Air gap mutual inductor equivalent zero flux and error correction method and device

Abstract

The invention discloses an air gap transformer equivalent zero flux and error correction method and device, and the method comprises the steps: constructing a full-parameter traceability algorithm comprising an air gap error, a magnetic error, a capacitive error, a temperature error and a stress error through the basic design of constructing and fusing a broadband current transformer equivalent circuit, a divider resistance equivalent theoretical model and other methods; a single-iron-core double-winding equivalent zero-flux magnetic circuit is designed and compensation is implemented, and an Internet of Things intelligent terminal solution can be expanded. The device adopts a multi-mode iron core structure and a symmetric winding process, an error correction module integrates a multi-theoretical model and an intelligent compensation unit, the problems of design, manufacturing and field use of the air gap mutual inductor are solved, and the measurement precision and stability are improved.

Description

Technical Field

[0001] The present application relates to the field of mutual inductors, and in particular to a method and device for correcting equivalent zero magnetic flux and error of an air-gap mutual inductor. Background Art

[0002] In the field of power system metering and detection, air-gap transformers, as key equipment for on-site current measurement, face core technical bottlenecks stemming from the degradation of accuracy and insufficient stability under complex operating conditions caused by the coupling of multiple error sources. During their design and operation, air-gap transformers face the coupling of multiple error sources, including magnetic field distortion caused by eddy current effects on the air gap end faces, magnetic errors due to core material nonlinearity, capacitive errors introduced by winding parasitic capacitance, and air gap micro-variation errors caused by temperature and stress changes. Traditional single theoretical models or single-parameter compensation methods struggle to effectively correct the entire error chain. Existing technologies for air-gap transformers exhibit significant error fluctuations over a wide frequency band (e.g., from power frequency to high frequency), making them inadequate for wide dynamic range measurements of both micro- and high-current scenarios in weak magnetic fields. Furthermore, errors accumulated in process steps such as core air gap control accuracy, secondary winding uniformity, and resistance matching result in short calibration cycles and high maintenance costs in field applications. Although the existing technology has proposed basic theories such as the equivalent circuit of wide-band current transformer and the equivalent theoretical model of voltage-divider resistor, a complete error correction system integrating multiple theories has not yet been formed, and it is unable to solve the comprehensive problems of accuracy, stability and applicability in the design, manufacturing and field use of air-gap transformers. It is urgently necessary to achieve equivalent zero-flux control and accurate compensation of all error components through error modeling, full-parameter traceability algorithm construction and process optimization through multi-method integration, so as to meet the needs of high-precision and high-reliability transformers in scenarios such as smart grids and new energy monitoring. Summary of the Invention

[0003] The purpose of this application is to provide an air gap mutual inductor equivalent zero flux and error correction method and device to solve the technical problems of short calibration cycle and high maintenance cost in field application of traditional technology.

[0004] In the first aspect, the present application provides an air gap mutual inductor equivalent zero flux and error correction method, comprising the following steps: selecting an iron core material and making an annular or rectangular iron core structure, implementing a winding density enhancement process on the end face of the iron core, completing the secondary winding according to a multi-layer winding method, integrating and constructing a broadband equivalent circuit model, a voltage divider resistor equivalent model, an air gap eddy current model and an active negative impedance model, and integrating and constructing an air gap mutual inductor theoretical model; controlling the double air gap size to a micron-level accuracy range, dividing the sampling resistor into an upper resistance segment and a lower resistance segment, and each segment is further divided into sub-segments and connected to a physical capacitor to form a hardware compensation network, connecting an adjustable resistor in series in the secondary loop to match the detection signal with the sampling signal amplitude and phase, and monitoring the dynamic changes of the air gap through the harmonic initial phase stability; setting the iron core cross-section to be greater than the minimum threshold, configuring a feedback loop with adjustable open-loop gain, matching the secondary loop impedance characteristics in the low frequency band, separating the capacitive error component in the high frequency band, and calculating the magnetic error component in the working frequency band.

[0005] Furthermore, the basic design elements and theoretical models of air-gap transformers are constructed, and multi-modal air-gap transformers covering a variety of core materials, shapes and winding processes are studied. The broadband current transformer equivalent circuit, voltage divider resistor equivalent theoretical model, air-gap eddy current theoretical model and active negative impedance theoretical model are integrated, and a flexible design table including material frequency, magnetic permeability, loss angle characteristics, etc. is constructed to establish a complete error correction theoretical model.

[0006] In one of the embodiments, the multi-layer winding method specifically includes: winding the secondary winding in two layers of unwinding and rewinding on each side of the core; implementing a winding density enhancement process in the area near the end face of the core; and the winding adopts a symmetrical and evenly distributed structure.

[0007] In one embodiment, the integrated model specifically includes: the broadband equivalent circuit model quantifies the capacitive error component caused by the distributed capacitance; the voltage divider resistor equivalent model virtually segments the sampling resistor and converts it into a physical capacitance network; the air gap eddy current model analyzes the magnetic line offset caused by the end face eddy current ring; and the active negative impedance model achieves zeroing of the angular difference by adjusting the adjustable resistor.

[0008] In one embodiment, the construction of the hardware compensation network specifically includes: dividing the upper resistance segment into a first sub-resistance segment and a second sub-resistance segment; dividing the lower resistance segment into a third sub-resistance segment and a fourth sub-resistance segment; connecting a physical capacitor between the connection point between the first sub-resistance segment and the second sub-resistance segment and the connection point between the third sub-resistance segment and the fourth sub-resistance segment; and adjusting the resistance ratio of each sub-resistance segment so that the p-factor of the voltage divider resistor equivalent model approaches zero.

[0009] In one embodiment, the harmonic initial phase stability monitoring specifically includes: collecting the second harmonic component of the secondary winding output signal; calculating the initial phase angle fluctuation range of the second harmonic component; when it is detected that the initial phase angle fluctuation exceeds a preset threshold, determining that the air gap has changed dynamically; triggering the compensation winding to perform real-time correction on the error voltage generated by the slight change in the air gap.

[0010] In one of the embodiments, it also includes constructing a full-parameter traceability algorithm for the air gap mutual inductor, which is used for the parameter design and coil winding process of air gap error research, forming a capacitive error compensation network based on sampling resistors and capacitors, and using second harmonic data recognition technology to dynamically monitor and compensate for the air gap micro-change voltage, and decomposing the error components in the order from high frequency to industrial frequency.

[0011] One embodiment further includes establishing an active negative impedance theoretical model, including steps such as: an active compensation circuit comprising a secondary voltage detector, a power amplifier driver generating a current source to provide a balanced primary ampere-turn, a sampling resistor (also known as a bias or load resistor), and a compensation trimming resistor connected in series with the transformer secondary circuit to form an active negative impedance; an equivalent negative impedance is connected in parallel with the transformer secondary impedance, fully compensating the secondary inductance and causing the angle difference to approach zero. The active compensation transformer ratio and angle difference expressions are: f = -r*sin(ψ+α); δ = r*cos(ψ+α); where r represents the compensated modulus, ψ is the core loss angle, and α is the impedance angle after the trimming resistor is added.

[0012] In a second aspect, the present invention further provides an air gap mutual inductor equivalent zero flux and error correction device, comprising:

[0013] Theoretical integrated construction module: select the core material and make a ring or rectangular core structure, implement the winding density enhancement process on the core end face, complete the secondary winding according to the multi-layer winding method, integrate and construct a broadband equivalent circuit model, a voltage divider resistor equivalent model, an air gap eddy current model and an active negative impedance model, and integrate and construct a theoretical model of an air gap mutual inductor; compensation module: contains a segmented sampling resistor network, a fine-tuning resistor and an active negative impedance power amplifier circuit, which is used to set the core cross-section to be greater than the minimum threshold, configure a feedback loop with adjustable open-loop gain, match the secondary circuit impedance characteristics in the low-frequency band, separate the capacitive error component in the high-frequency band, and calculate the magnetic error component in the working frequency band; Internet of Things module: used to embed the processing chip to perform frequency segment compensation, add auxiliary windings, generate standard current signals through the digital-to-analog conversion unit, and connect the processed data communication to the Internet of Things platform.

[0014] In one embodiment, the error correction module also includes an intelligent expansion module, and the intelligent expansion unit is configured with an ARM chip, a third winding and a data communication module, which is used to realize multi-point frequency digital compensation, system self-calibration, data pre-processing and node interconnection with the urban Internet of Things platform.

[0015] Beneficial effects

[0016] This invention significantly improves the comprehensive performance of air-gap transformers through the integration of multiple theoretical models and full-process error control: by collaborating with the broadband current transformer equivalent circuit and the voltage divider resistor model, accurate compensation of the capacitive error component (related to the square and first power of the frequency) is achieved. Combined with active negative impedance technology, the angular difference is brought close to zero, solving the accuracy bottleneck of traditional transformers with a passive accuracy of only 0.5 and an active accuracy of only 0.1. A full-parameter traceability algorithm that includes air gap error, magnetic error, capacitive error, temperature and stress error is constructed, and a "zebra crossing effect" is proposed for air gap end face eddy current interference. Theoretical model, through symmetrical winding, end face density enhancement and other processes, improves the air gap stability by an order of magnitude, effectively suppressing the error fluctuation caused by slight air gap changes; the single core double winding equivalent zero flux design strictly controls the air gap thickness (0.01~0.03mm) and the core cross section (≥0.64cm²), combined with the optimization of the secondary winding turns and wire diameter, so that the residual flux is only the active loss of excitation, achieving a dynamic balance between the ratio difference and the angle difference. Compared with the traditional structure, the measurement range is widened to 1nA~100kA, and the capacitive error compensation accuracy reaches 10 under high-frequency conditions. -15 The IoT smart terminal expansion solution achieves 0.02-level system accuracy and remote calibration functions by embedding ARM chips and third-winding self-calibration technology. The front-end data processing module improves the efficiency of error analysis. Combined with the urban energy node sharing platform, it provides a standardized data source for smart grid monitoring and distributed energy management, and promotes the upgrade of transformers from single measurement devices to terminals with data interconnection and intelligent compensation capabilities, effectively reducing on-site calibration costs and manual maintenance intensity, and meeting the power system's demand for high-precision and high-stability transformers. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0018] Figure 1 A working step diagram of an air-gap mutual inductor equivalent zero flux and error correction method provided by an embodiment of the present invention;

[0019] Figure 2 A schematic diagram of a magnetic circuit of an air-gap mutual inductor provided in an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of a current transformer equivalent circuit provided by an embodiment of the present invention;

[0021] Figure 4 A schematic diagram of an equivalent theoretical model of a voltage divider resistor provided in an embodiment of the present invention;

[0022] Figure 5 A phasor diagram of active magnetic error compensation for a current transformer provided by an embodiment of the present invention;

[0023] Figure 6 A schematic diagram of an urban IoT energy node provided by an embodiment of the present invention;

[0024] Figure 7 A diagram of an air-gap mutual inductor equivalent zero flux and error correction device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0026] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0027] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0028] In the field of power system metering and detection, air-gap transformers, as key equipment for on-site current measurement, face core technical bottlenecks stemming from the degradation of accuracy and insufficient stability under complex operating conditions caused by the coupling of multiple error sources. During their design and operation, air-gap transformers face the coupling of multiple error sources, including magnetic field distortion caused by eddy current effects on the air gap end faces, magnetic errors due to core material nonlinearity, capacitive errors introduced by winding parasitic capacitance, and air gap micro-variation errors caused by temperature and stress changes. Traditional single theoretical models or single-parameter compensation methods struggle to effectively correct the entire error chain. Existing technologies for air-gap transformers exhibit significant error fluctuations over a wide frequency band (e.g., from power frequency to high frequency), making them inadequate for wide dynamic range measurements of both micro- and high-current scenarios in weak magnetic fields. Furthermore, errors accumulated in process steps such as core air gap control accuracy, secondary winding uniformity, and resistance matching result in short calibration cycles and high maintenance costs in field applications. Although the existing technology has proposed basic theories such as the equivalent circuit of wide-band current transformer and the equivalent theoretical model of voltage-divider resistor, a complete error correction system integrating multiple theories has not yet been formed, and it is unable to solve the comprehensive problems of accuracy, stability and applicability in the design, manufacturing and field use of air-gap transformers. It is urgently necessary to achieve equivalent zero-flux control and accurate compensation of all error components through error modeling, full-parameter traceability algorithm construction and process optimization through multi-method integration, so as to meet the needs of high-precision and high-reliability transformers in scenarios such as smart grids and new energy monitoring.

[0029] The purpose of this application is to provide an air gap mutual inductor equivalent zero flux and error correction method and device to solve the technical problems of short calibration cycle and high maintenance cost in field application of traditional technology.

[0030] The present application provides an air-gap mutual inductor equivalent zero flux and error correction method, comprising the following steps: selecting an iron core material and manufacturing an annular or rectangular iron core structure, implementing a winding density enhancement process on the iron core end face, completing the secondary winding according to a multi-layer winding method, integrating and constructing a broadband equivalent circuit model, a voltage divider resistor equivalent model, an air gap eddy current model and an active negative impedance model, and fusing and constructing an air-gap mutual inductor theoretical model; controlling the size of the double air gap to a micron-level accuracy range, dividing the sampling resistor into an upper resistance segment and a lower resistance segment, each segment is further divided into sub-segments and connected to a physical capacitor to form a hardware compensation network, connecting an adjustable resistor in series in the secondary loop to match the amplitude and phase of the detection signal and the sampling signal, and monitoring the dynamic change of the air gap through the initial phase stability of the harmonic; setting the iron core cross-section to be greater than the minimum threshold, configuring a feedback loop with adjustable open-loop gain, matching the secondary loop impedance characteristics in the low-frequency band, separating the capacitive error component in the high-frequency band, and calculating the magnetic error component in the power frequency band.

[0031] Example 1

[0032] refer to Figure 1-Figure 5The present application provides a method for correcting an equivalent zero flux level error of an air gap mutual inductor, comprising the following steps:

[0033] S110. Select an iron core material and manufacture an annular or rectangular iron core structure. Implement a winding density enhancement process on the iron core end face. Complete the secondary winding using a multi-layer winding method. Integratedly construct a broadband equivalent circuit model, a voltage divider resistance equivalent model, an air gap eddy current model, and an active negative impedance model. Integrate and construct an air gap mutual inductor theoretical model.

[0034] S120: Control the dual air gap size to a micron-level precision range. The sampling resistor is divided into an upper resistance segment and a lower resistance segment. Each segment is further divided into sub-segments and connected to physical capacitors to form a hardware compensation network. An adjustable resistor is connected in series with the secondary loop to ensure that the detection signal and the sampling signal amplitude and phase match. The dynamic change of the air gap is monitored through the initial phase stability of the harmonics.

[0035] S130: Set the core cross-section to be larger than the minimum threshold, configure a feedback loop with adjustable open-loop gain, match the secondary circuit impedance characteristics in the low-frequency band, separate the capacitive error component in the high-frequency band, and calculate the magnetic error component in the power frequency band.

[0036] It should be noted that, referring to Table 1, the flexible design table for constructing air gap mutual inductor includes material, frequency, magnetic permeability, loss angle characteristics and other process methods: the target core magnetic circuit calculation table magnetic density, magnetic field strength lower limit is extended to 3×10 -7 (Gs), 3×10 -12 (A / cm), expressed as the rate of decrease of magnetic permeability per decade relative to the power frequency reference value (determined by actual measurement, about 2~3, the power frequency is a reference coefficient of 1, which can be fine-tuned), the loss angle coefficient is the difference caused by the manufacturing process of different core materials (standard coefficient 1, which can be fine-tuned), and the eddy current coefficient is an estimated value of the leakage reactance characteristics specific to the secondary circuit of the air-gap transformer (standard coefficient 1, which can be fine-tuned).

[0037] Magnetic error calculation: e m =Y m *Z2;e m is the magnetic error; Y m is the excitation admittance; Z2 is the total impedance of the secondary circuit; R t is the core loss; L m is the core magnetizing inductance; R2 is the DC resistance of the secondary circuit; L 2s is the secondary circuit leakage reactance:

[0038] Y m =1 / (R t +j*ω*L m )=(R t -j*ω*L m ) / (R t ^2+ω^2*L m^2)=R t / (r m ^2)-j*ω*L m / (r m ^2)

[0039] Y m *Z2=(R t *R2-ω^2*L m *L 2s ) / r m ^2 +j*ω*(R t *L 2s + R2*L m ) / r m ^2);

[0040] r m ^2~=ω^2*L m ^2;

[0041] R t *R2<<ω^2*L m *L 2s ;

[0042] R t < <L m ; Y m *Z2≈-L 2s / L m +j*(R2 / (ω*L m );

[0043] The first term in the approximate formula is the main term of the ratio difference. The error increases slowly with the increase of frequency because L m Since the magnetic permeability of the iron core µ r The decrease results in a decrease of about 2 to 3 times per decade (measured data), while the leakage reactance L 2s The magnetic permeability of air, µ0, is frequency invariant. The second term in the approximate formula is the main term of the angular difference, which decreases rapidly with increasing frequency.

[0044] The test sample parameters are as follows: A1 asymmetrically wound secondary coil, alloy stacking, secondary resistor and sampling resistor weakly matched; A2 post-segmented symmetrically wound secondary coil, alloy stacking, secondary resistor and sampling resistor mismatched; A3 annular symmetrical winding with end face density, alloy winding, secondary resistor and adjustment resistor strongly matched; B1 annular asymmetrically wound secondary coil, silicon steel winding, secondary resistor mismatched; B2 annular symmetrical winding with end face density, microcrystalline winding, secondary resistor and fine-tuning resistor strongly matched. C1 annular symmetrical winding with end face density, silicon steel winding, secondary resistor and fine-tuning resistor strongly matched, sample air gaps of 13mm and 30mm are used.

[0045] Based on the research and experiments on air gap errors, we proposed parameter design and coil winding process methods, which improved the air gap stability by an order of magnitude compared to the original product. See Table 1-1 to Table 1-11:

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057] Step S110 also includes constructing the basic design elements and theoretical models of air-gap mutual inductors, studying multi-modal air-gap mutual inductors covering a variety of core materials, shapes, and winding processes, integrating the broadband current mutual inductor equivalent circuit, the voltage divider resistor equivalent theoretical model, the air-gap eddy current theoretical model, and the active negative impedance theoretical model, and constructing a flexible design table containing material frequency, magnetic permeability, loss angle characteristics, etc. to establish a complete error correction theoretical model. The integrated model specifically includes: the broadband equivalent circuit model quantifies the capacitive error component caused by distributed capacitance; the voltage divider resistor equivalent model virtually segments the sampling resistor and converts it into a physical capacitor network; the air-gap eddy current model analyzes the magnetic field line offset caused by the end face eddy current ring; and the active negative impedance model achieves zero angular error by adjusting the adjustable resistor. The multi-layer winding method specifically includes: winding the secondary winding using two layers of unwinding and rewinding on each side of the core; implementing a winding density enhancement process in the area near the core end face; and adopting a symmetrical and uniformly distributed winding structure.

[0058] In one embodiment, the construction of the hardware compensation network specifically includes: dividing the upper resistance segment into a first sub-resistance segment and a second sub-resistance segment; dividing the lower resistance segment into a third sub-resistance segment and a fourth sub-resistance segment; connecting a physical capacitor between the connection point between the first sub-resistance segment and the second sub-resistance segment and the connection point between the third sub-resistance segment and the fourth sub-resistance segment; and adjusting the resistance ratio of each sub-resistance segment so that the p-factor of the voltage divider resistor equivalent model approaches zero.

[0059] In one embodiment, the harmonic initial phase stability monitoring specifically includes: collecting the second harmonic component of the secondary winding output signal; calculating the initial phase angle fluctuation range of the second harmonic component; when it is detected that the initial phase angle fluctuation exceeds a preset threshold, determining that the air gap has changed dynamically; triggering the compensation winding to perform real-time correction on the error voltage generated by the slight change in the air gap.

[0060] In one of the embodiments, it also includes constructing a full-parameter traceability algorithm for the air gap mutual inductor, which is used for the parameter design and coil winding process of air gap error research, forming a capacitive error compensation network based on sampling resistors and capacitors, and using second harmonic data recognition technology to dynamically monitor and compensate for the air gap micro-change voltage, and decomposing the error components in the order from high frequency to industrial frequency.

[0061] One embodiment further includes establishing an active negative impedance theoretical model, including steps such as: an active compensation circuit comprising a secondary voltage detector, a power amplifier driver generating a current source to provide a balanced primary ampere-turn, a sampling resistor (also known as a bias or load resistor), and a compensation trimming resistor connected in series with the transformer secondary circuit to form an active negative impedance; an equivalent negative impedance is connected in parallel with the transformer secondary impedance, fully compensating the secondary inductance and causing the angle difference to approach zero. The active compensation transformer ratio and angle difference expressions are: f = -r*sin(ψ+α); δ = r*cos(ψ+α); where r represents the compensated modulus, ψ is the core loss angle, and α is the impedance angle after the trimming resistor is added.

[0062] It should be noted that under active compensation conditions, this embodiment establishes a static detection and compensation method for secondary winding leakage reactance. Specifically, a fine-tuning resistor is added to equalize the detected electromotive force of the detection input with the sampling resistor voltage, resulting in an angular error compensation better than 0.001% at the power frequency. The residual magnetic flux that maintains the stability of the feedback loop is the active excitation loss. The compensation winding and electronic circuitry fully compensate for the subsequent magnetic errors. The sampling resistor is divided into upper and lower resistors, each of which is divided into two sections and forms a capacitive error compensation network with the connected capacitor. Using a voltage divider resistor equivalent theoretical model, the virtual resistors and capacitors are converted into physical non-inductive resistors and capacitors. Single calibration constant error compensation is simulated for wideband frequency K-factor measurements. If an ARM intelligent module is embedded, the hardware compensation network is modified to use multiple calibration constants for audio sinusoidal hardware compensation (digital potentiometer) or digital compensation of harmonics with the power frequency as the fundamental wave.

[0063] refer to Figure 4 In this embodiment, the voltage-dividing resistor equivalent theoretical model includes: voltage-dividing resistor equivalent theoretical model voltage-dividing resistor equivalent theoretical model formula:

[0064] e c =k f *ω^2+j*k t *ω;

[0065] Among them: K f =-T^2*p*(R 11 +R 22 ) / (R2*(R1+R2)^2);

[0066] K t =T*p / (R2+(R1+R2));

[0067] T=C*(R 11 +R 21 );T is the time constant; p=R 21 *R 11 -R 22 *R 12 ; p is a factor.

[0068] R1 and R2 are the upper and lower physical resistances of the equivalent voltage divider resistor respectively. 11 、R 12 The upper resistor is virtually segmented, R 21 、R 22 The lower resistor is virtually segmented and connected to a virtual equivalent capacitor to verify the theoretical model with the traceability data of the harmonic reference voltage divider resistor 50V~400V of the China National Institute of Metrology at 40Hz~3000Hz. f The value is about 1×10 -15 , which is determined by the resistance parameters, shielding structure parameters and air medium, is a constant that does not change with frequency. In the range of 50Hz-3kHz, the agreement between theoretical calculation and simplified calculation is about 1×10 -20 .K t The value is about 1×10 -7 , which is determined by the resistance parameters, shielding structure parameters and air medium, is a constant that does not change with frequency. In the range of 50Hz-3kHz, the agreement between theoretical calculation and simplified calculation is about 1×10 -14 When p=0, no matter how the frequency and equivalent capacitance change, the proportional error and angle difference of the voltage divider are zero. When p<0, the proportional error of the voltage divider is positive and its absolute value increases with the frequency. 2 The angle difference is negative and its absolute value increases with the frequency. When p>0, the proportional error of the voltage divider is negative and its absolute value increases with the frequency. 2 The angular difference is positive and its absolute value increases with the frequency in a ω-like relationship. Kf , K t are the amplitude and phase shift calculation constants of the equivalent theoretical model respectively. Term a and term b are very similar and the latter gives K f and K t Obviously, by clustering the theoretical model of the 100V~400V voltage divider resistor with the transformer secondary sampling resistor, we can obtain an excellent passive compensation network with changeable transformer compensation direction, amplitude error component, and phase shift component.

[0069] Furthermore, in step S120, it also includes constructing a magnetic circuit with an air gap single iron core double winding equivalent zero flux method and implementing traceability compensation working steps:

[0070] S1201: The double air gap in the core is controlled between 0.01 and 0.03 mm. The inspection process uses the measured error data from the sample to determine whether the control parameters meet the standards. This is because the impact of air gap changes far outweighs the impact of material permeability differences. It should be noted that when the air gap exceeds 0.1 mm, the air gap error stabilization time increases significantly, which introduces uncertainty in field use.

[0071] S1202, core cross section>=0.64cm 2 The leakage magnetic area ratio at the air gap end face decreases as the end face increases. The secondary winding turns are set to 1000, and the secondary inter-turn capacitance can be easily measured. This model determines the capacitive error caused by the secondary winding inter-turn capacitance, where the difference component is proportional to the square of the signal frequency and the angle difference component is proportional to the first power of the signal. Furthermore, this model is used to compensate for the power amplifier's drive capability limitations.

[0072] S1203, Material Processing - The DC resistance of the secondary winding plus the circuit fine-tuning compensation resistor must be strictly matched with the sampling resistor. Mismatch causes the feedback loop to produce under-compensated crossover distortion or over-compensated distortion. Theoretical derivation proves that there is a stable minimum point.

[0073] S1204, the sampling resistor is based on the secondary current size and the matching and power consumption of the back-end AD sampling rated voltage. The detection process - if the sampling voltage is 1V and the secondary current is 0.1A, the sampling resistor is designed to be 12 ohms, of which the upper resistor is 2 ohms and the lower resistor is 10 ohms. A capacitor is inserted between the connection points of the upper and lower resistor sub-resistance segments to form a hardware compensation network. The power supply is ±8V, which is more than half the power amplifier loss of the ordinary ±15V.

[0074] S1205, open-loop gain 200~500, loop gain, phase shift frequency characteristics low frequency band adaptation secondary impedance angle.

[0075]

[0076] Note: This table is for passive transformer calculations. The calculated air gap is 0.013mm. Since the air gap error sensitivity is 1 to 2 orders of magnitude greater than other parameters, a process indicator can be set for comparison with the measured data.

[0077] Example 2,

[0078] See also Figure 6-Figure 7 In the second aspect, the present invention also provides an air-gap mutual inductor equivalent zero flux and error correction device, including: a theoretical integrated construction module: selecting an iron core material and making an annular or rectangular iron core structure, implementing a winding density enhancement process on the end face of the iron core, completing the secondary winding according to a multi-layer winding method, integrating and constructing a broadband equivalent circuit model, a voltage divider resistor equivalent model, an air gap eddy current model and an active negative impedance model, and integrating and constructing an air-gap mutual inductor theoretical model; a compensation module: containing a segmented sampling resistor network, a fine-tuning resistor and an active negative impedance power amplifier circuit, used to set the iron core cross-section to be greater than the minimum threshold, configuring a feedback loop with adjustable open-loop gain, matching the secondary loop impedance characteristics in the low-frequency band, separating the capacitive error component in the high-frequency band, and calculating the magnetic error component in the working frequency band; an Internet of Things module: used to embed a processing chip to perform frequency segmented compensation, add an auxiliary winding, generate a standard current signal through a digital-to-analog conversion unit, and connect the processed data communication to the Internet of Things platform.

[0079] In one embodiment, the error correction module also includes an intelligent expansion module equipped with an ARM chip, a tertiary winding, and a data communication module. This intelligent expansion module is used to implement multi-point frequency digital compensation, system self-calibration, data pre-processing, and node interconnection with the city's Internet of Things platform. The ARM chip is embedded with multi-point frequency digital compensation or K-factor compensation for digital-to-analog conversion. This achieves a high-precision correction formula for segmented frequency parameters, where the ratio difference of capacitive error is approximately equal to the square of the signal frequency and the angular error is approximately equal to the first power of the signal, and allows for remote calibration. A 100-turn tertiary winding is introduced, and the DA within the expansion module generates a standard 0.01A current signal for system self-calibration, improving system accuracy to 0.02. The pre-positioned data processing module is efficient, fast, and convenient. This provides a reliable data source for artificial intelligence research. It serves as a shared platform node for city safety supervision departments, universities, research institutes, and related enterprises, particularly in urban rail transit, urban pipeline corridors, and distributed energy resources.

[0080] An embodiment of the present application also provides a storage medium containing computer-executable instructions, which, when executed by a computer processor, are used to execute various air-gap mutual inductor equivalent zero flux and error correction methods, including the following steps: selecting an iron core material and making an annular or rectangular iron core structure, implementing a winding density enhancement process on the end face of the iron core, completing the secondary winding according to a multi-layer winding method, integrating and constructing a broadband equivalent circuit model, a voltage divider resistor equivalent model, an air gap eddy current model and an active negative impedance model, and fusing and constructing an air-gap mutual inductor theoretical model; controlling the size of the double air gap to a micron-level accuracy range, dividing the sampling resistor into an upper resistance segment and a lower resistance segment, each segment is further divided into sub-segments and connected to a physical capacitor to form a hardware compensation network, connecting an adjustable resistor in series in the secondary loop to match the amplitude and phase of the detection signal and the sampling signal, and monitoring the dynamic change of the air gap through the initial phase stability of the harmonic; setting the iron core cross-section to be greater than a minimum threshold, configuring a feedback loop with adjustable open-loop gain, matching the secondary loop impedance characteristics in the low-frequency band, separating the capacitive error component in the high-frequency band, and calculating the magnetic error component in the power frequency band.

[0081] Storage medium—any of various types of memory devices or storage devices. The term "storage medium" is intended to include: installation media, such as CD-ROMs, floppy disks, or tape drives; computer system memory or random access memory, such as DRAM, DDR RAM, SRAM, EDO RAM, and Rambus RAM; non-volatile memory, such as flash memory, magnetic media (e.g., hard disks or optical storage); registers or other similar types of memory elements; and the like. Storage media may also include other types of memory or a combination thereof. Furthermore, a storage medium may be located in a first computer system where a program is executed, or in a different second computer system connected to the first computer system via a network (such as the Internet). The second computer system may provide program instructions to the first computer system for execution. The term "storage medium" may include two or more storage media residing in different locations (e.g., in different computer systems connected via a network). A storage medium may store program instructions (e.g., embodied as a computer program) that are executable by one or more processors.

[0082] Of course, the storage medium containing computer-executable instructions provided in an embodiment of the present application is not limited to the above-mentioned air gap mutual inductor equivalent zero magnetic flux and error correction method, and can also execute the relevant operations in the air gap mutual inductor equivalent zero magnetic flux and error correction method provided in any embodiment of the present application.

[0083] The air gap mutual inductor equivalent zero flux and error correction method and device provided in the above embodiments can execute the air gap mutual inductor equivalent zero flux and error correction method provided in any embodiment of the present application. For technical details not described in detail in the above embodiments, please refer to the air gap mutual inductor equivalent zero flux and error correction method provided in any embodiment of the present application.

[0084] The present invention provides an air-gap current transformer equivalent zero flux and error correction method and device. Through the fusion of multiple theoretical models and full-process error control, the comprehensive performance of the air-gap current transformer is significantly improved: through the collaboration of the broadband current transformer equivalent circuit and the voltage divider resistor model, accurate compensation of the capacitive error component is achieved, and combined with active negative impedance technology, the error is brought close to zero, breaking through the accuracy limitations commonly seen in traditional technologies; a full-parameter tracing algorithm including air gap error, magnetic error, capacitive error, temperature and stress error is constructed, and a "zebra crossing effect" is proposed for air gap end face eddy current interference. The theoretical model improves the air gap stability through symmetrical winding, end face density enhancement and other processes, effectively suppressing the error fluctuation caused by slight changes in the air gap; the single-core double-winding equivalent zero flux design strictly controls the air gap thickness and core cross-sectional dimensions, combined with the optimization of the secondary winding turns and wire diameter, so that the residual flux is only the active loss of excitation, achieving a dynamic balance between the ratio difference and the angle difference, widening the measurement range compared to the traditional structure, and achieving extremely high-precision capacitive error compensation under high-frequency conditions; the IoT smart terminal expansion solution achieves higher system accuracy and remote calibration functions by embedding smart chips and third-winding self-calibration technology. The front-end data processing module improves the error analysis efficiency, and combined with the urban energy node sharing platform, it provides a standardized data source for smart grid monitoring and distributed energy management, and promotes the upgrade of transformers from single measurement equipment to terminals with data interconnection and intelligent compensation capabilities, effectively reducing on-site calibration costs and manual maintenance intensity, and meeting the power system's demand for high-precision and high-stability transformers.

[0085] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for equivalent zero magnetic flux and error correction of an air gap mutual inductor, characterized in that: The following steps are involved: Select the core material and make a ring or rectangular core structure. Implement a winding density enhancement process on the core end face. Complete the secondary winding according to the multi-layer winding method. Integrate and construct a broadband equivalent circuit model, a voltage divider resistance equivalent model, an air gap eddy current model, and an active negative impedance model to construct a theoretical model of the air gap mutual inductor. The dual air gap size is controlled to micron-level accuracy. The sampling resistor is divided into an upper resistance segment and a lower resistance segment. Each segment is further divided into sub-segments and connected to physical capacitors to form a hardware compensation network. An adjustable resistor is connected in series with the secondary loop to match the amplitude and phase of the detection signal and the sampling signal. The dynamic change of the air gap is monitored through the initial phase stability of the harmonics. The core cross-section is set to be larger than the minimum threshold, and a feedback loop with adjustable open-loop gain is configured. The secondary circuit impedance characteristics are matched in the low-frequency band, the capacitive error component is separated in the high-frequency band, and the magnetic error component is calculated in the power frequency band.

2. The air gap mutual inductor equivalent zero flux and error correction method according to claim 1, characterized in that: It also includes that the multi-layer winding method specifically includes: winding the secondary winding in two layers of unwinding and rewinding on each side of the iron core; implementing a winding density enhancement process in the area near the end face of the iron core; and the winding adopts a symmetrical and evenly distributed structure.

3. The air gap mutual inductor equivalent zero flux and error correction method according to claim 1, characterized in that: The integrated model specifically includes: The broadband equivalent circuit model quantifies the capacitive error component caused by distributed capacitance; The voltage divider resistor equivalent model virtually segments the sampling resistor and converts it into a physical capacitor network; The air gap eddy current model analyzes the magnetic field line deviation caused by the end face eddy current ring; The active negative impedance model realizes zeroing of the angle difference by adjusting the adjustable resistor.

4. The air gap mutual inductor equivalent zero flux and error correction method according to claim 1, characterized in that: The hardware compensation network construction specifically includes: dividing the upper resistance segment into a first sub-resistance segment and a second sub-resistance segment; dividing the lower resistance segment into a third sub-resistance segment and a fourth sub-resistance segment; Connecting a physical capacitor between a dividing point between the first resistance sub-segment and the second resistance sub-segment and a dividing point between the third resistance sub-segment and the fourth resistance sub-segment; The p-factor of the voltage divider resistor equivalent model is made close to zero by adjusting the resistance ratio of each sub-resistance segment.

5. The air gap mutual inductor equivalent zero flux and error correction method according to claim 1, characterized in that: The harmonic initial phase stability monitoring specifically includes: collecting the second harmonic component of the secondary winding output signal; calculating the initial phase angle fluctuation range of the second harmonic component; when it is detected that the initial phase angle fluctuation exceeds a preset threshold, determining that the air gap has changed dynamically; triggering the compensation winding to perform real-time correction on the error voltage caused by the slight change in the air gap.

6. The air gap mutual inductor equivalent zero flux and error correction method according to claim 1, characterized in that: It also includes building a full-parameter traceability algorithm for air gap mutual inductor, which is used for air gap error research parameter design and coil winding process, forming a capacitive error compensation network based on sampling resistors and capacitors, using second harmonic data recognition technology to dynamically monitor and compensate for the air gap micro-change voltage, and decomposing the error components in the order from high frequency to industrial frequency.

7. The air gap mutual inductor equivalent zero flux and error correction method according to claim 1, characterized in that: It also includes establishing an active negative impedance theoretical model, and the steps of establishing the model include: The active compensation circuit includes detecting the secondary voltage, a power amplifier driver to generate a current source to provide a balanced primary ampere-turn, a sampling resistor also called a bias or load resistor, and a compensation trimming resistor connected in series with the transformer secondary circuit to form an active negative impedance. The equivalent negative impedance is connected in parallel with the transformer secondary impedance, and the secondary inductance is fully compensated, causing the angle difference to approach zero. The active compensation transformer ratio difference and angle difference expression are: f=-r*sin(ψ+α); δ=r*cos(ψ+α); Where: r represents the modulus after compensation, ψ is the core loss angle, and α is the impedance angle with the fine-tuning resistor added.

8. An air gap mutual inductor equivalent zero flux and error correction device, characterized in that: include: Theoretical integrated construction module: Select the core material and make a ring or rectangular core structure, implement a winding density enhancement process on the core end face, complete the secondary winding according to the multi-layer winding method, integrate and construct a broadband equivalent circuit model, a voltage divider resistance equivalent model, an air gap eddy current model and an active negative impedance model, and integrate and construct a theoretical model of the air gap mutual inductor; Compensation module: Contains a segmented sampling resistor network, fine-tuning resistors, and an active negative impedance amplifier circuit. It is used to set the core cross-section to be greater than the minimum threshold, configures a feedback loop with adjustable open-loop gain, matches the secondary circuit impedance characteristics in the low-frequency band, separates the capacitive error component in the high-frequency band, and calculates the magnetic error component in the power frequency band. IoT module: used to embed a processing chip to perform frequency segmentation compensation, add an auxiliary winding, generate a standard current signal through a digital-to-analog conversion unit, and connect the processed data communication to the IoT platform.

9. The air gap mutual inductor equivalent zero flux and error correction device according to claim 8, characterized in that: The error correction module also includes an intelligent expansion module. The intelligent expansion unit is configured with an ARM chip, a third winding and a data communication module, which is used to realize multi-point frequency digital compensation, system self-calibration, data pre-processing and node interconnection with the urban Internet of Things platform.

10. A storage medium containing computer-executable instructions, characterized in that: When executed by a computer processor, the computer executable instructions are used to execute an air-gap mutual inductor equivalent zero flux and error correction method as described in any one of claims 1 to 7.

Images