Fluxgate sensor, digital sampling system, digital sampling method and controller

Abstract

The application provides a fluxgate sensor, a digital sampling system, a digital sampling method and a controller, and the fluxgate sensor comprises: an excitation source generation circuit, the excitation source generation circuit is provided with an external input interface; the excitation source generation circuit is connected with the controller through the external input interface, and the excitation source generation circuit is also connected with an excitation winding in the fluxgate sensor; the excitation source generation circuit receives an excitation source driving signal output by the controller; the excitation source generation circuit generates a corresponding excitation input signal according to the excitation source driving signal, and outputs the excitation input signal to the excitation winding to excite the excitation winding. In the application, the external input interface and the excitation source generation circuit are arranged in the fluxgate sensor, the excitation source generation circuit generates an excitation signal according to the externally input excitation source driving signal, the adjustment of the excitation signal is realized, the interference of the excitation signal in the sampling process is avoided, and the collection precision is improved.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a fluxgate sensor, a digital sampling system, a digital sampling method, and a controller. Background Technology

[0002] Fluxgate sensors, due to their unique magnetic modulation technology, can achieve superior measurement performance through zero-flux closed-loop control. Specifically, they have fast response time, excellent temperature drift characteristics, and can measure AC and DC signals with a wide measurement range. They are widely used in high-precision, high-performance current measurement applications.

[0003] The earliest fluxgate sensors had a relatively simple single-core structure. However, due to the influence of its excitation winding, the output signal of the single-core modulator contained odd harmonics with large amplitudes. To improve its measurement accuracy, dual-core modulation can be used, ensuring that the excitation signals on the two excitation windings have equal amplitudes but opposite phases at any given time. The odd harmonics in the output signal cancel each other out, while the even harmonics add to each other, thus eliminating the influence of the excitation winding and further improving measurement accuracy. Building on this, to further increase the sensor's measurement bandwidth, an AC core and winding were added to enhance its ability to measure AC signals.

[0004] Although fluxgate magnetization with dual-core windings can theoretically eliminate odd harmonics caused by excitation current and thus reduce sensor sampling errors, for high-sampling-rate, high-precision digital sampling systems, due to their very high data acquisition rates (100 ksps or even Msps), referencing... Figure 1 The excitation signal of a fluxgate sensor is generated by the oscillation signal output from a fluxgate oscillator. This oscillation signal and the corresponding excitation signal are signals with fixed frequencies and phases. The sampling time inevitably overlaps with the sensor's excitation time. At the moment of positive to negative transition in the excitation signal, the disturbance at the transition point will inevitably couple into the secondary output current. Therefore, at high sampling rates, the sampling time will always partially overlap with the sensor's excitation time, resulting in noise components of the excitation frequency in the final acquired data. For micro-current high-precision sampling systems (µA to 10mA level), this noise component is significant and will greatly affect sampling accuracy.

[0005] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0006] The main objective of this invention is to provide a fluxgate sensor, a digital sampling system, a digital sampling method, and a controller, aiming to solve the technical problem of reduced acquisition accuracy caused by noise at the excitation frequency in the prior art.

[0007] To achieve the above objectives, the present invention proposes a fluxgate sensor, which includes: an excitation source generating circuit, wherein the excitation source generating circuit is provided with an external input interface;

[0008] The excitation source generating circuit is connected to the controller through the external input interface, and the excitation source generating circuit is also connected to the excitation winding in the fluxgate sensor.

[0009] The excitation source generating circuit is used to receive the excitation source driving signal output by the controller;

[0010] The excitation source generating circuit is further configured to generate a corresponding excitation input signal based on the excitation source driving signal, and output the excitation input signal to the excitation winding to excite the excitation winding.

[0011] Optionally, the excitation source generating circuit includes: a first and a second diode, a first and a second switching transistor, a first capacitor, and a first and a second resistor;

[0012] Wherein, the anode of the first diode is connected to the positive output terminal of the excitation source drive signal of the controller, the cathode of the first diode is connected to the control terminal of the first switching transistor, the input terminal of the first switching transistor is connected to the positive power supply, the output terminal of the first switching transistor is connected to the first terminal of the first resistor, the second terminal of the first resistor is connected to the first terminal of the first capacitor, and the second terminal of the first capacitor is connected to the excitation winding.

[0013] The anode of the second diode is connected to the negative output terminal of the controller excitation source drive signal, the cathode of the second diode is connected to the control terminal of the second switch, the input terminal of the second switch is connected to the negative power supply, the output terminal of the second switch is connected to the first terminal of the second resistor, and the second terminal of the second resistor is connected to the first terminal of the first capacitor.

[0014] Optionally, the fluxgate sensor further includes: a signal demodulation circuit;

[0015] The signal demodulation circuit is connected to both the controller and the detection winding in the fluxgate sensor.

[0016] The signal demodulation circuit is used to receive the reference signal output by the controller and the excitation output signal output by the detection winding;

[0017] The signal demodulation circuit is further configured to compare the excitation output signal with the reference signal to obtain a phase difference, and feed the phase difference back to the controller so that the controller adjusts the excitation source drive signal according to the phase difference.

[0018] Optionally, the fluxgate sensor further includes: a third diode and a third switching transistor;

[0019] The anode of the third diode is connected to the controller, the cathode of the third diode is connected to the control terminal of the third switch, and both the input and output terminals of the third switch are connected to the signal demodulation circuit.

[0020] In addition, to achieve the above objectives, the present invention also provides a digital sampling system, which includes: a controller, a sampling chip, a signal conditioning circuit, and the fluxgate sensor mentioned above;

[0021] The controller is connected to the sampling chip and the excitation source generation circuit in the fluxgate sensor, respectively. The sampling chip is connected to the fluxgate sensor through a signal conditioning circuit.

[0022] The controller is configured to generate a sampling signal and an excitation source drive signal, and send the sampling signal to the sampling chip and the excitation source drive signal to the excitation source generation circuit; wherein, the sampling frequency of the sampling signal is an integer multiple of the drive frequency of the excitation source drive signal, and the phase difference between the sampling signal and the excitation source drive signal is inversely proportional to the integer multiple;

[0023] The sampling chip is used to, upon receiving the sampling signal, process the current signal output by the fluxgate sensor based on the sampling signal.

[0024] Optionally, the digital sampling system further includes: an overcurrent detection circuit;

[0025] The overcurrent detection circuit is connected to the primary winding of both the controller and the fluxgate sensor.

[0026] The overcurrent detection circuit is used to detect the current signal passing through the primary winding, and outputs an overcurrent signal to the controller when the current value of the current signal is greater than a preset current value.

[0027] The controller is also configured to stop outputting the sampling signal to the sampling chip when it receives the overcurrent signal.

[0028] Optionally, the overcurrent detection circuit includes: a third to a sixth resistor, a fourth switching transistor, and a first comparator;

[0029] In this configuration, the first end of the third resistor is connected to the primary winding; the second end of the third resistor is connected to the first ends of the fourth and fifth resistors; the second end of the fourth resistor is connected to the positive input of the first comparator; the second end of the fifth resistor is grounded; the inverting input of the first comparator is connected to a preset current source; the output of the first comparator is connected to the control terminal of the fourth switch; the input of the fourth switch is connected to the first end of the sixth resistor; the output of the fourth switch is grounded; and the second end of the sixth resistor is connected to the controller.

[0030] Furthermore, to achieve the above objectives, the present invention also provides a digital sampling method, the digital sampling method comprising:

[0031] When sampling is initiated, a sampling signal and an excitation source drive signal are generated; wherein, the sampling frequency of the sampling signal is an integer multiple of the drive frequency of the excitation source drive signal, and the phase difference between the sampling signal and the excitation source drive signal is inversely proportional to the integer multiple;

[0032] The excitation source drive signal is output to the fluxgate sensor so that the fluxgate sensor generates a corresponding excitation signal to excite the excitation winding.

[0033] The sampling signal is output to the sampling chip so that the sampling chip can collect the current parameters output by the fluxgate sensor based on the sampling signal.

[0034] Optionally, after the step of outputting the sampling signal to the sampling chip so that the sampling chip can acquire the current parameters output by the fluxgate sensor based on the sampling signal, the method further includes:

[0035] A reference signal is generated based on the excitation source drive signal;

[0036] The reference signal is output to the signal demodulation circuit in the fluxgate sensor so that the signal demodulation circuit compares the second harmonic signal with the reference signal and feeds back the phase difference; the second harmonic signal is the signal after demodulation by superimposing the external current magnetic field signal output by the detection winding and the excitation signal.

[0037] The excitation source drive signal is adjusted according to the phase difference;

[0038] Detect the current signal passing through the primary winding;

[0039] When the current value of the current signal is greater than the preset current value, the connection between the device under test and the fluxgate sensor is disconnected.

[0040] In addition, to achieve the above objectives, the present invention also provides a controller, which is connected to a sampling chip and a fluxgate sensor;

[0041] The controller is used to implement the digital sampling method.

[0042] This invention provides a fluxgate sensor, a digital sampling system, a digital sampling method, and a controller. The fluxgate sensor includes an excitation source generating circuit with an external input interface. The excitation source generating circuit is connected to a controller via the external input interface and is also connected to an excitation winding within the fluxgate sensor. The excitation source generating circuit receives an excitation source drive signal output by the controller. It also generates a corresponding excitation input signal based on the excitation source drive signal and outputs the excitation input signal to the excitation winding to excite it. In this invention, by incorporating an external input interface and an excitation source generating circuit within the fluxgate sensor, and utilizing the excitation source generating circuit to generate an excitation signal based on the externally input excitation source drive signal, the excitation signal can be adjusted, avoiding interference during sampling and improving acquisition accuracy. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the structure of a fluxgate sensor in the prior art;

[0045] Figure 2 This is a schematic diagram of the structure of the first embodiment of the fluxgate sensor proposed in this invention;

[0046] Figure 3 This is a schematic diagram of the sampling time and excitation time in a digital sampling system in the prior art;

[0047] Figure 4 This is a circuit block diagram showing the interface connection of the controller in this invention;

[0048] Figure 5 This is a schematic diagram of the structure of the digital sampling system proposed in this invention;

[0049] Figure 6 This is a schematic diagram showing the sampling time and excitation time of the digital sampling system proposed in this invention;

[0050] Figure 7 This is a flowchart illustrating the first embodiment of the digital sampling method of the present invention;

[0051] Figure 8 This is a flowchart illustrating the second embodiment of the digital sampling method of the present invention.

[0052] Explanation of icon numbers:

[0053]

[0054]

[0055] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0056] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0058] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0059] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, the user should consider such a combination of technical solutions to be non-existent and not within the scope of protection claimed by this invention.

[0060] Reference Figure 2 , Figure 2 This is a schematic diagram of the first embodiment of the fluxgate sensor proposed in this invention. Based on Figure 2 The first embodiment of the fluxgate sensor of the present invention is presented.

[0061] In this embodiment, the fluxgate sensor includes: an excitation source generating circuit 10, which has an external input interface;

[0062] The excitation source generating circuit 10 is connected to the controller through the external input interface, and the excitation source generating circuit 10 is also connected to the excitation winding in the fluxgate sensor.

[0063] It should be understood that, in Figure 1 In a fluxgate magnetometer, a typical structure comprises a fixed-frequency oscillator, an excitation source power amplifier, an excitation winding W1, a primary winding W2, a detection winding W3, a compensation winding W4, signal demodulation, integration, and power amplification components. The oscillator outputs a fixed-frequency oscillation signal. (Refer to...) Figure 3 When a fluxgate sensor collects current signals, the initiation sampling time of the sampling signal may occur simultaneously with the rising edge of the excitation signal generated by the oscillation signal output by the oscillator. At this time, the collected current signal will be interfered with by the rising edge of the excitation signal, resulting in a significant reduction in the acquisition accuracy.

[0064] It should be noted that, in this embodiment, the excitation source generating circuit 10 is a circuit used to generate an excitation signal. The signal frequency of the driving signal output by the excitation source generating circuit 10 can be adjusted within a certain range.

[0065] The excitation source generating circuit 10 includes an external input interface 101, through which signals input from the controller can be directly received. When the frequency or phase of the signal input from the controller changes, the frequency or phase of the excitation signal generated by the excitation source generating circuit 10 will change accordingly.

[0066] In a specific implementation, the excitation source generating circuit 10 can receive the excitation source driving signal output by the controller through the external input interface 101; then generate a corresponding excitation input signal according to the excitation source driving signal, and output the excitation input signal to the excitation winding to excite the excitation winding.

[0067] The excitation source drive signal is generated by the controller. The sampling frequency is an integer multiple of the driving frequency of the excitation source drive signal and the sampling frequency of the sampling signal. The phase difference between the excitation source drive signal and the sampling signal is inversely proportional to the integer multiple. The excitation source drive signal can be used to drive the excitation source generation circuit 10, causing the excitation source generation circuit 10 to output a corresponding excitation signal. Both the excitation source drive signal and the excitation signal are PWM signals. The excitation signal and the excitation source drive signal have the same frequency and phase.

[0068] This embodiment provides a fluxgate sensor, which includes: an excitation source generating circuit with an external input interface; wherein the excitation source generating circuit is connected to a controller through the external input interface, and is also connected to an excitation winding within the fluxgate sensor; the excitation source generating circuit is used to receive an excitation source drive signal output by the controller; the excitation source generating circuit is also used to generate a corresponding excitation input signal based on the excitation source drive signal, and output the excitation input signal to the excitation winding to excite the excitation winding. In this embodiment, by setting an external input interface and an excitation source generating circuit within the fluxgate sensor, and utilizing the excitation source generating circuit to generate an excitation signal based on the externally input excitation source drive signal, the excitation signal can be adjusted, avoiding interference with the excitation signal during sampling, thereby improving the acquisition accuracy.

[0069] Based on the first embodiment of the fluxgate sensor described above, a second embodiment of the fluxgate sensor of the present invention is proposed.

[0070] Reference Figure 4 In this embodiment, the excitation source generating circuit 10 includes: a first and a second diode, a first and a second switching transistor, a first capacitor C1, and a first and a second resistor;

[0071] Wherein, the anode of the first diode D1 is connected to the positive output terminal PWM+ of the controller excitation source drive signal, the cathode of the first diode D1 is connected to the control terminal of the first switch Q1, the input terminal of the first switch Q1 is connected to the positive power supply +VCC, the output terminal of the first switch Q1 is connected to the first terminal of the first resistor R1, the second terminal of the first resistor R1 is connected to the first terminal of the first capacitor C1, and the second terminal of the first capacitor C1 is connected to the primary winding.

[0072] The anode of the second diode D1 is connected to the negative output terminal PWM- of the controller excitation source drive signal, the cathode of the second diode D1 is connected to the control terminal of the second switch Q2, the input terminal of the second switch Q2 is connected to the negative power supply -VCC, the output terminal of the second switch Q2 is connected to the first terminal of the second resistor R2, and the second terminal of the second resistor R2 is connected to the first terminal of the first capacitor C1.

[0073] It should be understood that the excitation signal received by the excitation winding needs to include alternating forward and reverse voltages to generate a change in magnetic flux on the excitation winding. Therefore, both forward and reverse voltages are required in the process of generating the excitation signal.

[0074] It should be noted that the positive power supply +VCC is used to output a positive voltage, and the negative power supply -VCC is used to output a negative voltage. The controller can output PWM signals with opposite phases through two different interfaces, thereby controlling the output voltage of the positive power supply +VCC and the negative power supply -VCC at corresponding times. The first switch Q1 and the second switch Q2 are switching devices with control terminals, such as controllable switches, transistors, MOSFETs, etc.

[0075] In practical implementation, the controller can output a PWM signal from the positive output terminal and a PWM signal with the same frequency and amplitude but completely opposite phase from the negative output terminal. When the first PWM signal is high, the first switch Q1 can be turned on, at which time the positive power supply +VCC can output a positive voltage to the excitation winding through the first switch Q1 and the first resistor R1. When the second PWM signal is high, the second switch Q2 can be turned on, at which time the negative power supply -VCC can output a negative voltage to the excitation winding through the second switch Q2 and the second resistor R2.

[0076] In addition, the first diode D1 and the second diode D2 can prevent the positive or negative voltage output from the positive power supply +VCC or the negative power supply -VCC from flowing back into the controller, thus protecting the controller.

[0077] In addition, refer to Figure 1 and Figure 2 In this embodiment, the fluxgate sensor further includes a signal demodulation circuit;

[0078] The signal demodulation circuit is connected to both the controller and the detection winding W3 in the fluxgate sensor.

[0079] It should be understood that the magnetic field signal output by the detection winding W3 needs to be demodulated to obtain the corresponding current signal. The signal demodulation circuit is the circuit that demodulates the magnetic field signal. Of course, in this embodiment, the signal demodulation circuit is also connected to a PI integrator and a power amplification device to output a more accurate current signal.

[0080] It should be noted that when the fluxgate sensor collects the current signal, due to electromagnetic changes in the primary winding W2, excitation winding W1, etc., there may be a certain phase difference between the actual current signal demodulated by the signal demodulation circuit and the theoretically output current signal, which may result in the collected current signal being inaccurate.

[0081] It needs to be emphasized that, Figure 1 The signal demodulation circuit in the [reference] is used to demodulate the excitation output signal from the detection winding W3, and does not need to establish a connection with the controller. In this embodiment, the signal demodulation circuit is... Figure 2 The signal demodulation circuit in the sensor also establishes a connection with the controller, allowing it to receive a reference signal input from the controller. This reference signal can be used to determine whether the phase of the excitation output signal from the detection winding is affected by interference. This reference signal can be a PWM signal corresponding to a double-frequency excitation source drive signal.

[0082] To avoid phase deviation of the current signal, in this embodiment, the controller can also output a reference signal to the signal demodulation circuit. The signal demodulation circuit superimposes and demodulates the external current magnetic field signal output by the detection winding with the excitation signal to obtain a second harmonic signal. Then, it compares the second harmonic signal with the reference signal to obtain the phase difference between the second harmonic signal and the reference signal, and feeds the phase difference back to the controller. The controller can also adjust the excitation source drive signal according to the phase difference, so that the second harmonic signal output by the signal demodulation circuit is in phase with the excitation signal.

[0083] The second harmonic signal is obtained by superimposing the external current magnetic field signal and the excitation signal. This second harmonic signal is then integrated by a PI converter and amplified to obtain the acquired current signal. The reference signal is output by the controller to determine whether the demodulated second harmonic signal has undergone a phase change. This reference signal can be a double-frequency PWM signal of the excitation source drive signal.

[0084] The fluxgate sensor also includes: a third diode D3 and a third switch Q3;

[0085] The anode of the third diode D3 is connected to the controller, the cathode of the third diode D3 is connected to the control terminal of the third switch Q3, and both the input and output terminals of the third switch Q3 are connected to the signal demodulation circuit.

[0086] Reference Figure 4 The controller can output a PWM signal through the reference signal output terminal CLK-IN to control the on / off state of the third switch Q3, thereby inputting the frequency-doubled PWM signal to the demodulation circuit as a reference signal.

[0087] In this embodiment, by incorporating an external input interface and an excitation source generation circuit within the fluxgate sensor, the excitation source generation circuit generates an excitation signal based on the externally input excitation source drive signal. This adjustment of the excitation signal avoids interference during sampling, thereby improving acquisition accuracy. Furthermore, by connecting the signal demodulation circuit to the controller, the phase difference between the reference signal and the second harmonic can be used to adjust the excitation source drive signal, further accurately preventing interference during sampling.

[0088] To achieve the above objectives, the present invention also provides a digital sampling system, which includes: a controller 400, a sampling chip 300, a signal conditioning circuit 200, and the fluxgate sensor 100.

[0089] The controller 400 is connected to the sampling chip 300 and the excitation source generating circuit 10 in the fluxgate sensor 100, respectively. The sampling chip 300 is connected to the fluxgate sensor 100 through the signal conditioning circuit 200.

[0090] The controller 400 is used to generate a sampling signal and an excitation source drive signal, and sends the sampling signal to the sampling chip 300 and the excitation source drive signal to the excitation source generation circuit; wherein, the sampling frequency of the sampling signal is an integer multiple of the drive frequency of the excitation source drive signal, and the phase difference between the sampling signal and the excitation source drive signal is inversely proportional to the integer multiple;

[0091] The sampling chip 300 is used to, upon receiving the sampling signal, process the current signal output by the fluxgate sensor based on the sampling signal.

[0092] It should be noted that the controller 400 is a device used to control the signal acquisition and excitation processes of the fluxgate sensor 100. The controller 400 can be composed of an FPGA or other control chips with similar functions. The excitation source generation circuit 10 is a circuit used to generate an excitation source. This excitation source generation circuit 10 can output different excitation signals depending on the input drive signal. The excitation source generation circuit 10 can be connected to the controller 400 through an excitation source control interface to receive the drive signal output by the controller 400. The frequency of the drive signal output by the excitation source generation circuit 10 can be adjusted within a certain range. The sampling chip 300 is a chip used to sample the current signal output by the fluxgate sensor 100. The sampling chip 300 can be an ADC sampling chip. At the moment corresponding to the sampling signal, the sampling chip 300 can output the current signal conditioned by the signal conditioning circuit 200, completing the current sampling process. The signal conditioning circuit 200 is used to condition the current signal output by the fluxgate sensor 100 into a corresponding voltage signal.

[0093] In a specific implementation, the controller 400 can generate a sampling signal and an excitation source drive signal when sampling is initiated. The sampling frequency of the sampling signal is an integer multiple of the drive frequency of the excitation source drive signal, and the phase difference between the sampling signal and the excitation source drive signal is inversely proportional to the integer multiple. The sampling signal is then sent to the sampling chip 300, and simultaneously the excitation source drive signal is sent to the excitation source generation circuit 10. The excitation source generation circuit 10 can generate a corresponding excitation signal based on the excitation source drive signal and output the excitation signal to the excitation winding to excite the excitation winding. When the sampling signal is received, the sampling chip 300 can collect the current parameters output by the fluxgate sensor. At this time, the sampling signal and the excitation signal can be referenced. Figure 6 There is no mutual interference between the two.

[0094] The sampling signal is used to control the fluxgate sensor 100 to collect current. This sampling signal is a high-frequency PWM signal. To avoid simultaneous triggering of the excitation signal and the sampling signal, the frequency and phase of the excitation signal and the sampling signal can be limited. During the generation of the sampling signal and the excitation source drive signal, one signal can be generated first, and then the frequency and phase of the other signal can be adjusted based on the first generated signal, thereby avoiding interference from the excitation signal to the sampling signal.

[0095] This embodiment provides a digital sampling system, which includes: a controller 400, a fluxgate sensor 100, a signal conditioning circuit 200, and a sampling chip 300. The controller 400 is connected to the sampling chip 300 and the excitation source generation circuit within the fluxgate sensor 100. The sampling chip is connected to the fluxgate sensor 100 through the signal conditioning circuit 200. The controller 400 is used to generate a sampling signal and an excitation source drive signal when sampling is initiated, and sends the sampling signal to the sampling chip and the excitation source drive signal to the excitation source generation circuit. The sampling frequency of the sampling signal is an integer multiple of the drive frequency of the excitation source drive signal, and the phase difference between the sampling signal and the excitation source drive signal is inversely proportional to the integer multiple. The sampling chip is used to, upon receiving the sampling signal, generate a current signal output by the fluxgate sensor based on the sampling signal. In this invention, by limiting the frequency and phase relationship between the sampling signal and the excitation source driving signal when generating the sampling signal and the excitation source driving signal, there is no interference from the excitation signal at each sampling moment in the sampling process, thereby improving the acquisition accuracy.

[0096] Based on the first embodiment of the digital sampling system described above, a second embodiment of the digital sampling system of the present invention is proposed.

[0097] Reference Figure 4 and Figure 5 In this embodiment, the digital sampling system further includes: an overcurrent detection circuit 500;

[0098] The overcurrent detection circuit 500 is connected to the controller 400 and the primary winding W2 of the fluxgate sensor 100.

[0099] It should be understood that during the current acquisition process, the fluxgate sensor 100 may experience excessive current input to the primary winding, which could damage the sensor due to the current flow within the fluxgate sensor 100.

[0100] Therefore, when the fluxgate sensor 100 collects current, it can also collect the current inside the fluxgate sensor 100 to ensure that the internal current of the sensor is not too large and will damage the sensor. The overcurrent detection circuit 500 is used to confirm the current value inside the fluxgate sensor 100. When the current value is too large, the process detection circuit can output a corresponding overcurrent signal to indicate that the sensor is in an overcurrent state.

[0101] In a specific implementation, the overcurrent detection circuit 500 can detect the current signal passing through the primary winding W2, and when the current value of the current signal is greater than a preset current value, it outputs an overcurrent signal to the controller 400; when the controller 400 receives the overcurrent signal, it outputs a sampling cutoff signal to the sampling chip; when the sampling chip receives the sampling cutoff signal, it disconnects the connection between the device under test and the primary winding W2.

[0102] In addition, the overcurrent detection circuit 500 can also directly output the overcurrent signal to control the indicator light on the fluxgate sensor 100 to light up, thereby indicating that the fluxgate sensor 100 is in an overcurrent state.

[0103] The overcurrent signal is the signal output by the overcurrent detection circuit 500 when the sensor is in an overcurrent state. The preset current value is the maximum current that the fluxgate sensor 100 can pass through. The sampling cutoff signal is a signal used to control the primary winding W2 of the fluxgate sensor 100 to disconnect from the device under test.

[0104] Reference Figure 4 In this embodiment, the overcurrent detection circuit 500 includes: a third to a sixth resistor, a fourth switch Q4, and a first comparator A1;

[0105] In this circuit, the first end of the third resistor R3 is connected to the primary winding W2; the second end of the third resistor R3 is connected to the first ends of the fourth resistor R4 and the fifth resistor R5; the second end of the fourth resistor R4 is connected to the positive input of the first comparator A1; the second end of the fifth resistor R5 is grounded to GND; the inverting input of the first comparator A1 is connected to a preset current source Vref; the output of the first comparator A1 is connected to the control terminal of the fourth switch Q4; the input of the fourth switch Q4 is connected to the first end of the sixth resistor R6; the output of the fourth switch Q4 is grounded to GND; and the second end of the sixth resistor R6 is connected to the controller 400.

[0106] Reference Figure 4 The preset current source is a pre-set current source used to provide a preset current value. After the current in the fluxgate sensor 100 is input to the positive input terminal of the first comparator A1 through the third to sixth resistors, the first comparator A1 compares the current signal value with the preset current value. When the current signal value is greater than the preset current value, the first comparator A1 outputs a low-level signal, the fourth switch Q4 is turned off, and the overcurrent terminal STATU of the controller 400 is not directly grounded and is in a high-impedance state. When the current signal value is less than the preset current value, the fourth switch Q4 is turned on, and the overcurrent terminal of the controller 400 is grounded through the sixth resistor R6 and is in a low-level state. The controller 400 can determine whether the fluxgate sensor 100 is in an overcurrent state based on the state of this overcurrent pin, and control the fluxgate sensor 100 to stop working when it is in an overcurrent state. The controller 400 can also output a sampling signal or a sampling cutoff signal through the sampling signal output terminal ADC.

[0107] In addition, refer to Figure 7 , Figure 7 This is a flowchart illustrating the first embodiment of the digital sampling method of the present invention; to achieve the above objective, the present invention also provides a digital sampling method, the digital sampling method comprising:

[0108] Step S10: When sampling is started, a sampling signal and an excitation source drive signal are generated; wherein, the sampling frequency of the sampling signal is an integer multiple of the drive frequency of the excitation source drive signal, and the phase difference between the sampling signal and the excitation source drive signal is inversely proportional to the integer multiple;

[0109] Step S20: Output the excitation source drive signal to the fluxgate sensor so that the fluxgate sensor generates a corresponding excitation signal to excite the excitation winding;

[0110] Step S30: Output the sampling signal to the sampling chip so that the sampling chip can collect the current parameters output by the fluxgate sensor according to the sampling signal.

[0111] It should be understood that fluxgate sensors typically consist of a fixed-frequency oscillator, an excitation source power amplifier, windings, signal demodulation, integration, and power amplification structures. The oscillator outputs a fixed-frequency PWM signal. When a fluxgate sensor acquires a current signal, the initiation sampling moment of the sampling signal may occur simultaneously with the rising edge of the PWM signal output by the oscillator. In this case, the acquired current signal will be interfered with by the rising edge of the PWM signal, resulting in a significant reduction in acquisition accuracy.

[0112] It should be noted that, in this embodiment, a controller can be used as the execution entity. The controller is a device used to control the signal acquisition, excitation, and other processes of the fluxgate sensor. This controller can be composed of an FPGA or other control chips with similar functions.

[0113] The excitation source generating circuit within the fluxgate sensor is used to generate the excitation source. This circuit can output different excitation signals depending on the input drive signal. The excitation source generating circuit can be connected to a controller via an excitation source control interface to receive drive signals output by the controller. The frequency of the drive signal output by the excitation source generating circuit can be adjusted within a certain range. The fluxgate sensor may include a primary winding, a magnetizing winding, a detection winding, a compensation winding, and an iron core. The sampling chip is a circuit used to acquire the current signal from the fluxgate sensor.

[0114] In a specific implementation, the controller can generate a sampling signal and an excitation source drive signal when sampling is initiated. The sampling frequency of the sampling signal is an integer multiple of the drive frequency of the excitation source drive signal, and the phase difference between the sampling signal and the excitation source drive signal is inversely proportional to the integer multiple. Then, the sampling signal is sent to the sampling chip, and the excitation source drive signal is sent to the excitation source generation circuit. The excitation source generation circuit can generate a corresponding excitation signal according to the excitation source drive signal and output the excitation signal to the excitation winding to excite the excitation winding. When the sampling signal is received, the sampling chip can collect the current parameters output by the fluxgate sensor.

[0115] The sampling signal is used to control the acquisition of the current output by the fluxgate sensor. This sampling signal is a high-frequency PWM signal. The excitation source drive signal can be used to drive the excitation source generation circuit 10, causing it to output a corresponding excitation signal. To avoid simultaneous triggering of the excitation signal and the sampling signal, the frequency and phase of both signals can be limited. During the generation of the sampling signal and the excitation source drive signal, one signal can be generated first, and then the frequency and phase of the other signal can be adjusted based on the first generated signal, thereby preventing the excitation signal from interfering with the sampling signal.

[0116] The process of generating a sampling signal and an excitation source drive signal upon initiating sampling specifically includes: generating a sampling signal according to sampling requirements upon initiation; acquiring an initial excitation source drive signal; and adjusting the initial excitation source drive signal according to the frequency and phase of the sampling signal to generate the next excitation source drive signal.

[0117] It should be understood that sampling requirements are the conditions for setting the current sampling of the fluxgate sensor. These sampling requirements may include sampling frequency, sampling time, etc. When determining the sampling requirements, the controller can generate a corresponding sampling signal based on these requirements.

[0118] It should be noted that the initial excitation source drive signal is an unadjusted drive signal in terms of frequency and phase. Interference may exist between the excitation signal generated by the excitation source generation circuit and the sampled signal from this initial excitation source drive signal.

[0119] In practice, after confirming the sampling signal, the initial excitation source drive signal can be adjusted based on the sampling signal to generate the corresponding excitation source drive signal. Alternatively, if the excitation source drive signal is determined, it can also be used as a reference to adjust and generate the corresponding sampling signal. Since the adjustments to both the excitation source drive signal and the sampling signal are within a relatively small range, the adjustment method can be determined based on the specific adjustment range.

[0120] This embodiment provides a digital sampling method, which includes: generating a sampling signal and an excitation source drive signal upon initiation of sampling; wherein the sampling frequency of the sampling signal is an integer multiple of the drive frequency of the excitation source drive signal, and the phase difference between the sampling signal and the excitation source drive signal is inversely proportional to the integer multiple; outputting the excitation source drive signal to a fluxgate sensor to generate a corresponding excitation signal to excite the excitation winding; and outputting the sampling signal to a sampling chip to acquire the current parameters output by the fluxgate sensor based on the sampling signal. In this invention, by limiting the frequency and phase relationship of the sampling signal and the excitation source drive signal during generation, interference from the excitation signal is eliminated at each sampling moment during the sampling process, thereby improving the acquisition accuracy.

[0121] In addition, refer to Figure 8 , Figure 8 This is a flowchart illustrating the second embodiment of the digital sampling method of the present invention; based on the first embodiment described above, a second embodiment of the digital sampling method of the present invention is proposed.

[0122] In this embodiment, after step S30, the method further includes:

[0123] Step S40: Generate a reference signal based on the excitation source drive signal;

[0124] Step S50: Output the reference signal to the signal demodulation circuit in the fluxgate sensor so that the signal demodulation circuit compares the second harmonic signal with the reference signal and feeds back the phase difference;

[0125] Step S60: Adjust the excitation source drive signal according to the phase difference.

[0126] It should be understood that the magnetic field signal output by the detection winding needs to be demodulated to obtain the corresponding current signal. The signal demodulation circuit is the circuit that demodulates the magnetic field signal. Of course, in this embodiment, the signal demodulation circuit is also connected to a PI integrator and a power amplification device to output a more accurate current signal.

[0127] It should be noted that when the fluxgate sensor collects the current signal, due to electromagnetic changes in the primary winding, excitation winding, etc., there may be a certain phase difference between the actual current signal demodulated by the signal demodulation circuit and the theoretically output current signal, which may result in the collected current signal being inaccurate.

[0128] To avoid phase deviation of the current signal, in this embodiment, the controller can also output a reference signal to the signal demodulation circuit. The signal demodulation circuit superimposes and demodulates the external current magnetic field signal output by the detection winding with the excitation signal to obtain a second harmonic signal. Then, it compares the second harmonic signal with the reference signal to obtain the phase difference between the second harmonic signal and the reference signal, and feeds the phase difference back to the controller. The controller can also adjust the excitation source drive signal according to the phase difference, so that the second harmonic signal output by the signal demodulation circuit is in phase with the excitation signal.

[0129] The second harmonic signal is obtained by superimposing the external current magnetic field signal and the excitation signal. This second harmonic signal is then integrated by a PI converter and amplified to obtain the acquired current signal. The reference signal is output by the controller to determine whether the demodulated second harmonic signal has undergone a phase change. This reference signal can be a double-frequency PWM signal of the excitation source drive signal.

[0130] In this embodiment, step S60 is followed by:

[0131] Step S70: Detect the current signal passing through the primary winding.

[0132] Step S80: When the current value of the current signal is greater than the preset current value, disconnect the connection between the device under test and the fluxgate sensor.

[0133] It should be understood that during the current acquisition process of the fluxgate sensor, there may be a situation where the current input to the primary winding is too large, which may cause excessive current in the fluxgate sensor and damage the sensor.

[0134] Therefore, when the fluxgate sensor collects current, it can also collect the current inside the fluxgate sensor to ensure that the internal current is not too high and could damage the sensor. The overcurrent detection circuit is used to confirm the current value inside the fluxgate sensor. When the current value is too high, the detection circuit can output a corresponding overcurrent signal, thus indicating that the sensor is in an overcurrent state.

[0135] In a specific implementation, the overcurrent detection circuit can detect the current signal passing through the primary winding, and when the current value of the current signal is greater than a preset current value, it outputs an overcurrent signal to the controller; when the controller receives the overcurrent signal, it outputs a sampling cutoff signal to the sampling chip; when the sampling chip receives the sampling cutoff signal, it disconnects the connection between the device under test and the primary winding.

[0136] In addition, the overcurrent detection circuit can also directly output the overcurrent signal to control the indicator light on the fluxgate sensor to illuminate, thereby indicating that the fluxgate sensor is in an overcurrent state.

[0137] The overcurrent signal is the signal output by the overcurrent detection circuit when the sensor is in an overcurrent state. The preset current value is the maximum current that the fluxgate sensor can pass through. The sampling cutoff signal is used to control the primary winding inside the sensor to disconnect from the device under test.

[0138] In addition, to achieve the above objectives, the present invention also provides a controller, which is connected to a sampling chip and a fluxgate sensor;

[0139] The controller is used to implement the digital sampling method. Since the above digital sampling methods all use the controller as the execution subject, this controller can implement the above digital sampling methods and has the corresponding beneficial effects of the above digital sampling methods.

[0140] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A fluxgate sensor, characterized in that, The fluxgate sensor includes: an excitation source generating circuit, wherein the excitation source generating circuit is provided with an external input interface; The excitation source generating circuit is connected to the controller through the external input interface, and the excitation source generating circuit is also connected to the excitation winding in the fluxgate sensor. The excitation source generating circuit is used to receive the excitation source driving signal output by the controller; The excitation source generating circuit is also used to generate a corresponding excitation input signal according to the excitation source driving signal, and output the excitation input signal to the excitation winding to excite the excitation winding; The excitation source drive signal is generated by the controller. The drive frequency of the excitation source drive signal is an integer multiple of the sampling frequency of the sampling signal generated by the controller. The phase difference between the excitation source drive signal and the sampling signal is inversely proportional to the integer multiple. Both the excitation source drive signal and the excitation input signal output by the fluxgate sensor are PWM signals. The frequency and phase of the excitation input signal are the same as those of the excitation source drive signal.

2. The fluxgate sensor as described in claim 1, characterized in that, The excitation source generating circuit includes: first and second diodes, first and second switching transistors, a first capacitor, and first and second resistors; Wherein, the anode of the first diode is connected to the positive output terminal of the excitation source drive signal of the controller, the cathode of the first diode is connected to the control terminal of the first switching transistor, the input terminal of the first switching transistor is connected to the positive power supply, the output terminal of the first switching transistor is connected to the first terminal of the first resistor, the second terminal of the first resistor is connected to the first terminal of the first capacitor, and the second terminal of the first capacitor is connected to the excitation winding. The anode of the second diode is connected to the negative output terminal of the controller excitation source drive signal, the cathode of the second diode is connected to the control terminal of the second switch, the input terminal of the second switch is connected to the negative power supply, the output terminal of the second switch is connected to the first terminal of the second resistor, and the second terminal of the second resistor is connected to the first terminal of the first capacitor.

3. The fluxgate sensor as described in claim 1, characterized in that, The fluxgate sensor also includes: a signal demodulation circuit; The signal demodulation circuit is connected to both the controller and the detection winding in the fluxgate sensor. The signal demodulation circuit is used to receive the reference signal output by the controller and the excitation output signal output by the detection winding; The signal demodulation circuit is further configured to compare the excitation output signal with the reference signal to obtain a phase difference, and feed the phase difference back to the controller so that the controller adjusts the excitation source drive signal according to the phase difference.

4. The fluxgate sensor as described in claim 3, characterized in that, The fluxgate sensor also includes: a third diode and a third switching transistor; The anode of the third diode is connected to the controller, the cathode of the third diode is connected to the control terminal of the third switch, and both the input and output terminals of the third switch are connected to the signal demodulation circuit.

5. A digital sampling system, characterized in that, The digital sampling system includes: a controller, a sampling chip, a signal conditioning circuit, and a fluxgate sensor as described in any one of claims 1-4; The controller is connected to the sampling chip and the excitation source generation circuit in the fluxgate sensor, respectively. The sampling chip is connected to the fluxgate sensor through a signal conditioning circuit. The controller is configured to generate a sampling signal and an excitation source drive signal, and send the sampling signal to the sampling chip and the excitation source drive signal to the excitation source generation circuit; wherein, the sampling frequency of the sampling signal is an integer multiple of the drive frequency of the excitation source drive signal, and the phase difference between the sampling signal and the excitation source drive signal is inversely proportional to the integer multiple; The sampling chip is used to, upon receiving the sampling signal, process the current signal output by the fluxgate sensor based on the sampling signal.

6. The digital sampling system as described in claim 5, characterized in that, The digital sampling system also includes: an overcurrent detection circuit; The overcurrent detection circuit is connected to the primary winding of both the controller and the fluxgate sensor. The overcurrent detection circuit is used to detect the current signal passing through the primary winding, and outputs an overcurrent signal to the controller when the current value of the current signal is greater than a preset current value. The controller is also configured to stop outputting the sampling signal to the sampling chip when it receives the overcurrent signal.

7. The digital sampling system as described in claim 6, characterized in that, The overcurrent detection circuit includes: third to sixth resistors, a fourth switching transistor, and a first comparator; In this configuration, the first end of the third resistor is connected to the primary winding; the second end of the third resistor is connected to the first ends of the fourth and fifth resistors; the second end of the fourth resistor is connected to the positive input of the first comparator; the second end of the fifth resistor is grounded; the inverting input of the first comparator is connected to a preset current source; the output of the first comparator is connected to the control terminal of the fourth switch; the input of the fourth switch is connected to the first end of the sixth resistor; the output of the fourth switch is grounded; and the second end of the sixth resistor is connected to the controller.

8. A digital sampling method, applied to a controller in a digital sampling system, characterized in that, The digital sampling method includes: When sampling is initiated, a sampling signal and an excitation source drive signal are generated; wherein, the sampling frequency of the sampling signal is an integer multiple of the drive frequency of the excitation source drive signal, and the phase difference between the sampling signal and the excitation source drive signal is inversely proportional to the integer multiple; The excitation source drive signal is output to the fluxgate sensor, so that the fluxgate sensor generates a corresponding excitation input signal to excite the excitation winding; both the excitation source drive signal and the excitation input signal output by the fluxgate sensor are PWM signals; the frequency and phase of the excitation input signal are the same as those of the excitation source drive signal. The sampling signal is output to the sampling chip so that the sampling chip can collect the current parameters output by the fluxgate sensor based on the sampling signal.

9. The digital sampling method as described in claim 8, characterized in that, After the step of outputting the sampling signal to the sampling chip so that the sampling chip can acquire the current parameters output by the fluxgate sensor based on the sampling signal, the method further includes: A reference signal is generated based on the excitation source drive signal; The reference signal is output to the signal demodulation circuit inside the fluxgate sensor, so that the signal demodulation circuit compares the second harmonic signal with the reference signal and feeds back the phase difference; the second harmonic signal is the signal after demodulation by superimposing the external current magnetic field signal output by the detection winding and the excitation input signal. The excitation source drive signal is adjusted according to the phase difference; Detect the current signal passing through the primary winding; When the current value of the current signal is greater than the preset current value, the connection between the device under test and the fluxgate sensor is disconnected.

10. A controller, characterized in that, The controller is connected to the sampling chip and the fluxgate sensor; The controller is used to implement the digital sampling method according to any one of claims 8 to 9.

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