Current detection circuit and current detection device

Abstract

The invention relates to a current detection circuit and current detection equipment. The circuit comprises a control module and a probe. The probe comprises a fluxgate which comprises two first induction coils, two first feedback coils, two first magnetic cores and two excitation coils which are connected in series; the two excitation coils are wound on the two first magnetic cores respectively, the two first induction coils are wound on the two first magnetic cores respectively, and the two first feedback coils are wound on the two first magnetic cores respectively; the mutual inductance module comprises a second induction coil, a second feedback coil and a second magnetic core; the second induction coil and the second feedback coil are both wound on the second magnetic core; the first induction coil and the second induction coil are wound in the same direction, and the first feedback coil and the second feedback coil are wound in the same direction; the second induction coil in each probe is connected with each first induction coil in series; the second feedback coil is connected in series with each first feedback coil; the control module determines a feedback signal according to the acquired sensing signal. The bandwidth of the probe can be improved.

Description

Technical Field

[0001] This application relates to the field of electromagnetic induction technology, and in particular to a current detection circuit and a current detection device. Background Technology

[0002] With the development of technology, current sensing technology is playing an increasingly important role in many fields (such as power monitoring, battery management, and automotive electronic systems), but existing current sensing circuits have limitations in measurement bandwidth. Summary of the Invention

[0003] This application provides a current detection circuit and a current detection device, which can improve the detection current bandwidth of the current detection device.

[0004] The first aspect of this application provides a current detection circuit, comprising: a control module and m probes, where m is greater than or equal to 1; each probe includes:

[0005] A fluxgate includes two first induction coils, two first feedback coils, two first magnetic cores, and two excitation coils connected in series; the two excitation coils are wound in opposite directions around the two first magnetic cores, the two first induction coils are wound in the same direction around the two first magnetic cores, and the two first feedback coils are wound in the same direction around the two first magnetic cores.

[0006] The mutual inductance module includes a second induction coil, a second feedback coil, and a second magnetic core; both the second induction coil and the second feedback coil are wound around the second magnetic core; wherein the first induction coil and the second induction coil are wound in the same direction, and the first feedback coil and the second feedback coil are wound in the same direction.

[0007] In each of the probes, the second induction coil and each of the first induction coils are connected in series to form an induction closed loop; the second feedback coil and each of the first feedback coils are connected in series.

[0008] The control module is used to acquire the induction signal of the induction closed loop and determine the feedback signal based on the induction signal to control the feedback current of the feedback coil.

[0009] In some embodiments, when m equals 1, the control module includes a first signal processing unit, a second signal processing unit, and a feedback unit;

[0010] The first signal processing unit is connected to the two ends of the series connection of the two first induction coils through the second signal processing unit. The first signal processing unit is also connected to the two ends of the series connection of the two first feedback coils and the second feedback coil through the feedback unit.

[0011] The second signal processing unit is used to determine a first target signal based on the acquired sensing signal; the first signal processing unit demodulates the first target signal to determine a modulation signal; and the feedback unit determines the feedback signal based on the modulation signal.

[0012] In some embodiments, when m is greater than 1, the control module includes a first signal processing unit, a first selection unit, a second selection unit, a judgment unit, m second signal processing units and m feedback units, and each probe corresponds to a second signal processing unit and a feedback unit respectively;

[0013] The first selection unit is connected to each of the second signal processing units, and each of the second signal processing units is connected to the two ends of the series connection of the two first induction coils in the corresponding probe.

[0014] The first selection unit is also connected to the second selection unit in sequence through the first signal processing unit and the judgment unit. The second selection unit is also connected to each of the feedback units. Each feedback unit is connected to the two ends of the three coils connected in series: the two first feedback coils and the second feedback coil in the corresponding probe.

[0015] In some embodiments, the second signal processing unit is configured to determine a first target signal based on the acquired sensing signal; the first signal processing unit performs demodulation based on the first target signal to determine a modulation signal;

[0016] The judgment unit is configured to determine a judgment signal based on the modulation signal, and transmit the judgment signal carrying the target probe information to the first selection unit and the second selection unit respectively, so that the first selection unit connects to the target second signal processing unit corresponding to the target probe information and disconnects from the second signal processing unit corresponding to the non-target probe information based on the judgment signal, and the second selection unit connects to the target feedback unit corresponding to the target probe information based on the judgment signal.

[0017] The first selection unit is further configured to transmit the judgment signal carrying feedback adjustment information to the target feedback unit, so that the target feedback unit determines the feedback signal based on the judgment signal.

[0018] In some embodiments, the determining unit is further configured to determine a determining signal based on the magnitude of the received modulated signal and the cumulative time of the modulated signal.

[0019] In some embodiments, the determination unit includes a comparator, a first low-pass filter, and a Schmitt trigger;

[0020] The first signal processing unit is connected to the positive input terminal of the comparator through the first low-pass filter. The negative input terminal of the comparator is connected to one end of the first adjustable resistor and one end of the pull-up resistor, respectively. The other end of the first adjustable resistor is connected to the equivalent ground terminal, and the other end of the pull-up resistor is configured to be connected to the first voltage.

[0021] The first low-pass filter includes a second adjustable resistor, which is used to adjust the time constant of the first low-pass filter;

[0022] The output of the comparator is connected to the second selection unit via the Schmitt trigger.

[0023] In some embodiments, the first signal processing unit includes a bandpass filter, a phase-sensitive detector subunit, and a second low-pass filter connected in sequence.

[0024] In the case where the control module includes a first selection unit, the bandpass filter is also connected to the first selection unit, and the second low-pass filter is connected to the judgment unit;

[0025] In the absence of a first selection unit in the control module, the bandpass filter is also connected to the second signal processing unit, and the second low-pass filter is connected to the feedback unit.

[0026] In some embodiments, the second signal processing unit includes a common-mode rejection subunit and / or an amplification subunit;

[0027] When the second signal processing unit includes a common-mode suppression subunit and an amplification subunit, the common-mode suppression subunit is connected to the amplification subunit and the corresponding probe, respectively; and when the control module includes a first selection unit, the amplification subunit is also connected to the first selection unit; and when the control module does not include a first selection unit, the amplification subunit is also connected to the first signal processing unit.

[0028] In some embodiments, the diameter of the magnetic core of each probe is different.

[0029] Secondly, this application also proposes a current detection device, including any of the detection circuits described above.

[0030] This application proposes a current detection circuit, comprising: a control module and m probes, where m is greater than or equal to 1; each probe includes: a fluxgate comprising two first induction coils, two first feedback coils, two first magnetic cores, and two excitation coils connected in series; the two excitation coils are wound in opposite directions around the two first magnetic cores, the two first induction coils are wound in the same direction around the two first magnetic cores, and the two first feedback coils are wound in the same direction around the two first magnetic cores; a mutual inductance module comprising a second induction coil, a second feedback coil, and a second magnetic core; the second induction coil and the second feedback coil are both wound around the second magnetic core; wherein the first induction coil and the second induction coil are wound in the same direction, and the first feedback coil and the second feedback coil are wound in the same direction; in each probe, the second induction coil and each first induction coil are connected in series to form an induction closed loop; the second feedback coil and each first feedback coil are connected in series; the control module is used to acquire the induction signal of the induction closed loop and determine a feedback signal based on the induction signal to control the feedback current of the feedback coil. This application improves the bandwidth of each probe by adding a mutual inductance module to each probe, thus expanding its applicability. Attached Figure Description

[0031] 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.

[0032] Figure 1 This is one of the module structure diagrams of a current detection circuit according to an embodiment;

[0033] Figure 2 The second module structure diagram of a current detection circuit is shown in one embodiment.

[0034] Figure 3 The third module structure diagram of a current detection circuit according to one embodiment;

[0035] Figure 4 This is a circuit structure diagram of the judgment unit of a current detection circuit according to one embodiment;

[0036] Figure 5 The fourth module structure diagram of a current detection circuit is shown in one embodiment.

[0037] Figure labeling: 100-Probe; 110-Fluidgate; 111-First induction coil; 112-First feedback coil; 113-First magnetic core; 114-Excitation coil; 115-Excitation source; 120-Mutual inductance module; 121-Second induction coil; 122-Second feedback coil; 123-Second magnetic core; 200-Control module; 210-First signal processing unit; 220-Second signal processing unit; 221-Common-mode suppression subunit; 222-Amplification subunit; 230-Feedback unit; 240-First selection unit; 250-Second selection unit; 260-Judgment unit; 261-Comparator; 262-First low-pass filter; 263-Schmitt trigger; R-Pull-up resistor; Rt1-First adjustable resistor; Rt2-Second adjustable resistor; C-Capacitor. Detailed Implementation

[0038] 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.

[0039] 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.

[0040] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, 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 resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0041] 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.

[0042] 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.

[0043] 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 features, wholes, steps, operations, components, parts, or combinations 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. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0044] In related fields, the design and structural limitations of current detection devices restrict their measurement bandwidth, thus narrowing their application scenarios and scope.

[0045] To address the aforementioned problems, this application proposes a current detection circuit.

[0046] In some embodiments, the current detection circuit includes a control module 200 and m probes 100, where m is an integer greater than or equal to 1. Each probe 100 includes a fluxgate 110 and a mutual inductance module 120. The circuit structure varies depending on the value of m. Therefore, for ease of explanation, the following is given: Figure 1 The circuit diagram shown is for a circuit where m equals 1.

[0047] The fluxgate 110 includes two first induction coils 111, two first feedback coils 112, two first magnetic cores 113, and two excitation coils 114 connected in series. The two excitation coils 114 are wound in opposite directions around the two first magnetic cores 113, the two first induction coils 111 are wound in the same direction around the two first magnetic cores 113, and the two first feedback coils 112 are wound in the same direction around the two first magnetic cores 113.

[0048] Understandably, the two first magnetic cores 113 are symmetrically arranged. One of the two first induction coils 111, the first induction coil 111a, is wound around the first magnetic core 113a of the two first magnetic cores 113, and the other first induction coil 111b is wound around the other first magnetic core 113b of the two first magnetic cores 113. The two first induction coils 111 are wound in the same direction. One of the two excitation coils 114, the excitation coil 114a, is wound around the first magnetic core 113a, and the other excitation coil 114b is wound around the other first magnetic core 113b. The two excitation coils 114 are wound in opposite directions. One of the two first feedback coils 112, the first feedback coil 112a, is wound around the first magnetic core 113a, and the other first feedback coil 112b is wound around the other first magnetic core 113b. The two first feedback coils 112 are wound in the same direction.

[0049] The fluxgate 110 also includes an excitation source 115, which, together with two excitation coils 114, forms a closed excitation circuit. The excitation source 115 causes the excitation coils 114 to periodically drive the magnetic core towards positive and negative saturation. Within the saturation range, the magnetic flux no longer changes linearly with the external magnetic field. When the probe 100 detects the object being measured, the magnetic field generated by the object is superimposed on the excitation magnetic field, disrupting the original balance. That is, the saturation moments of the positive and negative half-cycles of the magnetic core are no longer odd-symmetric, and even harmonics (especially the second harmonic) appear on the induction coil. By detecting the even harmonics on the induction coil, the magnetic field strength of the object being measured can be detected.

[0050] The mutual inductance module 120 includes a second induction coil 121, a second feedback coil 122, and a second magnetic core 123; both the second induction coil 121 and the second feedback coil 122 are wound around the second magnetic core 123.

[0051] Since the fluxgate 110 mainly detects low-frequency (quasi-DC) magnetic fields, its detection bandwidth is relatively narrow. To enable simultaneous detection of both low-frequency and high-frequency magnetic fields, this embodiment provides a mutual inductance module 120, allowing the entire probe 100 to detect both high-frequency and low-frequency currents. The first induction coil 111 and the second induction coil 121 are wound in the same direction, as are the first feedback coil 112 and the second feedback coil 122.

[0052] In each probe 100, the second induction coil 121 and each first induction coil 111 are connected in series to form an induction closed loop; the second feedback coil 122 and each first feedback coil 112 are connected in series.

[0053] Understandably, the second induction coil 121 and the two first induction coils 111 are connected in series to form an induction closed loop circuit, wherein one end of the first induction coil 111a is connected to one end of the first induction coil 111b, the other end of the first induction coil 111b is connected to one end of the second induction coil 121, and the other end of the second induction coil 121 is connected to the other end of the first induction coil 111a.

[0054] The control module 200 is used to acquire the induction signal of the induction closed loop and determine the feedback signal based on the induction signal to control the feedback current of the feedback coil.

[0055] Understandably, the control module 200 detects the induced signal in the closed-loop induction circuit, which includes even harmonics (second harmonics). Based on the acquired induced signal, the control module 200 determines the feedback current. By allowing the feedback current to flow through the feedback coil, the feedback coil generates a magnetic field of equal magnitude but opposite direction to the magnetic field of the object being measured, thus bringing the magnetic core to a zero-flux state. In this way, physical quantities such as the magnetic field strength of the object being measured can be measured based on the feedback current. The feedback current of the feedback coil refers to the current in the series circuit of the three feedback coils: the first feedback coil 112a, the first feedback coil 112b, and the second feedback coil 122.

[0056] Optionally, the magnetic cores in the fluxgate 110 can also be an even number, such as 4 or 6, without any limitation; the magnetic cores in the mutual inductance module 120 can also be other numbers, such as 2 or 3, without any limitation.

[0057] This embodiment increases the bandwidth of the probe 100 by adding a mutual inductance module 120, which compensates for the limitation of the fluxgate 110 in only detecting high-frequency current, and also improves the resolution and sensitivity of the probe 100.

[0058] In some embodiments, such as Figure 1 As shown, in the current detection circuit, when m equals 1, the control module 200 includes a first signal processing unit 210, a second signal processing unit 220, and a feedback unit 230.

[0059] The first signal processing unit 210 is connected to the two ends of the series connection of the two first induction coils 111 through the second signal processing unit 220. The first signal processing unit 210 is also connected to the two ends of the series connection of the two first feedback coils 112 and the second feedback coil 122 through the feedback unit 230.

[0060] Understandably, one end of the first induction coil 111a is connected to one end of the first induction coil 111b, and the first signal processing unit 210 is connected to the other ends of the first induction coil 111a and the first induction coil 111b respectively through the second signal processing unit 220. The two ends of the series connection of the two first induction coils 111a and 111b refer to the other ends of the first induction coil 111a and 111b, respectively. Similarly, one end of the first feedback coil 112a is connected to one end of the first feedback coil 112b, and the other end of the first feedback coil 112b is connected to one end of the second feedback coil 122. The first signal processing unit 210 is also connected to the other ends of the first feedback coil 112a and the second feedback coil 122 respectively through the feedback unit 230. The two ends of the series connection of these three coils refer to the other ends of the first feedback coil 112a and the second feedback coil 122, respectively.

[0061] The second signal processing unit 220 is used to determine the first target signal based on the acquired sensing signal; the first signal processing unit 210 demodulates the first target signal to determine the modulation signal; and the feedback unit 230 determines the feedback signal based on the modulation signal.

[0062] Understandably, due to the characteristics of the acquired induced signal, such as the presence of interference signals or weak induced signals, it is necessary to perform pre-processing by the second signal processing unit 220 to obtain a higher quality signal, namely the first target signal. Even after pre-processing, the first target signal is still not a clean DC signal because it also includes second harmonics, mixed fundamental frequencies, third harmonics, noise, etc. Therefore, it is necessary to demodulate and suppress the fundamental frequencies, odd harmonics, and noise to obtain a useful DC voltage signal, namely the modulated signal. This modulated signal is the desired signal that is proportional to the measured DC magnetic field.

[0063] In some embodiments, such as Figure 2 As shown, when m is greater than 1, the control module 200 in the current detection circuit includes a first signal processing unit 210, a first selection unit 240, a second selection unit 250, a judgment unit 260, m second signal processing units 220 and m feedback units 230, and each probe 100 corresponds to a second signal processing unit 220 and a feedback unit 230 respectively.

[0064] The first selection unit 240 is connected to each of the second signal processing units 220, and each of the second signal processing units 220 is connected to the two ends of the series connection of the two first induction coils 111 in the corresponding probe 100.

[0065] The first selection unit 240 is also connected to the second selection unit 250 in sequence through the first signal processing unit 210 and the judgment unit 260. The second selection unit 250 is also connected to each feedback unit 230. Each feedback unit 230 is connected to the two ends of the series connection of the two first feedback coils 112 and the second feedback coil 122 in the corresponding probe 100.

[0066] Understandably, one end of the first feedback coil 112 is connected to one end of another first feedback coil 112, and the other end of the other feedback coil is connected to one end of the second feedback coil 122. Specifically, each feedback unit 230 connects to both ends of the series connection of the three coils (two first feedback coils 112 and two second feedback coils 122) in the corresponding probe 100. This means that each feedback unit 230 connects to the other end of the aforementioned first feedback coil 112 and second feedback coil 122 in the corresponding probe 100.

[0067] For ease of explanation, let's take a current detection circuit with m equal to 2 as an example, such as... Figure 3As shown, probe 100a corresponds to the second signal processing unit 220a and the feedback unit 230a, respectively, and probe 100b corresponds to the second signal processing unit 220b and the feedback unit 230b, respectively. The first selection unit 240 is connected to the second signal processing unit 220a and the second signal processing unit 220b, and the second selection unit 250 is connected to the feedback unit 230a and the feedback unit 230b. (Combined...) Figure 1 and Figure 2 It can be seen that the feedback unit 230a is connected to the other end of the first feedback coil 112a and the other end of the second feedback coil 122 in the probe 100a respectively; the feedback unit 230b is connected to the other end of the first feedback coil 112a and the other end of the second feedback coil 122 in the probe 100b respectively.

[0068] Optionally, in order to improve the accuracy of detection, this embodiment includes multiple probes 100 with different ranges. The diameter of the magnetic core of each probe 100 is different, and the range of the corresponding probe 100 is different.

[0069] In some embodiments, the second signal processing unit 220 is used to determine a first target signal based on the acquired sensing signal; the first signal processing unit 210 performs demodulation based on the first target signal to determine a modulation signal.

[0070] Understandably, when m is greater than 1, the demodulation process of the first signal processing unit 210 in the circuit can refer to the demodulation process in the circuit when m equals 1, as described above, and will not be repeated here.

[0071] The judgment unit 260 is used to determine the judgment signal based on the modulation signal and transmit the judgment signal carrying the target probe information to the first selection unit 240 and the second selection unit 250 respectively, so that the first selection unit 240 connects to the target second signal processing unit corresponding to the target probe information and disconnects the second signal processing unit 220 corresponding to the non-target probe information based on the judgment signal, and the second selection unit 250 connects to the target feedback unit corresponding to the target probe information based on the judgment signal.

[0072] Understandably, the modulation signal varies in magnitude. Based on the magnitude of the modulation signal, it can be determined whether a large or small range probe 100 is currently being used, thus identifying the target probe. A judgment signal carrying the target probe information is transmitted to the first selection unit 240 and the second selection unit 250. The first selection unit 240 disconnects all second signal processing units 220 corresponding to non-target probes and connects to the target second signal processing unit corresponding to the target probe based on the judgment signal. The second selection unit 250 connects to the target feedback unit corresponding to the target probe based on the judgment signal. Here, the feedback unit 230 corresponding to the target probe is the target feedback unit, and the second signal processing unit 220 corresponding to the target probe is the target second signal processing unit. The target probe information is used to instruct the first selection unit 240 to select the second signal processing unit 220 corresponding to the target probe, and to instruct the second selection unit 250 to select the feedback unit 230 corresponding to the target probe.

[0073] For example, if there are two probes 100 with different ranges, namely 0~10A and 0~100A, and if the modulation signal corresponding to the induced current measured by the two probes 100 is within a preset range (e.g., the modulation signal range corresponding to 0~8A), then the probe 100 with the 0~10A range is selected as the target probe. At this time, the judgment unit 260 will output a judgment signal carrying the 0~10A range probe 100. Then, a low level can be output to indicate that the probe 100 with the lower range is selected. Conversely, if the modulation signal corresponding to the induced current measured by the probes 100 with two ranges is not within the preset range (e.g., the modulation signal range corresponding to 0~8A), then the probe 100 with a range of 0~100A is used as the target probe. At this time, the judgment unit 260 will output a judgment signal carrying the 0~100A range probe 100. A high-level signal can then be output to indicate the selection of the higher-range probe 100. After receiving the judgment signal, the first selection unit 240 and the second selection unit 250 connect the corresponding probe 100 according to the judgment signal.

[0074] For example, if the first selection unit 240 receives a high-level signal, the first selection unit 240 switches from the initial state of "simultaneously connecting the second signal processing units 220 corresponding to both probes 100" to the state of "only connecting the second signal processing unit 220 corresponding to the high-range probe 100 (target probe) (target second signal processing unit)", and disconnects from the second signal processing unit 220 corresponding to the other low-range probe 100; the second selection unit 250 only connects to the feedback unit 230 (target feedback unit) corresponding to the high-range probe 100 (target probe).

[0075] The first selection unit 240 is also used to transmit a judgment signal carrying feedback adjustment information to the target feedback unit so that the target feedback unit determines the feedback signal based on the judgment signal.

[0076] Understandably, the target feedback unit calculates the feedback signal based on the judgment signal. In some embodiments, the judgment signal is a digital signal that includes the amplitude and direction information of the measured current. The feedback signal can be calculated based on the judgment signal to obtain a feedback current signal, which causes the feedback coil to generate a magnetic field to bring the magnetic core to a zero flux state.

[0077] In some embodiments, the judgment unit 260 in the current detection circuit is further configured to determine a judgment signal based on the magnitude of the received modulated signal and the cumulative time of the modulated signal.

[0078] Understandably, to ensure greater stability of the entire control module 200, during actual use, instantaneous test values ​​may be excessively large. This would cause frequent changes in the judgment value output by the judgment unit 260, resulting in numerous and large fluctuations in the measured value, thus affecting the accuracy of the measurement results. For accurate measurement, optionally, the judgment unit 260 will only output a corresponding judgment signal and transmit it to the second selection unit 250 when the modulation signal magnitude meets a preset range and the cumulative time within that range meets a preset duration condition. This allows for switching between different range probes 100. Exemplarily, if the modulation signal is less than the judgment threshold (within a preset low-level range) for more than a first cumulative time within a first preset time, the output judgment signal is a low-level signal. If the modulation signal is greater than the judgment threshold (within a preset high-level range) for more than a second cumulative time within a second preset time, the output judgment signal is a high-level signal.

[0079] In some embodiments, such as Figure 4 As shown, the judgment unit 260 in the current detection circuit includes a comparator 261, a first low-pass filter 262, and a Schmitt trigger 263.

[0080] The first signal processing unit 210 is connected to the positive input terminal of comparator 261 via a first low-pass filter 262. The negative input terminal of comparator 261 is connected to one end of a first adjustable resistor Rt1 and a pull-up resistor R, respectively. The other end of the first adjustable resistor Rt1 is connected to an equivalent ground terminal, and the other end of the pull-up resistor R is configured to be connected to a first voltage. The first low-pass filter 262 includes a second adjustable resistor Rt2 and a capacitor C. The second adjustable resistor Rt2 is used to adjust the time constant of the first low-pass filter 262. The output terminal of comparator 261 is connected to the second selection unit 250 via a Schmitt trigger 263.

[0081] Understandably, the first low-pass filter 262 can not only effectively filter high-frequency signals, but also increase the stability and anti-interference capability of the probe 100 by utilizing its delay characteristics and those of the Schmitt trigger 263. Specifically, the first low-pass filter 262 controls the delay duration, while the Schmitt trigger 263 ensures stable triggering after the delay. Since the time constant is the product of the resistance of the second adjustable resistor Rt2 and the capacitance C of the capacitor C, the time constant of the first low-pass filter 262 (RC filter) can be adjusted by changing the value of the second adjustable resistor Rt2. Simultaneously, the judgment threshold can be changed by adjusting the first adjustable resistor Rt1, i.e., changing the preset range. However, the delay effect of the first low-pass filter 262 cannot completely ensure a clean output from the comparator 261. This is because voltage noise exists; when the voltage fluctuates, it causes the voltage value to jump around a certain value, resulting in frequent changes in the output of the comparator 261. This leads to instability in the measurement results of the entire probe 100, i.e., weak anti-interference capability. Therefore, a Schmitt trigger 263 needs to be connected to the output of the comparator 261 to delay the output and improve the stability and anti-interference of the triggering action. In this way, the Schmitt trigger 263 will only trigger when the output value of the first low-pass filter 262 is greater than or less than the comparison threshold within a certain period of time.

[0082] In some embodiments, the first signal processing unit 210 in the current detection circuit includes a bandpass filter, a phase-sensitive detector subunit, and a second low-pass filter connected in sequence.

[0083] Understandably, the bandpass filter outputs the second harmonic component of the excitation square wave frequency with the highest waveform amplitude from the probe 100 to the phase-sensitive detector subunit. The phase-sensitive detector subunit demodulates the received second harmonic. Specifically, since the carrier frequency of the phase-sensitive detector subunit is twice the square wave frequency of the excitation source 115, it can obtain a waveform containing the input signal information by multiplying it with the input signal, suppressing other even harmonic components of the carrier frequency, and suppressing odd harmonic components, finally obtaining the required relatively pure second harmonic signal. Since this second harmonic signal still contains high-frequency residual components, it is also necessary to perform low-pass filtering on the second harmonic signal to obtain the required judgment signal.

[0084] Optionally, different bandpass filters have different costs and filtering performance. For example, a first-order filter has a roll-off rate of -20dB, slow attenuation, poor selectivity, and cannot effectively separate the target signal. A second-order filter has a roll-off rate of -40dB, and a fourth-order filter has a roll-off rate of -80dB. If a second-order filter is used, its suppression may only be -12dB (referring to suppression of f at 2f, where f is the excitation frequency), which does not meet the practical requirements. A fourth-order filter, on the other hand, may achieve a suppression of -24dB, with better performance. To comprehensively consider cost and filtering performance, a fourth-order bandpass filter, such as a fourth-order Sallen-key bandpass filter, can be selected. Of course, other filters can be selected in different scenarios, and there are no restrictions here.

[0085] When the control module 200 includes a first selection unit 240, a bandpass filter is also connected to the first selection unit 240, and a second low-pass filter is connected to the judgment unit 260.

[0086] In the absence of the first selection unit 240 in the control module 200, the bandpass filter is also connected to the second signal processing unit 220, and the second low-pass filter is connected to the feedback unit 230.

[0087] Understandably, the circuit structure of control module 200 differs depending on the value of m. When m is greater than 1, control module 200 includes the first selection unit 240. When m equals 1, control module 200 does not include the first selection unit 240. This is because no selection is needed when there is only one probe 100.

[0088] In some embodiments, the second signal processing unit 220 in the current detection circuit includes a common-mode suppression subunit 221 and / or an amplification subunit 222.

[0089] Understandably, before entering the first signal processing unit 210, the induced signal output is a differential-mode signal with second harmonics, which contains common-mode interference signals (such as odd harmonics, excitation leakage, ground loop current, power supply coupling, etc.). Therefore, common-mode rejection processing is required. Of course, the induced signal is relatively weak, and in order to ensure the improvement of signal processing effect, a sufficient signal-to-noise ratio needs to be guaranteed. Therefore, signal amplification processing is also required.

[0090] In this embodiment, various structures of the second signal processing unit 220 are proposed. For example, the second signal processing unit 220 includes a common-mode suppression subunit 221, an amplification subunit 222, and a common-mode suppression subunit 221 and an amplification subunit 222.

[0091] When the second signal processing unit 220 includes a common-mode rejection subunit 221 and an amplification subunit 222, such as Figure 5 As shown, the common-mode suppression subunit 221 is connected to the amplification subunit 222 and the corresponding probe 100 respectively; and when the control module 200 includes the first selection unit 240, the amplification subunit 222 is also connected to the first selection unit 240; and when the control module 200 does not include the first selection unit 240, the amplification subunit 222 is also connected to the first signal processing unit 210.

[0092] Understandably, when the second signal processing unit 220 includes both a common-mode rejection subunit 221 and an amplification subunit 222, the number of probes 100 can be one or more. Therefore, when the second signal processing unit 220 includes both a common-mode rejection subunit 221 and an amplification subunit 222, the number of probes 100 also needs to be discussed. When the second signal processing unit 220 includes both a common-mode rejection subunit 221 and an amplification subunit 222, if m is 1, it indicates that the control module 200 does not include the first selection unit 240. In this case, the amplification subunit 222 is also connected to the first signal processing unit 210. When the second signal processing unit 220 includes both a common-mode rejection subunit 221 and an amplification subunit 222, if m is greater than 1, it indicates that the control module 200 includes the first selection unit 240, the second selection unit 250, and the judgment unit 260. In this case, the amplification subunit 222 is also connected to the first selection unit 240.

[0093] This application improves the bandwidth of each probe 100 by adding a mutual inductance module 120 to each probe 100. It also proposes a detection circuit for multiple probes 100, each with a different measurement range. The appropriate probe 100 is selected for measurement based on the induced current of the object being measured, thereby improving the accuracy of the measurement results. Furthermore, while fulfilling the above functional requirements, suitable components are selected to reduce costs.

[0094] This application also proposes a current detection device, including any of the above-described current detection circuits.

[0095] Understandably, the above-described current detection circuit options can also be used in the current detection device of this embodiment, and will not be described in detail here.

[0096] 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.

[0097] 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.

[0098] 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 current detection circuit, characterized in that, include: The control module and m probes, where m is greater than or equal to 1; each probe includes: A fluxgate includes two first induction coils, two first feedback coils, two first magnetic cores, and two excitation coils connected in series; the two excitation coils are wound in opposite directions around the two first magnetic cores, the two first induction coils are wound in the same direction around the two first magnetic cores, and the two first feedback coils are wound in the same direction around the two first magnetic cores. The mutual inductance module includes a second induction coil, a second feedback coil, and a second magnetic core; both the second induction coil and the second feedback coil are wound around the second magnetic core; wherein the first induction coil and the second induction coil are wound in the same direction, and the first feedback coil and the second feedback coil are wound in the same direction. In each of the probes, the second induction coil and each of the first induction coils are connected in series to form an induction closed loop; the second feedback coil and each of the first feedback coils are connected in series. The control module is used to acquire the induction signal of the induction closed loop and determine the feedback signal based on the induction signal to control the feedback current of the feedback coil.

2. The detection circuit according to claim 1, characterized in that, When m equals 1, the control module includes a first signal processing unit, a second signal processing unit, and a feedback unit; The first signal processing unit is connected to the two ends of the series connection of the two first induction coils through the second signal processing unit. The first signal processing unit is also connected to the two ends of the series connection of the two first feedback coils and the second feedback coil through the feedback unit. The second signal processing unit is used to determine a first target signal based on the acquired sensing signal; the first signal processing unit performs demodulation based on the first target signal to determine a modulation signal; The feedback unit determines the feedback signal based on the modulation signal.

3. The detection circuit according to claim 1, characterized in that, When m is greater than 1, the control module includes a first signal processing unit, a first selection unit, a second selection unit, a judgment unit, m second signal processing units and m feedback units, and each probe corresponds to one second signal processing unit and one feedback unit respectively; The first selection unit is connected to each of the second signal processing units, and each of the second signal processing units is connected to the two ends of the series connection of the two first induction coils in the corresponding probe. The first selection unit is also connected to the second selection unit in sequence through the first signal processing unit and the judgment unit. The second selection unit is also connected to each of the feedback units. Each feedback unit is connected to the two ends of the three coils connected in series: the two first feedback coils and the second feedback coil in the corresponding probe.

4. The detection circuit according to claim 3, characterized in that, The second signal processing unit is used to determine a first target signal based on the acquired sensing signal; the first signal processing unit performs demodulation based on the first target signal to determine a modulation signal; The judgment unit is configured to determine a judgment signal based on the modulation signal, and transmit the judgment signal carrying the target probe information to the first selection unit and the second selection unit respectively, so that the first selection unit connects to the target second signal processing unit corresponding to the target probe information and disconnects from the second signal processing unit corresponding to the non-target probe information based on the judgment signal, and the second selection unit connects to the target feedback unit corresponding to the target probe information based on the judgment signal. The first selection unit is further configured to transmit the judgment signal carrying feedback adjustment information to the target feedback unit, so that the target feedback unit determines the feedback signal based on the judgment signal.

5. The detection circuit according to claim 4, characterized in that, The judgment unit is further configured to determine a judgment signal based on the magnitude of the received modulated signal and the cumulative time of the modulated signal.

6. The detection circuit according to any one of claims 3 to 5, characterized in that, The judgment unit includes a comparator, a first low-pass filter, and a Schmitt trigger; The first signal processing unit is connected to the positive input terminal of the comparator through the first low-pass filter. The negative input terminal of the comparator is connected to one end of the first adjustable resistor and one end of the pull-up resistor, respectively. The other end of the first adjustable resistor is connected to the equivalent ground terminal, and the other end of the pull-up resistor is configured to be connected to the first voltage. The first low-pass filter includes a second adjustable resistor, which is used to adjust the time constant of the first low-pass filter; The output of the comparator is connected to the second selection unit via the Schmitt trigger.

7. The detection circuit according to any one of claims 2 to 5, characterized in that, The first signal processing unit includes a bandpass filter, a phase-sensitive detector subunit, and a second low-pass filter connected in sequence. In the case where the control module includes a first selection unit, the bandpass filter is also connected to the first selection unit, and the second low-pass filter is connected to the judgment unit; In the absence of a first selection unit in the control module, the bandpass filter is also connected to the second signal processing unit, and the second low-pass filter is connected to the feedback unit.

8. The detection circuit according to any one of claims 2 to 5, characterized in that, The second signal processing unit includes a common-mode rejection subunit and / or an amplification subunit; When the second signal processing unit includes a common-mode suppression subunit and an amplification subunit, the common-mode suppression subunit is connected to the amplification subunit and the corresponding probe, respectively; and when the control module includes a first selection unit, the amplification subunit is also connected to the first selection unit; and when the control module does not include a first selection unit, the amplification subunit is also connected to the first signal processing unit.

9. The detection circuit according to claim 1, characterized in that, The diameter of the magnetic core of each probe is different.

10. A current detection device, characterized in that, The detection circuit includes any one of claims 1 to 9.

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