High-precision RTD signal analog circuit and device

Abstract

This utility model relates to a high-precision analog circuit and device for resistance temperature detectors (RTD) signals. The circuit includes a communication unit, a main control unit, and several resistance output channels. Each resistance output channel includes a resistance bias unit and multiple programmable resistance output units. The resistance output channel outputs a RTD signal that varies within a set resistance range. The resistance bias unit sets the lower limit of the set resistance range. Each programmable resistance output unit is connected to the main control unit and outputs a predetermined resistance signal or a zero-ohm resistance signal. Multiple programmable resistance output units are connected in series to form a chain. The first end of the chain is connected to the first end of the resistance bias unit, and the last end of the chain is connected to the second end of the resistance bias unit for outputting the RTD signal. The main control unit is connected to the communication unit and obtains a programmable signal for controlling the magnitude of the RTD signal through the communication unit. This utility model can output multiple controllable RTD signals.

Description

Technical Field

[0001] This utility model relates to the field of nuclear power plant equipment technology, and in particular to a high-precision thermal resistance signal analog circuit and device. Background Technology

[0002] Resistance temperature detectors (RTDs) are crucial components for monitoring temperature information in nuclear power plants. To ensure the stability and safety of nuclear power plants, regular maintenance (such as overhauls) of equipment is necessary. During these maintenance processes, precision resistance boxes are required to simulate RTD signals of varying magnitudes. However, existing precision resistance boxes require manual operation to control the signal magnitude, which is cumbersome. Furthermore, the large number of RTD signals to be simulated results in a significant workload and high labor costs. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide a high-precision analog circuit and device for RTD signal.

[0004] The technical solution adopted by this utility model to solve its technical problem is: to construct a high-precision thermal resistance signal analog circuit, including a communication unit, a main control unit and several resistance output channels;

[0005] Each of the resistance output channels includes a resistance bias unit and multiple programmable resistance output units. The resistance output channel is used to output a thermal resistance signal that varies within a set resistance range. The resistance bias unit is used to set the lower limit value of the set resistance range.

[0006] Each of the programmable resistance output units is connected to the main control unit, and the programmable resistance output unit is used to output a predetermined resistance signal or a zero-ohm resistance signal.

[0007] The multiple programmable resistance output units are connected in series to form a series chain. The first end of the series chain is connected to the first end of the resistance bias unit, and the last end of the series chain is connected to the second end of the resistance bias unit for outputting the RTD signal.

[0008] The main control unit is connected to the communication unit, and the main control unit obtains programmable signals for controlling the magnitude of the resistance temperature detector (RTD) signal through the communication unit.

[0009] Preferably, each of the programmable resistance output units includes a relay and a first resistive unit;

[0010] In each of the series chains, the normally open contact of the relay included in the programmable resistance output unit at the first end is the first end of the series chain, and the node after the normally open contacts of the relay included in the programmable resistance output unit at the last end are connected is the last end of the series chain. The common contact of the relay included in each programmable resistance output unit is connected to the normally open contacts of the relays included in other programmable resistance output units connected thereto.

[0011] In each of the programmable resistance output units, the common contact of the relays included therein is also connected to the normally open contact of the relays included therein via the first resistive unit included therein.

[0012] Each of the programmable resistance output units includes a relay whose excitation coil is connected to the main control unit.

[0013] Preferably, the number of resistance output channels is 8; and / or the number of programmable resistance output units is 12.

[0014] Preferably, the resistance values ​​of the first resistive units included in each programmable resistance output unit in the same resistance output channel are different.

[0015] Preferably, the main control unit includes an FPGA and a plurality of control instruction amplification units corresponding one-to-one with each of the resistance output channels; the FPGA is connected to the communication unit, and the control instruction amplification unit is connected to the excitation coil of the relay included in the corresponding programmable resistance output unit.

[0016] Preferably, the high-precision RTD signal analog circuit further includes a power supply unit and a hot-swappable unit;

[0017] The input terminal of the hot-swappable unit is used to connect to the power supply, the output terminal of the hot-swappable unit is connected to the input terminal of the power supply unit, and the output terminal of the power supply unit is connected to the communication unit, the main control unit, and each of the resistance output channels.

[0018] Preferably, the power supply unit includes a relay power supply unit, a first low-voltage power supply unit, and a second low-voltage power supply unit;

[0019] The input terminal of the relay power supply unit is connected to the output terminal of the hot-swappable unit, and the output terminal of the relay power supply unit is connected to the excitation coil of each relay.

[0020] The first low-voltage power supply unit is connected to the output terminal of the relay power supply unit and the main control unit;

[0021] The output terminal of the relay power supply unit of the second low-voltage power supply unit and the communication unit.

[0022] Preferably, the hot-swappable unit includes a protection chip, a switching transistor, a voltage regulator, a 31st resistor, a 32nd resistor, a 33rd resistor, a 34th resistor, a 35th resistor, a 36th resistor, a 37th resistor, a 31st capacitor, a 32nd capacitor, a 33rd capacitor, and a 34th capacitor.

[0023] The power supply terminal of the protection chip is connected to the power supply. The power supply terminal of the protection chip is also grounded through the thirty-second capacitor. The power supply terminal of the protection chip is also connected to the sensing terminal of the protection chip through the thirty-fourth resistor. The sensing terminal of the protection chip is also connected to the input terminal of the switching transistor. The gate control terminal of the protection chip is connected to the control terminal of the switching transistor through the thirty-fifth resistor. The gate control terminal of the protection chip is also grounded through the thirty-third capacitor. The output terminal of the protection chip is connected to the output terminal of the switching transistor and the input terminal of the relay power supply unit. The feedback terminal of the protection chip is connected to the output terminal of the protection chip through the thirty-sixth resistor. The feedback terminal of the protection chip is also grounded through the thirty-seventh resistor. The timer capacitor connection terminal of the protection chip is grounded through the thirty-fourth capacitor. The shutdown control terminal of the protection chip is connected to the anode of the Zener diode through the thirty-first resistor. The cathode of the Zener diode is connected to the power supply terminal of the protection chip. The anode of the Zener diode is also connected to the first terminal of the thirty-second resistor. The second terminal of the thirty-second resistor is grounded. The second terminal of the thirty-second resistor is also connected to the power supply terminal of the protection chip through the thirty-first capacitor and the thirty-third resistor.

[0024] Preferably, the communication unit includes a receiving unit for receiving low-voltage differential signals;

[0025] The receiving unit includes a first capacitor, a first resistor, a second resistor, a third resistor, a second capacitor, a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor. The first terminal of the first capacitor is connected to the positive terminal of the differential input signal. The second terminal of the first capacitor is connected to the power supply unit via the first resistor. The second terminal of the first capacitor is also connected to the main control unit via the second resistor. The second terminal of the first capacitor is also grounded via the third resistor. The first terminal of the second capacitor is connected to the negative terminal of the differential signal input. The second terminal of the second capacitor is connected to the power supply unit via the fourth resistor. The second terminal of the second capacitor is also connected to the main control unit via the fifth resistor. The second terminal of the second capacitor is also grounded via the sixth resistor. The node where the second resistor is connected to the main control unit is connected to the node where the fifth resistor is connected to the main control unit via the seventh resistor.

[0026] This invention also constructs a high-precision RTD signal simulation device, including the high-precision RTD signal simulation circuit described above.

[0027] The present invention has the following advantages: it can simulate and output multiple RTD signals and remotely control the magnitude of each RTD signal, which not only reduces manual operation steps, but also shortens the test cycle, saves human resources, and helps improve the testing efficiency of nuclear power plant equipment. Attached Figure Description

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0029] Figure 1 This is a circuit structure block diagram of a high-precision RTD signal analog circuit in some embodiments of this utility model;

[0030] Figure 2 This is a circuit diagram of the resistance output channel in some embodiments of this utility model;

[0031] Figure 3 This is a circuit diagram of the receiving unit in some embodiments of this utility model;

[0032] Figure 4 This is a circuit schematic diagram of the transmitting unit in some embodiments of this utility model;

[0033] Figure 5 This is a circuit diagram of the control command amplification unit in some embodiments of this utility model;

[0034] Figure 6 This is a circuit diagram of the relay power supply unit in some embodiments of this utility model;

[0035] Figure 7 This is a circuit diagram of the low-voltage power supply unit in some embodiments of this utility model;

[0036] Figure 8 This is a circuit diagram of the hot-swap unit in some embodiments of this utility model;

[0037] Figure 9 This is a circuit diagram of the input filtering protection unit in some embodiments of this utility model.

[0038] Explanation of reference numerals in the attached figures:

[0039] Communication unit 1; main control unit 2; resistance output channel 3; resistance bias unit 31; programmable resistance output unit 32; relay 321; first resistive unit 322; 323; power supply unit 4; hot-swap unit 5; input filter protection unit 6. Detailed Implementation

[0040] To provide a clearer understanding of the technical features, objectives, and effects of this utility model, the specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0041] In the following description, it should be understood that the orientations or positional relationships indicated by terms such as "front," "rear," "up," "down," "left," "right," "longitudinal," "horizontal," "vertical," "horizontal," "top," "bottom," "inner," "outer," "head," and "tail" are based on the orientations or positional relationships shown in the accompanying drawings, and are constructed and operated in a specific orientation. They are only for the convenience of describing this technical solution and do not indicate that the device or component referred to must have a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0042] Figure 1 This is a circuit block diagram of a high-precision RTD signal simulation circuit in some embodiments of this utility model. This high-precision RTD signal simulation circuit can simulate and output multiple RTD signals and remotely control the magnitude of each RTD signal, helping to reduce labor costs in nuclear power plants.

[0043] Please see Figure 1 The high-precision RTD signal analog circuit may include a communication unit 1, a main control unit 2, and several resistance output channels 3.

[0044] Each resistance output channel 3 may include a resistance bias unit 31 and multiple programmable resistance output units 32. The resistance output channel is used to output a resistance temperature detector (RTD) signal that varies within a set resistance range, and the resistance bias unit is used to set the lower limit value of the set resistance range.

[0045] Each programmable resistance output unit 32 is connected to the main control unit 2. The programmable resistance output unit 32 is used to output a predetermined resistance signal or a zero-ohm resistance signal.

[0046] Multiple programmable resistance output units 32 are connected in series to form a series chain. The first end of the series chain is connected to the first end of the resistance bias unit 31, and the last end of the series chain is connected to the second end of the resistance bias unit 31 for outputting the RTD signal.

[0047] Specifically, taking one of the resistance output channels 3 as an example, the control terminal of each programmable resistance output unit 32 is connected to the main control unit 2 to obtain the resistance control signal. The output resistance control signal can control its output of a predetermined resistance signal or a zero-ohm resistance signal. Except for the programmable resistance output unit 32 located at the first end, the negative terminal of the resistance signal output of each programmable resistance output unit 32 is connected to the positive terminal of the resistance signal output of one and only one programmable resistance output unit, thus obtaining the series chain. The tail end of the series chain corresponds to the positive output terminal of the RTD signal (R_OUT_CH01+, R_OUT_CH02+, ..., R_OUT_CH0N+), and the second end of the resistance bias unit 31 corresponds to the negative output terminal of the RTD signal (R_OUT_CH01-, R_OUT_CH02-, ..., R_OUT_CH0N-).

[0048] Figure 2 This is a circuit schematic diagram of the resistance output channel in some embodiments of this utility model. Figure 2 (This corresponds to the circuit schematic of the first resistance output channel). For example... Figure 2 As shown, each programmable resistance output unit 32 may include a relay 321 and a first resistive unit 322. In each series chain, the normally open contact of the relay 321 included in the programmable resistance output unit 32 at the first end is the beginning of the series chain, and the node after the normally open contacts of the relay 321 included in the programmable resistance output unit 32 at the last end are connected is the end of the series chain. The common contact of the relay 321 included in each programmable resistance output unit 32 is connected to the normally open contacts of the relay 321 included in other programmable resistance output units 32 connected thereto. In each programmable resistance output unit 32, the common contact of the relay 321 included in the same programmable resistance output unit 32 is also connected to the normally open contact of the relay 321 included in the programmable resistance output unit 32 via the first resistive unit 322 included in the programmable resistance output unit 32. The negative terminal of the excitation coil of the relay 321 included in each programmable resistance output unit 32 is connected to the main control unit 2, and the positive terminal of the excitation coil of the relay 321 included in each programmable resistance output unit 32 is connected to the first DC voltage (REL_12V, which can be provided by the power supply unit 4).

[0049] In this embodiment, the resistance control signal output by the main control unit 2 can control the excitation coil of the relay 321 to release its energization. When the excitation coil of the relay 321 is energized, the normally open contact and the common contact in the relay 321 are attracted, thereby outputting a zero-ohm resistance signal. When the excitation coil of the relay 321 is de-energized, the normally open contact and the common contact in the relay 321 are disconnected, so that a predetermined resistance value signal is output through the first resistive unit 322 connected to the relay 321. That is, the predetermined resistance value signal of the programmable resistance output unit 32 is determined by the resistance value of the first resistive unit 322. In addition, the normally open contact of the relay 321 corresponds to the negative terminal of the resistance signal output of the corresponding programmable resistance output unit 32, and the common contact of the relay 321 corresponds to the positive terminal of the resistance signal output of the corresponding programmable resistance output unit 32. It should be noted that, since relays have the advantage of low conduction impedance after the contacts are closed, in this embodiment, after the normally open contact and the common contact of relay 321 are closed, its conduction impedance can be ignored, that is, it can be regarded as zero ohms.

[0050] Optionally, relay 321 can be a G6S-2-12 relay. The G6S-2-12 relay includes two common contacts and two normally open contacts. The two common contacts and the two normally open contacts of the G6S-2-12 relay can be short-circuited. The node formed by connecting the two common contacts of the G6S-2-12 relay is defined as the common contact of relay 321, and the node formed by connecting the two normally open contacts of the G6S-2-12 relay is defined as the normally open contact of relay 321. Thus, when the G6S-2-12 relay is energized, it is equivalent to closing both normally open circuits of the G6S-2-12 relay, and these two normally open circuits are closed and connected in parallel. This further reduces the conduction impedance after the normally open contact and the common contact of relay 321 are engaged, which helps to improve the output accuracy of the RTD signal of this invention. In addition, the two normally closed contacts of the G6S-2-12 relay can be left floating.

[0051] In some embodiments, such as Figure 2 As shown, each programmable resistance output unit 32 may also include a filter capacitor 323, and the positive terminal of the relay 321 is grounded through the filter capacitor 323.

[0052] It is easy to understand that the magnitude of the RTD signal output by the resistance output channel 3 is determined by the actual excitation of each relay 321 in the programmable resistance output unit 32, so as to combine RTD signals of various resistance values.

[0053] Since the most commonly used RTD (Resistor of Temperature) detector (RTD) in nuclear power plants is the PT100 (the output signal of the simulated PT100 resistor is most frequently used during overhauls), the resistance range of the PT100 resistor from 0°C to 500°C corresponds to 100Ω to 280.98Ω. Accordingly, the resistance value can be set from 98.8Ω to 300Ω to ensure that the resistance range of the PT100 resistor output is encompassed. Furthermore, the resistance bias unit 31 can include a resistor with a resistance of 98.8Ω. To improve the accuracy of the output RTD signal, this resistor is preferably a readily available high-precision, low-temperature drift resistor.

[0054] In some embodiments, the number of resistance output channels 3 can be 8, which means that the high-precision RTD signal analog circuit can simultaneously output 8 RTD signals ranging from 98.8Ω to 300Ω.

[0055] It's easy to understand that the more programmable resistance output units 32 there are, the better it is to output more different resistance values ​​of RTD signals, but the cost is also higher. Therefore, as... Figure 2 As shown, the number of programmable resistance output units 32 is preferably 12, which can ensure the diversity of resistance values ​​of the RTD signal without making the cost of the programmable resistance output units 32 too high.

[0056] In order to accurately output different resistance values ​​and to maximize the diversity of resistance values ​​of the RTD signal, in some embodiments, the resistance values ​​of the first resistive units 322 included in each programmable resistance output unit 32 in the same resistance output channel 3 are different.

[0057] In one specific embodiment, the resistance values ​​of the 12 first resistive units 322 in the same resistance output channel 3 can be 100Ω, 50Ω, 25Ω, 12.5Ω, 6.25Ω, 3.125Ω, 1.56Ω, 1.2Ω, 780mΩ, 390mΩ, 195mΩ and 98mΩ respectively.

[0058] In some embodiments, the first resistive unit 322 may include a twenty-first resistor R21 and a twenty-second resistor R22. The twenty-first resistor R21 and the twenty-second resistor R22 are connected in parallel. It is readily understood that the resistance value of the first resistive unit 322 can be controlled by adjusting the resistance values ​​of the twenty-first resistor R21 and the twenty-second resistor R22.

[0059] like Figure 1As shown, the main control unit 2 is connected to the communication unit 1. The main control unit 2 obtains the programmable control signal used to control the magnitude of the RTD signal through the communication unit 1. Specifically, the programmable control signal can be obtained from a control terminal, which includes, but is not limited to, a host computer, a computer, or a mobile terminal (such as a mobile phone). Understandably, staff can operate the control terminal to input the corresponding programmable control signal to the main control unit 2 as needed, thereby obtaining the RTD signal with the corresponding resistance value, thus realizing remote control of the RTD signal.

[0060] In some embodiments, the communication unit 1 may include a receiving unit for receiving low-voltage differential signals.

[0061] Figure 3 This is a circuit diagram of the receiving unit in some embodiments of the present invention. The receiving unit may include a first protection tube D1, a first capacitor C1, a first resistor R1, a second resistor R2, a third resistor R3, a second capacitor C2, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. The first terminal of the first capacitor C1 is used to connect to the positive terminal of the differential input signal. The second terminal of the first capacitor C1 is connected to the third DC voltage (VCC_2V5, which can be provided by the power supply unit 4) via the first resistor R1. The second terminal of the first capacitor C1 is also connected to the main control unit 2 via the second resistor R2. The second terminal of the first capacitor C1 is also grounded via the third resistor R3. The first terminal of the second capacitor C2 is used to connect to the negative terminal of the differential signal input. The second terminal of the second capacitor C2 is connected to the third DC voltage via the fourth resistor R4. The second terminal of the second capacitor C2 is also connected to the main control unit 2 via the fifth resistor R5. The second terminal of the second capacitor C2 is also grounded via the sixth resistor R6. The node after the second resistor R2 is connected to the main control unit 2 is connected to the node after the fifth resistor R5 is connected to the main control unit 2 via the seventh resistor R7. The first terminals of the first capacitor C1 and the first terminals of the second capacitor C2 are also grounded via the first protection tube D1.

[0062] In this embodiment, the receiving unit can receive low-amplitude (approximately 350mV) low-voltage differential signals, enabling the transmission of serial data at speeds up to several thousand Mbps. Because the voltage signal amplitude is low and it can be driven in constant current source mode, it generates extremely low noise and consumes very little power, with power consumption remaining almost constant regardless of frequency. Furthermore, using a differential method to acquire the programmable signal reduces the impact of common-mode noise on the programmable signal. Additionally, the first protection diode D1 includes a conventional electrostatic discharge (ESD) protection diode or a transient voltage suppression diode.

[0063] In order to enable the control terminal to obtain the operating status of the high-precision RTD signal analog circuit (including the real-time output RTD signal magnitude of each resistance value output channel), in some embodiments, the communication unit 1 may also include a transmitting unit for transmitting low-voltage differential signals.

[0064] Figure 4 This is a circuit diagram of the transmitting unit in some embodiments of the present invention. The transmitting unit may include a second protection transistor D2, a third capacitor C3, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a fourth capacitor C4, an eleventh resistor R11, a twelfth resistor R12, and a thirteenth resistor R13. The first terminal of the third capacitor C3 is used to output a positive differential output signal. The second terminal of the third capacitor C3 is connected to a third DC voltage via the eighth resistor R8. The second terminal of the third capacitor C3 is also connected to the main control unit 2 via the ninth resistor R9. The second terminal of the third capacitor C3 is also grounded via the tenth resistor R10. The first terminal of the fourth capacitor C4 is used to output a negative low voltage differential signal. The second terminal of the fourth capacitor C4 is connected to the third DC voltage via the eleventh resistor R11. The second terminal of the fourth capacitor C4 is also connected to the main control unit 2 via the twelfth resistor R12. The second terminal of the fourth capacitor C4 is also grounded via the thirteenth resistor R13. The first terminals of the third capacitor C3 and the fourth capacitor C4 are also grounded via the second protection transistor D2.

[0065] Understandably, the working principle of the transmitting unit is similar to that of the receiving unit. Therefore, the advantages of the transmitting unit can be found above and will not be repeated here.

[0066] In some embodiments, the main control unit 2 may include an FPGA and a plurality of control command amplification units corresponding one-to-one with each resistance output channel 3. The FPGA is connected to the communication unit 1, and the control command amplification unit 22 is connected to the excitation coil of the relay 321 included in the corresponding programmable resistance output unit 32. Since the command signal voltage that the FPGA can output is relatively low (usually 3.3V), while the rated voltage of the relay 321 is 12V, the FPGA cannot directly drive the excitation coil of the relay 321. In this embodiment, the voltage amplitude of the control command (i.e., the resistance control signal) output by the FPGA is amplified by the control command amplification unit, thereby controlling whether the excitation coil of the relay 321 is energized. In addition, the number of control command amplification units is the same as the number of resistance output channels 3.

[0067] Figure 5 This is a circuit diagram of the control command amplification unit in some embodiments of this utility model. Figure 5 This corresponds to the circuit schematic of the control command amplification unit corresponding to the first resistance output channel. When the number of programmable resistance output units 32 is preferably 12, correspondingly, as shown in the circuit schematic of the control command amplification unit corresponding to the first resistance output channel. Figure 5As shown, each control command amplification unit may include a first Darlington transistor array U10, a second Darlington transistor array U8, a seventy-ninth resistor R79, an eightieth resistor R80, an eighty-first resistor R81, an eighty-second resistor R82, an eighty-third resistor R83, an eighty-fourth resistor R84, an eighty-fifth resistor R85, an eighty-sixth resistor R86, an eighty-seventh resistor R87, an eighty-eighth resistor R88, an eighty-ninth resistor R89, and a ninetieth resistor R90. The base input terminals (pins 1B to 6B) of the first Darlington transistor array U10 are connected to the FPGA. The collector output terminals (pins 1C to 6C) of the first Darlington transistor array U10 are connected one-to-one to the excitation coils of the relays 321 in the six programmable resistor output units 32. The base input terminals (pins 1C to 6C) of the first Darlington transistor array U10 are also connected one-to-one to ground via resistors R79, R80, R81, R82, R83, and R84. The common cathode input terminal (COM pin) of the first Darlington transistor array U10 is connected to the first DC voltage. The common emitter (corresponding to pin E) of the Darlington transistor array U10 is grounded; the first to sixth base electrode inputs of the second Darlington transistor array U8 are connected to the FPGA respectively; the first to sixth collector outputs of the second Darlington transistor array U8 are connected one-to-one to the excitation coils of the relays 321 in the other six programmable resistance output units 32; the first to sixth base electrode inputs of the second Darlington transistor array U8 are also connected one-to-one to ground via resistors R85 (eighth-fifth), R86 (eighth-sixth), R87 (eighth-seventh), R88 (eighth-eighth), R89 (eighth-ninth), and R90 (ninth); the common cathode input of the second Darlington transistor array U8 is connected to the first DC voltage; and the common emitter of the second Darlington transistor array U8 is grounded.

[0068] In this embodiment, the first Darlington transistor array U10 and the second Darlington transistor array U8 can be Darlington transistor arrays of model ULN2003A. Please refer to [link to relevant documentation]. Figure 2 and Figure 5 When the CH01_IO01 signal output by the FPGA is high, the IC pin and COM pin of the first Darlington transistor array U10 are turned on, which is equivalent to demagnetizing the corresponding relay 321. The corresponding programmable resistance output unit 32 outputs a predetermined resistance signal. Conversely, when the CH01_IO01 signal output by the FPGA is low, the corresponding relay 321 is energized, and the corresponding programmable resistance output unit 32 outputs a zero-ohm resistance signal.

[0069] It should be noted that this embodiment utilizes the advantage of FPGA (i.e., Field Programmable Gate Array) having a large number of IO ports, and can achieve the control of multiple programmable resistance output units 32 by cooperating with the control instruction amplification unit.

[0070] In some embodiments, such as Figure 1 As shown, the high-precision RTD signal analog circuit may also include a power supply unit 4 and a hot-swappable unit 5.

[0071] The input terminal of the hot-swap unit 5 is used to connect to a power supply (24V DC voltage). The output terminal of the hot-swap unit 5 is connected to the input terminal of the power supply unit 4. The output terminal of the power supply unit 4 is connected to the communication unit 1, the main control unit 2, and each resistance output channel 3. The power supply unit 4 provides the DC voltage required for the operation of the communication unit 1 and the main control unit 2, including a first DC voltage REL_12V for powering the relay 321, a second DC voltage 3.3V for powering the FPGA, and a third DC voltage VCC_2V5 for powering the communication unit 1. Furthermore, the hot-swap unit 5 enables hot-swapping functionality.

[0072] It should be noted that the power supply can be provided by an existing 24V DC power supply, and no specific restrictions are made here.

[0073] In some embodiments, the power supply unit 4 may include a relay power supply unit for outputting a first DC voltage, a first low-voltage power supply unit for outputting a second DC voltage, and a second low-voltage power supply unit for outputting a third DC voltage. The input terminal of the relay power supply unit is connected to the output terminal of the hot-swap unit 5 to obtain a 24V DC voltage from the hot-swap unit 5. The output terminal of the relay power supply unit is connected to the excitation coil of each relay 321 to provide a 12V DC voltage (i.e., the first DC voltage) to the relay 321. The first low-voltage power supply unit is connected to the output terminal of the relay power supply unit to obtain the first DC voltage from the relay power supply unit. The first low-voltage power supply unit is used to convert the first DC voltage into a second DC voltage. The first low-voltage power supply unit is also connected to the main control unit 2 to provide a 3.3V DC voltage (i.e., the second DC voltage) to the FPGA in the main control unit 2. The output terminal of the second low-voltage power supply unit is connected to the relay power supply unit to obtain the first DC voltage from the relay power supply unit. The second low-voltage power supply unit is used to convert the first DC voltage into a third DC voltage. The second low-voltage power supply unit is also connected to the communication unit 1 to provide a 2.5V DC voltage (i.e., the third DC voltage) to the communication unit 1.

[0074] Figure 6This is a circuit diagram of the relay power supply unit in some embodiments of this utility model. The relay power supply unit may include an isolated power supply module DC1, a second inductor L2, a forty-first capacitor C41, a forty-second capacitor C42, a forty-third capacitor C43, a forty-fourth capacitor C44, a forty-fifth capacitor C45, a forty-sixth capacitor C46, ​​a forty-seventh capacitor C47, a forty-eighth capacitor C48, a forty-ninth capacitor C49, a second transient suppression diode TVS2, a first ferrite bead B1, and a second ferrite bead B2. The isolated power supply module DC1 can be an isolated power supply module of model VRB2412YMD-20WR3. For the specific circuit connection relationship of the relay power supply unit, please refer to [reference needed]. Figure 6 This will not be elaborated upon here. Of course, the relay power supply unit can also be replaced by an existing 24V to 12V DC power supply module.

[0075] Figure 7 This is a circuit diagram of the low-voltage power supply unit in some embodiments of this utility model. It should be noted that... Figure 7 The circuit diagram of the low-voltage power supply unit shown is applicable to both the first and second low-voltage power supply units. The first or second low-voltage power supply unit may include a switch control chip U21, a third inductor L3, capacitors C51 (51), C52 (52), C54 (54), C55 (55), C56 (56), C57 (57), C58 (58), C59 (59), resistors R50 (50), R51 (51), R54 (54), R55 (55), and a magnetic bead B8. Specifically, the power supply terminal of the switch control chip U21 is connected to the relay power supply unit to obtain the first DC voltage. The power supply terminal of the switch control chip U21 is also grounded through capacitor C54 (54). Capacitors C55 (55) and C56 (56) are connected in parallel with capacitor C54 (54). The switch control terminal of the switch control chip U21 is connected to one end of the third inductor L3. The other end of the third inductor L3 is connected to one end of the eighth ferrite bead B8, one end of the fifty-seventh capacitor C57, one end of the fifty-eighth capacitor C58, and one end of the fifty-ninth capacitor C59. The other end of the eighth ferrite bead B8 is used to output the second or third DC voltage. Figure 7(The third DC voltage is not shown in the diagram). The other ends of the fifty-seventh capacitor C57, the fifty-eighth capacitor C58, and the fifty-ninth capacitor C59 are grounded. The switch control terminal of the switch control chip U21 is also connected to the gate drive terminal of the switch control chip U21 via the fifty-second capacitor C52. The enable terminal of the switch control chip U21 is connected to the first DC voltage via the fifty-first resistor R51. The enable terminal of the switch control chip U21 is also grounded via the fifty-fifth resistor R55. The feedback terminal of the switch control chip U21 is connected to the other end of the eighth magnetic bead B8 via the fiftieth resistor R50. The feedback terminal of the switch control chip U21 is also grounded via the fifty-fourth resistor R54.

[0076] In this embodiment, the switch control chip U21 can be a TPS561201DDCR switch control chip. Although the first low-voltage power supply unit and the second low-voltage power supply unit in this embodiment use the same circuit principle, the DC voltage output at the other end of the eighth ferrite bead B8 can be controlled by adjusting the resistance ratio of the 50th resistor R50 to the 54th resistor R54. That is, in this embodiment, the difference between the first low-voltage power supply unit and the second low-voltage power supply unit is that the resistance ratio of the 50th resistor R50 to the 54th resistor R54 in the first low-voltage power supply unit is different from that in the second low-voltage power supply unit. Of course, the first low-voltage power supply unit can also be replaced by an existing 12V to 3.3V DC power supply module, and the second low-voltage power supply unit can also be replaced by an existing 12V to 2.5V DC power supply module.

[0077] Figure 8 This is a circuit diagram of a hot-swappable unit in some embodiments of the present invention. The hot-swappable unit 5 may include a protection chip U1, a switching transistor Q1, a Zener diode D3, a 31st resistor R31, a 32nd resistor R32, a 33rd resistor R33, a 34th resistor R34, a 35th resistor R35, a 36th resistor R36, a 37th resistor R37, a 31st capacitor C31, a 32nd capacitor C32, a 33rd capacitor C33, a 34th capacitor C34, and a 35th capacitor C35.

[0078] Specifically, the power supply terminal of protection chip U1 is connected to the power supply. The power supply terminal of protection chip U1 is also grounded via capacitor C32 (32nd capacitor). The power supply terminal of protection chip U1 is also connected to the sensing terminal of protection chip U1 via resistor R34 (34th resistor). The sensing terminal of protection chip U1 is also connected to the input terminal of switching transistor Q1. The gate control terminal of protection chip U1 is connected to the control terminal of switching transistor Q1 via resistor R35 (35th resistor). The gate control terminal of protection chip U1 is also grounded via capacitor C33 (33rd capacitor). The output terminal of protection chip U1 is connected to the output terminal of switching transistor Q1 and the input terminal of the relay power supply unit. The feedback terminal of protection chip U1 is connected to the protection chip U1 via resistor R36 (36th resistor). The output terminal of protection chip U1 is connected to the feedback terminal via resistor R37 (37th resistor). The timer capacitor connection terminal of protection chip U1 is connected to the ground via capacitor C34 (34th capacitor). Capacitor C35 (35th capacitor) is connected in parallel with capacitor C34 (34th capacitor). The shutdown control terminal of protection chip U1 is connected to the anode of Zener diode D3 via resistor R31 (31st resistor). The cathode of Zener diode D3 is connected to the power supply terminal of protection chip U1. The anode of Zener diode D3 is also connected to the first terminal of resistor R32 (32nd resistor). The second terminal of resistor R32 (32nd resistor) is grounded. The second terminal of resistor R32 (32nd resistor) is also connected to the power supply terminal of protection chip U1 via capacitor C31 (31st capacitor) and resistor R33 (33rd resistor).

[0079] In this embodiment, the protection chip U1 can be a surge protector of model LT4356IMS-1.

[0080] In some embodiments, such as Figure 1 As shown, the high-precision RTD signal analog circuit may also include an input filter protection unit 6. The input filter protection unit 6 is connected between the hot-swappable unit 5 and the power supply to filter the power supply and prevent damage to subsequent circuits due to input overcurrent or input overvoltage.

[0081] Figure 9This is a circuit diagram of the input filtering protection unit 6 in some embodiments of this utility model. The input filtering protection unit 6 may include a fuse F1, a varistor MO1, a diode D4, a first transient suppression diode TVS1, a ninth capacitor C9, a common-mode inductor L1, and a tenth capacitor C10. The first end of the fuse F1 is used to connect to the positive terminal of the power supply. The second end of the fuse F1 is connected to the first end of the varistor MO1 and the anode of the diode D4. The cathode of the diode D4 is connected to the first end of the first transient suppression diode TVS1 and the first end of the ninth capacitor C9. The node formed by connecting the second end of the varistor MO1, the second end of the first transient suppression diode TVS1, and the second end of the ninth capacitor C9 is used to connect to the negative terminal of the power supply. The cathode of the diode D4 is connected to the first end of the tenth capacitor C10 through the first coil of the common-mode inductor L1. The second end of the ninth capacitor C9 is connected to the second end of the tenth capacitor C10 through the second coil of the common-mode inductor L1. The first and second ends of the tenth capacitor C10 are connected to the hot-swap unit 5 to provide a 24V DC voltage to the hot-swap unit 5.

[0082] In this embodiment, fuse F1 prevents overcurrent damage to downstream circuits. The combination of varistor MO1 and transient voltage suppressor diode TVS1 prevents overvoltage damage to downstream circuits. The ninth capacitor C9, common-mode inductor L1, and tenth capacitor C10 form a filter circuit that filters the power supply input to the hot-swap unit 5.

[0083] Understandably, the technical solution of this utility model can simulate the output of multiple RTD signals and remotely control the magnitude of each RTD signal. This not only reduces manual operation steps but also shortens the testing cycle, saves human resources, and helps improve the testing efficiency of nuclear power plant equipment.

[0084] This invention provides a high-precision RTD signal simulation device, which includes the high-precision RTD signal simulation circuit provided in the embodiments of this invention.

[0085] It is understood that the above embodiments only illustrate preferred embodiments of the present utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present utility model patent. It should be noted that for those skilled in the art, the above technical features can be freely combined, and several modifications and improvements can be made without departing from the concept of the present utility model, all of which fall within the protection scope of the present utility model. Therefore, all equivalent transformations and modifications made within the scope of the claims of the present utility model should fall within the coverage of the claims of the present utility model.

Claims

1. A high-precision analog circuit for resistance temperature detector (RTD) signals, characterized in that, It includes a communication unit, a main control unit, and several resistance output channels; Each of the resistance output channels includes a resistance bias unit and multiple programmable resistance output units. The resistance output channel is used to output a thermal resistance signal that varies within a set resistance range. The resistance bias unit is used to set the lower limit value of the set resistance range. Each of the programmable resistance output units is connected to the main control unit, and the programmable resistance output unit is used to output a predetermined resistance signal or a zero-ohm resistance signal. The multiple programmable resistance output units are connected in series to form a series chain. The first end of the series chain is connected to the first end of the resistance bias unit, and the last end of the series chain is connected to the second end of the resistance bias unit for outputting the RTD signal. The main control unit is connected to the communication unit, and the main control unit obtains programmable signals for controlling the magnitude of the resistance temperature detector (RTD) signal through the communication unit.

2. The high-precision RTD signal analog circuit according to claim 1, characterized in that, Each of the programmable resistance output units includes a relay and a first resistive unit; In each of the series chains, the normally open contact of the relay included in the programmable resistance output unit at the first end is the first end of the series chain, and the node after the normally open contacts of the relay included in the programmable resistance output unit at the last end are connected is the last end of the series chain. The common contact of the relay included in each programmable resistance output unit is connected to the normally open contacts of the relays included in other programmable resistance output units connected thereto. In each of the programmable resistance output units, the common contact of the relays included therein is also connected to the normally open contact of the relays included therein via the first resistive unit included therein. Each of the programmable resistance output units includes a relay whose excitation coil is connected to the main control unit.

3. The high-precision RTD signal analog circuit according to claim 2, characterized in that, The number of resistance output channels is 8; and / or the number of programmable resistance output units is 12.

4. The high-precision RTD signal analog circuit according to claim 2, characterized in that, The resistance values ​​of the first resistive units included in each of the programmable resistance output units in the same resistance output channel are different.

5. The high-precision RTD signal analog circuit according to claim 2, characterized in that, The main control unit includes an FPGA and several control instruction amplification units corresponding one-to-one with each of the resistance output channels; the FPGA is connected to the communication unit, and the control instruction amplification unit is connected to the excitation coil of the relay included in the corresponding programmable resistance output unit.

6. The high-precision RTD signal analog circuit according to any one of claims 2 to 5, characterized in that, The high-precision RTD signal analog circuit also includes a power supply unit and a hot-swap unit; The input terminal of the hot-swappable unit is used to connect to the power supply, the output terminal of the hot-swappable unit is connected to the input terminal of the power supply unit, and the output terminal of the power supply unit is connected to the communication unit, the main control unit, and each of the resistance output channels.

7. The high-precision RTD signal analog circuit according to claim 6, characterized in that, The power supply unit includes a relay power supply unit, a first low-voltage power supply unit, and a second low-voltage power supply unit; The input terminal of the relay power supply unit is connected to the output terminal of the hot-swappable unit, and the output terminal of the relay power supply unit is connected to the excitation coil of each relay. The first low-voltage power supply unit is connected to the output terminal of the relay power supply unit and the main control unit; The output terminal of the relay power supply unit of the second low-voltage power supply unit and the communication unit.

8. The high-precision RTD signal analog circuit according to claim 7, characterized in that, The hot-swappable unit includes a protection chip, a switching transistor, a voltage regulator, a 31st resistor, a 32nd resistor, a 33rd resistor, a 34th resistor, a 35th resistor, a 36th resistor, a 37th resistor, a 31st capacitor, a 32nd capacitor, a 33rd capacitor, and a 34th capacitor; The power supply terminal of the protection chip is connected to the power supply. The power supply terminal of the protection chip is also grounded through the thirty-second capacitor. The power supply terminal of the protection chip is also connected to the sensing terminal of the protection chip through the thirty-fourth resistor. The sensing terminal of the protection chip is also connected to the input terminal of the switching transistor. The gate control terminal of the protection chip is connected to the control terminal of the switching transistor through the thirty-fifth resistor. The gate control terminal of the protection chip is also grounded through the thirty-third capacitor. The output terminal of the protection chip is connected to the output terminal of the switching transistor and the input terminal of the relay power supply unit. The feedback terminal of the protection chip is connected to the output terminal of the protection chip through the thirty-sixth resistor. The feedback terminal of the protection chip is also grounded through the thirty-seventh resistor. The timer capacitor connection terminal of the protection chip is grounded through the thirty-fourth capacitor. The shutdown control terminal of the protection chip is connected to the anode of the Zener diode through the thirty-first resistor. The cathode of the Zener diode is connected to the power supply terminal of the protection chip. The anode of the Zener diode is also connected to the first terminal of the thirty-second resistor. The second terminal of the thirty-second resistor is grounded. The second terminal of the thirty-second resistor is also connected to the power supply terminal of the protection chip through the thirty-first capacitor and the thirty-third resistor.

9. The high-precision RTD signal analog circuit according to claim 6, characterized in that, The communication unit includes a receiving unit for receiving low-voltage differential signals; The receiving unit includes a first capacitor, a first resistor, a second resistor, a third resistor, a second capacitor, a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor. The first terminal of the first capacitor is connected to the positive terminal of the differential input signal. The second terminal of the first capacitor is connected to the power supply unit via the first resistor. The second terminal of the first capacitor is also connected to the main control unit via the second resistor. The second terminal of the first capacitor is also grounded via the third resistor. The first terminal of the second capacitor is connected to the negative terminal of the differential signal input. The second terminal of the second capacitor is connected to the power supply unit via the fourth resistor. The second terminal of the second capacitor is also connected to the main control unit via the fifth resistor. The second terminal of the second capacitor is also grounded via the sixth resistor. The node where the second resistor is connected to the main control unit is connected to the node where the fifth resistor is connected to the main control unit via the seventh resistor.

10. A high-precision RTD signal simulation device, characterized in that, Includes the high-precision RTD signal analog circuit as described in any one of claims 1 to 9.

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