Current sampling circuit and sampling device

Abstract

The current sampling circuit comprises a voltage input unit, an operational amplification unit and a bias giving unit, the operational amplification unit comprises a first operational amplification circuit and a second operational amplification circuit, the input end of the first operational amplification circuit is connected with the voltage input unit, and the output end of the second operational amplification circuit is connected with the bias giving unit. The output end of the first operational amplifier circuit is connected with the input end of the second operational amplifier circuit, and the output end of the second operational amplifier circuit serves as the signal output end of the current sampling circuit. The bias giving unit is connected with the second operational amplifier circuit. Specifically, the current sampling circuit provided by the utility model is small in device number and simple in circuit structure, and can achieve the functions of adjustable bias voltage, adjustable positive and negative half-cycle transformation ratios and turnover of the absolute value of a specific position signal, thereby being capable of improving the sampling precision.

Description

Technical Field

[0001] This application relates to the field of circuit technology, and in particular to a current sampling circuit and sampling device. Background Technology

[0002] Bidirectional current sensing is a technique used to measure the direction and amplitude of current flow, and it is widely used in power management, battery charging and discharging monitoring, motor control, and other fields. It can accurately detect both forward and reverse current flow and provide corresponding signals for subsequent processing or control systems.

[0003] However, existing bidirectional current sampling circuits are complex in structure and have low sampling accuracy. Utility Model Content

[0004] To address the aforementioned problems, this application provides a current sampling circuit and sampling device, which can solve the problems of complex structure and low sampling accuracy of bidirectional current sampling circuits.

[0005] To address the aforementioned problems, the first technical solution provided in this application is: to provide a current sampling circuit, comprising:

[0006] Voltage input unit;

[0007] The operational amplifier unit includes a first operational amplifier circuit and a second operational amplifier circuit. The input terminal of the first operational amplifier circuit is connected to the voltage input unit, and the output terminal of the first operational amplifier circuit is connected to the input terminal of the second operational amplifier circuit. The output terminal of the second operational amplifier circuit serves as the signal output terminal of the current sampling circuit.

[0008] The biasing unit is connected to the second operational amplifier circuit.

[0009] In one embodiment, the voltage input unit includes an AC voltage source, a DC voltage source, and a bias voltage source;

[0010] The AC voltage source and the DC voltage source are connected in series between the inverting input terminal of the first operational amplifier circuit and ground potential; the bias voltage source is connected in series between the non-inverting input terminal of the first operational amplifier circuit and ground potential.

[0011] In one embodiment, the first operational amplifier circuit includes:

[0012] A first operational amplifier, comprising a non-inverting input terminal, an inverting input terminal, and an output terminal;

[0013] A first resistor, the first end of which is connected to the AC voltage source, and the second end of which is connected to the inverting input terminal of the first operational amplifier;

[0014] The second resistor has its first end connected to the inverting input terminal of the first operational amplifier and its second end connected to the output terminal of the first operational amplifier.

[0015] The non-inverting input of the first operational amplifier is connected to the bias voltage source.

[0016] In one embodiment, the first operational amplifier circuit further includes a first diode connected in series between the second resistor and the non-inverting input terminal of the first operational amplifier;

[0017] In this configuration, the anode of the first diode is connected to the second terminal of the second resistor, and the cathode of the first diode is connected to the non-inverting input terminal of the first operational amplifier.

[0018] In one embodiment, the second operational amplifier circuit includes:

[0019] The second operational amplifier includes a non-inverting input terminal, an inverting input terminal, and an output terminal.

[0020] The third resistor has its first end connected to the second end of the second resistor, and its second end connected to the inverting input of the second operational amplifier.

[0021] The fourth resistor has its first end connected to the inverting input terminal of the first operational amplifier and its second end connected to the output terminal of the second operational amplifier; and the output terminal of the second operational amplifier serves as the signal output terminal of the current sampling circuit.

[0022] The fifth resistor has its first end connected to the inverting input of the first operational amplifier and its second end connected to the non-inverting input of the second operational amplifier.

[0023] In one embodiment, the second operational amplifier circuit further includes a second diode connected in series between the output terminal of the first operational amplifier and the non-inverting input terminal of the second operational amplifier;

[0024] The anode of the second diode is connected to the output terminal of the first operational amplifier, and the cathode of the second diode is connected to the non-inverting input terminal of the second operational amplifier.

[0025] In one embodiment, the biasing unit includes a reference voltage source and a sixth resistor;

[0026] The first end of the sixth resistor is connected to the inverting input of the second operational amplifier, and the first end of the sixth resistor is connected to the reference voltage source.

[0027] In one embodiment, the second resistor, the third resistor, and the fourth resistor have the same resistance value.

[0028] In one embodiment, the DC voltage source and the bias voltage source have the same voltage.

[0029] To address the aforementioned problems, the second technical solution provided in this application is: to provide a sampling device, comprising:

[0030] A current sampling circuit, wherein the current sampling circuit includes any one of the current sampling circuits described in the above description;

[0031] The sampling unit is connected to the signal output terminal of the current sampling circuit.

[0032] The beneficial effect of this application is that, unlike the prior art, the current sampling circuit and sampling device provided in this application include a voltage input unit, an operational amplifier unit, and a biasing unit. The operational amplifier unit includes a first operational amplifier circuit and a second operational amplifier circuit. The input terminal of the first operational amplifier circuit is connected to the voltage input unit, and the output terminal of the first operational amplifier circuit is connected to the input terminal of the second operational amplifier circuit. The output terminal of the second operational amplifier circuit serves as the signal output terminal of the current sampling circuit. The biasing unit is connected to the second operational amplifier circuit. Specifically, the current sampling circuit provided in this application has fewer components, a simpler circuit structure, and can achieve adjustable bias voltage, adjustable positive and negative half-cycle ratios, and signal absolute value inversion at specific positions, thereby improving sampling accuracy. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0034] Figure 1 A schematic diagram of a current sampling circuit provided in one embodiment of this application;

[0035] Figure 2 A circuit diagram of a current sampling circuit provided in an embodiment of this application;

[0036] Figure 3 The input and output waveforms of a current sampling circuit provided in an embodiment of this application are shown.

[0037] Figure 4 Input and output waveform diagram of a current sampling circuit provided in another embodiment of this application;

[0038] Figure 5 Input and output waveform diagram of a current sampling circuit provided in another embodiment of this application;

[0039] Figure 6 This is a schematic diagram of a sampling device provided in one embodiment of this application.

[0040] Label Explanation:

[0041] Current sampling circuit -100;

[0042] Voltage input unit -10; AC voltage source -VIN; DC voltage source -VDC1; Bias voltage source -VDC3;

[0043] Operational amplifier unit-20; First operational amplifier circuit-21; First operational amplifier-OP1; First resistor-R1; Second resistor-R2; First diode-D1; Second operational amplifier circuit-22; Second operational amplifier-OP2; Third resistor-R3; Fourth resistor-R4; Fifth resistor-R5; Second diode-D2;

[0044] Bias supply unit -30; Reference voltage source -VDC2; Sixth resistor -R6;

[0045] Sampling device-1000; Sampling unit-200. Detailed Implementation

[0046] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0047] The terms "first," "second," and "third" in this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movements between components in a specific orientation (as shown in the figures). If the specific orientation changes, the directional indications also change accordingly. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0048] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0049] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0050] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0051] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0052] See Figure 1 and Figure 2 , Figure 1 A schematic diagram of a current sampling circuit provided in one embodiment of this application; Figure 2 This is a circuit diagram of a current sampling circuit provided in one embodiment of this application.

[0053] This application provides a current sampling circuit 100, including a voltage input unit 10, an operational amplifier unit 20, and a bias supply unit 30.

[0054] The voltage input unit 10 can input various types of signals, such as periodic signals like sine wave signals, square wave signals, and triangular wave signals, or random pulse signals or other non-periodic complex signals.

[0055] Combination Figure 1 and Figure 2 In one embodiment, the voltage input unit 10 includes an AC voltage source VIN, a DC voltage source VDC1, and a bias voltage source VDC3. The AC voltage source VIN and the DC voltage source VDC1 are connected in series between the inverting input terminal of the first operational amplifier circuit 21 of the operational amplifier unit 20 and ground potential; the bias voltage source VDC3 is connected in series between the non-inverting input terminal of the first operational amplifier circuit 21 and ground potential.

[0056] Specifically, the AC voltage source VIN outputs a time-varying periodic signal with characteristics such as amplitude, frequency, and phase. The DC voltage source VDC1 provides a DC bias voltage, a fixed DC voltage that serves as a reference level for the input signal, determining its average potential. The bias voltage source VDC3 provides the input bias voltage; it is an additional DC voltage source VDC1 used to further adjust the input signal level to meet the specific requirements of the sampling circuit, such as better matching the input signal to the dynamic range of the sampling circuit or ensuring the signal is within the optimal operating region of certain components in the circuit.

[0057] In some embodiments, the voltages of DC voltage source VDC1 and bias voltage source VDC3 may be the same or different. When the voltages of DC voltage source VDC1 and bias voltage source VDC3 are the same, the DC operating point analysis and debugging process of the circuit can be simplified.

[0058] The operational amplifier unit 20 includes a first operational amplifier circuit 21 and a second operational amplifier circuit 22. The input terminal of the first operational amplifier circuit 21 is connected to the voltage input unit 10, and the output terminal of the first operational amplifier circuit 21 is connected to the input terminal of the second operational amplifier circuit 22. The output terminal of the second operational amplifier circuit 22 serves as the signal output terminal of the current sampling circuit 100. The biasing unit 30 is connected to the second operational amplifier circuit 22.

[0059] Specifically, the first operational amplifier circuit 21 amplifies the signal input from the voltage input unit 10 to amplify it to a suitable amplitude for processing by the second operational amplifier circuit 22. Furthermore, the first operational amplifier circuit 21 also acts as a buffer, isolating the voltage input unit 10 from the second operational amplifier circuit 22, reducing the influence of the subsequent circuit on the preceding signal source, and ensuring the stability and accuracy of the input signal.

[0060] The second operational amplifier circuit 22 amplifies the signal output by the first operational amplifier circuit 21 again to meet the requirements of the sampling circuit for signal amplitude.

[0061] The second operational amplifier circuit 22 also works in conjunction with the bias supply unit 30 to receive the bias signal provided by the bias supply unit 30. This bias signal can further adjust the operating point of the second operational amplifier circuit 22 to ensure that the circuit can work normally under different input signal conditions, thereby improving the stability and reliability of the circuit.

[0062] The signal output terminal of the second operational amplifier circuit 22 outputs the signal processed by the two-stage operational amplifier circuit. This signal will be sent to the sampling unit, such as a microcontroller or MCU (microcontroller unit), for further processing, and finally realize the sampling and digitization of the input voltage signal.

[0063] Specifically, the current sampling circuit 100 provided in this application has a small number of components, a simple circuit structure, and can improve sampling accuracy.

[0064] Combination Figure 1 and Figure 2 In one embodiment, the first operational amplifier circuit 21 includes a first operational amplifier OP1, a first resistor R1, and a second resistor R2.

[0065] Among them, the first operational amplifier OP1 is the core amplification element in the first operational amplifier circuit 21, including a non-inverting input terminal, an inverting input terminal, and an output terminal. It amplifies the signal according to the input signal and the feedback network.

[0066] The function of the first resistor R1 is to introduce the signal from the AC voltage source VIN to the inverting input of the operational amplifier, enabling the operational amplifier to process the signal. Specifically, the first terminal of the first resistor R1 is connected to the AC voltage source VIN, and the second terminal of the first resistor R1 is connected to the inverting input of the first operational amplifier OP1.

[0067] The first end of the second resistor R2 is connected to the inverting input of the first operational amplifier OP1, and the second end of the second resistor R2 is connected to the output of the first operational amplifier OP1, thus forming a negative feedback network. Negative feedback can stabilize the amplification factor of the operational amplifier and improve the linearity and stability of the circuit.

[0068] The non-inverting input terminal of the first operational amplifier OP1 is connected to the bias voltage source VDC3 to provide a DC bias for the first operational amplifier OP1, thereby determining the operating point of the first operational amplifier OP1 and ensuring that it operates in the appropriate operating region.

[0069] Combination Figure 1 and Figure 2 In one embodiment, the second operational amplifier circuit 22 includes a second operational amplifier OP2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5.

[0070] The second operational amplifier OP2, as the core amplification element in the second operational amplifier circuit 22, is used to further amplify and process the preceding signal. Specifically, the second operational amplifier OP2 includes a non-inverting input terminal, an inverting input terminal, and an output terminal, and the output terminal of the second operational amplifier OP2 serves as the signal output terminal of the current sampling circuit 100.

[0071] The first end of the third resistor R3 is connected to the second end of the second resistor R2, and the second end of the third resistor R3 is connected to the inverting input of the second operational amplifier OP2, which serves to transmit the preamplifier signal and adjust the input signal magnitude.

[0072] The first end of the fourth resistor R4 is connected to the inverting input of the first operational amplifier OP1, and the second end of the fourth resistor R4 is connected to the output of the second operational amplifier OP2; thus forming the negative feedback network of the second operational amplifier circuit 22, which can adjust the amplification factor of the second operational amplifier OP2 and stabilize its operation.

[0073] The first end of the fifth resistor R5 is connected to the inverting input of the first operational amplifier OP1, and the second end of the fifth resistor R5 is connected to the non-inverting input of the second operational amplifier OP2, thus playing a certain role in signal coupling and level adjustment.

[0074] In some embodiments, the resistance values ​​of the second resistor R2, the third resistor R3, and the fourth resistor R4 can be the same or different. When the resistance values ​​of the second resistor R2, the third resistor R3, and the fourth resistor R4 are the same, the calculation and analysis of the amplification factor of the two-stage operational amplifier circuit can be simplified to some extent.

[0075] Combination Figure 1 and Figure 2 Furthermore, the first operational amplifier circuit 21 also includes a first diode D1 connected in series between the second resistor R2 and the non-inverting input terminal of the first operational amplifier OP1; wherein the anode of the first diode D1 is connected to the second terminal of the second resistor R2, and the cathode of the first diode D1 is connected to the non-inverting input terminal of the first operational amplifier OP1.

[0076] The function of the first diode D1 in the first operational amplifier circuit 21 is as follows:

[0077] 1. Forward conduction characteristic: When the output voltage of the first operational amplifier OP1 is higher than the voltage at its non-inverting input terminal plus the forward conduction voltage of the first diode D1, the first diode D1 conducts, which limits the voltage at the non-inverting input terminal of the first operational amplifier OP1 to about the output voltage minus the forward conduction voltage of the first diode D1. This acts as a limiting function, preventing the voltage at the non-inverting input terminal from being too high, avoiding the first operational amplifier OP1 from entering the saturation region, and protecting the first operational amplifier OP1 and subsequent circuits.

[0078] 2. Signal clamping: Under certain circumstances, the first diode D1 can clamp the signal at the non-inverting input of the first operational amplifier OP1 within a specific level range, so that the output of the first operational amplifier OP1 will not change too much due to large fluctuations in the input signal, thus ensuring the stability of the output signal.

[0079] 3. Dynamic range adjustment: The first diode D1 can dynamically adjust the input signal range of the first operational amplifier OP1 according to the voltage signal in the circuit, so that the circuit can maintain a relatively stable working state under different input signal amplitudes.

[0080] Combination Figure 1 and Figure 2 Furthermore, the second operational amplifier circuit 22 also includes a second diode D2 connected in series between the output terminal of the first operational amplifier OP1 and the non-inverting input terminal of the second operational amplifier OP2; wherein the anode of the second diode D2 is connected to the output terminal of the first operational amplifier OP1, and the cathode of the second diode D2 is connected to the non-inverting input terminal of the second operational amplifier OP2.

[0081] The function of the second diode D2 in the second operational amplifier circuit 22 is as follows:

[0082] 1. Signal Level Adjustment: The second diode D2 can adjust the signal input to the non-inverting input terminal of the second operational amplifier OP2. When the output signal of the first operational amplifier OP1 exceeds a certain voltage, the second diode D2 conducts, which limits the voltage at the non-inverting input terminal of the second operational amplifier OP2 to a relatively stable level, thereby affecting the output signal of the second operational amplifier OP2.

[0083] Preventing signal overshoot: The second diode D2 can prevent the input signal of the second operational amplifier OP2 from becoming too large due to the overshoot of the output signal of the first operational amplifier OP1, thus avoiding the second operational amplifier OP2 from entering the nonlinear operating region and ensuring the quality of the output signal of the second operational amplifier OP2.

[0084] Signal transmission and isolation: The second diode D2 can isolate some abnormal parts of the output signal of the first operational amplifier OP1 to a certain extent, so that the signal entering the non-inverting input terminal of the second operational amplifier OP2 is more in line with the design requirements, thereby improving the reliability and stability of the circuit.

[0085] Specifically, the limiting and clamping effects of the first diode D1 and the second diode D2 prevent the operational amplifier from being damaged by excessively large input signals, while ensuring stable operation of the circuit under large signal fluctuations and avoiding circuit failures caused by signal overshoot. Furthermore, the first diode D1 and the second diode D2 can adjust the level of the input signal, ensuring that the input and output signals of the two-stage operational amplifier are within a suitable range to meet the requirements of subsequent circuits.

[0086] In one embodiment, the biasing unit 30 includes a reference voltage source VDC2 and a sixth resistor R6; wherein, the first end of the sixth resistor R6 is connected to the inverting input of the second operational amplifier OP2, and the first end of the sixth resistor R6 is connected to the reference voltage source VDC2.

[0087] Specifically, the biasing unit 30, by introducing a reference voltage source VDC2, can precisely adjust the operating point of the second operational amplifier OP2, ensuring that the output signal of the second operational amplifier OP2 has the required DC level to meet the DC level requirements of the subsequent current sampling circuit 100. For different input signals and subsequent circuit requirements, the bias of the second operational amplifier OP2 can be adjusted by changing the output voltage of the reference voltage source VDC2 and the resistance value of the sixth resistor R6, giving the entire circuit better adaptability and flexibility.

[0088] The following is an application example of the current sampling circuit 100 provided in this application:

[0089] Let \(R2 = R3 = R4\); decompose the gain of the current sampling circuit into \(VDC1>VIN\) and \(VDC1<VIN\); let \(R5=\alpha*R2\); \(R6 = \beta*R2\); \(VDC1 = VDC3\).

[0090] If \(VIN>0\); the relationship between the output voltage and the input voltage is as follows:

[0091]

[0092] Output DC bias \(U1\), whose value is

[0093] Turn ratio \(Kup\), whose value is

[0094] IF \(VIN<0\); the relationship between the output voltage and the input voltage is as follows:

[0095]

[0096] Where \(V2\) is the voltage value after superimposing \(VDC1\) and \(VIN\).

[0097] Output DC bias \(U2\), whose value is

[0098] Turn ratio \(Kdown\), whose value is

[0099] Combined with Figure 3 , Figure 3 is the input-output waveform diagram of the current sampling circuit provided by an embodiment of the present application. As Figure 3 shown, the input side \(VIN\) is a sine wave with a peak-to-peak value of 2.2V, and \(VDC1\) is a 2V bias voltage. The output side is a bias voltage not equal to 2V superimposed with the absolute value of \(VIN\) multiplied by different turn ratios in the positive and negative half-cycles.

[0100] Combined with Figure 4 , Figure 4 is the input-output waveform diagram of the current sampling circuit provided by another embodiment of the present application. As Figure 4 shown, the input side \(VIN\) is a sine wave with a peak-to-peak value of 2.2V, and \(VDC1\) is a 2V bias voltage. The output side is a bias voltage not equal to 2V superimposed with the absolute value of \(VIN\) multiplied by the same turn ratio in the positive and negative half-cycles.

[0101] Combined with Figure 5 , Figure 5 is the input-output waveform diagram of the current sampling circuit provided by yet another embodiment of the present application. As Figure 5As shown, VDC2 is set to a bias voltage that is not equal to the input side VIN. The input side VIN is a sine wave with a peak-to-peak value of 2.2V, and VDC1 is a 2V bias voltage. The output side is a bias voltage that is not equal to 2V, superimposed on the VDC2 voltage point as a reference. The absolute value is then multiplied by the same (which can be different by adjustment) turns ratio in both the positive and negative half-cycles.

[0102] Specifically, the current sampling circuit 100 provided in this application is constructed using common discrete components, with a small number of components, a simple circuit structure, and is combined with... Figures 3-5 As shown, the current sampling circuit 100 can achieve adjustable bias voltage, adjustable positive and negative half-cycle ratios, and signal absolute value inversion at specific positions, thereby improving sampling accuracy.

[0103] See Figure 6 , Figure 6 This is a schematic diagram of a sampling device provided in one embodiment of this application.

[0104] This application also provides a sampling device 1000, which includes a current sampling circuit 100 and a sampling unit 200 provided in any of the above embodiments. The sampling unit 200 is connected to the signal output terminal of the current sampling circuit 100 and is used to further process the signal output by the current sampling circuit 100. The sampling unit 200 includes, but is not limited to, a microcontroller, an MCU (microcontroller unit), etc.

[0105] The sampling device 1000 can be applied to fields such as power management, battery charging and discharging monitoring, and motor control.

[0106] The above are merely embodiments of this application and do not limit the scope of this patent application. Any equivalent structural or procedural changes made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A current sampling circuit, characterized by, include: Voltage input unit; The operational amplifier unit includes a first operational amplifier circuit and a second operational amplifier circuit. The input terminal of the first operational amplifier circuit is connected to the voltage input unit, and the output terminal of the first operational amplifier circuit is connected to the input terminal of the second operational amplifier circuit. The output terminal of the second operational amplifier circuit serves as the signal output terminal of the current sampling circuit. The biasing unit is connected to the second operational amplifier circuit.

2. The current sampling circuit of claim 1, wherein, The voltage input unit includes an AC voltage source, a DC voltage source, and a bias voltage source; The AC voltage source and the DC voltage source are connected in series between the inverting input terminal of the first operational amplifier circuit and ground potential; the bias voltage source is connected in series between the non-inverting input terminal of the first operational amplifier circuit and ground potential.

3. The current sampling circuit of claim 2, wherein, The first operational amplifier circuit includes: A first operational amplifier, comprising a non-inverting input terminal, an inverting input terminal, and an output terminal; A first resistor, the first end of which is connected to the AC voltage source, and the second end of which is connected to the inverting input terminal of the first operational amplifier; The second resistor has its first end connected to the inverting input terminal of the first operational amplifier and its second end connected to the output terminal of the first operational amplifier. The non-inverting input of the first operational amplifier is connected to the bias voltage source.

4. The current sampling circuit of claim 3, wherein, The first operational amplifier circuit further includes a first diode connected in series between the second resistor and the non-inverting input terminal of the first operational amplifier; In this configuration, the anode of the first diode is connected to the second terminal of the second resistor, and the cathode of the first diode is connected to the non-inverting input terminal of the first operational amplifier.

5. The current sampling circuit of claim 3, wherein, The second operational amplifier circuit includes: The second operational amplifier includes a non-inverting input terminal, an inverting input terminal, and an output terminal. The third resistor has its first end connected to the second end of the second resistor, and its second end connected to the inverting input of the second operational amplifier. The fourth resistor has its first end connected to the inverting input terminal of the first operational amplifier and its second end connected to the output terminal of the second operational amplifier; and the output terminal of the second operational amplifier serves as the signal output terminal of the current sampling circuit. The fifth resistor has its first end connected to the inverting input of the first operational amplifier and its second end connected to the non-inverting input of the second operational amplifier.

6. The current sampling circuit of claim 5, wherein, The second operational amplifier circuit further includes a second diode connected in series between the output terminal of the first operational amplifier and the non-inverting input terminal of the second operational amplifier; The anode of the second diode is connected to the output terminal of the first operational amplifier, and the cathode of the second diode is connected to the non-inverting input terminal of the second operational amplifier.

7. The current sampling circuit of claim 5, wherein, The bias supply unit includes a reference voltage source and a sixth resistor; The first end of the sixth resistor is connected to the inverting input of the second operational amplifier, and the first end of the sixth resistor is connected to the reference voltage source.

8. The current sampling circuit of claim 7, wherein, The second resistor, the third resistor, and the fourth resistor have the same resistance value.

9. The current sampling circuit of claim 2, wherein, The DC voltage source and the bias voltage source have the same voltage.

10. A sampling device, characterized by include: A current sampling circuit, wherein the current sampling circuit comprises the current sampling circuit according to any one of claims 1-9; The sampling unit is connected to the signal output terminal of the current sampling circuit.

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