Unified characterization method and device for sensitivity of non-intrusive current detection scene and sensor

Abstract

The invention discloses a non-intrusive current detection scene sensitivity unified characterization method and device and a sensor, and belongs to the technical field of electric power measurement. The method comprises the following steps: taking a measured current in a conductor as a research object, and establishing a density distribution model of the measured current in the conductor; calculating three-dimensional space magnetic field distribution outside the conductor according to the current density distribution model; in combination with a three-dimensional space structure model of the sensor, performing sensor main axis direction projection on three-dimensional space magnetic field distribution to obtain effective magnetic induction intensity, and calculating to obtain effective magnetic flux; differentiating the effective magnetic flux to obtain coil induced voltage; and integrating the induced voltage of the coil through a signal reduction circuit to obtain an output voltage proportional to the effective magnetic flux, and obtaining a sensitivity function of the non-intrusive current sensor. The sensitivity unified characterization method is suitable for any measuring device structure and coil structure; and the sensitivity of any position in different application scenes can be represented in a unified manner.

Description

Technical Field

[0001] This invention belongs to the field of power measurement technology, and more specifically, relates to a unified sensitivity characterization method, device and sensor for non-invasive current detection scenarios. Background Technology

[0002] Non-invasive current sensors indirectly measure current by sensing the magnetic field generated by a current-carrying conductor in space. They offer advantages such as not requiring disruption of the existing electrical structure and suitability for complex current-carrying environments. However, they differ from invasive current sensors (such as Rogowski coils) in their method of sensing the magnetic field. In invasive current sensors, the Rogowski coil surrounds the conductor being measured, allowing for circumferential path integration of the magnetic field generated by the current. According to Ampere's circuital law, this integration result is determined solely by the measured current and is independent of the specific distribution of the magnetic field in space. Therefore, its sensitivity is determined only by the number of coil turns and its geometry, and is independent of the installation location and orientation.

[0003] Non-invasive current sensors do not surround the current-carrying conductor; they can only sense the magnetic field generated by the current in a local area of ​​space. This makes the sensitivity no longer an inherent parameter determined by the device structure, but a system response quantity determined by both the magnetic field distribution and the spatial position. It is difficult to accurately determine and uniformly characterize, thus increasing the difficulty of quantitative current measurement.

[0004] In existing research on the sensitivity of non-invasive current sensors, some studies have attempted to analyze the sensitivity from the perspective of magnetic field modeling or experimental calibration. For example, some studies are based on a simple central model and establish the relationship between the sensor output and the magnetic field; others obtain an empirical proportionality coefficient between the sensor output and the current through experimental calibration under fixed installation conditions for subsequent current measurement. However, these methods usually rely on specific structural assumptions or fixed operating conditions, and their sensitivity descriptions are difficult to reflect the systematic influence of changes in spatial position, orientation, and frequency on the sensor response. When the current-carrying conductor structure, installation conditions, or operating frequency changes, the sensitivity changes accordingly, requiring recharacterization or recalibration, which brings considerable inconvenience to engineering applications and system deployment.

[0005] Therefore, based on existing research, there is an urgent need for a method that includes spatial characteristics, frequency characteristics, and sensor sensitivity characterization to achieve a unified characterization of the sensitivity of non-invasive current sensors under different fluid-carrying structures, installation conditions, and operating frequencies, thereby ensuring accurate monitoring of current signals. Summary of the Invention

[0006] To address the shortcomings of related technologies, the present invention aims to provide a unified sensitivity characterization method, device, and sensor for non-invasive current detection scenarios. This invention seeks to solve the problem of low current signal monitoring accuracy caused by the inability to unify the sensitivity characterization of non-invasive current sensors under different fluid-carrying structures, installation conditions, and operating frequencies.

[0007] To achieve the above objectives, this invention provides a unified sensitivity characterization method for non-invasive current detection scenarios, comprising: Taking the measured current in the conductor as the research object, the current direction of the measured current as the z-axis, and the plane where the cross-section of the conductor is located as the xy plane, a three-dimensional coordinate system is established to establish a model of the measured current density distribution inside the conductor. The three-dimensional spatial magnetic field distribution outside the conductor is calculated based on the current density distribution model. By combining the three-dimensional spatial structure model of the non-invasive current sensor, the three-dimensional spatial magnetic field distribution is projected along the sensor's principal axis to obtain the effective magnetic induction intensity; the effective magnetic induction intensity is then integrated on the effective cross-section of the magnetic core to obtain the effective magnetic flux. The effective magnetic flux is differentiated to calculate the coil induced voltage in the non-invasive current sensor; The coil-induced voltage is integrated by a signal restoration circuit to obtain an output voltage proportional to the effective magnetic flux, thereby obtaining the sensitivity function of the non-invasive current sensor. The sensitivity function is expressed as:

[0008] in, f The operating frequency of the current being measured in the conductor; This describes the distribution of the measured current in the conductor. r ′ is the position vector of any point within the conductor's cross-section; r This is the position vector of the magnetic core of the non-invasive current sensor in space. is the unit vector along the principal axis of the magnetic core; μ eff The effective permeability of the magnetic core; A core This represents the effective cross-sectional area of ​​the magnetic core. K It is the proportional coefficient of the signal restoration circuit; N This represents the number of turns in the coil.

[0009] Optionally, the step of establishing a model of the measured current density distribution inside the conductor, taking the measured current in the conductor as the research object, includes: At frequency f Under operating conditions, the measured current density inside the conductor Due to the skin effect, the electromagnetic diffusion equation is satisfied:

[0010] in, ω =2π f Angular frequency, μ Permeability of the conductor σ The conductivity of a conductor; Based on the constraint that the measured current density distribution inside the conductor is consistent with the measured current in the conductor, the current density is normalized to obtain the measured current from the conductor. i Current density distribution inside the conductor being measured The mapping relationship; The constraints are as follows:

[0011] in, dS source Let be the area of ​​a small element of the conductor's cross-section. S source The cross-sectional area of ​​the conductor to be measured current; The solution yields the measured current density distribution function inside the conductor as a function of frequency. .

[0012] Optionally, calculating the three-dimensional spatial magnetic field distribution outside the conductor based on the current density distribution model includes: Based on the Biot-Savart law, the measured current of the conductor is established according to the current density distribution model. i The distribution of the three-dimensional magnetic field at any point in space:

[0013] in, The measured current density within the conductor. For frequency f Lower spatial position r Magnetic flux density at the location; V This indicates the volume area occupied by the sensor.

[0014] Optionally, the three-dimensional spatial structure model of the non-invasive current sensor is used to project the three-dimensional spatial magnetic field distribution along the sensor's principal axis to obtain the effective magnetic flux density; the effective magnetic flux density is then integrated over the effective cross-section of the magnetic core to obtain the effective magnetic flux, including: Based on the magnetic core position parameters of the non-invasive current sensor r c Attitude parameters Magnetic core permeability characteristics μ r、 Effective permeability μ eff and effective cross-sectional area A core Parameters were used to establish a three-dimensional spatial structure model of the non-invasive current sensor; Let the direction of the sensor core spindle be... The three-dimensional spatial magnetic field distribution is projected onto the main axis of the magnetic core:

[0015] Among them, the direction of the main axis of the sensor core is the attitude parameter; Permeability obtained from the core material datasheet Real permeability Imaginary permeability , And through geometric demagnetization factor N d Effective permeability is obtained:

[0016] in, N d It is related to the shape and size of the magnetic core; Based on the complex permeability of the magnetic core and the cross-sectional area of ​​the magnetic core A core The effective magnetic flux is obtained by integrating the effective magnetic induction intensity over the effective cross-section of the magnetic core.

[0017] Optionally, the expression for the coil induced voltage is: .

[0018] Optionally, the expression for the output voltage is: ; in, K It is the proportional coefficient of the transfer function in the signal restoration circuit, which is determined by the resistors, capacitors, and operational amplifier parameters in the signal restoration circuit.

[0019] Optionally, when the conductor is a long, straight, circular wire, the amplitude of the spatial magnetic field is only related to the magnitude of the measured current in the conductor and the geometric distance between the non-invasive current sensor and the conductor. The sensitivity function is expressed as:

[0020] Among them, the cross-section of the long straight circular conductor has a radius of... R A circle, the length of which is along z Extending along the axial direction; μ 0 represents the permeability of air. ρ This is the radial distance from the observation point to the axis of the circular conductor.

[0021] Secondly, the present invention also provides a unified sensitivity characterization method for non-invasive current detection scenarios, comprising: The current density calculation module is used to establish a three-dimensional coordinate system with the measured current in the conductor as the research object, the current direction of the measured current as the z-axis, and the plane where the cross-section of the conductor is located as the xy plane, thereby establishing a model of the measured current density distribution inside the conductor. The spatial magnetic field distribution calculation module is used to calculate the three-dimensional spatial magnetic field distribution outside the conductor based on the current density distribution model. The effective magnetic flux calculation module is used to combine the three-dimensional spatial structure model of the non-invasive current sensor, project the three-dimensional spatial magnetic field distribution along the sensor's principal axis to obtain the effective magnetic induction intensity; and integrate the effective magnetic induction intensity on the effective cross section of the magnetic core to obtain the effective magnetic flux. The sensing voltage module is used to differentiate the effective magnetic flux and calculate the coil sensing voltage in the non-invasive current sensor. The sensitivity function construction module is used to integrate the coil induced voltage through the signal restoration circuit to obtain an output voltage proportional to the effective magnetic flux, thereby obtaining the sensitivity function of the non-invasive current sensor. The sensitivity function is expressed as:

[0022] in, f The operating frequency of the current being measured in the conductor; This describes the distribution of the measured current in the conductor. r ′ is the position vector of any point within the conductor's cross-section; r This is the position vector of the magnetic core of the non-invasive current sensor in space. is the unit vector along the principal axis of the magnetic core; μ eff The effective permeability of the magnetic core; A core This represents the effective cross-sectional area of ​​the magnetic core. K It is the proportional coefficient of the signal restoration circuit; N This represents the number of turns in the coil.

[0023] Thirdly, the present invention also provides a non-invasive current sensor, wherein the sensitivity of the non-invasive current sensor in a non-invasive current detection scenario is represented by a unified sensitivity characterization method for non-invasive current detection scenarios as described in any one of the first aspects.

[0024] Compared with the prior art, the above-described technical solutions conceived in this invention can achieve the following beneficial effects: 1. This invention provides a unified sensitivity characterization method for non-invasive current detection scenarios. By explicitly incorporating factors such as three-dimensional magnetic field distribution, core attitude, core spatial position, core cross-sectional shape, and frequency into the sensitivity function, the sensitivity of the sensor at any position and angle can be calculated. This avoids the limitations of relying on specific structures or empirical calibration, providing a unified characterization standard for sensitivity analysis in different application scenarios. The constructed sensitivity function of the non-invasive current sensor is not limited to the conductor being a line current or a specific geometric structure, and is applicable to complex current-carrying and non-uniform magnetic field environments such as converters, power electronic devices, and busbar monitoring. It possesses good structure independence and a wide range of applicability.

[0025] 2. This invention provides a unified sensitivity characterization method for non-invasive current detection scenarios, taking into account the conductor skin effect, electromagnetic diffusion behavior and magnetic core frequency characteristics, so that the sensitivity can be accurately calculated in the range from power frequency to high frequency; it significantly improves the accuracy of frequency response and realizes wideband current sensing.

[0026] 3. This invention provides a unified sensitivity characterization method for non-invasive current detection scenarios. Based on the constructed sensitivity function of the non-invasive current sensor, this solution combines model prediction with a small number of measurement points to quickly complete sensitivity calibration without repeated experimental calibration, predict the sensor response characteristics under different installation conditions, improve the efficiency and reliability of the sensor in field deployment, and achieve rapid calibration and engineering deployment. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the rectangular conductor busbar and sensor in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the current density distribution at different frequencies of the rectangular conductor busbar in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the spatial distribution of the magnetic field around the rectangular conductor busbar in Embodiment 1 of the present invention; Figure 4 The ratio coefficient of the magnetic field strength of the sensor to the measured current in Embodiment 1 of the present invention. B / i Schematic diagram of the curve of frequency variation; Figure 5 This refers to the three-dimensional model of the magnetic core and the projection model of the effective component of the normal direction of magnetic induction intensity in Embodiment 1 of the present invention. Figure 6 This is a schematic diagram of the non-uniform magnetic field distribution across the cross-section of the sensor core in Embodiment 1 of the present invention; Figure 7The ratio coefficient of magnetic flux to measured current in Embodiment 1 of the present invention. Φ / i Schematic diagram of the curve of frequency variation; Figure 8 This is a schematic diagram of a specific circuit of the signal restoration circuit in Embodiment 1 of the present invention; Figure 9 The sensitivity frequency response curve is shown in Embodiment 1 of the present invention. Figure 10 This is a schematic diagram of the spatial distribution of the magnetic field around a long, straight, circular conductor in Embodiment 2 of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0029] Example 1 Because non-invasive current sensors do not surround the current-carrying conductor, they can only sense the magnetic field generated by the current in a local area of ​​space. Therefore, sensitivity is no longer an inherent parameter determined by the device structure, but rather a system response quantity determined by both the magnetic field distribution and spatial location. This makes it difficult to accurately determine and uniformly characterize, thus increasing the difficulty of quantitative current measurement, mainly in the following aspects: 1) The sensitivity of non-invasive current sensors is highly dependent on the space installation conditions.

[0030] Under non-invasive measurement conditions, the sensor does not surround a current-carrying conductor, and its output originates from a local spatial magnetic field. Due to the position-dependent and directional nature of the spatial magnetic field, the sensor sensitivity is not only related to the current magnitude but is also significantly affected by the installation location, orientation, and core structure characteristics, exhibiting a significant spatial dependence.

[0031] 2) Sensitivity is affected by the spatial distribution of the magnetic field generated by the measured current itself, making it difficult to characterize uniformly.

[0032] In practical applications, the structure of the current-carrying conductors varies, and their internal current density exhibits significant non-uniformity under medium- and high-frequency operating conditions due to the skin effect. Current density directly determines the amplitude, direction, and spatial distribution characteristics of the external magnetic field. Since the output of non-invasive current sensors depends on the spatial magnetic field distribution, this sensitivity is affected by the distribution of the spatial magnetic field generated by the measured current, making it difficult to characterize using a single parameter and further increasing the complexity of sensitivity modeling.

[0033] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a sensitivity characterization method for a non-invasive current sensor. This method constructs a mathematical relationship between the measured current and the sensor's output voltage through the following steps: Using the measured current in a conductor as the sensing object, a model of the measured current density distribution inside the conductor is established; based on the current density distribution, the three-dimensional spatial magnetic field distribution outside the conductor is further calculated; combining the spatial position, orientation, and material permeability characteristics of the magnetic core in the non-invasive current sensor, the magnetic field is directionally projected; the magnetic flux density is integrated over the effective cross-section of the magnetic core to obtain the effective magnetic flux; the coil induced voltage is calculated based on the electromagnetic induction relationship; the coil induced voltage is then calculated again based on the electromagnetic induction principle, and the coil voltage is integrated through a signal restoration circuit to obtain an output voltage proportional to the magnetic flux; thus, a complete transmission relationship from the measured current to the output voltage is constructed, ultimately obtaining the sensitivity function of the non-invasive current sensor. Based on the sensitivity model, rapid sensor calibration and current sensing are achieved.

[0034] Through the above implementation process, the sensor output response can be predicted based solely on the sensor's geometric parameters, material parameters, and installation orientation, without the need to switch the conductor on or off or rely on empirical calibration. This allows for the acquisition of the sensitivity function of a non-invasive current sensor, enabling rapid sensor calibration, current reconstruction, and rapid deployment in engineering applications.

[0035] The sensitivity of a non-invasive current sensor is defined as the ratio between the sensor's output voltage and the measured current.

[0036] This invention provides a unified sensitivity characterization method for non-invasive current detection scenarios, comprising: Taking the measured current in the conductor as the research object, the current direction of the measured current as the z-axis, and the plane where the cross-section of the conductor is located as the xy plane, a three-dimensional coordinate system is established to establish a model of the measured current density distribution inside the conductor. The three-dimensional spatial magnetic field distribution outside the conductor under test is calculated based on the current density distribution model. By combining the three-dimensional spatial structure model of the non-invasive current sensor, the three-dimensional spatial magnetic field distribution is projected along the sensor's principal axis to obtain the effective magnetic induction intensity; the effective magnetic induction intensity is then integrated on the effective cross-section of the magnetic core to obtain the effective magnetic flux. The effective magnetic flux is differentiated to calculate the coil induced voltage in the non-invasive current sensor; The coil-induced voltage is integrated by a signal restoration circuit to obtain an output voltage proportional to the effective magnetic flux, thereby obtaining the sensitivity function of the non-invasive current sensor. The sensitivity function constructed in this invention can be expressed by the following formula: (1) in, f The operating frequency of the current being measured; This describes the distribution of the measured current in the conductor. r ′ is the position vector of any point within the conductor's cross-section; r Let be the position vector of the sensor core in space; is the unit vector along the principal axis of the magnetic core; μ eff The effective permeability of the magnetic core is used to characterize the combined effect of the demagnetization effect introduced by the core material properties and the core geometry on the magnetic field concentration capability. A core This represents the effective cross-sectional area of ​​the magnetic core. K It is the proportional coefficient of the signal restoration circuit, which is determined by the sensor parameters and the parameters of the resistor, capacitor and operational amplifier in the signal restoration circuit. N This represents the number of turns in the coil.

[0037] Optionally, the step of establishing a model for the distribution of the measured current density inside the conductor, taking the measured current in the conductor as the research object, includes: At frequency f Under operating conditions, the measured current density inside the conductor Due to the skin effect, the electromagnetic diffusion equation is satisfied: (2) in, ω =2π f Angular frequency, μ Permeability of the conductor σ The conductivity of a conductor; Based on the constraint that the measured current density distribution inside the conductor is consistent with the measured current in the conductor, the current density is normalized to obtain the measured current from the conductor. i Current density distribution inside the conductor being measured The mapping relationship; The constraints are as follows: (3) in, dS source Let be the area of ​​a small element of the conductor's cross-section. S source The cross-sectional area of ​​the conductor to be measured current; The solution yields the measured current density distribution function inside the conductor as a function of frequency. .

[0038] Optionally, calculating the three-dimensional spatial magnetic field distribution outside the conductor based on the current density distribution model includes: Based on the Biot-Savart law, the measured current of the conductor is established according to the current density distribution model. i The distribution of the three-dimensional magnetic field at any point in space: (4) in, The measured current density within the conductor. For frequency f Lower spatial position r Magnetic flux density at the location; V This indicates the volume area occupied by the sensor.

[0039] The sensor installation location can be obtained through this model. r The magnetic field at that location changes with frequency.

[0040] Optionally, the three-dimensional spatial structure model of the non-invasive current sensor is used to project the three-dimensional spatial magnetic field distribution along the sensor's principal axis to obtain the effective magnetic flux density; the effective magnetic flux density is then integrated over the effective cross-section of the magnetic core to obtain the effective magnetic flux, including: Based on the magnetic core position parameters of the non-invasive current sensor r c Attitude parameters Magnetic core permeability characteristics μ r、 Effective permeability μ eff and effective cross-sectional area A core Parameters were used to establish a three-dimensional spatial structure model of the non-invasive current sensor; Let the direction of the sensor core spindle be... The three-dimensional spatial magnetic field distribution is projected onto the main axis of the magnetic core: (5) Among them, the direction of the main axis of the sensor core is the attitude parameter; Permeability obtained from the core material datasheet Real permeability Imaginary permeability , And through geometric demagnetization factor N d Effective permeability is obtained: (6) in, N d It is related to the shape and size of the magnetic core; Based on the complex permeability of the magnetic core and the cross-sectional area of ​​the magnetic core A coreThe effective magnetic flux is obtained by integrating the effective magnetic induction intensity over the effective cross-section of the magnetic core. (7) The core orientation angle, effective cross-sectional area, core permeability, and core position can all affect the effective magnetic flux of the sensor.

[0041] Optionally, the expression for the coil induced voltage is: (8) Optionally, the expression for the output voltage is: (9) in, K It is the proportional coefficient of the transfer function in the signal restoration circuit, which is determined by the resistors, capacitors, and operational amplifier parameters in the signal restoration circuit.

[0042] The sensitivity S The overall expression is as follows: (10) In this invention, sensitivity S It is not a simple empirical proportionality coefficient, but is determined by the spatial distribution of the measured current, the characteristics of the magnetic field distribution, the sensor parameters, and the installation conditions. Formula (1) serves as a unified representation of the sensitivity of non-invasive current sensors, explicitly expressing the relationship between the sensor output and the measured current as a function of multiple physical factors, thereby achieving a unified description of the sensor response characteristics under different application scenarios.

[0043] Furthermore, the sensitivity characterization method is independent of the specific conductor geometry or the form of the measured current model. The spatial measured current can originate from rectangular busbars, circular wires, multi-conductor parallel structures, or current-carrying conductors of arbitrary cross-sectional shapes; the corresponding spatial magnetic field distribution can be established based on the specific conductor structure, and the influence of different conductors and their current distributions on the sensitivity is determined by... The uniformity is reflected in formula (1).

[0044] Therefore, the sensitivity function given by formula (1) has universality and scalability, and can serve as a unified theoretical basis for sensitivity analysis, comparison, and calibration of non-invasive current sensors under different conductor structures, installation positions and orientations, and frequency conditions. The unified sensitivity characterization method provided by this invention is applicable to any measuring device structure and coil structure.

[0045] The following description, in conjunction with a preferred embodiment, illustrates the content involved in the above embodiments.

[0046] This embodiment uses a rectangular busbar as the conductor for the measured current and a coil wound around a cuboid magnetic core as the non-invasive current sensor structure. The detailed description of the measured current... i To output voltage v o The complete modeling process.

[0047] This embodiment provides a method for measuring the current under test. i Current density measured inside the rectangular busbar conductor J Then to the space magnetic field B Effective magnetic flux within the magnetic core Φ induced voltage of coil u and the output voltage after signal processing v o The complete modeling process.

[0048] In this embodiment of the invention, the sensitivity of the non-invasive current sensor is defined as the proportional relationship between the sensor output voltage and the measured current, and its overall functional form can be expressed as: (11) like Figure 1 As shown, this embodiment provides a three-dimensional sensitivity model for describing the magnetic field generated in space by a rectangular busbar conductor, with a cuboid sensor core. The conductor is a rectangular busbar, its cross-section lying in the xy plane, with cross-sectional dimensions of 2a × 2b, and the conductor length extending along the z-axis. The measured current... i along z Flow in the axial direction.

[0049] Under low-frequency operating conditions, the current density inside a rectangular busbar can be approximated as uniformly distributed within the cross-section. However, under medium- and high-frequency operating conditions, due to the skin effect, the current density will be significantly concentrated in the conductor edge region, resulting in a distinct spatial non-uniform distribution of the current density within the cross-section, such as... Figure 2 As shown. Therefore, it is necessary to solve the problem based on the electromagnetic diffusion equation. At a frequency of... f Under operating conditions, the measured current density inside the conductor Due to the skin effect, the distribution is no longer uniform, but instead satisfies the electromagnetic diffusion equation: (12) in, ω =2π f Angular frequency, μ Permeability of the conductor σ is the conductor's conductivity.

[0050] By solving (11), the current density distribution function varying with frequency can be obtained. To ensure that the calculated current density distribution is consistent with the measured current, the current density needs to be normalized to satisfy the following constraints: (13) in, dS Let the cross-sectional area of ​​the conductor be a small element. S This refers to the cross-sectional area of ​​a rectangular busbar. Through the above steps, the measured current is obtained... i Current density distribution inside the conductor being measured The mapping relationship provides a current basis for subsequent magnetic field modeling.

[0051] In this embodiment, the solution for the measured current density distribution inside the conductor can be achieved by numerical calculation.

[0052] Specifically, the rectangular busbar cross-sectional area can be discretized into several micro-element units, and the current density value of each micro-element unit can be solved separately. The normalization constraint condition ensures that the current after integration over the entire cross-sectional area is equal to the measured current. i .

[0053] Using the above method, the distribution of measured current density inside the conductor that varies with frequency can be obtained in a computer, which can be used for subsequent calculation of the space magnetic field.

[0054] like Figure 3 As shown, the current density distribution inside the rectangular busbar will generate a magnetic field in the space outside the conductor. Since the length of the busbar is much larger than its cross-sectional dimension, it can be regarded as a magnetic field along... z A long, straight conductor that extends uniformly along the axial direction has a relatively small sensor size along the conductor's axial direction, and the change in the axial magnetic field can be ignored, thus simplifying the three-dimensional problem into a two-dimensional volume current model.

[0055] Specifically, in this embodiment of the invention, at any spatial point outside the conductor magnetic field at the location This can be derived from the Biot-Savart law. At the observation point... The magnetic field at that location can be written as: (14) Specifically, in this embodiment of the invention, if the conductor is a long straight conductor, the above formula can be further simplified to a two-dimensional integral over the cross-sectional area of ​​the conductor, that is: (15) in, The location of the measured current point within the conductor's cross-section. Let be the position vector of the observation point relative to the point of the measured current. The distance between the two, μ 0 represents the permeability of air.

[0056] By integrating over the conductor cross-section region, the magnetic field vector at the observation point can be obtained. B ( r , f This allows us to obtain its amplitude and phase. For a specific location, we can obtain | B | / i The frequency response curve, such as Figure 4 As shown.

[0057] In this embodiment, the spatial magnetic field can be calculated using numerical integration.

[0058] Specifically, the magnetic field contribution generated at the sensor observation point is calculated for each current density element within the rectangular busbar cross-section, and the magnetic field vector at the observation point is obtained by integrating over the entire cross-sectional area.

[0059] Since the length of the busbar is much larger than its cross-sectional dimensions, the above calculations can be performed in a two-dimensional model, thereby reducing computational complexity and improving modeling efficiency.

[0060] like Figure 1 As shown, the magnetic core of the non-invasive current sensor is placed outside the rectangular busbar, and its center position is denoted as... r c The position of any point on the effective cross section inside the magnetic core is r The unit vector along the principal axis of the magnetic core is denoted as The angle between the direction of the magnetic core's principal axis and the direction of the magnetic field at its location is . θ .

[0061] At any point r Place, such as Figure 5 As shown, the core attitude is expressed by a unit vector along the core principal axis. This indicates that the projection component of the spatial magnetic field along the principal axis of the magnetic core is: (16) Considering the magnetization effect of the core material, factors related to the core shape and relative permeability are introduced. μ r Relevant effective permeability μ eff ( f ): (17) The equivalent magnetic flux density inside the magnetic core is: (18) Let the cross-sectional area of ​​the magnetic core be... A core The magnetic field distribution across the core cross section is as follows Figure 6 As shown, the effective magnetic flux through the cross-section of the magnetic core can be expressed as: (19) The position and attitude parameters can be determined by the sensor mounting structure dimensions or the geometric relationship of the fixed bracket.

[0062] Frequency-dependent permeability of magnetic core material This information can be obtained through material data sheets or experimental testing, and used as a frequency parameter in the magnetic flux calculation process to obtain the value of || at a fixed sensor position. Φ | / i The frequency response curve, such as Figure 7 As shown.

[0063] An induction coil is wound around the outside of a magnetic core. When the magnetic flux in the core changes with time, an induced voltage is generated in the coil. According to Faraday's law of electromagnetic induction, the induced voltage in the coil... It can be represented as: From magnetic flux Φ Calculate the induced voltage of the coil u : (20) in, N The number of turns in the coil is given. The induced voltage in the coil has a differential relationship with the magnetic flux, and its amplitude is proportional to the frequency.

[0064] In this embodiment, a signal restoration circuit is provided at the coil output terminal, such as... Figure 8 As shown, the signal restoration circuit is used to restore the amplitude and phase of the measured current based on the AC induced voltage generated by the signal acquisition coil. Specifically, the AC induced voltage generated by the signal acquisition coil has a differential relationship with the measured current, and the signal restoration circuit obtains the output voltage by integrating the coil induced voltage. v o The voltage v o It can reflect the amplitude and phase of the measured current.

[0065] The integrator circuit is used to restore the differential coil voltage to an output voltage proportional to the magnetic flux. The output voltage is then: (twenty one) in, K It is the proportional coefficient of the transfer function in the signal restoration circuit, which is determined by the resistance, capacitance and operational amplifier parameters in the signal restoration circuit.

[0066] This embodiment starts from the measured current. i To output voltage v oA complete model is created, defining the sensitivity of a non-invasive current sensor as the ratio of output voltage to measured current. This allows for the acquisition of the sensor's sensitivity function under different positions, orientations, and frequencies. The frequency response curve of the sensor's sensitivity at a fixed position is shown in the figure. Figure 9 As shown.

[0067] In this embodiment of the invention, based on the above-described current being measured... i To output voltage v o The complete modeling process allows the sensitivity of a non-invasive current sensor to be expressed as a function of multiple physical parameters. Specifically, the current density distribution function... Spatial magnetic field distribution Core attitude parameters ( , Frequency-dependent permeability of the core material μ eff ( f The parameters of the coil and the signal restoration circuit are uniformly incorporated into the sensitivity model, and the sensitivity function can be expressed as: (twenty two) Wherein, the sensitivity function S The output response characteristics of a non-invasive current sensor under given frequency, installation position, and attitude conditions are expressed as the sensitivity with respect to current density distribution, electromagnetic field spatial distribution, core attitude, and material parameters, thus constructing a multi-parameter coupled sensitivity model for the non-invasive current sensor.

[0068] This model allows for the prediction of sensor sensitivity values ​​without the need for actual power-on calibration, simply by inputting busbar dimensions, material parameters, core geometry parameters, and installation orientation information.

[0069] In embodiments of the present invention, such as Figure 8 As shown, the signal restoration circuit includes resistors. R amp1 ~ R amp4 ,capacitance C 1. C 2. First operational amplifier and second operational amplifier; R amp1 , R amp2 Together with the first operational amplifier, they form an inverting amplifier circuit. The output terminal of the first operational amplifier is connected to the capacitor. C 1. Series connection, capacitor C 1 and resistance R amp3 Series, Ramp3 , R amp4 , C 2 and the second operational amplifier constitute an integrating and restoring circuit, and R amp3 Connect to the negative input terminal of the second operational amplifier.

[0070] This invention provides a unified sensitivity characterization method for non-invasive current detection scenarios. By explicitly incorporating factors such as three-dimensional magnetic field distribution, core attitude, core spatial position, core cross-sectional shape, and frequency into the sensitivity function, the sensitivity of the sensor at any position and angle can be calculated. This avoids the limitations of relying on specific structures or empirical calibration, providing a unified characterization standard for sensitivity analysis in different application scenarios. The constructed sensitivity function of the non-invasive current sensor does not limit the conductor of the measured current to a line current or a specific geometric structure, and is applicable to complex current-carrying and non-uniform magnetic field environments such as converters, power electronic devices, and busbar monitoring. It has good structure independence and a wide range of applications.

[0071] Example 2 Based on the above embodiments, optionally, when the conductor of the measured current is a long straight circular wire, the amplitude of the spatial magnetic field is only related to the magnitude of the measured current in the conductor and the geometric distance between the non-invasive current sensor and the conductor, and the sensitivity function is expressed as:

[0072] The cross-section of the long straight circular conductor has a radius of... R A circle, the length of which is along z Extending along the axial direction; μ 0 represents the permeability of air. ρ This is the radial distance from the observation point to the axis of the circular traverse.

[0073] This embodiment uses a long, straight, round wire as the conductor and an induction coil wound on a linear magnetic core as the non-invasive current sensor structure. It explains how, under the condition of a round wire, the measured current... i to sensor output voltage v o The complete modeling process.

[0074] Unlike Example 1, in this example, the conductor carrying the measured current is an axisymmetric circular conductor with a circularly symmetrical cross-section. The external magnetic field is determined solely by the measured current and is independent of the internal current distribution. The current frequency does not affect the external magnetic field. B / i Since the frequency remains constant, the mapping relationship between the measured current and the spatial magnetic field can be directly established, thus simplifying the modeling process.

[0075] like Figure 10As shown, the conductor is a long, straight, circular wire with a cross-section of radius [radius value missing]. R The circle, the length of the conductor along z Extending along the axial direction, the measured current i along z Flow in the axial direction.

[0076] Under this assumption, any distance around the circular conductor is ρ At a given point in space, the magnetic field distribution can be directly obtained from the Biot-Savart law, and its magnetic induction amplitude is: (twenty three) in, μ 0 represents the permeability of air. ρ This is the radial distance from the observation point to the axis of the circular traverse.

[0077] As can be seen from equation (23), under this model, the amplitude of the spatial magnetic field is only related to the magnitude of the measured current and the geometric distance between the sensor and the conductor, and is independent of the specific distribution of the current density inside the conductor. In this embodiment, the magnetic field model is applicable to conductor structures with single-core conductors and circular cross-sections.

[0078] After obtaining the spatial magnetic field distribution around the circular conductor, the projection of the spatial magnetic field onto the main axis of the magnetic core, the calculation of the effective magnetic flux within the magnetic core, the acquisition of the coil induced voltage, and the integration processing of the induced voltage by the signal restoration circuit are all the same as those described in Example 1, and will not be repeated here.

[0079] The same steps can be used to measure the current. i To output voltage v o The complete modeling process was established, and based on this, the sensitivity function of the non-invasive current sensor under the condition of a circular conductor was established.

[0080] In this specific embodiment, the sensitivity function is: (twenty four) The sensitivity function provided in this embodiment of the invention is the same as the sensitivity function provided in Embodiment 1, and can calculate the sensitivity of the sensor at any position and angle; it avoids the limitations of relying on specific structures or empirical calibration, and provides a unified characterization standard for sensitivity analysis in different application scenarios.

[0081] Example 3 The present invention also provides a unified sensitivity characterization device for non-invasive current detection scenarios, comprising: The current density calculation module is used to establish a three-dimensional coordinate system with the measured current in the conductor as the research object, the current direction of the measured current as the z-axis, and the plane where the cross-section of the conductor is located as the xy plane, thereby establishing a model of the measured current density distribution inside the conductor. The spatial magnetic field distribution calculation module is used to calculate the three-dimensional spatial magnetic field distribution outside the conductor based on the current density distribution model. The effective magnetic flux calculation module is used to combine the three-dimensional spatial structure model of the non-invasive current sensor, project the three-dimensional spatial magnetic field distribution along the sensor's principal axis to obtain the effective magnetic induction intensity; and integrate the effective magnetic induction intensity on the effective cross section of the magnetic core to obtain the effective magnetic flux. The sensing voltage module is used to differentiate the effective magnetic flux and calculate the coil sensing voltage in the non-invasive current sensor. The sensitivity function construction module is used to integrate the coil induced voltage through the signal restoration circuit to obtain an output voltage proportional to the effective magnetic flux, thereby obtaining the sensitivity function of the non-invasive current sensor. The sensitivity function is expressed as:

[0082] in, f The operating frequency of the current being measured in the conductor; This describes the distribution of the measured current in the conductor. r ′ is the position vector of any point within the conductor's cross-section; r This is the position vector of the magnetic core of the non-invasive current sensor in space. is the unit vector along the principal axis of the magnetic core; μ eff The effective permeability of the magnetic core; A core This represents the effective cross-sectional area of ​​the magnetic core. K It is the proportional coefficient of the signal restoration circuit; N This represents the number of turns in the coil.

[0083] The sensitivity uniform characterization method for non-invasive current detection scenarios provided in this embodiment of the invention is used to perform the sensitivity uniform characterization method for non-invasive current detection scenarios as described in Embodiment 1 or Embodiment 2, and has the same beneficial effects.

[0084] Example 4 Based on the above embodiments, the present invention also provides a non-invasive current sensor, wherein the sensitivity of the non-invasive current sensor in a non-invasive current detection scenario is represented by a unified sensitivity characterization method for non-invasive current detection scenarios as described in any one of Embodiment 1.

[0085] The non-invasive current sensor provided in this embodiment of the invention can be used to represent the sensitivity of any shape and material using the sensitivity characterization method in Embodiment 1, and the accuracy is the same.

[0086] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A unified sensitivity characterization method for non-invasive current detection scenarios, characterized in that, include: Taking the measured current in the conductor as the research object, the current direction of the measured current as the z-axis, and the plane where the cross-section of the conductor is located as the xy plane, a three-dimensional coordinate system is established to establish a model of the measured current density distribution inside the conductor. The three-dimensional spatial magnetic field distribution outside the conductor is calculated based on the current density distribution model. By combining the three-dimensional spatial structure model of the non-invasive current sensor, the three-dimensional spatial magnetic field distribution is projected along the sensor's principal axis to obtain the effective magnetic induction intensity; the effective magnetic induction intensity is then integrated on the effective cross-section of the magnetic core to obtain the effective magnetic flux. The effective magnetic flux is differentiated to calculate the coil induced voltage in the non-invasive current sensor; The coil-induced voltage is integrated by a signal restoration circuit to obtain an output voltage proportional to the effective magnetic flux, thereby obtaining the sensitivity function of the non-invasive current sensor. The sensitivity function is expressed as: in, f The operating frequency of the current being measured in the conductor; This describes the distribution of the measured current in the conductor. r ′ is the position vector of any point within the conductor's cross-section; r This is the position vector of the magnetic core of the non-invasive current sensor in space. is the unit vector along the principal axis of the magnetic core; μ eff The effective permeability of the magnetic core; A core This represents the effective cross-sectional area of ​​the magnetic core. K It is the proportional coefficient of the signal restoration circuit; N This represents the number of turns in the coil.

2. The method as described in claim 1, characterized in that, The method of establishing a current density distribution model inside a conductor, taking the measured current in the conductor as the research object, includes: At frequency f Under operating conditions, the measured current density inside the conductor Due to the skin effect, the electromagnetic diffusion equation is satisfied: in, ω =2π f Angular frequency, μ For the conductor's permeability, σ The conductivity of a conductor; Based on the constraint that the measured current density distribution inside the conductor is consistent with the measured current in the conductor, the current density is normalized to obtain the measured current from the conductor. i Current density distribution inside the conductor The mapping relationship; The constraints are as follows: in, dS source Let be the area of ​​a small element of the conductor's cross-section. S source The cross-sectional area of ​​the conductor to be measured current; The solution yields the measured current density distribution function inside the conductor as a function of frequency. .

3. The method as described in claim 2, characterized in that, The calculation of the three-dimensional spatial magnetic field distribution outside the conductor based on the measured current density distribution model includes: Based on the Biot-Savart law, the measured current of the conductor is established according to the current density distribution model. i The distribution of the three-dimensional magnetic field at any point in space: in, The measured current density inside the conductor. For frequency f Lower spatial position r Magnetic flux density at the location; V This indicates the volume area occupied by the sensor.

4. The method as described in claim 3, characterized in that, The three-dimensional spatial structure model combined with the non-invasive current sensor is used to project the three-dimensional spatial magnetic field distribution along the sensor's principal axis to obtain the effective magnetic flux density. The effective magnetic flux density is then integrated across the effective cross-section of the magnetic core to obtain the effective magnetic flux, including: Based on the magnetic core position parameters of the non-invasive current sensor r c Attitude parameters Magnetic core permeability characteristics μ r、 Effective permeability μ eff and effective cross-sectional area A core Parameters were used to establish a three-dimensional spatial structure model of the non-invasive current sensor; Let the direction of the sensor core spindle be... The three-dimensional spatial magnetic field distribution is projected onto the main axis of the magnetic core: Among them, the direction of the main axis of the sensor core is the attitude parameter; Permeability obtained from the core material datasheet Real permeability Imaginary permeability , And through geometric demagnetization factor N d Effective permeability is obtained: in, N d It is related to the shape and size of the magnetic core; Based on the complex permeability of the magnetic core and the cross-sectional area of ​​the magnetic core A core The effective magnetic flux is obtained by integrating the effective magnetic induction intensity over the effective cross-section of the magnetic core. 。 5. The method as described in claim 4, characterized in that, The expression for the coil-induced voltage is: 。 6. The method as described in claim 5, characterized in that, The expression for the output voltage is: ； in, K It is the proportional coefficient of the transfer function in the signal restoration circuit, which is determined by the resistors, capacitors, and operational amplifier parameters in the signal restoration circuit.

7. The method as described in claim 1, characterized in that, When the conductor is a long, straight, circular wire, the amplitude of the spatial magnetic field depends only on the magnitude of the current being measured on the conductor and the geometric distance between the non-invasive current sensor and the conductor. The sensitivity function is expressed as: Among them, the cross-section of the long straight circular conductor has a radius of... R A circle, the length of which is along z Extending along the axial direction; μ 0 represents the permeability of air. ρ This is the radial distance from the observation point to the axis of the circular conductor.

8. A unified sensitivity characterization device for non-invasive current detection scenarios, characterized in that, include: The current density calculation module is used to establish a three-dimensional coordinate system with the measured current in the conductor as the research object, the current direction of the measured current as the z-axis, and the plane where the cross-section of the conductor is located as the xy plane, thereby establishing a model of the measured current density distribution inside the conductor. The spatial magnetic field distribution calculation module is used to calculate the three-dimensional spatial magnetic field distribution outside the conductor based on the current density distribution model. The effective magnetic flux calculation module is used to combine the three-dimensional spatial structure model of the non-invasive current sensor, project the three-dimensional spatial magnetic field distribution along the sensor's principal axis to obtain the effective magnetic induction intensity; and integrate the effective magnetic induction intensity on the effective cross section of the magnetic core to obtain the effective magnetic flux. The sensing voltage module is used to differentiate the effective magnetic flux and calculate the coil sensing voltage in the non-invasive current sensor. The sensitivity function construction module is used to integrate the coil induced voltage through the signal restoration circuit to obtain an output voltage proportional to the effective magnetic flux, thereby obtaining the sensitivity function of the non-invasive current sensor. The sensitivity function is expressed as: in, f The operating frequency of the current being measured in the conductor; This describes the distribution of the measured current in the conductor. r This is the position vector of the magnetic core of the non-invasive current sensor in space. is the unit vector along the principal axis of the magnetic core; μ eff The effective permeability of the magnetic core; A core This represents the effective cross-sectional area of ​​the magnetic core. K It is the proportional coefficient of the signal restoration circuit; N This represents the number of turns in the coil.

9. A non-invasive current sensor, characterized in that, In non-invasive current detection scenarios, the sensitivity of the non-invasive current sensor is represented by the unified sensitivity characterization method for non-invasive current detection scenarios as described in any one of claims 1-7.

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