High-precision three-dimensional alternating current magnetic field detection system and method

Abstract

The invention provides a high-precision three-dimensional alternating-current magnetic field detection system and method, and the system comprises a coil signal detection module which employs a three-dimensional coil to obtain an original signal of an alternating-current magnetic field; the signal amplification module is used for carrying out amplification processing on the alternating current magnetic field original signal by adopting an instrument amplifier; the signal processing and analyzing module is used for carrying out analog-to-digital conversion processing and converting the amplified alternating-current magnetic field signal into a digital signal; and determining the magnetic field intensity and the magnetic field direction of the alternating current magnetic field around the PCB according to the corresponding relationship between the digital signal and the alternating current magnetic field intensity. An optimized coil design, an efficient signal conversion circuit and an accurate signal measuring and processing algorithm are adopted, weak signals in the alternating current magnetic field can be accurately captured and converted, useful information is extracted through a digital signal processing technology, and accurate measurement and analysis of parameters such as distribution of the alternating current magnetic field around the intelligent electric meter are achieved.

Description

Technical Field

[0001] The present invention relates to the field of AC magnetic field detection by intelligent electric energy meters, and in particular to a high-precision and high-sensitivity AC magnetic field detection system and method. Background Art

[0002] With the increasing demand for anti-electricity theft in smart electricity meters, traditional AC magnetic field detection methods are often limited by problems such as detection magnetic field strength, sensitivity, and detection speed; they are unable to accurately identify and measure the surrounding AC magnetic field strength and direction, resulting in inaccurate meter measurement results; and it is difficult to meet high-precision and high-efficiency detection requirements.

[0003] Therefore, developing a method that can detect three-dimensional AC magnetic fields with high precision in complex electromagnetic environments is of great significance for improving the reliability of smart meters and the stability of power systems. Summary of the invention

[0004] The present invention aims to provide a high-sensitivity and high-precision AC magnetic field detection system and method, which realizes high-precision and high-sensitivity detection of AC magnetic fields by optimizing coil structure design and combining signal conversion and measurement technology.

[0005] The technical solution of the present invention is:

[0006] The present invention provides a high-precision three-dimensional alternating current magnetic field detection system, the system comprising:

[0007] A coil signal detection module, comprising a three-dimensional coil, a SMD manganese copper resistor R3 and an anti-aliasing filter circuit, wherein the three-dimensional coil is arranged on a PCB board, and both ends of the three-dimensional coil are connected to the SMD manganese copper resistor R3, for obtaining an original AC magnetic field signal, and the anti-aliasing filter circuit performs anti-aliasing filtering on the original AC magnetic field signal to remove high-frequency interference signals in the original AC magnetic field signal;

[0008] The signal amplification module uses an instrument amplifier to amplify the original AC magnetic field signal to obtain an amplified AC magnetic field signal;

[0009] The signal processing and analysis module performs analog-to-digital conversion on the amplified AC magnetic field signal to convert the amplified AC magnetic field signal into a digital signal; and determines the magnetic field strength and magnetic field direction of the AC magnetic field around the PCB board according to the corresponding relationship between the digital signal and the AC magnetic field strength.

[0010] Further, the three-dimensional coil includes a first coil, a second coil and a third coil which are arranged perpendicular to each other;

[0011] The first coil is parallel to the PCB board;

[0012] The second coil is perpendicular to the first coil and perpendicular to the PCB board;

[0013] The third coil is perpendicular to the first coil and the second coil.

[0014] Further, the anti-aliasing filter circuit includes resistors R1, R2, R4, R5 and capacitors C1, C2;

[0015] One end of the three-dimensional coil is connected to resistor R3_1, the other end of the three-dimensional coil is connected to resistor R3_2, resistor R2_2 is connected to resistor R3_1, resistor R2_1 is connected to GND, resistor R4_1 is connected to resistor R3_2, resistor R4_2 is connected to resistor R2_1, resistor R1_1 is connected to resistor R2_2, resistor R1_2 is connected to capacitor C1_1, capacitor C1_2 is connected to capacitor C2_1, capacitor C2_2 is connected to resistor R5_2, and resistor R5_1 is connected to resistor R4_1.

[0016] Further, the instrument amplifier includes operational amplifiers U2A, U2B and U3B, resistors R7, RG, R9-R13;

[0017] The operational amplifiers U2A, U3B and resistors R7, RG, R9 constitute a preamplifier circuit;

[0018] The operational amplifier U2B and R10-R13 constitute a differential amplifier circuit;

[0019] Among them, operational amplifier U2A_2 is connected to capacitor C1_1, operational amplifier U2A_3 is connected to resistor R7_2, operational amplifier U2A_1 is connected to resistor R7_1, operational amplifier U3B_2 is connected to resistor R9_1, operational amplifier U3B_3 is connected to capacitor C2_2, operational amplifier U3B_1 is connected to resistor R9_2, resistor RG_1 is connected to resistor R7_2, resistor RG_2 is connected to resistor R9_1, resistor R12_1 is connected to resistor R7_1, resistor R10_1 is connected to resistor R9_2, operational amplifier U2B_2 is connected to resistor R12_2, operational amplifier U2B_3 is connected to resistor R10_2, resistor R13_1 is connected to resistor R12_2, resistor R11_1 is connected to resistor R10_2, resistor R11_2 is connected to GND, and resistor R13_2 is connected to operational amplifier U2B_1.

[0020] A high-precision three-dimensional alternating current magnetic field detection method, based on the system, the method comprises:

[0021] The original signal of the AC magnetic field is obtained by a three-dimensional coil and a SMD manganese copper resistor R3 arranged on the PCB board, wherein the three-dimensional coil includes a first coil, a second coil and a third coil arranged perpendicularly to each other, and both ends of the three-dimensional coil are connected to the SMD manganese copper resistor R3;

[0022] Amplifying the original AC magnetic field signal to obtain an amplified AC magnetic field signal;

[0023] Performing analog-to-digital conversion processing on the amplified AC magnetic field signal to convert the amplified AC magnetic field signal into a digital signal; determining the magnetic field strength and magnetic field direction of the AC magnetic field around the PCB board according to the corresponding relationship between the digital signal and the AC magnetic field strength;

[0024] If the magnetic field strength exceeds a preset threshold, it is determined that electricity theft occurs around the smart meter.

[0025] Furthermore, the voltage across the chip manganese copper resistor R3 satisfies the following formula:

[0026] VP-VN=(B×S / μ0N)×R3

[0027] Where: Φ is the magnetic flux, B is the magnetic field strength, S is the coil area, μ0 is the vacuum permeability, N is the number of coil turns, and I is the current in the coil.

[0028] Furthermore, the amplified AC magnetic field signal Vo satisfies the following formula:

[0029] Vo=

R13×S×R3×(R7+R9+RG)×B

[0030] Where: B is the magnetic field strength, S is the coil area, μ0 is the vacuum magnetic permeability, N is the number of coil turns, R3 is the resistance of the chip manganese copper resistor, R7, R9, RG, R12 and R13 are the resistance values ​​of the signal amplifier module resistors respectively.

[0031] Furthermore, the analog-to-digital conversion processing of the amplified AC magnetic field signal includes:

[0032] The amplified AC magnetic field signal is quantized and encoded to obtain a digital quantized signal;

[0033] The digital quantization signal is subjected to root mean square filtering, and a direct current component in the digital quantization signal is extracted as the digital signal.

[0034] Further, determining the magnetic field strength and magnetic field direction of the AC magnetic field around the PCB board according to the corresponding relationship between the digital signal and the AC magnetic field strength includes:

[0035] Determine the component size of the AC magnetic field around the PCB board in the X-axis direction according to the digital signal obtained by the first coil;

[0036] Determine the component size of the AC magnetic field around the PCB board in the Y-axis direction according to the digital signal obtained by the second coil;

[0037] Determine the component size of the alternating magnetic field around the PCB board in the Z-axis direction according to the digital signal obtained by the third coil;

[0038] The magnetic field intensity and magnetic field direction of the AC magnetic field around the PCB board are calculated according to the component in the X-axis direction, the component in the Y-axis direction, and the component in the Z-axis direction.

[0039] Furthermore, the corresponding relationship between the digital signal and the AC magnetic field strength satisfies the following formula:

[0040] VD=

R13×S×R3×(R7+R9+RG)×B

[0041] Where: VD is the digital signal amplitude, K is the ADC conversion coefficient.

[0042] Beneficial effects of the present invention:

[0043] The system of the present invention significantly improves the detection sensitivity by optimizing the coil structure and converting signal processing, adopts a low-noise instrument amplifier and digital signal processing to effectively reduce noise interference, improve the quality of the detection signal, and facilitate AC magnetic field signal processing; by detecting the AC magnetic field in all directions, the magnitude and direction of the magnetic field intensity can be detected and judged, effectively improving the accuracy requirements of the smart electric energy meter for preventing electricity theft.

[0044] The present invention discloses a high-precision three-dimensional AC magnetic field detection system and method. The method obtains the AC magnetic field signal around the PCB board by setting a three-dimensional coil, and performs anti-aliasing filtering, amplification and analog-to-digital conversion processing on the signal; then, the DC component in the digital signal is extracted by the root mean square filtering method, and the magnetic field strength and direction are calculated according to the magnetic field components in three directions. When the magnetic field strength exceeds the preset threshold, it is determined that there is electricity theft.

[0045] The present invention solves the problem that traditional anti-electricity theft methods are difficult to accurately detect weak magnetic field changes. Through multi-dimensional magnetic field signal acquisition and processing, the accuracy and sensitivity of electricity theft detection are improved. At the same time, the method can also effectively suppress environmental interference and reduce false alarm rates, providing reliable protection for the safe operation of smart grids.

[0046] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0048] Figure 1 A diagram of a high-precision three-dimensional AC magnetic field detection system according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0049] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0050] Example 1

[0051] Figure 1 A diagram of a high-precision three-dimensional AC magnetic field detection system according to an embodiment of the present invention is shown.

[0052] like Figure 1 As shown, the present invention proposes a high-precision three-dimensional AC magnetic field detection system, which mainly includes an optimized coil design, an efficient signal conversion circuit, and precise signal measurement and processing. It can accurately capture and convert weak signals in the AC magnetic field, extract useful information through digital signal processing technology, and realize precise measurement and analysis of parameters such as the AC magnetic field distribution around the smart meter.

[0053] The present invention is based on Faraday's law of electromagnetic induction and detects changes in the magnetic field through the induced current of the coil in the AC magnetic field. When the system is working, the excitation source generates an alternating magnetic field, and an alternating current is generated through the coil. The two ends of the coil are connected to a high-precision patch manganese copper, so that a weak voltage signal is detected at both ends of the manganese copper. After amplification and processing, the signal is used to analyze the characteristics of the AC magnetic field, including the magnetic field strength and magnetic field direction, where;

[0054] Coil signal detection module: Figure 1 As shown, it includes a first coil, a second coil and a third coil, wherein the first coil is parallel to the PCB, the third coil is perpendicular to the left side of the first coil, and the second coil is perpendicular to the bottom of the first coil. R3 is a patch manganese copper, which can realize three-dimensional AC magnetic field detection, according to:

[0055] Φ=B×S Formula 1

[0056] Φ=μ0NI Formula 2

[0057] Among them, Φ is the magnetic flux, B is the magnetic field strength, S is the coil area, μ0 is the vacuum magnetic permeability, N is the number of coil turns, and I is the current in the coil. According to Formula 1 and Formula 2, the relationship between the magnetic field strength and the coil current is:

[0058] I=B×S / μ0N Formula 3

[0059] According to formula 3, the voltage across the manganese copper is:

[0060] VP-VN=(B×S / μ0N)×R3 Formula 4.

[0061] Specifically, the signal detection module also includes an anti-aliasing circuit composed of R1, R2, R4, R5, C1, and C2 to improve the quality of the original signal.

[0062] Signal amplification module: A low-noise instrumentation amplifier is used to design the preamplifier circuit to preliminarily amplify the weak signal output by the coil and effectively suppress noise. The signal amplification part is composed of op amps U2A, U2B, U3B, resistors R7, RG, R9, R10, R11, R12, and R13 to form an instrumentation amplifier to amplify the sampled manganese copper signal, where R7=R9, R11=R13, and R12=R10.

[0063] According to the virtual short and virtual disconnection of the op amp input terminal, we can get:

[0064] (V01-V02) / (R7+R9+RG)=(VP-VN) / RG Formula 5

[0065] The resistors R10, R11, R12, R13, and U2B form a differential amplifier, and the relationship between input and output is:

[0066] Vo=R13×(V01-V02) / R12Formula 6

[0067] According to Formula 4, Formula 5, and Formula 6, the relationship between the instrumentation amplifier output voltage Vo and the magnetic field strength B is calculated as follows:

[0068] Vo=

R13×S×R3×(R7+R9+RG)×B

[0069] Signal processing and analysis module: Using a high-precision analog-to-digital converter, U1 converts the analog signal into a digital signal. Before ADC conversion, the analog signal is first filtered. The filtering method uses the root mean square filtering method to effectively remove the high-frequency noise in the signal and extract the useful analog signal in the AC magnetic field. The specific steps are as follows:

[0070] 1. The high-precision analog-to-digital converter U1 samples the amplified analog signal, and the sampling frequency is high enough to ensure that the signal is not distorted.

[0071] 2. Square the sampled digital signal and add the results. Divide the sum of squares by the number of sampling points to get the mean of the signal.

[0072] 3: Take the square root of the mean value to obtain the RMS value of the signal, and use the RMS value as the filtered analog signal for ADC conversion.

[0073] Assume that the digital signal after the analog signal Vo is converted by ADC is VD, and the conversion coefficient is K. Then the digital signal after ADC conversion is:

[0074] VD=

R13×S×R3×(R7+R9+RG)×B

[0075] According to Formula 8, the relationship between the magnetic field strength and the converted digital signal can be obtained to determine the magnitude and direction of the magnetic field strength in the environment around the smart meter.

[0076] Example 2

[0077] The present invention provides a high-precision three-dimensional alternating current magnetic field detection method. Based on the system, the method comprises:

[0078] Step S1, obtaining an AC magnetic field signal; setting a three-dimensional coil, wherein the three-dimensional coil includes a first coil, a second coil and a third coil, wherein the first coil is parallel to a PCB board, the second coil is perpendicular to the first coil and perpendicular to the PCB board, and the third coil is perpendicular to the first coil and the second coil, and the three-dimensional coil is used to obtain an AC magnetic field signal around the PCB board.

[0079] Step S2, performing anti-aliasing filtering on the AC magnetic field signal to obtain a filtered signal: using a filtering circuit composed of a resistor and a capacitor to perform anti-aliasing filtering on the AC magnetic field signal to remove high-frequency interference in the AC magnetic field signal to obtain a filtered signal.

[0080] Step S3, amplifying the filtered signal to obtain an amplified analog signal: using a low-noise instrumentation amplifier to amplify the filtered signal to obtain an amplified analog signal.

[0081] Step S4, performing analog-to-digital conversion on the amplified analog signal to obtain a digital signal.

[0082] Step S5: filter the digital signal using a root mean square filtering method.

[0083] Step S6, determining the component size of the AC magnetic field around the PCB board in the X-axis direction according to the digital signal obtained by the first coil;

[0084] Determine the magnitude of the component of the alternating magnetic field around the PCB board in the Y-axis direction according to the digital signal acquired by the second coil;

[0085] The magnitude of the component of the alternating magnetic field around the PCB board in the Z-axis direction is determined according to the digital signal acquired by the third coil.

[0086] Step S7, obtaining the magnetic field strength and magnetic field direction of the AC magnetic field around the PCB board according to the magnetic field components in the X-axis direction, the Y-axis direction, and the Z-axis direction; if the magnetic field strength exceeds a preset threshold, it is determined that electricity theft exists around the smart meter.

[0087] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A high-precision three-dimensional AC magnetic field detection system, characterized in that: The system includes: A coil signal detection module, comprising a three-dimensional coil, a SMD manganese copper resistor R3 and an anti-aliasing filter circuit, wherein the three-dimensional coil is arranged on a PCB board, and both ends of the three-dimensional coil are connected to the SMD manganese copper resistor R3, for obtaining an original AC magnetic field signal, and the anti-aliasing filter circuit performs anti-aliasing filtering on the original AC magnetic field signal to remove high-frequency interference signals in the original AC magnetic field signal; The signal amplification module uses an instrument amplifier to amplify the original AC magnetic field signal to obtain an amplified AC magnetic field signal; The signal processing and analysis module performs analog-to-digital conversion on the amplified AC magnetic field signal to convert the amplified AC magnetic field signal into a digital signal; and determines the magnetic field strength and magnetic field direction of the AC magnetic field around the PCB board according to the corresponding relationship between the digital signal and the AC magnetic field strength.

2. The high-precision three-dimensional AC magnetic field detection system according to claim 1, characterized in that: The three-dimensional coil comprises a first coil, a second coil and a third coil which are arranged perpendicular to each other; The first coil is parallel to the PCB board; The second coil is perpendicular to the first coil and perpendicular to the PCB board; The third coil is perpendicular to the first coil and the second coil.

3. The high-precision three-dimensional AC magnetic field detection system according to claim 1, characterized in that: The anti-aliasing filter circuit includes resistors R1, R2, R4, R5 and capacitors C1, C2; One end of the three-dimensional coil is connected to resistor R3_1, the other end of the three-dimensional coil is connected to resistor R3_2, resistor R2_2 is connected to resistor R3_1, resistor R2_1 is connected to GND, resistor R4_1 is connected to resistor R3_2, resistor R4_2 is connected to resistor R2_1, resistor R1_1 is connected to resistor R2_2, resistor R1_2 is connected to capacitor C1_1, capacitor C1_2 is connected to capacitor C2_1, capacitor C2_2 is connected to resistor R5_2, and resistor R5_1 is connected to resistor R4_1.

4. The high-precision three-dimensional AC magnetic field detection system according to claim 3, characterized in that: The instrument amplifier includes operational amplifiers U2A, U2B and U3B, resistors R7, RG, R9-R13; The operational amplifiers U2A, U3B and resistors R7, RG, R9 constitute a preamplifier circuit; The operational amplifier U2B and R10-R13 constitute a differential amplifier circuit; Among them, operational amplifier U2A_2 is connected to capacitor C1_1, operational amplifier U2A_3 is connected to resistor R7_2, operational amplifier U2A_1 is connected to resistor R7_1, operational amplifier U3B_2 is connected to resistor R9_1, operational amplifier U3B_3 is connected to capacitor C2_2, operational amplifier U3B_1 is connected to resistor R9_2, resistor RG_1 is connected to resistor R7_2, resistor RG_2 is connected to resistor R9_1, resistor R12_1 is connected to resistor R7_1, resistor R10_1 is connected to resistor R9_2, operational amplifier U2B_2 is connected to resistor R12_2, operational amplifier U2B_3 is connected to resistor R10_2, resistor R13_1 is connected to resistor R12_2, resistor R11_1 is connected to resistor R10_2, resistor R11_2 is connected to GND, and resistor R13_2 is connected to operational amplifier U2B_1.

5. A high-precision three-dimensional alternating magnetic field detection method, based on the system of claim 4, characterized in that: The method includes: The original signal of the AC magnetic field is obtained by a three-dimensional coil and a SMD manganese copper resistor R3 arranged on the PCB board, wherein the three-dimensional coil includes a first coil, a second coil and a third coil arranged perpendicularly to each other, and both ends of the three-dimensional coil are connected to the SMD manganese copper resistor R3; Amplifying the original AC magnetic field signal to obtain an amplified AC magnetic field signal; Performing analog-to-digital conversion processing on the amplified AC magnetic field signal to convert the amplified AC magnetic field signal into a digital signal; determining the magnetic field strength and magnetic field direction of the AC magnetic field around the PCB board according to the corresponding relationship between the digital signal and the AC magnetic field strength; If the magnetic field strength exceeds a preset threshold, it is determined that electricity theft occurs around the smart meter.

6. The high-precision three-dimensional alternating current magnetic field detection method according to claim 5, characterized in that: The voltage across the chip manganese copper resistor R3 satisfies the following formula: VP-VN=(B×S / μ0N)×R3 Where: Φ is the magnetic flux, B is the magnetic field strength, S is the coil area, μ0 is the vacuum permeability, N is the number of coil turns, and I is the current in the coil.

7. The high-precision three-dimensional alternating current magnetic field detection method according to claim 6, characterized in that: The amplified AC magnetic field signal Vo satisfies the following formula: Vo=【R13×S×R3×(R7+R9+RG)×B】 / μ0N×RG×R12; Where: B is the magnetic field strength, S is the coil area, μ0 is the vacuum magnetic permeability, N is the number of coil turns, R3 is the resistance of the chip manganese copper resistor, R7, R9, RG, R12 and R13 are the resistance values ​​of the signal amplifier module resistors respectively.

8. The high-precision three-dimensional alternating current magnetic field detection method according to claim 5, characterized in that: The step of performing analog-to-digital conversion processing on the amplified alternating magnetic field signal comprises: The amplified AC magnetic field signal is quantized and encoded to obtain a digital quantized signal; The digital quantization signal is subjected to root mean square filtering, and a direct current component in the digital quantization signal is extracted as the digital signal.

9. The high-precision three-dimensional alternating current magnetic field detection method according to claim 5, characterized in that: Determining the magnetic field strength and magnetic field direction of the AC magnetic field around the PCB board according to the corresponding relationship between the digital signal and the AC magnetic field strength includes: Determine the component size of the AC magnetic field around the PCB board in the X-axis direction according to the digital signal obtained by the first coil; Determine the magnitude of the component of the alternating magnetic field around the PCB board in the Y-axis direction according to the digital signal acquired by the second coil; Determine the component size of the alternating magnetic field around the PCB board in the Z-axis direction according to the digital signal obtained by the third coil; The magnetic field intensity and magnetic field direction of the AC magnetic field around the PCB board are calculated according to the component in the X-axis direction, the component in the Y-axis direction, and the component in the Z-axis direction.

10. The high-precision three-dimensional alternating current magnetic field detection method according to claim 7, characterized in that: The corresponding relationship between the digital signal and the AC magnetic field strength satisfies the following formula: VD=【R13×S×R3×(R7+R9+RG)×B】×K / μ0N×RG×R12; Where: VD is the digital signal amplitude, K is the ADC conversion coefficient.

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