Magnetic field electricity taking device and electricity taking performance improving method

Abstract

The invention discloses a magnetic field electricity taking device and an electricity taking performance improving method, the device comprises an energy taking winding and an auxiliary winding which share one magnetic core, the energy taking winding is connected to a resistive load, the auxiliary winding is connected to an energy adjusting capacitor, and under the condition that the magnetic core material, the magnetic core size, the number of turns of double windings and the load change interval are fixed, the energy adjusting capacitor is connected to the energy taking winding. By adjusting the capacitance value of the energy adjusting capacitor, the optimal energy adjusting capacitance value is selected to obtain the maximum output power of the load, and it is ensured that the magnetic core works in a linear working interval. According to the method, the output power is improved and the magnetic flux saturation influence is reduced through the coupling effect of the double windings and the adjustment of the energy adjustment capacitance value, a high-cost-performance magnetic core material is used, parameters such as the magnetic core size, the number of turns of the double windings and the load change interval are fixed, and the optimal energy adjustment capacitance value selection method is provided; and a method for promoting desaturation of the magnetic core by the energy adjusting capacitor is researched.

Description

Technical Field

[0001] This invention relates to technologies for improving the power extraction performance of magnetic fields, and in particular to a magnetic field power extraction device and a method for improving power extraction performance. Background Technology

[0002] With the ongoing development of smart grids, the large-scale deployment of power equipment condition sensing devices in core equipment such as transmission and transformation lines and transformers has formed a multi-dimensional monitoring network. However, due to the complexity of the electromagnetic environment in medium- and high-voltage fields and the insulation limitations of the equipment itself, traditional chemical battery power supply modes pose risks of periodic interruptions and ecological pollution. Especially for critical nodes requiring long-term online monitoring, reliable power supply for power equipment condition sensing devices has become a key bottleneck restricting their large-scale deployment. Against this backdrop, self-powered solutions based on environmental energy harvesting technology have emerged, providing a maintenance-free and sustainable power supply path for power equipment condition monitoring systems through spatial energy capture and conversion mechanisms. Currently, the power supply systems for power equipment condition sensing devices mainly rely on intermittent environmental energy harvesting technologies, such as photovoltaic power generation, wind power, thermal gradation utilization, mechanical vibration capture, and radio frequency energy harvesting. These environmental energy harvesting methods are typically used in combination with energy storage battery packs. However, these intermittent power supply schemes generally suffer from inherent defects such as insufficient energy acquisition stability. In contrast, the power frequency electromagnetic field formed around the perimeter of power transmission trunk lines and rail transit conductors has become the core focus of research on self-powering technology for new energy power systems due to its significant advantages such as wide spatial distribution, stable power density, and continuous energy. Magnetic field power harvesting technology uses a combination of magnetic cores and power harvesting windings to pick up spatial magnetic field energy to power the status sensing devices of power equipment. Its power harvesting density is far superior to that of electric field power harvesting technology, making it suitable for powering status sensing devices of power equipment with multiple power levels and diverse operating modes. However, because the current in current-carrying conductors such as transmission lines fluctuates from several amperes to thousands of amperes with changes in the connected load, magnetic field power harvesting devices will experience unstable operating status and power harvesting. That is, there is a power supply dead zone when the line current is small, and the magnetic core is prone to saturation and even burnout when the line current is large. The nonlinear saturation effect of the magnetic core can cause secondary problems such as output voltage distortion and increased equipment vibration, which pose a serious challenge to the safe and stable operation of the power harvesting device. To address the issues of low start-up threshold for low-current circuits and core saturation suppression for high-current circuits in magnetic field power harvesting devices, researchers have made a series of significant achievements in the optimization design of energy harvesting windings and cores, as well as the design of magnetic field power harvesting circuits. Existing magnetic field power harvesting technologies all introduce additional power conversion circuits to improve power output and control core saturation. These power conversion circuits still require an additional auxiliary power supply. Furthermore, existing magnetic field power harvesting technologies are caught in a "performance improvement paradox": while using high-performance cores such as permalloy and nanocrystalline alloys can increase power output, it leads to a surge in material costs and increased process complexity; and while traditional weakly permeable cores have a cost advantage, their non-closed magnetic circuit structure causes magnetic leakage losses, and their inherent low permeability severely restricts energy conversion efficiency. Summary of the Invention

[0003] Purpose of the invention: The purpose of this invention is to provide a method for improving the magnetic field power extraction performance of a weakly conductive magnetic core based on the coupling characteristics of dual windings. This method improves output power and reduces the impact of magnetic flux saturation by utilizing the coupling effect of dual windings and adjusting the value of the energy regulation capacitor.

[0004] Technical solution: The magnetic field power extraction device of the present invention includes an energy extraction winding and an auxiliary winding sharing a common magnetic core. The energy extraction winding is connected to a resistive load, and the auxiliary winding is connected to an energy adjustment capacitor. Under the condition that the magnetic core material, magnetic core size, number of turns of the dual windings and load variation range are fixed, the maximum output power of the load can be obtained by adjusting the capacitance value of the energy adjustment capacitor and selecting the optimal energy adjustment capacitor value while ensuring that the magnetic core works in the linear operating range.

[0005] Optionally, the magnetic core is mounted on the power line and extracts electrical energy from the power line through the energy harvesting winding.

[0006] Optionally, when the magnetic core is a weakly permeable magnetic core, the output power can be increased and the effect of magnetic flux saturation can be reduced by the coupling effect of the dual windings and the addition of an optimal energy regulation capacitor.

[0007] Optional, optimal energy regulation capacitor The calculation formula is: Among them, I2 # It is the current flowing through the auxiliary winding, ω is the angular frequency, and N C The number of turns of the auxiliary winding, μ is the permeability, f is the line current frequency, r1, r2 and h are the inner radius, outer radius and height of the magnetic core, respectively, and I e R1 is the excitation current, and R2 is the internal resistance of the auxiliary winding.

[0008] Optionally, when the air gap of the magnetic core exists, for different magnetic core materials and under different loads, there is an optimal electric field power extraction capacitor that enables the load output power to reach the optimal value. Furthermore, when the magnetic core is saturated, the energy regulation capacitor value can be increased through the coupling effect of the dual windings to improve the output power and reduce the impact of magnetic flux saturation.

[0009] Optionally, if an air gap exists in the magnetic core, the magnetic core can be kept away from saturation by selecting an energy adjustment capacitor value.

[0010] The method for improving the magnetic field power extraction performance based on the device described in this invention includes the following steps:

[0011] Select the core material, core size, number of turns in the dual windings, and load variation range;

[0012] Calculate the optimal energy regulation capacitor value Among them, I2 # It is the current flowing through the auxiliary winding, ω is the angular frequency, and N CThe number of turns of the auxiliary winding, μ is the permeability, f is the line current frequency, r1, r2 and h are the inner radius, outer radius and height of the magnetic core, respectively, and I e R1 is the excitation current, and R2 is the internal resistance of the auxiliary winding;

[0013] The calculated optimal energy regulation capacitor value is applied to the auxiliary winding, and the line current change is monitored. If the line current continues to increase and a distorted spike wave appears at the load end, the magnetic core enters the saturation state. Then, the optimal energy regulation capacitor value is adjusted to make the magnetic core enter the linear operating range.

[0014] Furthermore, before applying the calculated optimal energy regulation capacitor value to the auxiliary winding, the process also includes: verifying and fine-tuning the calculated optimal energy regulation capacitor value based on simulation and experiments to obtain the optimal energy regulation capacitor value applicable to the actual circuit.

[0015] Furthermore, the optimal energy regulation capacitor value The calculation method is as follows:

[0016] The current I2 flowing through the auxiliary winding was calculated. # The energy regulation capacitor C obtained by reverse calculation r This is the optimal energy regulation capacitor value. The current I2 flowing through the auxiliary winding # The calculation formula is:

[0017]

[0018] Where E2 is the auxiliary winding voltage, C r It is an energy regulation capacitor.

[0019] Furthermore, the method for adjusting the optimal energy regulation capacitor value to bring the magnetic core into the linear operating range is as follows: by gradually increasing the optimal energy regulation capacitor value, the magnetic core enters the linear operating range.

[0020] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are as follows: By using an energy regulating capacitor, when selecting a low-cost but relatively low-permeability magnetic core material, the difference between the load output power and the load output power when using a magnetic core material with higher permeability can be significantly reduced, which can reduce the manufacturing cost of the magnetic field power extraction device. At the same time, due to the coupling effect of the dual windings, the magnetic core can be taken out of saturation by increasing the energy regulating capacitor, thereby expanding the linear operating range of the magnetic core. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a magnetic field power extraction device based on the coupling characteristics of two windings.

[0022] Figure 2The equivalent circuit diagram and vector diagram of the magnetic field power extraction device based on the dual-winding coupling characteristics are shown in (a) and (b).

[0023] Figure 3 Magnetization curves of the magnetic core under different air gaps;

[0024] Figure 4 The load output power varies with the ERC capacitor when there is no air gap in the magnetic core in the method of the present invention. (a) is the load output power varying with the ERC capacitor when the relative permeability is 100000, and (b) is the load output power varying with the ERC capacitor when the relative permeability is 2300.

[0025] Figure 5 The magnetic flux density of the magnetic core varies with the ERC capacitance when there is no air gap in the magnetic core in the method of the present invention. (a) shows the magnetic flux density of the magnetic core varies with the ERC capacitance when the relative permeability is 100000, and (b) shows the magnetic flux density of the magnetic core varies with the ERC capacitance when the relative permeability is 2300.

[0026] Figure 6 The load output power varies with the ERC capacitor when the magnetic core air gap exists in the method of the present invention. (a) is the load output power varying with the ERC capacitor when the relative permeability is 100000, and (b) is the load output power varying with the ERC capacitor when the relative permeability is 2300.

[0027] Figure 7 The magnetic flux density of the magnetic core varies with the ERC capacitance when the air gap of the magnetic core exists in the method of the present invention. (a) shows the magnetic flux density of the magnetic core varies with the ERC capacitance when the relative permeability is 100000, and (b) shows the magnetic flux density of the magnetic core varies with the ERC capacitance when the relative permeability is 2300.

[0028] Figure 8 This is a schematic diagram of the experimental prototype of the dual-winding magnetic field power extraction device in an embodiment of the present invention;

[0029] Figure 9 The experimental results of the load output power and the output power ratio as a function of the ERC capacitor value in the method of the present invention are shown in (a) when the air gap is absent and (b) when the air gap is present.

[0030] Figure 10 The experimental results of the output power changing with load value in the method of the present invention are shown in (a) when the air gap is not present and (b) when the air gap is present.

[0031] Figure 11 The output voltage waveforms in the method of this invention are shown in (a) and (b). (a) is the core saturation waveform, and (b) is the core desaturation waveform. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] like Figure 1 As shown in the figure, R L C is the load actually connected to one side of the winding of the magnetic field power extraction device. r The capacitor connected to the other winding is called the energy regulating capacitor (ERC), N L and N C These are the loads R L and the connected capacitor C r The corresponding number of winding turns, where N L and N C The corresponding windings are called the energy extraction winding and the auxiliary winding, respectively. The auxiliary winding is connected to a capacitive variable, and the energy extraction winding is connected to a resistive load. Due to the addition of the auxiliary winding and the energy management capacitor, the excitation current I... e The increase in magnetic flux density B in the magnetic core leads to an increase in the induced current on the load side, thereby increasing the maximum output power of the load.

[0034] The performance improvement of the magnetic field power extraction device is mainly due to the increase in energy extraction power or the suppression of magnetic core saturation. The two windings are the energy extraction winding and the auxiliary winding, respectively. With the parameters such as magnetic core material, magnetic core size, number of turns of the two windings and load variation range fixed, the optimal energy adjustment capacitor value can be selected through calculation and simulation to obtain the maximum power and ensure that the magnetic core works in the linear operating range.

[0035] The effect of the energy regulation capacitor on the maximum output power and magnetic flux density of the load is affected by the magnetic permeability of the magnetic core. In the absence of a magnetic core air gap, when the magnetic field power extraction device uses a magnetic core material with high magnetic permeability, after the energy regulation capacitor value reaches a certain value, the output power and magnetic flux density corresponding to each load value decay at a relatively fast rate. When the initial relative magnetic permeability of the magnetic core is low, there is an optimal electric field power extraction capacitor under different loads that makes the load output power reach the optimal value. When the magnetic field power extraction device uses a low-cost magnetic core material, the output power can be increased and the magnetic flux saturation effect can be reduced by adjusting the energy regulation capacitor value through the coupling effect of the dual windings.

[0036] In the absence of a magnetic core air gap, the energy regulating capacitor expands the magnetic core operating range of the magnetic field power extraction device without an air gap by reducing the magnetic core saturation.

[0037] With the presence of an air gap in the magnetic core, regardless of whether high or low permeability materials are used, there exists an optimal electric field tapping capacitor under different loads to ensure that the load output power reaches the optimal value. Furthermore, when the magnetic core is saturated, the output power can be increased and the effect of magnetic flux saturation can be reduced by adjusting the energy regulation capacitor value through the coupling effect of the dual windings.

[0038] This invention also provides a method for improving the magnetic field power extraction performance of a weakly permeable magnetic core based on the coupling characteristics of dual windings. This method increases output power and reduces the impact of magnetic flux saturation by utilizing the coupling effect of the dual windings and adjusting the energy regulation capacitor value. The method includes the following steps:

[0039] (1) Select a high-performance magnetic core material and fix parameters such as core size, number of turns in the dual windings, and load variation range. Based on the law of conservation of magnetomotive force, draw... Figure 1 The equivalent circuit model and vector diagram of the magnetic field power extraction device of the illustrated apparatus are provided, and the relevant parameters are calculated, such as... Figure 2 As shown in (a) and (b). Figure 2 In (a), when the magnetic field power extraction device is in linear operation, the energy conversion efficiency between the power line and the power extraction winding and auxiliary winding is high, the core iron loss is low, and I1, I e These are the line current and the magnetizing current, I1, respectively. # and I2 # R1 and L1 are the currents flowing through the magnetic field energy extraction winding and the auxiliary winding, respectively. R1 and L1 are the internal resistance and leakage inductance of the magnetic field energy extraction winding, respectively. R2 and L2 are the internal resistance and leakage inductance of the auxiliary winding, respectively. U C For capacitor C r voltage, R m and L m These are the excitation resistor and excitation inductor on the power line side, respectively. The energy harvesting core uses a high-permeability material, and the excitation resistor R is negligible. m And the leakage inductance L1 of the energy extraction winding and the leakage inductance L2 of the auxiliary winding, according to the law of electromagnetic induction, the induced voltages e1(t) and e2(t) of the energy extraction winding and the auxiliary winding are respectively expressed as:

[0040]

[0041] Where Φ is the magnetic flux inside the core, ρ is the integral variable of the core radius, r1, r2 and h are the inner radius, outer radius and height of the core, respectively, μ is the permeability, f is the frequency of the line current, ω = 2πf, and ω is the angular frequency.

[0042]

[0043] Where, μ0 and μ r Here, δ represents the vacuum permeability and the relative permeability of the core, respectively, and l represents the average perimeter of the magnetic field lines. From equation (2), it can be seen that as the core air gap increases, the equivalent permeability of the energy-harvesting core decreases linearly. The currents flowing through the auxiliary winding and the magnetic field energy-harvesting winding are respectively expressed as:

[0044]

[0045] Where E1 is the voltage of the energy extraction winding, E2 is the voltage of the auxiliary winding, and Γ1 and Γ2 are intermediate variables.

[0046] (2) The optimal value of the energy regulation capacitor can be obtained through formula (3), and the optimal value is: Calculate the load power output value after adding the optimal energy regulation capacitor. Figure 2 In (b), Φ is the magnetic flux inside the core, where γ is and The included angle can be represented as:

[0047] γ=arctan(ωC r R2) －1 (4)

[0048] By the Pythagorean theorem, we can obtain:

[0049] (I e -N C I2 # sinγ) 2 +(N L I1 # +N C I2 # cosγ) 2 =I1 2 (5)

[0050] Excitation current I e The relationship between the line current I1 and the line current I1 can be expressed as:

[0051]

[0052] Here, Γ3 is an intermediate variable.

[0053] The load output power P can be expressed as:

[0054] P=(I1 # ) 2 R L =(Γ1I e ) 2 R L =Γ1 2 Γ3 2 I1 2 R L (7)

[0055] Furthermore, the calculated optimal value of the energy regulation capacitor can be further verified and fine-tuned through simulation and experiments to obtain the optimal energy regulation capacitor value applicable to actual circuits.

[0056] (3) Apply the optimal energy regulation capacitor value obtained from calculation or simulation to the auxiliary winding and monitor the line current change. If the line current continues to increase, a distorted spike wave will appear at the load end. According to Ampere's circuital law, the following can be seen:

[0057]

[0058] Where H is the magnetic field strength, and the magnetic flux density of the magnetic core can be expressed as:

[0059]

[0060] Where B is the magnetic flux density of the magnetic core.

[0061] Therefore, when the magnetic core enters saturation, the core can be brought into the linear operating range by gradually increasing the energy regulation capacitor value.

[0062] Figure 3 The graph shows the magnetization curves of the magnetic core under different air gaps. In the graph, δ1 and δ2 represent different air gap widths. As can be seen from the graph, the maximum saturation magnetic flux density B sat Dependent on the inherent and unchangeable properties of the magnetic core, the core permeability is the ratio of the magnetic flux density B to the magnetic field strength H before saturation, i.e., μ = B / H. As the air gap in the core increases, the core permeability gradually decreases, and the magnetic field strength corresponding to the critical saturation point of the core also increases. The air gap improves the core's resistance to saturation under high current conditions in power lines, but the weak magnetic permeability of the magnetic field power harvesting device becomes more pronounced, gradually reducing its power harvesting capacity. It is important to note that the magnetic flux density of the magnetic core in the actual operating state of the magnetic field power harvesting device should not exceed the maximum saturation magnetic flux density B. sat If the magnetic core always operates in a deep saturation state, the core loss will increase dramatically, causing the magnetic field power extraction device to remain at a high temperature. The magnetostrictive effect will intensify when the magnetic core is saturated, causing mechanical vibration of the magnetic core. The lifespan of the magnetic field power extraction device (such as winding insulation and heat dissipation structure) will be significantly shortened.

[0063] Figure 4 This paper presents a method to improve the magnetic field power extraction performance of a weakly permeable magnetic core based on the coupling characteristics of dual windings. The load output power varies with the ERC capacitor when the air gap is absent. Taking PC40 and 1K107 cores as examples, the initial relative permeabilities are 2300 and 100000, respectively. The line current is set to 10A, and the core is temporarily without an air gap. The calculated and simulated results are shown below. Figure 4 As shown in (a) and (b). From Figure 4 As shown in (a), when the magnetic field power extraction device uses a high-permeability core material, the load output power remains relatively constant and high in the initial stage as the ERC capacitance value gradually increases. This is because when the ERC capacitance value is small, the winding branch is basically in an open-circuit state. As the ERC capacitance value continues to increase, the output power corresponding to each load value becomes more sensitive to changes in the ERC capacitance value. When the ERC capacitance value reaches a certain value, the output power corresponding to each load value decays at a relatively fast rate. And from... Figure 4From (b), it can be seen that when the initial relative permeability of the magnetic core is low, under different loads, there exists an optimal electric field extraction capacitor that allows the load output power to reach the optimal value. This shows that when the magnetic field power extraction device uses inexpensive magnetic core materials, its output power can approach that of a high-permeability magnetic field power extraction device through the coupling effect of the dual windings and by adjusting the ERC capacitance value. Figure 4 As shown in (a) and (b), under the condition of no air gap in the magnetic core, the theoretical calculation and simulation results are almost in agreement.

[0064] Figure 5 This paper presents a method for improving the magnetic field power extraction performance of a weakly permeable magnetic core based on the coupling characteristics of dual windings. The magnetic flux density of the core varies with the ERC capacitance when the air gap is absent. Figure 5 As shown in (a) and (b), when there is no air gap in the magnetic core, the trend of magnetic core flux density with ERC capacitance value is the same as that of load output power with ERC capacitance value. For the same load, the magnetic core flux density with higher relative permeability is significantly lower than that with lower relative permeability. It is worth noting that as the ERC capacitance value increases, the magnetic core flux density with higher relative permeability continues to decrease after maintaining a high level, and the magnetic core flux density with higher relative permeability effectively decreases after reaching its peak value. This indicates that the ERC capacitance value has a regulating effect on the working range of the magnetic core of the magnetic field power extraction device without an air gap.

[0065] Figure 6 This paper presents a method to improve the magnetic field power extraction performance of a weakly permeable magnetic core based on the coupling characteristics of dual windings. The load output power varies with the ERC capacitor in the presence of an air gap. The air gap size is set to 0.24 mm. The results are compared with... Figure 6 As shown in (a) and (b), under different loads, when the air gap in the magnetic core exists and the ERC capacitance value is low, even if the magnetic field power extraction device uses a high-permeability magnetic core, its output power still decreases sharply. However, there is still an optimal ERC capacitance value that allows the load output power to reach its maximum value. That is, the ERC has a certain compensating effect on the power loss of the weak permeability magnetic field power extraction device with an air gap. Similarly, when the relative permeability decreases to 2300, the ERC capacitance value still has a regulating effect on the load output power, and the optimal ERC capacitance value is close to the optimal ERC capacitance value of the high-permeability magnetic field power extraction device. It is worth noting that... Figure 6 The simulation results in (a) and (b) show a significant discrepancy with the calculated results. This is because the air gap in the magnetic core has an edge effect in the simulation, which leads to a discrepancy between the simulated equivalent magnetic permeability and the calculated equivalent magnetic permeability. As a result, there is a difference between the simulated and calculated load output power results. However, this does not affect the effect of the ERC capacitor value on improving the load output power of the weak magnetic field power extraction device.

[0066] Figure 7This paper presents a method for improving the magnetic field power extraction performance of a weakly permeable magnetic core based on the coupling characteristics of dual windings. The load output power varies with the ERC capacitance when an air gap exists. Figure 7 As shown in (a) and (b), when there is an air gap in the magnetic core, the trend of the magnetic flux density of the magnetic core with the ERC capacitance value is still the same as that of the load output power with the ERC capacitance value. Different magnetic field power-taking devices with different relative permeability all have a maximum magnetic flux density under the change of ERC capacitance value. However, as the ERC capacitance value increases, the magnetic flux density of the magnetic field power-taking device continues to decrease after reaching the peak value. This also proves that when there is an air gap in the magnetic core, the magnetic core can still be kept away from the saturation state by selecting an appropriate ERC capacitance value.

[0067] Figure 8 This is an experimental prototype platform for a dual-winding energy harvesting device. The experimental parameters are shown in Table 1.

[0068] Table 1 Experimental parameters

[0069]

[0070] During the experiment, the high-current generator was adjusted to simulate the current fluctuation of the power transmission and transformation line. The output current was monitored in real time by a clamp-type ammeter. A high-power non-inductive resistor was used as the load to analyze and verify the output power enhancement and saturation characteristic control of the dual-winding magnetic field power extraction device.

[0071] Figure 9 This paper presents experimental results on the load output power and output power ratio as a function of ERC capacitance, based on a method to improve the magnetic field power extraction performance of a weakly permeable magnetic core with dual-winding coupling characteristics. During the experiment, the load was fixed at 50Ω and the line current at 10A. The load output power was recorded by slowly increasing the ERC capacitance value for different magnetic cores and with and without an air gap (0.24mm). The variation characteristics are shown below. Figure 9 As shown in (a) and (b). Figure 9 In (a) and (b), the power ratio refers to the ratio of the output power of the magnetic field power extraction device with and without ERC. Figure 9 As shown in (a), when the air gap is absent, due to the difference in relative permeability, the output power of the weakly permeable PC40 core is lower than that of the highly permeable 1K107 core. However, with the increase of the ERC capacitance value, both cores have an optimal ERC capacitance value that maximizes the output power of the magnetic field power harvesting device. Compared with the magnetic field power harvesting device without an ERC capacitor, the maximum output power of the magnetic field power harvesting devices using PC40 and 1K107 is increased by 1.37 and 1.18 times, respectively. This indicates that ERC has a positive effect on improving the output power of the magnetic field power harvesting device under different core materials. Figure 9As shown in (b), the output power of the magnetic field power harvesting device is significantly reduced when an air gap is present, and the output power of the high-permeability 1K107 and the weak-permeability PC40 is almost the same when an air gap is present. This is because the air gap significantly reduces the equivalent permeability of the magnetic field power harvesting device. Furthermore, with the intervention of ERC, the maximum output power of the magnetic field power harvesting device using PC40 and 1K107 is further increased by a factor of 2.09 and 2.62, respectively, proving the feasibility of ERC in improving the output power of the magnetic field power harvesting device.

[0072] Figure 10 This presents experimental results on the output power variation with load value for a method to improve the magnetic field power extraction performance of a weakly permeable magnetic core based on the coupling characteristics of dual windings. Figure 9 The optimal ERC capacitance values ​​for (a) and (b) are fixed (525 μF for the air gap and 205 μF for the air gap-free). The output power fluctuation characteristics under load changes are analyzed, and the experimental results are as follows: Figure 10 As shown in (a) and (b). From Figure 10 As shown in (a) and (b), when the load range is 10Ω to 100Ω, ERC can improve the output power of the magnetic field power extraction device under various loads, regardless of whether the air gap exists. The maximum output power improvement factors when the magnetic core air gap does not exist and when it exists are about 1.41 and 2.19, respectively. It can be seen that it is feasible to improve the output power under load changes by utilizing the dual winding coupling characteristics of the magnetic field power extraction device.

[0073] Figure 11 The output voltage waveform is presented as an improvement method for the magnetic field power extraction performance of a weakly permeable magnetic core based on the coupling characteristics of a dual-winding system. With fixed load resistance and a core air gap of 50Ω and 0.24mm, the effect of the ERC capacitance value on suppressing the core's operation in saturation mode is analyzed, where the line current increases to 230A. Figure 11 Figures (a) and (b) show the conditions when the magnetic core is operating in saturation (C). r =525μF) and ECR capacitance value (C r The load waveform after increasing (=10525μF). Figure 11 In (a), due to the increase in line current, even though an air gap was installed in the magnetic core to reduce the sensitivity of the magnetic field power extraction device to the impact of large line current, the magnetic field power extraction device still entered a deep saturation state, and a spike-shaped distorted wave appeared at the load end. Figure 11 In (b), when the ECR capacitance increases to 10525μF, the magnetic core exits the deep saturation state, and the output waveform of the magnetic field power extraction device returns to the sinusoidal state. This also proves that the ECR can suppress the saturation state of the magnetic field power extraction device.

[0074] Compared to the complexity and additional energy consumption of traditional power conversion circuits, the energy regulation capacitor based on the coupling characteristics of dual windings used in this invention can significantly reduce circuit complexity. This facilitates the diversified development of weak permeability magnetic cores in the field of magnetic field power extraction, reduces the cost of magnetic field power extraction devices, and promotes the widespread application of magnetic field power extraction technology. It can be extended to scenarios such as smart grid monitoring and rail transit power supply, providing a new approach for the development of low-cost, high-reliability self-powered technology. This invention improves output power and reduces the impact of magnetic flux saturation by utilizing the coupling effect of dual windings and adjusting the energy regulation capacitor value. Using cost-effective magnetic core materials and fixing parameters such as core size, number of turns in dual windings, and load variation range, it proposes an optimal method for calculating the energy regulation capacitor value. Furthermore, by gradually increasing the energy regulation capacitor, the magnetic core operates within a linear operating range.

Claims

1. A magnetic field power extraction device, characterized in that, It includes a power extraction winding and an auxiliary winding that share a single magnetic core. The power extraction winding is connected to a resistive load, and the auxiliary winding is connected to an energy regulation capacitor. With the magnetic core material, magnetic core size, number of turns of the dual windings, and load variation range fixed, the maximum output power of the load can be obtained by adjusting the capacitance value of the energy regulation capacitor and selecting the optimal energy regulation capacitor value while ensuring that the magnetic core operates in the linear operating range.

2. The magnetic field power extraction device according to claim 1, characterized in that, The magnetic core is mounted on the power line and extracts electrical energy from the power line through the energy harvesting winding.

3. The magnetic field power extraction device according to claim 1, characterized in that, In the case of no magnetic core air gap, when the magnetic core is a weakly permeable magnetic core, the output power is improved and the effect of magnetic flux saturation is reduced by the coupling effect of the dual windings and the addition of the optimal energy regulation capacitor.

4. The magnetic field power extraction device according to claim 3, characterized in that, Optimal energy regulation capacitor C r The formula for calculating * is: Among them, I2 # It is the current flowing through the auxiliary winding, ω is the angular frequency, and N C The number of turns of the auxiliary winding, μ is the permeability, f is the line current frequency, r1, r2 and h are the inner radius, outer radius and height of the magnetic core, respectively, and I e R1 is the excitation current, and R2 is the internal resistance of the auxiliary winding.

5. The magnetic field power extraction device according to claim 1, characterized in that, With the presence of an air gap in the magnetic core, for different magnetic core materials and under different loads, there exists an optimal electric field extraction capacitor that enables the load output power to reach the optimal value. Furthermore, when the magnetic core is saturated, the energy regulation capacitor value can be increased through the coupling effect of the dual windings to improve the output power and reduce the impact of magnetic flux saturation.

6. The magnetic field power extraction device according to claim 1, characterized in that, When the air gap in the magnetic core exists, the magnetic core can be kept away from saturation by selecting the value of the energy adjustment capacitor.

7. A method for improving the magnetic field power extraction performance of the device according to any one of claims 1 to 6, characterized in that, Includes the following steps: Select the core material, core size, number of turns in the dual windings, and load variation range; Calculate the optimal energy regulation capacitor value Among them, I2 # It is the current flowing through the auxiliary winding, ω is the angular frequency, and N C The number of turns of the auxiliary winding, μ is the permeability, f is the line current frequency, r1, r2 and h are the inner radius, outer radius and height of the magnetic core, respectively, and I e R1 is the excitation current, and R2 is the internal resistance of the auxiliary winding; The calculated optimal energy regulation capacitor value is applied to the auxiliary winding, and the line current change is monitored. If the line current continues to increase and a distorted spike wave appears at the load end, the magnetic core enters the saturation state. Then, the optimal energy regulation capacitor value is adjusted to make the magnetic core enter the linear operating range.

8. The method for improving the magnetic field power extraction performance according to claim 7, characterized in that, The process of applying the calculated optimal energy regulation capacitor value to the auxiliary winding also includes: verifying and fine-tuning the calculated optimal energy regulation capacitor value based on simulation and experiments to obtain the optimal energy regulation capacitor value applicable to the actual circuit.

9. The method for improving the magnetic field power extraction performance according to claim 7, characterized in that, Optimal energy regulation capacitor value The calculation method is as follows: The current I2 flowing through the auxiliary winding was calculated. # The energy regulation capacitor C obtained by reverse calculation r This is the optimal energy regulation capacitor value. The current I2 flowing through the auxiliary winding # The calculation formula is: Where E2 is the auxiliary winding voltage, C r It is an energy regulation capacitor.

10. The method for improving the magnetic field power extraction performance according to claim 7, characterized in that, The method to adjust the optimal energy regulation capacitor value to bring the magnetic core into the linear operating range is as follows: gradually increase the optimal energy regulation capacitor value to bring the magnetic core into the linear operating range.

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