A nuclear measurement analog quantity transmission method based on a feedback compensation circuit

Abstract

The present application relates to nuclear radiation detection technical field, provide a kind of nuclear measurement analog quantity transmission method based on feedback compensation circuit, the hardware part used by this method includes ARM chip, digital-analog converter, digital potentiometer, operational amplifier, isolated voltage current converter, isolation chip, A / D conversion chip, the ARM chip is connected with digital-analog converter, digital potentiometer respectively, the ARM chip is connected with A / D conversion chip after isolation chip, the first operational amplifier is connected with digital-analog converter, digital potentiometer, isolated voltage current converter respectively, the output current of isolated voltage current converter is connected with A / D conversion chip through precision resistance, second operational amplifier.The present application method can be promptly revised output current according to the comparison result of output signal and input signal, and the mode of feedback compensation is used to adjust input signal, improves output accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nuclear radiation detection technology, in particular to a nuclear measurement analog quantity transmission method based on a feedback compensation circuit. BACKGROUND

[0002] Analog quantity transmission is one of the conventional hard-wired information interaction means, which has the characteristics of fast reaction, high reliability and low failure rate. At present, the digital control system (DCS) of nuclear power plants still uses a large number of hard-wired methods, and some important channels require analog quantity transmission information.

[0003] In the process of nuclear radiation monitoring, the signal processing unit usually completes the nuclear measurement data processing and analog quantity output. The analog quantity is generally 4mA-20mA current, which corresponds to the range of the measured value. The accuracy of the analog quantity determines the accuracy of the transmitted data.

[0004] The analog quantity is generated by a digital-to-analog converter and an isolated voltage-to-current converter, so there is inevitably a certain non-linear error. In some special application scenarios, the output current accuracy cannot meet the technical requirements, and needs to be compensated and corrected. SUMMARY

[0005] The purpose of the present application is to overcome the above technical deficiencies, and to provide a nuclear measurement analog quantity transmission method based on a feedback compensation circuit. According to the comparison result of the output signal and the input signal, the input signal is adjusted by feedback compensation, so that the output current can be corrected in time, and the output accuracy is improved.

[0006] To achieve the above purpose, the technical solution of the present application is as follows.

[0007] A nuclear measurement analog quantity transmission method based on a feedback compensation circuit, the hardware used in this method includes an ARM chip, a digital-to-analog converter, a digital potentiometer, a first operational amplifier, an isolated voltage-to-current converter, an isolation chip, an A / D conversion chip, a precision resistor, a second operational amplifier, etc.

[0008] The ARM chip is connected to the digital-to-analog converter and the digital potentiometer, respectively. The ARM chip is connected to the A / D conversion chip through the isolation chip. The first operational amplifier is connected to the digital-to-analog converter, the digital potentiometer and the isolated voltage-to-current converter, respectively. The output current of the isolated voltage-to-current converter is connected to the A / D conversion chip through the precision resistor and the second operational amplifier.

[0009] The method comprises the following steps:

[0010] (1) Program initialization, each chip is initialized, and the initial resistance value of the digital potentiometer is set to the minimum value.

[0011] (2) When powered on for the first time, the corresponding magnifications of the first operational amplifier circuit at the 256 tap positions of the digital potentiometer are sequentially stored in the internal storage module of the ARM chip. This operation is not required for subsequent work.

[0012] The specific operations are as follows:

[0013] (2-1) The ARM chip sets the core measurement analog output current value I to 12mA, the middle value of the current range of 4mA to 20mA. The digital-to-analog converter output voltage value V is converted to 2.5V, the middle value of the voltage range of 0V to 5V, by the corresponding relationship. The conversion formula is: V = (I-4) * 5 / 16;

[0014] (2-2) Based on the digital-to-analog converter communication protocol, send a command to control the digital-to-analog converter to output a voltage value of 2.5V as the input of the first operational amplifier; measure the voltage value across the precision resistor through the A / D conversion chip, and convert it to obtain the final output analog value;

[0015] (2-3) Based on the digital potentiometer communication protocol, the ARM chip sends a control command to adjust the resistance value of the digital potentiometer. The command range is 0x00 to 0xFF. 0x00 corresponds to the minimum resistance value, so the first operational amplifier circuit has the minimum amplification factor. 0xFF corresponds to the maximum resistance value, so the first operational amplifier circuit has the maximum amplification factor.

[0016] (2-4) Compare the output analog value and the set analog value to obtain the system amplification factor. Finally, the ARM chip stores the amplification factors corresponding to the 256 tap positions of the digital potentiometer in the internal storage module.

[0017] (3) During normal operation, the ARM program uses feedback and compensation to correct the output current value. The specific operations are as follows:

[0018] (3-1) After converting the nuclear measurement value into a 4mA to 20mA analog quantity according to the specified range and conversion formula, the output voltage value is obtained and the output of the digital-to-analog converter is controlled;

[0019] (3-2) Use the feedback circuit composed of precision resistors and A / D conversion chip to measure the error between the output analog quantity and the analog quantity converted by the ARM program;

[0020] (3-3) If the error exceeds the specified range, calculate the target amplification factor m = converted analog value a / output analog value b, use the ARM program to query the amplification factor storage array corresponding to the tap position, find the tap position closest to the target amplification factor, write the position into the digital potentiometer, and combine the ARM program to control the compensation circuit composed of the digital potentiometer and the first operational amplifier to perform real-time compensation for the output current.

[0021] In this technical solution, the ARM chip uses the GD32F450 chip, operating at a +3.3V voltage. The SPI interface isolation chip uses the ADuM1411 chip. This isolation chip isolates the SPI interface between the ARM chip and the A / D converter chip, improving the anti-interference performance of the transmitted signal.

[0022] In the above technical solution, the current output circuit is composed of the digital-to-analog converter AD5663, the first operational amplifier TLE2072, the isolated voltage-to-current converter 1B22, capacitors, and resistors. The digital-to-analog converter SPI interface is connected to the ARM chip through the isolation chip; the digital-to-analog converter output voltage serves as the input of the first operational amplifier; and the output of the first operational amplifier serves as the input of the voltage-to-current converter.

[0023] In the above technical solution, a feedback circuit consists of a precision resistor with a ±0.01% tolerance, a second operational amplifier (TLE2072), an AD7327 A / D converter chip, and an ADuM1411 SPI interface isolation chip. The voltage across the precision resistor is followed and processed by the second operational amplifier (TLE2072) before being input to the A / D converter chip. The SPI interface of the A / D converter chip is connected to the ARM chip via the isolation chip. The precision resistor has a resistance of 100Ω. The second operational amplifier functions as a voltage follower.

[0024] In the above technical solution, the compensation circuit consists of a first operational amplifier TLE2072, a digital potentiometer CL4801, a capacitor, and a resistor. The digital potentiometer is connected to an ARM chip via an SPI interface. The CL4801 chip is a 10kΩ digital potentiometer that supports the SPI protocol and has 256 adjustable taps. The digital potentiometer is controlled by the ARM chip to change the amplification factor of the compensation circuit. The resistor value is 1MΩ. The amplification factor of the compensation circuit is controlled within a range of 0 to 1%.

[0025] The nuclear measurement analog quantity transmission method based on the feedback compensation circuit of the present invention adopts the feedback compensation to adjust the input signal and promptly correct the output current. Compared with the existing technology, it has the following advantages:

[0026] 1. Analog transmission has certain feedback compensation adjustment capabilities and strong environmental adaptability;

[0027] 2. The analog transmission has small nonlinear error and high accuracy, which can meet the needs of more application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a connection block diagram of the hardware part in the method of the present invention.

[0029] Figure 2 This is a partial circuit connection diagram of the ARM chip in an embodiment of the present invention.

[0030] Figure 3 4 is a connection diagram of the current output circuit in an embodiment of the present invention.

[0031] Figure 4 4 is a connection diagram of the feedback circuit in an embodiment of the present invention.

[0032] Figure 5 2 is a connection diagram of the compensation circuit in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The technical solutions of the present invention will be described clearly and completely below with reference to the accompanying drawings and embodiments.

[0034] like Figure 1 As shown, this embodiment provides a method for transmitting nuclear measurement analog quantities based on a feedback compensation circuit. The hardware used in this method consists of an ARM chip, a digital-to-analog converter, a digital potentiometer, a first operational amplifier, an isolated voltage-to-current converter, an isolation chip, an A / D conversion chip, a precision resistor, a second operational amplifier, and the like. The ARM chip is connected to the digital-to-analog converter and the digital potentiometer, respectively. The ARM chip is connected to the A / D conversion chip after passing through the isolation chip. The first operational amplifier is connected to the digital-to-analog converter, the digital potentiometer, and the isolated voltage-to-current converter, respectively. The output current of the isolated voltage-to-current converter is connected to the A / D conversion chip via a precision resistor and a second operational amplifier.

[0035] In the above embodiment, the ARM chip uses the GD32F450 chip. The ARM chip directly controls the digital-to-analog converter and the digital potentiometer chip based on the SPI protocol; the A / D conversion chip is controlled by the isolation chip. The digital potentiometer uses the CL4801 chip that supports the SPI protocol. Based on the SPI protocol, the ARM chip encodes and sends a control command (0x00 to 0xFF) to control the resistance of the digital potentiometer. When the command is 0x00, the resistance value is the smallest, and the corresponding amplification factor is the smallest; when the command is 0xFF, the resistance value is the largest, and the corresponding amplification factor is the largest. When powered on for the first time, the amplification factors of the amplifier circuit at the 256 tap positions of the digital potentiometer need to be stored in sequence in the internal storage module of the ARM chip.

[0036] like Figure 2 As shown in the figure, the ARM chip circuit consists of the ARM chip GD32F450, a crystal oscillator, resistors, and capacitors. The ARM chip power pins are all connected to +3.3V, and the ground pins are all connected to GND. The first SPI interface pin is connected to the digital-to-analog converter; the second SPI interface pin is connected to the digital potentiometer; and the third SPI interface pin is connected to the isolation chip.

[0037] like Figure 3As shown in the figure, the current output circuit consists of the AD5663 digital-to-analog converter, the first operational amplifier TLE2072, an isolated voltage-to-current converter 1B22, capacitors, and resistors. The 1B22 is supplied with a ±15V supply voltage. The output terminal is connected to a precision resistor.

[0038] like Figure 4 As shown in the figure, the feedback circuit consists of a precision resistor with a ±0.01% tolerance, a second operational amplifier (TLE2072), an AD7327 A / D converter chip, and an ADuM1411 SPI interface isolation chip. The voltage across the precision resistor is followed and processed by the second operational amplifier (TLE2072) before being input to the A / D converter chip. The SPI interface of the A / D converter chip is connected to the ARM chip via the isolation chip. The precision resistor has a resistance of 100Ω. The second operational amplifier acts as a voltage follower.

[0039] like Figure 5 As shown, the compensation circuit consists of a first operational amplifier (TLE2072), a digital potentiometer (CL4801), capacitors, and resistors. The digital potentiometer is connected to the ARM chip via an SPI interface. The CL4801 chip is a 10kΩ digital potentiometer that supports the SPI protocol and has 256 adjustable taps. The digital potentiometer is controlled by the ARM chip to change the compensation circuit's gain. The resistor has a value of 1MΩ. The compensation circuit's gain is controlled within a range of 0 to 1%.

[0040] This example provides a method for transmitting nuclear measurement analog values ​​based on a feedback compensation circuit, including the following steps:

[0041] (1) Initialize the program, initialize each chip, and set the initial resistance of the digital potentiometer to the minimum value;

[0042] (2) In the internal storage module of the ARM chip, the corresponding amplification factors of the first operational amplifier circuit at the 256 tap positions of the digital potentiometer are stored in sequence.

[0043] (3) After converting the nuclear measurement value into 4mA~20mA analog quantity according to the specified range and conversion formula, the output voltage value is obtained and the output of the digital-to-analog converter is controlled;

[0044] (4) Using a feedback circuit composed of precision resistors and A / D conversion chips to measure the error between the output analog quantity and the analog quantity converted by the ARM program;

[0045] (5) If the error exceeds the specified range, the ARM program is used to adjust the tap position of the digital potentiometer, and the compensation circuit composed of the digital potentiometer and the first operational amplifier is controlled by the ARM program to perform real-time compensation on the output current so that the output result meets the technical requirements.

[0046] Those not described in detail in the specification are the prior art known to those skilled in the art.

[0047] It is to be understood that the above description is intended to be illustrative and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reading the above description. The scope of the application should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with their full scope of equivalents.

Claims

1. A method for transmitting nuclear measurement analog quantities based on a feedback compensation circuit, characterized in that: The hardware used in the method includes an ARM chip, a digital-to-analog converter, a digital potentiometer, a first operational amplifier, an isolated voltage-to-current converter, an isolation chip, an A / D conversion chip, a precision resistor, and a second operational amplifier. The ARM chip is respectively connected to the digital-to-analog converter and the digital potentiometer. The ARM chip is connected to the A / D conversion chip after passing through the isolation chip. The first operational amplifier is respectively connected to the digital-to-analog converter, the digital potentiometer, and the isolated voltage-to-current converter. The output current of the isolated voltage-to-current converter is connected to the A / D conversion chip through the precision resistor and the second operational amplifier. The method comprises the following steps: (1) Initialize the program, initialize each chip, and set the initial resistance of the digital potentiometer to the minimum value; (2) When the power is turned on for the first time, the corresponding magnifications of the first operational amplifier circuit at the 256 tap positions of the digital potentiometer are stored in sequence in the internal storage module of the ARM chip. This operation is not required for subsequent work. The specific operation is as follows: (2-1) The ARM chip sets the core measurement analog output current value I to 12mA, the middle value of the current range of 4mA to 20mA. The digital-to-analog converter output voltage value V is converted to 2.5V, the middle value of the voltage range of 0V to 5V, by the corresponding relationship. The conversion formula is: V = (I-4) * 5 / 16; (2-2) Based on the digital-to-analog converter communication protocol, send a command to control the digital-to-analog converter to output a voltage value of 2.5V as the input of the first operational amplifier; measure the voltage value across the precision resistor through the A / D conversion chip, and convert it to obtain the final output analog value; (2-3) Based on the digital potentiometer communication protocol, the ARM chip sends a control command to adjust the resistance value of the digital potentiometer. The command range is 0x00 to 0xFF. 0x00 corresponds to the minimum resistance value, so the first operational amplifier circuit has the minimum amplification factor. 0xFF corresponds to the maximum resistance value, so the first operational amplifier circuit has the maximum amplification factor. (2-4) Compare the output analog value with the set analog value to obtain the system amplification factor. Finally, the ARM chip stores the amplification factors corresponding to the 256 tap positions of the digital potentiometer in the internal storage module; (3) During normal operation, the ARM program uses feedback compensation to correct the output current value; the specific operation is as follows: (3-1) After converting the nuclear measurement value into a 4mA to 20mA analog quantity according to the specified range and conversion formula, the output voltage value is obtained and the output of the digital-to-analog converter is controlled; (3-2) Use the feedback circuit composed of precision resistors and A / D conversion chip to measure the error between the output analog quantity and the analog quantity converted by the ARM program; (3-3) If the error exceeds the specified range, calculate the target amplification factor m = converted analog value a / output analog value b, use the ARM program to query the amplification factor storage array corresponding to the tap position, find the tap position closest to the target amplification factor, write the position into the digital potentiometer, and combine the ARM program to control the compensation circuit composed of the digital potentiometer and the first operational amplifier to perform real-time compensation for the output current.

2. The method for transmitting nuclear measurement analog quantities based on a feedback compensation circuit according to claim 1, characterized in that: The ARM chip uses a GD32F450 chip, and the operating voltage is +3.3V.

3. The method for transmitting nuclear measurement analog quantities based on a feedback compensation circuit according to claim 1, wherein: The current output circuit is composed of a digital-to-analog converter AD5663, a first operational amplifier TLE2072, an isolated voltage-to-current converter 1B22, capacitors, and resistors. The digital-to-analog converter SPI interface is connected to the ARM chip through an isolation chip. The output voltage of the digital-to-analog converter is used as the input of the first operational amplifier; and the output of the first operational amplifier is used as the input of the voltage-to-current converter.

4. The method for transmitting nuclear measurement analog quantities based on a feedback compensation circuit according to claim 1, wherein: The feedback circuit consists of a precision resistor with a tolerance of ±0.01%, a second operational amplifier TLE2072, an A / D conversion chip AD7327, and an SPI interface isolation chip ADuM1411. The voltage across the precision resistor is processed by the second operational amplifier TLE2072 and then input to the A / D conversion chip; the SPI interface of the A / D conversion chip is connected to the ARM chip through the isolation chip.

5. The method for transmitting nuclear measurement analog quantities based on a feedback compensation circuit according to claim 1, wherein: The compensation circuit is composed of a first operational amplifier TLE2072, a digital potentiometer CL4801, a capacitor and a resistor; and the digital potentiometer SPI interface is connected to the ARM chip.

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