Zero-flux current sensor with self-recovery capability

Abstract

The utility model relates to a zero-flux current sensor with self-recovery capability. The zero-flux current sensor comprises a zero-flux current sensor body which comprises a current sensor main body and a main feedback circuit adaptively connected with the current sensor main body; the self-recovery circuit is adaptively connected with the current sensor main body and the main feedback circuit, is used for recovering the magnetic flux state of the zero-magnetic-flux current sensor to a zero-magnetic-flux state, and at least comprises a zero-magnetic-flux state detection circuit and a scanner, and when the zero-magnetic-flux state detection circuit detects that the magnetic flux state of the current sensor main body is a non-zero-magnetic-flux state, the scanner detects that the magnetic flux state of the current sensor main body is a non-zero-magnetic-flux state. And if so, configuring a scanner to be adaptively connected with the main feedback circuit so as to recover the magnetic flux state of the current sensor main body to the zero magnetic flux state by using the scanner. According to the utility model, the zero-flux current sensor can be effectively recovered and controlled, and the working adaptability and reliability of the zero-flux current sensor are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a current sensor especially a zero magnetic flux current sensor with self -recovery ability. BACKGROUND

[0002] The magnetic modulation type or magnetic flux gate type current sensor is a closed loop feedback zero magnetic flux sensor, and the working principle is based on the magnetic saturation of the internal core alternating excitation, and has a high current measurement precision level.

[0003] In certain specific states, such as bus current exceeding the range, the feedback current cannot be fully compensated, resulting in the iron core being in the magnetic saturation state all the time, at this time, the sensing function of the iron core is invalid, and the sensor cannot work normally. After that, even if the bus current is removed, the existence of the feedback current still makes the iron core in the saturation state and cannot exit, so it can be seen that the magnetic modulation type or magnetic flux gate type current sensor cannot autonomously recover to the normal working state.

[0004] In addition, before the current sensor is powered on, the bus has current, in this case, the magnetic modulation type or magnetic flux gate type current sensor also cannot autonomously enter the normal working state. It should be noted that the current sensor is powered on after the overrange or the bus has current, which is often encountered in actual application scenarios, and improper handling can cause current sensor failure and damage. At this time, the current sensor needs to be restored to the normal working state, so it can be seen that for the current sensor, it is of great significance to realize an effective recovery mechanism, cope with complex use scenarios, and improve reliability and applicability.

[0005] In summary, for the magnetic modulation type or magnetic flux gate type current sensor, how to realize an effective and reliable sensor self-recovery circuit is a technical problem to be solved at present. SUMMARY

[0006] The utility model discloses a kind of zero magnetic flux current sensors with self-recovery ability, which can effectively restore control to zero magnetic flux current sensor, improve the adaptability and reliability of zero magnetic flux current sensor work.

[0007] According to the technical scheme provided by the utility model, a zero magnetic flux current sensor with self-recovery ability comprises:

[0008] The zero magnetic flux current sensor body includes a current sensor main body and a main feedback circuit connected to the current sensor main body.

[0009] The self-recovery circuit is connected to the current sensor main body and the main feedback circuit, and is used to restore the magnetic flux state of the zero magnetic flux current sensor to the zero magnetic flux state. It at least includes a zero magnetic flux state detection circuit and a scanner.

[0010] The zero flux state detection circuit detects that the magnetic flux state of the current sensor main body is a non-zero magnetic flux state, and then the scanner is connected to the main feedback circuit in an adaptive manner to restore the magnetic flux state of the current sensor main body to a zero magnetic flux state by using the scanner.

[0011] The main feedback circuit comprises a main feedback integration circuit and a power amplifier connected to the main feedback integration circuit in an adaptive manner, wherein,

[0012] The input end of the scanner is connected to the output end of the main feedback integration circuit, and the output end of the scanner is connected to the input end of the main feedback integration circuit through a recovery controlled switch and a self-recovery input resistor;

[0013] The control end of the recovery controlled switch is connected to the output end of the zero flux state detection circuit,

[0014] When the magnetic flux state of the current sensor main body is a non-zero magnetic flux state, the zero flux state detection circuit controls the recovery controlled switch to be in an effective state, so that the scanner is connected to the main feedback circuit;

[0015] When the magnetic flux state of the current sensor main body is a zero magnetic flux state, the zero flux state detection circuit controls the recovery controlled switch to be in a non-effective state, so that the scanner is disconnected from the main feedback circuit.

[0016] The main feedback integration circuit comprises a main feedback operational amplifier, wherein,

[0017] The non-inverting end of the main feedback operational amplifier is grounded, the inverting end of the main feedback operational amplifier is connected to one end of an integral feedback resistor, one end of an integral input resistor and a first end of a self-recovery input resistor, and the other end of the integral feedback resistor is connected to the output end of the main feedback operational amplifier through an integral feedback capacitor;

[0018] The scanner comprises at least a threshold hysteresis comparator, the input end of the threshold hysteresis comparator is connected to the output end of the main feedback operational amplifier and the input end of the power amplifier, the output end of the threshold hysteresis comparator is connected to the first end of the recovery controlled switch, and the second end of the self-recovery input resistor is connected to the second end of the recovery controlled switch.

[0019] The threshold hysteresis comparator comprises a threshold hysteresis main unit, wherein,

[0020] The threshold hysteresis main unit is an operational amplifier or a comparator, wherein, the inverting end of the threshold hysteresis main unit is grounded, the non-inverting end of the threshold hysteresis main unit is connected to the first end of a threshold hysteresis input resistor and the first end of a threshold hysteresis feedback resistor, and the second end of the threshold hysteresis input resistor is connected to the output end of the main feedback operational amplifier and the input end of the power amplifier;

[0021] The second end of the threshold hysteresis feedback resistor is connected with the output end of the threshold hysteresis main unit and the first end of the threshold hysteresis first voltage dividing resistor, the second end of the threshold hysteresis first voltage dividing resistor is connected with the first end of the threshold hysteresis second voltage dividing resistor and the first end of the recovery controlled switch, and the second end of the threshold hysteresis second voltage dividing resistor is grounded.

[0022] The recovery controlled switch is a relay, an analog switch, a MOSFET tube or a JFET tube.

[0023] The zero magnetic flux state detection circuit is adaptively connected with an excitation source in the current sensor main body, wherein the excitation source is a self-resonance type excitation source or a fixed frequency type excitation source.

[0024] When the excitation source is a self-resonance type excitation source, the self-resonance type excitation source comprises a self-resonance type oscillator for generating a square wave signal.

[0025] When the self-resonance type excitation source adopts the self-resonance type oscillator, the zero magnetic flux state detection circuit comprises a state detection first capacitor, a low-pass filter and a detector connected in sequence, and a scanner is adaptively connected with a main feedback circuit based on a detection direct current signal output by the detector.

[0026] The detector comprises a detection diode, a detection resistor and a detection capacitor, wherein,

[0027] The anode end of the detection diode is connected with the output end of the low-pass filter, the cathode end of the detection diode is connected with one end of the detection resistor and one end of the detection capacitor, and the cathode end of the detection diode and the detection resistor and the detection capacitor are connected with each other to form an output end of the detector.

[0028] The other end of the detection resistor and the other end of the detection capacitor are both grounded.

[0029] When the excitation source is a fixed frequency type excitation source, the zero magnetic flux state detection circuit comprises a state detection second capacitor, wherein,

[0030] The first end of the state detection second capacitor is connected with the output end of the fixed frequency type excitation source, the second end of the state detection second capacitor is connected with the first end of the coil inductance and the input end of the amplitude comparator, and the second end of the coil inductance is grounded through a current detection resistor.

[0031] A scanner is adaptively connected with a main feedback circuit based on an amplitude comparison signal output by the amplitude comparator.

[0032] The amplitude comparator comprises an amplitude comparison main unit, wherein,

[0033] The amplitude comparison main unit adopts an operational amplifier or a comparator, the non-inverting terminal of the amplitude comparison main unit is connected with a comparison threshold value, and the inverting terminal of the amplitude comparison main unit is connected with a second end of a state detection second capacitor and a first end of a coil inductor through an amplitude comparison input resistor;

[0034] The output end of the amplitude comparison main unit is connected with the anode end of an amplitude comparison diode through an amplitude comparison intermediate resistor, the cathode end of the amplitude comparison diode is connected with one end of an amplitude comparison capacitor, and the cathode end of the amplitude comparison diode and the amplitude comparison capacitor form an output end of the amplitude comparison main unit;

[0035] The other end of the amplitude comparison capacitor is grounded.

[0036] The advantages of the utility model are as follows: the self-recovery circuit is connected with the main feedback circuit of the zero-flux current sensor, the zero-flux state of the current sensor main body is detected through the magnetic flux state detection circuit, then the recovery controlled switch can be controlled to be closed, when the recovery controlled switch is closed, the scanner is connected with the main feedback circuit, the signal generated by the scanner is injected into the main feedback circuit, so that the recovery direction scanning and locking are realized through the cooperation of the scanner and the main feedback circuit, and finally the current sensor can be recovered from the non-zero-flux state to the zero-flux state, the recovery control of the zero-flux current sensor is effectively realized, and the adaptability and reliability of the zero-flux current sensor are improved. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is an embodiment circuit principle diagram of the utility model zero-flux current sensor.

[0038] Figure 2 It is an embodiment circuit block diagram of the utility model zero-flux state detection circuit.

[0039] Figure 3 It is another embodiment circuit block diagram of the utility model zero-flux state detection circuit.

[0040] Figure 4 It is an embodiment circuit principle diagram of the utility model scanner.

[0041] Figure 5 It is an embodiment circuit principle diagram of the utility model low-pass filter.

[0042] Figure 6 It is an embodiment circuit principle diagram of the utility model detector.

[0043] Figure 7 It is an embodiment circuit principle diagram of the utility model amplitude comparator.

[0044] Figure 8The utility model discloses a kind of embodiment circuit principle diagram of controlled switch recovery using normal type.

[0045] Mark explanation: 1-main feedback circuit, 2-self recovery circuit, 3-zero flux state detection circuit, 4-self resonant oscillator, 5-fixed frequency type excitation source, 6-main feedback operational amplifier, 7-integral input resistance, 8-integral feedback resistance, 9-integral feedback capacitor, 10-power amplifier, 11-self recovery input resistance, 12-recovery controlled switch, 13-scanner, 14-zero flux state detection circuit output end, 15-threshold hysteresis input resistance, 16-state detection first capacitor, 17-low pass filter, 18-detector, 19-threshold hysteresis feedback resistance, 20-state detection second capacitor, 21-coil inductance, 22-current detection resistance, 23-coil inductance core, 24-amplitude comparator, 25-threshold hysteresis main unit, 26-threshold hysteresis first voltage dividing resistance, 27-threshold hysteresis second voltage dividing resistance, 28-low pass filter resistance, 29-low pass filter capacitor, 30-detection diode, 31-detection capacitor, 32-detection resistance, 33-amplitude comparison input resistance, 34-amplitude comparison capacitor, 35-amplitude comparison main unit, 36-amplitude comparison intermediate resistance, 37-amplitude comparison diode. DETAILED DESCRIPTION

[0046] The utility model will be further described below in combination with specific drawing and embodiment.

[0047] In order to effectively control zero flux current sensor recovery, improve the adaptability and reliability of zero flux current sensor work, the utility model provides a kind of zero flux current sensor with self-recovery ability, specifically, the zero flux current sensor includes:

[0048] Zero flux current sensor body, including current sensor main body and the main feedback circuit 1 of the current sensor main body adaptive connection;

[0049] Self recovery circuit 2, with current sensor main body and main feedback circuit 1 adaptive connection, for the magnetic flux state of zero flux current sensor is recovered to zero flux state, at least including zero flux state detection circuit 3 and scanner 13, wherein,

[0050] When the magnetic flux state of current sensor main body is non-zero flux state, then configure scanner 13 and main feedback circuit 1 adaptive connection, to utilize scanner 13 and restore the magnetic flux state of current sensor main body to zero flux state.

[0051] It should be noted that the zero flux current sensor can be a magnetic modulation type or a flux gate type current sensor, and the zero flux current sensor should work in a zero flux state, and the type and specific working principle of the zero flux current sensor are consistent with the prior art. For the zero flux current sensor, the zero flux current sensor body is the part that realizes the main function of the zero flux current sensor. Generally, the zero flux current sensor body should include a current sensor body and a main feedback circuit 1. The current sensor body is the part that realizes the main function of the zero flux current sensor, and the form of the current sensor body should be related to the type of the zero flux current sensor, Figure 1 Only part of the main feedback circuit 1 is shown in the figure. Generally, the main feedback circuit 1 restores the flux state of the current sensor body through feedback. The role of the main feedback circuit 1 and the cooperation mode between the main feedback circuit 1 and the current sensor body can be consistent with the prior art, and details are not repeated here.

[0052] In order to improve the recovery ability of the zero flux current sensor, in an embodiment of the utility model, the self-recovery circuit 2 is connected with the main feedback circuit 1, like Figure 1 As described above, the self-recovery circuit 2 should be connected with the current sensor body and the main feedback circuit 1 to restore the flux state of the zero flux current sensor to the zero flux state. Figure 1 An embodiment of the self-recovery circuit 2 is shown in the figure. As can be seen from the figure, the self-recovery circuit 2 should at least include a zero flux state detection circuit 3 and a scanner 13. The zero flux state detection circuit 3 mainly detects the flux state of the zero flux current sensor, that is, mainly detects whether the flux state of the zero flux current sensor is the zero flux state.

[0053] When the zero flux current sensor is recovered, it specifically means that the zero flux current sensor is restored from a non-zero flux state to a zero flux state. Therefore, when the zero flux state detection circuit 3 determines that the flux state of the zero flux current sensor is a non-zero flux state, the scanner 13 should be connected and cooperated with the main feedback circuit 1 to ensure that the flux state of the current sensor body is restored to the zero flux state. When the flux state of the zero flux current sensor is restored to the zero flux state, the zero flux state detection circuit 3 can control the scanner 13 to disconnect the electrical connection between the scanner 13 and the main feedback circuit 1, that is, it will not affect the normal work of the zero flux current sensor. At this time, only the main feedback circuit 1 can be used to keep the flux state of the zero flux current sensor as the zero flux state, that is, it is compatible with the existing zero flux current sensor, and the adaptability and reliability of the zero flux current sensor can be improved.

[0054] In an embodiment of the utility model, the main feedback circuit 1 includes a main feedback integration circuit and a power amplifier 10 connected with the main feedback integration circuit, wherein,

[0055] The input end of the scanner 13 is connected with the output end of the main feedback integral circuit, and the output end of the scanner 13 is connected with the input end of the main feedback integral circuit through the recovery controlled switch 12 and the self-recovery input resistor 11;

[0056] The control end of the recovery controlled switch 12 is connected with the output end of the zero magnetic state detection circuit 3,

[0057] When the magnetic state of the current sensor body is the non-zero magnetic state, the zero magnetic state detection circuit 3 controls the recovery controlled switch 12 to be in the effective state, so that the scanner 13 is connected with the main feedback circuit;

[0058] When the magnetic state of the current sensor body is the zero magnetic state, the zero magnetic state detection circuit 3 controls the recovery controlled switch 12 to be in the ineffective state, so that the scanner 13 is disconnected with the main feedback circuit.

[0059] Figure 1 In the main feedback circuit 1 shown in the figure, the main feedback circuit 1 can include the main feedback integral circuit and the power amplifier 10, the input end of the main feedback integral circuit is connected with the current sensor body, of course, the output end of the power amplifier 10 should also be connected with the current sensor body in a matched manner to form a negative feedback connection. The power amplifier 10 can adopt a commonly used form, the main feedback integral circuit is used to output an integral signal which is monotonously increased or monotonously decreased, and the integral signal can be amplified by the power amplifier 10, so as to adjust the magnetic state of the current sensor body.

[0060] In order to realize the matched connection between the scanner 13 and the main feedback circuit 1, Figure 1 An embodiment using the recovery controlled switch 12 matched with the scanner 13 and the main feedback circuit 1 is shown in the figure, the recovery controlled switch 12 can be a relay, an analog switch, a MOSFET tube or a JFET tube. The switch state of the recovery controlled switch 12 is controlled by the zero magnetic state detection circuit 3, for example, when the zero magnetic state detection circuit 3 determines that the current sensor body is in the non-zero magnetic state, the recovery controlled switch 12 is controlled to be in the effective state, at this time, the scanner 13 is electrically connected with the main feedback circuit 1, otherwise, the recovery controlled switch 12 is controlled to be in the ineffective state, and the scanner 13 is disconnected with the main feedback circuit 1.

[0061] It can be understood that when the recovery controlled switch 12 is in the effective state, the scanner 13 can be matched and electrically connected with the main feedback circuit 1 through the recovery controlled switch 12; when the recovery controlled switch 12 is in the ineffective state, the scanner 13 cannot be matched and electrically connected with the main feedback circuit 1, and the specific matched and electrically connected state will be described below.

[0062] It should be noted that the recovery controlled switch 12 can be a normally-off or normally-on type, when the recovery controlled switch 12 is of the normally-off type, the recovery controlled switch 12 is located between the output of the scanner 13 and the main feedback circuit 1, the current sensor body is in the zero magnetic flux state, the recovery controlled switch 12 keeps off state, at this time, the recovery controlled switch 12 is in the non-effective state, the output signal of the scanner 13 is interrupted, and the output signal of the scanner 13 cannot be adaptively connected with the main feedback circuit 1. When the current sensor body is in the non-zero magnetic flux state, the zero magnetic flux state detection circuit 3 controls the normally-off type recovery controlled switch 12 to be closed, at this time, the recovery controlled switch 12 is in the effective state, and the output end of the scanner 13 can be adaptively connected with the main feedback circuit 1 through the recovery controlled switch 12.

[0063] In specific implementation, the normally-off type recovery controlled switch 12 can be formed by using the normally-open contact of a relay, a normally-open analog switch, a MOSFET tube or a JFET tube, and the normally-off state of the recovery controlled switch 12 can be consistent with the prior art, which will not be described here.

[0064] When the recovery controlled switch 12 is of the normally-on type, one end of the recovery controlled switch 12 is adaptively connected with the output end of the scanner 13 and the main feedback circuit 1, and the other end of the recovery controlled switch 12 is grounded, as shown in the figure, when the current sensor body is in the zero magnetic flux state, the recovery controlled switch 12 keeps closed state, at this time, the recovery controlled switch 12 is in the non-effective state, the output end of the scanner 13 is grounded, and the output state of the scanner 13 is not effective. When the current sensor body is in the non-zero magnetic flux state, the zero magnetic flux state detection circuit 3 controls the recovery controlled switch 12 to be opened, the recovery controlled switch 12 is in the effective state, and the output signal of the scanner 13 is injected into the positive feedback circuit 1. Figure 8

[0065] In specific implementation, the type of the recovery controlled switch 12 can be selected according to actual needs, so as to meet the adaptive electrical connection requirement between the controlled scanner 13 and the main feedback circuit 1.

[0066] In one embodiment of the utility model, the main feedback integration circuit includes a main feedback operational amplifier 6, wherein,

[0067] The noninverting terminal of the main feedback operational amplifier 6 is grounded, the inverting terminal of the main feedback operational amplifier 6 is connected with one end of an integration feedback resistor 8, one end of an integration input resistor 7 and the first end of a self-recovery input resistor 11, and the other end of the integration feedback resistor 8 is connected with the output end of the main feedback operational amplifier 6 through an integration feedback capacitor 9;

[0068] ​The scanner 13 at least includes a threshold hysteresis comparator, the input end of the threshold hysteresis comparator is connected with the output end of the main feedback operational amplifier 6 and the input end of the power amplifier 10, the output end of the threshold hysteresis comparator is connected with the first end of the recovery controlled switch 12, and the second end of the self-recovery input resistor 11 is connected with the second end of the recovery controlled switch 12.

[0069] Specifically, the other end of the integral input resistor 7 should be connected with the current sensor main body, and the form that the integral input resistor 7 cooperates with the current sensor main body can be consistent with the prior art. In operation, the main feedback operational amplifier 6 outputs a voltage, and normally, the absolute value of the voltage output by the main feedback operational amplifier 6 should be a voltage value not higher than the threshold value of the scanner 13; when the voltage output by the main feedback operational amplifier 6 exceeds the threshold value of the scanner 13, the scanner 13 can judge that the current sensor main body is in a non-zero magnetic flux state, at this time, the main feedback circuit 1 is in a failure state, that is, the zero magnetic flux current sensor cannot be restored to the zero magnetic flux state.

[0070] In specific implementation, the scanner 13 can adopt a threshold hysteresis comparator, the threshold hysteresis comparator can compare the voltage output by the main feedback operational amplifier 6, when the recovery controlled switch 12 is in a closed state, the output of the scanner 13 is injected into the inverting end of the main feedback operational amplifier 6 through the recovery controlled switch 12 and the self-recovery input resistor 11, so as to adjust the input of the main feedback circuit 1, thereby ensuring that the zero magnetic flux current sensor is restored to the zero magnetic flux state from the non-zero magnetic flux state.

[0071] In an embodiment of the utility model, the threshold hysteresis comparator includes a threshold hysteresis main unit 25, wherein,

[0072] The threshold hysteresis main unit 25 is an operational amplifier or a comparator, wherein the inverting end of the threshold hysteresis main unit 25 is grounded, the non-inverting end of the threshold hysteresis main unit 25 is connected with the first end of the threshold hysteresis input resistor 15 and the first end of the threshold hysteresis feedback resistor 19, and the second end of the threshold hysteresis input resistor 15 is connected with the output end of the main feedback operational amplifier 6 and the input end of the power amplifier 10;

[0073] The second end of the threshold hysteresis feedback resistor 19 is connected with the output end of the threshold hysteresis main unit 25 and the first end of the threshold hysteresis first voltage dividing resistor 26, the second end of the threshold hysteresis first voltage dividing resistor 26 is connected with the first end of the threshold hysteresis second voltage dividing resistor 27 and the first end of the recovery controlled switch 12, and the second end of the threshold hysteresis second voltage dividing resistor 27 is grounded.

[0074] Figure 4An embodiment of the threshold hysteresis comparator is shown in FIG. 1. The threshold hysteresis main unit 25 can be an operational amplifier or a comparator. The inverting terminal and the non-inverting terminal of the threshold hysteresis main unit 25 are the inverting terminal and the non-inverting terminal of the operational amplifier or the comparator. As shown in FIG. 1, the threshold hysteresis main unit 25 is in a positive feedback state. The threshold value of the threshold hysteresis main unit 25 is determined by the ratio of the threshold hysteresis input resistor 15 and the threshold hysteresis feedback resistor 19.

[0075] Specifically, the node where the threshold hysteresis first voltage divider resistor 26 and the threshold hysteresis second voltage divider resistor 27 are connected forms the output terminal of the scanner 13. When the output terminal of the scanner 13 is connected to the inverting terminal of the main feedback operational amplifier 6 through the self-recovery input resistor 11, the adaptive electrical connection between the scanner 13 and the main feedback circuit 1 is achieved.

[0076] Generally, the output voltage of the threshold hysteresis main unit 25 is close to the supply voltage of the threshold hysteresis main unit 25. The resistance value of the threshold hysteresis feedback resistor 19 is greater than the resistance value of the threshold hysteresis input resistor 15. The threshold value of the threshold hysteresis main unit 25 is approximately equal to the supply voltage multiplied by the ratio of the resistance 15 and the resistance 19, which has two values, positive and negative. The output value of the threshold hysteresis main unit 25 is close to the supply voltage, and the signal is strong. The signal amplitude can be reduced by the threshold hysteresis first voltage divider resistor 26 and the threshold hysteresis second voltage divider resistor 27. In the normal working state, within the range of the current sensor, the output of the main feedback operational amplifier 6 is always lower than the threshold value of the threshold hysteresis main unit 25.

[0077] In the non-zero magnetic flux state, the output of the threshold hysteresis main unit 25 is Figure 4 As shown in FIG. 1, when the output voltage of the main feedback operational amplifier 6 exceeds the threshold value of the threshold hysteresis main unit 25, the scanner 13 will be reversed, and the scanning direction of the scanner 13 will be turned to the other direction. Specifically, when the threshold hysteresis main unit 25 outputs a positive value, the output is loaded to the inverting terminal of the main feedback operational amplifier 6 through the threshold hysteresis first voltage divider resistor 26 and the threshold hysteresis second voltage divider resistor 27, the recovery controlled switch 12 and the self-recovery input resistor 11. Through the integral feedback capacitor 9, the main feedback operational amplifier 6 outputs a waveform that continuously decreases. When the negative threshold value of the threshold hysteresis main unit 25 is reached, the output of the threshold hysteresis main unit 25 is reversed. At this time, the threshold hysteresis main unit 25 outputs a negative value. Thereafter, the output of the threshold hysteresis main unit 25 is loaded to the inverting terminal of the main feedback operational amplifier 6, and the main feedback operational amplifier 6 outputs a waveform that continuously increases until the positive threshold value is reached, and the reversal occurs again.

[0078] As can be seen from the above description, the scanner 13 can realize scanning search in two directions of positive and negative.

[0079] In an embodiment of the utility model, the zero magnetic flux state detection circuit 3 is connected with the excitation source in the current sensor main body, wherein the excitation source is a self-resonance type excitation source or a fixed frequency type excitation source 5.

[0080] Generally, the excitation source for generating excitation signal exists in the current sensor main body, generally, the excitation source is a self-resonance type excitation source or a fixed frequency type excitation source 5, and the type of excitation source can be selected as required. Generally, when the type of excitation source is different, the form of zero magnetic flux state detection circuit 3 is generally different, and the form of zero magnetic flux state detection circuit 3 will be specifically described below in combination with the different excitation sources.

[0081] In an embodiment of the utility model, when the excitation source is a self-resonance type excitation source, the self-resonance type excitation source includes a self-resonance type oscillator 4 for generating a square wave signal.

[0082] When the self-resonance type excitation source adopts the self-resonance type oscillator 4, the zero magnetic flux state detection circuit 3 includes a state detection first capacitor 16, a low-pass filter 17 and a detector 18 connected in sequence, and the adaptive connection state of the scanner 13 and the main feedback circuit 1 is configured based on the detection direct current signal output by the detector 18.

[0083] Figure 2 An embodiment of the cooperation of the zero magnetic flux state detection circuit 3 and the self-resonance type oscillator 4 when the self-resonance type excitation source adopts the self-resonance type oscillator 4 is shown in Fig. 4. As can be seen from the figure, at this time, the zero magnetic flux state detection circuit 3 should include a state detection first capacitor 16, a low-pass filter 17 and a detector 18. Generally, the self-resonance type oscillator 4 generates a square wave signal, and the state detection first capacitor 16 serves as a direct current blocking capacitor.

[0084] When the main feedback circuit 1 is in a feedback balance state, that is, the core of the self-resonance type oscillator 4 is in a zero magnetic flux state, the oscillation frequency of the square wave generated by the self-resonance type oscillator 4 is the lowest. When the core of the self-resonance type oscillator 4 is in a non-zero magnetic flux state, the oscillation frequency of the self-resonance type oscillator 4 will increase. The more the zero magnetic flux state deviates, the higher the oscillation frequency, and the square wave form will also be distorted. When reaching a certain degree, the oscillator stops oscillating.

[0085] In implementation, the output square wave signal of the self-resonant oscillator 4 is first passed through the state detection first capacitor 16, which can isolate the direct current signal output when the self-resonant oscillator 4 stops. The stop of the self-resonant oscillator 4 indicates that the current sensor main body is in a non-zero magnetic flux state (abnormal state), and if the direct current signal is not isolated by the state detection first capacitor 16, it may cause the rear stage to be wrongly judged. The signal after being isolated by the state detection first capacitor 16 is then input into the low-pass filter 17 to shape the square wave signal into a signal similar to a triangular wave, and the higher the input frequency, the lower the amplitude of the output triangular wave; the signal after being filtered by the low-pass filter 17 is input into the detector 18 to change the triangular wave into a direct current signal, that is, the detector 18 outputs a direct current signal; when the amplitude of the direct current signal output by the detector 18 is greater than the opening voltage of the recovery controlled switch 12, the recovery controlled switch 12 is in an effective state, otherwise, the recovery controlled switch 12 is in a non-effective state.

[0086] The low-pass filter 17 can adopt a common low-pass filtering form, Figure 5 Fig. 2 shows an embodiment of the low-pass filter 17, in which the low-pass filter 17 can include a low-pass filter resistor 28 and a low-pass filter capacitor 29, wherein one end of the low-pass filter resistor 28 is connected with the state detection first capacitor 16, the other end of the low-pass filter resistor 28 is connected with the input end of the detector 18 and one end of the low-pass filter capacitor 29, and the other end of the low-pass filter capacitor 29 is grounded. Of course, the low-pass filter 17 can also adopt other forms, which can be selected according to needs, and details are not described here.

[0087] In an embodiment of the utility model, the detector 18 includes a detection diode 30, a detection resistor 32 and a detection capacitor 31, wherein,

[0088] The anode end of the detection diode 30 is connected with the output end of the low-pass filter 17, the cathode end of the detection diode 30 is connected with one end of the detection resistor 32 and one end of the detection capacitor 31, and the cathode end of the detection diode 30 is connected with the detection resistor 32 and the detection capacitor 31 to form the output end of the detector 18;

[0089] The other end of the detection resistor 32 and the other end of the detection capacitor 31 are both grounded.

[0090] Figure 6 Fig. 2 shows an embodiment of the low-pass filter 18, and from the above description, when the detector 18 adopts Figure 6 the circuit form, the triangular wave output by the low-pass filter 17 can be converted into a direct current signal, of course, the form adopted by the detector 18 should be related to the type adopted by the recovery controlled switch 12, and details are subject to the switch state of the recovery controlled switch 12.

[0091] In one embodiment of the utility model, when the excitation source is fixed frequency excitation source 5, the zero flux state detection circuit 3 includes state detection second capacitor 20, wherein,

[0092] The first end of state detection second capacitor 20 is connected with the output end of fixed frequency excitation source 5, the second end of state detection second capacitor 20 is connected with the first end of coil inductance 21 and the input end of amplitude comparator 24, and the second end of coil inductance 21 is grounded through current detection resistor 22;

[0093] The amplitude comparison signal output by amplitude comparator 24 is configured to be adaptively connected with the state of scanner 13 and main feedback circuit 1.

[0094] Specifically, when the excitation source adopts fixed frequency excitation source 5, the frequency of the signal generated by fixed frequency excitation source 5 is fixed, and the frequency detection mode cannot be adopted, at this time, the amplitude detection mode can be adopted. Amplitude comparator 24 compares the amplitude to determine the zero flux state of the current sensor main body, Figure 3 A circuit principle diagram of zero flux state detection circuit 3 at this time is shown in Fig. 3. It should be noted that in the zero flux state, the equivalent inductance value of coil inductance 21 is the largest, and the voltage drop thereon is also the largest. The more the zero flux state deviates, the deeper the saturation degree of the iron core 23 in the coil inductance 21, and the equivalent inductance value decreases, and the voltage drop gradually decreases. Therefore, the amplitude of the voltage drop can be compared and judged by using the amplitude comparator 24 to determine whether the current sensor main body is in the zero flux state. It can be understood that the amplitude comparison signal output by the amplitude comparator 24 is the output value of the zero flux state detection circuit 3. When the amplitude of the amplitude comparison signal is greater than the opening voltage of the recovery controlled switch 12, the recovery controlled switch 12 is in the effective state, otherwise, the recovery controlled switch 12 is in the non-effective state.

[0095] In one embodiment of the utility model, the amplitude comparator 24 includes amplitude comparison main unit 35, wherein,

[0096] The amplitude comparison main unit 35 adopts an operational amplifier or a comparator, the non-inverting terminal of the amplitude comparison main unit 35 is connected with the second end of state detection second capacitor 20 and the first end of coil inductance 21 through amplitude comparison input resistor 33, and the inverting terminal of the amplitude comparison main unit 35 is connected with the second end of state detection second capacitor 20 and the first end of coil inductance 21 through amplitude comparison input resistor 33.

[0097] The output end of amplitude comparison main unit 35 is connected with the anode end of amplitude comparison diode 37 through amplitude comparison intermediate resistor 36, the cathode end of amplitude comparison diode 37 is connected with one end of amplitude comparison capacitor 34, and the cathode end of amplitude comparison diode 37 and amplitude comparison capacitor 34 form the output end of the amplitude comparator after being connected.

[0098] The other end of the amplitude comparison capacitor 34 is grounded.

[0099] Figure 7 An embodiment of the amplitude comparator 24 is shown in FIG. 2. The amplitude comparison main unit 35 can be an operational amplifier or a comparator, and thus the non-inverting terminal and the inverting terminal of the amplitude comparison main unit 35 are the corresponding non-inverting terminal and inverting terminal of the operational amplifier or the comparator. The comparison threshold value can be selected according to requirements, and the output terminal of the amplitude comparator can be the output terminal 14 of the zero magnetic flux state detection circuit. That is, through the comparison state of the amplitude comparator 24, the switching state of the recovery controlled switch 12 can be controlled. In a specific implementation, the comparison threshold value of the non-inverting terminal of the amplitude comparison main unit 35 can be obtained by dividing the power supply voltage or by dividing a reference voltage. The size of the comparison threshold value can be selected according to actual requirements, and the comparison threshold value should be able to meet the amplitude comparison requirements.

[0100] As can be seen from the above description, the self-recovery circuit 2 is connected to the main feedback circuit 1 of the zero magnetic flux current sensor. The zero magnetic flux state of the current sensor main body is detected by the magnetic flux state detection circuit 3. Then, the recovery controlled switch 12 can be controlled to be closed. After the recovery controlled switch 12 is closed, the scanner 13 is connected to the main feedback circuit 1. Then, the signal generated by the scanner 13 is injected into the main feedback circuit 1. The main feedback circuit 1 can be used to accelerate the recovery of the current sensor main body, that is, to accelerate the recovery of the current sensor from a non-zero magnetic flux state to a zero magnetic flux state. The zero magnetic flux current sensor recovery control can be effectively controlled, and the adaptability and reliability of the zero magnetic flux current sensor in operation can be improved.

Claims

1. A zero-flux current sensor with self-recovery capability, characterized in that, The zero-flux current sensor comprises: a zero-flux current sensor body comprising a current sensor main body and a main feedback circuit connected to the current sensor main body; a self-recovery circuit connected to the current sensor main body and the main feedback circuit, and configured to restore the magnetic flux state of the zero-flux current sensor to a zero-flux state, and comprising at least a zero-flux state detection circuit and a scanner, when the zero-flux state detection circuit detects that the magnetic flux state of the current sensor main body is a non-zero-flux state, the scanner is connected to the main feedback circuit to restore the magnetic flux state of the current sensor main body to a zero-flux state by using the scanner.

2. The zero flux current sensor with self-recovery capability according to claim 1, characterized in that: The main feedback circuit comprises a main feedback integration circuit and a power amplifier connected to the main feedback integration circuit, wherein the input end of the scanner is connected to the output end of the main feedback integration circuit, and the output end of the scanner is connected to the input end of the main feedback integration circuit through a recovery controlled switch and a self-recovery input resistor; the control end of the recovery controlled switch is connected to the output end of the zero-flux state detection circuit, when the magnetic flux state of the current sensor main body is a non-zero-flux state, the zero-flux state detection circuit controls the recovery controlled switch to be in an effective state, so that the scanner is connected to the main feedback circuit; when the magnetic flux state of the current sensor main body is a zero-flux state, the zero-flux state detection circuit controls the recovery controlled switch to be in a non-effective state, so that the scanner is disconnected from the main feedback circuit.

3. The zero flux current sensor with self-recovery capability according to claim 2, characterized in that: The main feedback integration circuit comprises a main feedback operational amplifier, wherein the non-inverting terminal of the main feedback operational amplifier is connected to ground, and the inverting terminal of the main feedback operational amplifier is connected to one end of an integration feedback resistor, one end of an integration input resistor, and a first end of a self-recovery input resistor, and the other end of the integration feedback resistor is connected to the output end of the main feedback operational amplifier through an integration feedback capacitor; The scanner comprises at least a threshold hysteresis comparator, wherein the input end of the threshold hysteresis comparator is connected to the output end of the main feedback operational amplifier and the input end of the power amplifier, the output end of the threshold hysteresis comparator is connected to the first end of the recovery controlled switch, and the second end of the self-recovery input resistor is connected to the second end of the recovery controlled switch.

4. The zero flux current sensor with self-recovery capability according to claim 3, characterized in that: The threshold hysteresis comparator comprises a threshold hysteresis main unit, wherein the threshold hysteresis main unit is an operational amplifier or a comparator, wherein the inverting terminal of the threshold hysteresis main unit is connected to ground, the non-inverting terminal of the threshold hysteresis main unit is connected to the first end of a threshold hysteresis input resistor and the first end of a threshold hysteresis feedback resistor, and the second end of the threshold hysteresis input resistor is connected to the output end of the main feedback operational amplifier and the input end of the power amplifier; the second end of the threshold hysteresis feedback resistor is connected to the output end of the threshold hysteresis main unit and the first end of a threshold hysteresis first voltage dividing resistor, the second end of the threshold hysteresis first voltage dividing resistor is connected to the first end of a threshold hysteresis second voltage dividing resistor and the first end of the recovery controlled switch, and the second end of the threshold hysteresis second voltage dividing resistor is connected to ground.

5. The zero flux current sensor with self-recovery capability according to claim 2, characterized in that: The recovery controlled switch is a relay, an analog switch, a MOSFET tube, or a JFET tube.

6. The zero flux current sensor with self-recovery capability according to any one of claims 1 to 5, characterized in that: The zero flux state detection circuit is connected with an excitation source in the current sensor main body, wherein the excitation source is a self-resonance type excitation source or a fixed frequency type excitation source.

7. The zero flux current sensor with self-recovery capability according to claim 6, characterized in that: When the excitation source is a self-resonance type excitation source, the self-resonance type excitation source comprises a self-resonance type oscillator for generating a square wave signal. When the self-resonance type excitation source adopts the self-resonance type oscillator, the zero flux state detection circuit comprises a state detection first capacitor, a low pass filter and a detector connected in sequence, and a scanner and a main feedback circuit are connected based on a detection DC signal output by the detector.

8. The zero flux current sensor with self-recovery capability according to claim 7, characterized in that: The detector comprises a detection diode, a detection resistor and a detection capacitor, wherein, the anode end of the detection diode is connected with the output end of the low pass filter, the cathode end of the detection diode is connected with one end of the detection resistor and one end of the detection capacitor, and the cathode end of the detection diode is connected with the detection resistor and the detection capacitor to form the output end of the detector; the other end of the detection resistor and the other end of the detection capacitor are grounded.

9. The zero flux current sensor with self-recovery capability according to claim 6, characterized in that: When the excitation source is a fixed frequency type excitation source, the zero flux state detection circuit comprises a state detection second capacitor, wherein, the first end of the state detection second capacitor is connected with the output end of the fixed frequency type excitation source, the second end of the state detection second capacitor is connected with the first end of the coil inductance and the input end of the amplitude comparator, and the second end of the coil inductance is grounded through a current detection resistor; a scanner and a main feedback circuit are connected based on an amplitude comparison signal output by the amplitude comparator.

10. The zero flux current sensor with self-recovery capability according to claim 9, characterized in that: The amplitude comparator comprises an amplitude comparison main unit, wherein, the amplitude comparison main unit adopts an operational amplifier or a comparator, the non-inverting input end of the amplitude comparison main unit is connected with a comparison threshold value, and the inverting input end of the amplitude comparison main unit is connected with the second end of the state detection second capacitor and the first end of the coil inductance through an amplitude comparison input resistor; the output end of the amplitude comparison main unit is connected with the anode end of an amplitude comparison diode through an amplitude comparison intermediate resistor, the cathode end of the amplitude comparison diode is connected with one end of an amplitude comparison capacitor, and the cathode end of the amplitude comparison diode is connected with the amplitude comparison capacitor to form the output end of the amplitude comparator; the other end of the amplitude comparison capacitor is grounded.

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