Radiation resistant integrated valve position transmitter

Abstract

The application discloses a kind of radiation-resistant integrated valve position transmitter, belong to the field of transmitter design, including sampling resistance, voltage stabilizing circuit with temperature compensation, sensor power supply circuit, zero adjustment circuit, multistage amplification circuit, range adjustment circuit and constant current source circuit with temperature compensation.Sampling resistance is connected in series between external DC power supply and voltage stabilizing circuit;Voltage stabilizing circuit output end is as internal power bus for each circuit power supply.Sensor power supply circuit uses potentiometer sampling valve opening degree signal, and multistage amplification circuit is converted into current signal output after signal is amplified step by step.The first amplification circuit is equipped with JFET differential pair and first wilson mirror current source, and the valve position transmitter is also provided with second wilson mirror current source to provide bias current for each stage of amplification circuit.The application has excellent radiation resistance and high-precision temperature stability, high output precision, strong anti-radiation ability, and at the same time adopts integrated design, compact structure, high stability.

Description

Technical Field

[0001] This invention relates to the field of transmitter design, and more particularly to a radiation-resistant integrated valve position transmitter. Background Technology

[0002] Valve position transmitters are important instruments in industrial control systems used to detect the valve opening position and convert it into a standard electrical signal output. They are widely used in industrial process control systems in fields such as nuclear power, petroleum, and chemical engineering to provide feedback on the actual working position of valves. A typical valve position transmitter mainly consists of a position sampling module, a signal conditioning module, an analog-to-digital converter (ADC), a microcontroller unit (MCU), and an output module. Its basic working process is as follows: the position sampling module acquires the potential signal corresponding to the valve's rotating shaft, which is then converted into a collectable voltage signal by the signal conditioning module. This voltage signal is then converted into a digital signal by the ADC and transmitted to the MCU. After calibration, the MCU outputs a standard 4-20mA current signal through the output module, corresponding to a valve opening of 0-100%.

[0003] Valve position transmitters used in nuclear power plant environments require characteristics such as radiation resistance, immunity to temperature fluctuations, and high accuracy. Current conventional valve position transmitter circuit designs cannot operate stably under the high radiation and temperature fluctuation conditions of nuclear power environments for extended periods, easily leading to parameter drift and functional failures. This makes it difficult to meet the long-term requirements of lifespan and signal accuracy in nuclear power plant applications. Specifically, the following significant drawbacks exist in their application: 1. Insufficient radiation resistance. Existing valve position transmitters consist of a position sampling module, a signal conditioning module, an analog-to-digital conversion module, a microcontroller unit, and an output module. Their complex structure and numerous components make them more susceptible to parameter drift and functional failure under the high radiation environment of nuclear power plants. Their long-term stability is also worse, failing to meet the accuracy requirements for long-term stable operation of valve position transmitters in nuclear power plants.

[0004] 2. Poor temperature adaptability. Existing conventional valve position transmitters have poor temperature adaptability. In the operating environment of nuclear power plants where temperatures fluctuate easily, the temperature drift coefficient of circuit components is large. Temperature changes will cause circuit parameters to drift, further aggravating the error of the output signal and reducing the reliability of position feedback.

[0005] 3. Weak electromagnetic interference resistance. Most existing valve position transmitters are of a split design, with the sampling module and signal processing circuitry installed separately. These require long leads to transmit analog signals. In the complex electromagnetic environment of nuclear power plants, long leads are more prone to introducing electromagnetic interference, leading to decreased signal stability. Furthermore, the split structure increases the workload of on-site installation and wiring, introduces more potential points of failure, and complicates subsequent maintenance, failing to meet the requirements of nuclear power plant sites for equipment reliability and ease of installation.

[0006] In summary, the existing technology lacks an integrated valve position transmitter that possesses both good radiation resistance and temperature stability and high-precision output requirements to meet the long-term reliability requirements of valve position detection in nuclear power industry sites. Summary of the Invention

[0007] The purpose of this invention is to overcome the technical problems existing in the prior art and to provide a radiation-resistant integrated valve position transmitter.

[0008] The objective of this invention is achieved through the following technical solution: A radiation-resistant integrated valve position transmitter is provided, comprising a sampling resistor, a voltage regulator circuit with temperature compensation, a sensor power supply circuit, a zero-adjustment circuit, a multi-stage amplifier circuit, a range adjustment circuit, and a constant current source circuit with temperature compensation; the multi-stage amplifier circuit includes a first-stage amplifier circuit and at least one subsequent-stage amplifier circuit connected in series. The radiation-resistant integrated valve position transmitter adopts a two-wire system, and the sampling resistor is connected in series between the external DC power supply and the temperature-compensated voltage regulator circuit. The output terminal of the temperature-compensated voltage regulator circuit serves as an internal power bus, and is connected in parallel to the power input terminal of the sensor power supply circuit, the power input terminal of the zero-adjustment circuit, the power input terminal of the multi-stage amplifier circuit, the power input terminal of the range adjustment circuit, and the power input terminal of the temperature-compensated constant current source circuit. The sensor power supply circuit uses a potentiometer as a position sampling element. Its sliding end is synchronously connected to the valve rotation shaft in the valve position transmitter. Its sliding end is also connected to the first differential input terminal of the first-stage amplifier circuit to output a voltage sampling signal that is proportional to the valve opening. The output terminal of the zero-adjustment circuit is connected to the second differential input terminal of the first-stage amplifier circuit. By adjusting the resistance value of the zero-point adjustment potentiometer in the zero-adjustment circuit, the reference voltage of the first-stage amplifier circuit is adjusted, thereby achieving zero-point calibration of the output signal. The first-stage amplifier circuit amplifies the voltage difference between the voltage signals output by the zero-adjustment circuit and the sensor power supply circuit, and then outputs it sequentially to the subsequent amplifier circuit. The voltage signal output by the subsequent amplifier circuit is then output to the range adjustment circuit. The range adjustment circuit converts the amplified voltage signal into a current signal and outputs it, using the current signal on the sampling resistor as the output current signal representing the valve opening. The primary amplifier circuit includes a JFET differential pair and a first Wilson mirror current source connected in sequence, with the first Wilson mirror current source serving as the active load of the JFET differential pair.

[0009] In some embodiments, each stage of the multi-stage amplifier circuit is constructed from non-radiation-hardened discrete components, including transistors, junction field-effect transistors, high-precision metal film resistors, diodes, Zener diodes, and ceramic capacitors.

[0010] In some embodiments, the JFET differential pair includes a first JFET junction field-effect transistor and a second JFET junction field-effect transistor. The gate of the first JFET junction field-effect transistor is connected to the output terminal of the sensor power supply circuit as a first differential input terminal. The gate of the second JFET junction field-effect transistor is connected to the output terminal of the zero-adjustment circuit as a second differential input terminal. The drain of the JFET differential pair is connected to the first Wilson mirror current source. The first Wilson mirror current source includes a first transistor, a second transistor, a third transistor, a first resistor, a second resistor, and a third resistor. The collector of the first transistor is connected to the internal power bus, the base of the first transistor is connected to the drain of the first JFET, and the emitter of the first transistor is connected to the second resistor. The common connection point between the first transistor and the second resistor is connected to the base of the second transistor and the base of the third transistor, respectively. The collector of the third transistor is connected to the drain of the second JFET, and the emitter of the third transistor is connected to the third resistor. The collector of the second transistor is connected to the drain of the first JFET, and the emitter of the second transistor is connected to the first resistor.

[0011] In some embodiments, the valve position transmitter is further provided with: The second Wilson mirror current source has its input terminal connected to the output terminal of the temperature-compensated constant current source circuit, and its output terminal connected to each stage of the amplifier circuit; the second Wilson mirror current source provides bias current to each stage of the amplifier circuit.

[0012] In some embodiments, the constant current source circuit with temperature compensation includes a third JFET junction field-effect transistor, a fourth resistor, a fifth resistor, a first diode, a second diode, a first Zener diode, and a fourth transistor. The source of the third JFET junction field-effect transistor is connected to the input terminal of the fourth resistor, and the output terminal of the fourth resistor is connected to the gate of the third JFET junction field-effect transistor. The anode of the first diode is connected to the common connection point between the fourth resistor and the gate of the third JFET. The first diode, the second diode, and the first Zener diode are connected in series. The base of the fourth transistor is connected to the common connection point between the fourth resistor and the gate of the third JFET. The collector of the fourth transistor is connected to the internal power bus. The emitter of the fourth transistor is connected to the anode of the first Zener diode through the fifth resistor.

[0013] In some embodiments, the first Zener diode is a Zener diode, and the voltage drop changes of the first diode, the second diode, and the first Zener diode cancel each other out when exposed to irradiation.

[0014] In some embodiments, the temperature-compensated voltage regulator circuit includes a fourth JFET, a fifth transistor, a sixth transistor, a seventh transistor, a third diode, a second Zener diode, and a sixth resistor. The source of the fourth JFET is connected to the input of the sixth resistor, the output of the sixth resistor is connected to the gate of the fourth JFET, and the output of the sixth resistor is connected to the collector of the sixth transistor. The base of the sixth transistor is connected to the collector, the emitter of the sixth transistor is connected to the emitter of the seventh transistor, the base of the seventh transistor is connected to the collector, the collector of the seventh transistor is connected to the anode of the third diode, the cathode of the third diode is connected to the cathode of the second Zener diode, and the anode of the second Zener diode is grounded. The output of the sixth resistor is also connected to the base of the fifth transistor, the collector of the fifth transistor is connected to the drain of the fourth JFET, and the emitter of the fifth transistor is connected to other downstream circuitry.

[0015] In some embodiments, the fifth and sixth transistors are of the same type; when the ambient temperature rises, the seventh transistor and the third diode have negative temperature coefficients, and the second Zener diode is an avalanche diode with a positive temperature coefficient, and the voltage drop changes on the seventh transistor, the third diode, and the second Zener diode cancel each other out.

[0016] In some embodiments, the multi-stage amplifier circuit includes a first-stage amplifier circuit, a second-stage amplifier circuit, and a third-stage amplifier circuit, wherein the first-stage amplifier circuit is the primary amplifier circuit, and the open-loop gain formed by the second-stage amplifier circuit and the first-stage amplifier circuit exceeds 100dB; the third-stage amplifier circuit is used for power output.

[0017] In some embodiments, the voltage accuracy fluctuation range of the temperature-compensated voltage regulator circuit output is ≤0.5‰, and the accuracy fluctuation range of the output current signal representing the valve opening on the sampling resistor is ≤0.5%FS.

[0018] It should be further noted that the technical features corresponding to the above-mentioned options and embodiments can be combined or substituted with each other to form new technical solutions without conflict.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention, through a specialized radiation-resistant circuit design, selects electronic components with radiation resistance levels that meet the requirements, and employs a Wilson current mirror structure for the critical amplification circuit. This effectively resists the effects of ionizing radiation present in nuclear industrial sites, prevents radiation-induced component parameter drift, ensures the stability of the circuit's output current, and solves the problem that ordinary valve position transmitters cannot operate reliably for extended periods in nuclear power plant irradiation environments. On the one hand, this invention replaces the integrated circuit solution used in traditional valve position transmitters by using discrete components to build amplification circuits at each stage. The discrete components (transistors, junction field-effect transistors, high-precision metal film resistors, diodes, Zener diodes, and ceramic capacitors, etc.) are selected based on their respective radiation damage thresholds, and the total radiation absorbed dose of a single component is at least 10... 4 -10 5 Gy ensures the overall radiation resistance of the circuit from the component level.

[0020] On the other hand, the first-stage amplifier circuit of this invention adopts a JFET differential pair structure. The JFET gate and source are reverse-biased PN junctions with no gate oxide layer. The normal gate-drain current is in the pA range, and the natural input impedance reaches the GΩ level. It is unaffected by gate oxide irradiation damage. After irradiation, the gate-drain current only increases slightly, and it can still maintain stable amplification performance under high irradiation environment. At the same time, the first-stage amplifier circuit uses a first Wilson mirror current source as the active load of the JFET differential pair, which increases the input impedance of the first-stage amplifier circuit. This is beneficial for the circuit to obtain high open-loop gain and improves the circuit's ability to suppress common-mode interference. The first Wilson mirror current source relies on internal negative feedback to offset the loss caused by base shunt. When irradiation causes the transistor current amplification factor β to decrease, the replication accuracy of the output current and the reference current is almost unaffected, ensuring the stability of the static operating point of the first-stage amplifier circuit.

[0021] Furthermore, this invention also includes a second Wilson mirror current source to provide bias current for each stage of the amplifier circuit. When irradiation causes a drop in transistor β, the second Wilson mirror current source automatically increases the bias current to offset the gain attenuation caused by the drop in β, further stabilizing the static operating point of each stage of the amplifier circuit. Simultaneously, a constant current source circuit with temperature compensation provides a reference current to the second Wilson mirror current source. This temperature-compensated constant current source circuit utilizes the opposite irradiation effects—the decrease in the Zener diode's voltage regulation value under irradiation and the increase in the forward voltage drop of the first and second diodes—to compensate for these effects. This ensures a stable reference current is provided to the second Wilson mirror current source even under irradiation conditions, further stabilizing the bias current output by the second Wilson mirror current source, preventing irradiation-induced shifts in the amplifier circuit's operating point and gain parameters, and ensuring stable output signal accuracy of the amplifier circuit.

[0022] 2. This invention provides a stable operating voltage for the sensor power supply circuit, amplification circuit, and range adjustment circuit through a temperature-compensated voltage regulator circuit. In this voltage regulator circuit, the fourth JFET and the fifth resistor form a voltage-controlled constant current source, and the channel current is unaffected by input voltage fluctuations through a negative feedback closed loop. Simultaneously, by connecting the seventh transistor and the third diode (negative temperature coefficient) in series with the second Zener diode (avalanche diode, positive temperature coefficient), precise parameter design ensures that the positive and negative temperature coefficients cancel each other out, achieving full-temperature compensation of the operating voltage. Specifically, when the input voltage of the temperature-compensated voltage regulator circuit fluctuates within the range of 12-21.6V, the overall voltage accuracy fluctuation is controlled within 0.5‰, ultimately ensuring that the accuracy fluctuation of the output current across the full-scale (FS) temperature range is controlled within 0.5%FS. Compared to ordinary valve position transmitters, this provides higher output accuracy, more accurately reflects the actual valve opening, and provides more reliable opening data for industrial control systems.

[0023] 3. This invention integrates the sensor power supply circuit, zero-adjustment circuit, multi-stage amplification circuit, range adjustment circuit, and constant current source circuit with temperature compensation into a single circuit. The potentiometer in the sensor power supply circuit is directly and synchronously connected to the valve rotation shaft, eliminating the traditional separate structure of the sensor and transmitter circuit in separate valve position transmitters, where signals are transmitted via wires. The integrated design eliminates the external signal connection lines required for separate structures, reducing external wiring links. This lowers the risk of wiring errors and external signal interference, while also reducing the overall installation size, making it suitable for the compact installation space of nuclear power plants. Furthermore, the integrated structure further reduces the risk of external connection failure under irradiation environments, better meeting the high reliability requirements of high-irradiation scenarios.

[0024] 4. This invention employs a two-wire design, with power supply and signal acquisition sharing a single circuit. A sampling resistor is connected in series between the external DC power supply and the voltage regulator circuit. The current signal across the sampling resistor serves as both the supply current and the output signal current representing the valve opening. Through the high input impedance JFET differential pair design of the first-stage amplifier circuit, optimized adjustment of the static operating points of each stage amplifier circuit, and the low-power biasing method of the second Wilson mirror current source, the overall static operating current of the transmitter is ensured to be controlled below 4mA, thus achieving a complete output range of 4-20mA under two-wire power supply conditions. Compared to traditional three-wire valve position transmitters, which require a built-in independent power supply regulator circuit, have numerous components, generate significant heat, and have a short lifespan in high-temperature environments, this invention's low-power design significantly improves the equipment's operating life and reliability in the high-temperature environment of nuclear power plants. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of a radiation-resistant integrated valve position transmitter according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the first-stage amplifier circuit structure shown in an embodiment of the present invention; Figure 3 This is a schematic diagram showing the connection between the second Wilson mirror current source and the amplifier circuit in an embodiment of the present invention; Figure 4 This is a schematic diagram of a constant current source circuit with temperature compensation, as shown in an embodiment of the present invention. Figure 5 This is a schematic diagram of a temperature-compensated voltage regulator circuit structure shown in an embodiment of the present invention. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that the defects in the solutions in the prior art are all the results of the inventors' practice and careful research. Therefore, the discovery process of the above problems and the solutions proposed by the embodiments of this application in the following text should be the inventors' contributions to this application in the process of invention and creation, and should not be understood as technical content known to those skilled in the art.

[0028] In view of the technical problems pointed out in the background art, the present invention provides the following embodiments: In one exemplary embodiment, a radiation-resistant integrated valve position transmitter is provided, taking a three-stage amplifier circuit as an example, such as... Figure 1 As shown, it includes a sampling resistor R1, a voltage regulator circuit with temperature compensation, a sensor power supply circuit, a zeroing circuit, a first-stage amplifier circuit, a second-stage amplifier circuit, a third-stage amplifier circuit, a range adjustment circuit, and a constant current source circuit with temperature compensation.

[0029] This radiation-resistant integrated valve position transmitter is a two-wire system powered by a 24V DC source. The 24V DC source flows through the sampling resistor R1 and then connects to a temperature-compensated voltage regulator circuit, which powers subsequent circuits. The sensor power supply circuit uses a potentiometer as the position sampling element. The potentiometer's sliding end is synchronously connected to the valve's rotation shaft within the valve position transmitter. The potentiometer's sliding end is also connected to the first differential input of the first-stage amplifier circuit to output a voltage sampling signal proportional to the valve opening.

[0030] Simultaneously, the output terminal of the zero-adjustment circuit is connected to the second differential input terminal of the first-stage amplifier circuit. By adjusting the resistance value of the zero-point adjustment potentiometer in the zero-adjustment circuit, the reference voltage of the first-stage amplifier circuit can be adjusted to achieve zero-point calibration of the output signal. The first-stage amplifier circuit amplifies the voltage difference between the voltage signals received from the zero-adjustment circuit and the sensor power supply circuit, and then outputs it sequentially to the second-stage amplifier circuit and the third-stage amplifier circuit. The voltage signal output by the third-stage amplifier circuit is directly sent to the subsequent range adjustment circuit. The range adjustment circuit converts the amplified voltage signal into a current signal for output. Finally, the current signal on the sampling resistor R1 is used as the output current signal representing the valve opening degree. This valve position transmitter is powered by DC24V, with an internal load of less than or equal to 600Ω. The output current signal is 4-20mA, corresponding to the valve opening degree of 0-100% (different valves have different opening angles; in this embodiment, the valve opening angle is optionally 0-90°, corresponding to the valve opening degree of 0-100%).

[0031] The first, second, and third stage amplifier circuits are constructed using non-radiation-hardened discrete components. Compared to the integrated circuit design used in traditional valve position transmitters, the discrete component amplifier circuits significantly improve the radiation resistance of this integrated valve position transmitter. The discrete components include transistors, junction field-effect transistors, high-precision metal film resistors, diodes, Zener diodes, and ceramic capacitors. Each component is selected based on its own radiation damage threshold, ensuring that the total radiation absorbed by a single component reaches at least 10 ppm. 4 -10 5 The valve position transmitter can withstand a cumulative radiation dose of 62.5 KGy under an irradiation dose rate of 2.5 KGy / h.

[0032] Please see Figure 2 The first-stage amplifier circuit includes a JFET differential pair (a first JFET Q1 and a second JFET Q2). The first JFET Q1 and the second JFET Q2 are connected to the sensor power supply circuit and the zero-adjustment circuit, respectively, to receive the input voltage signal. Specifically, the gate of the first JFET Q1 serves as the first differential input terminal, connected to the output terminal of the sensor power supply circuit, and the gate of the second JFET Q2 serves as the second differential input terminal, connected to the output terminal of the zero-adjustment circuit. The JFET gate and source are reverse-biased PN junctions with no gate oxide layer. Under normal conditions, the gate leakage current is in the pA range, and the natural input impedance reaches the GΩ level, significantly higher than that of conventional transistor differential circuits. Furthermore, the JFET is unaffected by gate oxide irradiation damage; after irradiation, the gate leakage current only increases slightly, maintaining high input impedance for a long period. This ensures stable amplification performance even under high irradiation conditions, reducing irradiation-induced gain drift.

[0033] Furthermore, the first-stage amplifier circuit also includes a first Wilson mirror current source, and the JFET differential pair is connected to this first Wilson mirror current source, which serves as the active load of the JFET differential pair. Figure 2 As shown, the first Wilson mirror current source includes a first transistor Q3, a second transistor Q4, a third transistor Q5, a first resistor R2, a second resistor R3, and a third resistor R4. The collector of the first transistor Q3 is connected to the internal power bus, the base of the first transistor Q3 is connected to the drain of the first JFET junction field-effect transistor Q1, and the emitter of the first transistor Q3 is connected to the second resistor R3. The common connection point between the first transistor Q3 and the second resistor R3 is connected to the base of the second transistor Q4 and the base of the third transistor Q5, respectively. The collector of the third transistor Q5 is connected to the drain of the second JFET junction field-effect transistor Q2, and the emitter of the third transistor Q5 is connected to the third resistor R4. The collector of the second transistor Q4 is connected to the drain of the first JFET junction field-effect transistor Q1, and the emitter of the second transistor Q4 is connected to the first resistor R2.

[0034] It should be noted that the current mirror of a traditional basic bipolar junction transistor (BJT) is affected by the base shunt of the transistor. A portion of the reference current is diverted to the bases of both transistors, resulting in an output current that is naturally smaller than the reference current. The replication error is determined by the transistor's current amplification factor β; the smaller the current amplification factor β, the greater the base shunt loss and the worse the replication accuracy. Irradiation causes the transistor's current amplification factor β to decrease. The first Wilson current mirror source uses internal negative feedback to offset the losses caused by the base shunt. The effect of the base shunt is compensated by the feedback loop, significantly reducing the impact of the current amplification factor β on current replication. Under the device's nominal parameters, the output current and reference current are almost equal, significantly improving the current mirror matching accuracy, reducing mirror current fluctuations, and maintaining a stable quiescent operating point for the first-stage amplifier circuit. Simultaneously, as an active load for the JFET differential pair, the first Wilson current mirror source enables efficient conversion of differential dual-ended signals to single-ended signals through precise mirror current, reducing input stage signal loss and improving the op-amp's common-mode rejection ratio. Under the negative feedback, the equivalent dynamic internal resistance of the output terminal of the first Wilson mirror current source is much higher than that of a normal current mirror, which is a high internal resistance active constant current load. The JFET differential pair uses the Wilson mirror current source as the drain active load. The larger the load resistance, the higher the single-stage voltage gain of the first stage amplifier circuit, which is beneficial for the circuit to obtain high open-loop gain and improve the circuit's ability to suppress common-mode interference. Specifically, in this embodiment, the open-loop gain of the first stage amplifier circuit can still be maintained above 83dB under irradiation.

[0035] Furthermore, the second-stage amplifier circuit receives the voltage signal output from the first-stage amplifier circuit to further amplify the signal. After being exposed to irradiation, the open-loop gain of the second-stage amplifier circuit decreases. Using a high-frequency, high-gain transistor, the open-loop gain of the combined first and second-stage amplifier circuits is approximately 140dB. After irradiation, the amplification factor in the first-stage amplifier circuit remains essentially unchanged, while the open-loop gain of the second-stage amplifier circuit decreases by approximately 20–30dB. Ultimately, the total open-loop gain of the two-stage amplifier circuit still exceeds 100dB. The third-stage amplifier circuit is used for power output, driving the downstream load. The output of the third-stage amplifier circuit is connected to a range adjustment circuit.

[0036] Please see Figure 3 and Figure 4Each stage of the amplifier circuit requires a bias current to operate in the amplification region. This valve position transmitter also has another Wilson mirror current source (second Wilson mirror current source) to provide bias current to each stage of the amplifier circuit. The bias current can be automatically compensated for changes in the transistor current amplification factor β caused by temperature and irradiation. When irradiation causes the transistor current amplification factor β to decrease, the second Wilson mirror current source will automatically increase the bias current to offset the gain attenuation caused by the decrease in the current amplification factor β, further stabilize the static operating point of each stage of the amplifier circuit, maintain the stability of the open-loop gain, reduce the gain drift caused by irradiation, and ensure the stability of the overall amplification performance of the amplifier circuit under high irradiation environment.

[0037] The second Wilson mirror current source is connected to a temperature-compensated constant current source circuit, which provides a reference current for the second Wilson mirror current source. In this embodiment, the temperature-compensated constant current source circuit includes a third JFET junction field-effect transistor Q6, a fourth resistor R5, a fifth resistor R6, a first diode D1, a second diode D2, a first Zener diode D3, and a fourth transistor Q7. The source of the third JFET junction field-effect transistor Q6 is connected to the input terminal of the fourth resistor R5, and the output terminal of the fourth resistor R5 is connected to the gate of the third JFET junction field-effect transistor Q6. The anode of the first diode D1 is connected to the common connection point between the fourth resistor R5 and the gate of the third JFET Q6. The third JFET Q6 and the fourth resistor R5 constitute a voltage-controlled constant current source. The first diode D1, the second diode D2, and the first Zener diode D3 are connected in series. The base of the fourth transistor Q7 is connected to the common connection point between the fourth resistor R5 and the gate of the third JFET Q6. The collector of the fourth transistor Q7 is connected to the internal power bus. The emitter of the fourth transistor Q7 is connected to the anode of the first Zener diode D3 through the fifth resistor R6.

[0038] In this circuit, the first Zener diode D3 is a Zener diode. When exposed to radiation, the voltage drops of the first diode D1 and the second diode D2 increase, while the voltage drop of the first Zener diode D3 decreases. This allows the voltage drop changes of the first diode D1, the second diode D2, and the first Zener diode D3 to cancel each other out, preventing the reference current output by the temperature-compensated constant current source circuit from drifting due to radiation. This ensures the stability of the bias current output by the second Wilson mirror current source, avoiding radiation-induced operating point shift and gain parameter drift in the amplifier circuit, and ensuring the stability of the amplifier circuit's output signal accuracy. This further reduces the probability of device failure under high radiation conditions, ensuring the overall circuit can operate stably for a long time under high radiation environments, meeting the service life requirements of nuclear power plant sites.

[0039] Meanwhile, the gate bias voltage V of the JFET gs Having a negative temperature coefficient, semiconductors exhibit more intense atomic vibrations as temperature increases. This significantly hinders electron flow in the channel, reducing carrier mobility. This impeded electron flow directly leads to a decrease in channel current I. d The current tends to decrease. When the channel current I of the third JFET Q6... d When attempting to reduce the voltage drop V across the fourth resistor R5, R5 It will also decrease accordingly. For N-channel enhancement-mode JFETs, V R5 =-V gs When V R5 As it rises, |V gs |Increases. The characteristic of JFET is |V gs The larger the value, the more severe the channel pinch-off, and the higher the current I. d The smaller the |V, the larger the |V gs The smaller the value, the lower the current I. d The larger the channel current I becomes, the more it increases. This forms a negative feedback loop; as the temperature rises, the channel current I increases. d The attempt to reduce the channel current I is hindered by its own negative feedback mechanism. d It increases. Ultimately, the channel current I... d It will stabilize at an equilibrium point.

[0040] Furthermore, as the temperature rises, the first diode D1, the second diode D2, the first Zener diode D3, and the fourth transistor Q7 have negative temperature coefficients, and the voltage across these devices decreases due to temperature variations. (From the circuit...) Figure 4 It can be seen that V Q7 +V R6 =V D1 +V D2 +V D3 →V R6 =V D1 +V D2 +V D3 -V Q7 When the temperature rises, V R6 =V D1 +ΔV D1 +V D2 +ΔV D2 +V D3 +ΔV D3 -V Q7 -ΔV Q7 =V D1 +V D2 +V D3 -V Q7 +(ΔV) D1 +ΔV D2 +ΔVD3 -ΔV Q7 Therefore, when the ΔV decreases on the fourth transistor Q7, Q7 The magnitude is equal to the voltage drop (ΔV) across the first diode D1, the second diode D2, and the first Zener diode D3. D1 +ΔV D2 +ΔV D3 When temperature compensation is achieved, the voltage across the fifth resistor R6 remains stable, which in turn keeps the reference current supplied by the fourth transistor Q7 to the second Wilson mirror current source stable.

[0041] As one specific implementation, the constant current source circuit with temperature compensation is connected in series: two forward-biased silicon diodes D1 and D2 + a low-voltage Zener diode D3 (V D3 <5.500V, tunneling Zener diode); Besides D1, D2, and D3, the branch also contains other circuit components (resistors / transistors, etc.), therefore: V in =V D1 +V D2 +V D3 +V 其余 V in This represents the total voltage in the series branch.

[0042] Irradiation compensation target: ΔV D1 +ΔV D2 +ΔV D3 =0, the sum of the series voltage drops of the first diode D1, the second diode D2 and the first Zener diode D3 remains unchanged, thus offsetting the irradiation drift.

[0043] Selection of room temperature parameters for devices: 1. D1, D2: Silicon small-signal diodes; single diode forward voltage drop at room temperature: V D1 =V D2 =0.700V, total for both at room temperature: V D1 +V D2 =1.400V; Irradiation law: When a BJT / ordinary PN junction diode is irradiated with γ+ neutrons, its forward voltage drop increases under the same constant current (positive drift); let the voltage drop increment of a single diode under irradiation be ΔV. D1 =+15mV, then: ΔV D1 +ΔV D2 =+30mV=+0.030V; 2. Zener Pipe D3: Low-pressure tunnel through Zener, nominal V D3 <4.700V (<5.500V, pure tunneling breakdown); Low-pressure Zener irradiation characteristics: After irradiation, the tunneling barrier decreases, and the voltage stabilization value decreases (ΔV). D3 (The value is negative). To achieve compensation, ΔV D3 =-(ΔV D1 +ΔV D2 =-30mV =-0.030V; Change in total voltage drop across the three devices: ΔV 总 =ΔV D1 +ΔV D2 +ΔV D3 =+30-30=0mV, the voltage drop of the two diodes is completely offset by the voltage regulation value of the low-voltage Zener diode.

[0044] In summary, the radiation-resistant integrated valve position transmitter's radiation-resistant design, through the selection of separate components with better radiation tolerance and the combination of a compensation circuit designed for radiation drift, significantly improves the overall stability of the valve position transmitter under high radiation environments by addressing multiple dimensions from component selection and circuit structure design to drift compensation. It can operate for extended periods under radiation environments with a maximum total absorbed dose of 62.5 KGy, avoiding parameter drift and functional failure caused by radiation, and meeting the long-term stability requirements for valve position detection in nuclear power plants.

[0045] As a further improvement, this radiation-resistant integrated valve position transmitter has a preset operating temperature of 0-60℃. A temperature-compensated voltage regulator circuit provides a stable operating voltage for the sensor power supply circuit, amplification circuit, and conditioning circuit. By providing a more stable operating voltage, the output reference of the entire circuit system will not deviate significantly with changes in ambient temperature, fundamentally reducing the impact of temperature variations on the accuracy of the output signal. This improves the accuracy of the current signal representing the valve opening, achieving an output current accuracy of ≤±0.5%, meeting the signal accuracy requirements of the temperature-varying environment in nuclear power plants.

[0046] Please see Figure 5The temperature-compensated voltage regulator circuit includes a fourth JFET (junction field-effect transistor) Q8, a fifth transistor Q9, a sixth transistor Q10, a seventh transistor Q11, a third diode D4, a second Zener diode D5, and a sixth resistor R7. The source of the fourth JFET Q8 is connected to the input of the sixth resistor R7, and the output of the sixth resistor R7 is connected to the gate of the fourth JFET Q8. Simultaneously, the output of the sixth resistor R7 is connected to the collector of the sixth transistor Q10, and the base of the sixth transistor Q10 is connected to the collector. The emitter of transistor Q10 is connected to the emitter of transistor Q11, the base of transistor Q11 is connected to the collector, the collector of transistor Q11 is connected to the anode of diode D4, the cathode of diode D4 is connected to the cathode of Zener diode D5, and the anode of Zener diode D5 is grounded. The output of resistor R7 is also connected to the base of transistor Q9, the collector of transistor Q9 is connected to the drain of JFET Q8, and the emitter of transistor Q9 is connected to other downstream circuits.

[0047] It should be noted that under normal conditions where the temperature does not change, please refer to [the relevant documentation / reference]. Figure 5 In the temperature-compensated voltage regulator circuit, the fourth JFET, Q8, is used as a voltage-controlled constant current source. The fourth JFET, Q8, is an N-channel enhancement-mode JFET. The gate bias voltage V is set using the voltage drop across the sixth resistor, R7. gs Thus setting the channel current I d When the channel current I of the fourth JFET junction field-effect transistor Q8 d When attempting to increase the voltage, the voltage drop V across the sixth resistor R7... R7 It will also increase accordingly. For N-channel enhancement-mode JFETs, V R7 =-V gs When V R7 As it rises, |V gs |Increases. The characteristic of JFET is |V gs The larger the value, the more severe the channel pinch-off, and the higher the current I. d The smaller the current, the better. This forms a negative feedback loop. Channel current I d If it tries to increase, it will be suppressed by the voltage drop it generates. Ultimately, the channel current I... d It will stabilize at an equilibrium point: (V) gs It is the pinch-off voltage of the JFET.

[0048] Therefore, the channel current I of the fourth JFET junction field-effect transistor Q8 dUnaffected by input voltage fluctuations in the temperature-compensated voltage regulator circuit, and controlled only by the gate-source bias voltage, the current in the temperature-compensated voltage regulator circuit remains stable, meaning the voltage drop across the seventh transistor Q11, the third diode D4, and the second Zener diode D5 also remains stable.

[0049] When the temperature changes, please refer to Figure 5 Let the voltage on the emitter side of the fifth transistor Q9 be the operating voltage V1 that supplies power to the downstream side, and the voltage V2 at the connection point between the base of the fifth transistor Q9 and the sixth resistor R7. From the circuit principle, we know that: V1 = V2 - V Q9 -V Q9T ; V2=V Q10 +V Q10T +V Q11 +V Q11T +V D4 +V D4T +V D5 +V D5T ; Substituting the formula into the calculation yields: V1 = (V Q10 +V Q10T -V Q9 -V Q9T )+V Q11 +V Q11T +V D4 +V D4T +V D5 +V D5T ; In this temperature-compensated voltage regulator circuit, the fifth transistor Q9 and the sixth transistor Q10 use the same type of transistor, so the voltage parameters of the fifth transistor Q9 and the sixth transistor Q10 can cancel each other out. V1=V Q11 +V Q11T +V D4 +V D4T +V D5 +V D5T ; V Q9 For the voltage drop of the fifth transistor Q9 itself, V Q9T This represents the voltage drop change of transistor Q9 when the temperature changes; the others are similar.

[0050] Meanwhile, as the temperature rises, the seventh transistor Q11 and the third diode D4 exhibit a negative temperature coefficient, V Q11T and V D4T Less than 0. The second Zener diode D5 is an avalanche diode, which has a positive temperature coefficient, V D5T Greater than 0.

[0051] By designing circuit parameters, the total voltage drop change in the negative temperature coefficient region can be made equal in magnitude and opposite in direction to the voltage drop change in the positive temperature coefficient region, i.e., V Q11T +V D4T +V D5T =0, V1=V Q11 +V D4 +V D5 .

[0052] With the channel current in the temperature-compensated voltage regulator circuit remaining constant, the voltage V across the seventh transistor Q11, the third diode D4, and the second Zener diode D5 is... Q11 V D4 and V D5 It also remains unchanged, since V1=V Q11 +V D4 +V D5 Therefore, the operating voltage V1 remains constant. Ultimately, V1 remains constant regardless of temperature changes and voltage fluctuations, achieving temperature compensation for the power supply voltage of the subsequent circuit. This fundamentally suppresses the impact of temperature drift on the accuracy of the output signal, further improving the stability of the operating voltage of the subsequent circuit, thereby reducing current fluctuations and ultimately improving the accuracy of the 4-20mA current output by the valve position transmitter.

[0053] In one specific implementation, the input voltage of the temperature-compensated voltage regulator circuit fluctuates between 12-21.6V. Due to the JFET voltage-controlled constant current source, the sum of the voltage drops across the seventh transistor Q11, the third diode D4, and the second Zener diode D5 remains stable. Specifically, the operating voltage V1 is set to 9.000V, i.e., V... Q11 +V D4 +V D5 =9.000V; the total voltage accuracy fluctuation after temperature change is required to be no more than 0.5‰, with compensation for the ideal relationship ΔV. Q11 +ΔV D4 +ΔV D5 =0; 1. Rated partial pressure at room temperature V Q11 =0.700V, V D4 =0.700V, V D5 =9.0-0.7-0.7=7.600V; 2. Single-°C drift under ideal full compensation Example of project selection control: Q11 transistor: ΔV Q11 =-2.0±0.10mV / ℃ D4 diode: ΔV D4 =-2.0±0.10mV / ℃ D5 (7.600V, avalanche Zener diode): ΔV D5 =+4.0±0.15mV / ℃ 3. Example of voltage after temperature rise ΔT (for example, ΔT = 10℃) Ideal value: V Q11 =0.7 - 0.002 × 10 = 0.680 V, V D4 =0.7 - 0.002 × 10 = 0.680 V, V D5 =7.600 + 0.004 × 10 = 7.640 V, V Q11 +V D4 +V D5 The sum is still equal to 9.000V; after superimposing the maximum tolerance, the total error is only |±0.35mV|×10=3.5mV, and the voltage fluctuation is 3.5mV / 9.000V=0.39‰<0.5‰, which enables the temperature-compensated voltage regulator circuit to achieve temperature compensation while the voltage accuracy fluctuation range does not exceed 0.5‰.

[0054] Meanwhile, because the voltage signal output by the amplifier circuit is affected by the voltage signal output by the sensor power supply circuit, and the voltage signal output by the sensor power supply circuit fluctuates continuously with the valve opening, when the fluctuation amplitude of the voltage signal is not large enough, even slight interference to the circuit will affect the accuracy of the output 4-20mA current. In this invention, the current accuracy is improved by increasing the voltage signal. Specifically, the integrated valve position transmitter is powered by a 24V DC source, the potentiometer in the sensor power supply circuit has a resistance of 500 ohms, and the voltage signal output by the sensor power supply circuit corresponding to the valve position 0-90° is 2-10V.

[0055] Through the above circuit design, at an operating temperature of 0-60℃, the constant current source in the temperature-compensated voltage regulator circuit keeps the current in the circuit stable. The stable operating voltage output by the temperature-compensated voltage regulator circuit keeps the current in the subsequent zero-adjustment circuit and sensor power supply circuit stable. The Wilson mirror current source keeps the current in each stage of the amplifier circuit stable. Ultimately, the current accuracy of the current signal representing the valve opening output by the sampling circuit R1 in this radiation-resistant integrated valve position transmitter is ≤±0.5%FS.

[0056] It should be noted that this valve position transmitter adopts an integrated design; please refer to [link / reference]. Figure 1A sampling resistor R1 is connected in series between the external DC voltage source and the temperature-compensated voltage regulator circuit. The current across the sampling resistor R1 is used as the signal current representing the valve opening. Firstly, this radiation-resistant integrated valve position transmitter uses a two-wire system. The power supply and signal acquisition share a single circuit. Compared to traditional three-wire valve position transmitters, the two-wire system eliminates the need for a high-power voltage regulator circuit, resulting in extremely low overall static power consumption. The three-wire system requires a built-in independent power supply regulator circuit, leading to more components, higher heat generation, and shorter lifespan in high-temperature environments. The externally connected 24V DC voltage, after passing through the sampling resistor R1, provides a voltage input fluctuation range of 12-21.6VDC to the downstream temperature-compensated voltage regulator circuit. The temperature-compensated voltage regulator circuit ensures that the output operating voltage, such as 9.000V, is maintained within this voltage fluctuation range, with an operating voltage accuracy within 0.5‰.

[0057] Secondly, in this circuit design, without considering the load current of the range adjustment circuit, the current consumed by other circuits does not exceed 4mA. Therefore, the overall power of the valve position transmitter is strictly controlled. The first-stage amplifier circuit adopts a high input impedance design, and the static operating point of the third-stage amplifier circuit is adjusted so that the small bias current meets the static requirements of the amplifier circuit. The circuit also employs temperature-compensated voltage regulator circuits, JFET constant current sources, and Wilson mirror current sources to ensure that the current consumption of the temperature-compensated voltage regulator circuit, the third-stage amplifier circuit, the sensor power supply circuit, the zero-adjustment circuit, and the temperature-compensated constant current source circuit remains constant, ensuring that the overall current consumption does not exceed 4mA. This allows the valve position transmitter to output a current signal range of 4-20mA.

[0058] Meanwhile, the sensor power supply circuit is connected to the multi-stage amplifier circuit and range adjustment circuit in the same circuit. The potentiometer in the sensor power supply circuit is directly connected to the valve, and the valve action is directly reflected through the potentiometer. This eliminates the structure of traditional split valve position transmitters, where the sensor and transmitter circuit are installed separately and the signal is transmitted through wires. This valve position transmitter integrates the sensing, signal processing and output units into a single circuit, using DC24V power supply. The internal resistance of this valve position transmitter does not exceed 600Ω, and it can output a current signal of 4-20mA. This reduces external wiring links and lowers the risk of on-site wiring errors and signal transmission interference. At the same time, it reduces the installation space occupied by the split structure, making it easier to complete the layout in compact industrial valve installation sites, improving the overall stability of the device, and is especially suitable for the high reliability requirements of nuclear power plant sites.

[0059] Furthermore, it should be noted that the number of stages in the multi-stage amplifier circuit is not limited in this invention. Any amplifier circuit with any number of stages (such as 4 stages or more) that can meet the radiation resistance requirements of this invention is within the protection scope of this invention.

[0060] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A radiation-resistant integrated valve position transmitter, characterized in that, It includes a sampling resistor, a voltage regulator circuit with temperature compensation, a sensor power supply circuit, a zero-adjustment circuit, a multi-stage amplifier circuit, a range adjustment circuit, and a constant current source circuit with temperature compensation; the multi-stage amplifier circuit includes a first-stage amplifier circuit and at least one subsequent-stage amplifier circuit connected in series. The radiation-resistant integrated valve position transmitter adopts a two-wire system, and the sampling resistor is connected in series between the external DC power supply and the temperature-compensated voltage regulator circuit. The output terminal of the temperature-compensated voltage regulator circuit serves as an internal power bus, and is connected in parallel to the power input terminal of the sensor power supply circuit, the power input terminal of the zero-adjustment circuit, the power input terminal of the multi-stage amplifier circuit, the power input terminal of the range adjustment circuit, and the power input terminal of the temperature-compensated constant current source circuit. The sensor power supply circuit uses a potentiometer as a position sampling element. Its sliding end is synchronously connected to the valve rotation shaft in the valve position transmitter. Its sliding end is also connected to the first differential input terminal of the first-stage amplifier circuit to output a voltage sampling signal that is proportional to the valve opening. The output terminal of the zero-adjustment circuit is connected to the second differential input terminal of the first-stage amplifier circuit. By adjusting the resistance value of the zero-point adjustment potentiometer in the zero-adjustment circuit, the reference voltage of the first-stage amplifier circuit is adjusted, thereby achieving zero-point calibration of the output signal. The first-stage amplifier circuit amplifies the voltage difference between the voltage signals output by the zero-adjustment circuit and the sensor power supply circuit, and then outputs it sequentially to the subsequent amplifier circuit. The voltage signal output by the subsequent amplifier circuit is then output to the range adjustment circuit. The range adjustment circuit converts the amplified voltage signal into a current signal and outputs it, using the current signal on the sampling resistor as the output current signal representing the valve opening. The first-stage amplifier circuit is provided with a JFET differential pair and a first Wilson mirror current source connected in sequence, and the first Wilson mirror current source serves as the active load of the JFET differential pair. Each stage of the multi-stage amplifier circuit is constructed from non-radiation-hardened discrete components, including transistors, junction field-effect transistors, high-precision metal film resistors, diodes, Zener diodes, and ceramic capacitors. The valve position transmitter is also equipped with: The second Wilson mirror current source has its input terminal connected to the output terminal of the temperature-compensated constant current source circuit, and its output terminal connected to each stage of the amplifier circuit; the second Wilson mirror current source provides bias current to each stage of the amplifier circuit. The constant current source circuit with temperature compensation includes a third JFET junction field-effect transistor, a fourth resistor, a fifth resistor, a first diode, a second diode, a first Zener diode, and a fourth transistor. The source of the third JFET junction field-effect transistor is connected to the input terminal of the fourth resistor, and the output terminal of the fourth resistor is connected to the gate of the third JFET junction field-effect transistor. The anode of the first diode is connected to the common connection point between the fourth resistor and the gate of the third JFET. The first diode, the second diode, and the first Zener diode are connected in series. The base of the fourth transistor is connected to the common connection point between the fourth resistor and the gate of the third JFET. The collector of the fourth transistor is connected to the internal power bus. The emitter of the fourth transistor is connected to the anode of the first Zener diode through the fifth resistor.

2. The radiation-resistant integrated valve position transmitter according to claim 1, characterized in that, The JFET differential pair includes a first JFET junction field-effect transistor and a second JFET junction field-effect transistor. The gate of the first JFET junction field-effect transistor is connected to the output terminal of the sensor power supply circuit as a first differential input terminal. The gate of the second JFET junction field-effect transistor is connected to the output terminal of the zero-adjustment circuit as a second differential input terminal. The drain of the JFET differential pair is connected to the first Wilson mirror current source. The first Wilson mirror current source includes a first transistor, a second transistor, a third transistor, a first resistor, a second resistor, and a third resistor. The collector of the first transistor is connected to the internal power bus, the base of the first transistor is connected to the drain of the first JFET, and the emitter of the first transistor is connected to the second resistor. The common connection point between the first transistor and the second resistor is connected to the base of the second transistor and the base of the third transistor, respectively. The collector of the third transistor is connected to the drain of the second JFET, and the emitter of the third transistor is connected to the third resistor. The collector of the second transistor is connected to the drain of the first JFET, and the emitter of the second transistor is connected to the first resistor.

3. The radiation-resistant integrated valve position transmitter according to claim 1, characterized in that, The first Zener diode is a Zener diode, and the voltage drop changes of the first diode, the second diode, and the first Zener diode cancel each other out when exposed to radiation.

4. The radiation-resistant integrated valve position transmitter according to claim 1, characterized in that, The temperature-compensated voltage regulator circuit includes a fourth JFET, a fifth transistor, a sixth transistor, a seventh transistor, a third diode, a second Zener diode, and a sixth resistor. The source of the fourth JFET is connected to the input of the sixth resistor. The output of the sixth resistor is connected to the gate of the fourth JFET and the collector of the sixth transistor. The base of the sixth transistor is connected to the collector. The emitter of the sixth transistor is connected to the emitter of the seventh transistor. The base of the seventh transistor is connected to the collector. The collector of the seventh transistor is connected to the anode of the third diode. The cathode of the third diode is connected to the cathode of the second Zener diode, and the anode of the second Zener diode is grounded. The output of the sixth resistor is also connected to the base of the fifth transistor. The collector of the fifth transistor is connected to the drain of the fourth JFET. The emitter of the fifth transistor is connected to other downstream circuitry.

5. The radiation-resistant integrated valve position transmitter according to claim 4, characterized in that, The fifth and sixth transistors are of the same type; when the ambient temperature rises, the seventh transistor and the third diode have negative temperature coefficients, and the second Zener diode is an avalanche diode with a positive temperature coefficient. The voltage drop changes on the seventh transistor, the third diode, and the second Zener diode cancel each other out.

6. The radiation-resistant integrated valve position transmitter according to claim 1, characterized in that, The multi-stage amplifier circuit includes a first-stage amplifier circuit, a second-stage amplifier circuit, and a third-stage amplifier circuit. The first-stage amplifier circuit is the primary amplifier circuit, and the open-loop gain formed by the second-stage amplifier circuit and the first-stage amplifier circuit exceeds 100dB. The third-stage amplifier circuit is used for power output.

7. The radiation-resistant integrated valve position transmitter according to claim 4, characterized in that, The voltage accuracy fluctuation range of the temperature-compensated voltage regulator circuit output is ≤0.5‰, and the accuracy fluctuation range of the output current signal representing the valve opening on the sampling resistor is ≤0.5%FS.

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