Flexible Rogowski coil current sensor and measuring method

Abstract

The invention discloses a flexible Rogowski coil current sensor and a measuring method. The sensor comprises a shell, a main coil and a connector module, and is characterized in that an I-shaped framework cylinder with a compensation winding is arranged in the shell, and the framework cylinder is sleeved on the periphery of an interface gap formed by butt joint of a fixed end and a movable end of the main coil. The compensation winding and the main winding are connected in series and then are connected to the integral circuit, additional electromotive force is generated through residual magnetic flux at the induction gap, and signal loss caused by discontinuous structures is compensated. The measurement method comprises the steps of determining compensation parameters, arranging a compensation winding, performing electrical connection and establishing a mathematical model through self-calibration to calibrate output. Through combination of structure compensation and algorithm calibration, measurement errors at the joint of the open type Rogowski coil are effectively eliminated, and the open type Rogowski coil has the advantages of being high in precision, compact in structure and high in adaptability.

Description

Technical Field

[0001] This application relates to the field of current measurement and sensing technology, specifically to a flexible Rogowski coil current sensor and measurement method. Background Technology

[0002] A Rogowski coil is a current sensor based on the principle of electromagnetic induction. It has advantages such as a wide measurement range, wide bandwidth, no magnetic saturation, and isolation from the circuit under test. It is widely used in power systems, industrial control, and pulse current measurement.

[0003] To facilitate installation without cutting the wires, flexible open-type Rogowski coils were developed. However, this open structure inevitably creates a blank area at the joint, resulting in uneven magnetic flux distribution in this area and introducing significant measurement errors, typically several percentage points. This error varies depending on the position of the conductor being measured within the coil, severely affecting the accuracy and consistency of the measurement.

[0004] In the prior art, there are several solutions that attempt to compensate for this error. For example, some solutions add a magnetic core or a partial shielding structure at the joint, but these methods have limited compensation effects and lead to structural complexity, increased cost, and inconvenient installation. Other solutions attempt to reduce the error through precise initial winding, but cannot solve the performance drift problem caused by material aging, temperature changes, and mechanical stress during use. Therefore, there is an urgent need in the field for a technical solution that can effectively compensate for the opening error in principle while maintaining measurement accuracy. Summary of the Invention

[0005] The purpose of this invention is to overcome the aforementioned deficiencies of the prior art and provide a flexible Rogowski coil current sensor and measurement method. This method and device not only compensate for inherent magnetic flux defects at the connector through structural design, but also calibrate the final output through a self-calibration function, thereby achieving high-precision and high-stability current measurement.

[0006] To achieve the above objectives, this application adopts the following technical solution: On one hand, the present invention provides a flexible Rogowski coil current sensor, comprising a housing, a main coil, a connector module, and a circuit board assembled within the housing; the main coil includes a flexible non-magnetic core and a main winding wound around the flexible non-magnetic core, the fixed end of the main coil is fixed inside the housing and electrically connected to the circuit board, and its movable end is connected to the housing in an open-closed manner through the connector module; the connector module includes a mechanical connector disposed at the movable end of the main coil and a connector base disposed on one side of the housing; characterized in that: The current sensor also includes an I-shaped skeleton cylinder and a compensation winding disposed within the housing; the I-shaped skeleton cylinder is engaged inside the housing and sleeved around the interface gap formed by the docking of the fixed end and the movable end of the main coil; the compensation winding is wound around the periphery of the I-shaped skeleton cylinder, and its axial width is greater than the width of the interface gap between the fixed end and the movable end of the main coil; the connector base is a through-hole structure, and its inner diameter is greater than the outer diameter of the mechanical connector; The interior of the housing is provided with a stop surface composed of raised ribs corresponding to the installation position of the I-shaped skeleton tube; when the I-shaped skeleton tube is installed in place, its end face will fit tightly against this support plane, providing axial limiting function for the I-shaped skeleton tube.

[0007] The compensation winding is connected in series with the main winding to form a composite induction unit, and the output terminal of the composite induction unit is electrically connected to the circuit board.

[0008] When the main coil is closed, the magnetic flux path at the interface gap is interrupted, causing the magnetic induction intensity in that area to be lower than that of the continuous part of the coil. The compensation winding generates an additional induced electromotive force by coupling the residual magnetic flux in this area. By superimposing this electromotive force in series with the electromotive force of the main winding, the signal loss caused by the structural discontinuity is compensated at the signal level. The axial width of the compensation winding is greater than the physical length of the interface gap in order to ensure that it can fully cover the affected edge magnetic field areas on both sides of the gap, so as to achieve more complete compensation.

[0009] Furthermore, the circuit board is provided with an integrating circuit and a signal processing unit. The output terminal of the composite sensing unit is electrically connected to the input terminal of the integrating circuit, and the output terminal of the integrating circuit is electrically connected to the input terminal of the signal processing unit.

[0010] The induced voltage of the Rogowski coil is proportional to the rate of change of the measured current. The voltage signal can be converted into a DC or low-frequency AC signal proportional to the amplitude of the measured current through an integrating circuit, which is convenient for subsequent measuring equipment to read. Furthermore, the I-shaped skeleton tube includes a first receiving cavity and a second receiving cavity, and the fixed end of the main coil extends into the first receiving cavity and is fixed therein.

[0011] The I-shaped skeleton cylinder ensures that when the main coil is closed, its fixed end and movable end can be precisely aligned and enter the predetermined position inside the I-shaped cylindrical part, so that the interface gap is accurately covered by the compensation winding; the second receiving cavity provides a guiding and receiving space for the mechanical joint, which improves the smoothness of the opening and closing connection and the structural stability after closure, and avoids additional measurement errors caused by joint shaking.

[0012] Furthermore, the mechanical connector includes an engaging portion and a receiving chamber that engage with the connector base, wherein the flexible non-magnetic wire core and the end of the main winding are fixed inside the receiving chamber; the outer diameter of the receiving chamber is smaller than the outer diameter of the engaging portion and the inner diameter of the second receiving cavity; the mechanical connector is movably connected to the connector base and can be embedded in the second receiving cavity.

[0013] On the other hand, the present invention provides a measurement method based on a flexible Rogowski coil, the method comprising the following steps: S1: Determine the compensation parameters: The compensation parameters include the target number of turns of the compensation winding and the axial width of the coil; wherein, the target number of turns N is calculated by the formula N=k×n×L; where n is the number of turns per unit length of the main winding, L is the length of the blank area of ​​the connector, k is a correction coefficient between 0.8 and 1.2, and the axial width of the compensation winding is configured to be greater than the axial length of the interface gap between the fixed end and the movable end after the main coil is engaged; The theoretical ideal value of the correction coefficient is k=1. However, due to factors such as the actual edge magnetic field effect, differences in mutual inductance between windings, and manufacturing tolerances, the optimal compensation point will fluctuate around the theoretical value. The presence of the edge magnetic field makes the effective compensation area larger than the physical gap, and factors such as mutual inductance between windings also affect the compensation effect. By setting the k value between 0.8 and 1.2 and fine-tuning it under standard current, the optimal compensation point for a specific coil structure can be found, minimizing measurement errors. This quantitative design method avoids the blindness of relying on experience in winding in existing technologies.

[0014] S2: Arrangement of compensation winding: An I-shaped skeleton tube is set around the interface gap, and the compensation winding is wound around the I-shaped skeleton tube. The winding direction of the compensation winding is configured so that the direction of its induced electromotive force is consistent with the direction of the electromotive force induced by the main winding in the continuous part. This arrangement enables the compensation winding to effectively couple the magnetic flux in the blank area of ​​the connector, and to perform additive compensation on the signal of the main winding through the correct electromotive force direction, rather than subtractive cancellation. S3: Electrical Connection and Signal Integration: The compensation winding and the main winding are connected in series to form a composite induction unit. The output of the composite induction unit is connected to the integrator circuit. The series connection between the compensation winding and the main winding allows the induction signals of the main winding and the compensation winding to be directly superimposed and input into the subsequent integrator circuit, avoiding signal shunting loss caused by parallel connection and ensuring effective utilization of the compensation signal. At the same time, the series structure simplifies the circuit connection and reduces the interference of distributed parameters on the signal. S4: Self-calibration step, the main coil is wrapped around the periphery of a conductor carrying a known standard current, and the movable end of the main coil is connected to the housing; based on the difference between the output signal of the integrator circuit and the corresponding theoretical expected value, the final output of the composite sensing unit is calibrated by establishing a mathematical relationship model between the measured signal and the standard value.

[0015] Furthermore, the establishment of the mathematical relationship model between the measurement signal and the standard value in step S4 includes the following steps: S41: Data Acquisition: Obtain m different known standard currents and their corresponding integrator circuit output voltages to form a data point set {( , ),( , ),…,( , )}; S42: Using a polynomial fitting algorithm, establish a calibration current value with the output voltage V as the independent variable. The interpolation polynomial function for the dependent variable: Where k is the order of the polynomial (0 < k ... <k≤m), , ... The coefficients are determined through fitting; S43: Real-time calibration: During subsequent measurements, the voltage value output by the integrating circuit in real time will be used for calibration. Substituting the given relationship, the calibrated current value is calculated and output in real time. ( ).

[0016] Furthermore, the range of values ​​for the m different known standard currents covers the expected range of the current to be measured in the practical application of the flexible Rogowski coil device.

[0017] The establishment of the mathematical relationship model between the measurement signal and the standard value in step S4 can also be achieved through the following steps: S41: Data Acquisition: Acquire m calibration data points, each data point including the measured value of the Rogowski coil induced voltage. and the corresponding theoretical voltage value where i = 1, 2, ..., m; S42: Difference Calculation: Calculate the voltage difference at each calibration point. ; S43: Interpolation Model Construction: Based on Lagrange interpolation, a model is constructed using induced voltage. As the independent variable, the voltage calibration value is used. The interpolation polynomial for the dependent variable: in, Let the expression be a Lagrange polynomial, and its expression be: S44: For the Rogowski coil induced voltage measured in real time Calculate its calibrated voltage value: .

[0018] Furthermore, the theoretical voltage value The theoretical transfer function of the standard current source and Rogowski coil is calculated; the number of calibration data points m is at least 3, and the voltage measurement value of the calibration data points is... It covers the expected voltage range in actual measurements.

[0019] Furthermore, the method also includes an iterative calibration step: taking the voltage value after the first calibration... As a new measurement, the above process of calculating the difference and constructing the interpolation model is repeated, and multiple iterations of calibration are performed until the difference between at least two consecutive calibration results is less than a preset threshold. Through several iterations, the systematic residual error can be quickly converged to a negligible level.

[0020] Compared with the prior art, the beneficial effects of this application are: 1. Dual compensation mechanism: The interface gap is structurally and statically compensated by the compensation winding, and the system error is dynamically compensated by the self-calibration algorithm. This fundamentally eliminates the inherent error caused by the open structure and effectively suppresses temperature drift and time drift, achieving a balance between high precision and long-term stability.

[0021] 2. Intelligent adaptive calibration: The built-in self-calibration system can automatically establish an accurate mathematical relationship model based on the known standard current, enabling the sensor to have the ability to learn and correct itself without manual intervention or complex external equipment, which significantly improves the convenience and reliability of use.

[0022] 3. Compact structure and integrated design: The I-shaped cylindrical component, compensation winding, and signal processing circuit are highly integrated into the housing and connector module, forming a compact and mechanically precise integrated measuring device. While improving performance, it maintains the inherent advantages of flexible Rogowski coils, such as portability and ease of installation. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the flexible Rogowski coil device of the present invention; Figure 2 This is a schematic diagram of the internal structure of the Rogowski coil device of the present invention; Figure 3This is an internal sectional view of the main coil of the present invention; Figure 4 This is a disassembly diagram of the connector module of the present invention; Figure 5 This is a partially enlarged schematic diagram of part A of the present invention; Figure 6 This is an internal sectional view of the I-shaped skeleton tube of the present invention; Figure 7 This is a flowchart of the compensation measurement method for the flexible Rogowski coil of the present invention.

[0024] In the diagram: 1. Main coil; 11. Flexible non-magnetic wire core; 12. Main winding; 13. Interface gap; 2. I-shaped skeleton tube; 21. Compensating winding; 22. First receiving cavity; 23. Second receiving cavity; 3. Housing; 4. Connector module; 41. Mechanical interface; 411. Engaging part; 412. Retaining compartment; 42. Connector base; 5. Circuit board. Detailed Implementation

[0025] The present application will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0026] Example 1: like Figure 1 , Figure 2 As shown, this embodiment provides a flexible Rogowski coil current sensor, including a housing 3, a main coil 1, a connector module 4, and a circuit board 5 assembled inside the housing 3; the housing 3 is preferably made of insulating material to provide mechanical support and electrical isolation; the circuit board 5 integrates a signal processing circuit, including an integration circuit and a signal processing unit, for processing the induced signal and outputting a voltage signal proportional to the measured current.

[0027] The main coil 1 includes a flexible non-magnetic wire core 11 and a main winding 12 wound around the flexible non-magnetic wire core 11; the fixed end of the main coil 1 is fixed inside the housing 3 and electrically connected to the circuit board 5, and its movable end is connected to the housing 3 in an open-close manner through the connector module 4. The connector module 4 includes a mechanical connector 41 disposed at the movable end of the main coil 1 and a connector base 42 disposed on one side of the housing 3. The mechanical connector 41 includes a locking part 411 and a receiving compartment 412, wherein the flexible non-magnetic wire core 11 and the end of the main winding 12 are fixed in the receiving compartment 412. The connector base 42 has a through-hole structure, and its inner diameter is slightly larger than the outer diameter of the mechanical connector 41, so that the mechanical connector 41 can be smoothly inserted into and locked in the connector base 42 to achieve rapid closing and opening. The locking part 411 may adopt a snap-fit ​​mechanism to ensure mechanical stability and electrical contact reliability during closing.

[0028] Preferably, the current sensor further includes an I-shaped frame cylinder 2 and a compensation winding 21 disposed within the housing 3. The I-shaped frame cylinder 2 is made of insulating material, is fitted inside the housing 3, and is sleeved around the interface gap 13 formed by the mating of the fixed end and the movable end of the main coil 1. The structural design of the I-shaped frame cylinder 2 allows for precise alignment of the fixed end and the movable end, reducing assembly errors. The compensation winding 21 is wound around the periphery of the I-shaped frame cylinder 2, with its winding direction consistent with that of the main winding 12, and its axial width is greater than the width of the interface gap 13 between the fixed end and the movable end of the main coil 1. The compensation winding 21 is connected in series with the main winding 12 to form a composite sensing unit, the output end of which is electrically connected to the circuit board 5.

[0029] like Figure 3 As shown, when the main coil 1 is closed, the magnetic flux path at the interface gap 13 is interrupted due to the winding discontinuity, resulting in a lower magnetic induction intensity in this region compared to the continuous portion of the coil. The compensation winding 21 generates an additional induced electromotive force (EMF) by coupling the residual magnetic flux in this region. This EMF is then superimposed in series with the EMF of the main winding 12, thereby compensating for the signal loss caused by the structural discontinuity at the signal level. The axial width of the compensation winding 21 is greater than the physical length of the interface gap 13 to ensure that it can fully cover the affected edge magnetic field regions on both sides of the gap, achieving more complete compensation. The number of turns of the compensation winding 21 can be optimized based on the length of the interface gap 13, the number of turns of the main winding 12, and the magnetic coupling characteristics, for example, by determining it through electromagnetic simulation or experimental calibration, to maximize the compensation effect.

[0030] The interface gaps shown in the attached drawings are for structural illustration only. For convenience, the actual structural gaps will be smaller than those shown in the drawings.

[0031] Preferably, in this embodiment, the circuit board 5 is provided with an integrating circuit and a signal processing unit. The output terminal of the composite induction unit is electrically connected to the input terminal of the integrating circuit, and the output terminal of the integrating circuit is electrically connected to the input terminal of the signal processing unit. The integrating circuit can be in the form of an RC passive integrating network or an active integrating amplifier, responsible for integrating the coil induced voltage into a standard signal output proportional to the primary current. The signal processing unit may include an amplifier, a filter, and an analog-to-digital converter for signal conditioning and output interface adaptation. The induced voltage of the Rogowski coil is proportional to the rate of change of the measured current. The integrating circuit can convert this voltage signal into a DC or low-frequency AC signal proportional to the amplitude of the measured current, facilitating subsequent reading by the measuring equipment.

[0032] Preferably, the I-shaped skeleton tube 2 includes a first receiving cavity 22 and a second receiving cavity 23. The fixed end of the main coil 1 extends into the first receiving cavity 22 and is fixed therein by adhesive. The I-shaped skeleton tube 2 ensures that when the main coil 1 is closed, its fixed end and movable end can be precisely aligned and enter the predetermined position inside the I-shaped skeleton tube 2, so that the interface gap 13 is accurately covered by the compensating winding 21. The second receiving cavity 23 provides a guiding and receiving space for the mechanical connector 41, improving the smoothness of opening and closing and the structural stability after closing, and avoiding additional measurement errors caused by connector shaking.

[0033] Preferably, the outer diameter of the receiving chamber 412 of the mechanical connector 41 is smaller than the outer diameter of the engaging portion 411 and the inner diameter of the second receiving cavity 23, so that the mechanical connector 41 can be smoothly inserted into the second receiving cavity 23, while ensuring mechanical stability and electrical continuity when closed. The interior of the receiving chamber 412 can be filled with potting material to fix the end of the main winding 12 and enhance insulation performance.

[0034] The flexible Rogowski coil current sensor of this invention effectively eliminates measurement errors at the flexible open Rogowski coil connector through the above structure. It has the advantages of simple structure, convenient installation, and high compensation accuracy, and is suitable for power systems, high-frequency current measurement, motor testing, and portable current probes.

[0035] Example 2: like Figure 6 As shown, this embodiment provides a measurement method based on a flexible Rogowski coil, the method comprising the following steps: S1: Determine the compensation parameters: The compensation parameters include the target number of turns of the compensation winding and the axial width of the coil; wherein, the target number of turns N is calculated by the formula N=k×n×L; where n is the number of turns per unit length of the main winding 12, L is the length of the blank area of ​​the connector, k is a correction coefficient between 0.8 and 1.2, and the axial width of the compensation winding 21 is configured to be greater than the axial length of the interface gap 13 between the fixed end and the movable end of the main coil 1 after it is engaged; Theoretically, when k=1, the total ampere-turns of the compensating winding 21 are exactly equal to the number of turns missing from the main winding 12 in a continuous segment of length L, theoretically achieving perfect compensation. However, in practical applications, the edge magnetic field effect causes the effective magnetic flux influence area at the interface gap 13 to be larger than its physical length L; simultaneously, factors such as differences in mutual inductance between windings, manufacturing tolerances, and material inconsistencies all affect the compensation effect. Therefore, setting the k value within the range of 0.8 to 1.2 provides adjustment space for practical optimization. Through subsequent fine-tuning under standard current, the optimal compensation point for a specific coil structure can be found, minimizing the measurement error at that position.

[0036] Meanwhile, the axial width of the compensation winding 21 is configured to be greater than the physical length L of the interface gap 13. This design ensures that the compensation winding 21 can fully cover the areas on both sides of the gap affected by the edge magnetic field, thereby capturing the edge magnetic flux and achieving more complete compensation, avoiding undercompensation due to insufficient compensation area.

[0037] S2: Arrange the compensation winding 21: Set an I-shaped skeleton tube 2 around the interface gap 13, and wind the compensation winding 21 around the I-shaped skeleton tube 2. The winding direction of the compensation winding 21 is configured so that the direction of its induced electromotive force is consistent with the direction of the electromotive force induced by the main winding 12 in the continuous part. S3: Electrical connection and signal integration: The compensation winding 21 and the main winding 12 are connected in series to form a composite induction unit; the output terminal of the composite induction unit is electrically connected to the input terminal of the integrating circuit, which is responsible for converting the differential signal output by the induction coil into a voltage signal proportional to the amplitude of the measured current.

[0038] S4: Self-calibration step, the main coil 1 is wrapped around the periphery of a conductor carrying a known standard current, and the movable end of the main coil 1 is connected to the housing 3; based on the difference between the output signal of the integrator circuit and the corresponding theoretical expected value, the final output of the composite sensing unit is calibrated by establishing a mathematical relationship model between the measured signal and the standard value.

[0039] Example 3: This embodiment further refines the self-calibration step in the aforementioned measurement method, specifically illustrating a high-precision digital calibration method for flexible Rogowski coils. This method establishes an accurate mathematical model between the output voltage and the standard current to effectively compensate for the sensor's system errors, thereby achieving high-precision measurement over a wide current range. The method described in this embodiment can be executed by a signal processing unit integrated on circuit board 5.

[0040] The establishment of a mathematical relationship model between the measurement signal and the standard value specifically includes the following steps: S41: Data Acquisition: In a controlled calibration environment, the flexible Rogowski coil is wound around the periphery of a conductor carrying a known standard current; m different known standard currents and their corresponding integrator circuit output voltages are acquired, forming a data point set {( , ),( , ),…,( , The range of collected current values ​​covers the expected range of the current to be measured in practical applications of the flexible Rogowski coil device. S42: Using a polynomial fitting algorithm, establish a calibration current value with the output voltage V as the independent variable. The interpolation polynomial function for the dependent variable: Where k is the order of the polynomial (0 < k ... <k≤m), , ... The coefficients are determined through fitting; Preferably, the value of k ranges from 2 to 5. A lower order may fail to adequately fit the nonlinearity of the system, while a higher order can easily introduce overfitting, leading to poor model performance at non-calibration points. The optimal order can be determined by observing the fitting residuals or using cross-validation.

[0041] S43: Real-time calibration: During subsequent measurements, the voltage value output by the integrating circuit in real time will be used for calibration. Substituting the given relationship, the calibrated current value is calculated and output in real time. ( ).

[0042] Example 4: This embodiment provides another specific implementation of a high-precision self-calibration method for flexible Rogowski coils. This method focuses on directly modeling the error characteristics of the sensor's output voltage and utilizes Lagrange interpolation combined with an iterative strategy to achieve successive approximation and effective compensation of system errors, ultimately achieving high-precision measurement. This method is particularly suitable for applications with extreme requirements for linearity and absolute accuracy.

[0043] In this embodiment, establishing the mathematical relationship model between the measurement signal and the standard value can also be achieved through the following steps: S41: Data Acquisition: Data acquisition is performed on a controlled and traceable calibration platform; based on the theoretical transfer function of the Rogowski coil and standard current. Calculate the corresponding theoretical expected voltage value. ; The voltage output of the integrator circuit of the flexible Rogowski coil device was measured and recorded using a data acquisition system. To reduce the impact of random noise, multiple samples are taken at each current point, and their average value is calculated as a stable value. ; Thus, m calibration data points are obtained, each data point containing a pair of voltage values; The number of calibration data points, m, is at least three to ensure that a meaningful interpolation model can be constructed. Preferably, m ranges from 5 to 15, and the voltage measurements of these data points... The voltage output range of the sensor should be covered as evenly as possible across the entire range that the sensor is expected to operate on in actual measurements, from a small signal close to zero to the maximum output voltage corresponding to the rated current.

[0044] S42: Difference Calculation: Calculate the voltage difference at each calibration point. ; S43: Interpolation Model Construction: Based on Lagrange interpolation, a model is constructed using induced voltage. As the independent variable, the voltage calibration value is used. The interpolation polynomial for the dependent variable: in, Let the expression be a Lagrange polynomial, and its expression be: S44: For the Rogowski coil induced voltage measured in real time Calculate its calibrated voltage value: .

[0045] S45: Iterative calibration: In order to further eliminate any possible residual system errors, especially in regions where nonlinearity is significant or the initial model accuracy has not yet reached its limit, this embodiment introduces an iterative calibration process; The voltage value obtained after the first calibration Consider it as a new set of measurements; with this new set of measurements value replaces the original Repeat steps S42 to S44; This iterative process can be repeated, denoted as the nth iteration. The iteration termination condition is set as follows: when the maximum absolute difference between the final calibration results obtained from two consecutive iterations is less than a preset threshold ε, i.e. <ε. Through several iterations, the systematic residual error can be quickly converged to a negligible level.

[0046] This method is particularly suitable for calibration laboratories, high-precision metrology equipment, and scenarios where the accuracy of existing sensors is being upgraded, laying a technical foundation for ensuring that flexible Rogowski coils provide reliable and accurate data in harsh measurement environments.

[0047] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0048] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0049] It is understood that those skilled in the art can make equivalent substitutions or changes based on the technical solution and design concept of this application, and all such changes or substitutions should fall within the protection scope of this application.

Claims

1. A flexible Rogowski coil current sensor, comprising a housing (3), a main coil (1), a connector module (4), and a circuit board (5) assembled within the housing (3); the main coil (1) comprises a flexible non-magnetic core (11) and a main winding resistor wound around the flexible non-magnetic core (11); the fixed end of the main coil (1) is fixed within the housing (3) and electrically connected to the circuit board (5), and its movable end is connected to the housing (3) in an open-close manner via the connector module (4); the connector module (4) comprises a mechanical connector (41) disposed at the movable end of the main coil (1) and a connector base (42) disposed on one side of the housing (3); characterized in that: The current sensor also includes an I-shaped skeleton cylinder (2) and a compensation winding (21) disposed inside the housing (3); the I-shaped skeleton cylinder (2) is engaged inside the housing (3) and sleeved around the interface gap (13) formed by the docking of the fixed end and the movable end of the main coil (1); the compensation winding (21) is wound around the periphery of the I-shaped skeleton cylinder (2), and its axial width is greater than the width of the interface gap (13) between the fixed end and the movable end of the main coil (1); the connector base (42) is a through hole structure, and its inner diameter is greater than the outer diameter of the mechanical connector (41); The compensation winding (21) is connected in series with the main winding (12) to form a composite induction unit. The output end of the composite induction unit is electrically connected to the circuit board (5).

2. The flexible Rogowski coil current sensor according to claim 1, characterized in that, The circuit board (5) is provided with an integrating circuit and a signal processing unit. The output terminal of the composite sensing unit is electrically connected to the input terminal of the integrating circuit, and the output terminal of the integrating circuit is electrically connected to the input terminal of the signal processing unit.

3. A flexible Rogowski coil current sensor according to claim 1, characterized in that, The I-shaped skeleton tube (2) includes a first receiving cavity (22) and a second receiving cavity (23). The fixed end of the main coil (1) extends into the first receiving cavity (22) and is fixed therein.

4. A flexible Rogowski coil current sensor according to claim 3, characterized in that, The mechanical connector (41) includes a locking part (411) and a receiving chamber (412) that engage with the connector base (42). The receiving chamber contains the flexible non-magnetic wire core (11) and the end of the main winding (12). The outer diameter of the receiving chamber (412) is smaller than the outer diameter of the locking part (411) and the inner diameter of the second receiving cavity (23). The mechanical connector (41) is movably connected to the connector base (42) and can be embedded in the second receiving cavity (23).

5. A measurement method based on a flexible Rogowski coil, characterized in that, The method includes the following steps: S1: Determine the compensation parameters: The compensation parameters include the target number of turns of the compensation winding and the axial width of the coil; wherein, the target number of turns N is calculated by the formula N=k×n×L; where n is the number of turns per unit length of the main winding (12), L is the length of the blank area of ​​the connector, k is a correction coefficient between 0.8 and 1.2, and the axial width of the compensation winding (21) is configured to be greater than the axial length of the interface gap (13) between the fixed end and the movable end of the main coil (1) after it is engaged; S2: Arrange the compensation winding (21): Set an I-shaped skeleton tube (2) around the interface gap (13), and wind the compensation winding (21) around the I-shaped skeleton tube (2). The winding direction of the compensation winding (21) is configured so that the direction of its induced electromotive force is consistent with the direction of the electromotive force induced by the main winding (12) in the continuous part. S3: Electrical connection and signal integration: The compensation winding (21) and the main winding (12) are connected in series to form a composite induction unit, and the output of the composite induction unit is connected to the integration circuit. S4: Self-calibration step, the main coil (1) is wrapped around the periphery of a conductor carrying a known standard current, and the movable end of the main coil (1) is connected to the housing (3); based on the difference between the output signal of the integrator circuit and the corresponding theoretical expected value, the final output of the composite induction unit is calibrated by establishing a mathematical relationship model between the measured signal and the standard value.

6. The dynamic compensation measurement method according to claim 5, characterized in that, Step S4, which establishes a mathematical relationship model between the measurement signal and the standard value, includes the following steps: S41: Data Acquisition: Obtain m different known standard currents and their corresponding integrator circuit output voltages to form a data point set {( , ),( , ),…,( , )}; S42: Using a polynomial fitting algorithm, establish a calibration current value with the output voltage V as the independent variable. The interpolation polynomial function for the dependent variable: ; Where k is the order of the polynomial (0 < k ... <k≤m), , ... The coefficients are determined through fitting; S43: Real-time calibration: During subsequent measurements, the voltage value output by the integrating circuit in real time will be used for calibration. Substituting the given relationship, the calibrated current value is calculated and output in real time. ( ).

7. The measurement method according to claim 6, characterized in that, The range of values ​​for the m different known standard currents covers the expected range of the current to be measured in the practical application of the flexible Rogowski coil device.

8. The measurement method according to claim 5, characterized in that, The establishment of the mathematical relationship model between the measurement signal and the standard value in step S4 can also be achieved through the following steps: S41: Data Acquisition: Acquire m calibration data points, each data point including the measured value of the Rogowski coil induced voltage. and the corresponding theoretical voltage value where i = 1, 2, ..., m; S42： Difference Calculation: Calculate the voltage difference at each calibration point: ; S43: Interpolation Model Construction: Based on Lagrange interpolation, a model is constructed using induced voltage. As the independent variable, the voltage calibration value is used. The interpolation polynomial for the dependent variable: in, Let the expression be a Lagrange polynomial, and its expression be: S44: For the Rogowski coil induced voltage measured in real time Calculate its calibrated voltage value: .

9. The measurement method according to claim 8, characterized in that, The theoretical voltage value The theoretical transfer function of the standard current source and Rogowski coil is calculated; the number of calibration data points m is at least 3, and the voltage measurement value of the calibration data points is... It covers the expected voltage range in actual measurements.

10. The measurement method according to claim 8, characterized in that, The method further includes an iterative calibration step: taking the voltage value after the first calibration... As a new measurement value, the difference calculation and interpolation model construction process in claim 8 is repeated, and multiple iterative calibrations are performed until the difference between at least two consecutive calibration results is less than a preset threshold.

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