Fluxgate sensor circuit and fluxgate sensor

Abstract

The invention relates to a fluxgate sensor circuit and a fluxgate sensor. The fluxgate sensor circuit comprises a direct current zero point detector, an alternating current zero point detector, a magnetic flux compensation unit and a magnetic flux excitation auxiliary unit; the direct current zero point detector is used for generating a voltage induction signal and a first excitation voltage according to the detected current and transmitting the voltage induction signal and the first excitation voltage to the magnetic flux excitation auxiliary unit; the magnetic flux excitation auxiliary unit is used for determining a direct current voltage signal according to the voltage induction signal under the action of the first excitation voltage and transmitting the direct current voltage signal to the alternating current zero point detector; the alternating current zero point detector is used for generating an alternating current voltage signal according to the detected current and transmitting the direct current voltage signal and the alternating current voltage signal to the magnetic flux compensation unit; and the magnetic flux compensation unit is used for determining compensation current according to the direct-current voltage signal and the alternating-current voltage signal, and determining the magnetic flux of the detected current according to the compensation current, so that the reliability and the stability of the fluxgate sensor can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of fluxgate sensors, and in particular to a fluxgate sensor circuit and a fluxgate sensor. Background Art

[0002] The fluxgate sensor is a highly sensitive instrument that can detect external magnetic fields using the magnetostrictive effect or the magnetogyroscopic effect. It is widely used in scientific research, industrial testing, military applications and other fields.

[0003] In the prior art, when facing a high-precision magnetic field measurement scenario, the fluxgate sensor has a problem of poor measurement accuracy, which leads to poor reliability and stability of the fluxgate sensor. Summary of the invention

[0004] Based on this, it is necessary to provide a fluxgate sensor circuit and a fluxgate sensor with high measurement accuracy to address the above technical problems, thereby improving the reliability and stability of the fluxgate sensor.

[0005] In a first aspect, the present application provides a fluxgate sensor circuit, which includes a DC current zero point detector, an AC current zero point detector, a flux compensation unit, and a flux excitation auxiliary unit; wherein the DC current zero point detector is connected to the flux excitation auxiliary unit and the flux compensation unit, and the AC current zero point detector is connected to the DC current zero point detector and the flux compensation unit;

[0006] The DC current zero point detector is used to generate a voltage sensing signal and a first excitation voltage according to the measured current, and transmit the voltage sensing signal and the first excitation voltage to the magnetic flux excitation auxiliary unit;

[0007] The magnetic flux excitation auxiliary unit is used to determine a DC voltage signal according to the voltage sensing signal under the action of the first excitation voltage, and transmit the DC voltage signal to the AC current zero point detector;

[0008] The AC current zero point detector is used to generate an AC voltage signal according to the measured current, and transmit the DC voltage signal and the AC voltage signal to the magnetic flux compensation unit;

[0009] The magnetic flux compensation unit is used to determine a compensation current according to the DC voltage signal and the AC voltage signal, and to determine the magnetic flux of the measured current according to the compensation current.

[0010] In one embodiment, the flux excitation auxiliary unit is specifically used to determine the second excitation voltage according to the voltage sensing signal under the action of the first excitation voltage, and add the voltage sensing signal and the second excitation voltage, and transmit the added voltage sensing signal and the second excitation voltage to the DC current zero point detector, so that the DC current zero point detector determines the DC voltage signal according to the added voltage sensing signal and the second excitation voltage, and transmits the DC voltage signal to the AC current zero point detector.

[0011] In one embodiment, the DC current zero point detector includes a first magnetic core, a first winding, a first sampling resistor, a current limiting resistor, a Schmitt trigger and a low-pass filter; wherein the first winding is wound on the first magnetic core, one end of the first winding is connected to the current limiting resistor, and the other end is connected to the Schmitt trigger and the flux excitation auxiliary unit, one end of the Schmitt trigger is connected to the first sampling resistor, the current limiting resistor and the low-pass filter, and the other end is connected to the flux excitation auxiliary unit, one end of the first sampling resistor is grounded, and the other end is connected to the low-pass filter, the current limiting resistor and the Schmitt trigger; one end of the current limiting resistor is connected to the first sampling resistor, the low-pass filter and the Schmitt trigger The first magnetic core, the first winding, the first sampling resistor, the current limiting resistor, the Schmitt trigger and the magnetic flux excitation auxiliary unit are connected at one end, and the other end is connected to the magnetic flux compensation unit; the first magnetic core, the first winding, the first sampling resistor, the current limiting resistor and the Schmitt trigger are used to generate the voltage sensing signal and the first excitation voltage according to the measured current, and transmit the voltage sensing signal and the first excitation voltage to the magnetic flux excitation auxiliary unit; the low-pass filter is used to determine the DC voltage signal according to the voltage sensing signal and the second excitation voltage after the addition processing, and transmit the DC voltage signal to the AC current zero point detector.

[0012] In one embodiment, the low-pass filter is specifically used to filter the voltage sensing signal and the second excitation voltage after the addition process to obtain the DC voltage signal, and transmit the DC voltage signal to the AC current zero point detector.

[0013] In one embodiment, the flux excitation auxiliary unit includes a second magnetic core, a second winding, a unit gain inverter, a high pass filter and a second sampling resistor; wherein the second winding is wound on the second magnetic core, one end of the second winding is connected to the unit gain inverter, and the other end is connected to the high pass filter and the second sampling resistor, one end of the unit gain inverter is connected to the second winding, and the other end is connected to the Schmitt trigger and the first winding, one end of the second sampling resistor is grounded, and the other end is connected to the second winding, one end of the high pass filter is connected to the second winding and the second sampling resistor, and the other end is connected to the low pass filter; the second magnetic core, the second winding, the unit gain inverter and the second sampling resistor are used to determine the second excitation voltage according to the voltage sensing signal under the action of the first excitation voltage, and transmit the second excitation voltage and the voltage sensing signal to the high pass filter; the high pass filter is used to perform sum processing on the second excitation voltage and the voltage sensing signal, and transmit the voltage sensing signal and the second excitation voltage after the sum processing to the DC current zero point detector.

[0014] In one embodiment, the AC current zero point detector includes a third magnetic core and a third winding; wherein the third winding is wound on the third magnetic core, one end of the third winding is grounded, and the other end is connected to the flux compensation unit; the third magnetic core and the third winding are used to generate an AC voltage signal according to the measured current, and transmit the DC voltage signal and the AC voltage signal to the flux compensation unit.

[0015] In one embodiment, the magnetic flux compensation unit includes a proportional integrator, a driving unit, a measuring resistor, and a compensation winding; wherein, one end of the proportional integrator is connected to the low-pass filter and the third winding, and the other end is connected to the driving unit, one end of the driving unit is connected to the proportional integrator, and the other end is connected to the compensation winding, the compensation winding is wound on the first magnetic core and the third magnetic core, one end of the compensation winding is connected to the driving unit, and the other end is connected to the measuring resistor, one end of the measuring resistor is grounded, and the other end is connected to the compensation winding; the proportional integrator, the driving unit, the measuring resistor and the compensation winding are used to determine the compensation current according to the DC voltage signal and the AC voltage signal, and determine the magnetic flux of the measured current according to the compensation current.

[0016] In one embodiment, the voltage sensing signal and the second excitation voltage are equal in magnitude and opposite in direction.

[0017] In one embodiment, the first magnetic core has the same parameters as the second magnetic core, and the first winding has the same parameters as the second winding.

[0018] In a second aspect, the present application further provides a fluxgate sensor, which includes the fluxgate sensor circuit described in any embodiment of the first aspect.

[0019] The fluxgate sensor circuit and fluxgate sensor are as follows: the fluxgate sensor circuit includes a DC current zero point detector, an AC current zero point detector, a flux compensation unit, and a flux excitation auxiliary unit; wherein the DC current zero point detector is connected to the flux excitation auxiliary unit and the flux compensation unit, and the AC current zero point detector is connected to the DC current zero point detector and the flux compensation unit; the DC current zero point detector is used to generate a voltage sensing signal and a first excitation voltage according to the measured current, and transmit the voltage sensing signal and the first excitation voltage to the flux excitation auxiliary unit; the flux excitation auxiliary unit is used to determine a DC voltage signal according to the voltage sensing signal under the action of the first excitation voltage, and transmit the DC voltage signal to the AC current zero point detector; the AC current zero point detector is used to generate an AC voltage signal according to the measured current, and transmit the DC voltage signal and the AC voltage signal to the flux compensation unit; the flux compensation unit is used to determine a compensation current according to the DC voltage signal and the AC voltage signal, and determine the magnetic flux of the measured current according to the compensation current. The fluxgate sensor circuit provided by the present application is not only simple in circuit, but also can effectively improve the measurement accuracy of the fluxgate sensor, thereby effectively improving the reliability and stability of the fluxgate sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 is a schematic diagram of a fluxgate sensor circuit in one embodiment;

[0022] Figure 2 is a schematic diagram of a fluxgate sensor circuit in another embodiment;

[0023] Figure 3 FIG. 4 is a schematic diagram of the working principles of a high-pass filter and a low-pass filter in one embodiment. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0025] In the description of this application, it should be understood that if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0026] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0027] It should be noted that if an element is referred to as being "wound around" or "set on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If present, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0028] The fluxgate sensor is a highly sensitive instrument that can detect external magnetic fields using the magnetostrictive effect or the magnetogyroscopic effect. It is widely used in scientific research, industrial testing, military applications and other fields.

[0029] In the prior art, when facing a high-precision magnetic field measurement scenario, the fluxgate sensor has a problem of poor measurement accuracy, which leads to poor reliability and stability of the fluxgate sensor.

[0030] In view of this, the present application provides a fluxgate sensor circuit, which can effectively improve the measurement accuracy and thereby improve the reliability and stability of the fluxgate sensor.

[0031] In an exemplary embodiment, Figure 1As shown, a fluxgate sensor circuit 100 is provided. The fluxgate sensor circuit 100 includes a DC current zero point detector 101, an AC current zero point detector 102, a flux compensation unit 103 and a flux excitation auxiliary unit 104.

[0032] The DC current zero point detector 101 is connected to the magnetic flux excitation auxiliary unit 104 and the magnetic flux compensation unit 103 , and the AC current zero point detector 102 is connected to the DC current zero point detector 101 and the magnetic flux compensation unit 103 .

[0033] The DC current zero point detector 101 is used to generate a voltage induction signal and a first excitation voltage according to the measured current, and transmit the voltage induction signal and the first excitation voltage to the flux excitation auxiliary unit 104; the flux excitation auxiliary unit 104 is used to determine a DC voltage signal according to the voltage induction signal under the action of the first excitation voltage, and transmit the DC voltage signal to the AC current zero point detector 102; the AC current zero point detector 102 is used to generate an AC voltage signal according to the measured current, and transmit the DC voltage signal and the AC voltage signal to the flux compensation unit 103; the flux compensation unit 103 is used to determine a compensation current according to the DC voltage signal and the AC voltage signal, and determine the magnetic flux of the measured current according to the compensation current.

[0034] Optionally, the DC current zero point detector 101 refers to a device that can be used to detect the zero-crossing point of the DC signal in the measured current. The AC current zero point detector 102 refers to a device that can be used to detect the zero-crossing point of the AC signal in the measured current. The magnetic flux compensation unit 103 refers to a device that works based on the zero magnetic flux compensation principle, that is, a method of keeping the magnetic flux at zero or a constant value under specific conditions.

[0035] In some exemplary embodiments, when measuring the magnetic flux of the measured current, the DC current zero point detector 101 can first generate a voltage sensing signal and a first excitation voltage according to the measured current, and then transmit the voltage sensing signal and the first excitation voltage to the magnetic flux excitation auxiliary unit 104.

[0036] Furthermore, after the flux excitation auxiliary unit 104 receives the voltage sensing signal and the first excitation voltage transmitted by the DC current zero point detector 101, it will determine the DC voltage signal according to the voltage sensing signal under the action of the first excitation voltage, and transmit the DC voltage signal to the AC current zero point detector 102.

[0037] Furthermore, the AC current zero point detector 102 can generate an AC voltage signal according to the measured current, and transmit the DC voltage signal received from the magnetic flux excitation auxiliary unit 104 and the generated AC voltage signal to the magnetic flux compensation unit 103 .

[0038] Furthermore, after the magnetic flux compensation unit 103 receives the DC voltage signal and the AC voltage signal transmitted by the AC current zero point detector 102, it can determine the compensation current according to the DC voltage signal and the AC voltage signal, and determine the magnetic flux of the measured current according to the compensation current.

[0039] The above-mentioned fluxgate sensor circuit includes a DC current zero point detector, an AC current zero point detector, a flux compensation unit, and a flux excitation auxiliary unit; wherein the DC current zero point detector is connected to the flux excitation auxiliary unit and the flux compensation unit, and the AC current zero point detector is connected to the DC current zero point detector and the flux compensation unit; the DC current zero point detector is used to generate a voltage sensing signal and a first excitation voltage according to the measured current, and transmit the voltage sensing signal and the first excitation voltage to the flux excitation auxiliary unit; the flux excitation auxiliary unit is used to determine a DC voltage signal according to the voltage sensing signal under the action of the first excitation voltage, and transmit the DC voltage signal to the AC current zero point detector; the AC current zero point detector is used to generate an AC voltage signal according to the measured current, and transmit the DC voltage signal and the AC voltage signal to the flux compensation unit; the flux compensation unit is used to determine a compensation current according to the DC voltage signal and the AC voltage signal, and determine the magnetic flux of the measured current according to the compensation current. The fluxgate sensor circuit provided by the present application is not only simple in circuit, but also can effectively improve the measurement accuracy of the fluxgate sensor, thereby effectively improving the reliability and stability of the fluxgate sensor.

[0040] In an exemplary embodiment, the flux excitation auxiliary unit is specifically used to determine the second excitation voltage according to the voltage sensing signal under the action of the first excitation voltage, and add the voltage sensing signal and the second excitation voltage, and transmit the added voltage sensing signal and the second excitation voltage to the DC current zero point detector, so that the DC current zero point detector determines the DC voltage signal according to the added voltage sensing signal and the second excitation voltage, and transmits the DC voltage signal to the AC current zero point detector.

[0041] In an optional embodiment of the present application, the voltage sensing signal and the second excitation voltage are equal in magnitude and opposite in direction. Such a setting can suppress current noise while realizing DC zero flux detection.

[0042] In some exemplary embodiments, after receiving the voltage sensing signal and the first excitation voltage transmitted by the DC current zero point detector 101, the flux excitation auxiliary unit will determine the second excitation voltage based on the voltage sensing signal under the action of the first excitation voltage, and add the voltage sensing signal and the second excitation voltage.

[0043] Furthermore, after the magnetic flux excitation auxiliary unit performs sum processing on the voltage sensing signal and the second excitation voltage, the summed voltage sensing signal and the second excitation voltage are transmitted to the DC current zero point detector.

[0044] After the DC current zero point detector receives the voltage sensing signal and the second excitation voltage after the addition processing transmitted by the flux excitation auxiliary unit, it determines the DC voltage signal based on the voltage sensing signal and the second excitation voltage after the addition processing, and transmits the DC voltage signal to the AC current zero point detector.

[0045] In an exemplary embodiment, Figure 2 As shown, the DC current zero point detector includes a first magnetic core C1, a first winding W1, a first sampling resistor R S1 , current limiting resistor R S3 , Schmitt trigger U1 and low pass filter LPF.

[0046] The first winding W1 is wound on the first magnetic core C1, and one end of the first winding W1 is connected to the current limiting resistor R S3 The other end is connected to the Schmitt trigger U1 and the magnetic flux excitation auxiliary unit. One end of the Schmitt trigger U1 is connected to the first sampling resistor R S1 , the current limiting resistor R S3 and a low-pass filter LPF, and the other end is connected to the magnetic flux excitation auxiliary unit, the first sampling resistor R S1 One end is grounded, and the other end is connected to the low-pass filter LPF and the current limiting resistor R S3 and connected to the Schmitt trigger U1; the current limiting resistor R S3 One end of the first sampling resistor R S1 The low-pass filter LPF is connected to the Schmitt trigger U1, and the other end is connected to the first winding W1. One end of the low-pass filter LPF is connected to the first sampling resistor R S1 , the current limiting resistor R S3 , the Schmitt trigger U1 is connected to the flux excitation auxiliary unit, and the other end is connected to the flux compensation unit.

[0047] The first magnetic core C1, the first winding W1, the first sampling resistor R S1 , the current limiting resistor R S3The Schmitt trigger U1 is used to detect the current W p The voltage sensing signal v is generated s1 and the first excitation voltage v ex1 , and the voltage sensing signal v s1 and the first excitation voltage v ex1 The low-pass filter LPF is used to transmit the voltage sensing signal v after the addition process to the magnetic flux excitation auxiliary unit 104; s1 and the second excitation voltage v s2 Determine the DC voltage signal v dc , and the DC voltage signal v dc Transmitted to the AC current zero point detector 102.

[0048] The first magnetic core refers to a sintered magnetic metal oxide composed of a mixture of various iron oxides, which is used to increase the magnetic flux of the inductor. The first winding W1 can be composed of a coil or a wire turn. The working principle of the low-pass filter LPF can be as follows Figure 3 As shown, the low-pass filter LPF can be used to filter out high-frequency components in the voltage sensing signal and the second excitation voltage after the addition process.

[0049] In some exemplary embodiments, the first magnetic core C1, the first winding W1, the current limiting resistor R S3 The Schmitt trigger U1 can be used according to the measured current W p Generate the first excitation voltage v ex1 The first magnetic core C1, the first winding W1, the current limiting resistor R S3 and the first sampling resistor R S1 According to the measured current W p Generate voltage sensing signal v s1 .

[0050] Furthermore, in the first magnetic core C1, the first winding W1, the first sampling resistor R S1 , the current limiting resistor R S3 The Schmitt trigger U1 is based on the measured current W p The voltage sensing signal v is generated s1 and the first excitation voltage v ex1 After that, the voltage sensing signal v s1 and the first excitation voltage v ex1 Transmitted to the flux excitation auxiliary unit.

[0051] The magnetic flux excitation auxiliary unit receives the voltage sensing signal v transmitted by the DC current zero point detector. s1 and the first excitation voltage v ex1After that, under the action of the first excitation voltage, according to the voltage sensing signal v s1 Determine the second excitation voltage v s2 , and the voltage sensing signal v s1 and the second excitation voltage v s2 The voltage sensing signal v after the summation is processed s1 and the second excitation voltage v s2 That is v s12 The flux excitation auxiliary unit senses the voltage signal v s1 and the second excitation voltage v s2 After the addition process, the voltage sensing signal v s1 and the second excitation voltage v s2 Transmitted to the DC current zero point detector.

[0052] Furthermore, the low-pass filter LPF in the DC current zero point detector can be used to generate a voltage sensing signal v after the addition process. s1 and the second excitation voltage v s2 Determine the DC voltage signal v dc , and the DC voltage signal v dc Transmitted to the AC current zero point detector.

[0053] In an exemplary embodiment, the low-pass filter is specifically used to process the voltage sensing signal v after the addition process. s1 and the second excitation voltage v s2 Filtering is performed to obtain the DC voltage signal v dc , and the DC voltage signal v dc Transmitted to the AC current zero point detector.

[0054] In an exemplary embodiment, Figure 2 As shown, the magnetic flux excitation auxiliary unit includes a second magnetic core C2, a second winding W2, a unit gain inverter U2, a high pass filter HPF and a second sampling resistor R S2 .

[0055] The second winding W2 is wound on the second magnetic core C2, one end of the second winding W2 is connected to the unit gain inverter U2, and the other end is connected to the high pass filter HPF and the second sampling resistor R S2 One end of the unit gain inverter U2 is connected to the second winding W2, and the other end is connected to the Schmitt trigger U1 and the first winding W1. The second sampling resistor R S2 One end of the high-pass filter HPF is connected to the second winding W2 and the second sampling resistor R S2connected, and the other end is connected to the low pass filter LPF.

[0056] The second magnetic core C2, the second winding W2, the unit gain inverter U2 and the second sampling resistor R S2 , for the first excitation voltage v ex1 Under the action of s1 Determine the second excitation voltage v s2 , and the second excitation voltage v s2 And the voltage sensing signal v s1 The high-pass filter HPF is used to transmit the second excitation voltage v s2 And the voltage sensing signal v s1 The voltage sensing signal v after the addition process is s1 and the second excitation voltage v s2 Transmitted to the DC current zero point detector.

[0057] In an optional embodiment of the present application, the first magnetic core C1 and the second magnetic core C2 have the same parameters, and the first winding W1 and the second winding W2 have the same parameters.

[0058] Optionally, the unity gain inverter U2, also known as a unity gain inverting amplifier or a unity gain buffer, can invert and amplify the input signal, but the amplitude of the output signal is the same as that of the input signal.

[0059] The high pass filter HPF can be used to allow signals above a certain cutoff frequency to pass, while suppressing or attenuating signals below the frequency.

[0060] In some exemplary embodiments, the magnetic flux excitation auxiliary unit receives the voltage sensing signal v transmitted by the DC current zero point detector. s1 and the first excitation voltage v ex1 After that, the second magnetic core C2, the second winding W2, the unit gain inverter U2 and the second sampling resistor R S2 The first excitation voltage v ex1 Under the action of s1 Determine the second excitation voltage v s2 , and the second excitation voltage v s2 And the voltage sensing signal v s1 Transmitted to the high pass filter HPF.

[0061] Further, the high pass filter HPF receives the second excitation voltage v s2 And the voltage sensing signal v s1 After that, the second excitation voltage v s2And the voltage sensing signal v s1 The voltage sensing signal v after the addition process is s1 and the second excitation voltage v s2 Transmitted to the DC current zero point detector, that is, v s12 Transmitted to the DC current zero point detector.

[0062] In an exemplary embodiment, Figure 2 As shown, the AC current zero-point detector includes a third magnetic core C3 and a third winding W3.

[0063] The third winding W3 is wound on the third magnetic core C3 , one end of the third winding W3 is grounded, and the other end is connected to the magnetic flux compensation unit.

[0064] The third magnetic core C3 and the third winding W3 are used to generate a voltage according to the measured current W p Generates an AC voltage signal v ac , and the DC voltage signal v dc And the AC voltage signal v ac Transmitted to the flux compensation unit.

[0065] In some exemplary embodiments, the third magnetic core C3 and the third winding W can be configured according to the measured current W. p Generates an AC voltage signal v ac , and the received DC voltage signal v dc And the generated AC voltage signal v ac Transmitted to the flux compensation unit.

[0066] In an exemplary embodiment, Figure 2 As shown, the flux compensation unit includes a proportional integrator PI, a drive unit PA, a measuring resistor R M , Compensation winding W s .

[0067] One end of the proportional integrator PI is connected to the low-pass filter and the third winding, and the other end is connected to the driving unit PA. One end of the driving unit PA is connected to the proportional integrator PI, and the other end is connected to the compensation winding W. s Connect the compensation winding W s Wound on the first magnetic core and the third magnetic core, the compensation winding W s One end is connected to the driving unit PA, and the other end is connected to the measuring resistor R M Connect the measuring resistor R M One end is grounded and the other end is connected to the compensation winding W s connect;

[0068] The proportional integrator PI, the driving unit PA, the measuring resistor R M and compensation winding W s , used according to the DC voltage signal v dc And the AC voltage signal v ac Determine the compensation current I f , and according to the compensation current I f Determine the measured current W p of magnetic flux.

[0069] The measured current W p And the compensation current I f There is a certain proportional relationship, the compensation magnetic flux generated by the compensation current If is equal to the magnetic flux generated by the measured current IS but opposite in direction, so as to offset and realize zero magnetic flux.

[0070] In some exemplary embodiments, the magnetic flux compensation unit receives a DC voltage signal v transmitted by the AC current zero point detector. dc And the AC voltage signal v ac After that, the proportional integrator PI, the driving unit PA, the measuring resistor R M and compensation winding W s According to the DC voltage signal v dc And the AC voltage signal v ac Determine the compensation current I f , and according to the compensation current I f Determine the measured current W p of magnetic flux.

[0071] In some exemplary embodiments, Figure 2 As shown, the working modes of the fluxgate sensor circuit provided in the present application can be divided into two types. Specifically, when the measured current is a DC current or a low-frequency current, the AC current zero point detector does not work. Under normal working conditions, the excitation current i ex1 The waveform is symmetrical and its average value is zero. Therefore, there is no error signal on PI, the entire circuit is in a balanced state, and IPNP=ISNS, that is, the primary current I S The magnetic flux generated is equal to the secondary current I provided by PA f However, the magnetic flux generated by I S and I f Any imbalance between the generated magnetic fields will cause the excitation current i ex1 The asymmetry of the PA generates an error signal at the input of the PI, which drives the PA to S W2, which is wound on C2 with the same number of turns as W1, is used to offset the excitation flux of C1 in W due to the transformer effect.P and W S U2 is used to obtain the ripple current induced in the ex1 The phase-opposite signal v ex2 To motivate W2.

[0072] A high pass filter can be used to cancel out v S1 The high frequency components are suppressed to suppress the coupling to W through PI and PA. S The modulation ripples of the filter are suppressed as follows: the useful signal of the open-loop self-oscillating fluxgate sensor is extracted by the LPF. In order to obtain a fast response, the time constant of the LPF cannot be too large. However, a small time constant means a fast discharge of the capacitor used in the LPF, which will result in large ripples in the filtered signal. The ripple will serve as an error signal for the PI controller, thus causing a large ripple in the output I f The fundamental and subharmonic ripple currents with the same frequency as the excitation current are generated in the filter. In addition, due to the influence of factors such as aging and temperature drift on the filtered signal, the magnitude of the ripple current may drift, but it is difficult to estimate quantitatively, resulting in unknown errors. In order to effectively filter out the high-frequency components of the useful signal, a high-pass filter HPF is added. If the two signals v S1 and v S2 The high-frequency components of the same amplitude but opposite phase, and then after summing, their high-frequency components will cancel each other out. That is, the resulting signal v S12 will be ripple-free, and due to the high frequency selection function of the HPF, v S1 The DC or low-frequency useful signals will not be attenuated.

[0073] In practical applications, v S1 and v S2 The high-frequency components of the signal cannot be exactly the same, and the time constant of the HPF cannot be infinite. Therefore, the obtained signal v S12 There are still some residual high-frequency components, which can be further attenuated by the following LPF. Then we get an approximately pure useful signal v dc , as the DC error signal of PI. In addition to the time constants of LPF and HPF, v dc The purity depends mainly on v S1 and v S2 The degree of asymmetry between the two excitation currents i ex1 and i ex2 and R S1 and R S2 .

[0074] The working principle of LPF and HPF can be shown as follows Figure 3 As shown, where v S1 and v S2 Respectively represent R S1 and RS2 The voltage signal on the circuit, R1 and C1 form LPF, R2 and C2 form HPF. The output expression of the circuit is:

[0075] , where v dc (s), v S1 (s), v S2 (s) is v dc 、v S1 、v S2 Frequency domain expression of . If R1=R2=R, and v S1 and v S2 The amplitude is the same but the phase is opposite, then R1V S2 (s)+R2V S1 (s)=0, then the transfer function of the circuit is: , where if C2 and C1 exist, the dominant pole is fp≈1 / (4πRC2), and its corresponding time constant is τp≈2RC2. Since the time constant of LPF is τ=RC1, when HPF is added, the time constant increases by about 2C2 / C1 times.

[0076] For medium and high frequency currents, the DC current zero detector does not work. In this case, W3, PI, PA and W wound around C3 S An active AC current transformer, i.e., a magnetic integrator, is constructed. Due to the high gain of the PI, a perfect balance between the primary ampere-turns IPNP and the secondary ampere-turns ISNS will always be established, i.e., a zero flux condition is achieved for both medium and high frequency currents. In practice, the low frequency response of the magnetic integrator can easily be as low as 0.01 Hz, while the high frequency response of the fluxgate sensor circuit can be as high as hundreds of Hz, so for medium frequency currents, the performance of the transducer is dominated by the combined effect of the two, and then a wide bandwidth from DC to high frequency AC is obtained.

[0077] It should be noted that the fluxgate sensor circuit provided in the present application is not only simple in structure and easy to integrate and install, but also suitable for high-precision measurement and can achieve high-sensitivity magnetic field detection. Moreover, since a high-pass filter and a low-pass filter are provided, the interference of temperature drift on the measurement results can be effectively reduced, thereby improving the reliability and stability of the fluxgate sensor.

[0078] In an exemplary embodiment, the present application also provides a fluxgate sensor, which includes the fluxgate sensor circuit described in any of the above embodiments.

[0079] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0080] 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 fluxgate sensor circuit, characterized in that: The fluxgate sensor circuit includes a DC current zero point detector, an AC current zero point detector, a flux compensation unit and a flux excitation auxiliary unit; wherein the DC current zero point detector is connected to the flux excitation auxiliary unit and the flux compensation unit, and the AC current zero point detector is connected to the DC current zero point detector and the flux compensation unit; The DC current zero point detector is used to generate a voltage sensing signal and a first excitation voltage according to the measured current, and transmit the voltage sensing signal and the first excitation voltage to the magnetic flux excitation auxiliary unit; The magnetic flux excitation auxiliary unit is used to determine a DC voltage signal according to the voltage sensing signal under the action of the first excitation voltage, and transmit the DC voltage signal to the AC current zero point detector; The AC current zero point detector is used to generate an AC voltage signal according to the measured current, and transmit the DC voltage signal and the AC voltage signal to the magnetic flux compensation unit; The magnetic flux compensation unit is used to determine a compensation current according to the DC voltage signal and the AC voltage signal, and to determine the magnetic flux of the measured current according to the compensation current.

2. The fluxgate sensor circuit according to claim 1, characterized in that: The flux excitation auxiliary unit is specifically used to determine the second excitation voltage according to the voltage sensing signal under the action of the first excitation voltage, and add the voltage sensing signal and the second excitation voltage, and transmit the voltage sensing signal and the second excitation voltage after the addition to the DC current zero point detector, so that the DC current zero point detector determines the DC voltage signal according to the voltage sensing signal and the second excitation voltage after the addition, and transmits the DC voltage signal to the AC current zero point detector.

3. The fluxgate sensor circuit according to claim 2, characterized in that: The DC current zero point detector includes a first magnetic core, a first winding, a first sampling resistor, a current limiting resistor, a Schmitt trigger and a low-pass filter; wherein the first winding is wound on the first magnetic core, one end of the first winding is connected to the current limiting resistor, and the other end is connected to the Schmitt trigger and the magnetic flux excitation auxiliary unit, one end of the Schmitt trigger is connected to the first sampling resistor, the current limiting resistor and the low-pass filter, and the other end is connected to the magnetic flux excitation auxiliary unit, one end of the first sampling resistor is grounded, and the other end is connected to the low-pass filter, the current limiting resistor and the Schmitt trigger; one end of the current limiting resistor is connected to the first sampling resistor, the low-pass filter and the Schmitt trigger, and the other end is connected to the first winding, one end of the low-pass filter is connected to the first sampling resistor, the current limiting resistor, the Schmitt trigger and the magnetic flux excitation auxiliary unit, and the other end is connected to the magnetic flux compensation unit; The first magnetic core, the first winding, the first sampling resistor, the current limiting resistor and the Schmitt trigger are used to generate the voltage sensing signal and the first excitation voltage according to the measured current, and transmit the voltage sensing signal and the first excitation voltage to the magnetic flux excitation auxiliary unit; The low-pass filter is used to determine the DC voltage signal according to the voltage sensing signal and the second excitation voltage after the addition process, and transmit the DC voltage signal to the AC current zero point detector.

4. The fluxgate sensor circuit according to claim 3, characterized in that: The low-pass filter is specifically used to filter the voltage sensing signal and the second excitation voltage after the addition process to obtain the DC voltage signal, and transmit the DC voltage signal to the AC current zero point detector.

5. The fluxgate sensor circuit according to claim 3, characterized in that: The magnetic flux excitation auxiliary unit includes a second magnetic core, a second winding, a unit gain inverter, a high-pass filter and a second sampling resistor; wherein the second winding is wound on the second magnetic core, one end of the second winding is connected to the unit gain inverter, and the other end is connected to the high-pass filter and the second sampling resistor, one end of the unit gain inverter is connected to the second winding, and the other end is connected to the Schmitt trigger and the first winding, one end of the second sampling resistor is grounded, and the other end is connected to the second winding, one end of the high-pass filter is connected to the second winding and the second sampling resistor, and the other end is connected to the low-pass filter; The second magnetic core, the second winding, the unit gain inverter and the second sampling resistor are used to determine the second excitation voltage according to the voltage sensing signal under the action of the first excitation voltage, and transmit the second excitation voltage and the voltage sensing signal to the high-pass filter; The high-pass filter is used to perform sum processing on the second excitation voltage and the voltage sensing signal, and transmit the voltage sensing signal and the second excitation voltage after the sum processing to the DC current zero point detector.

6. The fluxgate sensor circuit according to claim 5, characterized in that: The AC current zero point detector comprises a third magnetic core and a third winding; wherein the third winding is wound on the third magnetic core, one end of the third winding is grounded, and the other end is connected to the magnetic flux compensation unit; The third magnetic core and the third winding are used to generate an AC voltage signal according to the measured current, and transmit the DC voltage signal and the AC voltage signal to the magnetic flux compensation unit.

7. The fluxgate sensor circuit according to claim 6, characterized in that: The magnetic flux compensation unit includes a proportional integrator, a driving unit, a measuring resistor, and a compensation winding; wherein one end of the proportional integrator is connected to the low-pass filter and the third winding, and the other end is connected to the driving unit; one end of the driving unit is connected to the proportional integrator, and the other end is connected to the compensation winding; the compensation winding is wound on the first magnetic core and the third magnetic core; one end of the compensation winding is connected to the driving unit, and the other end is connected to the measuring resistor; one end of the measuring resistor is grounded, and the other end is connected to the compensation winding; The proportional integrator, the driving unit, the measuring resistor and the compensation winding are used to determine the compensation current according to the DC voltage signal and the AC voltage signal, and to determine the magnetic flux of the measured current according to the compensation current.

8. The fluxgate sensor circuit according to claim 2, characterized in that: The voltage sensing signal and the second excitation voltage are equal in magnitude and opposite in direction.

9. The fluxgate sensor circuit according to claim 5, characterized in that: The first magnetic core and the second magnetic core have the same parameters, and the first winding and the second winding have the same parameters.

10. A fluxgate sensor, characterized in that: The fluxgate sensor comprises the fluxgate sensor circuit according to any one of claims 1 to 9.

Images