Zero-flux current sensor and current measurement system

Abstract

The invention relates to a zero-flux current sensor and a current measurement system, and relates to the technical field of electrical variable measurement. The zero-flux current sensor comprises a magnetic core, a primary winding and a secondary winding, the primary winding and the secondary winding are respectively wound on the magnetic core, and the primary winding is used for sensing to-be-detected current of a to-be-detected wire; the compensation circuit is respectively connected with the primary winding and the secondary winding and is used for generating compensation current according to the current to be measured, so that the secondary winding generates compensation magnetic flux according to the compensation current to counteract bias magnetic flux generated by the primary winding according to the current to be measured; the signal processing circuit comprises a conditioning module and a signal processing module, the conditioning module is connected with the secondary winding and used for generating a clamping signal according to the compensation current, the clamping signal meets the signal processing condition of the signal processing module, and the signal processing module is connected with the conditioning module and used for processing the signal. The signal processing module is used for determining the current to be measured according to the clamping signal. According to the invention, the current measurement precision can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of measuring electric variables, and in particular to a zero-flux current sensor and a current measurement system. Background Art

[0002] Zero flux current sensors can be used to detect leakage and are widely used in AC and DC monitoring, DC relays, leakage circuit breakers and other protection products.

[0003] A zero-flux current sensor is a sensor used to detect AC or DC current. Its working principle is based on Faraday's law of electromagnetic induction, and it achieves high-precision current measurement by keeping the magnetic field passing through it at zero. However, existing zero-flux current sensors may not be able to capture the required signal in a timely or accurate manner, resulting in measurement errors. Summary of the invention

[0004] Based on this, it is necessary to provide a zero-flux current sensor and a current measurement system that can improve measurement accuracy.

[0005] In a first aspect, an embodiment of the present application provides a zero-flux current sensor, including:

[0006] A magnetic core, a primary winding and a secondary winding, wherein the primary winding and the secondary winding are respectively wound on the magnetic core, and the primary winding is used to sense the current to be measured of the conductor to be measured;

[0007] a compensation circuit, connected to the primary winding and the secondary winding respectively, for generating a compensation current according to the current to be measured, so that the secondary winding generates a compensation flux according to the compensation current to offset the bias flux generated by the primary winding according to the current to be measured;

[0008] The signal processing circuit includes a conditioning module and a signal processing module, wherein the conditioning module is connected to the secondary winding, the conditioning module is used to generate a clamping signal according to the compensation current, the clamping signal meets the signal processing condition of the signal processing module, the signal processing module is connected to the conditioning module, and the signal processing module is used to determine the current to be measured according to the clamping signal.

[0009] In one embodiment, the conditioning module includes a first operational amplifier, a first capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor and a sixth resistor, wherein the positive input terminal of the first operational amplifier is respectively connected to the first end of the first resistor, the first end of the second resistor and the first end of the third resistor, the negative input terminal of the first operational amplifier receives a reference signal via the fourth resistor, and the negative input terminal of the first operational amplifier is respectively connected to the output terminal of the first operational amplifier and the signal processing module via the fifth resistor, the second end of the first resistor is respectively connected to the first end of the sixth resistor and the first end of the first capacitor, the second end of the second resistor receives a first power supply signal, the second end of the third resistor and the second end of the first capacitor are respectively grounded, and the second end of the sixth resistor is connected to the secondary winding.

[0010] In one of the embodiments, the signal processing module includes a filtering unit and a signal processing unit, wherein the filtering unit is connected to the conditioning module, the filtering unit is used to filter the clamping signal, and the signal processing unit is used to determine the current to be measured based on the filtered clamping signal.

[0011] In one embodiment, the filtering unit includes a first inductor, a second inductor and a second capacitor, wherein the first end of the first inductor is connected to the conditioning module, the second end of the first inductor is respectively connected to the first end of the second inductor and the second end of the second capacitor, the second end of the second inductor is connected to the signal processing unit, and the second end of the second capacitor is respectively connected to the conditioning module and the signal processing unit.

[0012] In one embodiment, the compensation circuit comprises:

[0013] an oscillation module, connected to the primary winding, and configured to self-oscillate according to the current to be measured and generate an alternating current signal;

[0014] A sampling module, connected to the primary winding, for sampling the AC signal and outputting a first sampling signal;

[0015] A phase processing module, connected to the sampling module, configured to perform inversion processing on the first sampling signal and generate a second sampling signal;

[0016] A demodulation feedback module is connected to the sampling module, the phase processing module and the secondary winding respectively, and is used to generate the compensation current according to the first sampling signal and the second sampling signal.

[0017] In one embodiment, the demodulation feedback module includes:

[0018] a peak demodulation unit, connected to the sampling module and the phase processing module respectively, and configured to generate a first peak signal according to the first sampling signal, and generate a second peak signal according to the second sampling signal;

[0019] a difference unit, connected to the peak demodulation unit, and configured to generate a peak difference signal according to the first peak signal and the second peak signal;

[0020] A feedback unit is connected to the differential unit and the secondary winding respectively, and is used to generate the compensation current according to the peak difference signal.

[0021] In one of the embodiments, the peak demodulation unit includes a first peak demodulation subunit and a second peak demodulation subunit, the first peak demodulation subunit is connected to the sampling module, and the second peak demodulation subunit is connected to the phase processing module;

[0022] The target peak demodulation subunit includes at least one of the first peak demodulation subunit and the second peak demodulation subunit, and the target peak demodulation subunit includes a second operational amplifier, a third operational amplifier, a first diode, a second diode, a second capacitor, a third capacitor, a seventh resistor and an eighth resistor, wherein the positive input terminal of the second operational amplifier receives a target sampling signal, and the target sampling signal includes at least one of the first sampling signal and the second sampling signal, the negative input terminal of the second operational amplifier is respectively connected to the anode of the first diode and the first end of the seventh resistor, the output terminal of the second operational amplifier is respectively connected to the cathode of the first diode and the anode of the second diode, the positive input terminal of the third operational amplifier is connected to the cathode of the second diode, and the positive input terminal of the third operational amplifier is respectively grounded through the eighth resistor and the second capacitor, the negative input terminal of the third operational amplifier is connected to the second end of the seventh resistor, the output terminal of the third operational amplifier is connected to the differential unit, and the output terminal of the third operational amplifier is grounded through the third capacitor.

[0023] In one embodiment, the phase processing module includes a fourth operational amplifier, an adjustable resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor and a fourteenth resistor, wherein the positive input terminal of the fourth operational amplifier is grounded through the ninth resistor, and the positive input terminal of the fourth operational amplifier is connected to the control terminal of the adjustable resistor through the tenth resistor, the negative input terminal of the fourth operational amplifier is respectively connected to the sampling module and the primary winding through the eleventh resistor, and the negative input terminal of the fourth operational amplifier is respectively connected to the output terminal of the fourth operational amplifier and the demodulation feedback module through the twelfth resistor, the first end of the adjustable resistor receives the second power supply signal through the thirteenth resistor, and the second end of the adjustable resistor receives the third power supply signal through the fourteenth resistor.

[0024] In one embodiment, the magnetic core includes a DC magnetic core and an AC magnetic core, and the primary winding includes a DC winding and an AC winding, wherein the DC winding is wound on the DC magnetic core, the AC winding is wound on the AC magnetic core, the secondary winding is respectively wound on the DC winding and the AC magnetic core, and the DC winding and the AC winding are respectively connected to the compensation circuit.

[0025] In a second aspect, an embodiment of the present application provides a current measurement system, which includes the zero-flux current sensor and a conductor to be measured as described above.

[0026] The above-mentioned zero-flux current sensor and current measurement system include a magnetic core, a primary winding, a secondary winding, a compensation circuit and a signal processing circuit, wherein the signal processing circuit includes a conditioning module and a signal processing module, and the compensation circuit is used to generate a compensation current according to the current to be measured, so that the secondary winding generates a compensation flux according to the compensation current to offset the bias flux generated by the primary winding according to the current to be measured, and a clamping signal is generated according to the compensation current, and the signal processing module is used to determine the current to be measured according to the clamping signal. In this way, the compensation current can be conditioned by the conditioning module, so that the conditioned clamping signal can meet the signal processing conditions of the signal processing module, so that the signal processing module can capture the clamping signal in a timely and accurate manner, thereby realizing timely and accurate measurement of the current to be measured, avoiding measurement errors caused by the compensation current not meeting the signal processing conditions of the signal processing module, and improving measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] FIG1 is a schematic structural diagram of a zero-flux current sensor according to an embodiment;

[0029] FIG2 is a schematic diagram of the structure of a conditioning module according to an embodiment;

[0030] FIG3 is a partial structural schematic diagram of a zero-flux current sensor according to an embodiment;

[0031] FIG4 is a schematic structural diagram of a zero flux current sensor according to another embodiment;

[0032] FIG5a is a waveform diagram of a first sampling signal according to an embodiment;

[0033] FIG5b is a waveform diagram of a second sampling signal according to an embodiment;

[0034] FIG6 is a schematic diagram of the structure of a target peak demodulation subunit according to an embodiment;

[0035] FIG7 is a schematic diagram of the structure of a phase processing module according to an embodiment;

[0036] FIG8 is a schematic structural diagram of a differential unit according to an embodiment;

[0037] FIG9 is a schematic structural diagram of a feedback unit according to an embodiment;

[0038] FIG10 is a schematic structural diagram of a zero flux current sensor according to another embodiment;

[0039] FIG11 is a partial structural schematic diagram of a zero-flux current sensor according to another embodiment;

[0040] FIG. 12 is a schematic structural diagram of an oscillation module according to an embodiment.

[0041] Description of reference numerals:

[0042] Magnetic core 11, DC magnetic core 111, AC magnetic core 112, primary winding 12, secondary winding 13, compensation circuit 20, oscillation module 21, sampling module 22, phase processing module 23, demodulation feedback module 24, peak demodulation unit 241, first peak demodulation subunit 2411, second peak demodulation subunit 2412, differential unit 242, feedback unit 243, signal processing circuit 30, conditioning module 31, signal processing module 32, filtering unit 321, signal processing unit 322, amplifier circuit 40. DETAILED DESCRIPTION

[0043] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0045] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0046] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0047] It can be understood that “at least one” means one or more, “plurality” means two or more, and “at least a portion of an element” means a part or all of an element.

[0048] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0049] In one embodiment, as shown in FIG. 1 , a zero-flux current sensor is provided, including a magnetic core 11 , a primary winding 12 , a secondary winding 13 , a compensation circuit 20 and a signal processing circuit 30 .

[0050] The primary winding 12 and the secondary winding 13 are respectively wound on the magnetic core 11. The number of turns of the secondary winding 13 is recorded as Ns. The primary winding 12 is used to sense the current to be measured of the conductor to be measured. The compensation circuit 20 is connected to the primary winding 12 and the secondary winding 13 respectively. The compensation circuit 20 is used to generate a compensation current according to the current to be measured, so that the secondary winding 13 generates a compensation flux according to the compensation current to offset the bias flux generated by the primary winding 12 according to the current to be measured. The compensation flux is equal to the bias flux and opposite in direction.

[0051] The signal processing circuit 30 includes a conditioning module 31 and a signal processing module 32. The conditioning module 31 is connected to the secondary winding 13. The conditioning module 31 is used to generate a clamping signal according to the compensation current. The clamping signal satisfies the signal processing condition of the signal processing module 32. The signal processing module 32 is connected to the conditioning module 31. The signal processing module 32 is used to determine the current to be measured according to the clamping signal. Exemplarily, the signal processing module 32 includes a digital signal processing (DSP) chip.

[0052] Among them, the signal processing condition refers to the condition under which the signal processing module 32 can process the signal. Exemplarily, the signal processing condition includes the voltage range and / or current range of the signal input to the signal processing module 32. For example, when the signal processing condition includes the voltage range, the voltage of the clamped signal conforms to the voltage range; when the signal processing condition includes the current range, the current range of the clamped signal includes the current range. In application, the signal processing condition can be specifically determined according to the actual structure of the signal processing module 32, and is not excessively limited here.

[0053] In an embodiment of the present application, the zero-flux current sensor includes a magnetic core 11, a primary winding 12, a secondary winding 13, a compensation circuit 20 and a signal processing circuit 30, wherein the signal processing circuit 30 includes a conditioning module 31 and a signal processing module 32, and the compensation circuit 20 is used to generate a compensation current according to the current to be measured, so that the secondary winding 13 generates a compensation flux according to the compensation current to offset the bias flux generated by the primary winding 12 according to the current to be measured, and a clamping signal is generated according to the compensation current, and the signal processing module 32 is used to determine the current to be measured according to the clamping signal. In this way, the compensation current can be conditioned by the conditioning module 31, so that the conditioned clamping signal can meet the signal processing conditions of the signal processing module 32, so that the signal processing module 32 can capture the clamping signal in a timely and accurate manner, thereby realizing timely and accurate measurement of the current to be measured, avoiding measurement errors caused by the compensation current not meeting the signal processing conditions of the signal processing module 32, and improving measurement accuracy.

[0054] In one embodiment, as shown in FIG2 , the conditioning module 31 includes a first operational amplifier U1, a first capacitor C1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6. The positive input terminal of the first operational amplifier U1 is respectively connected to the first end of the first resistor R1, the first end of the second resistor R2, and the first end of the third resistor R3, the negative input terminal of the first operational amplifier U1 receives the reference signal Vref via the fourth resistor R4, and the negative input terminal of the first operational amplifier U1 is respectively connected to the output terminal of the first operational amplifier U1 and the signal processing module 32 via the fifth resistor R5, the second end of the first resistor R1 is respectively connected to the first end of the sixth resistor R6 and the first end of the first capacitor C1, the second end of the second resistor R2 receives the first power signal VD1, the second end of the third resistor R3 and the second end of the first capacitor C1 are respectively grounded, and the second end of the sixth resistor R6 is connected to the secondary winding 13. The first power supply terminal of the first operational amplifier U1 is used to receive a first power supply signal, and the second power supply terminal of the first operational amplifier U1 is used to receive a second power supply signal, wherein the first power supply signal is greater than the second power supply signal. The first power supply signal and the second power supply signal can be set according to the working requirements of the first operational amplifier U1, and are not specifically limited. For example, the working voltage of the first operational amplifier U1 is -5V~5V, and correspondingly, the first power supply signal is 5V, and the second power supply is -5V.

[0055] In the embodiment of the present application, the conditioning module 31 can generate a clamping signal that meets the signal processing conditions according to the compensation current through the first operational amplifier U1, the first capacitor C1, the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6, that is, the received signal is clamped within the signal processing conditions of the signal processing module 32, avoiding measurement errors caused by the inability to capture the signal in a timely and accurate manner due to the input to the signal processing module 32 not meeting the signal processing conditions, thereby improving the measurement accuracy and timeliness.

[0056] In one embodiment, as shown in FIG3 , the signal processing module 32 includes a filter unit 321 and a signal processing unit 322. The filter unit 321 is connected to the conditioning module 31. The filter unit 321 is used to filter the clamp signal. The signal processing unit 322 is used to determine the current to be measured according to the clamp signal after filtering.

[0057] In the embodiment of the present application, the clamp signal is filtered by the filter unit 321 to filter out interference, so that the signal processing unit 322 can obtain a more accurate current to be measured according to the filtered clamp signal, further improving the measurement accuracy.

[0058] Please continue to refer to FIG. 3. In one embodiment, the filtering unit 321 includes a first inductor L1, a second inductor L2, and a second capacitor C2. The first end of the first inductor L1 is connected to the secondary winding 13, the second end of the first inductor L1 is respectively connected to the first end of the second inductor L2 and the first end of the second capacitor C2, the second end of the second inductor L2 is connected to the conditioning module 31, and the second end of the second capacitor C2 is respectively connected to the secondary winding 13 and the conditioning module 31.

[0059] In the embodiment of the present application, the filtering unit 321 can filter out the ripple in the clamping signal through the first inductor L1, the second inductor L2 and the second capacitor C2. When high-frequency harmonics are input, since the impedance of the filter capacitor branch decreases with the increase of ω, the filter capacitor branch will provide a low-resistance path for the high-frequency harmonics, and the filter inductor branch presents a high impedance, thereby performing parallel impedance shunting, which will further suppress the injection of high-frequency harmonic current components into the signal processing unit 322, so that the signal processing unit 322 can obtain a more accurate current to be measured based on the filtered clamping signal, further improving the measurement accuracy.

[0060] Please continue to refer to FIG3 . In one embodiment, the signal processing unit 322 includes a DSP chip TMS320F28335. Exemplarily, the signal processing condition is that the voltage range is 0-3V. The conditioning module 31 is used to generate a clamping signal according to the compensation current, and the voltage range of the clamping signal is 0-3V.

[0061] In one embodiment, as shown in FIG. 4 , FIG. 5 a and FIG. 5 b , the compensation circuit 20 includes an oscillation module 21 , a sampling module 22 , a phase processing module 23 and a demodulation feedback module 24 .

[0062] The oscillation module 21 is connected to the primary winding 12. The oscillation module 21 is used to self-oscillate according to the current to be measured, and generate an alternating current signal, and transmit it to the primary winding 12. The alternating current signal is a periodic signal. Exemplarily, the alternating current signal includes a sine wave signal.

[0063] The sampling module 22 is connected to the primary winding 12. The sampling module 22 is used to sample the AC signal and output a first sampling signal.

[0064] The phase processing module 23 is connected to the sampling module 22. The phase processing module 23 is used to perform inversion processing on the first sampling signal and generate a second sampling signal. The second sampling signal is different from the first sampling signal in phase, and the phase difference between the second sampling signal and the first sampling signal is 180°.

[0065] The demodulation feedback module 24 is respectively connected to the sampling module 22, the phase processing module 23 and the secondary winding 13. The demodulation feedback module 24 is used to generate a compensation current according to the first sampling signal and the second sampling signal.

[0066] In the embodiment of the present application, the compensation circuit 20 includes an oscillation module 21, a sampling module 22, a phase processing module 23 and a demodulation feedback module 24. The oscillation module 21 can self-oscillate and generate an AC signal according to the current to be measured, and the sampling module 22 can sample the AC signal and output a first sampling signal, and the phase processing module 23 can invert the first sampling signal and generate a second sampling signal, and the demodulation feedback module 24 can generate a compensation current according to the first sampling signal and the second sampling signal. In this way, by inverting the first sampling signal and then processing it, there is no need to set up a rectifier circuit for rectification processing, which eliminates the design requirements of the rectifier circuit, simplifies the circuit structure, and reduces the cost.

[0067] Please continue to refer to FIG. 4 , FIG. 5 a and FIG. 5 b . In one embodiment, the demodulation feedback module 24 includes a peak demodulation unit 241 , a difference unit 242 and a feedback unit 243 .

[0068] The peak demodulation unit 241 is connected to the sampling module 22 and the phase processing module 23 respectively. The peak demodulation unit 241 is used to generate a first peak signal according to the first sampling signal, and to generate a second peak signal according to the second sampling signal. Exemplarily, the first peak signal is the peak value of half a cycle in each cycle of the first sampling signal. Exemplarily, the second peak signal is the peak absolute value of half a cycle in each cycle of the second sampling signal, wherein the first peak signal and the second peak signal correspond to the same time.

[0069] The differential unit 242 is connected to the peak demodulation unit 241. The differential unit 242 is used to generate a peak difference signal according to the first peak signal and the second peak signal. The peak difference signal is the difference between the first peak signal and the second peak signal. The feedback unit 243 is connected to the differential unit 242 and the secondary winding 13 respectively. The feedback unit 243 is used to generate a compensation current according to the peak difference signal to compensate the secondary winding 13 through the compensation current, so that the compensation flux generated by the secondary winding 13 is equal to the bias flux generated by the primary winding 12 and has an opposite direction.

[0070] In the application, the peak demodulation unit 241 can accurately obtain the peak values ​​of the positive and negative half-cycles of each periodic signal flowing through the primary winding 12 by receiving the sampling signals output by the sampling module 22 and the phase processing module 23 respectively, and calculate the difference between the two peak values ​​through the differential unit 242, that is, compare the peak values ​​of the two input waveforms, and keep capturing these peak values ​​for a period of time (the time period is usually designed to be longer than the period of the input signal), so as to transmit the compensation current to the secondary winding 13 through the feedback unit 243 for compensation adjustment, thereby ensuring that the compensation flux on the secondary winding 13 is equal to the bias flux generated by the primary winding 12 and has the opposite direction, thereby achieving precise flux balance.

[0071] In the embodiment of the present application, the peak values ​​of the two half-cycles of each cycle of the sampling signal (including the first sampling signal and the second sampling signal) sampled and obtained by the primary winding 12 are differentially calculated, that is, the peak value of the half cycle of the first sampling signal is DC detected, and the peak value of the half cycle of the second sampling signal is DC detected, wherein the second sampling signal is obtained after the first sampling signal is inverted, that is, the peak difference of the positive half-wave and the negative half-wave of each cycle of the signal flowing through the primary winding 12 is DC detected respectively, therefore, it is not necessary to set at least two DC windings, at least two DC magnetic cores and at least two sampling resistors to realize DC detection, which reduces the number of parts, simplifies the circuit structure, reduces the cost, and reduces the volume. In addition, the absolute value of the peak value and the valley value of each half-wave is directly differentially compared, wherein the absolute value of the valley value is obtained by first inverting the entire signal and then taking its peak value, without first rectifying the half-wave and calculating the effective value, eliminating the design requirements of the rectification and filtering circuits, reducing the number of circuits, and simplifying the sensor structure.

[0072] In addition, in the embodiment of the present application, there is no need to change the structure of the peak demodulation unit 241. It is only necessary to adjust the parameters of the peak demodulation unit 241 so that the peak holding time is greater than half the oscillation period (phase difference of 180°) of the corresponding sampling signal. The structure is simple.

[0073] In one embodiment, as shown in FIG6 , the peak demodulation unit 241 includes a first peak demodulation subunit 2411 and a second peak demodulation subunit 2412 . The first peak demodulation subunit 2411 is connected to the sampling module 22 . The second peak demodulation subunit 2412 is connected to the phase processing module 23 .

[0074] The target peak demodulation subunit includes at least one of a first peak demodulation subunit 2411 and a second peak demodulation subunit 2412. The target peak demodulation subunit includes a second operational amplifier U2, a third operational amplifier U3, a first diode D1, a second diode D2, a third capacitor C3, a fourth capacitor C4, a seventh resistor R7 and an eighth resistor R8. The positive input terminal of the second operational amplifier U2 receives the target sampling signal. The target sampling signal includes at least one of the first sampling signal and the second sampling signal. When the target peak demodulation subunit is the first peak demodulation subunit 2411, the target sampling signal includes the first sampling signal, that is, the positive input terminal of the second operational amplifier U2 is respectively connected to the sampling module 22 and the primary winding 12. When the target peak demodulation subunit is the second peak demodulation subunit 2412, the target sampling signal includes the second sampling signal, that is, the positive input terminal of the second operational amplifier U2 is connected to the phase processing module 23. The negative input terminal of the second operational amplifier U2 is respectively connected to the anode of the first diode D1 and the first end of the seventh resistor R7, the output terminal of the second operational amplifier U2 is respectively connected to the cathode of the first diode D1 and the anode of the second diode D2, the positive input terminal of the third operational amplifier U3 is connected to the cathode of the second diode D2, and the positive input terminal of the third operational amplifier U3 is respectively grounded through the eighth resistor R8 and the third capacitor C3, the negative input terminal of the third operational amplifier U3 is connected to the second end of the seventh resistor R7, the output terminal of the third operational amplifier U3 is connected to the differential unit 242, and the output terminal of the third operational amplifier U3 is grounded through the fourth capacitor C4.

[0075] In applications, the first peak demodulation subunit 2411 and the second peak demodulation subunit 2412 can be set to the same circuit structure or different circuit structures. The specific settings can be made according to requirements and are not limited too much here.

[0076] In the embodiment of the present application, a DC detection is performed on the peak value of half a cycle of the first sampling signal by the first peak demodulation subunit 2411, and a DC detection is performed on the peak value of half a cycle of the second sampling signal by the second peak demodulation subunit 2412, which replaces the processing process of rectifying the sampling signal and then taking the effective value in the related art. Therefore, there is no need to set up a rectification and filtering circuit, nor is there a need to set up at least two DC windings, at least two DC magnetic cores and at least two sampling resistors to achieve DC detection, which reduces the number of parts, simplifies the circuit structure, reduces the cost, and reduces the size.

[0077] In one embodiment, as shown in FIG7 , the phase processing module 23 includes a fourth operational amplifier U4, an adjustable resistor VR1, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13 and a fourteenth resistor R14. Among them, the positive input terminal of the fourth operational amplifier U4 is grounded through the ninth resistor R9, and the positive input terminal of the fourth operational amplifier U4 is connected to the control terminal of the adjustable resistor VR1 through the tenth resistor R10, the negative input terminal of the fourth operational amplifier U4 is connected to the sampling module 22 and the primary winding 12 through the eleventh resistor R11, and the negative input terminal of the fourth operational amplifier U4 is connected to the output terminal of the fourth operational amplifier U4 and the demodulation feedback module 24 through the twelfth resistor R12, the first end of the adjustable resistor VR1 receives the second power signal VD2 through the thirteenth resistor R13, and the second end of the adjustable resistor VR2 receives the third power signal VE1 through the fourteenth resistor R14. Among them, the second power signal VD2 is greater than the third power signal VE1.

[0078] In application, a DC bias signal can be introduced into the phase processing module 23 by adjusting the resistance of the adjustable resistor VR1. The DC bias signal can change the amplification factor of the phase processing module 23, and the amplification factor of the phase processing module 23 can also be adjusted by fine-tuning the resistance of the eleventh resistor R11 and the twelfth resistor R12. In addition, the peak difference signal can be corrected, that is, the deviation between the absolute value of the positive half-wave peak value and the negative half-wave peak value of the signal flowing through the primary winding 12 can be corrected, thereby ensuring the accuracy and stability of the signal.

[0079] In one embodiment, as shown in FIG8 , the differential unit 242 includes a fifth operational amplifier U5, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, and an eighteenth resistor R18. Among them, the positive input terminal of the fifth operational amplifier U5 is grounded through the fifteenth resistor R15. The positive input terminal of the fifth operational amplifier U5 is connected to the first output terminal (e.g., the first peak demodulation subunit 2411) of the peak demodulation unit 241 through the sixteenth resistor R16, and the negative input terminal of the fifth operational amplifier U5 is connected to the second output terminal (e.g., the second peak demodulation subunit 2412) of the peak demodulation unit 241 through the seventeenth resistor R17. And the negative input terminal of the fifth operational amplifier U5 is connected to the output terminal of the fifth operational amplifier U5 and the feedback unit 243 through the eighteenth resistor R18. Among them, the first output terminal of the peak demodulation unit 241 is used to output the first peak signal, and the second output terminal of the peak demodulation unit 241 is used to output the second peak signal.

[0080] In one embodiment, as shown in Figure 9, the feedback unit 243 includes a feedback power amplifier PA and a fifth capacitor C5, wherein the positive input terminal of the feedback power amplifier PA is grounded, the negative input terminal of the feedback power amplifier PA is respectively connected to the first end of the fifth capacitor C5 and the differential unit 242, and the output end of the feedback power amplifier PA is respectively connected to the second end of the fifth capacitor C5 and the first end of the secondary winding 13.

[0081] In one embodiment, as shown in Fig. 10, the magnetic core 11 includes a DC magnetic core 111 and an AC magnetic core 112, and the primary winding 12 includes a DC winding T1 and an AC winding T2. The secondary winding 13 is wound around the DC winding T1 and the AC magnetic core 112, respectively.

[0082] The DC winding T1 is wound on the DC magnetic core 111. The DC winding T1 is connected to the compensation circuit 20. Exemplarily, the first end of the DC winding T1 is connected to the oscillation module 21, and the second end of the DC winding T1 is connected to the sampling module 22 and the demodulation feedback module 24 respectively.

[0083] The AC winding T2 is wound on the AC magnetic core 112. The AC winding T2 is connected to the compensation circuit 20. Exemplarily, the zero flux current sensor also includes a first sampling resistor Rs1 and a second sampling resistor Rs2, wherein the first end of the AC winding T2 is grounded, the second end of the AC winding T2 is connected to the first end of the first sampling resistor Rs1, and the second end of the first sampling resistor Rs1 is connected to the demodulation feedback module 24 via the second sampling resistor Rs2. Specifically, the second end of the first sampling resistor Rs1 is respectively connected to the first end of the second sampling resistor Rs2 and the negative input end of the feedback power amplifier PA in the feedback unit 243, and the second end of the second sampling resistor Rs2 is connected to the output end of the fifth operational amplifier U5 in the differential unit 242.

[0084] Please continue to refer to FIG. 10. In one embodiment, the sampling module 22 includes a third sampling resistor Rs3, and a first end of the third sampling resistor Rs3 is grounded. A second end of the third sampling resistor Rs3 is respectively connected to the primary winding 12 and the demodulation feedback module 24. Exemplarily, a second end of the third sampling resistor Rs3 is respectively connected to the DC winding T1 and the first peak demodulation subunit 2411.

[0085] In one embodiment, as shown in FIG11 , the zero flux current sensor further includes an amplifier circuit 40. The amplifier circuit 40 is connected to the secondary winding 13 and the conditioning module 31 respectively, and the amplifier circuit 40 is used to amplify the compensation current. The conditioning module 31 is used to generate a clamping signal according to the amplified compensation current.

[0086] Exemplarily, the amplifier circuit 40 includes a sixth operational amplifier U6, a nineteenth resistor R19, a twentieth resistor R20, a twenty-first resistor R21, a twenty-second resistor R22 and a twenty-third resistor R23. The positive input terminal of the sixth operational amplifier U6 is grounded via the nineteenth resistor R19 and the twentieth resistor R20, respectively. The negative input terminal of the sixth operational amplifier U6 is connected to the first end of the secondary winding 13 and the twenty-second resistor R22 via the twenty-first resistor R21, respectively. The negative input terminal of the sixth operational amplifier U6 is connected to the output terminal of the sixth operational amplifier U6 via the twenty-third resistor R23, and the second end of the twenty-second resistor R22 is grounded.

[0087] In the embodiment of the present application, the zero-flux current sensor also amplifies the compensation current through the amplifier circuit 40, so that the signal processing circuit 30 can accurately measure the current to be measured based on the amplified compensation current, and can also ensure the stable operation of the circuit.

[0088] In one embodiment, as shown in FIG12 , the oscillation module 21 includes a seventh operational amplifier U7, a sixth capacitor C6, a seventh capacitor C7, a third diode D3, a fourth diode D4, a twenty-fourth resistor R24, a twenty-fifth resistor R25, a twenty-sixth resistor R26, a twenty-seventh resistor R27, and a twenty-eighth resistor R28. The positive input terminal of the seventh operational amplifier U7 is respectively connected to the first end of the sixth capacitor C6, the first end of the twenty-fourth resistor R24, and the first end of the twenty-fifth resistor R25, the negative input terminal of the seventh operational amplifier U7 is respectively connected to the second end of the twenty-fifth resistor R25, the first end of the twenty-sixth resistor R26, and the first end of the twenty-seventh resistor R27, and the output terminal of the seventh operational amplifier U7 is respectively connected to the primary winding 12, the first end of the seventh capacitor C7, the cathode of the third diode D3, the anode of the fourth diode D4, and the second end of the twenty-seventh resistor R27. The second end of the twenty-fourth resistor R24 ​​is respectively connected to the second end of the sixth capacitor C6 and the first end of the twenty-eighth resistor R28, and the second end of the twenty-eighth resistor R28 is connected to the second end of the seventh capacitor C7. The second end of the twenty-sixth resistor R26 is connected to the anode of the third diode D3 and the cathode of the fourth diode D4 respectively.

[0089] In the embodiment of the present application, the oscillation module 21 can generate an AC signal such as a sinusoidal wave signal through the seventh operational amplifier U7, the sixth capacitor C6, the seventh capacitor C7, the third diode D3, the fourth diode D4, the twenty-fourth resistor R24, the twenty-fifth resistor R25, the twenty-sixth resistor R26, the twenty-seventh resistor R27, and the twenty-eighth resistor R28, and transmit it to the primary winding 12 such as the DC winding T1 to achieve zero flux current detection.

[0090] Please continue to refer to Figures 1 to 12. In one embodiment, a zero flux current sensor is provided, including a DC core 111, an AC core 112, a DC winding T1, an AC winding T2, a secondary winding 13, a compensation circuit 20, an amplifier circuit 40, and a signal processing circuit 30. The compensation circuit 20 includes an oscillation module 21, a phase processing module 23, and a demodulation feedback module 24. The demodulation feedback module 24 includes a peak demodulation unit 241, a differential unit 242, and a feedback unit 243. The signal processing circuit 30 includes a conditioning module 31, a filtering module, and a signal processing module 32.

[0091] Specifically, the zero flux current sensor includes a DC core 111, an AC core 112, a DC winding T1, an AC winding T2, a secondary winding 13, sampling resistors Rs1-Rs3, resistors R1-R28, capacitors C1-C7, inductors L1 and L2, diodes D1-D4, operational amplifiers U1-U7, feedback power amplifiers PA, adjustable potentiometer VR1 and DSP chip TMS320F28335. The specific structure can be found in the above text and related drawings, and will not be repeated here.

[0092] In the embodiment of the present application, the zero-flux current sensor can capture the clamping signal in a timely and accurate manner, and can also filter out interference, thereby realizing timely and accurate measurement of the current to be measured, avoiding measurement errors caused by the compensation current not meeting the signal processing conditions, and improving the measurement accuracy; and, there is no need to set up a rectifier circuit for rectification processing, which eliminates the design requirements of the rectifier circuit, simplifies the circuit structure, and reduces the cost; in addition, there is no need to set up at least two DC windings, at least two DC magnetic cores, and at least two sampling resistors to realize DC detection, which reduces the number of parts, further simplifies the circuit structure, reduces the cost, and reduces the volume.

[0093] Based on the same inventive concept, the embodiment of the present application also provides a current measurement system, which includes a zero flux current sensor and a conductor to be measured. The zero flux current sensor is used to measure the current to be measured on the conductor to be measured. The specific introduction of the zero flux current sensor is detailed in the above-mentioned related content, which will not be repeated here.

[0094] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0095] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0096] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A zero flux current sensor, characterized in that: include: A magnetic core, a primary winding and a secondary winding, wherein the primary winding and the secondary winding are respectively wound on the magnetic core, and the primary winding is used to sense the current to be measured of the conductor to be measured; a compensation circuit, connected to the primary winding and the secondary winding respectively, for generating a compensation current according to the current to be measured, so that the secondary winding generates a compensation flux according to the compensation current to offset the bias flux generated by the primary winding according to the current to be measured; The signal processing circuit includes a conditioning module and a signal processing module, wherein the conditioning module is connected to the secondary winding, the conditioning module is used to generate a clamping signal according to the compensation current, the clamping signal meets the signal processing condition of the signal processing module, the signal processing module is connected to the conditioning module, and the signal processing module is used to determine the current to be measured according to the clamping signal.

2. The zero flux current sensor according to claim 1, characterized in that: The conditioning module includes a first operational amplifier, a first capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor and a sixth resistor, wherein the positive input terminal of the first operational amplifier is respectively connected to the first end of the first resistor, the first end of the second resistor and the first end of the third resistor, the negative input terminal of the first operational amplifier receives a reference signal via the fourth resistor, and the negative input terminal of the first operational amplifier is respectively connected to the output terminal of the first operational amplifier and the signal processing module via the fifth resistor, the second end of the first resistor is respectively connected to the first end of the sixth resistor and the first end of the first capacitor, the second end of the second resistor receives a first power supply signal, the second end of the third resistor and the second end of the first capacitor are respectively grounded, and the second end of the sixth resistor is connected to the secondary winding.

3. The zero flux current sensor according to claim 1, characterized in that: The signal processing module includes a filtering unit and a signal processing unit, wherein the filtering unit is connected to the conditioning module, the filtering unit is used to filter the clamping signal, and the signal processing unit is used to determine the current to be measured according to the filtered clamping signal.

4. The zero flux current sensor according to claim 3, characterized in that: The filtering unit includes a first inductor, a second inductor and a second capacitor, wherein the first end of the first inductor is connected to the conditioning module, the second end of the first inductor is respectively connected to the first end of the second inductor and the second end of the second capacitor, the second end of the second inductor is connected to the signal processing unit, and the second end of the second capacitor is respectively connected to the conditioning module and the signal processing unit.

5. The zero flux current sensor according to any one of claims 1 to 4, characterized in that: The compensation circuit comprises: an oscillation module, connected to the primary winding, and configured to self-oscillate according to the current to be measured and generate an alternating current signal; A sampling module, connected to the primary winding, for sampling the AC signal and outputting a first sampling signal; A phase processing module, connected to the sampling module, configured to perform inversion processing on the first sampling signal and generate a second sampling signal; A demodulation feedback module is connected to the sampling module, the phase processing module and the secondary winding respectively, and is used to generate the compensation current according to the first sampling signal and the second sampling signal.

6. The zero flux current sensor according to claim 5, characterized in that: The demodulation feedback module comprises: a peak demodulation unit, connected to the sampling module and the phase processing module respectively, and configured to generate a first peak signal according to the first sampling signal, and generate a second peak signal according to the second sampling signal; a difference unit, connected to the peak demodulation unit, and configured to generate a peak difference signal according to the first peak signal and the second peak signal; A feedback unit is connected to the differential unit and the secondary winding respectively, and is used to generate the compensation current according to the peak difference signal.

7. The zero flux current sensor according to claim 6, characterized in that: The peak demodulation unit includes a first peak demodulation subunit and a second peak demodulation subunit, the first peak demodulation subunit is connected to the sampling module, and the second peak demodulation subunit is connected to the phase processing module; The target peak demodulation subunit includes at least one of the first peak demodulation subunit and the second peak demodulation subunit, and the target peak demodulation subunit includes a second operational amplifier, a third operational amplifier, a first diode, a second diode, a second capacitor, a third capacitor, a seventh resistor and an eighth resistor, wherein the positive input terminal of the second operational amplifier receives a target sampling signal, and the target sampling signal includes at least one of the first sampling signal and the second sampling signal, the negative input terminal of the second operational amplifier is respectively connected to the anode of the first diode and the first end of the seventh resistor, the output terminal of the second operational amplifier is respectively connected to the cathode of the first diode and the anode of the second diode, the positive input terminal of the third operational amplifier is connected to the cathode of the second diode, and the positive input terminal of the third operational amplifier is respectively grounded through the eighth resistor and the second capacitor, the negative input terminal of the third operational amplifier is connected to the second end of the seventh resistor, the output terminal of the third operational amplifier is connected to the differential unit, and the output terminal of the third operational amplifier is grounded through the third capacitor.

8. The zero flux current sensor according to claim 5, characterized in that: The phase processing module includes a fourth operational amplifier, an adjustable resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor and a fourteenth resistor, wherein the positive input terminal of the fourth operational amplifier is grounded through the ninth resistor, and the positive input terminal of the fourth operational amplifier is connected to the control terminal of the adjustable resistor through the tenth resistor, the negative input terminal of the fourth operational amplifier is respectively connected to the sampling module and the primary winding through the eleventh resistor, and the negative input terminal of the fourth operational amplifier is respectively connected to the output terminal of the fourth operational amplifier and the demodulation feedback module through the twelfth resistor, the first end of the adjustable resistor receives the second power supply signal through the thirteenth resistor, and the second end of the adjustable resistor receives the third power supply signal through the fourteenth resistor.

9. The zero-flux current sensor according to any one of claims 1 to 4, characterized in that: The magnetic core includes a DC magnetic core and an AC magnetic core, and the primary winding includes a DC winding and an AC winding, wherein the DC winding is wound on the DC magnetic core, the AC winding is wound on the AC magnetic core, the secondary winding is respectively wound on the DC winding and the AC magnetic core, and the DC winding and the AC winding are respectively connected to the compensation circuit.

10. A current measurement system, characterized in that: The current measurement system comprises the zero-flux current sensor as claimed in any one of claims 1 to 9 and a conductor to be measured.

Images