]}") Step S5: The coil is wound using an automated winding device. During the winding process, the current distribution and temperature changes are monitored in real time to achieve a uniform and stable winding. Step S5 further includes the following sub-steps: S5-1 uses automated winding equipment for coil winding. The automated winding equipment has the functions of automated wire arrangement and control of the number of coil turns, wire diameter and tension, which can make the coils neatly arranged on the magnetic core and avoid crossing and overlapping. S5-2, during the winding process, a current sensor is used to monitor the current distribution in each coil in real time to achieve uniform current distribution; During the winding process, thermocouples are used to monitor the temperature change of the coil in real time. The safe temperature range is determined based on the insulating varnish. The insulating varnish includes Class B, Class F, and Class H insulating varnish. The safe temperature range of Class B insulating varnish is between 100°C and 120°C, that of Class F insulating varnish is between 120°C and 140°C, and that of Class H insulating varnish is between 140°C and 160°C.

[0079] It should be noted that the automated winding function: The automated winding equipment achieves automated winding through precise mechanical control and programming, ensuring that the coils are neatly arranged on the magnetic core, avoiding crossing and overlapping, and improving the uniformity and stability of the winding. This not only improves production efficiency but also reduces human error.

[0080] Controlling the number of coil turns, wire diameter, and tension: Automated winding equipment can precisely control the number of coil turns, wire diameter, and tension according to preset parameters, which not only improves the uniformity of the winding but also reduces electromagnetic interference and localized heating problems.

[0081] Use of current sensors: High-precision current sensors are used to monitor the current distribution in each coil in real time. If uneven current distribution is found, the current distribution can be optimized by adjusting the winding parameters (winding speed and tension). By monitoring the current distribution in real time, it is ensured that the current is evenly distributed in each coil, avoiding the problems of heat generation and electromagnetic interference caused by excessive local current density.

[0082] The importance of uniform current distribution: Uniform current distribution can reduce localized heating and improve the efficiency and reliability of inductors.

[0083] Thermocouple usage: Thermocouples are used to monitor the temperature changes of the coil in real time during the winding process. Depending on the type of insulating varnish used (Class B, F, or H), a corresponding safe temperature range is set. Different insulating varnishes have different heat resistance ratings. Selecting the appropriate insulating varnish and strictly controlling the temperature within the safe range can ensure the reliability and service life of the inductor.

[0084] The safe temperature range includes Class B insulating varnish: safe temperature range between 100°C and 120°C; Class F insulating varnish: safe temperature range between 120°C and 140°C; and Class H insulating varnish: safe temperature range between 140°C and 160°C.

[0085] Step S6: Select packaging material, use vacuum packaging technology to package the inductor, and measure the self-resonant frequency of the inductor using a network analyzer. Step S6 further includes the following sub-steps: S6-1. Select the encapsulation material of the inductor according to the sealing performance index to reduce the impact of the external environment on the inductor performance. The sealing performance index includes water vapor transmission rate, oxygen transmission rate, chemical corrosion resistance, mechanical strength, electrical insulation performance and thermal stability. The encapsulation materials include epoxy resin, polyimide, polytetrafluoroethylene, silicone rubber and ceramic materials. S6-2 uses vacuum packaging technology to encapsulate the prepared inductor, reducing air residue during the packaging process; S6-3. Select a frequency range that covers the inductor's self-resonant frequency, use a network analyzer to scan, observe the inductor's impedance curve, and measure the self-resonant frequency. The self-resonant frequency is the frequency corresponding to the first resonant peak of the impedance curve.

[0086] It should be noted that water vapor transmission rate refers to the amount of water vapor passing through a unit area per unit time under specific conditions. The encapsulation material should have a low water vapor transmission rate to prevent moisture from entering the inductor and affecting its performance. The water vapor transmission rate should be less than 1 g / m² / day.

[0087] Oxygen permeability: Oxygen permeability refers to the amount of oxygen passing through a unit area per unit time under specific conditions. The encapsulation material should have low oxygen permeability to prevent oxidation and corrosion. The oxygen permeability should be less than 1 cm³ / m² / day.

[0088] Chemical resistance: The encapsulation material should be able to resist the erosion of common chemicals (acids, alkalis, solvents). In standard chemical corrosion tests, the encapsulation material should exhibit good chemical resistance without significant degradation or damage.

[0089] Mechanical strength: The packaging material should have sufficient mechanical strength to withstand physical impacts during transportation and use. The tensile strength should be higher than 20 MPa, the elongation at break should be higher than 100%, and the hardness should be higher than 70 Shore D.

[0090] Electrical insulation performance: The encapsulation material should have good electrical insulation performance to prevent electrical breakdown and short circuit. The insulation resistance should be higher than 10^14 Ω·cm, and the withstand voltage should be higher than 10kV / mm.

[0091] Thermal stability: The encapsulation material should be able to maintain stable performance within the operating temperature range, without thermal degradation, with a heat distortion temperature higher than 150°C and a coefficient of thermal expansion lower than 10ppm / °C.

[0092] Epoxy resin: It has good mechanical strength and electrical insulation properties and is suitable for a variety of environmental conditions.

[0093] Polyimide: It has excellent high temperature resistance and electrical insulation properties, making it suitable for high temperature applications.

[0094] Polytetrafluoroethylene (PTFE): It has good chemical stability and electrical insulation properties, making it suitable for chemical environments.

[0095] Silicone rubber: It has good elasticity and electrical insulation properties and is suitable for flexible applications.

[0096] Ceramic materials: possess high hardness, high insulation properties, and good thermal stability, making them suitable for high-temperature and high-reliability applications.

[0097] Vacuum packaging technology: Packaging is performed in a vacuum environment to ensure that air is extracted during the packaging process, reducing the gas content inside the package, improving the sealing and reliability of the package, and further reducing the impact of the external environment on the performance of the inductor.

[0098] Selecting a frequency range: Based on the inductor's design parameters, select a frequency range that covers the inductor's self-resonant frequency to ensure accurate measurement of the self-resonant frequency. If the inductor's self-resonant frequency is expected to be around 1MHz, a frequency range of 0.1MHz to 10MHz can be selected.

[0099] Impedance curve scanning: Connect the inductor to the test port of the network analyzer, set the scanning frequency range and step size, record the impedance curve, and observe its frequency response.

[0100] Determine the self-resonant frequency: The self-resonant frequency is the frequency corresponding to the first resonant peak of the impedance curve. By analyzing the impedance curve, the position of the first resonant peak is found, and the self-resonant frequency is determined.

[0101] For a multi-coil inductor in this embodiment, it includes: The magnetic core adopts an EE-type magnetic core, which is made of high magnetic permeability material, including silicon steel sheet, iron-based nanocrystalline alloy, amorphous alloy, permalloy, or iron-based soft magnetic composite material. The EE-type magnetic core is formed by a pressing process and includes two E-shaped parts. Each E-shaped part includes a central post and two side posts. The two E-shaped parts are aligned and combined together through the central post. An air gap is provided at the center of the magnetic core center column. The width of the air gap is 0.1mm to 1mm. The length of the air gap can adjust the magnetic circuit parameters and improve the self-resonant frequency of the inductor. For applications with operating frequencies above 1MHz, the coil windings are wound in parallel to reduce parasitic inductance and capacitance; for applications with operating frequencies below 1MHz, the coil windings are wound in layers to optimize space utilization. The wire diameter and enamel thickness of the coil windings are optimized through finite element analysis, which can improve the self-resonant frequency of the inductor. An insulating layer is provided between adjacent coil windings. The insulating layer is made of insulating materials, including polyimide film, polytetrafluoroethylene, polyester film, polypropylene film, silicone rubber, epoxy resin, polystyrene or polycarbonate, to reduce electromagnetic interference between coils and interlayer capacitance.

[0102] It should be noted that the magnetic core material selection is as follows: the magnetic core uses high permeability materials, such as silicon steel sheets, iron-based nanocrystalline alloys, amorphous alloys, permalloy, or iron-based soft magnetic composite materials. These materials have high permeability, low loss, and good mechanical properties, and are suitable for high-frequency and high-power-density inductors.

[0103] Core structure design: The EE type core is formed by pressing and includes two E-shaped parts. Each E-shaped part includes a central post and two side posts. The two E-shaped parts are aligned and combined together through the central post. This structural design helps to improve the magnetic flux utilization of the core and facilitates the arrangement of the windings.

[0104] Air gap design: An air gap is provided at the center of the magnetic core center column. The width of the air gap is 0.1mm to 1mm. The length of the air gap can be calculated by formula to adjust the magnetic circuit parameters and improve the self-resonant frequency of the inductor. The design of the air gap is crucial for optimizing the performance of the inductor.

[0105] The coil winding methods include: for applications above 1MHz, parallel winding is used to reduce parasitic inductance and capacitance and improve the inductor's self-resonant frequency; for applications below 1MHz, layered winding is used to optimize space utilization and reduce the inductor's size.

[0106] Coil winding optimization design: The wire diameter and enamel thickness of the coil winding are optimized through finite element analysis to improve the self-resonant frequency of the inductor. This optimization design can reduce losses at high frequencies and improve the efficiency and performance of the inductor.

[0107] Insulation material selection: An insulation layer is provided between adjacent coil windings, using high-insulation-performance materials, including polyimide film, polytetrafluoroethylene, polyester film, polypropylene film, silicone rubber, epoxy resin, polystyrene, or polycarbonate. These materials have good insulation properties and mechanical strength, which can reduce electromagnetic interference between coils and interlayer capacitance.

[0108] Function of the insulation layer: The insulation layer effectively reduces electromagnetic interference between coils and interlayer capacitance, improving the performance and reliability of the inductor. This is especially important for high-frequency applications, as electromagnetic interference and parasitic capacitance at high frequencies can significantly impact inductor performance.

[0109] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A manufacturing process for a multi-coil inductor, characterized in that, Includes the following steps: Step S1: Select a permeability material to prepare an EE-type magnetic core, open an air gap at the center of the core's central column, and increase the inductor's self-resonant frequency by adjusting the length of the air gap; Step S2: Design the number of turns, wire diameter, and winding method for each coil winding, and set an insulation layer between adjacent coil windings; Step S3: The total magnetic flux is divided into multiple equivalent magnetic fluxes using the magnetic field segmentation method, and the magnetic flux of each part and its influence on magnetic reluctance are calculated respectively. Step S4: Optimize the wire diameter and enamel thickness of the coil winding through finite element analysis to improve the self-resonant frequency of the inductor; Step S5: The coil is wound using an automated winding device. During the winding process, the current distribution and temperature changes are monitored in real time to achieve a uniform and stable winding. Step S6: Select packaging material, use vacuum packaging technology to package the inductor, and measure the self-resonant frequency of the inductor using a network analyzer.

2. The manufacturing process of a multi-coil inductor according to claim 1, characterized in that: Step S1 further includes the following sub-steps: S1-1, Select a magnetic permeability material with a relative permeability of 10000 or higher as the core material. The magnetic permeability material includes silicon steel sheet, iron-based nanocrystalline alloy, amorphous alloy, permalloy and iron-based soft magnetic composite material. S1-2, the core material is cut and EE-shaped core is formed by pressing process. The EE-shaped core is composed of two E-shaped parts. Each E-shaped part includes a central post and two side posts. The two E-shaped parts are aligned and combined together through the central post. S1-3, An air gap is machined at the center of the central column of the EE-type magnetic core to achieve symmetrical and uniform magnetic field distribution. The width of the air gap is 0.1mm to 1mm, and the length of the air gap satisfies the following formula: Where g is the length of the air gap. Let be the free permeability, and A be the cross-sectional area of ​​the magnetic core. The relative permeability of the core material. For the target self-resonant frequency, This is the initial self-resonant frequency.

3. The manufacturing process of a multi-coil inductor according to claim 1, characterized in that: Step S2 further includes the following sub-steps: S2-1, Design the number of turns for each coil winding. The specific calculation formula is as follows: Where N is the number of turns in each coil winding, L is the inductance, s is the magnetic path length, and A is the cross-sectional area of ​​the magnetic core. ρ is the permeability of the magnetic core; S2-2, Design the wire diameter for each coil winding. The specific calculation formula is as follows: Where J is the current density and d is the wire diameter. It is the maximum current density allowed by the material; S2-3, design the winding method of each coil winding. For applications with operating frequencies above 1MHz, parallel winding is adopted to reduce parasitic inductance and capacitance. For applications with operating frequencies below 1MHz, layered winding is adopted to optimize space utilization. S2-4, An insulating layer is set between adjacent coil windings using insulating materials to reduce electromagnetic interference and interlayer capacitance between coils. The insulating materials include polyimide film, polytetrafluoroethylene, polyester film, polypropylene film, silicone rubber, epoxy resin, polystyrene, and polycarbonate.

4. The manufacturing process of a multi-coil inductor according to claim 1, characterized in that: Step S3 further includes the following sub-steps: S3-1, the total magnetic flux is divided into n equivalent magnetic fluxes using the magnetic field segmentation method. The specific calculation formula is as follows: in, Let n be the total magnetic flux, and n be the number of magnetic flux segments. The equivalent magnetic flux after segmentation, where i is an index used to distinguish different parts of the magnetic core; S3-2, calculate the magnetic induction intensity of each equivalent magnetic flux in the center post, side post, and air gap of the magnetic core, respectively. The specific calculation formula is as follows: in, It is the magnetic flux density of the i-th part of the magnetic core. It is the cross-sectional area of ​​the i-th part of the magnetic core; S3-3, Based on the distribution of magnetic flux in each part, calculate its impact on magnetic reluctance. The specific calculation formula is as follows: Where s is the magnetic circuit length and A is the cross-sectional area of ​​the magnetic core. ρ is the permeability of the magnetic core.

5. The manufacturing process of a multi-coil inductor according to claim 1, characterized in that: Step S4 further includes the following sub-steps: S4-1. A three-dimensional model of the inductor is established using finite element analysis software, and material properties are defined. The three-dimensional model includes a magnetic core, an air gap, a coil winding, and an insulating layer. The material properties include the permeability of the magnetic core, the conductivity of the coil, the dielectric constant of the coating, and the loss factor. S4-2, The three-dimensional model of the inductor is meshed and refined to capture electromagnetic field characteristics, including the gradient change of magnetic field strength, the distribution of current density, and the propagation characteristics of electromagnetic field in different media. S4-3 uses a built-in genetic algorithm in finite element analysis software to adjust the wire diameter and enamel thickness of the coil winding, thereby increasing the inductor's self-resonant frequency.

6. The manufacturing process of a multi-coil inductor according to claim 1, characterized in that: Step S5 further includes the following sub-steps: S5-1, the coil is wound using an automated winding device. The automated winding device has the functions of automated wire arrangement and control of the number of coil turns, wire diameter and tension, which can make the coils neatly arranged on the magnetic core and avoid crossing and overlapping. S5-2, during the winding process, a current sensor is used to monitor the current distribution in each coil in real time to achieve uniform current distribution; During the winding process, S5-3 uses thermocouples to monitor the temperature change of the coil in real time and determines the safe temperature range based on the insulating varnish. The insulating varnish includes Class B, Class F, and Class H insulating varnish. The safe temperature range of Class B insulating varnish is between 100°C and 120°C, the safe temperature range of Class F insulating varnish is between 120°C and 140°C, and the safe temperature range of Class H insulating varnish is between 140°C and 160°C.

7. The manufacturing process of a multi-coil inductor according to claim 1, characterized in that: Step S6 further includes the following sub-steps: S6-1, Select the encapsulation material of the inductor according to the sealing performance index to reduce the influence of the external environment on the performance of the inductor. The sealing performance index includes water vapor transmission rate, oxygen transmission rate, chemical corrosion resistance, mechanical strength, electrical insulation performance and thermal stability. The encapsulation material includes epoxy resin, polyimide, polytetrafluoroethylene, silicone rubber and ceramic materials. S6-2 uses vacuum packaging technology to encapsulate the prepared inductor, reducing air residue during the packaging process; S6-3. Select a frequency range that covers the inductor's self-resonant frequency, use a network analyzer to scan, observe the inductor's impedance curve, and measure the self-resonant frequency, which is the frequency corresponding to the first resonant peak of the impedance curve.

8. A multi-coil inductor, characterized in that, include: The magnetic core is an EE-type magnetic core made of a high-permeability material, including silicon steel sheet, iron-based nanocrystalline alloy, amorphous alloy, permalloy, or iron-based soft magnetic composite material. The EE-type magnetic core is formed by a pressing process and includes two E-shaped parts. Each E-shaped part includes a central post and two side posts. The two E-shaped parts are aligned and combined together through the central post. An air gap is provided at the center of the magnetic core center column. The width of the air gap is 0.1mm to 1mm. The length of the air gap can adjust the magnetic circuit parameters and improve the self-resonant frequency of the inductor. For applications with operating frequencies above 1MHz, the coil windings are wound in parallel to reduce parasitic inductance and capacitance; for applications with operating frequencies below 1MHz, the coil windings are wound in layers to optimize space utilization. The wire diameter and enamel thickness of the coil windings are optimized through finite element analysis, which can improve the self-resonant frequency of the inductor. An insulating layer is provided between adjacent coil windings. The insulating layer is made of insulating materials, including polyimide film, polytetrafluoroethylene, polyester film, polypropylene film, silicone rubber, epoxy resin, polystyrene, or polycarbonate, to reduce electromagnetic interference between coils and interlayer capacitance.

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