Zero-flux closed-loop circuit

Abstract

The invention relates to a zero-flux closed-loop circuit which comprises a self-oscillation fluxgate current sensor, a magnetic integrator and a feedback circuit. Wherein the self-oscillation fluxgate current sensor can generate a magnetic field signal under the action of excitation current, the magnetic integrator can generate a corresponding voltage signal according to the magnetic field signal, the feedback circuit can generate a feedback signal according to the magnetic field intensity corresponding to the voltage signal, and the feedback signal acts on the self-oscillation fluxgate current sensor. Therefore, the self-oscillation fluxgate current sensor adjusts the excitation current, thereby ensuring that the magnetic flux of a fluxgate of the self-oscillation fluxgate current sensor is kept near a zero magnetic flux point. Therefore, through the zero-magnetic-flux closed-loop circuit, the electrified current of the electrified wire can be detected in a zero-magnetic-flux environment, the influence of noise can be effectively reduced, the distortion degree of signals is reduced, and the precision of current detection is improved.

Description

Technical Field

[0001] The present application relates to the technical field of zero magnetic flux circuits, and in particular to a zero magnetic flux closed-loop circuit. Background Art

[0002] In today's life, there are various circuit systems. Detecting the current of these circuit systems can ensure that they are in normal working state. The traditional way is to use a self-excited oscillation fluxgate current sensor to detect the current of the circuit system. However, the measurement accuracy of the self-excited oscillation fluxgate current sensor is low when it is interfered by the external magnetic field. Summary of the invention

[0003] Based on this, it is necessary to provide a zero-flux closed-loop circuit with high measurement accuracy.

[0004] A zero flux closed-loop circuit is provided, comprising:

[0005] A self-excited oscillation fluxgate current sensor, wherein a current-carrying conductor passes through a fluxgate of the self-excited oscillation fluxgate current sensor; the self-excited oscillation fluxgate current sensor is used to generate an excitation current to sense the current of the current-carrying conductor, and the self-excited oscillation fluxgate current sensor generates a magnetic field signal under the action of the excitation current;

[0006] A magnetic integrator, wherein the input end of the magnetic integrator is connected to the output end of the self-excited oscillation fluxgate current sensor, and the magnetic integrator is used to generate a voltage signal according to the magnetic field signal;

[0007] A feedback circuit, wherein the output end of the feedback circuit is connected to the self-excited oscillation fluxgate current sensor, and the input end of the feedback circuit is connected to the magnetic integrator; the feedback circuit is used to generate a feedback signal according to the magnetic field strength corresponding to the voltage signal and transmit the feedback signal to the self-excited oscillation fluxgate current sensor, so that the self-excited oscillation fluxgate current sensor adjusts the excitation current so that the magnetic flux passing through the fluxgate is maintained within a preset range;

[0008] The preset range is a magnetic field range with a zero magnetic flux point as the center and a floating preset value.

[0009] In one embodiment, the self-excited oscillation fluxgate current sensor comprises: a small current fluxgate current sensor, a first magnetic field signal generating module, a large current fluxgate current sensor, a second magnetic field signal generating module, a switch tube and a first comparator;

[0010] Wherein, the first pole of the switch tube is connected to the output end of the small current fluxgate current sensor, and the second pole of the switch tube is connected to the input end of the first magnetic field signal generating module;

[0011] The input end of the first comparator is connected to the output end of the large current fluxgate current sensor, the reference end of the first comparator is used to access the reference voltage, the output end of the first comparator is connected to the third pole of the switch tube, and the first comparator is used to:

[0012] When the output voltage of the high-current fluxgate current sensor is greater than the reference voltage, the switch tube is turned off to make the high-current fluxgate current sensor output voltage to the second magnetic field signal generating module;

[0013] When the output voltage of the large current fluxgate current sensor is less than or equal to the reference voltage, the switch tube is turned on to make the small current fluxgate current sensor output voltage to the first magnetic field signal generating module.

[0014] In one embodiment, the circuit structures of the large current fluxgate current sensor and the small current fluxgate current sensor are the same, and the large current fluxgate current sensor includes:

[0015] A first induction coil, the first induction coil is used to sense the magnetic field generated by the energized wire;

[0016] a first resistor, wherein a first end of the first resistor is connected to a first end of the first induction coil, and a second end of the first resistor is grounded;

[0017] a second comparator, wherein a first input terminal of the second comparator is connected to a first terminal of the first resistor, a second input terminal of the second comparator is connected to a second terminal of the first induction coil, and an output terminal of the second comparator is connected to a first terminal of the first induction coil;

[0018] A second resistor, wherein a first end of the second resistor is connected to the second end of the first induction coil, and a second end of the second resistor is grounded.

[0019] In one embodiment, the large current fluxgate current sensor further comprises:

[0020] a second induction coil, wherein a first end of the second induction coil is connected to an output end of the second comparator, and a second end of the second induction coil is grounded;

[0021] The directions of the same-named ends of the first induction coil and the second induction coil are opposite, and the number of winding turns of the first induction coil and the second induction coil are the same.

[0022] In one embodiment, the large current fluxgate current sensor further comprises:

[0023] a third resistor, the third resistor being connected in series between the first end of the first induction coil and the first input end of the second comparator;

[0024] a fourth resistor, the fourth resistor being connected in series between the first end of the first induction coil and the output end of the second comparator;

[0025] A fifth resistor, one end of the fifth resistor is connected to the second end of the second induction coil, and the other end of the fifth resistor is grounded.

[0026] In one embodiment, the feedback circuit comprises:

[0027] an amplifying module, wherein an input end of the amplifying module is connected to an output end of the magnetic integrator;

[0028] An analog-to-digital conversion module, the input end of the analog-to-digital conversion module is connected to the output end of the amplification module;

[0029] The control circuit has an input end connected to the output end of the analog-to-digital conversion module, and an output end of the control circuit connected to a self-excited oscillation fluxgate current sensor.

[0030] In one embodiment, the zero flux closed-loop circuit further includes:

[0031] The stabilized power supply is used to provide working voltage for the magnetic integrator and the feedback circuit respectively.

[0032] In one embodiment, the above-mentioned voltage-stabilized power supply includes:

[0033] Power module;

[0034] The operational amplifier, the voltage source and the switch module are connected in series between the output end and the controlled end of the power module.

[0035] In one embodiment, the above-mentioned voltage-stabilized power supply further includes:

[0036] The rectifier and filter module is connected in series between the operational amplifier and the voltage source.

[0037] In one embodiment, the above-mentioned voltage-stabilized power supply further includes:

[0038] The voltage divider module is connected in series between the operational amplifier and the rectifier and filter module.

[0039] The above-mentioned zero flux closed-loop circuit includes a self-excited oscillation fluxgate current sensor, a magnetic integrator and a feedback circuit, wherein the self-excited oscillation fluxgate current sensor can generate a magnetic field signal under the action of an excitation current, the magnetic integrator can generate a corresponding voltage signal according to the magnetic field signal, and the feedback circuit can generate a feedback signal according to the magnetic field strength corresponding to the voltage signal, and act on the self-excited oscillation fluxgate current sensor, so that the self-excited oscillation fluxgate current sensor adjusts the excitation current, thereby ensuring that the magnetic flux passing through the fluxgate of the self-excited oscillation fluxgate current sensor remains near the zero flux point. Therefore, the zero flux closed-loop circuit can detect the current of the current-carrying conductor in a zero flux environment, which can effectively reduce the influence of noise and reduce the degree of signal distortion, thereby improving the accuracy of current detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 One of the structural block diagrams of a zero flux closed-loop circuit of an embodiment;

[0042] Figure 2 A structural block diagram of a self-excited oscillation fluxgate current sensor according to an embodiment;

[0043] Figure 3 This is a second structural block diagram of a zero flux closed-loop circuit of an embodiment;

[0044] Figure 4 This is the third structural block diagram of a zero flux closed-loop circuit of an embodiment. DETAILED DESCRIPTION

[0045] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0047] It is understood that the terms "first", "second", etc. used in the present application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of the present application, the first magnetic field signal generating module may be referred to as the second magnetic field signal generating module, and similarly, the second magnetic field signal generating module may be referred to as the first magnetic field signal generating module. Both the first magnetic field signal generating module and the second magnetic field signal generating module are magnetic field signal generating modules, but they are not the same magnetic field signal generating module.

[0048] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0049] It can be understood that “at least one” means one or more, “plurality” means two or more, and “at least part of an element” means part or all of an element.

[0050] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0051] In one embodiment, Figure 1 As shown, a zero flux closed-loop circuit 10 is provided, comprising: a self-excited oscillation fluxgate current sensor 102 , a magnetic integrator 104 and a feedback circuit 106 .

[0052] Among them, a current-carrying conductor passes through the flux gate of the self-excited oscillation fluxgate current sensor 102; the self-excited oscillation fluxgate current sensor 102 is used to generate an excitation current to sense the current of the current-carrying conductor, and the self-excited oscillation fluxgate current sensor 102 generates a magnetic field signal under the action of the excitation current.

[0053] An input end of the magnetic integrator 104 is connected to an output end of the self-excited oscillation fluxgate current sensor 102 , and the magnetic integrator 104 is used to generate a voltage signal according to the magnetic field signal.

[0054] The output end of the feedback circuit 106 is connected to the self-excited oscillation fluxgate current sensor 102, and the input end of the feedback circuit 106 is connected to the magnetic integrator 104; the feedback circuit 106 is used to generate a feedback signal according to the magnetic field strength corresponding to the voltage signal and transmit it to the self-excited oscillation fluxgate current sensor 102, so that the self-excited oscillation fluxgate current sensor 102 adjusts the excitation current so that the magnetic flux passing through the fluxgate is maintained within a preset range.

[0055] The preset range is a magnetic field range with a floating preset value around the zero flux point. The smaller the floating preset value is, the closer the magnetic flux passing through the flux gate is to the zero flux point, and the more accurate the result of the current detection is when the current is closer to the zero flux point.

[0056] The self-excited oscillation fluxgate current sensor 102 includes a built-in oscillation circuit, which generates an excitation current. The magnetic field generated by the excitation current and the magnetic field generated by the current are superimposed on each other in space, thereby determining a magnetic field signal. Since the self-excited oscillation fluxgate current sensor 102 can work by using the magnetic field generated by the current without connecting to an external power supply, the working state of the self-excited oscillation fluxgate current sensor 102 depends on the magnitude and direction of the current. Among them, the magnetic field signal is positively correlated with the current.

[0057] The magnetic integrator 104 can generate a voltage signal proportional to the current according to the magnetic field signal, and the current can be measured by analyzing the voltage signal. In addition, the magnetic integrator 104 can also suppress the inductive modulation ripple caused by the transformer effect, thereby improving the stability of the zero flux closed-loop circuit 10.

[0058] The feedback circuit 106 generates a feedback signal according to the magnetic field strength corresponding to the voltage signal generated by the magnetic integrator 104, and transmits the feedback signal to the self-excited oscillation fluxgate current sensor 102, so that the self-excited oscillation fluxgate current sensor 102 adjusts the excitation current according to the feedback signal, so that the magnetic field generated by the excitation current after feedback adjustment is sufficient to counteract the magnetic field generated by the current, so as to ensure that the magnetic flux passing through the flux gate of the self-excited oscillation fluxgate current sensor 102 is maintained near the zero flux point, thereby realizing the detection of the current of the current-carrying conductor in a zero flux environment.

[0059] The above-mentioned zero flux closed-loop circuit 10 includes a self-excited oscillation fluxgate current sensor 102, a magnetic integrator 104 and a feedback circuit 106, wherein the self-excited oscillation fluxgate current sensor 102 can generate a magnetic field signal under the action of an excitation current, the magnetic integrator 104 can generate a corresponding voltage signal according to the magnetic field signal, and the feedback circuit 106 can generate a feedback signal according to the magnetic field strength corresponding to the voltage signal, and act on the self-excited oscillation fluxgate current sensor 102, so that the self-excited oscillation fluxgate current sensor 102 adjusts the excitation current, thereby ensuring that the magnetic flux passing through the fluxgate of the self-excited oscillation fluxgate current sensor 102 is kept near the zero flux point. Therefore, the zero flux closed-loop circuit 10 can detect the current of the current-carrying conductor in a zero flux environment, which can effectively reduce the influence of noise and reduce the degree of signal distortion, thereby improving the accuracy of current detection.

[0060] In one embodiment, Figure 2As shown, the self-excited oscillation fluxgate current sensor 102 includes: a small current fluxgate current sensor 1021, a first magnetic field signal generating module 1022, a large current fluxgate current sensor 1023, a second magnetic field signal generating module 1024, a switch tube 1025 and a first comparator 1026.

[0061] The first pole of the switch tube 1025 is connected to the output end of the small current fluxgate current sensor 1021 , and the second pole of the switch tube 1025 is connected to the input end of the first magnetic field signal generating module 1022 .

[0062] The input end of the first comparator 1026 is connected to the output end of the large current fluxgate current sensor 1023, the reference end of the first comparator 1026 is used to access the reference voltage, the output end of the first comparator 1026 is connected to the third pole of the switch tube 1025, and the first comparator 1026 is used to:

[0063] When the output voltage of the high current fluxgate current sensor 1023 is greater than the reference voltage (such as Figure 2 In the case of a REF signal as shown in FIG. 1 , the switch tube 1025 is turned off so that the large current fluxgate current sensor 1023 outputs a voltage to the second magnetic field signal generating module 1024.

[0064] When the output voltage of the large current fluxgate current sensor 1023 is less than or equal to the reference voltage, the switch tube 1025 is turned on to make the small current fluxgate current sensor 1021 output voltage to the first magnetic field signal generating module 1022 .

[0065] When the output voltage of the large current fluxgate current sensor 1023 is greater than the reference voltage, the first comparator 1026 outputs the first level to the switch tube 1025, and the switch tube 1025 is turned off at the first level, so that the output voltage of the large current fluxgate current sensor 1023 cannot be output to the first magnetic field signal generating module 1022 through the switch tube 1025. At this time, the output voltage of the large current fluxgate current sensor 1023 can only be output to the second magnetic field signal generating module 1024, and output to the magnetic integrator 104 via the second magnetic field signal generating module 1024.

[0066] When the output voltage of the large current fluxgate current sensor 1023 is less than or equal to the reference voltage, the first comparator 1026 outputs the second level to the switch tube 1025, and the switch tube 1025 is turned on at the second level. At this time, the circuit between the small current fluxgate current sensor 1021 and the first magnetic field signal generating module 1022 is turned on, and the small current fluxgate current sensor 1021 can output a voltage to the first magnetic field signal generating module 1022, and output it to the magnetic integrator 104 via the first magnetic field signal generating module 1022.

[0067] The output voltage of the large current fluxgate current sensor 1023 is used to characterize the large current flux detection signal, and the output voltage of the small current fluxgate current sensor 1021 is used to characterize the small current flux detection signal.

[0068] The first level may be a high level, and correspondingly, the second level is a low level; of course, the first level may also be a low level, and correspondingly, the second level is a high level.

[0069] In one embodiment, Figure 2 As shown, the circuit structure of the large current fluxgate current sensor 1023 and the small current fluxgate current sensor 1021 is the same, and the large current fluxgate current sensor 1023 includes: a first induction coil (such as Figure 2 N2 shown), the first resistor (such as Figure 2 R4 shown), the second comparator (such as Figure 2 A1 shown) and a second resistor (as Figure 2 R1 shown).

[0070] The first induction coil is used to sense the magnetic field generated by the energized wire.

[0071] A first end of the first resistor is connected to a first end of the first induction coil, and a second end of the first resistor is grounded.

[0072] The first input terminal of the second comparator is connected to the first terminal of the first resistor, the second input terminal of the second comparator is connected to the second terminal of the first induction coil, and the output terminal of the second comparator is connected to the first terminal of the first induction coil.

[0073] A first end of the second resistor is connected to the second end of the first induction coil, and a second end of the second resistor is grounded.

[0074] When the second comparator outputs a high level, the fixed voltage on the first end of the first induction coil is the divided voltage on the first resistor. At this time, the first induction coil starts to charge as an inductor. Since the voltage on the second end of the first induction coil is lower than the voltage on the first end of the first induction coil, the second comparator still outputs a high level.

[0075] When the first induction coil is fully charged, the inductance of the first induction coil decreases, which can be regarded as a state close to a short circuit, causing the voltage at the second end of the first induction coil to increase instantly, exceeding the voltage at the first end of the first induction coil. At this time, the second comparator outputs a low level.

[0076] The alternating output of the high level and the low level of the second comparator can continuously charge and discharge the first induction coil, so that the first induction coil oscillates. In the case of zero magnetic flux, the oscillation duty cycle of the first induction coil is 50%. When the magnetic flux changes, the oscillation duty cycle of the first induction coil increases or decreases accordingly.

[0077] Correspondingly, the low current fluxgate current sensor 1021 includes: a first induction coil (such as Figure 2 N5 shown), the first resistor (such as Figure 2 R7 shown), the second comparator (as Figure 2 A2 shown) and a second resistor (as Figure 2 R6 shown).

[0078] The working principle of the small current fluxgate current sensor 1021 is consistent with the working principle of the large current fluxgate current sensor 1023 , and will not be described in detail here.

[0079] It should be noted that the device model of the small current fluxgate current sensor 1021 is different from the device model of the large current fluxgate current sensor 1023. The small current fluxgate current sensor 1021 uses a low-inductance magnetic core and a device sensitive to a small current magnetic flux, thereby improving the sensitivity of small current magnetic field induction. Correspondingly, the large current fluxgate current sensor 1023 uses a high-inductance magnetic core and a device sensitive to a large current magnetic flux, thereby improving the sensitivity of large current magnetic field induction.

[0080] In one embodiment, Figure 2 As shown, the large current fluxgate current sensor 1023 further includes: a second induction coil (such as Figure 2 N1 shown).

[0081] A first end of the second induction coil is connected to the output end of the second comparator, and a second end of the second induction coil is grounded.

[0082] The directions of the same-named ends of the first induction coil and the second induction coil are opposite, and the number of winding turns of the first induction coil and the second induction coil are the same.

[0083] The directions of the like-named ends of the first induction coil and the second induction coil are opposite, so the second induction coil can generate an oscillation waveform opposite to that of the first induction coil; and the first induction coil and the second induction coil have the same number of turns, so the oscillation waveform generated by the second induction coil can offset the oscillation waveform generated by the first induction coil, thereby reducing external radiation interference and noise, and improving the detection accuracy of the zero-flux closed-loop circuit 10.

[0084] Correspondingly, the low current fluxgate current sensor 1021 further includes: a second induction coil (such as Figure 2N6 shown).

[0085] The first induction coil and the second induction coil comprise a magnetic core, and the material of the magnetic core may be selected from a magnetic core material with high magnetic permeability, low coercive force and small temperature coefficient, such as a cobalt-based amorphous alloy.

[0086] The probe of the self-excited oscillation fluxgate current sensor 102 can be arranged between two magnetic cores located at the first induction coil and the second induction coil to detect the change of the magnetic field, thereby reducing the uneven distribution of the magnetic field caused by the asymmetric structure and reducing measurement errors and noise.

[0087] In one embodiment, Figure 2 As shown, the high current fluxgate current sensor 1023 further includes: a third resistor (such as Figure 2 R3 shown), the fourth resistor (such as Figure 2 R5) and the fifth resistor (as shown Figure 2 R11 shown).

[0088] The third resistor is connected in series between the first end of the first induction coil and the first input end of the second comparator.

[0089] The fourth resistor is connected in series between the first end of the first induction coil and the output end of the second comparator.

[0090] One end of the fifth resistor is connected to the second end of the second induction coil, and the other end of the fifth resistor is grounded.

[0091] The third resistor, the fourth resistor and the fifth resistor are used for current limiting to ensure that the small current fluxgate current sensor 1021 is in a normal operating state.

[0092] Correspondingly, the low current fluxgate current sensor 1021 further includes: a third resistor (such as Figure 2 R8 shown), the fourth resistor (such as Figure 2 R9) and the fifth resistor (as Figure 2 R10 shown).

[0093] In one embodiment, Figure 3 As shown, the feedback circuit 106 includes: an amplification module 1062 , an analog-to-digital conversion module 1064 and a control circuit 1066 .

[0094] The input end of the amplification module 1062 is connected to the output end of the magnetic integrator 104 .

[0095] An input end of the analog-to-digital conversion module 1064 is connected to an output end of the amplification module 1062 .

[0096] An input end of the control circuit 1066 is connected to an output end of the analog-to-digital conversion module 1064 , and an output end of the control circuit 1066 is connected to the self-excited oscillation fluxgate current sensor 102 .

[0097] The amplification module 1062 is used to amplify the voltage signal output by the magnetic integrator 104 to prepare for subsequent signal analysis and determination of the current.

[0098] The analog-to-digital conversion module 1064 converts the output signal of the amplification module 1062 into a digital signal, thereby increasing the stability of the signal, reducing the distortion of the signal, and improving the accuracy of the final current detection result.

[0099] When the analog-to-digital conversion module 1064 is enabled and receives the output signal of the analog-to-digital conversion module 1064 , the control circuit 1066 outputs a control signal to the self-excited oscillation fluxgate current sensor 102 to keep the magnetic flux passing through the fluxgate of the self-excited oscillation fluxgate current sensor 102 near the zero flux point.

[0100] In one embodiment, Figure 4 As shown, the zero flux closed-loop circuit 10 further includes: a voltage-stabilized power supply 108 .

[0101] The voltage-stabilized power supply 108 is used to provide operating voltages for the magnetic integrator 104 and the feedback circuit 106 .

[0102] The voltage-stabilized power supply 108 can provide a stable operating voltage for the magnetic integrator 104 and the feedback circuit 106 , thereby reducing the fluctuation of the zero-flux closed-loop circuit 10 and improving the detection accuracy.

[0103] In one embodiment, Figure 4 As shown, the above-mentioned voltage-stabilized power supply 108 includes: a power module 1081, and an operational amplifier 1082, a voltage source 1083 and a switch module 1084 which are sequentially connected in series between the output end and the controlled end of the power module 1081.

[0104] The power supply module 1081 outputs a signal to the operational amplifier 1082 to amplify its output signal. The operational amplifier 1082 outputs its output signal to the voltage source 1083. When the voltage source 1083 has a signal output, the switch module 1084 is turned on so that the power supply module 1081 outputs a stable operating voltage to the magnetic integrator 104 and the feedback circuit 106.

[0105] In one embodiment, Figure 4 As shown, the above-mentioned voltage-stabilized power supply 108 also includes: a rectification and filtering module 1085.

[0106] The rectifier and filter module 1085 is connected in series between the operational amplifier 1082 and the voltage source 1083 .

[0107] The output signal of the operational amplifier 1082 can improve its stability and smoothness after passing through the rectifier and filter module 1085 , thereby outputting a stable signal to the voltage source 1083 and reducing the output fluctuation of the regulated power supply 108 .

[0108] The rectification and filtering module 1085 can be implemented based on capacitors and inductors, or other components or modules such as a rectifier bridge.

[0109] In one embodiment, Figure 4 As shown, the above-mentioned voltage-stabilized power supply 108 also includes: a voltage dividing module 1086.

[0110] The voltage divider module 1086 is connected in series between the operational amplifier 1082 and the rectifier and filter module 1085 .

[0111] By setting the voltage divider module 1086, the signal output by the voltage regulator 108 can be adapted to the actual working conditions of the magnetic integrator 104 and the feedback circuit 106 in the actual application scenario, thereby preventing the magnetic integrator 104 and the feedback circuit 106 from operating at too high or too low an operating voltage, thereby improving the safety and stability of the zero flux closed-loop circuit 10.

[0112] For example, the voltage dividing module 1086 may include at least one resistor connected in series.

[0113] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0114] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0115] 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 zero flux closed-loop circuit, characterized in that: include: A self-excited oscillation fluxgate current sensor, wherein a current-carrying wire passes through a fluxgate of the self-excited oscillation fluxgate current sensor; the self-excited oscillation fluxgate current sensor is used to generate an excitation current to sense the current of the current-carrying wire, and the self-excited oscillation fluxgate current sensor generates a magnetic field signal under the action of the excitation current; A magnetic integrator, wherein an input end of the magnetic integrator is connected to an output end of the self-excited oscillation fluxgate current sensor, and the magnetic integrator is used to generate a voltage signal according to the magnetic field signal; A feedback circuit, wherein the output end of the feedback circuit is connected to the self-excited oscillation fluxgate current sensor, and the input end of the feedback circuit is connected to the magnetic integrator; the feedback circuit is used to generate a feedback signal according to the magnetic field strength corresponding to the voltage signal and transmit the feedback signal to the self-excited oscillation fluxgate current sensor, so that the self-excited oscillation fluxgate current sensor adjusts the excitation current so that the magnetic flux passing through the fluxgate is maintained within a preset range; The preset range is a magnetic field range with a zero magnetic flux point as the center and a floating preset value.

2. The zero flux closed-loop circuit according to claim 1, characterized in that: The self-excited oscillation fluxgate current sensor comprises: a small current fluxgate current sensor, a first magnetic field signal generating module, a large current fluxgate current sensor, a second magnetic field signal generating module, a switch tube and a first comparator; Wherein, the first pole of the switch tube is connected to the output end of the small current fluxgate current sensor, and the second pole of the switch tube is connected to the input end of the first magnetic field signal generating module; The input end of the first comparator is connected to the output end of the large current fluxgate current sensor, the reference end of the first comparator is used to access the reference voltage, the output end of the first comparator is connected to the third pole of the switch tube, and the first comparator is used to: When the output voltage of the high-current fluxgate current sensor is greater than the reference voltage, turning off the switch tube so that the high-current fluxgate current sensor outputs a voltage to the second magnetic field signal generating module; When the output voltage of the large current fluxgate current sensor is less than or equal to the reference voltage, the switch tube is turned on to make the small current fluxgate current sensor output voltage to the first magnetic field signal generating module.

3. The zero flux closed-loop circuit according to claim 2, characterized in that: The circuit structure of the large current fluxgate current sensor and the small current fluxgate current sensor is the same, and the large current fluxgate current sensor includes: a first induction coil, the first induction coil being used to sense the magnetic field generated by the energized wire; a first resistor, wherein a first end of the first resistor is connected to a first end of the first induction coil, and a second end of the first resistor is grounded; a second comparator, wherein a first input terminal of the second comparator is connected to a first terminal of the first resistor, a second input terminal of the second comparator is connected to a second terminal of the first induction coil, and an output terminal of the second comparator is connected to a first terminal of the first induction coil; A second resistor, wherein a first end of the second resistor is connected to the second end of the first induction coil, and a second end of the second resistor is grounded.

4. The zero flux closed-loop circuit according to claim 3, characterized in that: The high current fluxgate current sensor also includes: a second induction coil, wherein a first end of the second induction coil is connected to an output end of the second comparator, and a second end of the second induction coil is grounded; The directions of the same-named ends of the first induction coil and the second induction coil are opposite, and the number of winding turns of the first induction coil and the second induction coil are the same.

5. The zero flux closed-loop circuit according to claim 4, characterized in that: The high current fluxgate current sensor also includes: a third resistor, the third resistor being connected in series between the first end of the first induction coil and the first input end of the second comparator; a fourth resistor, the fourth resistor being connected in series between the first end of the first induction coil and the output end of the second comparator; a fifth resistor, one end of the fifth resistor being connected to the second end of the second induction coil, and the other end of the fifth resistor being grounded.

6. The zero flux closed-loop circuit according to claim 1, characterized in that: The feedback circuit comprises: an amplification module, wherein an input end of the amplification module is connected to an output end of the magnetic integrator; An analog-to-digital conversion module, the input end of which is connected to the output end of the amplification module; A control circuit, wherein the input end of the control circuit is connected to the output end of the analog-to-digital conversion module, and the output end of the control circuit is connected to the self-excited oscillation fluxgate current sensor.

7. The zero flux closed-loop circuit according to claim 1, characterized in that: Also includes: A voltage-stabilized power supply is used to provide operating voltages for the magnetic integrator and the feedback circuit respectively.

8. The zero flux closed-loop circuit according to claim 7, characterized in that: The voltage-stabilized power supply comprises: Power module; An operational amplifier, a voltage source and a switch module are sequentially connected in series between the output end and the controlled end of the power module.

9. The zero-flux closed-loop circuit according to claim 8, characterized in that: The voltage-stabilized power supply also includes: A rectifier and filter module is connected in series between the operational amplifier and the voltage source.

10. The zero flux closed-loop circuit according to claim 9, characterized in that: The voltage-stabilized power supply also includes: A voltage divider module is connected in series between the operational amplifier and the rectifier and filter module.

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