An inductive power taking efficiency improving method based on magnetic coupling

Abstract

The application provides an inductive power taking efficiency improving method based on magnetic coupling, and particularly relates to an inductive power taking efficiency improving method of a variable mechanical performance magnetic coupling agent based on an environment characteristic matching mechanism; the application determines mechanical indexes of a magnetic coupling agent paste for different environment empirical values by designing a tapering degree initial value estimation formula, adjusts a single component ratio, adjusts the hardness, temperature stability and other performances of the coupling agent paste without affecting other performances to configure a preliminary magnetic coupling agent, and then compensates mechanical characteristics after error correction of effect test of the magnetic coupling agent to obtain a final paste tapering degree to configure a final coupling agent paste, so that the magnetic coupling performance of an inductive power taking device is optimized, and the inductive power taking efficiency is improved; the application is an environment characteristic matching effect evaluation method based on a fiber material science characterization method, feeds back and compensates the component ratio of the magnetic coupling agent paste, and realizes inductive power taking efficiency improvement in a specific application environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power line induction power taking, in particular to an induction power taking efficiency improving method based on magnetic coupling. BACKGROUND

[0002] With the development of smart grid, the safe and stable operation of power system is particularly important, and online monitoring equipment is widely used in high-voltage power transmission cables. At present, the power supply modes of commonly used online monitoring equipment mainly include: battery, solar energy, laser, capacitive voltage division online power taking and induction power taking, etc. Induction power taking adopts non-contact induction power taking technology, has the advantages of high safety, low cost, small size and wide application range compared with other methods, and is widely used.

[0003] However, the induction power taking device has the problems of poor working environment, difficult maintenance, poor magnetic coupling, high magnetic resistance and low induction power taking efficiency. At the same time, the induction power taking device has installation and removal requirements, and cannot use fixed magnetic coupling method. At present, in order to solve the problem of induction power taking device power taking efficiency degradation in high-power application occasions, there are three directions of optimizing materials, optimizing topology structure and magnetic coupling method optimization. The optimization of materials direction is to select nanocrystalline material core and adopt double core parallel working mode. When the current is small, the energy is transmitted through the air gapless core. As the current increases, the air gapless core enters saturation, and the energy is transmitted through the air gap core. However, the energy transmission is unstable. The optimization of topology structure direction is to improve the magnetic circuit topology structure method, which reduces the starting current, but increases the line burden and is prone to switching failure. Or a set of differential coils is added on the magnetic core, which is controlled to be connected and disconnected to adapt to different current sizes, but the control is complex and unstable. The magnetic circuit coupling method optimization is to use magnetic conductive glue. Although this method can improve the magnetic circuit coupling performance and increase the chemical stability, the disassembly convenience is reduced after solidification, which is not conducive to the application of induction power taking. The coupling agent based on paste cannot meet the mechanical performance requirements of different application environments after preparation.

[0004] Therefore, the above-mentioned traditional methods cannot achieve the best effect in solving the problem of power taking efficiency degradation of high-power induction power taking device caused by different environments. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings and deficiencies of the prior art, and to provide an induction power taking efficiency improving method based on magnetic coupling. The induction power taking efficiency improving method is divided into four steps: environment and magnetic circuit characteristic determination and experience parameter setting, magnetic coupling agent preparation and mechanical property adjustment, magnetic coupling agent trial and effect evaluation, and coupling agent mechanical property compensation. The specific contents are as follows:

[0006] Step 1. Environment and magnetic circuit characteristic determination and experience parameter setting

[0007] Different installation environment characteristics will have different impacts on magnetic circuit coupling and place different demands on magnetic coupling agents. Harsh external environments require the magnetic coupling agent paste to have higher mechanical and temperature stability, but this may reduce the coupling agent's contact efficiency and lead to increased magnetic resistance. Therefore, it is necessary to find a suitable performance value range to obtain the optimal coordination ratio.

[0008] First, cone penetration is used to characterize the mechanical strength of the paste, and a formula for estimating the initial value of cone penetration is established, including the magnetic permeability of the core, saturation magnetic flux density, core cross-sectional area, ambient temperature, ambient humidity, and vibration intensity:

[0009]

[0010] Where Z is the cone penetration, The cone penetration empirical parameter is usually 70-90. (According to the industry standard for magnetic coupling agent paste, the corresponding cone penetration empirical parameter can be directly found and selected. For example, the brand classification of grease is usually based on the cone penetration range, so the cone penetration empirical parameter can be directly selected according to the brand; this range is only a reference range.) is the adjustment coefficient, is the core permeability, S is the core cross-sectional area, t is the ambient temperature, R is the ambient humidity, A is the vibration intensity, and T is the saturation flux density. The core permeability and saturation flux density of commonly used materials are as follows: Figure 1 shown.

[0011] Step 2. Preparation of magnetic coupling agent and adjustment of mechanical properties

[0012] The coupling agent can use silicone-based grease as the base oil, and the magnetic conductive material can be ceramic ferrite (mainly composed of iron oxide, nickel oxide, and zinc oxide, prepared through a ceramic process), and ultra-short fiber fillers for adjusting mechanical properties (such as glass fiber and carbon nanotubes). The cone penetration is calculated according to the cone penetration initial value estimation formula described in step 1, and the specific mechanical property adjustment filler ratio is determined experimentally using the dichotomy method. Finally, a preliminary magnetic coupling agent is prepared through vacuum planetary dispersion.

[0013] Step 3. Trial and effect evaluation of magnetic coupling agent

[0014] Apply the preliminary magnetic coupling agent prepared in step 2 to the magnetic circuit contact surface of the induction power device, install the device, and perform accelerated aging operation based on the actual environment; the magnetic coupling agent application position is as follows: Figure 2 shown.

[0015] The efficiency of inductive power extraction is tested from the perspective of power detection, and the line current and output voltage of the inductive power extraction device, as well as the current, voltage and power at the load end are detected.

[0016] The degradation rate of the magnetic circuit contact surface is detected from the perspective of fiber materials, such as using polarizing microscopy, infrared spectroscopy, Raman spectroscopy and other characterization methods.

[0017] After all tests, the effects are comprehensively evaluated to obtain the performance error , ranging from 0 to 1.

[0018] Step 4. Compensation of couplant mechanical properties

[0019] Based on the measured performance error and compensation for mechanical properties, the final paste penetration calculation formula is obtained:

[0020]

[0021] in To adjust the range (by accurately identifying the error source, the α parameter can be adjusted more specifically, thereby more effectively compensating for performance errors. Error sources include the accuracy limitations of measurement equipment, changes in environmental conditions, fluctuations in material properties, etc.; set The maximum and minimum adjustment values ​​and the adjustment step size are used to determine whether the adjustment is effective by observing the improvement in cone penetration performance after adjusting the α parameter. If the performance is significantly improved and the stability is good, the adjustment direction is correct; if the performance improvement is not obvious or even decreases, there may be a problem with the adjustment strategy and the direction or method needs to be adjusted. To compensate for the posterior cone penetration.

[0022] Then, the dichotomy method is used to experimentally configure a coupling agent paste with the final cone penetration, determine the corresponding mechanical filler ratio, and finally determine the coupling agent formula to achieve an improvement in the inductive power extraction efficiency based on a specific environment.

[0023] The beneficial effects of the present invention are as follows: Based on the characteristics of the environment (such as temperature, humidity, vibration, etc.) and combined with the magnetic circuit characteristics (such as the magnetic core permeability and saturation magnetic flux density), the present invention proposes a formula for estimating the initial value of cone penetration to accurately coordinate the mechanical performance indicators of the magnetic coupling agent. By adjusting the proportion of a single component, the hardness, temperature stability and other properties of the coupling agent paste are adjusted without affecting other properties to configure a preliminary magnetic coupling agent. Then, by performing error correction on the effect test of the magnetic coupling agent, the final paste cone penetration is obtained after compensating for the mechanical properties to configure the final coupling agent paste, so that the magnetic coupling performance of the induction power supply device is optimized, the adaptability of the magnetic coupling agent in different environments is ensured, and the performance degradation caused by the mismatch of the environment or magnetic circuit characteristics is effectively avoided, laying a solid foundation for improving the efficiency of induction power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings required by the embodiments or the prior art description will be briefly introduced as follows. Obviously, the accompanying drawings in the following description only represent some embodiments of the present application, and for those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0025] Figure 1 For the characteristics of commonly used magnetic core materials;

[0026] Figure 2 For the schematic diagram of the smearing position of the magnetic circuit contact surface of the inductive power taking device (magnetic core open air gap);

[0027] Figure 3 For the schematic diagram of the inductive power taking principle;

[0028] Figure 4 For the schematic diagram of the cross section of the magnetic core;

[0029] Figure 5 For the flowchart of the present application;

[0030] Figure 6 For the relationship between the tapering degree and the content of graphene;

[0031] Figure 7 For the relationship between the tapering degree and the content of the compounded graphite powder. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application will be further described in detail below with examples and drawings.

[0033] The inductive power taking efficiency improving method described in the present application is divided into four steps: environment and magnetic circuit characteristic determination and experience parameter setting, magnetic force coupling agent preparation and mechanical property adjustment, magnetic force coupling agent trial and effect evaluation, coupling agent mechanical property compensation; the specific contents are as follows:

[0034] Step 1. Environment and magnetic circuit characteristic determination and experience parameter setting

[0035] Different installation environment characteristics will have different effects on the magnetic circuit coupling, and different requirements for the magnetic force coupling agent; the harsh external environment requires the magnetic force coupling agent paste to have higher mechanical stability and temperature stability, but this may reduce the coupling agent contact efficiency, resulting in the rise of magnetic resistance, so it is necessary to find the appropriate performance value range to obtain the optimal coordination ratio.

[0036] Firstly, the tapering degree is used to represent the mechanical strength of the paste, and an initial value estimation formula of the tapering degree including the magnetic core permeability, the saturation magnetic flux density, the cross-sectional area of the magnetic core, the environment temperature, the environment humidity, and the vibration intensity is established:

[0037]

[0038] wherein Z is the taper, is the taper empirical parameter, usually taken as 70-90, is the adjustment coefficient, is the magnetic core permeability, S is the magnetic core cross-sectional area, t is the ambient temperature, R is the ambient humidity, A is the vibration intensity, T is the saturation magnetic flux density, wherein the commonly used material magnetic core permeability, saturation magnetic flux density are as shown in Figure 1 .

[0039] Step 2. Preparation of magnetic coupling agent and adjustment of mechanical properties

[0040] The coupling agent can use silicon-based grease as the base oil, the magnetic material is ceramic ferrite (mainly composed of iron oxide, nickel oxide, zinc oxide, prepared by ceramic process), ultra-short fiber type mechanical performance adjusting filler (such as glass fiber, carbon nanotube, etc.), the taper is calculated according to the initial value estimation formula of the taper described in step 1, and the specific mechanical performance adjusting filler ratio is determined through experiment using the bisection method, and finally the preliminary magnetic coupling agent is prepared through vacuum planetary dispersion.

[0041] Step 3. Trial and effect evaluation of magnetic coupling agent

[0042] The preliminary magnetic coupling agent prepared in step 2 is applied to the magnetic circuit contact surface of the inductive power taking device, and the equipment is installed, and the actual environment is referred to for accelerated aging operation; the magnetic coupling agent application position is as shown in Figure 2 .

[0043] From the perspective of power detection, the inductive power taking efficiency is detected, and the line current, output voltage of the inductive power taking device, current, voltage and power at the load end are detected.

[0044] From the perspective of fiber material, the degradation speed of the magnetic circuit contact surface is detected, such as using polarized light microscope, infrared spectrum, Raman spectrum and other characterization means.

[0045] After all the detection, the performance error is obtained by comprehensive evaluation of the effect , ranging from 0 to 1.

[0046] Step 4. Mechanical property compensation of coupling agent

[0047] Based on the measured performance error, the mechanical properties are compensated, and the final paste taper calculation formula is obtained:

[0048]

[0049] wherein Adjusting range (by accurately identifying the source of error, the α parameter can be more targeted to adjust, so as to more effectively compensate for performance errors. Error sources such as precision limitations of measuring equipment, changes in environmental conditions, fluctuations in material properties, etc.; set the maximum adjustment value, the minimum adjustment value and the adjustment step of α, and judge whether the adjustment is effective by observing the improvement of the cone-in performance after adjusting the α parameter. If the performance is significantly improved and the stability is good, it means that the adjustment direction is correct; if the performance improvement is not obvious or even decreases, it means that the adjustment strategy may have problems, and the direction or method needs to be adjusted), To compensate for the cone-in.

[0050] Then use the bisection method to configure the coupling agent paste with the final cone-in by experiment, determine the corresponding mechanical filler ratio, and finally determine the coupling agent formula to achieve the efficiency improvement of inductive power taking based on specific environment.

[0051] Embodiment

[0052] 1. Cone-in test

[0053] The cone-in of the magnetic coupling agent mainly reflects the softness and hardness, and the cone-in is the depth of the cone body falling into the sample at 25℃, the cone assembly is released from the cone-in meter, the cone body falls for 5 seconds, and the depth of the cone body falling is measured. The cone-in of the magnetic coupling agent in the non-working state (25℃, 1 / 4 cone body and cone rod assembly, falling for 5 seconds, and recording the depth of the cone body falling) is usually between 70 and 90. Referring to the data in Table 1, five kinds of magnetic coupling agents with different concentrations of ceramic ferrite are prepared, and other components are silicon-based grease and ultra-short fiber mechanical performance adjusting filler, the proportion of which is determined by bisection method. The specific mechanical performance adjusting filler ratio is determined, and the cone-in performance test is conducted on the five kinds of magnetic coupling agents.

[0054] Table 1 Relationship between cone-in and ceramic ferrite content

[0055]

[0056] Through testing, the cone-in of the magnetic coupling agent presents a linear decreasing trend with the increase of the ceramic ferrite content. The cone-in of the magnetic coupling agent with 77% and 78% ceramic ferrite content reaches 95.4 and 91.5 respectively, which exceeds the actual working requirement and cannot meet the use requirement. Because the cone-in of the magnetic coupling agent is too large, the overall state of the grease is low in viscosity, and it is easy to flow away in the actual use environment, thereby damaging the quality of electrical connection.

[0057] Referring to the data in Table 2, five kinds of magnetic coupling agents with different concentrations of graphene are prepared, and the cone-in performance test is conducted on the five kinds of magnetic coupling agents.

[0058] Table 2 Relationship between cone-in and graphene content

[0059]

[0060] Figure 6 The following graph shows the relationship between cone penetration (0.1mm) and graphene content (wt%). The cone penetration of the magnetic coupling agent decreases with increasing graphene content. When 3% graphene is added, the cone penetration reaches 97.8, which is significantly too high to meet engineering requirements. When the graphene content reaches 5%, the reduction begins to slow, eventually stabilizing. As the graphene content continues to decrease, the cone penetration of the magnetic coupling agent decreases from 97.8 to 71.4, a drop of 26.4 cone penetrations. This decrease is largely due to the structure of graphene itself. Graphene has a large specific surface area and a thickness of only 1.5nm. This nanoscale structural feature means that even a slight increase in graphene content can cause changes in the colloidal stability of the magnetic coupling agent.

[0061] The above tests examined the effects of adding either ceramic ferrite or graphene alone on the penetration of the magnetic coupling agent. It was found that increasing the conductive filler content resulted in a gradual decrease in penetration. To verify the effect of graphene on penetration, a formula was formulated to incorporate 1% graphene and mix it with ceramic ferrite to create a conductive filler for the magnetic coupling agent. The penetration of the magnetic coupling agent was observed as the overall filler content varied, as shown in Table 3.

[0062] Table 3 Relationship between cone penetration and compound graphene powder content

[0063]

[0064] Figure 7 The following graph shows the relationship between cone penetration (0.1mm) and compounded graphene powder content (wt%). The study found that the cone penetration of the magnetic coupling agent gradually decreases with increasing graphene powder content. At conductive filler concentrations of 69% and 70%, the cone penetrations of the magnetic coupling agent are 95.7 and 91.6, respectively. This results in a decrease in viscosity, making it unsuitable for practical engineering needs. Further increases in conductive filler content lead to a slower decrease in the viscosity of the magnetic coupling agent. At 73% filler content, the cone penetration reaches 82.7, a decrease of 13 cone penetrations, before eventually leveling off.

[0065] The above analysis provides a horizontal data analysis of the cone penetration of the magnetic coupling agents described above with varying filler contents. To further analyze the variations in cone penetration for the three types of magnetic coupling agents with varying filler contents and to explore the causes of these differences, a longitudinal comparative analysis of the cone penetration of these three magnetic coupling agents is conducted based on the data in Table 4. Data sets I, II, III, IV, and V represent the five filler concentrations (wt%) for all fillers, from groups 1 to 5, respectively.

[0066] Table 4 Comparison of cone penetration data of five different filler contents (0.1 mm)

[0067]

[0068] It is found that the cone penetration of the three types of magnetic coupling agents decreases with the increase of the filler content. Among them, the cone penetration of the graphene magnetic coupling agent decreases most obviously, from 97.8 to 71.4, with a decrease of 26.4. The decrease of the cone penetration of the ceramic ferrite and the compounded graphene type magnetic coupling agents is not much different, being 14.9 and 13 respectively. The overall decrease of the cone penetration is: graphene magnetic coupling agent > ceramic ferrite magnetic coupling agent > compounded graphene magnetic coupling agent.

[0069] Under the same conditions of the thickening agent and the silicone oil base, the main factor affecting the size of the cone penetration is the particle size of the filler. According to the data in Table 4, the smaller the particle size of the filler and the larger the specific surface area, the more the decrease of the cone penetration of the magnetic coupling agent prepared by using 2 μm ceramic ferrite, nano graphene and compounded graphene as the filler. It can be seen that the particle size and specific surface area of the filler material have a great influence on the change trend of the cone penetration. If the cone penetration is too large (greater than 90), the viscosity of the oil is low, and in the actual use environment, it is easy to flow out in the electric contact area, and the high temperature resistance performance will be greatly reduced, so that the magnetic coupling agent loses its effect. If the state of the magnetic coupling agent is too hard (less than 70), it is easy to bubble and dry in the actual application process, which can not completely contact the electric contact area, increase the contact resistance and damage the quality of the electric connection.

[0070] 2. Power test

[0071] The current sensor device based on inductive power taking is used for power test. The magnetic core material, magnetic core size, magnetic core parameters and the like of the current sensor are known, and the inductive power taking efficiency of the current sensor is optimized by using the method. The power test is carried out by changing the output voltage, and when the output voltage reaches 1000 V, the maximum available power at the load end is 138.74 W. It can be proved that the stability and efficiency of various inductive power taking devices on the power transmission line can be improved by this method.

[0072]

[0073] In summary, the beneficial effects of the present application are significant and multi-dimensional, mainly in the following aspects:

[0074] By analyzing the characteristics of different installation environments, such as temperature, humidity, vibration, etc., and combining the characteristics of the magnetic circuit, such as the magnetic permeability of the magnetic core and the saturation magnetic flux density, the application proposes an initial value estimation method for the taper degree, which can accurately set the mechanical performance indicators of the magnetic coupling agent. This step ensures the adaptability of the magnetic coupling agent in different environments and effectively avoids performance degradation caused by environmental or magnetic circuit characteristics mismatch, laying a solid foundation for improving the efficiency of inductive power supply.

[0075] During the preparation of the magnetic coupling agent, by adjusting the proportion of single components, the hardness and temperature stability of the paste body are adjusted in a wide range without compromising other key performance. This flexibility not only meets the special needs of different application environments, but also optimizes the overall performance of the coupling agent, reduces the magnetic circuit loss, and improves the energy transmission efficiency.

[0076] The application introduces an effect evaluation method based on fiber material characterization methods and power detection, which comprehensively evaluates the performance of the magnetic coupling agent and its impact on the efficiency of inductive power supply through accelerated aging operation in actual environment and more intuitive power detection methods. This scientific evaluation not only ensures the accuracy and reliability of the evaluation results, but also provides strong support for subsequent performance optimization.

[0077] For performance errors in the evaluation results, the application proposes a mechanical property compensation mechanism, which adjusts the parameters in the taper degree formula to achieve accurate compensation of the coupling agent performance. Combined with the bisection method experiment configuration, the optimal coupling agent formula is finally determined. This process not only improves the efficiency of inductive power supply, but also ensures the stability and reliability of the coupling agent in long-term use, providing strong support for the application of inductive power supply technology.

[0078] The above disclosure is only the preferred embodiment of the application, and of course cannot limit the scope of the application. Therefore, equivalent changes made in accordance with the claims of the application are still within the scope of the application.

Claims

1. A method for improving the efficiency of inductive power extraction based on magnetic coupling, characterized in that: The following steps are involved: S1. Determination of environmental and magnetic circuit characteristics and empirical parameter setting: Use cone penetration to characterize the mechanical strength of the magnetic coupling agent paste. Establish an initial cone penetration value estimation formula that includes core magnetic permeability, saturation magnetic flux density, core cross-sectional area, ambient temperature, ambient humidity, and vibration intensity: Where Z is the cone penetration; is the empirical parameter of cone penetration, with a value range of 60~80; is the adjustment factor; is the core permeability; S is the core cross-sectional area; t is the ambient temperature; R is the ambient humidity; A is the vibration intensity; T is the saturation magnetic flux density; S2. Preparation of magnetic coupling agent and adjustment of mechanical properties: Calculate the cone penetration according to the initial cone penetration estimation formula described in S1. Select and adjust the raw materials and proportions of the magnetic coupling agent to meet the estimated cone penetration to prepare a preliminary magnetic coupling agent. S3. Trial and evaluation of magnetic coupling agent: Apply the preliminary magnetic coupling agent prepared in S2 to the magnetic circuit contact surface of the induction power device. Install the device and perform accelerated aging in accordance with actual conditions. Test the induction power efficiency and the rate of deterioration of the magnetic circuit contact surface. After testing, conduct a comprehensive evaluation of the results to obtain a performance error, ∆e, ranging from 0 to 1. S4. Compensation of mechanical properties of coupling agent: Based on the performance error ∆e measured in S3, the mechanical properties are compensated to obtain the final paste penetration. , configure the final coupling agent paste according to the final paste cone penetration Z2, Among them, Z2 is the final cone penetration of the coupling agent paste after compensation, To adjust the range.

2. The method for improving the efficiency of inductive power extraction based on magnetic coupling according to claim 1, characterized in that: In step S2, the mechanical properties of each raw material are determined experimentally using a dichotomy method and the filler ratio is adjusted, and the magnetic coupling agent is prepared by vacuum planetary dispersion.

3. The method for improving the efficiency of inductive power extraction based on magnetic coupling according to claim 1, characterized in that: In step S2, the base oil of the coupling agent includes silicone-based grease, and the magnetic conductive material includes ceramic ferrite and ultra-short fibers.

4. The method for improving the efficiency of inductive power extraction based on magnetic coupling according to claim 1, characterized in that: In step S3, the efficiency of the inductive power extraction is detected from the perspective of power detection, including detecting the line current and the output voltage of the inductive power extraction device, and the current, voltage, and power at the load end.

5. The method for improving the efficiency of inductive power extraction based on magnetic coupling according to claim 1, characterized in that: In step S3, the degradation rate of the magnetic circuit contact surface is detected from the perspective of fiber material, including the use of polarizing microscope, infrared spectroscopy, and Raman spectroscopy characterization methods.

6. The method for improving the efficiency of inductive power extraction based on magnetic coupling according to claim 1, characterized in that: In step S4, according to the final paste penetration Z2, the coupling agent paste is configured experimentally using the dichotomy method to determine the corresponding mechanical filler ratio and obtain the final coupling agent formula to achieve an improvement in the inductive power extraction efficiency based on a specific environment.

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