A voltage and current sampling conversion device

Abstract

The utility model discloses a voltage and current sampling and conversion device, in which: the current / voltage conversion circuit converts the collected AC current signal into a voltage signal and transmits it to the precision amplifier circuit for amplification processing; the precision rectifier circuit with voltage bias receives the AC voltage transmitted by the precision amplifier circuit and performs rectification processing to output a DC voltage signal to the low-pass filter circuit for filtering processing; the debiasing circuit receives the voltage signal output by the low-pass filter circuit for processing, and directly outputs the voltage signal after passing through the current and voltage output selection circuit or converts it into a current signal through the voltage / current conversion circuit for output. The utility model can effectively ensure the lossless transmission of the signal, and after filtering, the signal is converted into a standard signal through the debiasing circuit, so that the accuracy of the system can be guaranteed to the maximum extent.

Description

Technical Field

[0001] The utility model belongs to the technical field of signal conversion circuits, and particularly relates to a voltage and current sampling conversion device. Background Art

[0002] With the rapid development of automation technology, all walks of life have paid much attention to the acquisition and conversion of electrical signals such as current and voltage. In particular, the demand for high-precision conversion of current and voltage signals is getting higher and higher. Wide-range and high-precision conversion of signals has always been a relatively difficult problem.

[0003] In order to solve this problem, a voltage and current sampling conversion device is now designed. Utility Model Content

[0004] The purpose of the utility model is to provide a voltage and current sampling conversion device, which can effectively ensure the lossless transmission of signals, and convert the signals into standard signals through a debiasing circuit after filtering, so as to maximize the accuracy of the system.

[0005] In order to solve the above technical problems, the utility model is realized by the following technical solutions:

[0006] The utility model discloses a voltage and current sampling and conversion device, comprising a current / voltage conversion circuit, wherein the current / voltage conversion circuit converts a collected alternating current signal into a voltage signal and transmits the converted signal to a precision amplifier circuit for amplification processing; a precision rectifier circuit with a voltage bias, wherein the precision rectifier circuit with a voltage bias receives the alternating voltage transmitted by the precision amplifier circuit, performs rectification processing, and outputs a direct current voltage signal to a low-pass filter circuit for filtering processing; and a debiasing circuit, wherein the debiasing circuit receives the voltage signal output by the low-pass filter circuit for processing, and directly outputs the voltage signal after passing through a current and voltage output selection circuit, or converts the voltage signal into a current signal through a voltage / current conversion circuit for output.

[0007] As a preferred technical solution of the utility model, the current / voltage conversion circuit includes a resistor RS, and the resistor RS is connected to the current to be measured to convert the current signal into a voltage signal and then transmit it to the precision amplifier circuit.

[0008] As a preferred technical solution of the utility model, the precision amplifier circuit is used to amplify the received voltage signal, including operational amplifiers U1, U2, U3 and U4; the non-inverting input terminal of the operational amplifier U1 is connected to one end of the resistor RS, and the non-inverting input terminal of the operational amplifier U2 is connected to the other end of the resistor RS; the inverting input terminal of the operational amplifier U1 is connected in series with resistor R1 to the inverting input terminal of the operational amplifier U2; the inverting input terminal of the operational amplifier U1 is connected in series with resistor R2 to the operational amplifier U1; the inverting input terminal of the operational amplifier U2 is connected in series with resistor R201 to the output terminal; the output terminal of the operational amplifier U1 is connected in series with resistor R30 is connected to the inverting input terminal of the operational amplifier U3, the output terminal of the operational amplifier U2 is connected in series with a resistor R31 to the non-inverting input terminal of the operational amplifier U3, and the resistor R31 is also connected in series with a resistor R41 to ground; the input terminal of the operational amplifier U3 is connected in series with a resistor R40 to the output terminal; the output terminal of the operational amplifier U3 is connected in series with a resistor R5 to the non-inverting input terminal of the operational amplifier U4, and a grounding capacitor C1 is also connected between the resistor R5 and the non-inverting input terminal of the operational amplifier U4; the inverting input terminal of the operational amplifier U4 is connected to the output terminal, and the output terminal of the operational amplifier U4 outputs the amplified voltage signal u1 to a precision rectifier circuit with voltage bias.

[0009] As a preferred technical solution of the utility model, the precision rectifier circuit with voltage bias is used to rectify the received alternating current and output direct current, including an operational amplifier U5 and a resistor R8; the inverting input terminal of the operational amplifier U5 is connected in series with resistors R7 and R6 in sequence to the output terminal of the operational amplifier U4 to receive the voltage signal u1, and the non-inverting input terminal of the operational amplifier U5 is grounded; the output terminal of the operational amplifier U5 is connected in series with a diode D2 to a low-pass filter circuit, and the inverting input terminal of the operational amplifier U5 is connected in series with a diode D1 to the output terminal; one end of the resistor R8 is connected to the middle connection point of the resistors R7 and R6, and the other end of the resistor R8 is connected to the cathode of the diode D2.

[0010] As a preferred technical solution of the utility model, the low-pass filter circuit is used to filter the rectified DC power, and the low-pass filter circuit includes operational amplifiers U6 and U7; the in-phase input terminal of the operational amplifier U6 is connected in series with resistors R10 and R9 to the cathode of the diode D2; the inverting input terminal of the operational amplifier U6 is connected in series with resistor R11 to the output terminal; a grounding capacitor C2 is connected between the in-phase input terminal of the operational amplifier U6 and the resistor R10; the intermediate connection point of the resistors R10 and R9 is connected in series with a capacitor C 3 to the output terminal of the operational amplifier U6; the output terminal of the operational amplifier U6 is connected in series with a resistor R12 to the non-inverting input terminal of the operational amplifier U7; a grounding capacitor C4 is connected between the non-inverting input terminal of the operational amplifier U7 and the resistor R12; a series resistor R13 is connected to the ground at the inverting input terminal of the operational amplifier U7, and the output terminal of the operational amplifier U7 outputs the filtered voltage signal u2 to the de-biasing circuit; a series resistor R14 is connected from the inverting input terminal of the operational amplifier U7 to the output terminal, and both ends of the resistor R14 are connected in parallel with the capacitor C5.

[0011] As a preferred technical solution of the utility model, the de-biasing circuit is used to remove the bias voltage in the signal, including operational amplifiers U8, U9 and resistor R21; the operational amplifier U8 is connected in series with resistor R15 to a reference voltage source Uref; the resistor R15 is also connected in series with resistor R16 to ground, and the inverting input terminal of the operational amplifier U8 is connected to the output terminal; the output terminal of the operational amplifier U8 is connected in series with resistor R17 to the non-inverting input terminal of the operational amplifier U9, and the non-inverting input terminal of the operational amplifier U9 is also connected in series with resistor R18 to the output terminal of the operational amplifier U7 to receive the voltage signal u2; the inverting input terminal of the operational amplifier U9 is connected in series with resistor R20 to ground, and the inverting input terminal of the operational amplifier U9 is also connected in series with capacitor C6 to the output terminal; the output terminal of the operational amplifier U9 is connected in series with resistor R19 to the current and voltage output selection circuit; one end of the resistor R21 is connected to the inverting input terminal of the operational amplifier U9, and the other end of the resistor R21 is connected to the middle connection point between resistor R19 and the current and voltage output selection circuit.

[0012] As a preferred technical solution of the utility model, the current and voltage output selection circuit is used to select the output signal type of the circuit, including resistors R22 and R23; the first ends of the resistors R22 and R23 are both connected to the resistor R19, and the second end of the resistor R22 outputs the voltage signal uo as a direct output; the second end of the resistor R23 outputs the voltage signal u3 to the voltage / current conversion circuit for conversion.

[0013] As a preferred technical solution of the utility model, the voltage / current conversion circuit is used to convert the received voltage signal u3 into a 4-20mA current signal for output, including operational amplifiers U10, U11, and transistors Q1 and Q2; the in-phase input terminal of the operational amplifier U10 is connected to the second end of the resistor R23 to receive the voltage signal u3, and the in-phase input terminal of the operational amplifier U10 is also connected to a grounding resistor R24; the inverting input terminal of the operational amplifier U10 is connected to the emitter of the transistor Q1; the output terminal of the operational amplifier U10 is connected to the base of the transistor Q1, and the emitter of the transistor Q1 is connected in series with a resistor R 25 to ground, the collector of the transistor Q1 is connected in series with a resistor R26 and a diode D3 to a voltage source Ucc; the non-inverting input terminal of the operational amplifier U11 is connected in series with a resistor R28 to the emitter of the transistor Q1, and the non-inverting input of the operational amplifier U11 is also connected to a grounding capacitor C8; the reverse input terminal of the operational amplifier U11 is connected in series with a resistor R27 to the middle connection point of the resistor R26 and the diode D3; the output terminal of the operational amplifier U11 is connected to the base of the transistor Q2, the emitter of the transistor Q2 is connected to the inverting input terminal of the operational amplifier U11, and the emitter of the transistor Q2 is connected in series with an external sampling resistor RL to ground.

[0014] The utility model has the following beneficial effects:

[0015] The utility model converts the collected current signal into a voltage signal by setting a current / voltage conversion circuit, which is convenient for the subsequent circuit to perform lossless adjustment. The front-stage signal is amplified by the precision amplifier circuit, which can effectively realize the sampling of the lower limit signal; the DC signal is rectified and output by the precision rectifier circuit with voltage bias, which is convenient for the subsequent circuit to perform unipolar signal processing. The precision rectifier circuit with DC voltage bias is adopted to ensure that the front-stage signal can be transmitted to the next-stage circuit without loss. Some interference noise signals of the signal can be filtered out in the low-pass filter circuit to obtain a clean useful signal. Then, the bias voltage in the signal can be removed by the de-biasing circuit to obtain a complete usable signal. According to the requirements of the circuit, the signal can be transmitted in the form of voltage, and can also be further converted into a 4-20mA standard signal output by the voltage / current conversion circuit, which can effectively ensure the lossless transmission of the signal. After filtering, the signal is converted into a standard signal by the de-biasing circuit, which can maximize the accuracy of the system.

[0016] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 It is a topological block diagram of a voltage and current sampling and conversion device;

[0019] Figure 2 It is a current / voltage conversion circuit and precision amplifier circuit diagram;

[0020] Figure 3 It is a precision rectifier circuit and low-pass filter circuit diagram with voltage bias;

[0021] Figure 4 It is a circuit diagram of voltage bias removal circuit and current voltage output selection circuit;

[0022] Figure 5 It is a voltage / current conversion circuit diagram;

[0023] Figure 6 It is another form of the precision rectifier circuit and low-pass filter circuit with voltage bias mentioned in the second embodiment. DETAILED DESCRIPTION

[0024] With the rapid development of automation technology, all walks of life have paid much attention to the collection and conversion of electrical signals such as current and voltage. In particular, the demand for high-precision conversion of current and voltage signals is getting higher and higher. It has always been a difficult problem to convert signals with a wide range and high precision. This application solves this problem by setting up a voltage and current sampling and conversion device.

[0025] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0026] Embodiment 1:

[0027] See also Figure 1-5 As shown, the utility model is a voltage-current sampling and conversion device, comprising a current / voltage conversion circuit, a precision rectifier circuit with voltage bias, and a debiasing circuit;

[0028] The current / voltage conversion circuit converts the collected AC current signal into a voltage signal and transmits it to the precision amplifier circuit for amplification processing; the precision rectifier circuit with voltage bias receives the AC voltage transmitted by the precision amplifier circuit and performs rectification processing to output a DC voltage signal to the low-pass filter circuit for filtering processing; the de-biasing circuit receives the voltage signal output by the low-pass filter circuit for processing, and directly outputs the voltage signal after passing through the current and voltage output selection circuit or converts it into a current signal through the voltage / current conversion circuit for output; in this technical solution, a precision amplifier circuit and a precision rectifier circuit with voltage bias are used. It can effectively ensure the lossless transmission of the signal, and after filtering, the signal is converted into a standard signal through the de-biasing circuit, which can maximize the accuracy of the system.

[0029] It can be understood that in order to facilitate the subsequent circuit to perform lossless adjustment and effectively implement the sampling of the lower limit signal, the external current / voltage signal is converted into a voltage signal by the current / voltage conversion circuit, and then the front-stage signal is amplified by the precision amplifier circuit; specifically, Figure 2 As shown, the current / voltage conversion circuit in the utility model includes a resistor RS, which is connected to the current to be measured to convert the current signal into a voltage signal and then transmit it to the precision amplifier circuit. The precision amplifier circuit is used to amplify the received voltage signal, and includes operational amplifiers U1, U2, U3 and U4. U1, U2, U3 and R1, R2, R3, R4 and other circuits constitute a precision amplifier circuit, and R5, C1 and U4 constitute a primary filtering circuit.

[0030] The non-inverting input terminal of the operational amplifier U1 is connected to one end of the resistor RS, and the non-inverting input terminal of the operational amplifier U2 is connected to the other end of the resistor RS; the inverting input terminal of the operational amplifier U1 is connected in series with the resistor R1 to the inverting input terminal of the operational amplifier U2; the inverting input terminal of the operational amplifier U1 is connected in series with the resistor R2 to the operational amplifier U1; the inverting input terminal of the operational amplifier U2 is connected in series with the resistor R201 to the output terminal; the output terminal of the operational amplifier U1 is connected in series with the resistor R30 to the inverting input terminal of the operational amplifier U3, and the output terminal of the operational amplifier U2 is connected in series with the resistor R 31 to the non-inverting input terminal of the operational amplifier U3, and the resistor R31 is also connected in series with the resistor R41 to ground; the input terminal of the operational amplifier U3 is connected in series with the resistor R40 to the output terminal; the output terminal of the operational amplifier U3 is connected in series with the resistor R5 to the non-inverting input terminal of the operational amplifier U4, and a grounding capacitor C1 is also connected between the resistor R5 and the non-inverting input terminal of the operational amplifier U4; the inverting input terminal of the operational amplifier U4 is connected to the output terminal, and the output terminal of the operational amplifier U4 outputs the amplified voltage signal u1 to the precision rectifier circuit with voltage bias.

[0031] It can be understood that in order to facilitate the subsequent circuit to process unipolar signals, the present application can realize the conversion of AC signals into DC signals by setting a precision rectifier circuit with voltage bias, so as to ensure that the previous stage signal can be transmitted to the next stage circuit without loss. Specifically, Figure 3 As shown, the precision rectifier circuit with voltage bias in the utility model is used to rectify the received alternating current and output direct current to the low-pass filter circuit, including an operational amplifier U5 and a resistor R8; U5 and R6, R7, R8 and D1, D2 constitute a precision rectifier circuit with voltage bias; the inverting input terminal of the operational amplifier U5 is connected in series with resistors R7 and R6 in sequence to the output terminal of the operational amplifier U4 to receive the voltage signal u1, and the non-inverting input terminal of the operational amplifier U5 is grounded; the output terminal of the operational amplifier U5 is connected in series with a diode D2 to the low-pass filter circuit, and the inverting input terminal of the operational amplifier U5 is connected in series with a diode D1 to the output terminal; one end of the resistor R8 is connected to the middle connection point of the resistors R7 and R6, and the other end of the resistor R8 is connected to the cathode of the diode D2;

[0032] It can be understood that in order to filter out the noise in the signal, the present application can filter out some interfering noise signals of the signal by setting a low-pass filter circuit to obtain a clean useful signal; specifically, Figure 3As shown, the low-pass filter circuit in the utility model is used to filter the rectified DC power, and the low-pass filter circuit includes operational amplifiers U6 and U7; U6, U7 and R9, R10, R11, R12, R13, R14 and C2, C3, C4, C5 together form a high-order low-pass filter; the in-phase input terminal of the operational amplifier U6 is connected in series with resistors R10 and R9 to the cathode of the diode D2; the inverting input terminal of the operational amplifier U6 is connected in series with resistor R11 to the output terminal; a grounding resistor is connected between the in-phase input terminal of the operational amplifier U6 and the resistor R10 Capacitor C2; the middle connection point of resistors R10 and R9 is connected in series with capacitor C3 to the output end of operational amplifier U6; the output end of operational amplifier U6 is connected in series with resistor R12 to the non-inverting input end of operational amplifier U7; a grounded capacitor C4 is connected between the non-inverting input end of operational amplifier U7 and resistor R12; the inverting input end of operational amplifier U7 is connected in series with resistor R13 to ground, and the output end of operational amplifier U7 outputs the filtered voltage signal u2 to the de-biasing circuit; the inverting input end of operational amplifier U7 is connected in series with resistor R14 to the output end, and both ends of resistor R14 are connected in parallel with capacitor C5.

[0033] It can be understood that in order to obtain a clean usable signal, the present application sets a debiasing circuit, specifically, as Figure 4 As shown, the de-biasing circuit in the utility model is used to remove the bias voltage in the signal, including operational amplifiers U8, U9 and resistor R21; operational amplifiers U8, U9 and R15, R16, R17, R18, R19, R20, R21 constitute a de-biasing circuit, and U9 and R19 as well as C6 and C7 constitute a two-order low-pass filter to further filter the signal.

[0034] The operational amplifier U8 is connected in series with resistor R15 to the reference voltage source Uref; resistor R15 is also connected in series with resistor R16 to ground, and the inverting input terminal of the operational amplifier U8 is connected to the output terminal; the output terminal of the operational amplifier U8 is connected in series with resistor R17 to the non-inverting input terminal of the operational amplifier U9, and the non-inverting input terminal of the operational amplifier U9 is also connected in series with resistor R18 to the output terminal of the operational amplifier U7 to receive the voltage signal u2; the inverting input terminal of the operational amplifier U9 is connected in series with resistor R20 to ground, and the inverting input terminal of the operational amplifier U9 is also connected in series with capacitor C6 to the output terminal; the output terminal of the operational amplifier U9 is connected in series with resistor R19 to the current and voltage output selection circuit; one end of resistor R21 is connected to the inverting input terminal of the operational amplifier U9, and the other end of resistor R21 is connected to the middle connection point between resistor R19 and the current and voltage output selection circuit.

[0035] It is understandable that in order to expand the versatility of the device, the present application sets a current voltage output selection circuit, which can select the output current signal or voltage signal according to the needs of the circuit. Specifically, Figure 4As shown, the current and voltage output selection circuit in the utility model is used to select the output signal type of the circuit, including resistors R22 and R23; the first ends of resistors R22 and R23 are both connected to resistor R19, and the second end of resistor R22 outputs a voltage signal uo as a direct output; the second end of resistor R23 outputs a voltage signal u3 to the voltage / current conversion circuit for conversion.

[0036] Based on the above, Figure 5 As shown, the voltage / current conversion circuit is used to convert the received voltage signal u3 into a 4-20mA current signal for output, including operational amplifiers U10, U11, and transistors Q1 and Q2; the in-phase input terminal of the operational amplifier U10 is connected to the second end of the resistor R23 to receive the voltage signal u3, and the in-phase input terminal of the operational amplifier U10 is also connected to the grounding resistor R24; the inverting input terminal of the operational amplifier U10 is connected to the emitter of the transistor Q1; the output terminal of the operational amplifier U10 is connected to the base of the transistor Q1, the emitter of the transistor Q1 is connected in series with the resistor R25 to ground, and the collector of the transistor Q1 is connected in series with the resistor R26, diode D3 to voltage source Ucc; the non-inverting input terminal of the operational amplifier U11 is connected in series with resistor R28 to the emitter of the transistor Q1, and the non-inverting input of the operational amplifier U11 is also connected to a grounding capacitor C8; the reverse input terminal of the operational amplifier U11 is connected in series with resistor R27 to the middle connection point between resistor R26 and diode D3; the output terminal of the operational amplifier U11 is connected to the base of the transistor Q2, the emitter of the transistor Q2 is connected to the inverting input terminal of the operational amplifier U11, and the emitter of the transistor Q2 is connected in series with an external sampling resistor RL to ground, and the voltage signal can be converted into a current signal for output through the resistor RL.

[0037] It is worth noting that in the above system embodiment, the various units included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of the functional units are only for the convenience of distinguishing each other, and are not used to limit the protection scope of the present utility model.

[0038] In addition, a person skilled in the art can understand that all or part of the steps in the above-mentioned embodiments can be completed by instructing related hardware through a program, and the corresponding program can be stored in a computer-readable storage medium, such as a ROM / RAM, a disk or an optical disk.

[0039] The preferred embodiments of the utility model disclosed above are only used to help explain the utility model. The preferred embodiments do not describe all the details in detail, nor do they limit the utility model to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the utility model, so that technicians in the relevant technical field can well understand and use the utility model. The utility model is limited only by the claims and their full scope and equivalents.

Claims

1. A voltage and current sampling and conversion device, characterized in that: include A current / voltage conversion circuit, which converts the collected AC current signal into a voltage signal and transmits it to a precision amplifier circuit for amplification processing; A precision rectifier circuit with voltage bias, which receives the AC voltage transmitted by the precision amplifier circuit and performs rectification processing to output a DC voltage signal to a low-pass filter circuit for filtering; A de-biasing circuit receives the voltage signal output by the low-pass filtering circuit for processing, and directly outputs the voltage signal after passing through a current-voltage output selection circuit or converts it into a current signal through a voltage / current conversion circuit for output.

2. A voltage and current sampling and conversion device according to claim 1, characterized in that: The current / voltage conversion circuit includes a resistor RS, and the resistor RS is connected to the current to be measured to convert the current signal into a voltage signal and then transmit it to the precision amplifier circuit.

3. A voltage and current sampling and conversion device according to claim 2, characterized in that: The precision amplifier circuit is used to amplify the received voltage signal, and includes operational amplifiers U1, U2, U3 and U4; The non-inverting input terminal of the operational amplifier U1 is connected to one end of the resistor RS, and the non-inverting input terminal of the operational amplifier U2 is connected to the other end of the resistor RS; the inverting input terminal of the operational amplifier U1 is connected in series with the resistor R1 to the inverting input terminal of the operational amplifier U2; The inverting input terminal of the operational amplifier U1 is connected in series with a resistor R2 to the operational amplifier U1; the inverting input terminal of the operational amplifier U2 is connected in series with a resistor R201 to the output terminal; The output end of the operational amplifier U1 is connected in series with a resistor R30 to the inverting input end of the operational amplifier U3, the output end of the operational amplifier U2 is connected in series with a resistor R31 to the non-inverting input end of the operational amplifier U3, and the resistor R31 is also connected in series with a resistor R41 to ground; The input end of the operational amplifier U3 is connected in series with a resistor R40 to the output end; The output end of the operational amplifier U3 is connected in series with a resistor R5 to the non-inverting input end of the operational amplifier U4, and a grounding capacitor C1 is also connected between the resistor R5 and the non-inverting input end of the operational amplifier U4; the inverting input end of the operational amplifier U4 is connected to the output end, and the output end of the operational amplifier U4 outputs the amplified voltage signal u1 to a precision rectifier circuit with voltage bias.

4. A voltage and current sampling and conversion device according to claim 3, characterized in that: The precision rectifier circuit with voltage bias is used to rectify the received alternating current to output direct current, and includes an operational amplifier U5 and a resistor R8; The inverting input terminal of the operational amplifier U5 is connected in series with resistors R7 and R6 in sequence to the output terminal of the operational amplifier U4 to receive the voltage signal u1, and the non-inverting input terminal of the operational amplifier U5 is grounded; The output end of the operational amplifier U5 is connected in series with a diode D2 to a low-pass filter circuit, and the inverting input end of the operational amplifier U5 is connected in series with a diode D1 to the output end; One end of the resistor R8 is connected to the middle connection point of the resistors R7 and R6, and the other end of the resistor R8 is connected to the cathode of the diode D2.

5. A voltage and current sampling and conversion device according to claim 4, characterized in that: The low-pass filter circuit is used to filter the rectified direct current, and the low-pass filter circuit includes operational amplifiers U6 and U7; The in-phase input terminal of the operational amplifier U6 is connected in series with resistors R10 and R9 to the cathode of the diode D2; the inverting input terminal of the operational amplifier U6 is connected in series with resistor R11 to the output terminal; A grounding capacitor C2 is connected between the in-phase input terminal of the operational amplifier U6 and the resistor R10; a capacitor C3 is connected in series to the output terminal of the operational amplifier U6 at the intermediate connection point of the resistors R10 and R9; The output end of the operational amplifier U6 is connected in series with a resistor R12 to the non-inverting input end of the operational amplifier U7; a grounding capacitor C4 is connected between the non-inverting input end of the operational amplifier U7 and the resistor R12; The inverting input terminal of the operational amplifier U7 is connected in series with a resistor R13 to ground, and the output terminal of the operational amplifier U7 outputs the filtered voltage signal u2 to the de-biasing circuit; the inverting input terminal of the operational amplifier U7 is connected in series with a resistor R14 to the output terminal, and both ends of the resistor R14 are connected in parallel with the capacitor C5.

6. A voltage and current sampling and conversion device according to claim 5, characterized in that: The debiasing circuit is used to remove the bias voltage in the signal, and includes operational amplifiers U8, U9 and resistor R21; The operational amplifier U8 is connected in series with a resistor R15 to a reference voltage source Uref; the resistor R15 is also connected in series with a resistor R16 to ground, and the inverting input terminal of the operational amplifier U8 is connected to the output terminal; The output end of the operational amplifier U8 is connected in series with a resistor R17 to the non-inverting input end of the operational amplifier U9, and the non-inverting input end of the operational amplifier U9 is also connected in series with a resistor R18 to the output end of the operational amplifier U7 to receive the voltage signal u2; The inverting input terminal of the operational amplifier U9 is connected in series with a resistor R20 to ground, and the inverting input terminal of the operational amplifier U9 is also connected in series with a capacitor C6 to the output terminal; The output end of the operational amplifier U9 is connected in series with a resistor R19 to a current and voltage output selection circuit; One end of the resistor R21 is connected to the inverting input end of the operational amplifier U9, and the other end of the resistor R21 is connected to the middle connection point between the resistor R19 and the current and voltage output selection circuit.

7. The voltage and current sampling and conversion device according to claim 6, characterized in that: The current and voltage output selection circuit is used to select the output signal type of the circuit, including resistors R22 and R23; the first ends of the resistors R22 and R23 are both connected to the resistor R19, and the second end of the resistor R22 outputs the voltage signal uo as a direct output; the second end of the resistor R23 outputs the voltage signal u3 to the voltage / current conversion circuit for conversion.

8. The voltage and current sampling and conversion device according to claim 7, characterized in that: The voltage / current conversion circuit is used to convert the received voltage signal u3 into a 4-20mA current signal for output, and includes operational amplifiers U10 and U11, and transistors Q1 and Q2; The in-phase input terminal of the operational amplifier U10 is connected to the second end of the resistor R23 to receive the voltage signal u3, and the in-phase input terminal of the operational amplifier U10 is also connected to the grounding resistor R24; the inverting input terminal of the operational amplifier U10 is connected to the emitter of the transistor Q1; The output end of the operational amplifier U10 is connected to the base of the transistor Q1, the emitter of the transistor Q1 is connected in series with a resistor R25 to ground, and the collector of the transistor Q1 is connected in series with a resistor R26 and a diode D3 to a voltage source Ucc; The in-phase input terminal of the operational amplifier U11 is connected in series with a resistor R28 to the emitter of the transistor Q1, and the in-phase input of the operational amplifier U11 is also connected to a grounding capacitor C8; the in-phase input terminal of the operational amplifier U11 is connected in series with a resistor R27 to the middle connection point of the resistor R26 and the diode D3; The output end of the operational amplifier U11 is connected to the base of the transistor Q2, the emitter of the transistor Q2 is connected to the inverting input end of the operational amplifier U11, and the emitter of the transistor Q2 is connected in series with an external sampling resistor RL to ground.

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