Inductive power taking efficiency improving method based on magnetic coupling

Abstract

The invention provides an induction electricity taking efficiency improving method based on magnetic coupling, and particularly relates to an induction electricity taking efficiency improving method of a variable mechanical property magnetic coupling agent based on an environment characteristic matching mechanism. According to the method, a penetration initial value estimation formula is designed, mechanical indexes of the magnetic coupling agent paste are determined according to different environmental empirical values, the hardness, temperature stability and other properties of the coupling agent paste are adjusted by adjusting the proportion of a single component under the condition that other properties are not affected, and the initial magnetic coupling agent is prepared; error correction is carried out through effect testing of the magnetic coupling agent, and after mechanical characteristics are compensated, the final paste penetration is obtained to configure the final coupling agent paste, so that the magnetic coupling performance of the induction electricity taking device is optimized, and the induction electricity taking efficiency is improved; the method is an environment characteristic matching effect evaluation method based on a fiber material science characterization means, feedback compensation is carried out on the proportion of the components of the magnetic coupling agent paste, and the induction electricity taking efficiency of a specific application environment is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of inductive power extraction of power transmission lines, and in particular to a method for improving the efficiency of inductive power extraction based on magnetic coupling. Background Art

[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 transmission cables. At present, the commonly used power supply methods of online monitoring equipment are: battery, solar energy, laser, capacitor voltage division online energy acquisition and induction power acquisition. Induction power acquisition adopts non-contact induction power acquisition technology, which has the advantages of high safety, low cost, small size and wide application range compared with other methods, so it is widely used.

[0003] However, the inductive power-taking device has a harsh working environment, is difficult to maintain, and is prone to poor magnetic coupling, increased magnetic resistance, and reduced inductive power-taking efficiency. At the same time, the inductive power-taking device has installation and disassembly requirements, and a fixed magnetic coupling method cannot be used. At present, in order to solve the problem of energy efficiency decline of the magnetic moving contact inductive power-taking device in high-power applications, there are three directions: optimizing materials, optimizing topological structures, and optimizing magnetic circuit coupling methods. The material optimization direction is such as selecting nanocrystalline material cores and using a dual core working in parallel. At low currents, energy is transferred through the gapless core. As the current increases, the gapless core enters saturation and energy is transferred through the gapped core, but the energy transmission is unstable. The topological structure optimization direction is such as improving the magnetic circuit topological structure method, which reduces the starting current, but increases the line burden and is prone to switching failures, or adding a set of differential coils to the magnetic core to adapt to different current sizes by controlling the access and cut-out, but the control is complex and unstable. Magnetic circuit coupling method optimization, such as the use of magnetic conductive glue, can improve magnetic circuit coupling performance and increase chemical stability, but its disassembly convenience is reduced after curing, which is not conducive to inductive power application. The paste-based coupling agent cannot adapt to 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 degradation of power extraction efficiency of high-power induction power extraction devices caused by different environments. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings and deficiencies of the above-mentioned prior art and to provide a method for improving the efficiency of inductive power extraction based on magnetic coupling. The method for improving the efficiency of inductive power extraction described in the present invention is divided into four steps: determining the environment and magnetic circuit characteristics and setting empirical parameters, preparing a magnetic coupling agent and adjusting the mechanical characteristics, trial use of a magnetic coupling agent and effect evaluation, and compensating for the mechanical characteristics of the coupling agent. The specific contents are as follows: Step 1. Determine the environment and magnetic circuit characteristics and set empirical parameters Different installation environment characteristics will have different impacts on magnetic circuit coupling and put forward different requirements for magnetic coupling agents. Harsh external environments require magnetic coupling agent pastes to have higher mechanical stability and temperature stability, but this may reduce the contact efficiency of the coupling agent and cause the magnetic resistance to increase. Therefore, it is necessary to find a suitable performance value range to obtain the optimal coordination ratio.

[0006] First, the cone penetration is used to characterize the mechanical strength of the paste, and the cone penetration initial value estimation formula including the magnetic core permeability, saturation magnetic flux density, core cross-sectional area, ambient temperature, ambient humidity, and vibration intensity is established: Where Z is the cone penetration, The cone penetration empirical parameter is usually 70-90 (according to the industry standard of 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 just a reference range.) 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, and T is the saturation flux density. The core permeability and saturation flux density of commonly used materials are as follows: Figure 1 shown.

[0007] Step 2. Preparation of magnetic coupling agent and adjustment of mechanical properties The coupling agent can use silicone-based grease as the base oil, and the magnetic conductive material is ceramic ferrite (mainly composed of iron oxide, nickel oxide, zinc oxide, and prepared by ceramic technology), ultra-short fiber mechanical property adjustment filler (such as glass fiber, carbon nanotube, etc.), 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, and finally a preliminary magnetic coupling agent is prepared through vacuum planetary dispersion.

[0008] Step 3. Trial use of magnetic coupling agent and effect evaluation 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.

[0009] The efficiency of inductive power extraction is detected 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.

[0010] 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.

[0011] After all tests, the effects are comprehensively evaluated to obtain the performance error , ranging from 0 to 1.

[0012] Step 4. Compensation of the mechanical properties of the coupling agent Based on the measured performance error, the mechanical properties are compensated and the final paste penetration calculation formula is obtained: 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 accuracy limitations of measurement equipment, changes in environmental conditions, fluctuations in material properties, etc.; set The maximum adjustment value, minimum adjustment value and adjustment step length 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, it means that the adjustment direction is correct; if the performance improvement is not obvious or even decreases, it means that there may be problems with the adjustment strategy and the direction or method needs to be adjusted). To compensate for the posterior cone penetration.

[0013] Then, the binary method is used to experimentally configure the 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.

[0014] The beneficial effects of the present invention are as follows: According to the characteristics of the environment (such as temperature, humidity, vibration, etc.), combined with the magnetic circuit characteristics (such as core magnetic permeability and saturation magnetic flux density), the present invention proposes an initial cone penetration estimation formula to accurately coordinate the mechanical performance indicators of the magnetic coupling agent, and by adjusting the proportion of a single component, the coupling agent paste hardness, temperature stability and other properties are adjusted without affecting other properties to configure a preliminary magnetic coupling agent, and then the effect of the magnetic coupling agent is tested for error correction, and 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

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0016] Figure 1 This is a characteristic diagram of commonly used magnetic core materials; Figure 2 A schematic diagram of the position of the contact surface of the magnetic circuit of the induction power supply device (with an air gap in the magnetic core); Figure 3 This is the schematic diagram of induction power supply; Figure 4 is a schematic diagram of the cross section of the magnetic core; Figure 5 is a flow chart of the present invention; Figure 6 is the relationship between cone penetration and graphene content; Figure 7 It is the relationship between cone penetration and compound graphite powder content. DETAILED DESCRIPTION

[0017] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with embodiments and drawings.

[0018] The method for improving the efficiency of inductive power extraction described in the present invention is divided into four steps: determining the environment and magnetic circuit characteristics and setting empirical parameters, preparing the magnetic coupling agent and adjusting the mechanical characteristics, testing the magnetic coupling agent and evaluating the effect, and compensating the mechanical characteristics of the coupling agent; the specific contents are as follows: Step 1. Determine the environment and magnetic circuit characteristics and set empirical parameters Different installation environment characteristics will have different impacts on magnetic circuit coupling and put forward different requirements for magnetic coupling agents. Harsh external environments require magnetic coupling agent pastes to have higher mechanical stability and temperature stability, but this may reduce the contact efficiency of the coupling agent and cause the magnetic resistance to increase. Therefore, it is necessary to find a suitable performance value range to obtain the optimal coordination ratio.

[0019] First, the cone penetration is used to characterize the mechanical strength of the paste, and the cone penetration initial value estimation formula including the magnetic core permeability, saturation magnetic flux density, core cross-sectional area, ambient temperature, ambient humidity, and vibration intensity is established: Where Z is the cone penetration, The empirical parameter for cone penetration is usually 70-90. 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, and T is the saturation flux density. The core permeability and saturation flux density of commonly used materials are as follows: Figure 1 shown.

[0020] Step 2. Preparation of magnetic coupling agent and adjustment of mechanical properties The coupling agent can use silicone-based grease as the base oil, and the magnetic conductive material is ceramic ferrite (mainly composed of iron oxide, nickel oxide, zinc oxide, and prepared by ceramic technology), ultra-short fiber mechanical property adjustment filler (such as glass fiber, carbon nanotube, etc.), 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, and finally a preliminary magnetic coupling agent is prepared through vacuum planetary dispersion.

[0021] Step 3. Trial use of magnetic coupling agent and effect evaluation 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.

[0022] The efficiency of inductive power extraction is detected 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.

[0023] 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.

[0024] After all tests, the effects are comprehensively evaluated to obtain the performance error , ranging from 0 to 1.

[0025] Step 4. Compensation of the mechanical properties of the coupling agent Based on the measured performance error, the mechanical properties are compensated and the final paste penetration calculation formula is obtained: in For the adjustment range (through accurate identification of the error source, the α parameter can be adjusted more specifically, thereby compensating for the performance error more effectively. Error sources include the accuracy limitations of the measuring equipment, changes in environmental conditions, fluctuations in material properties, etc.; set the maximum adjustment value, minimum adjustment value and adjustment step of α, and judge 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, it means that the adjustment direction is correct; if the performance improvement is not obvious or even decreases, it means that there may be problems with the adjustment strategy and the direction or method needs to be adjusted), To compensate for the posterior cone penetration.

[0026] Then, the binary method is used to experimentally configure the 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.

[0027] Example 1. Cone penetration test The cone penetration of magnetic coupling agent mainly reflects the degree of hardness. The cone penetration is measured at 25°C when the cone assembly is released from the cone penetration meter, the cone is allowed to fall for 5 seconds, and the depth of its penetration into the sample is measured. Usually, the cone penetration in the non-working state (25°C, 1 / 4 cone and cone rod assembly, 5S drop, record the depth of the cone drop) is between 70 and 90. Referring to the data in Table 1, 5 magnetic coupling agents with different concentrations of ceramic ferrite were prepared. The other components were silicone-based grease and ultra-short fiber mechanical property adjustment fillers. The proportion was determined by dichotomy. The specific mechanical property adjustment filler ratio was determined by experiment, and the cone penetration performance of these 5 magnetic coupling agents was tested.

[0028] Table 1 Relationship between cone penetration and ceramic ferrite content After testing, the cone penetration of the magnetic coupling agent shows a linear decreasing trend with the increase of the ceramic ferrite content. The cone penetration of the magnetic coupling agent with 77% and 78% ceramic ferrite content reaches 95.4 and 91.5 respectively, which exceeds the use requirements of actual working conditions and cannot meet the use requirements. Because the cone penetration of the magnetic coupling agent is too large, the overall viscosity of the grease is low, and it is easy to flow when applied to the electrical contact area in the actual use environment, thereby destroying the quality of the electrical connection.

[0029] Referring to the data in Table 2, 5 magnetic coupling agents with different concentrations of graphene added were prepared, and the cone penetration performance of these 5 magnetic coupling agents was tested.

[0030] Table 2 Relationship between cone penetration and graphene content Figure 6 The graph shows the relationship between cone penetration (0.1mm) and graphene content (wt%). As the graphene content increases, the cone penetration of the magnetic coupling agent gradually decreases. When 3% graphene is added, the cone penetration of the magnetic coupling agent reaches 97.8, which is obviously too large and cannot meet the engineering requirements. When the graphene content reaches 5%, the reduction effect begins to slow down and eventually stabilizes. As the graphene content continues to decrease, the cone penetration of the magnetic coupling agent with a 3% graphene content decreases from 97.8 to 71.4, with a decrease of 26.4 cone penetrations. This has a lot to do with the structure of graphene itself. Graphene has a large specific surface area and a thickness of only 1.5nm. This nano-level structural feature makes it possible for a slight increase in the content of graphene to cause changes in the colloidal stability of the magnetic coupling agent.

[0031] The above test examined the changes in the cone penetration of the magnetic coupling agent by adding a single ceramic ferrite and graphene content. It can be found that with the increase of the conductive filler content, the cone penetration gradually decreases. In order to verify the effect of graphene on the cone penetration, the formula was compounded, 1% graphene was compounded and mixed with ceramic ferrite to prepare the conductive filler of the magnetic coupling agent. With the continuous change of the overall filler, the cone penetration of the magnetic coupling agent was observed, as shown in Table 3.

[0032] Table 3 Relationship between cone penetration and compound graphene powder content Figure 7 The relationship curve of cone penetration (0.1mm) and compound graphene powder content (wt%) shows that with the increase of compound graphene powder content, the cone penetration of magnetic coupling agent shows a trend of gradual decrease. When the concentration of conductive filler is 69% and 70%, the cone penetration of magnetic coupling agent is 95.7 and 91.6, which causes the viscosity of magnetic coupling agent to decrease and cannot meet the actual engineering needs. Continuing to increase the content of conductive filler, the magnetic coupling agent decreases slowly. When the filler content is 73%, the cone penetration is 82.7, with a decrease of 13 cone penetrations, and finally tends to be flat.

[0033] The above article conducts a horizontal data analysis on the cone penetration of the magnetic coupling agent with different contents of the same filler. In order to further analyze the changes in the cone penetration of the three types of magnetic coupling agents with different fillers and different contents, and explore the reasons for the differences, a longitudinal comparative analysis of the cone penetration of these three magnetic coupling agents is conducted based on the data in Table 4. Among them, Ⅰ, Ⅱ, Ⅲ, Ⅳ and Ⅴ are five groups of data, corresponding to the filler concentration (wt%) of all fillers from one to five groups.

[0034] Table 4 Cone penetration data comparison of five different filler contents (0.1mm) The study found that with the increase of filler content, the cone penetration of the three types of magnetic coupling agents showed a decreasing trend. Among them, the cone penetration of graphene magnetic coupling agent decreased most significantly, from 97.8 to 71.4, a decrease of 26.4. The decrease in cone penetration of ceramic ferrite and compound graphene magnetic coupling agents was not much different, 14.9 and 13 respectively, which was relatively gentle. The overall decrease in cone penetration was: graphene magnetic coupling agent > ceramic ferrite magnetic coupling agent > compound graphene magnetic coupling agent.

[0035] Under the same conditions of thickener and silicone oil matrix, the main factor affecting the cone penetration is the filler particle size. Combined with the data in Table 4, it can be concluded that the magnetic coupling agent prepared with 2μm ceramic ferrite, nano-graphene and compound graphene as fillers, the smaller the filler particle size and the larger the specific surface area, the greater the decrease in cone penetration. It can be seen that the particle size and specific surface area of ​​the filler material have a great influence on the variation trend of cone penetration. If the cone penetration is too large (greater than 90), the viscosity of the grease is low, and it is easy to lose when applied to the electrical contact area in the actual use environment, and the high temperature resistance will be greatly reduced, making the magnetic coupling agent ineffective. The magnetic coupling agent is too hard (less than 70), and it is easy to bubble and dry up during the actual application process, resulting in the electrical contact area not being fully contacted, which will increase the contact resistance and damage the quality of the electrical connection.

[0036] 2. Power test The power test is performed using a current sensor device based on inductive power extraction. Given the core material, core size, core parameters, etc. of the current sensor, this method is used to optimize the inductive power extraction efficiency of the current sensor. The power test is performed by changing the output voltage. When the output voltage reaches 1000V, the maximum power at the load end is 138.74 W. This proves that this method can improve the stability and efficiency of various inductive power extraction devices on the transmission line.

[0037] In summary, the beneficial effects of the present invention are significant and multi-dimensional, mainly reflected in the following aspects: By analyzing the characteristics of different installation environments in detail, such as temperature, humidity, vibration, etc., combined with magnetic circuit characteristics such as core permeability and saturation magnetic flux density, the present invention proposes a cone penetration initial value estimation method that 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, effectively avoids performance degradation caused by mismatching of the environment or magnetic circuit characteristics, and lays a solid foundation for improving the efficiency of inductive power extraction.

[0038] In the preparation process of magnetic coupling agent, by adjusting the proportion of a single component, the mechanical properties such as hardness and temperature stability of the paste can be adjusted over a wide range without compromising other key properties. This flexibility not only meets the special needs of different application environments, but also optimizes the overall performance of the coupling agent, reduces magnetic circuit loss, and improves energy transmission efficiency.

[0039] The present invention introduces an effect evaluation method based on the combination of fiber material characterization and power detection. Through accelerated aging operation in actual environment and relatively intuitive power detection, the performance of magnetic coupling agent and its influence on induction power efficiency are comprehensively evaluated. This scientific evaluation not only ensures the accuracy and reliability of the evaluation results, but also provides strong support for subsequent performance optimization.

[0040] In response to the performance errors in the evaluation results, the present invention proposes a mechanical property compensation mechanism, which achieves accurate compensation for the coupling agent performance by adjusting the parameters in the cone penetration formula. Combined with the dichotomy experimental configuration, the optimal coupling agent formula was finally determined. This process not only improves the efficiency of inductive power extraction, but also ensures the stability and reliability of the coupling agent during long-term use, providing a strong guarantee for the application of inductive power extraction technology.

[0041] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

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 setting of empirical parameters: Use cone penetration to characterize the mechanical strength of magnetic coupling agent paste, and establish an initial cone penetration estimation formula including core magnetic permeability, saturation magnetic flux density, core cross-sectional area, ambient temperature, ambient humidity, and vibration intensity: Where Z is the cone penetration; It is the empirical parameter of cone penetration, and its value range is 60~80; is the adjustment factor; is the magnetic permeability of the core; S is the cross-sectional area of ​​the core; 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 cone penetration initial value 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 effect evaluation of magnetic coupling agent: Apply the preliminary magnetic coupling agent prepared in S2 to the magnetic circuit contact surface of the induction power supply device, install the equipment, perform accelerated aging operation with reference to the actual environment, test the induction power supply efficiency and the degradation rate of the magnetic circuit contact surface, and after the test, conduct a comprehensive evaluation of the effect to obtain the 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 experimentally determined using the 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 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 spectrum, and Raman spectrum 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 cone penetration Z2, the coupling agent paste is configured through experiments using the dichotomy method to determine the corresponding mechanical filler ratio, and the final coupling agent formula is obtained to achieve an improvement in the induction power extraction efficiency based on a specific environment.

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