Rogowski coil signal conditioning circuit and circuit breaker

Abstract

The utility model discloses a Rogowski coil signal conditioning circuit and a circuit breaker. The Rogowski coil signal conditioning circuit comprises an active integrating circuit module, two input ends of which are connected to two signal output ends of a Rogowski coil, and which is used for integrating induced voltage signals of the Rogowski coil; the amplifying circuit module is used for amplifying the electric signal output by the active integrating circuit module and then outputting the amplified electric signal; the reference voltage pull-up module comprises pull-up resistors, one ends of the two resistors are connected to the two input ends of the active integrating circuit module respectively, and the other ends of the two resistors are connected to the same reference voltage, so that the two signal output ends of the Rogowski coil are pulled up to the reference voltage through the resistors respectively; and the reference voltage power supply circuit module is used for generating the reference voltage. The circuit breaker is provided with the Rogowski coil signal conditioning circuit. According to the Rogowski coil signal conditioning circuit and the circuit breaker, errors caused by circuit offset voltage can be reduced, and the measurement precision is improved.

Description

Technical Field

[0001] The utility model relates to the field of circuit breakers, in particular to a current sampling signal conditioning circuit applied to a circuit breaker. Background Art

[0002] The Rogowski Coil, also known as the Rogowski coil or the Roche coil, is an alternating current sensor. As a core component of a circuit breaker, the Rogowski coil and its signal conditioning circuit can be used to accurately measure the electrical signal of the measured current and provide it to the microprocessor (Microcontroller Unit, MCU) of the electronic tripping unit of the circuit breaker for AD sampling to achieve subsequent logic operation control. Therefore, it is very important to improve the measurement accuracy as much as possible.

[0003] The induced voltage of the Rogowski coil is proportional to the derivative of the measured current with respect to time. Therefore, the Rogowski coil is equivalent to having a differentiating function, and its signal conditioning circuit needs to perform an integration process on the induced voltage of the Rogowski coil. The current Rogowski coil signal conditioning circuit uses an active integration circuit and an amplification circuit composed of operational amplifiers and is directly connected to the Rogowski coil, and cannot solve the error caused by the circuit offset voltage. In addition, the current Rogowski coil signal conditioning circuits all use a single-channel output method and cannot fully meet the requirements for the protection and measurement of the electronic tripping unit of the circuit breaker. Summary of the Utility Model

[0004] For this reason, in view of at least one of the above problems, the utility model provides a Rogowski coil signal conditioning circuit and a circuit breaker.

[0005] The utility model is implemented as follows:

[0006] A Rogowski coil signal conditioning circuit for conditioning and outputting the signal of a connected Rogowski coil, comprising:

[0007] An active integration circuit module, the two input ends of which are connected to the two signal output ends of the Rogowski coil, for performing an integration process on the induced voltage signal of the Rogowski coil to restore the associated electrical signal and output it;

[0008] An amplification circuit module, the input end of which is connected to the output end of the active integration circuit module, for amplifying the electrical signal output by the active integration circuit module and then outputting it;

[0009] A reference voltage pull-up module, including at least two pull-up resistors, one end of each of the two resistors is respectively connected to the two input ends of the active integration circuit module, and the other end is connected to a reference voltage to respectively pull up the two signal output ends of the Rogowski coil to the reference voltage through the resistors;

[0010] A reference voltage power supply circuit module is used to generate the reference voltage.

[0011] Wherein, in one embodiment, the Rogowski coil signal conditioning circuit includes two output terminals, namely a large current channel output terminal and a small current channel output terminal. The large current channel output terminal is constructed from the output terminal of the active integration circuit module, and the small current channel output terminal is constructed from the output terminal of the amplifier circuit module. Both the large current channel output terminal and the small current channel output terminal are synchronously provided to the microprocessor of the circuit breaker for AD sampling.

[0012] Wherein, in one embodiment, the output terminal of the active integration circuit module is divided into two paths. The first path is directly connected to construct the large current channel output terminal, and the second path is connected to the input terminal of the amplifier circuit module.

[0013] Wherein, in one embodiment, the first path of the output terminal of the active integration circuit module and / or the output terminal of the amplifier circuit module are also connected to an RC filtering unit before output.

[0014] Wherein, in one embodiment, the active integration circuit module includes an active integration differential amplifier circuit composed of a first input terminal resistor R80, a second input terminal resistor R82, a first matching resistor R85, an integration operational amplifier U11C, a first feedback resistor R78, and an integration capacitor C73. Specifically: the inverting input terminal and the non-inverting input terminal of the integration operational amplifier U11C are respectively connected in series with the first input terminal resistor R80 and the second input terminal resistor R82. The non-inverting input terminal of the integration operational amplifier U11C is also connected to the reference voltage via the first matching resistor R85. Both the first feedback resistor R78 and the integration capacitor C73 are respectively connected in parallel between the inverting input terminal and the output terminal of the integration operational amplifier U11C.

[0015] Wherein, in one embodiment, the active integration circuit module further includes a first filtering capacitor C74 and a first matching capacitor C77. The two ends of the first filtering capacitor C74 are connected in parallel between the inverting input terminal and the non-inverting input terminal of the integration operational amplifier U11C, and the two ends of the first matching capacitor C77 are connected in parallel between the two ends of the first matching resistor R85.

[0016] Among them, in one embodiment, the amplifier circuit module includes a third input terminal resistor R83, a second low-pass filter capacitor C79, a low-pass filter resistor R86, a fourth input terminal resistor R87, a second operational amplifier U12C, a second feedback resistor R81, and a first low-pass filter capacitor C76, which form a multiple-feedback amplifier circuit with second-order filtering. Among them: one end of the third input terminal resistor R83 is connected to the output terminal of the active integration circuit module 20, and the other end is connected to the inverting input terminal of the second operational amplifier U12C after being serially connected with the low-pass filter resistor R86. One end of the fourth input terminal resistor R87 is connected to the reference voltage, and the other end is connected to the non-inverting input terminal of the second operational amplifier U12C. The middle node between the third input terminal resistor R83 and the low-pass filter resistor R86 is grounded via the second low-pass filter capacitor C79. Both ends of the second feedback resistor R81 are respectively connected to the middle node between the third input terminal resistor R83 and the low-pass filter resistor R86 and the output terminal of the second operational amplifier U12C. Both ends of the first low-pass filter capacitor C76 are respectively connected to the inverting input terminal and the output terminal of the second operational amplifier U12C.

[0017] Among them, in one embodiment, the reference voltage power supply circuit module includes an LC filtering unit, a voltage stabilizing reference unit, a voltage dividing unit, a capacitor filtering unit, a voltage follower unit, and an RC filtering unit connected in series in sequence. The LC filtering unit is connected to the input first voltage, and the RC filtering unit outputs a second voltage, that is, the reference voltage, and the first voltage is higher than the second voltage.

[0018] Among them, in one embodiment, the LC filtering unit includes a filtering inductor FB1 and a filtering capacitor C53 connected in series; the voltage stabilizing reference unit includes a three-terminal reference chip U9, whose Vin terminal is connected to the middle node between the filtering inductor FB1 and the filtering capacitor C53, and a capacitor C20 is connected between its Vout terminal and GND terminal, and its GND terminal is grounded; the voltage dividing unit includes a voltage dividing resistor R125 and a voltage dividing resistor R124 connected in series. The first end of the voltage dividing resistor R125 is connected to the Vout terminal of the three-terminal reference chip U9, and the second end of the voltage dividing resistor R124 is grounded; the capacitor filtering unit includes a filtering capacitor C113, and both ends of it are respectively connected to the middle node between the voltage dividing resistor R125 and the voltage dividing resistor R124 and grounded; the voltage follower unit includes an operational amplifier U16, whose non-inverting input terminal is connected to one end of the filtering capacitor C113, and its inverting input terminal is connected to its output terminal; the LC filtering unit includes a resistor R126 and a filtering capacitor C110 connected in series.

[0019] In addition, a circuit breaker is further provided, including: an electronic tripping unit, the electronic tripping unit includes a microprocessor, the microprocessor has an AD sampling port, and further includes: a Rogowski coil and a Rogowski coil signal conditioning circuit connected to the Rogowski coil, and the Rogowski coil signal conditioning circuit is any one of the Rogowski coil signal conditioning circuits described above.

[0020] Through the technical solution provided by the present utility model, the following technical effects are achieved:

[0021] 1. The signal input end of the Rogowski coil signal conditioning circuit connected to the two output ends of the Rogowski coil is also pulled up to the reference voltage through a pull-up resistor, so as to reduce the error caused by the circuit offset voltage and improve the measurement accuracy;

[0022] 2. The Rogowski coil signal conditioning circuit adopts a dual output channel mode of large current output and small current output, so that the microprocessor of the electronic tripping unit of the circuit breaker can perform synchronous calculation in dual channels, thereby enabling a faster circuit breaking measurement and protection function;

[0023] 3. The Rogowski coil signal conditioning circuit adopts a dual output channel. The small current signal channel can adopt a larger amplification factor to increase the signal amplitude, enhance the signal-to-noise ratio of the channel, and improve the measurement accuracy for measuring current sampling; the large current channel adopts an integral attenuation method to increase the measurement range for electronic protection current sampling. Description of the Drawings

[0024] Figure 1 is a circuit module diagram of an embodiment of the present utility model;

[0025] Figure 2 is a circuit schematic diagram of the main part (excluding the reference voltage power supply circuit module) of an embodiment of the present utility model;

[0026] Figure 3 is a circuit schematic diagram of the reference voltage power supply circuit module part of an embodiment of the present utility model. Detailed Embodiments

[0027] To further illustrate each embodiment, the present utility model provides drawings. These drawings are a part of the disclosure of the present utility model, which are mainly used to illustrate the embodiments and can be used to explain the operating principle of the embodiments in combination with the relevant descriptions in the specification. With reference to these contents, those of ordinary skill in the art should be able to understand other possible implementation manners and the advantages of the present utility model. The components in the drawings are not drawn to scale, and similar component symbols are usually used to represent similar components.

[0028] The present utility model will be further described below in conjunction with the drawings and specific embodiments.

[0029] AsFigure 1 As shown in the figure, the present utility model provides a circuit module diagram of an embodiment of a Rogowski coil signal conditioning circuit, including: an active integration circuit module 20, whose two input terminals are connected to the two signal output terminals IIB1 and IIB2 of the Rogowski coil 10, and is used for integrating the induced voltage signal of the Rogowski coil 10 to restore and output the associated electrical signal; an amplification circuit module 30, whose input terminal is connected to the output terminal of the active integration circuit module 20, and is used for amplifying and outputting the electrical signal output by the active integration circuit module 20; a reference voltage pull-up module 40, which includes at least two pull-up impedance components. One ends of the two impedance components are respectively connected to the two input terminals of the active integration circuit module 20, and the other ends are connected to the reference voltage Vref_1.5V to respectively pull up the two signal output terminals of the Rogowski coil to the reference voltage Vref_1.5V through the impedance components; a reference voltage power supply circuit module 50, which is used for generating the reference voltage Vref_1.5V.

[0030] In one embodiment, the impedance components of the reference voltage pull-up module 40 are resistors. The two signal output terminals IIB1 and IIB2 of the Rogowski coil 10 are respectively pulled up to the reference voltage Vref_1.5V through the pull-up resistors R79 and R84 to reduce the error caused by the circuit offset voltage.

[0031] Compared with the prior art, in this embodiment of the Rogowski coil signal conditioning circuit, the signal input terminals IIB1 and IIB2 connecting the two output terminals of the Rogowski coil 10 are also pulled up to the reference voltage Vref_1.5V through the reference voltage pull-up module 40, so as to reduce the error caused by the circuit offset voltage and improve the measurement accuracy.

[0032] Refer to Figure 2 and Figure 3 As shown in the figure, the specific circuits of each module are described as follows:

[0033] In one embodiment, the active integration circuit module 20 includes an active integration differential amplification circuit composed of a first input terminal resistor R80, a second input terminal resistor R82, a first matching resistor R85, an integration operational amplifier U11C, a first feedback resistor R78, and an integration capacitor C73. Among them: the inverting input terminal and the non-inverting input terminal of the integration operational amplifier U11C are respectively connected in series with the first input terminal resistor R80 and the second input terminal resistor R82. The non-inverting input terminal of the integration operational amplifier U11C is also connected to the reference voltage through the first matching resistor R85. The first feedback resistor R78 and the integration capacitor C73 are respectively connected in parallel between the inverting input terminal and the output terminal of the integration operational amplifier U11C.

[0034] Since the induced voltage of the Rogowski coil 10 is proportional to the derivative of the measured current with respect to time, the Rogowski coil 10 is equivalent to an electronic component with a differentiating function. The first input resistor R80 and the second input resistor R82 at the two input terminals of the active integration circuit module 20 are connected to the two signal output terminals IIB1 and IIB2 of the Rogowski coil 10, and are used to perform integration processing on the induced voltage signal of the Rogowski coil 10 to restore and output the associated electrical signal.

[0035] To avoid interference and further improve the measurement accuracy, preferably, the active integration circuit module 20 further includes a first filter capacitor C74 and a first matching capacitor C77. The two ends of the first filter capacitor C74 are connected in parallel to the inverting input terminal and the non-inverting input terminal of the integration operational amplifier U11C, and the two ends of the first matching capacitor C77 are connected in parallel to the two ends of the first matching resistor R85.

[0036] It should be noted that since the integration operational amplifier U11C in this embodiment is powered by a single power supply, the non-inverting input terminal of the integration operational amplifier U11C needs to be connected to the reference voltage Vref_1.5V through the first matching resistor R85 in parallel with the first matching capacitor C77. If the power supply of the integration operational amplifier U11C in this embodiment uses a power supply including a positive power supply and a negative power supply, then the reference voltage Vref_1.5V does not need to be connected.

[0037] In one embodiment, the amplifier circuit module 30 includes a third input terminal resistor R83, a second low-pass filter capacitor C79, a low-pass filter resistor R86, a fourth input terminal resistor R87, a second operational amplifier U12C, a second feedback resistor R81, and a first low-pass filter capacitor C76, which form a multiple-feedback amplifier circuit with second-order filtering. Among them, a feedback amplifier circuit is formed by the third input terminal resistor R83, the fourth input terminal resistor R87, the second feedback resistor R81, and the second operational amplifier U12C, so as to amplify the electrical signal output by the active integration circuit module 20 twice. A second-order low-pass filter is formed by the second feedback resistor R81, the first low-pass filter capacitor C76, the low-pass filter resistor R86, the second low-pass filter capacitor C79, and the second operational amplifier U12C, so as to effectively filter out interference, and finally output an electrical signal that is amplified again and stable and accurate (i.e., the output electrical signal of the small current channel, which will be further described below) to the microprocessor of the circuit breaker for AD sampling. Specifically: one end of the third input terminal resistor R83 is connected to the output terminal of the active integration circuit module 20 (i.e., the output terminal of the integration operational amplifier U11C), and the other end is connected to the inverting input terminal of the second operational amplifier U12C after being connected in series with the low-pass filter resistor R86. One end of the fourth input terminal resistor R87 is connected to the reference voltage Vref_1.5V, and the other end is connected to the non-inverting input terminal of the second operational amplifier U12C. The middle node of the third input terminal resistor R83 and the low-pass filter resistor R86 is grounded through the second low-pass filter capacitor C79. Both ends of the second feedback resistor R81 are respectively connected to the middle node of the third input terminal resistor R83 and the low-pass filter resistor R86 and the output terminal of the second operational amplifier U12C. Both ends of the first low-pass filter capacitor C76 are respectively connected to the inverting input terminal and the output terminal of the second operational amplifier U12C.

[0038] In one embodiment, the reference voltage power supply circuit module 50 includes an LC filtering unit, a voltage stabilizing reference unit, a voltage dividing unit, a capacitor filtering unit, a voltage follower unit, and an RC filtering unit connected in series in sequence. The LC filtering unit is connected to the input first voltage DC3.3V, and the RC filtering unit outputs a second voltage DC1.5V, that is, the reference voltage Vref_1.5V.

[0039] Specifically, refer to Figure 3As shown, the LC filtering unit includes a filtering inductor FB1 and a filtering capacitor C53 connected in series; the voltage stabilizing reference unit includes a three-terminal reference chip U9 (the three-terminal reference chip U9 selects a high-precision, low-temperature drift, and low-noise reference chip, such as the REF3030 model), whose Vin terminal is connected to the intermediate node of the filtering inductor FB1 and the filtering capacitor C53, a capacitor C20 is connected between its Vout terminal and the GND terminal, and its GND terminal is grounded; the voltage dividing unit includes a voltage dividing resistor R125 and a voltage dividing resistor R124 connected in series, the first end of the voltage dividing resistor R125 is connected to the Vout terminal of the three-terminal reference chip U9, and the second end of the voltage dividing resistor R124 is grounded; the capacitor filtering unit includes a filtering capacitor C113, and its two ends are respectively connected to the intermediate node of the voltage dividing resistor R125 and the voltage dividing resistor R124 and grounded; the voltage follower unit includes an operational amplifier U16, whose non-inverting input terminal is connected to one end of the filtering capacitor C113, and its inverting input terminal is connected to its output terminal; the LC filtering unit includes a resistor R126 and a filtering capacitor C110 connected in series. Preferably, in this embodiment, on the basis of the tantalum electrolytic capacitor or solid capacitor C20 and C110, a small ceramic capacitor C111 and C1112 can be respectively connected in parallel to further improve the filtering effect.

[0040] The reference voltage power supply circuit module 50 is implemented by the above circuit unit, and can output a relatively accurate reference voltage Vref_1.5V, providing an accurate zero-point reference for the active integration circuit module 20 and the amplifier circuit module 30 to improve the measurement accuracy. This circuit uses a dedicated reference voltage chip to generate a reference source of VREF_3V from the input DC3.3V voltage to provide a reference voltage for analog voltage acquisition; VREF_3V is input to the positive input end of the operational amplifier through resistor voltage division, and then the reference voltage Vref_1.5V is output through the emitter follower circuit composed of the operational amplifier, providing a zero-point reference for the subsequent amplifier circuit (i.e., the active integration circuit module 20 and the amplifier circuit module 30).

[0041] In this embodiment, the Rogowski coil signal conditioning circuit includes two output terminals, namely the large current channel output terminal IB1 and the small current channel output terminal IB2. The large current channel output terminal IB1 is constructed from the output terminal of the active integration circuit module 20, and the small current channel output terminal IB2 is constructed from the output terminal of the amplifier circuit module 30. The large current channel output terminal IB1 and the small current channel output terminal IB2 are both synchronously provided to the microprocessor of the circuit breaker for AD sampling. Specifically, the output terminal of the active integration circuit module 20 is divided into two paths. The first path is directly connected to construct the large current channel output terminal IB1, and the second path is connected to the input terminal of the amplifier circuit module 30. The output terminal of the amplifier circuit module 30 is directly connected to construct the small current channel output terminal IB2.

[0042] To avoid output interference and further improve the measurement accuracy, preferably, the first path of the output terminal of the active integration circuit module 20 is further connected to an RC filtering unit composed of a resistor R55 and a capacitor C46 before output. Moreover, the output terminal of the amplifier circuit module 30 is further connected to an RC filtering unit composed of a resistor R56 and a capacitor C47 before output.

[0043] In this embodiment, the Rogowski coil signal conditioning circuit adopts two-stage cascaded amplifier circuits (the active integration circuit module 20 and the amplifier circuit module 30), and outputs to the AD sampling port of the microprocessor of the electronic trip unit at different amplification multiples. The first stage uses the active integration circuit module 20. The output of the large current channel adopts an integral attenuation method to increase the measurement range, and can be used for sampling the protection current of the electronic type, so as to be used in the measurement of short-circuit short-time delay and instantaneous protection current; the second stage uses the amplifier circuit module 30 of the multiple feedback amplifier circuit for secondary amplification, and a larger amplification multiple can be adopted to output the signal of the small current channel, increase the signal amplitude, enhance the signal-to-noise ratio of the channel, improve the measurement accuracy, and can be used for sampling the metering current, so as to be used in the measurement of overload and metering current. Since the Rogowski coil signal conditioning circuit of the present invention adopts a dual-channel output, the microprocessor of the electronic trip unit can sample simultaneously and calculate synchronously to achieve a fast protection function. The microprocessor of the electronic trip unit switches the sampling of the two channels by comparing the AD values of the two channels. When it is greater than 2In, the data output from the output terminal IB1 of the large current channel is adopted, and when it is less than 2In, the data output from the output terminal IB2 of the small current channel is adopted.

[0044] In addition, the present invention also provides a circuit breaker, including: an electronic trip unit, the electronic trip unit includes a microprocessor, the microprocessor has an AD sampling port, and further includes: a Rogowski coil and a Rogowski coil signal conditioning circuit connected to the Rogowski coil, and the Rogowski coil signal conditioning circuit is the Rogowski coil signal conditioning circuit as described in any one of the above. Since the Rogowski coil signal conditioning circuit of the circuit breaker adopts the above structure, it also has the beneficial technical effects of the Rogowski coil signal conditioning circuit of the above embodiment.

[0045] Although the present invention is specifically shown and introduced in combination with the preferred embodiments, those skilled in the art should understand that various changes can be made to the present invention in terms of form and details without departing from the spirit and scope of the present invention defined by the appended claims, and all of them are within the protection scope of the present invention.

Claims

1. A Rogowski coil signal conditioning circuit is used to condition the signal of the Rogowski coil connected thereto and output it, and is characterized in that Comprising: An active integration circuit module, whose two input terminals are connected to the two signal output terminals of the Rogowski coil, and is used for integrating the induced voltage signal of the Rogowski coil to restore and output the associated electrical signal; An amplification circuit module, whose input terminal is connected to the output terminal of the active integration circuit module, and is used for amplifying and outputting the electrical signal output by the active integration circuit module; A reference voltage pull-up module, at least including two pull-up resistors. One ends of the two resistors are respectively connected to the two input terminals of the active integration circuit module, and the other ends are connected to the reference voltage to respectively pull up the two signal output terminals of the Rogowski coil to the reference voltage through the resistors; A reference voltage power supply circuit module, which is used for generating the reference voltage.

2. The Rogowski coil signal conditioning circuit according to claim 1, wherein: The Rogowski coil signal conditioning circuit includes two output terminals, namely a large current channel output terminal and a small current channel output terminal. The large current channel output terminal is constructed by the output terminal of the active integration circuit module, and the small current channel output terminal is constructed by the output terminal of the amplification circuit module. Both the large current channel output terminal and the small current channel output terminal are synchronously provided to the microprocessor of the circuit breaker for AD sampling.

3. The Rogowski coil signal conditioning circuit according to claim 2, wherein: The output terminal of the active integration circuit module is divided into two paths. The first path is directly connected to construct the large current channel output terminal, and the second path is connected to the input terminal of the amplification circuit module.

4. The Rogowski coil signal conditioning circuit according to claim 3, wherein: The first path of the output terminal of the active integration circuit module and / or the output terminal of the amplification circuit module are also connected to an RC filtering unit and then output.

5. The Rogowski coil signal conditioning circuit according to claim 1, wherein: The active integration circuit module includes an active integration differential amplification circuit composed of a first input terminal resistor R80, a second input terminal resistor R82, a first matching resistor R85, an integration operational amplifier U11C, a first feedback resistor R78, and an integration capacitor C73. Among them: the inverting input terminal and the non-inverting input terminal of the integration operational amplifier U11C are respectively connected in series with the first input terminal resistor R80 and the second input terminal resistor R82. The non-inverting input terminal of the integration operational amplifier U11C is also connected to the reference voltage via the first matching resistor R85. Both the first feedback resistor R78 and the integration capacitor C73 are respectively connected in parallel between the inverting input terminal and the output terminal of the integration operational amplifier U11C.

6. The Rogowski coil signal conditioning circuit according to claim 5, wherein: The active integration circuit module also includes a first filtering capacitor C74 and a first matching capacitor C77. The two ends of the first filtering capacitor C74 are connected in parallel between the inverting input terminal and the non-inverting input terminal of the integration operational amplifier U11C, and the two ends of the first matching capacitor C77 are connected in parallel between the two ends of the first matching resistor R85.

7. The Rogowski coil signal conditioning circuit according to claim 1, characterized in that: The amplifier circuit module includes a third input terminal resistor R83, a second low-pass filter capacitor C79, a low-pass filter resistor R86, a fourth input terminal resistor R87, a second operational amplifier U12C, a second feedback resistor R81, and a first low-pass filter capacitor C76, which form a multiple-feedback amplifier circuit with a second-order filter. Among them: One end of the third input terminal resistor R83 is connected to the output terminal of the active integration circuit module (20), and the other end is connected to the inverting input terminal of the second operational amplifier U12C after being serially connected with the low-pass filter resistor R86. One end of the fourth input terminal resistor R87 is connected to the reference voltage, and the other end is connected to the non-inverting input terminal of the second operational amplifier U12C. The middle node between the third input terminal resistor R83 and the low-pass filter resistor R86 is grounded via the second low-pass filter capacitor C79. Both ends of the second feedback resistor R81 are respectively connected to the middle node between the third input terminal resistor R83 and the low-pass filter resistor R86 and the output terminal of the second operational amplifier U12C. Both ends of the first low-pass filter capacitor C76 are respectively connected to the inverting input terminal and the output terminal of the second operational amplifier U12C.

8. The Rogowski coil signal conditioning circuit according to claim 1, wherein: The reference voltage power supply circuit module includes an LC filter unit, a voltage regulator reference unit, a voltage division unit, a capacitor filter unit, a voltage follower unit, and an RC filter unit connected in series in sequence. The LC filter unit is connected to the input first voltage, and the RC filter unit outputs a second voltage, that is, the reference voltage, and the first voltage is higher than the second voltage.

9. The Rogowski coil signal conditioning circuit according to claim 8, wherein: The LC filter unit includes a filter inductor FB1 and a filter capacitor C53 connected in series; the voltage regulator reference unit includes a three-terminal reference chip U9, whose Vin terminal is connected to the middle node between the filter inductor FB1 and the filter capacitor C53, and a capacitor C20 is connected between its Vout terminal and the GND terminal, and its GND terminal is grounded; the voltage division unit includes a voltage division resistor R125 and a voltage division resistor R124 connected in series. The first end of the voltage division resistor R125 is connected to the Vout terminal of the three-terminal reference chip U9, and the second end of the voltage division resistor R124 is grounded; the capacitor filter unit includes a filter capacitor C113, and both ends of it are respectively connected to the middle node between the voltage division resistor R125 and the voltage division resistor R124 and the ground; the voltage follower unit includes an operational amplifier U16, whose non-inverting input terminal is connected to one end of the filter capacitor C113, and its inverting input terminal is connected to its output terminal; the LC filter unit includes a resistor R126 and a filter capacitor C110 connected in series.

10. A circuit breaker, comprising: An electronic tripping unit, the electronic tripping unit includes a microprocessor, and the microprocessor has an AD sampling port. It is characterized in that it further includes: a Rogowski coil and a Rogowski coil signal conditioning circuit connected to the Rogowski coil, and the Rogowski coil signal conditioning circuit is the Rogowski coil signal conditioning circuit according to any one of claims 1-9.

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