Current measurement circuit

Abstract

The application relates to a current measurement circuit. The current measurement circuit comprises a current comparison circuit and a high-frequency compensation circuit, the current comparison circuit and the high-frequency compensation circuit being connected in parallel; the current comparison circuit is connected with a first magnetic core, and the high-frequency compensation circuit is connected with a second magnetic core; the high-frequency compensation circuit is used for eliminating interference signals in a to-be-measured current to obtain a target to-be-measured current; the to-be-measured current is a current of the second magnetic core pointing to the first magnetic core; and the current comparison circuit is used for detecting the target to-be-measured current. The high-frequency compensation circuit in the embodiment of the application can eliminate high-frequency interference signals in the to-be-measured current, and the current comparison circuit can detect the target to-be-measured current from which the high-frequency interference signals are eliminated, so that the current measurement circuit in the embodiment of the application can be used to accurately measure the current of the second magnetic core pointing to the first magnetic core.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit, in particular to a current measurement circuit. BACKGROUND

[0002] With the development of circuit technology, the demand for current measurement is increasing, and current measurement technology can be widely used in feedback control, leakage current monitoring, electrical and electronic systems at present, based on which various types of current sensors are produced, for example, a fluxgate current sensor, which is a sensor designed and manufactured based on the principle of fluxgate effect. The 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 has the problem of low measurement accuracy. SUMMARY

[0004] Therefore, it is necessary to provide a current measurement circuit capable of improving current measurement accuracy in view of the above technical problems.

[0005] In a first aspect, the present application provides a current measurement circuit, which comprises 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 with a first magnetic core, and the high-frequency compensation circuit is connected with a second magnetic core;

[0006] The high-frequency compensation circuit is used for eliminating interference signals in the to-be-measured current to obtain a target to-be-measured current; the to-be-measured current is the current of the second magnetic core pointing to the first magnetic core.

[0007] The current comparison circuit is used for detecting the target to-be-measured current.

[0008] In one embodiment, the current comparison circuit comprises a first current detection sub-circuit, a second current detection sub-circuit and a comparison sub-circuit, and the first current detection sub-circuit and the second current detection sub-circuit are connected with the first magnetic core.

[0009] The first current detection sub-circuit and the second current detection sub-circuit are connected in parallel, the first end of the first current detection sub-circuit and the first end of the second current detection sub-circuit are connected with the first end of the comparison sub-circuit, and the second end of the first current detection sub-circuit, the second end of the second current detection sub-circuit and the second end of the comparison sub-circuit are grounded.

[0010] In one of the embodiments, the first current detection sub-circuit comprises a first winding, a first winding resistor and a first detection resistor connected in series, the first winding is connected with the first magnetic core, one end of the first winding is connected with the first end of the comparison sub-circuit, and one end of the first detection resistor is grounded.

[0011] In one of the embodiments, the second current detection sub-circuit comprises a second winding, a second winding resistor and a second detection resistor connected in series, the second winding is connected with the first magnetic core, one end of the second winding is connected with the first end of the comparison sub-circuit, and one end of the second detection resistor is grounded.

[0012] In one of the embodiments, the comparison sub-circuit comprises an operational amplifier, a first resistor and a second resistor.

[0013] The negative input end of the operational amplifier is arranged between the first winding resistor and the first detection resistor, the positive input end of the operational amplifier is arranged between one end of the first resistor and one end of the second resistor, the output end of the operational amplifier is connected with 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 configured to detect the target current to be measured according to the duty cycle of the output signal.

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

[0016] The compensation circuit is configured to generate a magnetic flux equal in size and opposite in direction to 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 comprises a first compensation sub-circuit and a second compensation sub-circuit connected in parallel.

[0018] The first compensation sub-circuit and the second compensation sub-circuit are configured to generate a first magnetic flux equal in size and opposite in direction to the first current detection sub-circuit, and a second magnetic flux equal in size and opposite in direction to the second current detection sub-circuit, respectively, and eliminate the interference signal in the current to be measured according to the first magnetic flux and the second magnetic flux.

[0019] In one of the embodiments, the first compensation sub-circuit comprises a third winding, a third winding resistor and a third detection resistor connected in series, the third winding is connected with the second magnetic core, one end of the third winding is connected with the other end of the inverter, and one end of the third detection resistor is grounded.

[0020] In one of the embodiments, the second compensation sub-circuit comprises a fourth winding, a fourth winding resistor and a fourth detection resistor connected in series, the fourth winding is connected with the second magnetic core, one end of the fourth winding is connected with the other end of the inverter, and one end of the fourth detection resistor is grounded.

[0021] In one of the embodiments, the third winding is the same as the first winding, the third winding resistor is the same as the first winding resistor, 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 resistor is the same as the second winding resistor, and the fourth detection resistor is the same as the second detection resistor.

[0022] The current measurement circuit comprises 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 with the first magnetic core, and the high-frequency compensation circuit is connected with the second magnetic core; the high-frequency compensation circuit is used for eliminating the interference signal in the to-be-measured current to obtain a target to-be-measured current; the to-be-measured current is the current of the second magnetic core pointing to the first magnetic core; the current comparison circuit is used for detecting the target to-be-measured current. The high-frequency compensation circuit in the embodiment of the present application can eliminate the high-frequency interference signal in the to-be-measured current, and the current comparison circuit can detect the target to-be-measured current in which the high-frequency interference signal is eliminated, so that the current measurement circuit in the embodiment of the present application can be used to accurately measure the current of the second magnetic core pointing to the first magnetic core. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the drawings needed to be used in the description of the embodiments of the present application or the related art will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other related drawings can be obtained by those skilled in the art without any creative effort.

[0024] Figure 1 It is a structural schematic diagram of the current measurement circuit in one embodiment;

[0025] Figure 2 It is a structural schematic diagram of the current measurement circuit comprising the current comparison circuit in one embodiment;

[0026] Figure 3A circuit schematic diagram of the current comparison circuit in one embodiment;

[0027] Figure 4 A circuit schematic diagram corresponding to the magnetic flux gate sensor in the related art in one embodiment;

[0028] Figure 5 A structural schematic diagram of the current measurement circuit including the high frequency compensation circuit in one embodiment;

[0029] Figure 6 A circuit schematic diagram of the high frequency compensation circuit in one embodiment;

[0030] Figure 7 A circuit schematic diagram of the current measurement circuit in another embodiment.

[0031] BRIEF DESCRIPTION OF DRAWINGS

[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 sub-circuit: 11; Second current detection sub-circuit: 12; Comparison sub-circuit: 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 sub-circuit: 221; Second compensation sub-circuit: 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 scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not intended to limit the present application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application; the terms "include" and "have" and any variations thereof used herein are intended to cover a non-exclusive inclusion.

[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 "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0036] Reference herein to "embodiments" means that a particular feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of the application. The occurrence of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor does it necessarily refer to a separate or alternative embodiment. It is expressly understood that the embodiments described herein can be combined with other embodiments.

[0037] With the development of circuit technology, the demand for current measurement is increasing, and the form of current to be detected is also 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 developed, for example, a fluxgate current sensor. The fluxgate current sensor is a sensor designed and manufactured based on the principle of fluxgate effect. The fluxgate effect refers to the phenomenon that the resistivity of a magnetic material changes under the action of an external magnetic field. Therefore, the fluxgate sensor can measure the current in the circuit by detecting the change in resistivity.

[0038] However, the traditional self-excited fluxgate current sensor is an RL multivibrator composed of a nonlinear mutual inductor and an operational amplifier to measure the current. The range of the traditional self-excited fluxgate current sensor is only 0.5 A. 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 can be disturbed by the magnetic field. High-frequency interference signals in the excitation current can be coupled into other windings, resulting in high-frequency interference signals in the measured current, ultimately leading to inaccurate output signals, thereby affecting the accuracy and stability of the fluxgate sensor. Therefore, the current measurement circuit based on the fluxgate current sensor has the problem of low measurement accuracy.

[0039] Based on this, the embodiments of the present application provide a current measurement circuit.

[0040] In one embodiment, as shown in Figure 1 A current measurement circuit is provided, which includes a current comparison circuit 1 and a high-frequency compensation circuit 2 connected in parallel; the current comparison circuit 1 is connected with a first magnetic core W1, and the high-frequency compensation circuit 2 is connected with a second magnetic core W2;

[0041] The high-frequency compensation circuit 2 is configured to eliminate the interference signal in the to-be-measured current Ip to obtain a target to-be-measured current; the to-be-measured current Ip is a current in which the second magnetic core W2 points to the first magnetic core W1.

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

[0043] In the embodiment, the current measurement circuit includes the current comparison circuit 1 and the 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 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 with the first magnetic core W1, and the high-frequency compensation circuit 2 is connected with the second magnetic core W2. In this way, the to-be-measured current Ip is generated between the first magnetic core W1 and the second magnetic core W2, and the direction of the to-be-measured current Ip is the direction in which the second magnetic core W2 points to the first magnetic core W1. Since there is a magnetic field interference around the current measurement circuit, the to-be-measured current Ip has a high-frequency interference signal. Based on this, the high-frequency compensation circuit 2 can eliminate the high-frequency interference signal in the to-be-measured current Ip, and the current comparison circuit 1 can detect the target to-be-measured current in which the high-frequency interference signal is eliminated.

[0044] In the current measurement circuit, the current measurement circuit includes the current comparison circuit and the high-frequency compensation circuit, 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, and the high-frequency compensation circuit is connected with the second magnetic core; the high-frequency compensation circuit is configured to eliminate the interference signal in the to-be-measured current to obtain a target to-be-measured current; the to-be-measured current is a current in which the second magnetic core points to the first magnetic core; and the current comparison circuit is configured to detect the target to-be-measured current. The high-frequency compensation circuit in the embodiment can eliminate the high-frequency interference signal in the to-be-measured current, and the current comparison circuit can detect the target to-be-measured current in which the high-frequency interference signal is eliminated. In this way, the current measurement circuit in the embodiment can be used to accurately measure the current in which the second magnetic core points to the first magnetic core.

[0045] In one embodiment, as shown in Figure 2 The current comparison circuit 1 includes the first current detection sub-circuit 11, the second current detection sub-circuit 12, and the comparison sub-circuit 13; the first current detection sub-circuit 11 and the second current detection sub-circuit 12 are connected with the first magnetic core W1.

[0046] The first current detection sub-circuit 11 and the second current detection sub-circuit 12 are connected in parallel; the first end of the first current detection sub-circuit 11 and the first end of the second current detection sub-circuit 12 are connected with the first end of the comparison sub-circuit 13; and the second end of the first current detection sub-circuit 11, the second end of the second current detection sub-circuit 12, and the second end of the comparison sub-circuit 13 are grounded.

[0047] In the embodiment, the current comparison circuit 1 comprises a first current detection sub-circuit 11, a second current detection sub-circuit 12 and a comparison sub-circuit 13. The first current detection sub-circuit 11 and the second current detection sub-circuit 12 are connected with the first magnetic core W1. The first current detection sub-circuit 11 and the second current detection sub-circuit 12 are connected in parallel. The first end of the first current detection sub-circuit 11 and the first end of the second current detection sub-circuit 12 are connected with the first end of the comparison sub-circuit 13. The second end of the first current detection sub-circuit 11, the second end of the second current detection sub-circuit 12 and the second end of the comparison sub-circuit 13 are grounded. Optionally, the circuit structure of the first current detection sub-circuit 11 and the second current detection sub-circuit 12 can be the same or different, which is not limited in the embodiment.

[0048] In one of the embodiments, as shown in Figure 3 The first current detection sub-circuit 11 comprises a first winding Ws1, a first winding resistor Rc1 and a first detection resistor R3 connected in series. The first winding Ws1 is connected with the first magnetic core W1. One end of the first winding Ws1 is connected with the first end of the comparison sub-circuit 13. One end of the first detection resistor R3 is grounded.

[0049] In one of the embodiments, as shown in Figure 3 The second current detection sub-circuit 12 comprises a second winding Ws2, a second winding resistor Rc2 and a second detection resistor R4 connected in series. The second winding Ws2 is connected with the first magnetic core W1. One end of the second winding Ws2 is connected with the first end of the comparison sub-circuit 13. One end of the second detection resistor R4 is grounded.

[0050] In one of the embodiments, as shown in Figure 3 The comparison sub-circuit 13 comprises an operational amplifier CMP1, a first resistor R1 and a second resistor R2.

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

[0052] The operational amplifier CMP1 is used for detecting the target current to be measured according to the duty cycle of the output signal V EX1 .

[0053] Wherein, the first winding resistance Rc1 is the coil self-resistance of the first winding, the second winding resistance Rc2 is the coil self-resistance 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 application, the first current detection sub-circuit 11 includes the first winding Ws1, the first winding resistance Rc1 and the first detection resistance R3 connected in series, the first winding Ws1 is connected with 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 with the output end of the operational amplifier CMP1 in the comparison sub-circuit 13, the other end of the first winding Ws1 is connected with one end of the first winding resistance Rc1, the other end of the first winding resistance Rc1 is connected with the other end of the first detection resistance R3, and one end of the first detection resistance R3 is grounded.

[0055] The second current detection sub-circuit 12 includes the second winding Ws2, the second winding resistance Rc2 and the second detection resistance R4 connected in series, the second winding Ws2 is connected with 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 with the output end of the operational amplifier CMP1 in the comparison sub-circuit 13, the other end of the second winding Ws2 is connected with one end of the second winding resistance Rc2, the other end of the second winding resistance Rc2 is connected with the other end of the second detection resistance R4, and one end of the second detection resistance R4 is grounded.

[0056] The comparison sub-circuit 13 includes the operational amplifier CMP1, the first resistance R1 and the second resistance R2, wherein the negative input end of the operational amplifier CMP1 is arranged between the other end of the first winding resistance Rc1 and the other end of the first detection resistance R3, the positive input end of the operational amplifier CMP1 is arranged between one end of the first resistance R1 and one end of the second resistance R2, the output end of the operational amplifier CMP1 is connected with the other end of the second resistance R2, one end of the first winding Ws1 and one end of the second winding Ws2, and the other end of the first resistance R1 is grounded, that is, the other end of the first resistance R1 is connected with the analog ground.

[0057] In the embodiment of the application, the target current to be detected can be detected by the operational amplifier CMP1 in the current comparison circuit according to the duty cycle of the output signal V EX1 , and 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 occurs 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, under the positive direction output voltage, a positive current is generated, so that the voltage at the negative input terminal of the operational amplifier CMP1 continuously rises until it is greater than or equal to the preset positive threshold, the polarity of the output terminal of the operational amplifier CMP1 is reversed. After that, the current flowing through the inductor in the first winding Ws1 reverses and increases until it increases to the preset reverse threshold, the output voltage of the operational amplifier CMP1 is reversed again, thus forming self-oscillation. The preset positive threshold is a positive voltage threshold set according to the first resistor R1 and the second resistor R2, and the preset reverse threshold is a reverse voltage threshold set according to the first resistor R1 and the second resistor R2.

[0059] When no current flows through the magnetic core, the current rise time and the current fall time in the above self-oscillation process are completely the same, that is, the duty ratio of the current rise time in the total period is 1 / 2, and the oscillation period is as shown in the following formula (1):

[0060] (1)

[0061] Where, T self is the period of self-oscillation, N S is the number of turns of the excitation secondary winding Ws, A E is the cross-sectional area of the magnetic core, B S is the saturation magnetic induction, 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, which makes the magnetic core more easily reach the saturation state in one direction, and makes the magnetic core more difficult to reach the saturation state in the other direction, resulting in that the current rise time and the current fall time are not the same in a period. For the magnetic flux gate sensor in the related art, as shown in Figure 4 , the circuit schematic diagram corresponding to the magnetic flux gate sensor in the related art in an embodiment is as shown in Figure 4 , when the current to be measured Ip flows, the duty ratio of the corresponding current rise time in the total period is as shown in the following formula (2), according to the above duty ratio, the current to be measured Ip can be determined.

[0063] (2)

[0064] Where, D is the duty ratio of the sensor output voltage waveform, R STo detect the resistance, for example, the detection resistance can include but is not limited to the first detection resistance and the second detection resistance, etc., Rc is the internal resistance of the winding WS, V EX For the output voltage of the operational amplifier.

[0065] At this time, the detectable current range is shown in the following formula (3):

[0066] (3)

[0067] Wherein, I M represents the peak value of the excitation current, I S represents the saturation current of the magnetic core, N S is the number of turns of the excitation secondary winding Ws, N p is the number of turns of the excitation primary winding Ws. It can be known that the self-oscillation period, range and other information of the fluxgate sensor are related to each other, so a single parameter in the related technology cannot be optimized alone, which limits the parameter optimization of the fluxgate sensor.

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

[0069] (4)

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

[0071] It can be known that after adding a current detection subcircuit, the size of the current range can be directly changed without changing the oscillation period and the number of turns of the coil, for example, the size of the second detection resistance R4 can be appropriately reduced, so that the measured current range becomes larger.

[0072] In the embodiment, by adding a current detection subcircuit, the size of the current range can be directly changed without changing the oscillation period and the number of turns of the coil, for example, the size of the second detection resistance R4 can be directly changed, so that 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 Figure 5 shown, 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 with the second magnetic core W2;

[0074] The compensation circuit 22 is configured to generate magnetic fluxes with the same size and opposite direction as the current comparison circuit, and eliminate the interference signals in the to-be-measured current according to the magnetic fluxes.

[0075] In the embodiment, the high-frequency compensation circuit 2 includes the inverter 21 and the compensation circuit 22 connected in series. 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 the embodiment, the compensation circuit 22 can generate magnetic fluxes with the same size and opposite direction as the current comparison circuit, so that the interference signals in the to-be-measured current can be eliminated according to the magnetic fluxes, and the high anti-interference performance of the current measurement circuit can be ensured.

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

[0077] The first compensation sub-circuit 221 and the second compensation sub-circuit 222 are configured to generate first magnetic fluxes with the same size and opposite direction as the first current detection sub-circuit, and second magnetic fluxes with the same size and opposite direction as the second current detection sub-circuit, respectively, and eliminate the interference signals in the to-be-measured current according to the first magnetic fluxes and the second magnetic fluxes.

[0078] In one embodiment, as shown in Figure 6 the first compensation sub-circuit 221 includes the third winding Ws3, the third winding resistor Rc3 and the 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. One end of the third detection resistor R5 is grounded.

[0079] In one embodiment, as shown in Figure 6 the second compensation sub-circuit 222 includes the fourth winding Ws4, the fourth winding resistor Rc4 and the 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. 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 resistor is the same as the first winding resistor, 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 resistor is the same as the second winding resistor, and the fourth detection resistor is the same as the second detection resistor.

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

[0082] The second compensation sub-circuit 222 comprises a fourth winding Ws4, a fourth winding resistor Rc4 and a fourth detection resistor R6 connected in series, the fourth winding Ws4 is connected with the second magnetic core W2, for example, the fourth winding Ws4 is wound on the second magnetic core W2, and the winding material, the number of turns and the winding mode of the fourth winding Ws4 are completely same as those of the second winding Ws2. One end of the fourth winding Ws4 is connected with the other end of the inverter 21, the other end of the fourth winding Ws4 is connected with one end of the fourth winding resistor Rc4, the other end of the fourth winding resistor Rc4 is connected with 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 with the analog ground. The fourth winding resistor Rc4 is same as the second winding resistor Rc2, and the fourth detection resistor R6 is same as the second detection resistor R4.

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

[0084] Since the magnetic flux gate sensor can be interfered by the magnetic field, the high frequency interference signal in the excitation current can be coupled to other windings through the magnetic flux in the main magnetic core, resulting in the existence of high frequency interference signal in the current, and finally resulting in the output of wrong signal, therefore, the embodiment of the application designs a high frequency compensation circuit, when the output of the operational amplifier is high level, the output high level signal becomes negative high level through the inverter, so that the current direction flowing through the two compensation sub-circuits is equal in size and opposite in direction to the current flowing through the two current detection sub-circuits. When the high frequency noise interference appears in the to-be-measured current, the high frequency noise interference will be generated in the first winding Ws1 and the second winding Ws2, which will also affect the output side of the operational amplifier, so that the high frequency interference in the high frequency compensation circuit will also appear, that is, the high frequency noise interference will appear in the third winding WS3 and the fourth winding WS4. At this time, according to Maxwell's fourth equation, the direct 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, so that according to Maxwell's second equation, the time-invariant magnetic flux will not induce an electric field in the space of the to-be-measured current, and the time-varying high frequency interference magnetic flux will induce a time-varying electric field in the space of the to-be-measured current, which is a field with the same amplitude and opposite phase as the high frequency interference in the to-be-measured current. Therefore, the above two electric fields can offset each other, that is, the high frequency interference signal can be eliminated.

[0085] In the embodiment, through the first compensation sub-circuit and the second compensation sub-circuit, the first magnetic flux equal in size and opposite in direction to the first current detection sub-circuit and the second magnetic flux equal in size and opposite in direction to the second current detection sub-circuit can be generated respectively, so that the compensation current equal in amplitude and opposite in phase to the to-be-measured current can be generated, the high frequency component in the current can be compensated, and the interference signal in the to-be-measured current can be eliminated, thereby ensuring the accuracy and stability of the magnetic flux gate current sensor.

[0086] In one exemplary embodiment, as shown in Figure 7 each component of the current measurement circuit is introduced in the above embodiment and will not be described here.

[0087] Each technical feature of the above embodiments can be combined arbitrarily, and in order to make the description concise, not all possible combinations of each technical feature in the above embodiments are described, however, as long as the combination of these technical features does not exist contradictory, it should be considered as the range recited in the application.

[0088] The above embodiments only express several implementation ways of the present application, and the description is specific and detailed, but it should not be understood as a limitation to the patent scope of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A current measuring circuit, characterized in that, The current measurement circuit includes a current comparison circuit and a high-frequency compensation circuit, which 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 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 current comparison circuit includes a first current detection sub-circuit, a second current detection sub-circuit, and a comparison sub-circuit, wherein both the first current detection sub-circuit and the second current detection sub-circuit are connected to the first magnetic core. The first current detection subcircuit and the second current detection subcircuit are connected in parallel. The first terminal of the first current detection subcircuit and the first terminal of the second current detection subcircuit are both connected to the first terminal of the comparator subcircuit. The second terminals of the first current detection subcircuit, the second current detection subcircuit, and the comparator subcircuit are all grounded.

2. The circuit according to claim 1, characterized in that, The first current detection sub-circuit 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 sub-circuit, and one end of the first detection resistor is grounded.

3. The circuit according to claim 2, characterized in that, The second current detection sub-circuit 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 sub-circuit, and one end of the second detection resistor is grounded.

4. The circuit according to claim 3, characterized in that, The comparator circuit includes an operational amplifier, a first resistor, and a second resistor; The negative input terminal of the operational amplifier is located between the first winding resistor and the first detection resistor, the positive input terminal of the operational amplifier is located 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 based on the duty cycle of the output signal.

5. The circuit according to any one of claims 1-4, characterized in that, 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. The compensation circuit is used to generate a magnetic flux that is equal in magnitude and opposite in direction to that of the current comparison circuit, and to eliminate interference signals in the current to be measured based on the magnetic flux.

6. The circuit according to claim 5, characterized in that, The compensation circuit includes a first compensation sub-circuit and a second compensation sub-circuit connected in parallel. The first compensation sub-circuit and the second compensation sub-circuit are respectively used to generate a first magnetic flux that is equal in magnitude and opposite in direction to the first current detection sub-circuit, and a second magnetic flux that is equal in magnitude and opposite in direction to the second current detection sub-circuit, and to eliminate interference signals in the current to be measured based on the first magnetic flux and the second magnetic flux.

7. The circuit according to claim 6, characterized in that, The first compensation sub-circuit 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.

8. The circuit according to claim 7, characterized in that, The second compensation sub-circuit 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.

9. The circuit according to claim 8, characterized in that, The third winding is the same as the first winding, the resistance of the third winding is the same as the resistance of the first winding, and the third detection resistor is the same as the first detection resistor; the fourth winding is the same as the second winding, the resistance of the fourth winding is the same as the resistance of the second winding, and the fourth detection resistor is the same as the second detection resistor.

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