CN215493303U

CN215493303U - Three-electrode dissolved oxygen sensor conditioning circuit

Info

Publication number: CN215493303U
Application number: CN202122290803.3U
Authority: CN
Inventors: 褚力; 夏小娇; 王宏庆; 胡俊; 杨祖毛; 傅晟伟; 邱添
Original assignee: Nuclear Power Institute of China
Current assignee: Nuclear Power Institute of China
Priority date: 2021-09-22
Filing date: 2021-09-22
Publication date: 2022-01-11
Anticipated expiration: 2031-09-22

Abstract

The utility model discloses a three-electrode dissolved oxygen sensor conditioning circuit, which relates to the technical field of dissolved oxygen concentration monitoring, and adopts the technical scheme that: the circuit comprises a power supply circuit, a detection circuit and two driving circuits; the power circuit is powered by an external power supply; the positive ends of the two driving circuits are connected with the anode of the dissolved oxygen sensor, the negative end of one driving circuit is connected with the protective electrode of the dissolved oxygen sensor, and the negative end of the other driving circuit is connected with the signal ground in the detection circuit; the detection circuit is connected with the cathode of the dissolved oxygen sensor. The utility model not only can realize the stable driving and weak current signal detection of the three-electrode dissolved oxygen sensor, but also realizes the remote separation of the conditioning circuit and the sensor, and is suitable for the online monitoring of the dissolved oxygen concentration under the complex working conditions of irradiation, high temperature, high pressure and the like.

Description

Three-electrode dissolved oxygen sensor conditioning circuit

Technical Field

The utility model relates to the technical field of dissolved oxygen concentration monitoring, in particular to a three-electrode dissolved oxygen sensor conditioning circuit.

Background

Dissolved oxygen is an important water quality parameter of a primary circuit coolant of a nuclear reactor, and the concentration of the dissolved oxygen in the coolant is directly related to material corrosion of a primary circuit system and migration and deposition of corrosion products, and further related to the radioactive dose of the primary circuit system and the operation safety of the reactor. The oxygen content in the pressurized water reactor coolant should not exceed 0.1mg/L, and therefore, monitoring the dissolved oxygen concentration in the coolant is of great importance to the structural integrity of the primary loop system and the safety of the reactor system.

The dissolved oxygen sensor based on the electrochemical principle adopts a three-electrode structure, comprises an anode, a cathode and a protective electrode, needs to provide a driving voltage signal externally to maintain the electrochemical measurement state, and can not be directly transmitted to a secondary instrument or a measurement and control system for data acquisition and result analysis and needs to be conditioned because a current signal generated by the electrochemical reaction is extremely weak. At present, no conditioning circuit suitable for a three-electrode electrochemical dissolved oxygen sensor exists, the requirement of monitoring the dissolved oxygen concentration in a wide range and high precision can be met, and the remote separation from the sensor can be realized. Therefore, a three-electrode dissolved oxygen sensor conditioning circuit needs to be customized.

In the prior art, chinese patent publication No. CN102520031A discloses a circuit for detecting dissolved oxygen in water, which includes a detection amplifier circuit and a power supply circuit, and the circuit for detecting dissolved oxygen described in this patent is suitable for a two-electrode type dissolved oxygen sensor, which has certain limitations on performance indexes such as the measurement accuracy of dissolved oxygen concentration and the detection lower limit, and generally cannot meet the detection requirement of ppb level dissolved oxygen concentration. In addition, the patent cannot realize the remote separation of the conditioning circuit and the sensor, and cannot be applied to the monitoring of the concentration of dissolved oxygen in the coolant of the nuclear reactor.

Therefore, how to design a three-electrode dissolved oxygen sensor conditioning circuit is a problem which is urgently needed to be solved at present.

SUMMERY OF THE UTILITY MODEL

In order to overcome the defects in the prior art, the utility model aims to provide a conditioning circuit of a three-electrode dissolved oxygen sensor, which not only can realize stable driving and weak current signal detection of the three-electrode dissolved oxygen sensor, but also realizes the remote separation of the conditioning circuit and the sensor, and is suitable for online monitoring of the concentration of dissolved oxygen under complex working conditions of irradiation, high temperature, high pressure and the like.

The technical purpose of the utility model is realized by the following technical scheme: a conditioning circuit of a three-electrode dissolved oxygen sensor comprises a power circuit, a detection circuit and two driving circuits;

the power circuit is powered by an external power supply;

the positive ends of the two driving circuits are connected with the anode of the dissolved oxygen sensor, the negative end of one driving circuit is connected with the protective electrode of the dissolved oxygen sensor, and the negative end of the other driving circuit is connected with the signal ground in the detection circuit; the two driving circuits can independently output two paths of driving voltage signals for driving the dissolved oxygen sensor to work in a measuring state;

the detection circuit is connected with the cathode of the dissolved oxygen sensor; and the detection circuit is used for converting, amplifying, filtering and impedance transforming the cathode current generated by the electrochemical reaction of the dissolved oxygen sensor and outputting a voltage signal matched with the acquisition end of a secondary instrument or a measurement and control system.

Further, the power circuit inputs +24V direct current voltage from an external power supply and outputs +/-10.2V and +1.2V direct current voltage; the +/-10.2V direct-current voltage supplies power for operational amplifiers in the driving circuit and the detection circuit; the +1.2V DC voltage provides the driving original signals for the two driving circuits.

Further, the power supply circuit comprises a fuse F1, a TVS tube D1, a voltage-stabilizing diode D2, a diode D3, a diode D4, a diode D5, a DC-DC converter U1, a voltage stabilizer U2, a voltage stabilizer U3, a power supply chip U4, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10, a capacitor C11, a capacitor C12, a capacitor C13, a capacitor C14, a capacitor C15 and a connection terminal J1;

a pin 1 of the connecting terminal J1 is connected with one end of the fuse F1 and the positive end of an external +24V power supply, and a pin 2 is grounded; the other end of the fuse is connected with the positive end of a diode D3; the other end of the diode D3 is connected with a pin 1 of the DC-DC converter U1; the 2 pin of the DC-DC converter U1 is grounded; the TVS tube D1, the voltage stabilizing diode D2, the capacitor C1 and the capacitor C2 are connected in parallel between the positive end and the negative end of a +24V power supply; the

pins

4, 5 and 6 of the DC-DC converter U1 are respectively connected with one end of an inductor L1, an inductor L2 and one end of an inductor L3; the other end of the inductor L1 is connected with a pin 1 and a pin 3 of the voltage stabilizer U2 and the negative end of the diode D4, the other end of the inductor L2 is grounded, and the other end of the inductor L3 is connected with a pin 5 of the voltage stabilizer U3 and the positive end of the diode D5; one end of the resistor R3 is connected with the pin 4 of the voltage stabilizer U2, and the other end is connected with the pin 5 of the voltage stabilizer U2, the negative end of the diode D4 and one end of the resistor R5; the other end of the resistor R5 outputs +10.2V voltage; one end of the resistor R4 is connected with a pin 3 of the voltage stabilizer U3, and the other end of the resistor R4 is connected with a pin 4 of the voltage stabilizer U3, the positive end of the diode D5 and one end of the resistor R6; the other end of the resistor R6 outputs-10.2V voltage; the capacitor C3 and the capacitor C5 are connected in parallel between the input end of the voltage stabilizer U2 and the ground; the capacitor C4 and the capacitor C6 are connected in parallel between the input end of the voltage stabilizer U3 and the ground; the resistor R1, the capacitor C7, the capacitor C9 and the capacitor C11 are connected between +10.2V and the ground in parallel; the resistor R2, the capacitor C8, the capacitor C10 and the capacitor C12 are connected between-10.2V and the ground in parallel; the 8 pin of the power supply chip U4 is connected with +10.2V, the 4 pin is grounded, and the 1 pin outputs +1.2V voltage; the capacitor C13 and the capacitor C14 are connected between the pin 8 of the power supply chip U4 and the ground in parallel; the capacitor C15 is connected in parallel between pin 1 of the power chip U4 and ground.

Furthermore, the two driving circuits divide the voltage of the input +1.2V driving original signal, the voltage division ratio is respectively regulated by the two slide rheostats, and the voltage signals in the range of 0.4V-0.9V can be independently output; the voltage signals after voltage division are respectively output two paths of driving voltage signals by a voltage follower.

Further, the driving circuit comprises an operational amplifier U5, a slide rheostat RJ1, a potentiometer RP1, a voltage stabilizing diode D6, a resistor R7, a resistor R8, a resistor R9, a BNC connector J2;

one end of the resistor R7 is connected with +1.2V, and the other end is connected with the pin 3 of the slide rheostat RJ1 and the negative end of the voltage stabilizing diode D6; a pin 1 of the slide rheostat RJ1 is connected with one end of the R8 and a pin 3 of the operational amplifier U5; the other end of the resistor R8 and the positive end of the voltage stabilizing diode D6 are both grounded; the pin 7 of the operational amplifier U5 is connected with +10.2V, the pin 4 is connected with-10.2V, and the pin 2 is connected with the pin 6 and one end of the resistor R9; the other end of the resistor R9 is connected with pin 1 of a BNC joint J2, and outputs a driving voltage signal of the dissolved oxygen sensor to the anode of the dissolved oxygen sensor; the 2 pin of the BNC joint J2 is connected with the protective electrode of the dissolved oxygen sensor and grounded;

pins

1 and 3 of the potentiometer RP1 are respectively connected with

pins

1 and 8 of the operational amplifier U5; the capacitor C16 and the capacitor C17 are connected between +10.2V and the ground in parallel; the capacitor C18 and the capacitor C19 are connected in parallel between-10.2V and ground.

Further, the detection circuit includes an I/V converter, a filter, and a voltage follower.

Further, the I/V converter is constructed by an operational amplifier ADA4627 and a precision resistor, and is used for converting a cathode current signal of the dissolved oxygen sensor into a voltage signal and amplifying the voltage signal.

Further, the filter is a second-order Butterworth low-pass filter, and is constructed by an operational amplifier OPA2277 and 2 sets of resistors and capacitors, and is used for filtering the voltage signal output by the I/V converter.

Further, the voltage follower is constructed by an operational amplifier ADA4627 and is used for reducing the output impedance of the dissolved oxygen sensor conditioning circuit and outputting a voltage signal which is related to the concentration of the dissolved oxygen and can be directly collected by the A/D converter.

Further, the detection circuit comprises an operational amplifier U7, an operational amplifier U8, an operational amplifier U9, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a capacitor C24, a capacitor C25 and a BNC joint J4;

a pin 1 of the BNC connector J4 is connected with the cathode of the dissolved oxygen sensor, a pin 2 of the operational amplifier U7 and one end of the resistor R13, and a pin 2 is grounded; the other end of the resistor R13 is connected with a pin 6 of the operational amplifier U7 and one end of the resistor R14; the other end of the resistor R14 is connected with one ends of the resistor R15, the resistor R16 and the capacitor C24; the other end of the capacitor C24 is grounded; the other end of the resistor R16 is connected with one end of the capacitor C25 and the pin 2 of the operational amplifier U8; the other end of the capacitor C25 is connected with the other end of the resistor R15, a pin 1 of the operational amplifier U8 and a pin 3 of the operational amplifier U9; the pin 2 of the operational amplifier U9 is connected with the pin 6 and the pin 1 of the connecting terminal J5; the 2 pin of the connection terminal J5 is grounded, and the 1 pin outputs a voltage signal which is related to the concentration of dissolved oxygen and can be directly collected by the A/D converter.

Compared with the prior art, the utility model has the following beneficial effects:

1. the utility model can realize the stable driving of the double working loops of the three-electrode dissolved oxygen sensor, so that the sensor works in an electrochemical measurement state;

2. the utility model can convert, amplify, filter and impedance transform the cathode current of the three-electrode dissolved oxygen sensor to obtain stable voltage signals which are related to the dissolved oxygen concentration and are matched with the input characteristics of the data acquisition end of the secondary instrument or the measurement and control system, thereby facilitating data acquisition and result analysis;

3. the utility model realizes the remote separation from the dissolved oxygen sensor, and is suitable for the online monitoring of the dissolved oxygen concentration under complex working conditions of irradiation, high temperature, high pressure and the like;

4. the utility model adopts a modular design, has small volume and light weight, and is convenient for installation, disassembly, maintenance and overhaul.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the utility model and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the utility model and together with the description serve to explain the principles of the utility model. In the drawings:

FIG. 1 is a schematic diagram of operation in an embodiment of the present invention;

FIG. 2 is a schematic diagram of a power supply circuit in an embodiment of the utility model;

FIG. 3 is a schematic diagram of a drive circuit in an embodiment of the utility model;

fig. 4 is a schematic diagram of a detection circuit in an embodiment of the utility model.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly or indirectly connected to the other element.

It will be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, as used herein, refer to an orientation or positional relationship indicated in the drawings that is solely for the purpose of facilitating the description and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and is therefore not to be construed as limiting the utility model.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

Example 1: a conditioning circuit of a three-electrode dissolved oxygen sensor is shown in figure 1 and comprises a power supply circuit, a detection circuit and two driving circuits. The power circuit is powered by an external power source. The positive ends of the two driving circuits are connected with the anode of the dissolved oxygen sensor, the negative end of one driving circuit is connected with the protective electrode of the dissolved oxygen sensor, and the negative end of the other driving circuit is connected with the signal ground in the detection circuit; the two driving circuits can independently output two paths of driving voltage signals for driving the dissolved oxygen sensor to work in a measuring state. The detection circuit is connected with the cathode of the dissolved oxygen sensor; and the detection circuit is used for converting, amplifying, filtering and impedance transforming the cathode current generated by the electrochemical reaction of the dissolved oxygen sensor and outputting a voltage signal matched with the acquisition end of a secondary instrument or a measurement and control system.

Example 2: power supply circuit

As shown in fig. 1 and fig. 2, the power circuit inputs +24V dc voltage from an external power source, and outputs ± 10.2V and +1.2V dc voltage; the +/-10.2V direct-current voltage supplies power for operational amplifiers in the driving circuit and the detection circuit; the +1.2V DC voltage provides the driving original signals for the two driving circuits.

As shown in fig. 2, the power supply circuit includes a fuse F1, a TVS transistor D1, a zener diode D2, a diode D3, a diode D4, a diode D5, a DC-DC converter U1, a regulator U2, a regulator U3, a power chip U4, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10, a capacitor C11, a capacitor C12, a capacitor C13, a capacitor C14, a capacitor C15, and a connection terminal J1.

pins

Example 3: driving circuit

As shown in fig. 1 and fig. 3, the two driving circuits divide the voltage of the input +1.2V driving original signal, the voltage division ratio is respectively adjusted by the two sliding varistors, and the voltage signals in the range of 0.4V to 0.9V can be independently output; the voltage signals after voltage division are respectively output two paths of driving voltage signals by a voltage follower.

As shown in fig. 3, the driving circuit includes an operational amplifier U5, a sliding resistor RJ1, a potentiometer RP1, a zener diode D6, a resistor R7, a resistor R8, a resistor R9, and a BNC connector J2.

pins

1 and 3 of the potentiometer RP1 are respectively connected with

pins

Example 4: detection circuit

As shown in fig. 1 and 4, the detection circuit includes an I/V converter, a filter, and a voltage follower. The I/V converter is constructed by an operational amplifier ADA4627 and a precision resistor, and is used for converting a cathode current signal of the dissolved oxygen sensor into a voltage signal and amplifying the voltage signal. The filter is a second-order Butterworth low-pass filter and is constructed by an operational amplifier OPA2277 and 2 groups of resistors and capacitors and used for filtering the voltage signal output by the I/V converter. The voltage follower is constructed by an operational amplifier ADA4627 and is used for reducing the output impedance of the dissolved oxygen sensor conditioning circuit and outputting a voltage signal which is related to the concentration of the dissolved oxygen and can be directly collected by the A/D converter.

As shown in fig. 4, the detection circuit includes an operational amplifier U7, an operational amplifier U8, an operational amplifier U9, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a capacitor C24, a capacitor C25, and a BNC junction J4.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A conditioning circuit of a three-electrode dissolved oxygen sensor is characterized by comprising a power supply circuit, a detection circuit and two driving circuits;

the power circuit is powered by an external power supply;

2. The conditioning circuit of claim 1, wherein the power circuit inputs +24V dc voltage from an external power source and outputs ± 10.2V and +1.2V dc voltage; the +/-10.2V direct-current voltage supplies power for operational amplifiers in the driving circuit and the detection circuit; the +1.2V DC voltage provides the driving original signals for the two driving circuits.

3. The conditioning circuit of the three-electrode dissolved oxygen sensor of claim 1, wherein the power supply circuit comprises a fuse F1, a TVS tube D1, a voltage-stabilizing diode D2, a diode D3, a diode D4, a diode D5, a DC-DC converter U1, a voltage stabilizer U2, a voltage stabilizer U3, a power chip U4, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10, a capacitor C11, a capacitor C12, a capacitor C13, a capacitor C14, a capacitor C15 and a J1;

a pin 1 of the connecting terminal J1 is connected with one end of the fuse F1 and the positive end of an external +24V power supply, and a pin 2 is grounded; the other end of the fuse is connected with the positive end of a diode D3; the other end of the diode D3 is connected with a pin 1 of the DC-DC converter U1; the 2 pin of the DC-DC converter U1 is grounded; the TVS tube D1, the voltage stabilizing diode D2, the capacitor C1 and the capacitor C2 are connected in parallel between the positive end and the negative end of a +24V power supply; the pins 4, 5 and 6 of the DC-DC converter U1 are respectively connected with one end of an inductor L1, an inductor L2 and one end of an inductor L3; the other end of the inductor L1 is connected with a pin 1 and a pin 3 of the voltage stabilizer U2 and the negative end of the diode D4, the other end of the inductor L2 is grounded, and the other end of the inductor L3 is connected with a pin 5 of the voltage stabilizer U3 and the positive end of the diode D5; one end of the resistor R3 is connected with the pin 4 of the voltage stabilizer U2, and the other end is connected with the pin 5 of the voltage stabilizer U2, the negative end of the diode D4 and one end of the resistor R5; the other end of the resistor R5 outputs +10.2V voltage; one end of the resistor R4 is connected with a pin 3 of the voltage stabilizer U3, and the other end of the resistor R4 is connected with a pin 4 of the voltage stabilizer U3, the positive end of the diode D5 and one end of the resistor R6; the other end of the resistor R6 outputs-10.2V voltage; the capacitor C3 and the capacitor C5 are connected in parallel between the input end of the voltage stabilizer U2 and the ground; the capacitor C4 and the capacitor C6 are connected in parallel between the input end of the voltage stabilizer U3 and the ground; the resistor R1, the capacitor C7, the capacitor C9 and the capacitor C11 are connected between +10.2V and the ground in parallel; the resistor R2, the capacitor C8, the capacitor C10 and the capacitor C12 are connected between-10.2V and the ground in parallel; the 8 pin of the power supply chip U4 is connected with +10.2V, the 4 pin is grounded, and the 1 pin outputs +1.2V voltage; the capacitor C13 and the capacitor C14 are connected between the pin 8 of the power supply chip U4 and the ground in parallel; the capacitor C15 is connected in parallel between pin 1 of the power chip U4 and ground.

4. The conditioning circuit of a three-electrode dissolved oxygen sensor as claimed in claim 1, wherein the two driving circuits divide the input +1.2V driving original signal, the dividing ratio is respectively adjusted by the two slide rheostats, and the two driving circuits can independently output a voltage signal in the range of 0.4V to 0.9V; the voltage signals after voltage division are respectively output two paths of driving voltage signals by a voltage follower.

5. The conditioning circuit of claim 1, wherein the driving circuit comprises an operational amplifier U5, a slide rheostat RJ1, a potentiometer RP1, a voltage regulator diode D6, a resistor R7, a resistor R8, a resistor R9, a BNC connector J2;

one end of the resistor R7 is connected with +1.2V, and the other end is connected with the pin 3 of the slide rheostat RJ1 and the negative end of the voltage stabilizing diode D6; a pin 1 of the slide rheostat RJ1 is connected with one end of the R8 and a pin 3 of the operational amplifier U5; the other end of the resistor R8 and the positive end of the voltage stabilizing diode D6 are both grounded; the pin 7 of the operational amplifier U5 is connected with +10.2V, the pin 4 is connected with-10.2V, and the pin 2 is connected with the pin 6 and one end of the resistor R9; the other end of the resistor R9 is connected with pin 1 of a BNC joint J2, and outputs a driving voltage signal of the dissolved oxygen sensor to the anode of the dissolved oxygen sensor; the 2 pin of the BNC joint J2 is connected with the protective electrode of the dissolved oxygen sensor and grounded; pins 1 and 3 of the potentiometer RP1 are respectively connected with pins 1 and 8 of the operational amplifier U5; the capacitor C16 and the capacitor C17 are connected between +10.2V and the ground in parallel; the capacitor C18 and the capacitor C19 are connected in parallel between-10.2V and ground.

6. The conditioning circuit of claim 1 wherein the detection circuit comprises an I/V converter, a filter, and a voltage follower.

7. The conditioning circuit of claim 6, wherein the I/V converter is constructed by an operational amplifier ADA4627 and a precision resistor, and is used for converting the cathode current signal of the dissolved oxygen sensor into a voltage signal and amplifying the voltage signal.

8. The conditioning circuit for a three-electrode dissolved oxygen sensor of claim 6, wherein the filter is a second-order Butterworth low-pass filter constructed by an operational amplifier OPA2277 and 2 sets of resistors and capacitors for filtering the voltage signal output by the I/V converter.

9. The conditioning circuit of claim 6, wherein the voltage follower is constructed by an operational amplifier ADA4627, and is used for reducing the output impedance of the conditioning circuit of the dissolved oxygen sensor and outputting a voltage signal related to the concentration of dissolved oxygen and directly collected by the A/D converter.

10. The conditioning circuit of claim 1, wherein the detection circuit comprises an operational amplifier U7, an operational amplifier U8, an operational amplifier U9, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a capacitor C24, a capacitor C25, a BNC connector J4;