Coreless sensor array precision correction device and method

Abstract

This invention proposes a coreless sensor array accuracy calibration device and method. A three-phase AC source is designed as the system power supply. Current flowing through three loads generates three different magnetic fields. An operational amplifier, an analog-to-digital converter, and a host computer are used for data acquisition and analysis to evaluate the measurement accuracy of the coreless sensor array. By securing the coreless circular sensor array under test to the calibrator, the accuracy of the coreless circular sensor array can be calibrated.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power measurement, and in particular to a device and method for calibrating the accuracy of a coreless sensor array. Background Art

[0002] Electromagnetic induction is a fundamental measurement technology in modern power systems, with applications ranging from residential and industrial to public utilities. Non-contact measurement of current in a bundle of conductors has always been a challenging task. With the advancement of semiconductor technology, coreless sensor arrays have been used for current measurement.

[0003] For coreless sensor arrays, the principle is to use mathematical methods to estimate the current value of the conductor based on the magnetic field values ​​sensed by multiple magnetic field sensors. This means that the influence of position and material properties cannot be ignored. Summary of the Invention

[0004] The present invention addresses the defects and shortcomings of the prior art and proposes a coreless sensor array precision calibration device and method. A special corrector design is provided, and based on this, a matching precision calibration method is proposed.

[0005] The specific technical solutions are as follows:

[0006] A coreless sensor array precision calibration device employs a calibrator consisting of a concentric frustum and a square base. The calibrator has 13 holes through which a current guide rod passes, generating a circular magnetic field when current flows through the rod. One of the 13 holes is located at the center of the frustum, eight holes are equidistantly arranged on a circle a certain distance from the center, with angles of 45° between them, and four holes are located at the vertices of a square outside the circle, on extensions of four of the holes relative to the center of the circle.

[0007] During precision calibration, the coreless sensor array is nested and fixed on the circular table of the corrector and is parallel to the square base.

[0008] Furthermore, one end of the guide rod is connected to a three-phase AC source, and the other end is grounded via a load; a current sensor is provided on the guide rod, and the coreless sensor array is connected to an amplifier, and both are connected to a data acquisition device via an analog-to-digital converter.

[0009] A coreless sensor array precision calibration method, using the coreless sensor array precision calibration device as described above;

[0010] The change of the spatial magnetic field caused by the current flowing through the guide rod is described by the Biot-Savart law;

[0011] Set all current values ​​I1, I2, I3, ...In The currents flowing through the guide rods in the 13 through-holes are all equal and used to calibrate the coreless sensor array:

[0012]

[0013] Wherein, the subscript n represents the number of the sensor s in the coreless sensor array, m represents the number of the guide rod, 1 refers to the distance, α refers to the angle between the magnetic field generated by the current in the guide rod and the magnetic field of the sensor, and Δ is the error between the calculation and the actual value.

[0014]

[0015] Where μ0 represents the vacuum permeability, μ0 = 4π × 10^-7Wb / (A·m), and I refers to the current;

[0016] The optimal solution is obtained by continuously superimposing the formula (1) by the least square method, and finally, a value Δα closest to the error is obtained. V and Δl V , and inversely deduce B through the formula v , B v for:

[0017]

[0018] Among them, the subscripts V and v mean:

[0019] It and the magnetic field sensor sense the magnetic field B s The difference ratio is the sensor error, and the error S is:

[0020]

[0021] The accuracy of the coreless circular sensor array is corrected by performing error compensation.

[0022] Furthermore, in the process of continuously superimposing the calculation of formula (1) by the least square method, restriction conditions are added to improve the solution speed.

[0023] Furthermore, the restriction conditions include angle error restriction and distance error restriction.

[0024] The present invention and its preferred embodiment achieve high-precision and convenient calibration of a coreless sensor array. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0026] Figure 1 Schematic diagram of the overall structure of the device according to the embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the perforation arrangement structure of an embodiment of the present invention;

[0028] Figure 3 It is a schematic diagram of the principle of the correction method of an embodiment of the present invention. DETAILED DESCRIPTION

[0029] To make the features and advantages of this patent more clearly understood, the following embodiments are specifically described in detail with reference to the accompanying drawings:

[0030] In this embodiment, a three-phase AC source is designed as the system power supply, and the current flowing through the three loads can generate three different magnetic fields. Operational amplifiers, analog-to-digital converters, and host computers are used for data acquisition and data analysis to evaluate the measurement accuracy of the coreless sensor array. By fixing the coreless circular sensor array to be measured on the calibrator, the accuracy of the coreless circular sensor array can be calibrated, as shown in the schematic diagram. Figure 1 shown.

[0031] The corrector in this embodiment is composed of a 3D-printed high-precision truncated cone and a square base. The cone and the square base share a common center and have 13 holes from top to bottom. The guide rod can be firmly inserted through them. When current flows through the guide rod, it will generate a circular magnetic field around it according to Ampere's loop theorem. One hole is located at the center of the cone, and eight holes are located on a circle with a certain size from the center, with an angle of 45°. A square maximum hole is added outside each 45°, for a total of 4 holes, such as Figure 2 The corrector can be nested with the coreless circular array so that it can be fixed effectively and parallel to it, thereby determining the positional relationship between each element and providing support for subsequent correction algorithms.

[0032] In this embodiment, the change in the spatial magnetic field caused by the current flowing through the wire can be described using the Biot-Savart law. The magnetic field sensor sensing situation can be described as:

[0033]

[0034]

[0035] like Figure 3 As shown, α 11 To calculate the angle between the magnetic field generated by the current I1 and the magnetic field of the sensor S1, Δα 11 The angle error between the calculated and actual values ​​is l 11 To calculate the distance between current I1 and sensor S1, Δl 11 is the distance error between the calculated and actual distance. 12 To calculate the angle between the magnetic field generated by the current I2 and the magnetic field of the sensor S1, Δα 12The angle error between the calculated and actual values ​​is l 12 To calculate the distance between current I2 and sensor S1, Δl 12 The error between the calculated and actual distance.

[0036] Since when the currents I1 and I2 are set equal, they can be described as:

[0037]

[0038] Therefore, the magnetic field of the current flowing through each individual through-hole conductor can be described as:

[0039]

[0040] Similarly, the currents flowing through the conductors in the 13 through-holes are used to calibrate the coreless sensor array. When all current values ​​I1, I2, I3, ... I n are equal. The formula can be expanded to:

[0041]

[0042] The optimal solution can be obtained by continuously superimposing the least squares method. In the solution, the speed of solution can be improved by adding constraints such as angle error not exceeding 2°, distance error not exceeding 3mm, etc. Finally, a value Δα closest to the error can be obtained. v and Δl v , and B can be deduced through the formula v , B v It can be described as:

[0043]

[0044] It and the magnetic field sensor sense the magnetic field B s The difference ratio is the sensor error, and the error S can be described as:

[0045]

[0046] Therefore, the accuracy of the coreless circular sensor array can be improved by performing error compensation.

[0047] This patent is not limited to the above-mentioned optimal implementation mode. Anyone can derive various other forms of coreless sensor array precision calibration devices and methods based on the inspiration of this patent. All equivalent changes and modifications made within the scope of the patent application of this invention should be covered by this patent.

Claims

1. A coreless sensor array precision calibration device, characterized by: A corrector comprising a concentric frustum and a square base; the corrector has 13 holes through which the current guide rod passes, so that a circular magnetic field is generated when current flows through the current guide rod; one of the 13 holes is located at the center of the frustum, eight holes are equidistantly arranged on a circle of a predetermined size from the center, at 45° angles to each other, and four holes are located at the vertices of a square outside the circle, on the extension lines of four of the holes relative to the center of the circle. During precision calibration, the coreless sensor array is nested and fixed on the circular table of the corrector and is parallel to the square base; One end of the guide rod is connected to a three-phase AC source, and the other end is grounded via a load; a current sensor is provided on the guide rod, and the coreless sensor array is connected to an amplifier, and both are connected to a data acquisition device via an analog-to-digital converter; The correction methods include: The change of the spatial magnetic field caused by the current flowing through the guide rod is described by the Biot-Savart law; Set the current values ​​of all guide rods to be equal; The optimal solution is obtained by superimposing the least square method with angle error limit and distance error limit; The error compensation is performed based on the inverse calculation of the theoretical magnetic field value based on the optimal solution.

2. The coreless sensor array precision calibration device according to claim 1, characterized in that: The specific implementation process of the correction method includes: Set all current values ​​I1, I2, I3, ...I n The currents flowing through the guide rods in the 13 through-holes are all equal and used to calibrate the coreless sensor array: （1） Wherein, the subscript n represents the number of the sensor s in the coreless sensor array, m represents the number of the guide rod, l refers to the distance, and α refers to the angle between the magnetic field generated by the current in the guide rod and the magnetic field of the sensor. is the error between calculation and actual; （2） in, Represents vacuum permeability, μ0=4π×10^-7Wb / (A·m), I refers to current; The optimal solution is obtained by continuously superimposing the formula (1) by the least square method, and finally, a value closest to the error is obtained. and , and deduced through the formula , for: （3） It and the magnetic field sensor sense the magnetic field B s The difference ratio is the sensor error, and the error S is: （4） The accuracy of the coreless circular sensor array is corrected by performing error compensation.

3. The coreless sensor array precision calibration device according to claim 2, characterized in that: In the process of continuously superimposing the calculation of formula (1) by the least square method, the solution speed is improved by adding restriction conditions.

4. The coreless sensor array precision calibration device according to claim 2, characterized in that: The constraints include angle error limit and distance error limit.

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