Micro-current detection sensor circuit

Abstract

The invention, which belongs to the technical field of the sensor, discloses a micro-current detection sensor circuit comprising a coil L1 through which a device to be detected passes; the short circuit prevention resistor R1 is connected with the coil L1 in series; the FB modulation circuit is connected to the two ends of the coil L1 and the short circuit prevention resistor R1 in series, and the FB modulation circuit is used for modulating a current signal of a to-be-tested device to the coil L1; and the signal processing circuit is connected between the coil L1 and the short circuit prevention resistor R1 and is used for detecting a voltage value corresponding to the current flowing into the coil L1 and outputting the voltage value so as to determine the current flowing into the coil L1 according to the voltage value. According to the circuit, the double operational amplifier circuits are adopted for detecting and outputting the voltage, output voltage data are not affected by a power supply VDD, error correction can be conducted on the detected voltage, the anti-interference capacity is improved, and the fault-tolerant rate, the stability and the reliability are high.

Description

Technical Field

[0001] The invention belongs to the technical field of sensors, and in particular relates to a micro-current detection sensor circuit. Background Art

[0002] Current and residual current detection technologies can be divided into two categories: contact and non-contact. Among them, non-contact detection technology indirectly detects the current size by detecting the magnetic field generated by the current. In non-contact detection technology, current detection based on magnetic modulation technology generally applies excitation to a magnetic material to cause its magnetization degree to oscillate. The magnetic field generated by the measured magnetic field or the measured current will cause an offset to the oscillation of its magnetization degree. The magnitude of the measured magnetic field or the measured current is obtained by measuring this offset value. The advantage of current detection based on magnetic modulation technology is that it can measure any waveform, including direct current. However, its circuit is particularly complex. At present, most products of this technology require hundreds of electronic components to realize their functions, with high manufacturing costs and low overall circuit reliability. Summary of the invention

[0003] In order to solve the above technical problems, an embodiment of the present application provides a micro-current detection sensor circuit.

[0004] According to one aspect of an embodiment of the present application, a microcurrent detection sensor circuit is provided, which includes: a coil L1, through which a device under test passes; an anti-short-circuit resistor R1, which is connected in series with the coil L1; an FB modulation circuit, which is connected in series between the coil L1 and the anti-short-circuit resistor R1, and is used to modulate a current signal of the device under test onto the coil L1; a signal processing circuit, which is connected between the coil L1 and the anti-short-circuit resistor R1, and is used to detect and output a voltage value corresponding to the current flowing into the coil L1, so as to determine the current flowing into the coil L1 based on the voltage value.

[0005] In one embodiment of the present application, the FB modulation circuit includes a first modulation circuit and a second modulation circuit.

[0006] In one embodiment of the present application, the first modulation circuit includes a switch tube Q1 and a switch tube Q3, the switch tube Q1 and the switch tube Q3 are connected in series, the source of the switch tube Q1 is connected to the anti-short-circuit resistor R1, the drain of Q1 is connected to the drain of the switch tube Q3, and the source of the switch tube Q3 is connected to the coil L1.

[0007] In one embodiment of the present application, the base of the switch tube Q1 and the base of the switch tube Q3 are both connected to the controller, and the drain of Q1 and the drain of the switch tube Q3 are both connected to the power supply VDD.

[0008] In one embodiment of the present application, the second modulation circuit includes a switch tube Q2 and a switch tube Q4, the switch tube Q2 and the switch tube Q4 are connected in series, the drain of the switch tube Q2 is connected to the anti-short-circuit resistor R1, the source of Q2 is connected to the source of the switch tube Q4, and the drain of the switch tube Q4 is connected to the coil L1.

[0009] In one embodiment of the present application, the base of the switch tube Q2 and the base of the switch tube Q4 are both connected to the controller, and the source of Q2 and the source of the switch tube Q4 are both grounded.

[0010] In one embodiment of the present application, the signal processing circuit includes a first operational amplifier circuit and a second operational amplifier circuit connected in parallel.

[0011] In one embodiment of the present application, the first operational amplifier circuit includes a first operational amplifier U1, a resistor, and a capacitor, and a non-inverting input terminal of the first operational amplifier U1 is connected to a power supply VDD.

[0012] In one embodiment of the present application, the second operational amplifier circuit includes a second operational amplifier U2, a resistor, and a capacitor, and the non-inverting input terminal of the second operational amplifier U2 is grounded.

[0013] In one embodiment of the present application, the voltage value Vo1 output by the first operational amplifier circuit is the same as the voltage value Vo2 output by the second operational amplifier circuit.

[0014] In the technical solution provided in the embodiment of the present application, the above-mentioned micro-current detection sensor circuit modulates the current signal of the device to be tested to the coil L1 through the FB modulation circuit, and then detects the voltage value corresponding to the current flowing into the coil L1 through the signal processing circuit and outputs it, so as to determine the current flowing into the coil L1 according to the voltage value. The current detection circuit of the present application only requires a small number of components to achieve stable and accurate detection of tiny currents, and the cost is greatly reduced; in addition, the current detection circuit of the present application uses a dual operational amplifier circuit to detect and output voltage, and the output voltage data is not affected by the power supply VDD. At the same time, there are two equal outputs. If there is an obvious error in the output result, the detected voltage can be corrected, which improves the anti-interference ability of the detection circuit of the present application, and has high fault tolerance, high stability, and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0016] Figure 1 is a structural schematic diagram of a micro-current detection sensor circuit shown in an exemplary embodiment of the present application;

[0017] Figure 2 is a structural schematic diagram of a micro-current detection sensor circuit shown in another exemplary embodiment of the present application;

[0018] Figure 3 is a schematic diagram of an equivalent circuit structure in a modulation state shown in an exemplary embodiment of the present application;

[0019] Figure 4 is a schematic diagram of an equivalent circuit structure in another modulation state shown in an exemplary embodiment of the present application;

[0020] Figure 5 It is a schematic diagram of the on / off state of the switch tubes Q1 to Q4 in the micro-current detection sensor circuit shown in another exemplary embodiment of the present application.

[0021] Figure Number:

[0022] 20-FB modulation circuit;

[0023] 21- a first modulation circuit;

[0024] 22- a second modulation circuit;

[0025] 10-Signal processing circuit. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, rather than all the embodiments. The components of the embodiment of the present invention described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiment of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but only represents the selected embodiment of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of the embodiments of the present invention, it should be noted that the terms "upper", "inside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the invented product is usually placed when in use, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In the description of the present invention, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] The present application conducts an in-depth study on the problems of complex circuits, high costs, and low circuit reliability in the technology of detecting tiny currents through magnetic modulation in non-contact current detection in the related art, and provides a micro-current detection sensor circuit with a relatively simple circuit, a relatively small number of electronic components required, and a low manufacturing cost, while being able to ensure stable and reliable current detection results.

[0028] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0029] Please refer to Figure 1 , Figure 1 It is a schematic diagram of the structure of a micro-current detection sensor circuit shown in an exemplary embodiment of the present application.

[0030] like Figure 1As shown, the micro-current detection sensor circuit includes a coil L1, through which the device under test passes; an anti-short-circuit resistor R1, which is connected in series with the coil L1; an FB modulation circuit 20, which is connected in series between the coil L1 and the anti-short-circuit resistor R1, and is used to modulate the current signal of the device under test onto the coil L1; a signal processing circuit 10, which is connected between the coil L1 and the anti-short-circuit resistor R1, and is used to detect the voltage value corresponding to the current flowing into the coil L1 and output it, so as to determine the current flowing into the coil L1 according to the voltage value.

[0031] It should be noted that in the embodiment of the present application, the coil L1 is a magnetic conductor device / magnetic device that is closed at both ends, and the coil shape of the coil L1 can be circular, flat, square, triangular, etc., and the present application is not limited to this.

[0032] In one embodiment of the present application, the FB modulation circuit 20 includes a first modulation circuit 21 and a second modulation circuit 22. The first modulation circuit 21 and the second modulation circuit 22 are both connected in parallel at both ends of the series circuit of the anti-short-circuit resistor R1 and the coil L1, and are used to modulate the current signal of the device under test to the coil L1.

[0033] It should be noted that the first modulation circuit 21 includes at least two switching tubes.

[0034] In an exemplary embodiment, the first modulation circuit 21 includes a switch tube Q1 and a switch tube Q3, the switch tube Q1 and the switch tube Q3 are connected in series, the source of the switch tube Q1 is connected to the short-circuit protection resistor R1, the drain of Q1 is connected to the drain of the switch tube Q3, and the source of the switch tube Q3 is connected to the coil L1. The base of the switch tube Q1 and the base of the switch tube Q3 are both connected to the controller, and the controller is used to control the switch tube Q1 and the switch tube Q3 to be turned on and off. The drain of Q1 and the drain of the switch tube Q3 are both connected to the power supply VDD.

[0035] It should be noted that the second modulation circuit 22 includes at least two switching tubes.

[0036] In an exemplary embodiment, the second modulation circuit 22 includes a switch tube Q2 and a switch tube Q4, the switch tube Q2 and the switch tube Q4 are connected in series, the drain of the switch tube Q2 is connected to the short-circuit protection resistor R1, the source of Q2 is connected to the source of the switch tube Q4, and the drain of the switch tube Q4 is connected to the coil L1. The base of the switch tube Q2 and the base of the switch tube Q4 are both connected to the controller, and the controller is used to control the switching on and off of the switch tube Q2 and the switch tube Q4. The source of Q2 and the source of the switch tube Q4 are both grounded.

[0037] In one embodiment of the present application, the signal processing circuit 10 includes a first operational amplifier circuit and a second operational amplifier circuit connected in parallel.

[0038] It should be noted that the current detection circuit of the present application uses a dual op amp circuit to detect and output voltage. The output voltage data is not affected by the power supply VDD. At the same time, there are two equal outputs. If there is an obvious error in the output result, the detected voltage can be corrected, which improves the anti-interference ability of the detection circuit of the present application, and has high fault tolerance, high stability and high reliability.

[0039] In one embodiment of the present application, the first operational amplifier circuit includes a first operational amplifier U1, a resistor, and a capacitor, and a non-inverting input terminal of the first operational amplifier U1 is connected to a power supply VDD.

[0040] In an exemplary embodiment, the first operational amplifier circuit includes a first operational amplifier U1, a resistor R5, a resistor R6, a resistor R7, and a capacitor C1, and the connection method thereof is as follows: the non-inverting input terminal of the first operational amplifier U1 is connected in series with the resistor R7 and then connected to the power supply VDD; one end of the resistor R5 is connected to the reverse input terminal of the first operational amplifier U1, and the other end is connected between the anti-short-circuit resistor R1 and the coil L1; one end of the resistor R6 is connected to the reverse input terminal of the first operational amplifier U1, and the other end is connected to the output terminal of the first operational amplifier U1; one end of the capacitor C1 is connected to the reverse input terminal of the first operational amplifier U1, and the other end is connected to the output terminal of the first operational amplifier U1, and is in parallel with R6.

[0041] In one embodiment of the present application, the second operational amplifier circuit includes a second operational amplifier U2, a resistor, and a capacitor, and the non-inverting input terminal of the second operational amplifier U2 is grounded.

[0042] In an exemplary embodiment, the second operational amplifier circuit includes a second operational amplifier U2, a resistor R2, a resistor R3, a resistor R4, and a capacitor C2, and the connection method thereof is as follows: the same-direction input terminal of the second operational amplifier U2 is connected in series with the resistor R4 and then grounded; one end of the resistor R2 is connected to the reverse input terminal of the second operational amplifier U2, and the other end is connected between the anti-short-circuit resistor R1 and the coil L1; one end of the resistor R3 is connected to the reverse input terminal of the second operational amplifier U2, and the other end is connected to the output terminal of the second operational amplifier U2; one end of the capacitor C2 is connected to the reverse input terminal of the second operational amplifier U2, and the other end is connected to the output terminal of the second operational amplifier U2, and is in parallel with R3.

[0043] It should be noted that, in the embodiment of the present application, the voltage value Vo1 output by the first operational amplifier circuit is the same as the voltage value Vo2 output by the second operational amplifier circuit. Principle: The FB modulation circuit 20 can realize two modulation states when working, and can switch between the two working states by controlling the switch tube Q1, the switch tube Q2, the switch tube Q3, and the switch tube Q4 to be turned off or on by the controller.

[0044] Modulation state 1: When the switch tubes Q1 and Q4 are turned on and the switch tubes Q2 and Q3 are turned off, the equivalent circuit of the micro-current detection sensor circuit in the embodiment of the present application can be found in Figure 3 In this modulation state, the voltage value Vo1 output by the first op amp circuit is the same as the voltage value Vo2 output by the second op amp circuit. The voltage value Vo1 output by the first op amp circuit is calculated as: VO1 = K*(I_L+DI)*R1; the voltage value Vo2 output by the second op amp circuit is calculated as: VO2 = K*(VDD-(I_L+DI)*R1).

[0045] Modulation state 2: When the switch tubes Q1 and Q4 are turned off and the switch tubes Q2 and Q3 are turned on, the equivalent circuit of the micro-current detection sensor circuit in the embodiment of the present application can be found in Figure 4 In this modulation state, the voltage value Vo1 output by the first op amp circuit and the voltage value Vo2 output by the second op amp circuit are also the same. The voltage value Vo1 output by the first op amp circuit is calculated as VO1 = K*(VDD-(-I_L+DI)*R1); the voltage value Vo2 output by the second op amp circuit is calculated as VO2B = K*(-I_L+DI)*R1.

[0046] Therefore, in the two modulation states of the micro-current detection sensor circuit of the embodiment of the present application, the voltage value Vo1 output by the first op amp circuit and the voltage value Vo2 output by the second op amp circuit are always the same. Using the dual op amp circuit detection circuit of the embodiment of the present application, the output voltage has nothing to do with the power supply VDD and is not affected by the power supply. At the same time, there are two equal voltage outputs Vo1=Vo2, which is convenient for correcting the detected voltage when there is an error such as an obvious inequality in the output result, with high fault tolerance and good stability, further increasing the reliability of the detection circuit.

[0047] Figure 5 FIG. 1 is a schematic diagram of the on / off state of the switch tubes Q1 to Q4 in the micro-current detection sensor circuit shown in another exemplary embodiment of the present application. When the circuit is in the working state, the principle of turning off or on the switch tubes Q1, Q2, Q3, and Q4 is as follows: Figure 5 That is, in the FB modulation circuit, the states of the two switches at the diagonal positions must be consistent, such as Figure 2 As shown in the figure, the switch tubes Q1 and Q4 should be turned on or off at the same time, and the switch tubes Q2 and Q3 should be turned on or off at the same time. The states of the switch tubes in the upper and lower positions should remain opposite, such as Figure 2 As shown, when the switch tube Q1 is turned on, the switch tube Q2 should be in the off state, and when the switch tube Q3 is turned on, the switch tube Q4 should be in the off state.

[0048] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A micro-current detection sensor circuit, characterized in that: include: A coil L1, through which the device under test passes; An anti-short-circuit resistor R1, wherein the anti-short-circuit resistor R1 is connected in series with the coil L1; An FB modulation circuit, wherein the FB modulation circuit is connected in series between the coil L1 and the anti-short circuit resistor R1, and the FB modulation circuit is used to modulate the current signal of the device under test onto the coil L1; A signal processing circuit is connected between the coil L1 and the anti-short-circuit resistor R1, and is used to detect and output a voltage value corresponding to the current flowing into the coil L1, so as to determine the current flowing into the coil L1 according to the voltage value.

2. The micro-current detection sensor circuit according to claim 1, characterized in that: The FB modulation circuit includes a first modulation circuit and a second modulation circuit.

3. The micro-current detection sensor circuit according to claim 2, characterized in that: The first modulation circuit includes a switch tube Q1 and a switch tube Q3, the switch tube Q1 and the switch tube Q3 are connected in series, the source of the switch tube Q1 is connected to the anti-short-circuit resistor R1, the drain of Q1 is connected to the drain of the switch tube Q3, and the source of the switch tube Q3 is connected to the coil L1.

4. The micro-current detection sensor circuit according to claim 3, characterized in that: The base of the switch tube Q1 and the base of the switch tube Q3 are both connected to the controller, and the drain of Q1 and the drain of the switch tube Q3 are both connected to the power supply VDD.

5. The micro-current detection sensor circuit according to claim 2, characterized in that: The second modulation circuit includes a switch tube Q2 and a switch tube Q4, the switch tube Q2 and the switch tube Q4 are connected in series, the drain of the switch tube Q2 is connected to the anti-short-circuit resistor R1, the source of Q2 is connected to the source of the switch tube Q4, and the drain of the switch tube Q4 is connected to the coil L1.

6. The micro-current detection sensor circuit according to claim 5, characterized in that: The base of the switch tube Q2 and the base of the switch tube Q4 are both connected to the controller, and the source of Q2 and the source of the switch tube Q4 are both grounded.

7. The micro-current detection sensor circuit according to claim 1, characterized in that: The signal processing circuit includes a first operational amplifier circuit and a second operational amplifier circuit connected in parallel.

8. The micro-current detection sensor circuit according to claim 7, characterized in that: The first operational amplifier circuit includes a first operational amplifier U1, a resistor, and a capacitor. The non-inverting input terminal of the first operational amplifier U1 is connected to a power supply VDD.

9. The micro-current detection sensor circuit according to claim 7, characterized in that: The second operational amplifier circuit includes a second operational amplifier U2, a resistor, and a capacitor. The non-inverting input terminal of the second operational amplifier U2 is grounded.

10. The micro-current detection sensor circuit according to any one of claims 7 to 9, characterized in that: The voltage value Vo1 output by the first operational amplifier circuit is the same as the voltage value Vo2 output by the second operational amplifier circuit.

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