Power frequency magnetic field omnidirectional detection device and intelligent electric energy meter

Abstract

The invention provides a power frequency magnetic field omnidirectional detection device and an intelligent electric energy meter, and belongs to the field of electromagnetic detection. The device comprises an induction antenna, an amplitude limiting circuit and a peak holding circuit, the sensing antenna is used for sensing magnetic field signals around the intelligent electric energy meter to be detected and converting the magnetic field signals into alternating current signals; the amplitude limiting circuit is respectively connected with the induction antenna and the peak holding circuit; the amplitude limiting circuit is used for receiving the alternating current signal, clamping the alternating current signal and outputting a clamping signal; and the peak holding circuit is used for receiving the clamping signal, extracting a peak level signal of the clamping signal and continuously outputting the peak level signal so as to detect the magnetic field intensity around the intelligent electric energy meter to be detected based on the peak level signal. The electromagnetic pulse interference resistance of the power frequency magnetic field omnidirectional detection device can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic detection, and in particular to an omnidirectional power frequency magnetic field detection device and an intelligent electricity meter. Background Art

[0002] With the increasing complexity of the functions of intelligent electricity meters, the sensitivity of their internal electronic components to electromagnetic interference is also increasing. As a typical electromagnetic interference, the power frequency magnetic field may generate additional currents inside the electricity meter through electromagnetic induction, and these induced currents may interfere with the normal operation of the electricity meter, resulting in measurement errors. Therefore, studying the power frequency magnetic field detection technology for intelligent electricity meters is of great significance for ensuring the accuracy of power measurement and the reliability of electricity meters.

[0003] Currently, there are mainly two omnidirectional power frequency magnetic field detection technologies: magnetoresistive sensor technology and Hall sensor technology. A magnetoresistive sensor consists of a magnetoresistive element and a signal processing circuit. Under the action of an external magnetic field, the electron magnetic moments in the magnetoresistive sensor are reorganized, causing a change in resistance, which is then converted into a voltage signal to achieve magnetic field detection. The Hall sensor solution consists of a Hall element, an amplifier, and a voltage stabilizing circuit. The magnetic field generates a Hall electromotive force, which is amplified and then outputs a voltage or frequency pulse signal proportional to the magnetic field strength to achieve magnetic field detection.

[0004] In related technologies, these sensors are usually integrated on a single chip to improve the reliability and performance of the product. However, as the size of the integrated chip decreases, the damage effect of electromagnetic pulses on the integrated chip becomes more significant. On the one hand, electromagnetic pulses may enter the integrated circuit through metal interconnects or aperture coupling, causing internal damage to the chip; on the other hand, electromagnetic pulses may cause changes in the electrothermal field inside the chip, leading to the latch-up effect of internal digital devices, resulting in chip damage or burnout. In summary, the existing omnidirectional power frequency magnetic field detection devices have weak anti-electromagnetic pulse interference capabilities. Summary of the Invention

[0005] Embodiments of the present invention provide an omnidirectional power frequency magnetic field detection device and an intelligent electricity meter to improve the anti-electromagnetic pulse interference ability of the omnidirectional power frequency magnetic field detection device.

[0006] In a first aspect, embodiments of the present invention provide an omnidirectional power frequency magnetic field detection device, which is disposed inside a to-be-tested intelligent electricity meter. The device includes: an induction antenna, a limiting circuit, and a peak holding circuit;

[0007] The induction antenna is configured to sense the magnetic field signals around the to-be-tested intelligent electricity meter and convert the magnetic field signals into alternating current signals;

[0008] The limiting circuit is respectively connected to the induction antenna and the peak holding circuit;

[0009] The clamping circuit is used to receive the alternating current signal, clamp the alternating current signal, and output a clamped signal;

[0010] The peak holding circuit is used to receive the clamped signal, extract the peak level signal of the clamped signal, and continuously output the peak level signal, so as to detect the magnetic field intensity around the intelligent electricity meter to be measured based on the peak level signal.

[0011] In a possible implementation manner, the clamping circuit includes: a first diode and a second diode;

[0012] The negative electrode of the first diode is respectively connected to the induction antenna and the signal input end of the peak holding circuit;

[0013] The positive electrode of the first diode is grounded;

[0014] The positive electrode of the second diode is connected to the negative electrode of the first diode, and the negative electrode of the second diode is connected to the positive electrode of the first diode.

[0015] In a possible implementation manner, the peak holding circuit includes: a first resistor, a first operational amplifier, a second resistor, a third resistor, a third diode, a fourth diode, a capacitor and a fourth resistor;

[0016] One end of the first resistor serves as the signal input end of the peak holding circuit, is connected to the clamping circuit, and the other end of the first resistor is connected to the first signal input end of the first operational amplifier;

[0017] One end of the second resistor is grounded, and the other end of the second resistor is connected to the second signal input end of the first operational amplifier;

[0018] The second signal input end of the first operational amplifier is also respectively connected to the positive electrode of the third diode and one end of the third resistor;

[0019] The negative electrode of the third diode is respectively connected to the signal output end of the first operational amplifier and the positive electrode of the fourth diode;

[0020] The negative electrode of the fourth diode is respectively connected to one end of the capacitor and one end of the fourth resistor;

[0021] The other end of the capacitor and the other end of the fourth resistor are both grounded;

[0022] The negative electrode of the fourth diode serves as the signal output end of the peak holding circuit for outputting the peak level signal;

[0023] The other end of the third resistor is connected to the signal output end of the peak holding circuit.

[0024] In a possible implementation, the peak holding circuit further includes: a second operational amplifier;

[0025] The first signal input terminal of the second operational amplifier is connected to the negative electrode of the fourth diode;

[0026] The second signal input terminal of the second operational amplifier is connected to the signal output terminal of the second operational amplifier;

[0027] The signal output terminal of the second operational amplifier serves as the signal output terminal of the peak holding circuit, and is used to output the peak level signal processed by the second operational amplifier, so as to detect the magnetic field intensity around the smart electricity meter to be measured based on the peak level signal processed by the second operational amplifier.

[0028] In a possible implementation, the voltage value of the positive power supply terminal of the first operational amplifier is greater than 0V and less than or equal to +15V, and the voltage value of the negative power supply terminal of the first operational amplifier is greater than or equal to -15V and less than 0V.

[0029] In a possible implementation, the limiting circuit and the peak holding circuit are arranged in a shielding case.

[0030] In a possible implementation, the material of the shielding case is cupronickel, tinplate or zinc tin nickel alloy.

[0031] In a possible implementation, the induction antenna is a 3D low-frequency induction antenna, and the 3D low-frequency induction antenna includes 3 closed coils. The center points of the closed coils coincide, and the planes where the closed coils are located respectively correspond to the three orthogonal planes X, Y, and Z in the three-dimensional XYZ coordinate system; the three-dimensional XYZ coordinate system takes the center point as the coordinate origin.

[0032] In a possible implementation, the voltage amplitude of the clamping signal is greater than or equal to 0V and less than or equal to 1V.

[0033] In a second aspect, an embodiment of the present invention provides a smart electricity meter, including: the power frequency magnetic field omnidirectional detection device according to any item in the first aspect above.

[0034] An embodiment of the present invention provides an omnidirectional detection device for power frequency magnetic fields and an intelligent electricity meter. By using an induction antenna to sense the magnetic field signals around the intelligent electricity meter to be measured and converting the magnetic field signals into alternating current signals, then, using a limiting circuit and a peak holding circuit to clamp the alternating current signals and convert them into peak level signals, so that the magnetic field intensity around the intelligent electricity meter to be measured can be detected based on the peak level signals. Compared with electromagnetic sensing chips such as magnetoresistive sensors and Hall sensors, in the embodiment of the present invention, an induction antenna is used for electromagnetic induction, and its anti-electromagnetic pulse interference ability is stronger, and the influence of electromagnetic pulse interference on the alternating current signals can be avoided as much as possible. On this basis, the limiting circuit clamps the alternating current signals, which can effectively contain the instantaneous electromagnetic pulse interference that is not resisted by the induction coil, and further improves the anti-electromagnetic pulse interference ability of the omnidirectional detection device for power frequency magnetic fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0036] Figure 1 FIG. is a schematic structural diagram of an omnidirectional detection device for power frequency magnetic fields provided by an embodiment of the present invention;

[0037] Figure 2 FIG. is a schematic structural diagram of an induction antenna provided by an embodiment of the present invention;

[0038] Figure 3 FIG. is a schematic structural diagram of a limiting circuit and a peak holding circuit provided by an embodiment of the present invention;

[0039] Figure 4 FIG. is a schematic structural diagram of a limiting circuit and a peak holding circuit provided by another embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] In the following description, specific details such as specific system structures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present invention. However, those skilled in the art should clearly understand that the present invention can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present invention.

[0041] In the related art, when performing omnidirectional detection of power frequency magnetic fields, magnetoresistive sensors or Hall sensors are usually integrated on a chip to realize magnetic field detection and improve product reliability and performance. However, as the size of integrated chips decreases, the damaging effect of electromagnetic pulses on integrated chips becomes more significant. On the one hand, electromagnetic pulses may couple into the interior of the integrated circuit through metal interconnects or apertures, causing damage to the chip; on the other hand, electromagnetic pulses may cause changes in the electric and thermal fields inside the chip, leading to a latch effect of internal digital devices, causing damage or burning of the chip. In summary, the existing power frequency magnetic field omnidirectional detection devices have the problem of weak resistance to electromagnetic pulse interference.

[0042] In order to improve the anti-electromagnetic pulse interference capability of the omnidirectional detection device of the power frequency magnetic field, in the embodiment of the present invention, an induction antenna is used for electromagnetic induction to obtain an AC signal, and a limiting circuit and a peak holding circuit are used to clamp the AC signal and convert it into a peak level signal, thereby realizing magnetic field detection. Compared with electromagnetic sensor chips such as magnetoresistive sensors and Hall sensors, the induction antenna used for electromagnetic induction in the embodiment of the present invention has a stronger anti-electromagnetic pulse interference capability, and can avoid the AC signal from being affected by electromagnetic pulse interference as much as possible. On this basis, the limiting circuit clamps the AC signal, which can effectively curb the instantaneous electromagnetic pulse interference that is not resisted by the induction coil, and further improve the anti-electromagnetic pulse interference capability of the omnidirectional detection device of the power frequency magnetic field.

[0043] In order to make the purpose, technical solutions and advantages of the present invention more clear, specific embodiments will be described below in conjunction with the accompanying drawings.

[0044] Figure 1 The schematic diagram of the structure of the omnidirectional detection device of the power frequency magnetic field provided by the embodiment of the present invention. Figure 1 As shown, the power frequency magnetic field omnidirectional detection device may include: an induction antenna 11, a limiter circuit 12 and a peak holding circuit 13;

[0045] The sensing antenna 11 is used to sense the magnetic field signal around the smart electric energy meter to be tested and convert the magnetic field signal into an alternating current signal;

[0046] The amplitude limiting circuit 12 is respectively connected to the sensing antenna 11 and the peak holding circuit 13;

[0047] The limiting circuit 12 is used to receive an AC signal, clamp the AC signal, and output a clamped signal;

[0048] The peak holding circuit 13 is used to receive the clamp signal, extract the peak level signal of the clamp signal, and continuously output the peak level signal, so as to detect the magnetic field strength around the smart electric energy meter to be tested based on the peak level signal.

[0049] According to Faraday's law of induction, when the magnetic field around a coil changes, an induced electromotive force will be generated in the coil. The calculation formula for the induced electromotive force is as follows:

[0050] ε = -N × A × cosθ × (dB / dt)

[0051] Among them, ε is the induced electromotive force, N is the number of turns of the coil, A is the effective area of the coil, θ is the angle between the magnetic field and the coil, and dB / dt is the rate of change of magnetic flux density.

[0052] As can be seen from the above formula, when the number of turns, effective area, and the angle with the magnetic field of the coil are fixed, the only factor affecting the magnitude of its induced electromotive force is the rate of change of magnetic flux density. Therefore, the magnetic induction intensity of the magnetic field can be measured by measuring the magnitude of the induced electromotive force.

[0053] According to the above Faraday induction principle, the embodiment of the present invention constructs an omnidirectional detection device for power frequency magnetic fields based on an induction antenna, a limiting circuit, and a peak induction circuit. This omnidirectional detection device for power frequency magnetic fields can be arranged inside the smart electricity meter to be measured, and is used to detect the power frequency magnetic field intensity around the smart electricity meter to be measured.

[0054] Among them, the induction antenna in the omnidirectional detection device for power frequency magnetic fields can convert the power frequency magnetic field signal around the smart electricity meter to be measured into an alternating current signal. The limiting circuit can clamp the alternating current signal and output a clamped signal. The peak holding circuit is used to extract the peak level signal of the clamped signal and continuously output the peak level signal. This peak level signal can reflect the power frequency magnetic field intensity around the smart electricity meter to be measured. The embodiment of the present invention can detect the power frequency magnetic field intensity around the smart electricity meter to be measured based on this peak level signal.

[0055] In the embodiment of the present invention, when detecting the power frequency magnetic field intensity around the smart electricity meter to be measured, the peak level signal can be compared with a preset level signal. When the amplitude of the peak level signal is greater than or equal to the amplitude of the preset level signal, it is determined that the magnetic field intensity around the smart electricity meter to be measured exceeds the set magnetic field intensity, so as to ensure the metering accuracy of the smart electricity meter to be measured.

[0056] Here, the set magnetic field intensity can be a magnetic field intensity that does not affect the metering accuracy of the smart electricity meter to be measured. The preset level signal can be determined according to the induced electromotive force corresponding to the set magnetic field intensity.

[0057] In some embodiments, the induction antenna is a 3D low-frequency induction antenna. The 3D low-frequency induction antenna includes 3 closed coils. The center points of the closed coils coincide, and the planes where the closed coils are located respectively correspond to the three orthogonal planes XYZ in the three-dimensional XYZ coordinate system; the three-dimensional XYZ coordinate system takes the center point as the coordinate origin.

[0058] Such asFigure 2 As shown in the figure, the 3D low-frequency induction antenna is composed of three combined closed coils. Each coil plane is formed by a closed conductive coil, and the three coils are respectively located on three orthogonal planes of X, Y, and Z. Through the combination of the three orthogonal coils, the components of the magnetic field in three spatial dimensions can be measured, thereby realizing the omnidirectional detection of the magnetic field.

[0059] Compared with the integrated magnetic field detection chip, the 3D low-frequency induction antenna has stronger anti-pulse interference ability. However, it may still generate instantaneous impact voltage under the interference of external high-voltage pulses, affecting the backend circuit. To eliminate the induced electromotive force and further improve its anti-pulse interference ability, in the embodiment of the present invention, a limiting circuit is added to the signal output end of the induction antenna to clamp the alternating current signal output by the induction antenna, so as to further contain the instantaneous electromagnetic interference pulse.

[0060] Compared with the prior art, in the embodiment of the present invention, the magnetic field signal around the intelligent electricity meter to be measured is induced by the induction antenna and converted into an alternating current signal. Then, the limiting circuit and the peak holding circuit are used to clamp the alternating current signal and convert it into a peak level signal, so that the magnetic field intensity around the intelligent electricity meter to be measured can be detected based on the peak level signal. Compared with electromagnetic sensing chips such as magnetoresistive sensors and Hall sensors, the induction antenna is used for electromagnetic induction in the embodiment of the present invention, and it has stronger anti-electromagnetic pulse interference ability, and can avoid the influence of the alternating current signal being affected by electromagnetic pulse interference as much as possible. On this basis, the limiting circuit clamps the alternating current signal, which can effectively contain the instantaneous electromagnetic pulse interference that is not resisted by the induction coil, and further improves the anti-electromagnetic pulse interference ability of the power frequency magnetic field omnidirectional detection device.

[0061] In some embodiments, referring to Figure 3 , the limiting circuit 12 includes: a first diode D1 and a second diode D2;

[0062] The negative electrode of the first diode D1 is respectively connected to the induction antenna 11 and the signal input end of the peak holding circuit 13;

[0063] The positive electrode of the first diode D1 is grounded;

[0064] The positive electrode of the second diode D2 is connected to the negative electrode of the first diode D1, and the negative electrode of the second diode D2 is connected to the positive electrode of the first diode D1.

[0065] In the embodiment of the present invention, the first diode D1 and the second diode D2 connected in reverse parallel can clamp the alternating current signal generated by electromagnetic induction, thereby limiting the voltage amplitude of the clamped signal after clamping, so as to avoid the influence of instantaneous electromagnetic pulse interference on the backend circuit.

[0066] In some embodiments, the voltage amplitude of the clamping signal is greater than or equal to 0V and less than or equal to 1V. Usually, the first diode and the second diode can clamp the voltage amplitude of the clamping signal at 0.7V.

[0067] Based on the clamping signal, the embodiment of the present invention further converts the clamping signal into a peak level signal, thereby converting the alternating current signal into a digital level signal, so that the MCU disposed inside the smart electricity meter to be measured can perform data processing and analysis based on the digital level signal, thereby detecting the magnetic field intensity around the smart electricity meter to be measured.

[0068] In some embodiments, referring to Figure 3 , the peak holding circuit 13 includes: a first resistor R1, a first operational amplifier Q1, a second resistor R2, a third resistor R3, a third diode D3, a fourth diode D4, a capacitor C, and a fourth resistor R4;

[0069] One end of the first resistor R1 serves as the signal input end of the peak holding circuit 13 and is connected to the limiting circuit 12, and the other end of the first resistor R1 is connected to the first signal input end of the first operational amplifier Q1;

[0070] One end of the second resistor R2 is grounded, and the other end of the second resistor R2 is connected to the second signal input end of the first operational amplifier Q1;

[0071] The second signal input end of the first operational amplifier Q1 is also respectively connected to the positive electrode of the third diode D3 and one end of the third resistor R3;

[0072] The negative electrode of the third diode D3 is respectively connected to the signal output end of the first operational amplifier Q1 and the positive electrode of the fourth diode D4;

[0073] The negative electrode of the fourth diode D4 is respectively connected to one end of the capacitor C and one end of the fourth resistor R4;

[0074] The other end of the capacitor C and the other end of the fourth resistor R4 are both grounded;

[0075] The negative electrode of the fourth diode D4 serves as the signal output end of the peak holding circuit 13 for outputting a peak level signal;

[0076] The other end of the third resistor R3 is connected to the signal output end of the peak holding circuit 13.

[0077] It can be understood that the clamping signal is a sinusoidal alternating current signal. The peak holding circuit 13 can store the peak value of the sinusoidal alternating current signal and output it in the form of a direct current signal.

[0078] Here, the first operational amplifier can be regarded as a voltage comparator. When the input voltage of the voltage comparator gradually increases, the voltage comparator outputs the positive voltage value of the positive power supply terminal, and the capacitor C starts to charge. Here, the charging voltage of the capacitor is the output voltage of the voltage comparator. When the charging voltage is greater than the input voltage, the voltage comparator outputs the negative voltage value of the negative power supply terminal, and the fourth diode D4 is turned off, and the capacitor C discharges. When the capacitor C discharges to less than the input voltage, the fourth diode D4 conducts again. In this way, the capacitor C is always in a charge-discharge cycle state, so that the peak holding circuit always outputs a peak level signal.

[0079] In some embodiments, the voltage value of the positive power supply terminal of the first operational amplifier is greater than 0V and less than or equal to +15V, and the voltage value of the negative power supply terminal of the first operational amplifier is greater than or equal to -15V and less than 0V.

[0080] Exemplarily, in the embodiment of the present invention, the voltage value of the positive power supply terminal of the first operational amplifier is +5V, and the voltage value of the negative power supply terminal of the first operational amplifier is -5V.

[0081] In some embodiments, referring to Figure 4 , the peak holding circuit further includes: a second operational amplifier Q2;

[0082] The first signal input terminal of the second operational amplifier is connected to the negative electrode of the fourth diode;

[0083] The second signal input terminal of the second operational amplifier is connected to the signal output terminal of the second operational amplifier;

[0084] The signal output terminal of the second operational amplifier is used as the signal output terminal of the peak holding circuit, and is used to output the peak level signal processed by the second operational amplifier, so as to detect the magnetic field intensity around the intelligent electricity meter to be measured based on the peak level signal processed by the second operational amplifier.

[0085] Referring to Figure 4 , it should be noted that when the second operational amplifier is provided in the peak holding circuit, the signal output terminal of the second operational amplifier is used as the signal output terminal of the peak holding circuit. At this time, different from the embodiment in Figure 3 , the other end of the third resistor R3 is connected to the signal output terminal of the second operational amplifier.

[0086] Here, the second operational amplifier can be a voltage follower, which can play a role in isolating the front-end and back-end circuits, and can further reduce the noise interference in the peak level signal.

[0087] Exemplarily, in the embodiment of the present invention, the voltage value of the positive power supply terminal of the second operational amplifier is +5V, and the voltage value of the negative power supply terminal of the second operational amplifier is -5V.

[0088] In some embodiments, the limiting circuit and the peak holding circuit are disposed within a shielding case.

[0089] In some embodiments, the material of the shielding case is cupronickel, tinplate or zinc tin nickel alloy.

[0090] The shielding case shields the limiting circuit and the peak holding circuit to prevent the integrated chips in the circuit from being damaged by strong electromagnetic pulses, and further improves the anti-pulse interference ability of the power frequency magnetic field omnidirectional detection device.

[0091] The embodiment of the present invention combines a low-cost surface-mounted 3D low-frequency induction antenna with a limiting circuit and a peak holding circuit to realize a comprehensive measurement of the three-dimensional magnetic field around the smart electricity meter. On this basis, the embodiment of the present invention improves the anti-pulse interference ability of the power frequency magnetic field omnidirectional detection device through optimization measures such as physical shielding and limiting circuits.

[0092] Based on the above power frequency magnetic field omnidirectional detection device, the embodiment of the present invention further provides a smart electricity meter, including: the above power frequency magnetic field omnidirectional detection device.

[0093] The above-described embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A power frequency magnetic field omnidirectional detection device, characterized in that: The device is arranged inside the smart electric energy meter to be tested, and comprises: an induction antenna, a limiting circuit and a peak holding circuit; The sensing antenna is used to sense the magnetic field signal around the smart electric energy meter to be tested and convert the magnetic field signal into an alternating current signal; The amplitude limiting circuit is respectively connected to the sensing antenna and the peak holding circuit; The limiting circuit is used to receive the AC signal, clamp the AC signal, and output a clamping signal; The peak holding circuit is used to receive the clamp signal, extract the peak level signal of the clamp signal, and continuously output the peak level signal, so as to detect the magnetic field strength around the smart electric energy meter to be tested based on the peak level signal.

2. The power frequency magnetic field omnidirectional detection device according to claim 1, characterized in that: The amplitude limiting circuit comprises: a first diode and a second diode; The cathode of the first diode is respectively connected to the sensing antenna and the signal input end of the peak holding circuit; The anode of the first diode is grounded; The anode of the second diode is connected to the cathode of the first diode, and the cathode of the second diode is connected to the anode of the first diode.

3. The power frequency magnetic field omnidirectional detection device according to claim 1 or 2, characterized in that: The peak holding circuit comprises: a first resistor, a first operational amplifier, a second resistor, a third resistor, a third diode, a fourth diode, a capacitor and a fourth resistor; One end of the first resistor is used as a signal input end of the peak holding circuit and is connected to the amplitude limiting circuit, and the other end of the first resistor is connected to a first signal input end of the first operational amplifier; One end of the second resistor is grounded, and the other end of the second resistor is connected to the second signal input end of the first operational amplifier; The second signal input terminal of the first operational amplifier is also connected to the anode of the third diode and one end of the third resistor respectively; The cathode of the third diode is respectively connected to the signal output terminal of the first operational amplifier and the anode of the fourth diode; The cathode of the fourth diode is connected to one end of the capacitor and one end of the fourth resistor respectively; The other end of the capacitor and the other end of the fourth resistor are both grounded; The cathode of the fourth diode serves as a signal output terminal of the peak holding circuit, and is used to output the peak level signal; The other end of the third resistor is connected to the signal output end of the peak holding circuit.

4. The power frequency magnetic field omnidirectional detection device according to claim 3, characterized in that: The peak hold circuit further includes: a second operational amplifier; The first signal input terminal of the second operational amplifier is connected to the cathode of the fourth diode; The second signal input terminal of the second operational amplifier is connected to the signal output terminal of the second operational amplifier; The signal output end of the second operational amplifier serves as the signal output end of the peak holding circuit, and is used to output the peak level signal processed by the second operational amplifier, so as to detect the magnetic field strength around the smart electric energy meter to be tested based on the peak level signal processed by the second operational amplifier.

5. The power frequency magnetic field omnidirectional detection device according to claim 3, characterized in that: The voltage value of the positive power supply terminal of the first operational amplifier is greater than 0V and less than or equal to +15V, and the voltage value of the negative power supply terminal of the first operational amplifier is greater than or equal to -15V and less than 0V.

6. The power frequency magnetic field omnidirectional detection device according to claim 1 or 2, characterized in that: The amplitude limiting circuit and the peak holding circuit are arranged in a shielding case.

7. The power frequency magnetic field omnidirectional detection device according to claim 6, characterized in that: The shielding cover is made of nickel silver, tinplate or zinc-tin-nickel alloy.

8. The power frequency magnetic field omnidirectional detection device according to claim 1 or 2, characterized in that: The sensing antenna is a 3D low-frequency sensing antenna, which includes three closed coils, the center points of the closed coils coincide, and the planes where the closed coils are located correspond to three orthogonal planes XYZ in a three-dimensional XYZ coordinate system; the three-dimensional XYZ coordinate system uses the center point as the coordinate origin.

9. The power frequency magnetic field omnidirectional detection device according to claim 1 or 2, characterized in that: The voltage amplitude of the clamp signal is greater than or equal to 0V and less than or equal to 1V.

10. A smart electric energy meter, characterized in that: include: The omnidirectional detection device for industrial frequency magnetic field as described in any one of claims 1 to 9.

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