Micro-current sensing circuit and micro-current sensing system

Abstract

The invention relates to a micro-current sensing circuit and a micro-current sensing system, the micro-current sensing circuit comprises a direct current detection path and an alternating current detection path which are arranged in parallel, and the direct current detection path can detect a to-be-detected current based on direct current magnetic flux compensation to obtain a direct current analog signal; the AC detection path can detect a to-be-detected current based on AC magnetic flux compensation to obtain an AC analog signal. The micro-current sensing circuit reaches a zero magnetic flux state under the action of direct-current magnetic flux compensation and alternating-current magnetic flux compensation. The direct current detection path and the alternating current detection path are respectively arranged, so that detection of direct current and alternating current micro current is more specialized and accurate. And a zero magnetic flux state is achieved under the action of direct-current magnetic flux compensation and alternating-current magnetic flux compensation, so that the influence of an external interference magnetic field on measurement is greatly reduced. And the detection of direct current and alternating current can be carried out in an environment with almost no interference, so that the measurement precision is remarkably improved.

Description

Technical Field

[0001] The present application relates to the field of microcurrent detection technology, and in particular to a microcurrent sensing circuit and a microcurrent sensing system. Background Art

[0002] With the large-scale grid connection of new energy distributed power sources, the high proportion of new energy access will lead to strong uncertainty and volatility, and serious distortion of current waveform, which will impact traditional electric energy metering equipment, resulting in large measurement errors in the use of the original electric energy metering equipment. The flux circuit can cope with this complex current environment.

[0003] However, the traditional zero-flux sensing circuit can only measure DC current, which has great limitations. Summary of the invention

[0004] Based on this, it is necessary to provide a microcurrent sensing circuit and a microcurrent sensing system that can solve the above-mentioned technical problems.

[0005] In a first aspect, the present application provides a micro-current sensing circuit, the micro-current sensing circuit comprising a DC detection path and an AC detection path arranged in parallel;

[0006] A DC detection path, used for detecting the current to be measured based on DC flux compensation to obtain a DC analog signal;

[0007] An AC detection path, used for detecting the current to be measured based on AC flux compensation to obtain an AC analog signal;

[0008] Among them, the micro-current sensing circuit reaches a zero flux state under the action of DC flux compensation and AC flux compensation.

[0009] In one embodiment, the DC detection path includes a DC fluxgate circuit, a DC signal adjustment circuit, a DC feedback circuit and a DC output circuit; the DC fluxgate circuit is connected to the DC output circuit through the DC signal adjustment circuit; the DC feedback circuit is connected to the DC signal adjustment circuit and the DC fluxgate circuit respectively;

[0010] A DC fluxgate circuit is used to generate a DC induction signal according to the current to be measured, and to make the micro-current sensing circuit reach a zero flux state under the action of DC flux compensation and AC flux compensation;

[0011] A DC signal adjustment circuit is used to perform DC signal adjustment processing on the DC sensing signal to obtain an adjusted DC sensing signal;

[0012] A DC feedback circuit is used to generate a DC compensation circuit according to the adjusted induction signal to perform DC magnetic flux compensation;

[0013] The DC output circuit is used to output a DC analog signal outputted from the secondary side based on the adjusted DC sensing signal.

[0014] In one embodiment, the AC detection path includes an AC fluxgate circuit, an AC signal adjustment circuit, an AC feedback circuit and an AC output circuit; the AC fluxgate circuit is connected to the AC output circuit through the AC signal adjustment circuit; the AC feedback circuit is connected to the AC signal adjustment circuit and the AC fluxgate circuit respectively;

[0015] An AC fluxgate circuit is used to generate an AC induction signal according to the current to be measured, and to make the micro-current sensing circuit reach a zero flux state under the action of DC flux compensation and AC flux compensation;

[0016] The AC signal adjustment circuit is used to perform AC signal adjustment processing on the AC induction signal to obtain an adjusted AC induction signal;

[0017] An AC feedback circuit is used to generate an AC compensation current according to the adjusted induction signal to perform AC magnetic flux compensation;

[0018] The AC output circuit is used to output an AC analog signal outputted from the secondary side based on the adjusted AC induction signal.

[0019] In one embodiment, the DC signal adjustment circuit includes a DC resonant frequency selection circuit, a DC differential amplifier circuit, a DC analog-to-digital conversion circuit and a DC digital signal processing circuit connected in sequence; the DC resonant frequency selection circuit is connected to the DC fluxgate circuit; the DC digital signal processing circuit is respectively connected to the DC feedback circuit and the DC output circuit;

[0020] A DC resonant frequency selection circuit is used to perform DC signal frequency selection processing on a DC induction signal to obtain a DC frequency signal;

[0021] A DC differential amplifier circuit is used to perform DC signal differential amplification processing on a DC frequency signal to obtain a DC differential amplified signal;

[0022] A DC analog-to-digital conversion circuit is used to perform DC analog-to-digital conversion processing on the DC differential amplification signal to obtain a DC analog-to-digital conversion signal;

[0023] The DC digital signal processing circuit is used for performing DC digital signal processing on the DC analog-to-digital conversion signal to obtain an adjusted DC sensing signal.

[0024] In one embodiment, the AC signal adjustment circuit includes an AC resonant frequency selection circuit, an AC differential amplifier circuit, an AC analog-to-digital conversion circuit, and an AC digital signal processing circuit connected in sequence; the AC resonant frequency selection circuit is connected to the AC fluxgate circuit; the AC digital signal processing circuit is respectively connected to the AC feedback circuit and the AC output circuit;

[0025] The AC resonant frequency selection circuit is used to perform AC signal frequency selection processing on the AC induction signal to obtain an AC frequency signal;

[0026] The AC differential amplifier circuit is used to perform AC signal differential amplification processing on the AC frequency signal to obtain an AC differential amplified signal;

[0027] The AC analog-to-digital conversion circuit is used to perform an AC analog-to-digital conversion process on the AC differential amplified signal to obtain an AC analog-to-digital conversion signal;

[0028] The AC digital signal processing circuit is used to perform AC digital signal processing on the AC analog-to-digital conversion signal to obtain an adjusted AC induction signal.

[0029] In one embodiment, the AC fluxgate circuit includes a first magnetic core circuit and a second magnetic core circuit; the first magnetic core circuit includes a first excitation coil, a first induction coil and a first magnetic core; the second magnetic core circuit includes a second excitation coil, a second induction coil, a feedback coil and a second magnetic core; the first excitation coil and the first induction coil are wound on the first magnetic core; the second excitation coil, the second induction coil and the feedback coil are wound on the second magnetic core; the first excitation coil is connected to the second excitation coil; the first excitation coil is also used to connect to an excitation source circuit outside the micro-current sensor circuit; the first induction coil is connected to a signal adjustment circuit through the second induction coil; the feedback coil is connected to the feedback circuit;

[0030] A first excitation coil, used to generate a first alternating magnetic field according to the current to be measured;

[0031] A first induction coil, used to detect a magnetic field change of the first alternating magnetic field and generate a first alternating induction current;

[0032] A second excitation coil, used to generate a second alternating magnetic field according to the current to be measured;

[0033] a second induction coil, used to detect a magnetic field change of a second alternating magnetic field and generate a second alternating induction current;

[0034] The feedback coil is used to generate a compensation magnetic field according to the AC compensation current.

[0035] In one embodiment, the AC feedback circuit includes an AC digital-to-analog conversion circuit, an AC control voltage generation circuit, and an AC voltage-controlled current source circuit connected in sequence; the AC digital-to-analog conversion circuit is connected to the AC signal adjustment circuit; the AC voltage-controlled current source circuit is connected to the AC fluxgate circuit;

[0036] The AC digital-to-analog conversion circuit is used to perform AC digital-to-analog conversion processing on the adjusted AC induction signal to obtain an AC feedback signal;

[0037] The AC control voltage generating circuit is used to convert the AC feedback signal into an AC voltage to obtain an AC control voltage;

[0038] The AC voltage-controlled current source circuit is used to perform AC voltage-current conversion processing on the AC control voltage to obtain the AC compensation current.

[0039] In one embodiment, the AC output circuit comprises an AC amplifying circuit and an AC analog output circuit connected in sequence; the AC amplifying circuit is connected to the AC signal adjusting circuit;

[0040] The AC amplifier circuit is used to amplify the AC current signal on the secondary side to obtain an amplified AC current signal;

[0041] The AC analog output circuit is used to perform AC signal conversion processing on the amplified AC current signal to obtain an AC analog signal.

[0042] In one embodiment, the AC fluxgate circuit has the same structure as the DC fluxgate circuit; the AC feedback circuit has the same structure as the DC feedback circuit; and the AC output circuit has the same structure as the DC output circuit.

[0043] In a second aspect, the present application further provides a microcurrent sensing system, which includes an excitation source circuit and the microcurrent sensing circuit of the first aspect above; the excitation source circuit is connected to the microcurrent sensing circuit; the microcurrent sensing circuit includes a DC detection path and an AC detection path arranged in parallel;

[0044] An excitation source circuit, used for generating a current to be measured;

[0045] A DC detection path, used for detecting the current to be measured based on DC flux compensation to obtain a DC analog signal;

[0046] An AC detection path, used for detecting the current to be measured based on AC flux compensation to obtain an AC analog signal;

[0047] Among them, the micro-current sensing circuit reaches a zero flux state under the action of DC flux compensation and AC flux compensation.

[0048] In one embodiment, the micro-current sensing system further includes a temperature acquisition circuit; the temperature acquisition circuit is connected to the micro-current sensing circuit;

[0049] The temperature acquisition circuit is used to detect the ambient temperature and, when the ambient temperature meets the preset temperature, correct the DC analog signal and the AC analog signal to obtain the corrected DC analog signal and the AC analog signal.

[0050] The above-mentioned microcurrent sensing circuit includes a DC detection path and an AC detection path arranged in parallel. The DC detection path can detect the current to be measured based on DC flux compensation to obtain a DC analog signal; the AC detection path can detect the current to be measured based on AC flux compensation to obtain an AC analog signal. The microcurrent sensing circuit reaches a zero flux state under the action of DC flux compensation and AC flux compensation. The present application sets up a DC detection path and an AC detection path respectively, so that the detection of DC and AC microcurrents is more professional and precise. The zero flux state is reached under the action of DC flux compensation and AC flux compensation, which greatly reduces the influence of external interference magnetic fields on the measurement. Whether it is the detection of DC or AC current, it can be carried out in an almost interference-free environment, thereby significantly improving the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a schematic diagram of a micro-current sensing circuit in one embodiment;

[0052] Figure 2 is a schematic diagram of a DC detection path in one embodiment;

[0053] Figure 3 is a schematic diagram of an AC detection path in one embodiment;

[0054] Figure 4 is a schematic diagram of a DC signal adjustment circuit in one embodiment;

[0055] Figure 5 is a schematic diagram of an AC signal adjustment circuit in one embodiment;

[0056] Figure 6 is a schematic structural diagram of an AC fluxgate circuit in one embodiment;

[0057] Figure 7 is a schematic diagram of an AC feedback circuit in one embodiment;

[0058] Figure 8 is a schematic diagram of an AC output circuit in one embodiment;

[0059] Fig. 9 is a schematic diagram of a micro-current sensing system in one embodiment;

[0060] Fig.10 is a schematic diagram of a temperature acquisition circuit in one embodiment;

[0061] Fig.11 Detailed schematic diagram of a micro-current sensing circuit in one embodiment. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0063] First of all, before specifically introducing the technical solution of the embodiments of the present application, the technical background based on the embodiments of the present application is introduced.

[0064] With the large-scale grid connection of new energy distributed power sources, the high proportion of new energy access has strong uncertainty and volatility, and the current waveform is seriously distorted, which will impact traditional electricity metering equipment and cause large measurement errors in the use of the original electricity metering equipment.

[0065] The traditional fluxgate current sensing circuit adopts an open-loop structure, and the magnetic core is made of hard magnetic material. The linearity of the sensing circuit is low, and the measurement range and stability are low. Ordinary zero flux sensing circuits can only measure DC current, and are not suitable for special high temperature scenarios and have poor high temperature resistance.

[0066] The existing high-temperature fluxgate sensing circuit has technical difficulties such as high-temperature device performance loss, difficulty in modulating the magnetic core permeability, and limited circuit size and selection. At the same time, the existing fluxgate current sensing circuit can only detect DC current, but cannot detect high-frequency ripple components and AC current. The sensing circuit has low accuracy, and its open-loop magnetic field structure and the structure of hard magnetic material as the iron core result in low measurement range, measurement stability and measurement linearity.

[0067] Based on this, the present application provides a microcurrent sensing circuit and a microcurrent sensing system, aiming to solve the above technical problems.

[0068] In one embodiment, the present application provides a micro-current sensing circuit 01, see Figure 1 The micro-current sensing circuit includes a DC detection path 10 and an AC detection path 11 which are arranged in parallel.

[0069] The DC detection path 10 is used to detect the current to be measured based on DC flux compensation to obtain a DC analog signal.

[0070] An AC detection path 11 is used to detect the current to be measured based on AC flux compensation to obtain an AC analog signal;

[0071] Wherein, the micro-current sensing circuit 01 reaches a zero flux state under the effects of DC flux compensation and AC flux compensation.

[0072] The zero flux state means that under the joint action of DC flux compensation and AC flux compensation, the influence of the external magnetic field on the micro-current sensing circuit is minimized, approaching the ideal state of no flux, thereby improving the measurement accuracy and stability.

[0073] In the embodiment of the present application, the DC detection path 10 may mainly include a DC sensor, a DC amplifier, a DC magnetic flux compensation circuit and other parts.

[0074] When the current to be measured passes through the DC sensor, a magnetic field is generated around the sensor. The DC flux compensation circuit generates a compensation magnetic field opposite to the magnetic field generated by the current to be measured based on the magnetic field signal detected by the sensor, so that the total magnetic field is close to the zero flux state. The DC sensor converts the magnetic field change into an electrical signal, which is amplified by the DC amplifier to obtain a DC analog signal output.

[0075] The AC detection path 11 may include an AC sensor, an AC amplifier, an AC magnetic flux compensation circuit and other parts.

[0076] When the AC current to be measured passes through the AC sensor, a magnetic field that changes with time is generated. The AC flux compensation circuit monitors the magnetic field changes in real time and generates a corresponding compensation magnetic field so that the circuit can be close to the zero flux state at different times. The AC sensor converts the magnetic field changes into electrical signals, which are amplified by the AC amplifier to obtain AC analog signal output.

[0077] In another embodiment, a signal processing module can be added to the micro-current sensing circuit. The signal processing module can digitally process the analog signals output by the DC detection path and the AC detection path, for example, by using an analog-to-digital converter to convert the analog signals into digital signals, and then further process them through digital filters, amplifiers, etc. This can improve the anti-interference ability and accuracy of the signal, and also facilitate integration with digital systems.

[0078] The above-mentioned microcurrent sensing circuit includes a DC detection path and an AC detection path arranged in parallel. The DC detection path can detect the current to be measured based on DC flux compensation to obtain a DC analog signal; the AC detection path can detect the current to be measured based on AC flux compensation to obtain an AC analog signal. The microcurrent sensing circuit reaches a zero flux state under the action of DC flux compensation and AC flux compensation. The present application sets up a DC detection path and an AC detection path respectively, so that the detection of DC and AC microcurrents is more professional and precise. The zero flux state is reached under the action of DC flux compensation and AC flux compensation, which greatly reduces the influence of external interference magnetic fields on the measurement. Whether it is the detection of DC or AC current, it can be carried out in an almost interference-free environment, thereby significantly improving the measurement accuracy.

[0079] In an exemplary embodiment, based on the above embodiment, see Figure 2The DC detection path 10 includes a DC fluxgate circuit 101, a DC signal adjustment circuit 102, a DC feedback circuit 103 and a DC output circuit 104; the DC fluxgate circuit 101 is connected to the DC output circuit 104 through the DC signal adjustment circuit 102; the DC feedback circuit 103 is connected to the DC signal adjustment circuit 102 and the DC fluxgate circuit 101 respectively.

[0080] The DC fluxgate circuit 101 is used to generate a DC induction signal according to the current to be measured, and to make the micro-current sensing circuit reach a zero flux state under the effects of DC flux compensation and AC flux compensation.

[0081] In the embodiment of the present application, when the current to be measured passes through the DC fluxgate circuit, a magnetic field change will be generated in the circuit. The magnetic core and other components in the DC fluxgate circuit will respond to the magnetic field change and generate a corresponding DC induction signal. At the same time, in the entire micro-current sensing circuit, DC flux compensation and AC flux compensation work together to adjust the magnetic field so that the circuit reaches a zero flux state, reducing the impact of external interference on the measurement.

[0082] Another implementation method may use different types of magnetic core materials or optimize the structural design of the magnetic core to improve the adaptability and sensitivity of the DC fluxgate circuit to different current ranges to be measured.

[0083] The DC signal adjustment circuit 102 is used to perform DC signal adjustment processing on the DC sensing signal to obtain an adjusted DC sensing signal.

[0084] In the embodiment of the present application, the DC signal adjustment circuit may include components such as an amplifier and a filter. The amplifier is used to amplify the weak DC induction signal to increase the signal strength; the filter is used to remove noise and interference in the signal to improve the signal quality.

[0085] Another implementation method may use digital signal processing technology to adjust the DC sensing signal, such as using a digital filter and a digital amplifier, to improve the accuracy and flexibility of signal adjustment.

[0086] The DC feedback circuit 103 is used to generate a DC compensation circuit according to the adjusted induction signal to perform DC magnetic flux compensation.

[0087] In the embodiment of the present application, the DC feedback circuit monitors the adjusted induction signal and generates a corresponding DC compensation signal according to the characteristics of the signal. This compensation signal is fed back to the DC fluxgate circuit to adjust the magnetic field and realize DC flux compensation.

[0088] Another implementation method may use an intelligent control algorithm to generate a DC compensation signal, and dynamically adjust the size and direction of the compensation signal according to the real-time sensing signal and environmental conditions to improve the effect of DC flux compensation.

[0089] The DC output circuit 104 is used to output a DC analog signal outputted from the secondary side based on the adjusted DC sensing signal.

[0090] In the embodiment of the present application, the DC output circuit further processes and converts the adjusted DC sensing signal and outputs it in the form of a DC analog signal suitable for subsequent reception and processing by a subsequent device.

[0091] Another implementation may add signal isolation and protection functions, such as using an optocoupler isolator or a transient voltage suppressor, to improve the stability and reliability of the DC output circuit.

[0092] The embodiment of the present application generates a DC sensing signal through a DC fluxgate circuit, and combines the coordinated work of a DC signal adjustment circuit, a DC feedback circuit, and a DC output circuit to effectively remove noise and interference and improve the measurement accuracy of DC microcurrent. The combined effect of DC flux compensation and AC flux compensation enables the microcurrent sensing circuit to reach a zero flux state, reduces external magnetic field interference, and improves the stability of the circuit.

[0093] In an exemplary embodiment, based on the above embodiment, see Figure 3 The AC detection path includes an AC fluxgate circuit 111, an AC signal adjustment circuit 112, an AC feedback circuit 113 and an AC output circuit 114; the AC fluxgate circuit 111 is connected to the AC output circuit 114 through the AC signal adjustment circuit 112; the AC feedback circuit 113 is connected to the AC signal adjustment circuit 112 and the AC fluxgate circuit 111 respectively;

[0094] The AC fluxgate circuit 111 is used to generate an AC induction signal according to the current to be measured, and to make the micro-current sensing circuit reach a zero flux state under the effects of DC flux compensation and AC flux compensation.

[0095] In the embodiment of the present application, when the AC current to be measured passes through the AC fluxgate circuit, a magnetic field that changes with time will be generated in the circuit. The magnetic core and other components in the AC fluxgate circuit respond to this changing magnetic field and generate corresponding AC induction signals. At the same time, in the entire micro-current sensing circuit, DC flux compensation and AC flux compensation work together to adjust the magnetic field so that the circuit reaches a zero flux state, reducing the impact of external interference on AC current measurement.

[0096] Another implementation method may use a different magnetic core structure or optimize the magnetic core material to improve the response speed and sensitivity to alternating currents of different frequencies.

[0097] The AC signal adjustment circuit 112 is used to perform AC signal adjustment processing on the AC induction signal to obtain an adjusted AC induction signal.

[0098] In the embodiment of the present application, the AC signal adjustment circuit may include components such as an amplifier, a filter, and a rectifier. The amplifier is used to amplify weak AC induction signals; the filter is used to remove noise and interference outside a specific frequency range; and the rectifier can convert AC signals into DC signals for further processing.

[0099] Another implementation method may use digital signal processing technology to adjust the AC induction signal, such as using a digital filter and a digital amplifier, to improve the accuracy and flexibility of signal adjustment.

[0100] The AC feedback circuit 113 is used to generate an AC compensation current according to the adjusted induction signal to perform AC magnetic flux compensation.

[0101] In the embodiment of the present application, the AC feedback circuit monitors the adjusted induction signal and generates a corresponding AC compensation current according to the characteristics of the signal. This compensation current is fed back to the AC fluxgate circuit to adjust the magnetic field and realize AC flux compensation.

[0102] Another implementation method may use an adaptive control algorithm to generate an AC compensation current, and dynamically adjust the magnitude and phase of the compensation current according to the real-time sensing signal and environmental conditions to improve the effect of AC flux compensation.

[0103] The AC output circuit 114 is used to output an AC analog signal outputted from the secondary side based on the adjusted AC induction signal.

[0104] In the embodiment of the present application, the AC output circuit further processes and converts the adjusted AC induction signal and outputs it in the form of an AC analog signal suitable for subsequent reception and processing by a subsequent device.

[0105] Another implementation method: signal isolation and protection functions may be added, such as using an optocoupler isolator or a transient voltage suppressor, to improve the stability and reliability of the AC output circuit.

[0106] The embodiment of the present application generates an AC induction signal through an AC fluxgate circuit, and combines the coordinated work of an AC signal adjustment circuit, an AC feedback circuit, and an AC output circuit to effectively remove noise and interference and improve the measurement accuracy of AC microcurrent. The combined effect of DC flux compensation and AC flux compensation enables the microcurrent sensing circuit to reach a zero flux state, reduces external magnetic field interference, and improves the stability of the circuit.

[0107] In an exemplary embodiment, based on the above embodiment, see Figure 4The DC signal adjustment circuit 102 includes a DC resonant frequency selection circuit 1021, a DC differential amplifier circuit 1022, a DC analog-to-digital conversion circuit 1023 and a DC digital signal processing circuit 1024 which are connected in sequence; the DC resonant frequency selection circuit 1021 is connected to the DC fluxgate circuit 101; the DC digital signal processing circuit 1024 is respectively connected to the DC feedback circuit 103 and the DC output circuit 104;

[0108] The DC resonant frequency selection circuit 1021 is used to perform DC signal frequency selection processing on the DC induction signal to obtain a DC frequency signal.

[0109] In the embodiment of the present application, the DC resonant frequency selection circuit can select the frequency of the input DC induction signal through a resonant circuit composed of components such as capacitors and inductors, allowing only signals within a specific frequency range to pass through and removing interference signals of other frequencies.

[0110] Another implementation method may use a programmable filter to implement the frequency selection processing of the DC signal. By adjusting the parameters of the filter, it can adapt to different frequency ranges of the current to be measured.

[0111] The DC differential amplifier circuit 1022 is used to perform DC signal differential amplification processing on the DC frequency signal to obtain a DC differential amplified signal.

[0112] In the embodiment of the present application, the DC differential amplifier circuit can differentially amplify the input DC frequency signal, increase the amplitude of the signal, and suppress common mode interference. Differential amplification can effectively improve the signal-to-noise ratio of the signal and enhance the anti-interference ability of the circuit.

[0113] Another implementation method may use a multi-stage differential amplifier circuit to improve the amplification factor and signal quality.

[0114] The DC analog-to-digital conversion circuit 1023 is used to perform DC analog-to-digital conversion processing on the DC differential amplified signal to obtain a DC analog-to-digital conversion signal.

[0115] In the embodiment of the present application, the DC analog-to-digital conversion circuit can convert the analog DC differential amplified signal into a digital signal for subsequent digital signal processing. The analog-to-digital conversion can improve the accuracy and stability of the signal and facilitate integration with the digital system.

[0116] Another implementation may use a higher resolution analog-to-digital converter to improve the quantization accuracy of the signal.

[0117] The DC digital signal processing circuit 1024 is used to perform DC digital signal processing on the DC analog-to-digital conversion signal to obtain an adjusted DC sensing signal.

[0118] In the embodiment of the present application, the DC digital signal processing circuit may include a digital filter, an amplifier, an algorithm processor, etc. The digital filter can further remove noise and interference in the digital signal; the amplifier can adjust the amplitude of the signal; the algorithm processor can perform various algorithm processing on the signal, such as linearization, calibration, etc., to improve the quality and accuracy of the signal.

[0119] Another implementation method may use more advanced digital signal processing algorithms, such as adaptive filtering, neural network algorithms, etc., to improve the effect of signal processing.

[0120] In the embodiment of the present application, through the coordinated work of the DC resonant frequency selection circuit, the DC differential amplifier circuit, the DC analog-to-digital conversion circuit and the DC digital signal processing circuit, noise and interference can be effectively removed and the quality of the DC sensing signal can be improved. Differential amplification and digital signal processing can suppress common-mode interference, improve the anti-interference ability of the circuit, and ensure the accuracy of measurement.

[0121] In an exemplary embodiment, based on the above embodiment, see Figure 5 The above-mentioned AC signal adjustment circuit 112 includes an AC resonant frequency selection circuit 1121, an AC differential amplifier circuit 1122, an AC analog-to-digital conversion circuit 1123 and an AC digital signal processing circuit 1124 connected in sequence; the AC resonant frequency selection circuit 1121 is connected to the AC fluxgate circuit 111; and the AC digital signal processing circuit 114 is respectively connected to the AC feedback circuit 113 and the AC output circuit 114.

[0122] The AC resonant frequency selection circuit 1121 is used to perform AC signal frequency selection processing on the AC induction signal to obtain an AC frequency signal.

[0123] In the embodiment of the present application, the AC resonant frequency selection circuit is composed of components such as inductors and capacitors, and screens the input AC induction signal according to a specific resonant frequency. It can remove unnecessary frequency components and only retain AC signals within a specific frequency range, thereby improving the purity and quality of the signal.

[0124] Another implementation method may use a programmable digital filter to implement frequency selection processing of AC signals. By adjusting the parameters of the filter, it can meet the detection requirements of AC signals of different frequencies.

[0125] The AC differential amplifier circuit 1122 is used to perform AC signal differential amplification processing on the AC frequency signal to obtain an AC differential amplified signal.

[0126] In the embodiment of the present application, the AC differential amplifier circuit can perform differential amplification on the input AC frequency signal, enhance the amplitude of the signal, and suppress common mode noise at the same time. It can improve the signal-to-noise ratio of the signal and make subsequent processing more accurate.

[0127] Another implementation method may use a multi-stage differential amplification structure to further improve the amplification factor and signal quality.

[0128] The AC analog-to-digital conversion circuit 1123 is used to perform AC analog-to-digital conversion processing on the AC differential amplified signal to obtain an AC analog-to-digital conversion signal.

[0129] In the embodiment of the present application, the AC analog-to-digital conversion circuit converts the analog AC differential amplified signal into a digital signal for digital signal processing, which can improve the accuracy and stability of the signal and facilitate integration with the digital system.

[0130] Another implementation method may use an analog-to-digital converter with a higher resolution to improve the quantization accuracy of the signal.

[0131] The AC digital signal processing circuit 1124 is used to perform AC digital signal processing on the AC analog-to-digital conversion signal to obtain an adjusted AC sensing signal.

[0132] In the embodiment of the present application, the AC digital signal processing circuit may include a digital filter, an amplifier, an algorithm processor, etc. It can further filter, amplify and perform algorithm processing on the input digital signal to remove noise, enhance signal characteristics, and improve signal quality and accuracy.

[0133] Another implementation method may use more advanced digital signal processing algorithms, such as adaptive filtering, wavelet transform, etc., to improve the effect of signal processing.

[0134] In the embodiment of the present application, through the coordinated work of the AC resonant frequency selection circuit, the AC differential amplifier circuit, the AC analog-to-digital conversion circuit and the AC digital signal processing circuit, noise and interference can be effectively removed and the quality of the AC induction signal can be improved. Enhanced anti-interference ability: Differential amplification and digital signal processing can suppress common-mode noise, improve the anti-interference ability of the circuit, and ensure the accuracy of AC current measurement.

[0135] In an exemplary embodiment, based on the above embodiment, see Figure 6 The above-mentioned AC fluxgate circuit includes a first magnetic core circuit and a second magnetic core circuit; the first magnetic core circuit includes a first excitation coil, a first induction coil and a first magnetic core; the second magnetic core circuit includes a second excitation coil, a second induction coil, a feedback coil and a second magnetic core; the first excitation coil and the first induction coil are wound on the first magnetic core; the second excitation coil, the second induction coil and the feedback coil are wound on the second magnetic core; the first excitation coil is connected to the second excitation coil; the first excitation coil is also used to connect the excitation source circuit outside the micro-current sensor circuit; the first induction coil is connected to the signal adjustment circuit through the second induction coil; the feedback coil is connected to the feedback circuit;

[0136] The first excitation coil is used to generate a first alternating magnetic field according to the current to be measured.

[0137] In the embodiment of the present application, when the alternating current to be measured passes through the first excitation coil, an alternating magnetic field is generated around the first magnetic core according to the principle of electromagnetic induction.

[0138] Another implementation manner may adjust the number of turns, wire diameter and other parameters of the first excitation coil to optimize the intensity and frequency response of the generated alternating magnetic field.

[0139] The first induction coil is used to detect the magnetic field change of the first alternating magnetic field and generate a first alternating induction current.

[0140] In the embodiment of the present application, the first induction coil can generate an alternating current related to the change in the magnetic field by sensing the change in the first alternating magnetic field.

[0141] Another implementation method may use different coil winding methods or materials to improve the sensitivity and linearity of the induction coil.

[0142] The second excitation coil is used to generate a second alternating magnetic field according to the current to be measured.

[0143] Similar to the first excitation coil, in the embodiment of the present application, when the alternating current to be measured passes through the second excitation coil, an alternating magnetic field is generated around the second magnetic core.

[0144] Another implementation method may be to perform special shielding on the second excitation coil to reduce the influence of external interference on the alternating magnetic field generated by the second excitation coil.

[0145] The second induction coil is used to detect the magnetic field change of the second alternating magnetic field and generate a second alternating induction current.

[0146] The embodiment of the present application can sense the change of the second alternating magnetic field, generate a corresponding alternating induced current, and transmit it to the signal adjustment circuit.

[0147] Another implementation method may increase the number of layers of the second induction coil to improve the induction capability.

[0148] The feedback coil is used to generate a compensation magnetic field according to the AC compensation current.

[0149] In the embodiment of the present application, when the feedback circuit provides an AC compensation current through the feedback coil, a compensation magnetic field is generated, which can adjust the magnetic field distribution in the entire AC fluxgate circuit to achieve better measurement accuracy.

[0150] Another implementation may change the position or orientation of the feedback coil to optimize the effect of the compensation magnetic field.

[0151] In the embodiment of the present application, the measurement accuracy of the AC microcurrent can be effectively improved through the coordinated work of the two magnetic core circuits and the compensation effect of the feedback coil. The multi-coil structure and compensation mechanism can reduce the influence of external magnetic field interference on the measurement results.

[0152] In an exemplary embodiment, based on the above embodiment, see Figure 7 The above-mentioned AC feedback circuit 113 includes an AC digital-to-analog conversion circuit 1131, an AC control voltage generating circuit 1132 and an AC voltage-controlled current source circuit 1133 connected in sequence; the AC digital-to-analog conversion circuit 1131 is connected to the AC signal adjustment circuit 112; and the AC voltage-controlled current source circuit 1133 is connected to the AC fluxgate circuit 111.

[0153] The AC digital-to-analog conversion circuit 1131 is used to perform AC digital-to-analog conversion processing on the adjusted AC induction signal to obtain an AC feedback signal.

[0154] The embodiment of the present application can convert the adjusted AC induction signal in digital form from the AC signal adjustment circuit into an analog signal for subsequent processing. This process is usually implemented by a digital-to-analog converter (DAC) to convert different levels of the digital signal into corresponding analog voltage values.

[0155] Another implementation method may use a higher precision digital-to-analog converter to improve the accuracy and stability of the conversion, or use a parallel digital-to-analog conversion structure to speed up the conversion.

[0156] The AC control voltage generating circuit 1132 is used to perform AC voltage conversion processing on the AC feedback signal to obtain an AC control voltage.

[0157] The embodiment of the present application can receive the analog feedback signal output by the AC digital-to-analog conversion circuit, and convert it into a voltage signal suitable for controlling the AC voltage-controlled current source through a specific circuit structure. This process may involve operations such as amplification, filtering, and voltage stabilization to ensure that the output control voltage is stable and within a suitable range.

[0158] Another implementation method may be to use a programmable voltage conversion chip and adjust parameters through software to adapt to different application scenarios, or to use a feedback control loop to adjust the output voltage in real time to improve stability.

[0159] The AC voltage-controlled current source circuit 1133 is used to perform AC voltage-current conversion processing on the AC control voltage to obtain an AC compensation current.

[0160] In the embodiment of the present application, a corresponding AC compensation current can be generated according to the input AC control voltage. Usually, a voltage-controlled current source (VCCS) circuit is used to implement it. By adjusting the parameters of the components in the circuit, the output current can be made proportional to the input voltage. This AC compensation current is fed back to the AC fluxgate circuit to achieve AC flux compensation.

[0161] Another implementation method may use a digitally controlled voltage-controlled current source to adjust the current output through a microprocessor or digital signal processor (DSP) to improve accuracy and flexibility, or use a multi-stage voltage-controlled current source structure to expand the current output range.

[0162] In the embodiment of the present application, through precise digital-to-analog conversion, voltage conversion and current source control, an AC compensation current can be accurately generated to achieve effective AC flux compensation, thereby improving the measurement accuracy of the AC microcurrent. Different implementation methods can be selected and adjusted according to specific needs to adapt to different measurement conditions and requirements. For example, the accuracy of the digital-to-analog converter, the parameters of the control voltage generation circuit and the characteristics of the voltage-controlled current source can be adjusted to meet the AC microcurrent measurement of different ranges.

[0163] In an exemplary embodiment, based on the above embodiment, see Figure 8 The AC output circuit 114 includes an AC amplifier circuit 1141 and an AC analog output circuit 1142 connected in sequence; the AC amplifier circuit 1141 is connected to the AC signal adjustment circuit 1142.

[0164] The AC amplifier circuit 1141 is used to amplify the AC current signal on the secondary side to obtain an amplified AC current signal.

[0165] The embodiment of the present application can receive an AC current signal output from an AC signal adjustment circuit and amplify its amplitude through an amplifier. An amplifier circuit can be constructed using devices such as an operational amplifier, and a suitable amplification factor and frequency response characteristics can be selected according to the characteristics of the input signal.

[0166] Another implementation method may use a multi-stage amplification structure to improve the amplification factor and signal quality, or use a programmable amplifier to adjust the amplification factor through an external control signal to adapt to different input signal strengths.

[0167] The AC analog output circuit 1142 is used to perform AC signal conversion processing on the amplified AC current signal to obtain an AC analog signal.

[0168] The embodiment of the present application can further process the amplified AC current signal and convert it into an AC analog signal form suitable for subsequent equipment to receive and process. This may involve operations such as signal filtering, level adjustment, impedance matching, etc. to ensure that the output AC analog signal is stable, accurate and compatible with subsequent equipment.

[0169] Another implementation method can add signal isolation function, such as using optocoupler isolators or transformer isolation to improve the anti-interference ability and safety of the output signal. Or adopt a digital analog mixed output mode, providing both digital interface and analog interface to meet the needs of different devices.

[0170] In the embodiment of the present application, the AC amplifier circuit can amplify the weak AC current signal to a suitable amplitude, which is convenient for subsequent processing and measurement. This helps to improve the accuracy and reliability of the measurement, especially for small-amplitude AC micro-current signals. The AC analog output circuit can convert the processed signal into a standard AC analog signal form, which is compatible with a variety of different measurement devices and systems. This makes it easy to integrate the micro-current sensing circuit into different application scenarios.

[0171] In an exemplary embodiment, based on the above embodiment, the AC fluxgate circuit has the same structure as the DC fluxgate circuit; the AC feedback circuit has the same structure as the DC feedback circuit; and the AC output circuit has the same structure as the DC output circuit.

[0172] In one embodiment, Fig. 9 As shown, the present application also provides a microcurrent sensing system, which includes the above-mentioned microcurrent sensing circuit 1 and excitation source circuit 2; the excitation source circuit 2 is connected to the microcurrent sensing circuit 1; the microcurrent sensing circuit 2 includes a DC detection path 10 and an AC detection path 11 arranged in parallel.

[0173] In an embodiment of the present application, the excitation source circuit 2 can generate an excitation signal of specific frequency and amplitude according to the requirements of the microcurrent sensing circuit, and transmit it to the corresponding components in the microcurrent sensing circuit through connecting lines, such as the excitation coils of the DC fluxgate circuit and the AC fluxgate circuit.

[0174] In another implementation mode, the excitation source circuit can realize PWM square wave output square wave signal by the timer of the single-chip microcomputer, including isolation and decoupling circuit, level flipping circuit, and dual power supply circuit; the level flipping circuit can realize positive and negative square waves, and can realize the excitation source by using a high-speed analog switch or a multiplexer for processing; the dual power supply circuit contains two excitation frequencies, so that the excitation signals at both ends are in opposite directions, so that the waveform generated by the entire excitation signal is more stable.

[0175] The DC detection path 10 is used to detect the current to be measured based on the DC magnetic flux compensation to obtain a DC analog signal. The AC detection path 11 is used to detect the current to be measured based on the AC magnetic flux compensation to obtain an AC analog signal; wherein the micro-current sensing circuit 01 reaches a zero magnetic flux state under the action of the DC magnetic flux compensation and the AC magnetic flux compensation.

[0176] In the embodiment of the present application, the DC detection path 10 can detect the current to be measured based on the DC flux compensation to obtain a DC analog signal. When the DC current to be measured passes through, a magnetic field change is generated, and components such as the DC fluxgate circuit sense and process it, and finally output a DC analog signal after passing through the DC signal adjustment circuit, the DC feedback circuit and other links.

[0177] The AC detection path 11 detects the current to be measured based on AC flux compensation to obtain an AC analog signal. The AC current to be measured generates a magnetic field that changes with time, which is sensed and processed by components such as the AC fluxgate circuit, and finally outputs an AC analog signal after passing through the AC signal adjustment circuit, AC feedback circuit and other links.

[0178] In the embodiment of the present application, by designing the DC detection path and the AC detection path separately and applying the magnetic flux compensation technology, high-precision detection of DC and AC microcurrents can be achieved. The excitation source circuit is adjustable and can adapt to different measurement requirements and environmental conditions, thereby improving the adaptability of the system.

[0179] In an exemplary embodiment, based on the above embodiment, see Fig.10 , the above-mentioned micro-current sensing system further includes a temperature acquisition circuit 3; the temperature acquisition circuit 3 is connected to the micro-current sensing circuit 1;

[0180] The temperature acquisition circuit 3 is used to detect the ambient temperature, and when the ambient temperature meets the preset temperature, correct the DC analog signal and the AC analog signal to obtain corrected DC analog signal and AC analog signal.

[0181] In an embodiment of the present application, the temperature acquisition circuit may be composed of a temperature sensor and a related signal processing circuit. The temperature sensor detects the temperature of the surrounding environment and converts the temperature signal into an electrical signal. The signal processing circuit analyzes the temperature signal to determine whether the ambient temperature meets the preset temperature range. If so, the DC analog signal and the AC analog signal from the microcurrent sensing circuit are corrected according to a predetermined temperature and signal correction relationship. For example, the signal can be adjusted accordingly according to different temperature values ​​by means of a lookup table, formula calculation or intelligent algorithm to eliminate the influence of temperature on microcurrent detection.

[0182] Another implementation method can use a high-precision digital temperature sensor to improve the accuracy of temperature detection. At the same time, a more complex adaptive correction algorithm can be used to dynamically adjust the correction parameters according to real-time temperature changes to better adapt to different working environments. The NTCLG100E2 temperature sensor can be used in the design of the temperature acquisition circuit. The ADC inside the DSP collects and converts the voltage signal to achieve accurate temperature monitoring in a high-temperature environment.

[0183] The embodiment of the present application takes into account the influence of temperature on microcurrent detection, and corrects the analog signal through the temperature acquisition circuit, which can significantly improve the measurement accuracy of DC and AC microcurrents, especially in an environment with large temperature changes, reducing the measurement error caused by temperature factors, so that the microcurrent sensing system can maintain stable performance under different temperature conditions, thereby improving the reliability of the system.

[0184] In an exemplary embodiment, based on the above embodiment, as Fig.11 As shown, by measuring the DC voltage signal formed by the compensation current on the load resistor RL, the size of the primary side current signal is calculated proportionally, thereby realizing high-precision DC current measurement, and measuring the DC current and its high-frequency ripple component or AC current.

[0185] When current flows through the primary winding, according to the monotonic linear following relationship between current and magnetic flux, the primary current will generate a current magnetic flux highly correlated with it in the annular core. The two sets of excitation windings of the fluxgate sensing circuit will generate corresponding induction signals according to this magnetic flux and output them to the fluxgate circuit connected to it. The fluxgate circuit then converts this induction signal into a voltage signal and outputs it to the amplifier circuit after superposition. After amplification by the amplifier circuit, a secondary current is generated in the secondary current line. This secondary current will generate a secondary current magnetic flux highly correlated with it in the annular core. The secondary current magnetic flux is opposite to the primary current magnetic flux, and finally the sum of the primary current magnetic flux and the secondary current magnetic flux is zero, so that the ampere-turn ratio of the primary current is equal to the ampere-turn ratio of the secondary current.

[0186] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0187] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A micro-current sensing circuit, characterized in that: The micro-current sensing circuit comprises a DC detection path and an AC detection path arranged in parallel; The DC detection path is used to detect the current to be measured based on DC flux compensation to obtain a DC analog signal; The AC detection path is used to detect the current to be measured based on AC flux compensation to obtain an AC analog signal; Wherein, the micro-current sensing circuit reaches a zero flux state under the effects of DC flux compensation and AC flux compensation.

2. The micro-current sensing circuit according to claim 1, characterized in that: The DC detection path includes a DC fluxgate circuit, a DC signal adjustment circuit, a DC feedback circuit and a DC output circuit; the DC fluxgate circuit is connected to the DC output circuit through the DC signal adjustment circuit; the DC feedback circuit is connected to the DC signal adjustment circuit and the DC fluxgate circuit respectively; The DC fluxgate circuit is used to generate a DC induction signal according to the current to be measured, and to make the micro-current sensing circuit reach a zero flux state under the action of DC flux compensation and AC flux compensation; The DC signal adjustment circuit is used to perform DC signal adjustment processing on the DC sensing signal to obtain an adjusted DC sensing signal; The DC feedback circuit is used to generate a DC compensation circuit according to the adjusted induction signal to perform DC magnetic flux compensation; The DC output circuit is used to output a DC analog signal output on the secondary side based on the adjusted DC induction signal.

3. The micro-current sensing circuit according to claim 2, characterized in that: The AC detection path includes an AC fluxgate circuit, an AC signal adjustment circuit, an AC feedback circuit and an AC output circuit; the AC fluxgate circuit is connected to the AC output circuit through the AC signal adjustment circuit; the AC feedback circuit is connected to the AC signal adjustment circuit and the AC fluxgate circuit respectively; The AC fluxgate circuit is used to generate an AC induction signal according to the current to be measured, and to make the micro-current sensing circuit reach a zero flux state under the action of DC flux compensation and AC flux compensation; The AC signal adjustment circuit is used to perform AC signal adjustment processing on the AC induction signal to obtain an adjusted AC induction signal; The AC feedback circuit is used to generate an AC compensation current according to the adjusted induction signal to perform AC magnetic flux compensation; The AC output circuit is used to output an AC analog signal output on the secondary side based on the adjusted AC induction signal.

4. The micro-current sensing circuit according to claim 3, characterized in that: The DC signal adjustment circuit includes a DC resonant frequency selection circuit, a DC differential amplifier circuit, a DC analog-to-digital conversion circuit and a DC digital signal processing circuit connected in sequence; the DC resonant frequency selection circuit is connected to the DC fluxgate circuit; the DC digital signal processing circuit is respectively connected to the DC feedback circuit and the DC output circuit; The DC resonant frequency selection circuit is used to perform DC signal frequency selection processing on the DC induction signal to obtain a DC frequency signal; The DC differential amplifier circuit is used to perform DC signal differential amplification processing on the DC frequency signal to obtain a DC differential amplified signal; The DC analog-to-digital conversion circuit is used to perform DC analog-to-digital conversion processing on the DC differential amplification signal to obtain a DC analog-to-digital conversion signal; The DC digital signal processing circuit is used to perform DC digital signal processing on the DC analog-to-digital conversion signal to obtain the adjusted DC sensing signal.

5. The micro-current sensing circuit according to claim 3, characterized in that: The AC signal adjustment circuit includes an AC resonant frequency selection circuit, an AC differential amplifier circuit, an AC analog-to-digital conversion circuit and an AC digital signal processing circuit connected in sequence; the AC resonant frequency selection circuit is connected to the AC fluxgate circuit; the AC digital signal processing circuit is respectively connected to the AC feedback circuit and the AC output circuit; The AC resonant frequency selection circuit is used to perform AC signal frequency selection processing on the AC induction signal to obtain an AC frequency signal; The AC differential amplifier circuit is used to perform AC signal differential amplification processing on the AC frequency signal to obtain an AC differential amplified signal; The AC analog-to-digital conversion circuit is used to perform AC analog-to-digital conversion processing on the AC differential amplified signal to obtain an AC analog-to-digital conversion signal; The AC digital signal processing circuit is used to perform AC digital signal processing on the AC analog-to-digital conversion signal to obtain the adjusted AC induction signal.

6. The micro-current sensing circuit according to claim 3, characterized in that: The AC fluxgate circuit includes a first magnetic core circuit and a second magnetic core circuit; the first magnetic core circuit includes a first excitation coil, a first induction coil and a first magnetic core; the second magnetic core circuit includes a second excitation coil, a second induction coil, a feedback coil and a second magnetic core; the first excitation coil and the first induction coil are wound on the first magnetic core; the second excitation coil, the second induction coil and the feedback coil are wound on the second magnetic core; the first excitation coil is connected to the second excitation coil; the first excitation coil is also used to connect the excitation source circuit outside the micro-current sensing circuit; the first induction coil is connected to the signal adjustment circuit through the second induction coil; the feedback coil is connected to the feedback circuit; The first excitation coil is used to generate a first alternating magnetic field according to the current to be measured; The first induction coil is used to detect the magnetic field change of the first alternating magnetic field and generate a first alternating induction current; The second excitation coil is used to generate a second alternating magnetic field according to the current to be measured; The second induction coil is used to detect the magnetic field change of the second alternating magnetic field and generate a second alternating induction current; The feedback coil is used to generate a compensation magnetic field according to the AC compensation current.

7. The micro-current sensing circuit according to claim 3, characterized in that: The AC feedback circuit comprises an AC digital-to-analog conversion circuit, an AC control voltage generation circuit and an AC voltage-controlled current source circuit connected in sequence; the AC digital-to-analog conversion circuit is connected to the AC signal adjustment circuit; the AC voltage-controlled current source circuit is connected to the AC fluxgate circuit; The AC digital-to-analog conversion circuit is used to perform AC digital-to-analog conversion processing on the adjusted AC induction signal to obtain an AC feedback signal; The AC control voltage generating circuit is used to perform AC voltage conversion processing on the AC feedback signal to obtain an AC control voltage; The AC voltage-controlled current source circuit is used to perform AC voltage-to-current conversion processing on the AC control voltage to obtain the AC compensation current.

8. The micro-current sensing circuit according to claim 3, characterized in that: The AC output circuit includes an AC amplifying circuit and an AC analog output circuit connected in sequence; the AC amplifying circuit is connected to the AC signal adjusting circuit; The AC amplifying circuit is used to amplify the AC current signal on the secondary side to obtain an amplified AC current signal; The AC analog output circuit is used to perform AC signal conversion processing on the amplified AC current signal to obtain the AC analog signal.

9. The micro-current sensing circuit according to any one of claims 3 to 8, characterized in that: The AC fluxgate circuit has the same structure as the DC fluxgate circuit; the AC feedback circuit has the same structure as the DC feedback circuit; and the AC output circuit has the same structure as the DC output circuit.

10. A micro-current sensing system, characterized in that: The microcurrent sensing system comprises an excitation source circuit and a microcurrent sensing circuit as claimed in any one of claims 1 to 9; the excitation source circuit is connected to the microcurrent sensing circuit; the microcurrent sensing circuit comprises a DC detection path and an AC detection path arranged in parallel; The excitation source circuit is used to generate the current to be measured; The DC detection path is used to detect the current to be measured based on DC flux compensation to obtain a DC analog signal; The AC detection path is used to detect the current to be measured based on AC magnetic flux compensation to obtain an AC analog signal; Wherein, the micro-current sensing circuit reaches a zero flux state under the effects of DC flux compensation and AC flux compensation.

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