Current measuring circuit

Abstract

The invention relates to a current measuring circuit. The current measuring circuit comprises a current comparison circuit and a high-frequency compensation circuit, wherein the current comparison circuit and the high-frequency compensation circuit are connected in parallel; the current comparison circuit is connected with the first magnetic core; the high-frequency compensation circuit is connected with the second magnetic core; the high-frequency compensation circuit is used for eliminating an interference signal in the current to be measured to obtain a target current to be measured; the to-be-measured current is the current from the second magnetic core to the first magnetic core; and the current comparison circuit is used for detecting the target current to be detected. The high-frequency compensation circuit in the embodiment of the application can eliminate the high-frequency interference signal in the current to be measured, and the current comparison circuit can perform current detection on the target current to be measured in which the high-frequency interference signal is eliminated, so that the current measurement circuit in the embodiment of the application can be used for measuring the current of the target current to be measured. Current measurement is accurately carried out on the current of the second magnetic core pointing to the first magnetic core.

Description

Technical Field

[0001] The present application relates to the field of circuit technology, and in particular to a current measurement circuit. Background Art

[0002] With the development of circuit technology, the demand for current measurement is increasing. At present, current measurement technology can be widely used in feedback control, leakage current monitoring, electrical and electronic systems. Based on this, various types of current sensors have been produced, such as fluxgate current sensor. Fluxgate current sensor is a sensor designed and manufactured based on the principle of fluxgate effect. Fluxgate sensor can measure the current in the circuit by detecting the change in resistivity.

[0003] However, the current measurement circuit based on the fluxgate current sensor currently has the problem of low measurement accuracy. Summary of the invention

[0004] Based on this, it is necessary to provide a current measurement circuit that can improve the accuracy of current measurement in order to solve the above technical problems.

[0005] In a first aspect, the present application provides a current measurement circuit, the current measurement circuit comprising a current comparison circuit and a high-frequency compensation circuit, the current comparison circuit and the high-frequency compensation circuit are connected in parallel; the current comparison circuit is connected to a first magnetic core, and the high-frequency compensation circuit is connected to a second magnetic core;

[0006] The high-frequency compensation circuit is used to eliminate interference signals in the current to be measured to obtain a target current to be measured; the current to be measured is the current directed from the second magnetic core to the first magnetic core;

[0007] The current comparison circuit is used to detect the target current to be measured.

[0008] In one embodiment, the current comparison circuit includes a first current detection subcircuit, a second current detection subcircuit and a comparison subcircuit, and the first current detection subcircuit and the second current detection subcircuit are both connected to the first magnetic core;

[0009] The first current detection subcircuit and the second current detection subcircuit are connected in parallel, the first end of the first current detection subcircuit and the first end of the second current detection subcircuit are both connected to the first end of the comparison subcircuit, and the second end of the first current detection subcircuit, the second end of the second current detection subcircuit, and the second end of the comparison subcircuit are all grounded.

[0010] In one embodiment, the first current detection subcircuit includes a first winding, a first winding resistor and a first detection resistor connected in series, the first winding is connected to the first magnetic core, one end of the first winding is connected to the first end of the comparison subcircuit, and one end of the first detection resistor is grounded.

[0011] In one embodiment, the second current detection subcircuit includes a second winding, a second winding resistor and a second detection resistor connected in series, the second winding is connected to the first magnetic core, one end of the second winding is connected to the first end of the comparison subcircuit, and one end of the second detection resistor is grounded.

[0012] In one of the embodiments, the comparison subcircuit includes an operational amplifier, a first resistor and a second resistor;

[0013] The negative input terminal of the operational amplifier is arranged between the first winding resistor and the first detection resistor, the positive input terminal of the operational amplifier is arranged between one end of the first resistor and one end of the second resistor, the output terminal of the operational amplifier is connected to the other end of the second resistor, one end of the first winding, and one end of the second winding, and the other end of the first resistor is grounded;

[0014] The operational amplifier is used to detect the target current to be measured according to the duty cycle of the output signal.

[0015] In one embodiment, the high-frequency compensation circuit includes an inverter and a compensation circuit connected in series, one end of the inverter is connected to one end of the current comparison circuit, and one end of the compensation circuit is grounded; the compensation circuit is connected to the second magnetic core;

[0016] The compensation circuit is used to generate a magnetic flux with the same magnitude and opposite direction as that of the current comparison circuit, and eliminate the interference signal in the current to be measured according to the magnetic flux.

[0017] In one of the embodiments, the compensation circuit includes a first compensation subcircuit and a second compensation subcircuit connected in parallel;

[0018] The first compensation subcircuit and the second compensation subcircuit are used to respectively generate a first magnetic flux that is equal in magnitude and opposite in direction to the first current detection subcircuit, and a second magnetic flux that is equal in magnitude and opposite in direction to the second current detection subcircuit, and eliminate interference signals in the current to be measured based on the first magnetic flux and the second magnetic flux.

[0019] In one embodiment, the first compensation subcircuit includes a third winding, a third winding resistor and a third detection resistor connected in series, the third winding is connected to the second magnetic core, one end of the third winding is connected to the other end of the inverter, and one end of the third detection resistor is grounded.

[0020] In one embodiment, the second compensation subcircuit includes a fourth winding, a fourth winding resistor and a fourth detection resistor connected in series, the fourth winding is connected to the second magnetic core, one end of the fourth winding is connected to the other end of the inverter, and one end of the fourth detection resistor is grounded.

[0021] In one embodiment, the third winding is the same as the first winding, the third winding resistance is the same as the first winding resistance, and the third detection resistance is the same as the first detection resistance; the fourth winding is the same as the second winding, the fourth winding resistance is the same as the second winding resistance, and the fourth detection resistance is the same as the second detection resistance.

[0022] The above-mentioned current measurement circuit includes a current comparison circuit and a high-frequency compensation circuit, and the current comparison circuit and the high-frequency compensation circuit are connected in parallel; the current comparison circuit is connected to the first magnetic core, and the high-frequency compensation circuit is connected to the second magnetic core; the high-frequency compensation circuit is used to eliminate the interference signal in the current to be measured and obtain the target current to be measured; the current to be measured is the current from the second magnetic core to the first magnetic core; the current comparison circuit is used to detect the target current to be measured. The high-frequency compensation circuit in the embodiment of the present application can eliminate the high-frequency interference signal in the current to be measured, and the current comparison circuit can perform current detection on the target current to be measured with the high-frequency interference signal eliminated. In this way, the current measurement circuit in the embodiment of the present application can be used to accurately measure the current from the second magnetic core to the first magnetic core. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0024] FIG1 is a schematic diagram of the structure of a current measurement circuit in one embodiment;

[0025] FIG2 is a schematic diagram of the structure of a current measurement circuit including a current comparison circuit in one embodiment;

[0026] FIG3 is a circuit diagram of a current comparison circuit in one embodiment;

[0027] FIG4 is a schematic diagram of a circuit corresponding to a fluxgate sensor in the related art in one embodiment;

[0028] FIG5 is a schematic diagram of the structure of a current measurement circuit including a high-frequency compensation circuit in one embodiment;

[0029] FIG6 is a circuit diagram of a high frequency compensation circuit in one embodiment;

[0030] FIG. 7 is a circuit diagram of a current measurement circuit in another embodiment.

[0031] Description of reference numerals:

[0032] Current comparison circuit: 1; high-frequency compensation circuit: 2; first magnetic core: W1; second magnetic core: W2; current to be measured: Ip; first current detection subcircuit: 11; second current detection subcircuit: 12; comparison subcircuit: 13; first winding: Ws1; first winding resistance: Rc1; first detection resistance: R3; second winding: Ws2; second winding resistance: Rc2; second detection resistance: R4; operational amplifier: CMP1; first resistance: R1; second resistance: R2; inverter: 21; compensation circuit: 22; first compensation subcircuit: 221; second compensation subcircuit: 222; third winding: Ws3; third winding resistance: Rc3; third detection resistance: R5; fourth winding: Ws4; fourth winding resistance: Rc4; fourth detection resistance: R6. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0035] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0036] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0037] With the development of circuit technology, the demand for current measurement is increasing, and more and more current forms need to be detected. At present, current measurement technology can be widely used in feedback control, leakage current monitoring, electrical and electronic systems. Based on this, various types of current sensors have been produced, such as fluxgate current sensor. Fluxgate current sensor is a sensor designed and manufactured based on the principle of fluxgate effect. Fluxgate effect refers to the phenomenon that the resistivity of magnetic materials will change under the action of an external magnetic field. Therefore, fluxgate sensor can measure the current in the circuit by detecting the change in resistivity.

[0038] However, the traditional self-excited fluxgate current sensor measures current by using an RL multivibrator composed of a nonlinear mutual inductor and an operational amplifier, and the range of the traditional self-excited fluxgate current sensor is only 0.5A. Due to the insufficient range of the traditional self-excited fluxgate current sensor, the traditional self-excited fluxgate current sensor cannot be widely used in high-power electrical equipment. In addition, the traditional fluxgate sensor may be interfered by the magnetic field, and the high-frequency interference signal in the excitation current may be coupled to other windings, resulting in the presence of high-frequency interference signals in the measured current, and ultimately resulting in an inaccurate output signal, thereby affecting the accuracy and stability of the fluxgate sensor. Therefore, the current measurement circuit based on the fluxgate current sensor currently has the problem of low measurement accuracy.

[0039] Based on this, an embodiment of the present application provides a current measurement circuit.

[0040] In one embodiment, as shown in FIG. 1 , a current measurement circuit is provided, the current measurement circuit comprising a current comparison circuit 1 and a high-frequency compensation circuit 2, the current comparison circuit 1 and the high-frequency compensation circuit 2 are connected in parallel; the current comparison circuit 1 is connected to a first magnetic core W1, and the high-frequency compensation circuit 2 is connected to a second magnetic core W2;

[0041] The high-frequency compensation circuit 2 is used to eliminate the interference signal in the current to be measured Ip to obtain the target current to be measured; the current to be measured Ip is the current directed from the second magnetic core W2 to the first magnetic core W1;

[0042] The current comparison circuit 1 is used to detect the target current to be measured.

[0043] In the embodiment of the present application, the current measurement circuit includes a current comparison circuit 1 and a high-frequency compensation circuit 2 connected in parallel, one end of the current comparison circuit 1 and one end of the high-frequency compensation circuit 2 are both grounded, the other end of the current comparison circuit 1 and the other end of the high-frequency compensation circuit 2 are connected, the current comparison circuit 1 is connected to the first magnetic core W1, and the high-frequency compensation circuit 2 is connected to the second magnetic core W2, so that a current to be measured Ip is generated between the first magnetic core W1 and the second magnetic core W2, and the direction of the current to be measured Ip is the direction from the second magnetic core W2 to the first magnetic core W1, and due to the magnetic field interference around the current measurement circuit, there is a high-frequency interference signal in the current to be measured Ip. Based on this, the high-frequency interference signal in the current to be measured Ip can be eliminated by the high-frequency compensation circuit 2, and the current comparison circuit 1 can be used to perform current detection on the target current to be measured from which the high-frequency interference signal has been eliminated.

[0044] In the above-mentioned current measurement circuit, the current measurement circuit includes a current comparison circuit and a high-frequency compensation circuit, and the current comparison circuit and the high-frequency compensation circuit are connected in parallel; the current comparison circuit is connected to the first magnetic core, and the high-frequency compensation circuit is connected to the second magnetic core; the high-frequency compensation circuit is used to eliminate the interference signal in the current to be measured and obtain the target current to be measured; the current to be measured is the current from the second magnetic core to the first magnetic core; the current comparison circuit is used to detect the target current to be measured. The high-frequency compensation circuit in the embodiment of the present application can eliminate the high-frequency interference signal in the current to be measured, and the current comparison circuit can perform current detection on the target current to be measured with the high-frequency interference signal eliminated. In this way, the current measurement circuit in the embodiment of the present application can be used to accurately measure the current from the second magnetic core to the first magnetic core.

[0045] In one embodiment, as shown in FIG. 2 , the current comparison circuit 1 includes a first current detection subcircuit 11 , a second current detection subcircuit 12 and a comparison subcircuit 13 , and the first current detection subcircuit 11 and the second current detection subcircuit 12 are both connected to the first magnetic core W1 ;

[0046] The first current detection subcircuit 11 and the second current detection subcircuit 12 are connected in parallel, the first end of the first current detection subcircuit 11 and the first end of the second current detection subcircuit 12 are both connected to the first end of the comparison subcircuit 13, and the second end of the first current detection subcircuit 11, the second end of the second current detection subcircuit 12, and the second end of the comparison subcircuit 13 are all grounded.

[0047] In the embodiment of the present application, the current comparison circuit 1 includes a first current detection subcircuit 11, a second current detection subcircuit 12 and a comparison subcircuit 13. The first current detection subcircuit 11 and the second current detection subcircuit 12 are both connected to the first magnetic core W1, the first current detection subcircuit 11 and the second current detection subcircuit 12 are connected in parallel, the first end of the first current detection subcircuit 11 and the first end of the second current detection subcircuit 12 are both connected to the first end of the comparison subcircuit 13, and the second end of the first current detection subcircuit 11, the second end of the second current detection subcircuit 12, and the second end of the comparison subcircuit 13 are all grounded. Optionally, the circuit structures of the first current detection subcircuit 11 and the second current detection subcircuit 12 may be the same, or may be different, which is not limited in the embodiment of the present application.

[0048] In one embodiment, as shown in FIG. 3 , the first current detection subcircuit 11 includes a first winding Ws1, a first winding resistor Rc1 and a first detection resistor R3 connected in series, the first winding Ws1 is connected to the first magnetic core W1, one end of the first winding Ws1 is connected to the first end of the comparison subcircuit 13, and one end of the first detection resistor R3 is grounded.

[0049] In one embodiment, as shown in FIG. 3 , the second current detection subcircuit 12 includes a second winding Ws2, a second winding resistor Rc2, and a second detection resistor R4 connected in series, the second winding Ws2 is connected to the first magnetic core W1, one end of the second winding Ws2 is connected to the first end of the comparison subcircuit 13, and one end of the second detection resistor R4 is grounded.

[0050] In one embodiment, as shown in FIG. 3 , the comparison subcircuit 13 includes an operational amplifier CMP1 , a first resistor R1 , and a second resistor R2 ;

[0051] The negative input terminal of the operational amplifier CMP1 is arranged between the first winding resistor Rc1 and the first detection resistor R3, the positive input terminal of the operational amplifier CMP1 is arranged between one end of the first resistor R1 and one end of the second resistor R2, the output terminal of the operational amplifier CMP1 is connected to the other end of the second resistor R2, one end of the first winding Ws1, and one end of the second winding Ws2, and the other end of the first resistor R1 is grounded;

[0052] Operational amplifier CMP1 is used to output the signal V EX1 The duty cycle of the target current to be measured is detected.

[0053] The first winding resistance Rc1 is the internal resistance of the coil of the first winding, the second winding resistance Rc2 is the internal resistance of the coil of the second winding, the first magnetic core W1 is the main magnetic core, the second magnetic core W2 is the auxiliary magnetic core, V EX1 is the output signal of the operational amplifier CMP1.

[0054] In the embodiment of the present application, the first current detection subcircuit 11 includes a first winding Ws1, a first winding resistor Rc1 and a first detection resistor R3 connected in series, the first winding Ws1 is connected to the first magnetic core W1, for example, the first winding Ws1 is wound on the first magnetic core W1, and the number of turns of the first winding Ws1 is N1. One end of the first winding Ws1 is connected to the output end of the operational amplifier CMP1 in the comparison subcircuit 13, the other end of the first winding Ws1 is connected to one end of the first winding resistor Rc1, the other end of the first winding resistor Rc1 is connected to the other end of the first detection resistor R3, and one end of the first detection resistor R3 is grounded.

[0055] The second current detection subcircuit 12 includes a second winding Ws2, a second winding resistor Rc2, and a second detection resistor R4 connected in series. The second winding Ws2 is connected to the first magnetic core W1. For example, the second winding Ws2 is wound on the first magnetic core W1, and the number of turns of the second winding Ws2 is N2. One end of the second winding Ws2 is connected to the output end of the operational amplifier CMP1 of the comparison subcircuit 13, the other end of the second winding Ws2 is connected to one end of the second winding resistor Rc2, the other end of the second winding resistor Rc2 is connected to the other end of the second detection resistor R4, and one end of the second detection resistor R4 is grounded.

[0056] The above-mentioned comparison subcircuit 13 includes an operational amplifier CMP1, a first resistor R1 and a second resistor R2, wherein the negative input terminal of the operational amplifier CMP1 is arranged between the other end of the first winding resistor Rc1 and the other end of the first detection resistor R3, the positive input terminal of the operational amplifier CMP1 is arranged between one end of the first resistor R1 and one end of the second resistor R2, the output terminal of the operational amplifier CMP1 is connected to the other end of the second resistor R2, one end of the first winding Ws1, and one end of the second winding Ws2, and the other end of the first resistor R1 is grounded, that is, the other end of the first resistor R1 is connected to the analog ground.

[0057] In the embodiment of the present application, the operational amplifier CMP1 in the current comparison circuit can be used to output the output signal V EX1 The duty cycle of the target current to be measured is detected. The specific working principle is as follows:

[0058] In the initial state, when no current flows through the first winding Ws1, the voltage at the negative input terminal of the operational amplifier CMP1 is 0. At this time, if a small voltage disturbance is generated at the positive input terminal of the operational amplifier CMP1, the operational amplifier CMP1 will generate a positive or negative output voltage. Assuming that the output voltage of the operational amplifier CMP1 is in the positive direction at the initial moment, then, under the output voltage in the positive direction, a positive current will be generated, so that the voltage at the negative input terminal of the operational amplifier CMP1 continues to increase until it is greater than or equal to the preset positive threshold, and the polarity of the output terminal of the operational amplifier CMP1 is reversed. Afterwards, the current flowing through the inductor in the first winding Ws1 increases in the reverse direction until it increases to the preset reverse threshold, and the output voltage of the operational amplifier CMP1 is reversed again, thus forming a self-excited oscillation. Among them, the preset forward threshold is a forward voltage threshold set comprehensively based on the first resistor R1 and the second resistor R2, and the preset reverse threshold is a reverse voltage threshold set comprehensively based on the first resistor R1 and the second resistor R2.

[0059] When there is no current to be measured flowing through the magnetic core, the current rise time and current fall time in the above self-excited oscillation process are exactly the same, that is, the duty cycle of the current rise time in the total period is 1 / 2, and the oscillation period is shown in the following formula (1):

[0060] (1)

[0061] Among them, T self is the period of self-excited oscillation, N S is the number of turns of the secondary excitation winding Ws, A E is the cross-sectional area of ​​the core, B S is the saturation magnetic induction intensity, V H is the supply voltage of the operational amplifier.

[0062] When current flows through the magnetic core, a magnetic flux bias is generated in the magnetic core, making it easier for the magnetic core to reach a saturated state in one direction, but more difficult to reach a saturated state in the other direction, resulting in the current rise time and the current fall time being different within a cycle. For the fluxgate sensor in the related art, as shown in FIG4 , FIG4 is a schematic circuit diagram corresponding to the fluxgate sensor in the related art in an embodiment. When the current Ip to be measured flows through, the duty ratio of the corresponding current rise time to the total cycle is shown in the following formula (2). According to the above duty ratio, the current Ip to be measured can be determined.

[0063] (2)

[0064] Where D is the duty cycle of the sensor output voltage waveform, R Sis a detection resistor. For example, the detection resistor may include but is not limited to a first detection resistor and a second detection resistor, etc. Rc is the internal resistance of the winding WS, V EX is the output voltage of the operational amplifier.

[0065] At this time, the current range that can be detected is shown in the following formula (3):

[0066] (3)

[0067] Among them, I M Indicates the peak value of the excitation current, I S Indicates the saturation current of the magnetic core, N S is the number of turns of the secondary excitation winding Ws, N p is the number of turns of the primary excitation winding Ws. It can be seen that the self-excited oscillation period, range and other information of the fluxgate sensor are interrelated, so it is impossible to optimize a single parameter alone in the related technology, which limits the parameter optimization of the fluxgate sensor.

[0068] Based on this, the embodiment of the present application adds a current detection subcircuit. At this time, the current range in the present application becomes as shown in the following formula (4):

[0069] (4)

[0070] Among them, I E is the effective magnetic path length, is the initial magnetic permeability, is the relative magnetic permeability, B S is the saturation magnetic induction intensity.

[0071] It can be seen that after adding a current detection sub-circuit, the current range can be directly changed by only changing the size of the second detection resistor R4 without changing the oscillation period and the number of coil turns. For example, the size of the second detection resistor R4 can be appropriately reduced to increase the measured current range.

[0072] In this embodiment, by adding a current detection sub-circuit, the current range can be directly changed by only changing the size of the second detection resistor R4 without changing the oscillation period and the number of coil turns. In this way, the range of the current measurement circuit corresponding to the fluxgate current sensor can be increased to a certain extent.

[0073] In one embodiment, as shown in FIG5 , the high-frequency compensation circuit 2 includes an inverter 21 and a compensation circuit 22 connected in series, one end of the inverter 21 is connected to one end of the current comparison circuit 1 , and one end of the compensation circuit 22 is grounded; the compensation circuit 22 is connected to the second magnetic core W2;

[0074] The compensation circuit 22 is used to generate a magnetic flux with the same magnitude and opposite direction as that of the current comparison circuit, and eliminate the interference signal in the current to be measured according to the magnetic flux.

[0075] In the embodiment of the present application, the high-frequency compensation circuit 2 includes an inverter 21 and a compensation circuit 22 connected in series, and one end of the inverter 21 is connected to one end of the current comparison circuit 1, for example, the input end of the inverter 21 is connected to the output end of the operational amplifier. The other end of the inverter 21 is connected to the other end of the compensation circuit 22, one end of the compensation circuit 22 is grounded, and the compensation circuit 22 is connected to the second magnetic core W2. In this embodiment, the compensation circuit 22 can generate a magnetic flux that is equal in magnitude and opposite in direction to the current comparison circuit, so that the interference signal in the current to be measured can be eliminated according to the magnetic flux, and the high anti-interference performance of the current measurement circuit can be ensured.

[0076] In one embodiment, the compensation circuit 22 includes a first compensation sub-circuit 221 and a second compensation sub-circuit 222 connected in parallel;

[0077] The first compensation subcircuit 221 and the second compensation subcircuit 222 are used to respectively generate a first magnetic flux that is equal in magnitude and opposite in direction to the first current detection subcircuit, and a second magnetic flux that is equal in magnitude and opposite in direction to the second current detection subcircuit, and eliminate interference signals in the current to be measured based on the first magnetic flux and the second magnetic flux.

[0078] In one embodiment, as shown in FIG. 6 , the first compensation sub-circuit 221 includes a third winding Ws3, a third winding resistor Rc3 and a third detection resistor R5 connected in series, the third winding Ws3 is connected to the second magnetic core W2, one end of the third winding Ws3 is connected to the other end of the inverter 21, and one end of the third detection resistor R5 is grounded.

[0079] In one embodiment, as shown in FIG. 6 , the second compensation sub-circuit 222 includes a fourth winding Ws4, a fourth winding resistor Rc4 and a fourth detection resistor R6 connected in series, the fourth winding Ws4 is connected to the second magnetic core W2, one end of the fourth winding Ws4 is connected to the other end of the inverter 21, and one end of the fourth detection resistor R6 is grounded.

[0080] In one embodiment, the third winding is the same as the first winding, the third winding resistance is the same as the first winding resistance, and the third detection resistor is the same as the first detection resistor; the fourth winding is the same as the second winding, the fourth winding resistance is the same as the second winding resistance, and the fourth detection resistor is the same as the second detection resistor.

[0081] In the embodiment of the present application, the first compensation sub-circuit 221 includes a third winding Ws3, a third winding resistor Rc3 and a third detection resistor R5 connected in series, and the third winding Ws3 is connected to the second magnetic core W2. For example, the third winding Ws3 is wound on the second magnetic core W2, and the winding material, number of turns, and winding method of the third winding Ws3 are exactly the same as those of the first winding Ws1. One end of the third winding Ws3 is connected to the other end of the inverter 21, and the other end of the third winding Ws3 is connected to one end of the third winding resistor Rc3, and the other end of the third winding resistor Rc3 is connected to the other end of the third detection resistor R5, and one end of the third detection resistor R5 is grounded, that is, one end of the third detection resistor R5 is connected to the analog ground. The third winding resistor Rc3 is the same as the first winding resistor Rc1, and the third detection resistor R5 is the same as the first detection resistor R3.

[0082] The second compensation subcircuit 222 includes a fourth winding Ws4, a fourth winding resistor Rc4 and a fourth detection resistor R6 connected in series, the fourth winding Ws4 is connected to the second magnetic core W2, for example, the fourth winding Ws4 is wound on the second magnetic core W2, and the winding material, number of turns, and winding method of the fourth winding Ws4 are exactly the same as those of the second winding Ws2. One end of the fourth winding Ws4 is connected to the other end of the inverter 21, the other end of the fourth winding Ws4 is connected to one end of the fourth winding resistor Rc4, the other end of the fourth winding resistor Rc4 is connected to the other end of the fourth detection resistor R6, and one end of the fourth detection resistor R6 is grounded, that is, one end of the fourth detection resistor R6 is connected to the analog ground. The fourth winding resistor Rc4 is the same as the second winding resistor Rc2, and the fourth detection resistor R6 is the same as the second detection resistor R4.

[0083] The first compensation subcircuit 221 and the second compensation subcircuit 222 can respectively generate a first magnetic flux equal in magnitude and opposite in direction to the first current detection subcircuit, and a second magnetic flux equal in magnitude and opposite in direction to the second current detection subcircuit, and eliminate interference signals in the current to be measured according to the first magnetic flux and the second magnetic flux. The specific working principle is as follows:

[0084] Since the fluxgate sensor may be interfered by the magnetic field, the high-frequency interference signal in the excitation current may be coupled to other windings through the magnetic flux in the main magnetic core, resulting in the presence of high-frequency interference signals in the current, and ultimately leading to the output of erroneous signals. Therefore, the embodiment of the present application designs a high-frequency compensation circuit. When the operational amplifier outputs a high level, the output high-level signal is converted into a negative high level through the inverter, so that the direction of the current flowing through the two compensation sub-circuits is equal to the current flowing through the two current detection sub-circuits, and the direction is opposite. When high-frequency clutter interference appears in the current to be measured, high-frequency clutter interference will be generated in the first winding Ws1 and the second winding Ws2. This interference will also affect the output side of the operational amplifier, so that inverted high-frequency interference will also appear in the high-frequency compensation circuit, that is, high-frequency clutter interference will appear in the third winding WS3 and the fourth winding WS4. At this time, according to Maxwell's fourth equation, the DC current and the high-frequency interference in the winding will generate a time-invariant magnetic flux and a time-varying high-frequency interference magnetic flux in the second magnetic core. Therefore, according to Maxwell's second equation, the time-invariant magnetic flux will no longer induce an electric field in the space of the current to be measured, and the time-varying high-frequency interference magnetic flux will induce a time-varying electric field in the space of the current to be measured. The electric field is a field generated by the high-frequency interference current with the same amplitude and opposite phase as the high-frequency interference in the current to be measured. Therefore, the above two electric fields can offset each other, and the high-frequency interference signal can be eliminated.

[0085] In this embodiment, through the first compensation sub-circuit and the second compensation sub-circuit, a first magnetic flux equal to the first current detection sub-circuit in magnitude and opposite in direction, and a second magnetic flux equal to the second current detection sub-circuit in magnitude and opposite in direction can be generated respectively, thereby generating a compensation current with the same amplitude and opposite phase as the current to be measured, compensating for the high-frequency component in the current, and eliminating the interference signal in the current to be measured, thereby ensuring the accuracy and stability of the fluxgate current sensor.

[0086] In an exemplary embodiment, as shown in FIG. 7 , an exemplary current measurement circuit is provided. The components of the current measurement circuit have been introduced in the above embodiments and will not be described in detail here.

[0087] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0088] The above 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 current measurement circuit, characterized in that: The current measurement circuit comprises a current comparison circuit and a high-frequency compensation circuit, wherein the current comparison circuit and the high-frequency compensation circuit are connected in parallel; the current comparison circuit is connected to the first magnetic core, and the high-frequency compensation circuit is connected to the second magnetic core; The high-frequency compensation circuit is used to eliminate interference signals in the current to be measured to obtain a target current to be measured; the current to be measured is the current directed from the second magnetic core to the first magnetic core; The current comparison circuit is used to detect the target current to be measured.

2. The circuit according to claim 1, characterized in that The current comparison circuit comprises a first current detection subcircuit, a second current detection subcircuit and a comparison subcircuit, wherein the first current detection subcircuit and the second current detection subcircuit are both connected to the first magnetic core; The first current detection subcircuit and the second current detection subcircuit are connected in parallel, the first end of the first current detection subcircuit and the first end of the second current detection subcircuit are both connected to the first end of the comparison subcircuit, and the second end of the first current detection subcircuit, the second end of the second current detection subcircuit, and the second end of the comparison subcircuit are all grounded.

3. The circuit according to claim 2, characterized in that The first current detection subcircuit includes a first winding, a first winding resistor and a first detection resistor connected in series, the first winding is connected to the first magnetic core, one end of the first winding is connected to the first end of the comparison subcircuit, and one end of the first detection resistor is grounded.

4. The circuit according to claim 3, characterized in that The second current detection subcircuit includes a second winding, a second winding resistor and a second detection resistor connected in series, the second winding is connected to the first magnetic core, one end of the second winding is connected to the first end of the comparison subcircuit, and one end of the second detection resistor is grounded.

5. The circuit according to claim 4, characterized in that The comparison subcircuit includes an operational amplifier, a first resistor and a second resistor; The negative input terminal of the operational amplifier is arranged between the first winding resistor and the first detection resistor, the positive input terminal of the operational amplifier is arranged between one end of the first resistor and one end of the second resistor, the output terminal of the operational amplifier is connected to the other end of the second resistor, one end of the first winding, and one end of the second winding, and the other end of the first resistor is grounded; The operational amplifier is used to detect the target current to be measured according to the duty cycle of the output signal.

6. The circuit according to any one of claims 1 to 5, characterized in that: The high-frequency compensation circuit comprises an inverter and a compensation circuit connected in series, one end of the inverter is connected to one end of the current comparison circuit, and one end of the compensation circuit is grounded; the compensation circuit is connected to the second magnetic core; The compensation circuit is used to generate a magnetic flux with the same magnitude and opposite direction as that of the current comparison circuit, and eliminate the interference signal in the current to be measured according to the magnetic flux.

7. The circuit according to claim 6, characterized in that The compensation circuit comprises a first compensation subcircuit and a second compensation subcircuit connected in parallel; The first compensation subcircuit and the second compensation subcircuit are used to respectively generate a first magnetic flux that is equal in magnitude and opposite in direction to the first current detection subcircuit, and a second magnetic flux that is equal in magnitude and opposite in direction to the second current detection subcircuit, and eliminate interference signals in the current to be measured based on the first magnetic flux and the second magnetic flux.

8. The circuit according to claim 7, characterized in that The first compensation subcircuit includes a third winding, a third winding resistor and a third detection resistor connected in series, the third winding is connected to the second magnetic core, one end of the third winding is connected to the other end of the inverter, and one end of the third detection resistor is grounded.

9. The circuit according to claim 8, characterized in that The second compensation subcircuit includes a fourth winding, a fourth winding resistor and a fourth detection resistor connected in series, the fourth winding is connected to the second magnetic core, one end of the fourth winding is connected to the other end of the inverter, and one end of the fourth detection resistor is grounded.

10. The circuit according to claim 9, characterized in that The third winding is the same as the first winding, the third winding resistance is the same as the first winding resistance, and the third detection resistance is the same as the first detection resistance; the fourth winding is the same as the second winding, the fourth winding resistance is the same as the second winding resistance, and the fourth detection resistance is the same as the second detection resistance.

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