Thermal resistor simulation device and calibration method

Abstract

The invention relates to the technical field of temperature sensors, and discloses a thermal resistor simulation device and a calibration method.The thermal resistor simulation device comprises a main control chip, the main control chip is connected with a power supply control module, a digital potentiometer and a fixed value resistor, and the main control chip controls the power supply control module and the digital potentiometer; the power supply control module is respectively connected with an external voltage-stabilized power supply and a vernier end of the digital potentiometer, and one end, connected with the main control chip, of the fixed value resistor is connected with a low potential end of the digital potentiometer at the same time. The other end of the fixed value resistor and the vernier end of the digital potentiometer are respectively an analog output end; the resistance value adjustable range is wide, automatic calibration is achieved, the circuit is simple, and the structure is compact.

Description

Technical Field

[0001] This application relates to the field of temperature sensor technology, specifically to a resistance temperature detector (RTD) simulation device and calibration method. Background Technology

[0002] The PT1000 is a resistance temperature detector (RTD) whose resistance increases with temperature. The PT1000 has a resistance of 1000Ω at 0℃, 921.599Ω at -20℃, and 1385.055Ω at 100℃. Its measurement range is between -50℃ and 300℃.

[0003] The axle temperature alarm in railway passenger cars often uses a composite temperature sensor to collect the bearing temperature. The composite temperature sensor includes an analog temperature sensor and a digital temperature sensor, among which the PT1000 is used as the analog temperature sensor.

[0004] Since it is difficult to achieve temperatures above 100℃ and below -20℃ in the shaft temperature alarm test environment, a digital potentiometer is used to simulate the resistance value of PT1000 at temperatures above 100℃ and below -20℃, thereby replacing the simulated temperature sensor PT1000 to complete the shaft temperature alarm test within the measurement range of PT1000 platinum resistance thermometer.

[0005] Due to manufacturing processes limitations, digital potentiometers may have inherent deviations in their full-scale resistance values. If not calibrated before use, these deviations can lead to significant errors during operation, causing the actual output resistance value of the digital potentiometer to differ from the expected value. Summary of the Invention

[0006] The purpose of this application is to provide a resistance temperature detector (RTD) simulation device and calibration method with a wide adjustable resistance range, automatic calibration, simple circuit, and compact structure.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: The present invention discloses a resistance temperature detector (RTD) simulation device and calibration method, comprising a main control chip, wherein the main control chip is connected to a power control module, a digital potentiometer, and a fixed resistor. The main control chip controls the power control module and the digital potentiometer, and simultaneously samples and analyzes the resistance of the digital potentiometer. The power control module is connected to an external regulated power supply and the vernier terminal of the digital potentiometer. One end of the fixed resistor connected to the main control chip is also connected to the low potential terminal of the digital potentiometer. The other end of the fixed resistor and the vernier terminal of the digital potentiometer are analog output terminals, respectively.

[0008] Furthermore, the power control module is a relay.

[0009] Furthermore, there are multiple power control modules, and multiple I / O ports of the main control chip are respectively connected to the control terminals of multiple power control modules. All multiple power control modules are connected to the external regulated power supply. The number of vernier terminals of the digital potentiometer matches the number of power control modules, and the vernier terminals of the digital potentiometer are respectively connected to the corresponding power control module.

[0010] Furthermore, there are multiple digital potentiometers and multiple fixed resistors, the number of digital potentiometers matches the number of fixed resistors, and each of the multiple digital potentiometers is connected to a corresponding fixed resistor.

[0011] A calibration method for a resistance temperature detector (RTD) simulation device includes the following steps: S1. The power control module is connected to an external regulated power supply, and the thermal resistance simulation device is connected to the power supply. The main control chip outputs an on control signal to the power control module to enable the power control module to connect. S2. The main control chip controls the digital potentiometer to adjust to the minimum resistance value and samples it; according to the circuit series voltage division principle, the main control chip calculates the internal resistance value of the digital potentiometer. S3. The main control chip controls the digital potentiometer to adjust to the full-scale resistance value and samples it; according to the circuit series voltage divider principle, the main control chip calculates the full-scale resistance value of the digital potentiometer. S4. Calculate the unit resistance change value of the digital potentiometer based on its full-scale resistance value, internal resistance value, and maximum order. S5. The main control chip outputs a shutdown control signal to the power control module to disconnect the power control module. S6. Based on the unit change resistance and internal resistance of the digital potentiometer, the resistance change per degree Celsius of the thermal resistor, and the resistance of the fixed resistor, the relationship between the resistance and temperature of the analog device is obtained.

[0012] Compared with the prior art, the beneficial effects of this application are: This invention enables a digital potentiometer to accurately simulate the function of a PT1000 platinum resistance thermometer by controlling the digital potentiometer to use different orders. The invention features a wide adjustable resistance range, automatic calibration, a simple circuit, and a compact structure. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the overall circuit of Embodiment 1 of the present invention.

[0015] Figure 2 This is a schematic diagram of the overall circuit of Embodiment 2 of the present invention.

[0016] Figure 3 This is a schematic diagram of the overall circuit of Embodiment 3 of the present invention.

[0017] Figure 4 This is a flowchart of the method of the present invention.

[0018] Figure 5 This is a schematic diagram showing the connection of ports 8 and 9 of the relay of the present invention.

[0019] Figure 6 This is a schematic diagram showing the relay ports 8 and 9 disconnected according to the present invention. Detailed Implementation

[0020] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0021] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the layers related to the present invention and are not drawn according to the actual number, shape and size of the layers in the actual implementation. In the actual implementation, the shape, number and proportion of each layer can be arbitrarily changed, and the layer layout may also be more complex.

[0022] Numerous details are explored in the following description to provide a more thorough explanation of embodiments of the invention; however, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. Specific Implementation Method 1 Please see Figure 1A resistance temperature detector (RTD) simulation device includes a main control chip, which is connected to a power control module, a digital potentiometer, and a fixed resistor. The main control chip controls the power control module and the digital potentiometer, and samples and analyzes the resistance of the digital potentiometer. The power control module is connected to an external regulated power supply and the vernier terminal of the digital potentiometer. One end of the fixed resistor is connected to the main control chip and also to the low potential terminal of the digital potentiometer. The other end of the fixed resistor and the vernier terminal of the digital potentiometer are analog output terminals, forming an analog output terminal group.

[0024] The main control chip's IIC port is connected to the digital control terminal of the digital potentiometer, outputting an adjustment control signal to the potentiometer. The main control chip's ADC is connected to one end of a fixed resistor and the low-potential terminal of the digital potentiometer, acquiring the resistance value between the low-potential terminal and the vernier terminal of the potentiometer. The vernier terminal of the digital potentiometer is connected to pin 9 of the power control module, serving as an analog output terminal. The fixed resistor connected to ground serves as another analog output terminal, simulating the RTD (Resistor of Temperature). Pin 8 of the power control module is connected to an external regulated power supply, and pin 12 of the power control module is connected to the main control chip's I / O port, outputting control signals to control the on / off state of the power control module. The power control module uses a TX2-3V relay. Specific Implementation Method Two Please see Figure 2 Based on Implementation Method 1, there are multiple power control modules. Multiple I / O ports of the main control chip are connected to the control terminals of each power control module. All power control modules are connected to an external regulated power supply. The multiple I / O ports of the main control chip control the on / off state of their respective power control modules. The number of vernier terminals of the digital potentiometers matches the number of power control modules, and each vernier terminal is connected to a corresponding power control module, expanding to a corresponding number of analog output terminals. These output terminals are then combined with a fixed resistor and ground to form a corresponding number of analog output terminal groups, enabling the simultaneous simulation of multiple thermistors.

[0026] The main control chip is an STM32 microcontroller, and the digital potentiometer uses an AD5254 digital potentiometer chip, which has four independent resistor output terminals, meaning it can simulate four RTDs (Resistors of Resistance). The digital potentiometer has a maximum order of 256 and a maximum output resistance of 1kΩ. The fixed resistor has a resistance of 700Ω. Specific Implementation Method 3 Please see Figure 3 Based on Implementation Method Two, multiple digital potentiometers and fixed resistors are used, with the number of digital potentiometers matching the number of fixed resistors, and each digital potentiometer connected to a corresponding fixed resistor. This expands to include multiples of analog output terminals, enabling the simulation of multiple thermal resistors.

[0028] This invention enables a digital potentiometer to accurately simulate the function of a PT1000 platinum resistance thermometer by controlling the digital potentiometer to use different orders. The invention features a wide adjustable resistance range, automatic calibration, a simple circuit, and a compact structure.

[0029] Please see Figure 4 A calibration method for a resistance temperature detector (RTD) simulation device includes the following steps: S1. The power control module is connected to an external regulated power supply, and the thermal resistance simulation device is connected to the power supply. The main control chip outputs an on control signal to the power control module to enable the power control module to connect. The power control module's 8th port is connected to an external regulated power supply, and the RTD simulation device is connected to the power supply. The main control chip sends control signals through its I / O ports to connect the 8th and 9th ports of the power control module, such as... Figure 5 .

[0030] S2. The main control chip controls the digital potentiometer to adjust to the minimum resistance value and samples it; based on the series voltage divider principle, the main control chip calculates the internal resistance value of the digital potentiometer. ; The main control chip transmits adjustment control signals to the digital potentiometer via the IIC port, causing the vernier terminal of the digital potentiometer to output the minimum resistance value, which is then sampled through the ADC port of the main control chip. The main control chip then calculates the internal resistance value between the low-potential terminal and the vernier terminal of the digital potentiometer. .

[0031] S3. The main control chip controls the digital potentiometer to adjust to the full-scale resistance value, and samples the value. Based on the series voltage divider principle, the main control chip calculates the full-scale resistance value of the digital potentiometer. ; The main control chip transmits adjustment control signals to the digital potentiometer via the IIC port, causing the digital potentiometer's vernier terminal to output a full-scale resistance value, which is then sampled by the main control chip's ADC port. The main control chip then calculates the full-scale resistance value between the digital potentiometer's low-potential terminal and the vernier terminal. .

[0032] S4. Calculate the unit resistance change value of the digital potentiometer based on its full-scale resistance value, internal resistance value, and maximum order. The full-scale resistance value of the digital potentiometer Subtract the internal resistance of the digital potentiometer The maximum change in resistance between the low-potential terminal and the vernier terminal of the digital potentiometer is obtained. ; Set the maximum change in resistance value of the digital potentiometer Divide by the maximum order N of the digital potentiometer to obtain the unit resistance change value of the digital potentiometer. .

[0033] S5. The main control chip outputs a shutdown control signal to the power control module to disconnect the power control module. The main control chip sends a shutdown control signal through the I / O port to disconnect ports 8 and 9 of the power control module, such as... Figure 6 .

[0034] S6. Based on the unit change resistance and internal resistance of the digital potentiometer, the resistance change per degree Celsius of the thermal resistor, and the resistance of the fixed resistor, the relationship between the resistance and temperature of the analog device is obtained.

[0035] Based on the unit resistance change, internal resistance, and fixed resistor value of the digital potentiometer, the formula is used... The resistance value of the thermal resistance simulation device was calculated; among which, The resistance value of the fixed resistor can be 700Ω; The order of the digital potentiometer; according to the formula The relationship between the resistance and temperature of the simulation device was obtained: ;in, is the resistance value per degree Celsius change of the thermal resistor, and N is the maximum order of the digital potentiometer, which is 256 in this invention.

[0036] This invention can accurately simulate a PT1000 platinum resistance thermometer. The minimum temperature change of the digital potentiometer can reach 0.8℃, and the maximum temperature change can reach 1.2℃. This invention has high precision, a wide adjustable range, and automatic calibration.

[0037] This invention obtains the internal resistance and full-scale resistance of a digital potentiometer by adjusting its minimum and maximum output resistance values. From this, the range of resistance variation can be determined. Furthermore, based on the maximum order of the digital potentiometer, the unit resistance change can be accurately calculated. By controlling the digital potentiometer to use different orders, the function of accurately simulating a PT1000 platinum resistance thermometer can be achieved. This invention offers high precision, a wide adjustable resistance range, automatic calibration, a simple circuit, and a compact structure.

[0038] In the above embodiments, although the invention has been described in conjunction with specific embodiments thereof, many substitutions, modifications, and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. The embodiments of the invention are intended to cover all such substitutions, modifications, and variations falling within the broad scope of the appended claims.

[0039] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A resistance temperature detector (RTD) simulation device, characterized in that: The system includes a main control chip, which is connected to a power control module, a digital potentiometer, and a fixed resistor. The main control chip controls the power control module and the digital potentiometer, and samples and analyzes the resistance of the digital potentiometer. The power control module is connected to an external regulated power supply and the vernier terminal of the digital potentiometer. One end of the fixed resistor connected to the main control chip is also connected to the low-potential terminal of the digital potentiometer. The other end of the fixed resistor and the vernier terminal of the digital potentiometer are analog output terminals.

2. The resistance temperature detector (RTD) simulation device according to claim 1, characterized in that, The power control module is a relay.

3. The resistance temperature detector (RTD) simulation device according to claim 1, characterized in that, There are multiple power control modules. Multiple I / O ports of the main control chip are respectively connected to the control terminals of multiple power control modules. All multiple power control modules are connected to the external regulated power supply. The number of vernier terminals of the digital potentiometers matches the number of power control modules, and the vernier terminals of the digital potentiometers are respectively connected to the corresponding power control modules.

4. The resistance temperature detector (RTD) simulation device and calibration method according to claim 3, characterized in that, There are multiple digital potentiometers and multiple fixed resistors. The number of digital potentiometers matches the number of fixed resistors, and each of the multiple digital potentiometers is connected to a corresponding fixed resistor.

5. A calibration method for a resistance temperature detector (RTD) simulation device, characterized in that, Includes the following steps: S1. The power control module is connected to an external regulated power supply, and the thermal resistance simulation device is connected to the power supply. The main control chip outputs an on control signal to the power control module to enable the power control module to connect. S2. The main control chip controls the digital potentiometer to adjust to the minimum resistance value and samples it; according to the circuit series voltage division principle, the main control chip calculates the internal resistance value of the digital potentiometer. S3. The main control chip controls the digital potentiometer to adjust to the full-scale resistance value and samples it; according to the circuit series voltage divider principle, the main control chip calculates the full-scale resistance value of the digital potentiometer. S4. Calculate the unit resistance change value of the digital potentiometer based on its full-scale resistance value, internal resistance value, and maximum order. S5. The main control chip outputs a shutdown control signal to the power control module to disconnect the power control module. S6. Based on the unit change resistance and internal resistance of the digital potentiometer, the resistance change per degree Celsius of the thermal resistor, and the resistance of the fixed resistor, the relationship between the resistance and temperature of the analog device is obtained.

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