Zero flux closed loop circuit

Abstract

The application relates to a zero-flux closed-loop circuit, which comprises a self-oscillating fluxgate current sensor, a magnetic integrator and a feedback circuit; wherein the self-oscillating 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, the feedback circuit can generate a feedback signal according to the corresponding magnetic field intensity of the voltage signal, and the feedback signal acts on the self-oscillating fluxgate current sensor, so that the self-oscillating fluxgate current sensor adjusts the excitation current, thereby ensuring that the magnetic flux of a fluxgate through the self-oscillating fluxgate current sensor is kept near a zero-flux point. Therefore, the zero-flux closed-loop circuit can effectively reduce the influence of noise and the distortion degree of a signal when detecting the current of a current-carrying wire in a zero-flux environment, thereby improving the precision of current detection.

Description

Technical Field

[0001] This application relates to the field of zero flux circuit technology, and in particular to a zero flux closed-loop circuit. Background Technology

[0002] In modern life, there are various circuit systems. Detecting the current in these circuit systems ensures they are functioning properly. The traditional method is to use a self-excited fluxgate current sensor to detect the current in the circuit system. However, the measurement accuracy of self-excited fluxgate current sensors is low when subjected to external magnetic field interference. Summary of the Invention

[0003] Therefore, 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 fluxgate current sensor has a fluxgate through which a current-carrying wire passes; the self-excited fluxgate current sensor is used to generate an excitation current to sense the current carrying in the current-carrying wire, and generates a magnetic field signal under the action of the excitation current.

[0006] The magnetic integrator is connected to the output of the self-excited oscillating fluxgate current sensor. The magnetic integrator is used to generate a voltage signal based on the magnetic field signal.

[0007] The feedback circuit has its output connected to a self-excited oscillating fluxgate current sensor and its input connected to a magnetic integrator. The feedback circuit generates a feedback signal based on the magnetic field strength corresponding to the voltage signal and transmits it to the self-excited oscillating fluxgate current sensor so that the self-excited oscillating fluxgate current sensor adjusts the excitation current so that the magnetic flux through the fluxgate remains within a preset range.

[0008] The preset range is the magnetic field range centered on the zero flux point, with a preset value fluctuating up and down.

[0009] In one embodiment, the self-excited oscillating fluxgate current sensor includes: a small current fluxgate current sensor, a first magnetic field signal generation module, a large current fluxgate current sensor, a second magnetic field signal generation module, a switching transistor, and a first comparator.

[0010] The first terminal of the switching transistor is connected to the output terminal of the small current fluxgate current sensor, and the second terminal of the switching transistor is connected to the input terminal of the first magnetic field signal generation module.

[0011] The input of the first comparator is connected to the output of the high-current fluxgate current sensor. The reference terminal of the first comparator is used to connect to a reference voltage. The output of the first comparator is connected to the third terminal of the switching transistor. The first comparator is used for:

[0012] When the output voltage of the high-current fluxgate current sensor is greater than the reference voltage, the switching transistor is turned off so that the output voltage of the high-current fluxgate current sensor is supplied to the second magnetic field signal generation module.

[0013] When the output voltage of the high-current fluxgate current sensor is less than or equal to the reference voltage, the switching transistor is turned on so that the output voltage of the low-current fluxgate current sensor is supplied to the first magnetic field signal generation module.

[0014] In one embodiment, the circuit structure of the high-current fluxgate current sensor and the low-current fluxgate current sensor are the same, and the high-current fluxgate current sensor includes:

[0015] The first induction coil is used to sense the magnetic field generated by the current-carrying conductor.

[0016] The first resistor has its first end connected to the first end of the first induction coil and its second end grounded.

[0017] The second comparator has its first input terminal connected to the first terminal of the first resistor, its second input terminal connected to the second terminal of the first induction coil, and its output terminal connected to the first terminal of the first induction coil.

[0018] The second resistor has its first end connected to the second end of the first induction coil, and its second end grounded.

[0019] In one embodiment, the above-mentioned high-current fluxgate current sensor further includes:

[0020] The second induction coil has its first end connected to the output of the second comparator and its second end grounded.

[0021] The first and second induction coils have opposite directions at their corresponding ends, and the first and second induction coils have the same number of turns.

[0022] In one embodiment, the above-mentioned high-current fluxgate current sensor further includes:

[0023] 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.

[0024] The fourth resistor is connected in series between the first end of the first induction coil and the output of the second comparator.

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

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

[0027] An amplifier module, the input of which is connected to the output of a magnetic integrator;

[0028] The analog-to-digital converter module has its input connected to the output of the amplifier module.

[0029] The control circuit has its input terminal connected to the output terminal of the analog-to-digital converter module, and its output terminal connected to the self-excited oscillating fluxgate current sensor.

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

[0031] A regulated power supply is used to provide operating voltage for the magnetic integrator and the feedback circuit, respectively.

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

[0033] Power module;

[0034] An operational amplifier, a voltage source, and a switching module are connected in series between the output and controlled terminals of the power supply module.

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

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

[0039] The aforementioned zero-flux closed-loop circuit includes a self-excited oscillating fluxgate current sensor, a magnetic integrator, and a feedback circuit. The self-excited oscillating fluxgate current sensor generates a magnetic field signal under the action of an excitation current. The magnetic integrator generates a corresponding voltage signal based on this magnetic field signal. The feedback circuit generates a feedback signal based on the magnetic field strength corresponding to the voltage signal, which is then applied to the self-excited oscillating fluxgate current sensor. This causes the sensor to adjust the excitation current, thereby ensuring that the flux through the fluxgate of the self-excited oscillating fluxgate current sensor remains near the zero flux point. Therefore, this zero-flux closed-loop circuit can effectively reduce the influence of noise and the degree of signal distortion when detecting the current in a current-carrying conductor in a zero-flux environment, thus improving the accuracy of current detection. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is one of the structural block diagrams of a zero-flux closed-loop circuit according to an embodiment;

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

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

[0044] Figure 4 This is the third block diagram of a zero-flux closed-loop circuit according to one embodiment. Detailed Implementation

[0045] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0047] It is understood that the terms "first," "second," etc., used in this application may be used to describe various elements herein, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first magnetic field signal generating module may be referred to as a second magnetic field signal generating module, and similarly, a second magnetic field signal generating module may be referred to as a 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 is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0049] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0050] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude 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, such as Figure 1 As shown, a zero-flux closed-loop circuit 10 is provided, including: a self-excited oscillating fluxgate current sensor 102, a magnetic integrator 104, and a feedback circuit 106.

[0052] In the self-excited oscillating fluxgate current sensor 102, a current-carrying wire passes through the fluxgate; the self-excited oscillating fluxgate current sensor 102 is used to generate an excitation current to sense the current carrying in the current-carrying wire, and the self-excited oscillating fluxgate current sensor 102 generates a magnetic field signal under the action of the excitation current.

[0053] The input terminal of the magnetic integrator 104 is connected to the output terminal of the self-excited oscillating fluxgate current sensor 102. The magnetic integrator 104 is used to generate a voltage signal based on the magnetic field signal.

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

[0055] The preset range is a magnetic field range centered on the zero flux point, fluctuating up and down by a preset value. The smaller the preset value, the closer the magnetic flux passing through the fluxgate is to the zero flux point, and the more accurate the result obtained from detecting the current flow at a point closer to the zero flux point.

[0056] The self-excited oscillating fluxgate current sensor 102 includes a built-in oscillation circuit that generates an excitation current. The magnetic field generated by this excitation current and the magnetic field generated by the current flowing through it are spatially superimposed to determine a magnetic field signal. Since the self-excited oscillating fluxgate current sensor 102 can operate using the magnetic field generated by the current flowing through it without needing an external power supply, its operating state depends on the magnitude and direction of the current flowing through it. The magnetic field signal is positively correlated with the current flowing through it.

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

[0058] Feedback circuit 106 generates a feedback signal based on the magnetic field strength corresponding to the voltage signal generated by magnetic integrator 104, and transmits the feedback signal to self-excited oscillating fluxgate current sensor 102. This allows self-excited oscillating fluxgate current sensor 102 to adjust 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-carrying current. This ensures that the magnetic flux of the fluxgate through the self-excited oscillating fluxgate current sensor 102 remains near the zero flux point, thereby realizing the detection of the current-carrying current of the current-carrying conductor in a zero flux environment.

[0059] The aforementioned zero-flux closed-loop circuit 10 includes a self-excited oscillating fluxgate current sensor 102, a magnetic integrator 104, and a feedback circuit 106. The self-excited oscillating fluxgate current sensor 102 generates a magnetic field signal under the action of an excitation current. The magnetic integrator 104 generates a corresponding voltage signal based on this magnetic field signal. The feedback circuit 106 generates a feedback signal based on the magnetic field strength corresponding to the voltage signal and applies it to the self-excited oscillating fluxgate current sensor 102. This causes the self-excited oscillating fluxgate current sensor 102 to adjust the excitation current, thereby ensuring that the flux through the fluxgate of the self-excited oscillating fluxgate current sensor 102 remains near the zero flux point. Therefore, this zero-flux closed-loop circuit 10 can detect the current flowing through a current-carrying conductor in a zero-flux environment, effectively reducing the influence of noise and the degree of signal distortion, thereby improving the accuracy of current detection.

[0060] In one embodiment, such as Figure 2As shown, the self-excited oscillating fluxgate current sensor 102 includes: a small current fluxgate current sensor 1021, a first magnetic field signal generation module 1022, a large current fluxgate current sensor 1023, a second magnetic field signal generation module 1024, a switching transistor 1025, and a first comparator 1026.

[0061] The first terminal of the switching transistor 1025 is connected to the output terminal of the small current fluxgate current sensor 1021, and the second terminal of the switching transistor 1025 is connected to the input terminal of the first magnetic field signal generation module 1022.

[0062] The input terminal of the first comparator 1026 is connected to the output terminal of the high-current fluxgate current sensor 1023. The reference terminal of the first comparator 1026 is used to connect a reference voltage. The output terminal of the first comparator 1026 is connected to the third terminal of the switching transistor 1025. The first comparator 1026 is used for:

[0063] The output voltage of the high-current fluxgate current sensor 1023 is greater than the reference voltage (e.g.) Figure 2 In the case of the REF signal shown, the switch 1025 is turned off so that the high current fluxgate current sensor 1023 outputs voltage to the second magnetic field signal generation module 1024.

[0064] When the output voltage of the high-current fluxgate current sensor 1023 is less than or equal to the reference voltage, the switch 1025 is turned on so that the output voltage of the low-current fluxgate current sensor 1021 is sent to the first magnetic field signal generation module 1022.

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

[0066] When the output voltage of the high-current fluxgate current sensor 1023 is less than or equal to the reference voltage, the first comparator 1026 outputs a second level to the switching transistor 1025, and the switching transistor 1025 is turned on under the second level. At this time, the circuit between the low-current fluxgate current sensor 1021 and the first magnetic field signal generation module 1022 is turned on, and the low-current fluxgate current sensor 1021 can output a voltage to the first magnetic field signal generation module 1022, and then output it to the magnetic integrator 104 via the first magnetic field signal generation module 1022.

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

[0068] In this context, the first level can be a high level, and the corresponding second level is a low level; of course, the first level can also be a low level, and the corresponding second level is a high level.

[0069] In one embodiment, such as Figure 2 As shown, the circuit structures of the high-current fluxgate current sensor 1023 and the low-current fluxgate current sensor 1021 are the same, and the high-current fluxgate current sensor 1023 includes: a first induction coil (such as...) Figure 2 N2 as shown), first resistor (as shown) Figure 2 R4 (as shown), the second comparator (as shown) Figure 2 As shown in A1) and the second resistor (as shown in A1) Figure 2 R1 (as shown).

[0070] The first induction coil is used to sense the magnetic field generated by the current-carrying conductor.

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

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

[0075] When the first induction coil is fully charged, its inductive reactance decreases, which can be considered as an approximate short circuit. This causes the voltage at the second terminal of the first induction coil to increase instantaneously, exceeding the voltage at the first terminal. At this time, the second comparator outputs a low level.

[0076] The alternating high and low outputs of the second comparator enable continuous charging and discharging of the first induction coil, thereby causing it to oscillate. With zero magnetic flux, the oscillation duty cycle of the first induction coil is 50%. As the magnetic flux changes, the oscillation duty cycle of the first induction coil increases or decreases accordingly.

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

[0078] The working principle of the small current fluxgate current sensor 1021 is the same as that of the large current fluxgate current sensor 1023, and will not be repeated here.

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

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

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

[0082] The first and second induction coils have opposite directions at their corresponding ends, and the first and second induction coils have the same number of turns.

[0083] The corresponding terminals of the first and second induction coils are in opposite directions. Therefore, the second induction coil can generate an oscillation waveform opposite to that of the first induction coil. Since the number of turns of the first and second induction coils is the same, the oscillation waveform generated by the second induction coil can cancel each other out with 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 small current fluxgate current sensor 1021 also includes: a second induction coil (such as...) Figure 2N6 (as shown).

[0085] The first and second induction coils mentioned above include magnetic cores. The magnetic core material can be selected from materials such as cobalt-based amorphous alloys, which have high permeability, low coercivity and small temperature coefficient.

[0086] The probe of the self-excited oscillating fluxgate current sensor 102 can be set between the two magnetic cores of the first induction coil and the second induction coil to detect changes in the magnetic field, thereby reducing the uneven distribution of the magnetic field caused by structural asymmetry and reducing measurement errors and noise.

[0087] In one embodiment, such as Figure 2 As shown, the high-current fluxgate current sensor 1023 also includes: a third resistor (such as...) Figure 2 R3 as shown), the fourth resistor (as shown) Figure 2 R5 (as shown) and the fifth resistor (as shown) Figure 2 R11 (as 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 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, fourth, and fifth resistors mentioned above are used for current limiting to ensure that the small current fluxgate current sensor 1021 is in normal operating condition.

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

[0093] In one embodiment, such as 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 terminal of the amplification module 1062 is connected to the output terminal of the magnetic integrator 104.

[0095] The input terminal of the analog-to-digital converter module 1064 is connected to the output terminal of the amplifier module 1062.

[0096] The input terminal of the control circuit 1066 is connected to the output terminal of the analog-to-digital converter module 1064, and the output terminal of the control circuit 1066 is connected to the self-excited oscillating fluxgate current sensor 102.

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

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

[0099] When the analog-to-digital converter module 1064 is enabled and the output signal of the analog-to-digital converter module 1064 is received, the control circuit 1066 outputs a control signal to the self-excited oscillating fluxgate current sensor 102, so that the flux of the fluxgate through the self-excited oscillating fluxgate current sensor 102 is kept near the zero flux point.

[0100] In one embodiment, such as Figure 4 As shown, the above-mentioned zero-flux closed-loop circuit 10 also includes a regulated power supply 108.

[0101] The regulated power supply 108 is used to provide operating voltages for the magnetic integrator 104 and the feedback circuit 106, respectively.

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

[0103] In one embodiment, such as Figure 4 As shown, the above-mentioned regulated power supply 108 includes: a power supply module 1081, and an operational amplifier 1082, a voltage source 1083, and a switching module 1084 connected in series between the output terminal and the controlled terminal of the power supply module 1081.

[0104] The power 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 module 1081 outputs a stable operating voltage to the magnetic integrator 104 and the feedback circuit 106.

[0105] In one embodiment, such as Figure 4 As shown, the above-mentioned regulated power supply 108 also includes a rectifier and filter 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 be improved in terms of 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 rectifier and filter module 1085 can be implemented based on capacitors and inductors, or other components or modules such as rectifier bridges.

[0109] In one embodiment, such as Figure 4 As shown, the above-mentioned regulated power supply 108 also includes a voltage divider module 1086.

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

[0111] By setting the voltage divider module 1086, the signal output by the regulated power supply 108 can be adapted to the actual operating conditions of the magnetic integrator 104 and the feedback circuit 106 in the actual application scenario, thereby avoiding the magnetic integrator 104 and the feedback circuit 106 from operating under excessively high or low operating voltages, and improving the safety and stability of the zero flux closed-loop circuit 10.

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

[0113] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0114] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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.

[0115] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A zero-flux closed-loop circuit, characterized in that, include: A self-excited fluxgate current sensor has a fluxgate through which a current-carrying wire passes; the self-excited fluxgate current sensor is used to generate an excitation current to sense the current-carrying wire, and the self-excited fluxgate current sensor generates a magnetic field signal under the action of the excitation current. A magnetic integrator, the input of which is connected to the output of the self-excited oscillating fluxgate current sensor, is used to generate a voltage signal based on the magnetic field signal. A feedback circuit is provided, the output of which is connected to the self-excited oscillating fluxgate current sensor, and the input of which is connected to the magnetic integrator. The feedback circuit is used to generate a feedback signal based on the magnetic field strength corresponding to the voltage signal and transmit it to the self-excited oscillating fluxgate current sensor so that the self-excited oscillating fluxgate current sensor adjusts the excitation current so that the magnetic flux through the fluxgate is kept within a preset range. The preset range is a magnetic field range centered on the zero flux point, with a preset value fluctuating up and down.

2. The zero-flux closed-loop circuit according to claim 1, characterized in that, The self-excited oscillating fluxgate current sensor includes: a small current fluxgate current sensor, a first magnetic field signal generation module, a large current fluxgate current sensor, a second magnetic field signal generation module, a switching transistor, and a first comparator. The first terminal of the switching transistor is connected to the output terminal of the small current fluxgate current sensor, and the second terminal of the switching transistor is connected to the input terminal of the first magnetic field signal generation module. The input terminal of the first comparator is connected to the output terminal of the high-current fluxgate current sensor. The reference terminal of the first comparator is used to connect to a reference voltage. The output terminal of the first comparator is connected to the third terminal of the switching transistor. The first comparator is used for: When the output voltage of the high-current fluxgate current sensor is greater than the reference voltage, the switching transistor is turned off so that the output voltage of the high-current fluxgate current sensor is sent to the second magnetic field signal generation module. When the output voltage of the high-current fluxgate current sensor is less than or equal to the reference voltage, the switching transistor is turned on so that the output voltage of the low-current fluxgate current sensor is sent to the first magnetic field signal generation module.

3. The zero-flux closed-loop circuit according to claim 2, characterized in that, The high-current fluxgate current sensor and the low-current fluxgate current sensor have the same circuit structure, and the high-current fluxgate current sensor includes: A first induction coil is used to sense the magnetic field generated by the current-carrying conductor. A first resistor, the first end of which is connected to the first end of the first induction coil, and the second end of which is grounded; A second comparator has its first input terminal connected to the first terminal of the first resistor, its second input terminal connected to the second terminal of the first induction coil, and its output terminal connected to the first terminal of the first induction coil. The second resistor has its first end connected to the second end of the first induction coil, and its second end 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, the first end of which is connected to the output of the second comparator, and the second end of which is grounded; Wherein, the corresponding ends of the first induction coil and the second induction coil are in opposite directions, and the first induction coil and the second induction coil have the same number of turns.

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

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

7. The zero-flux closed-loop circuit according to claim 1, characterized in that, Also includes: A regulated power supply is provided 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 regulated power supply includes: Power module; An operational amplifier, a voltage source, and a switching module are connected in series between the output terminal and the controlled terminal of the power module.

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

Images