A thermistor testing system

Abstract

The utility model relates to resistance test technical field, and disclose a thermistor test system, including temperature control module and digital analog conversion module, temperature control module is heating cooling platform, temperature sensor, relay and singlechip development board constitute closed loop temperature control system, digital analog conversion module is analog digital converter and development board links, and the accurate measurement of thermistor value is realized to cooperation standard pull -up resistance. Through PC end control program realizes temperature setting, data acquisition and processing, can automatically complete thermistor's temperature - resistance characteristic curve test. The utility model adopts modularization design, can realize real -time temperature and resistance measurement, has promoted test efficiency and precision, is suitable for thermistor's semi -automatic test.

Description

Technical Field

[0001] This utility model relates to the field of resistance testing technology, specifically to a thermistor testing system. Background Technology

[0002] As an important temperature-sensitive element, the thermistor's resistance value decreases or increases exponentially with increasing temperature, and it is widely used in temperature measurement, temperature compensation, surge suppression and other fields.

[0003] Traditional thermistor testing methods often employ constant-temperature oil baths or ovens combined with multimeters or resistance meters, which suffer from low temperature control accuracy, poor testing efficiency, and cumbersome manual operation. Existing automated testing systems are often complex in structure, expensive, and struggle to achieve rapid temperature switching and high-precision data acquisition. Therefore, there is an urgent need to develop a thermistor testing system that is simple in structure, low in cost, and capable of high-precision semi-automated testing. Utility Model Content

[0004] To address the challenges of existing technologies, this utility model provides a thermistor testing system that solves the problems of traditional thermistor testing, offering the following technical solution: A thermistor testing system, mainly comprising the following two modules:

[0005] Temperature control module: It includes a closed-loop temperature control system consisting of a heating and cooling platform, a temperature sensor, a relay, and a microcontroller development board. The temperature sensor is connected to the microcontroller development board through series resistors.

[0006] The analog-to-digital converter module includes an analog-to-digital converter and a measurement circuit composed of resistive components. The thermistor and the resistive components form a voltage divider circuit that is connected to the analog-to-digital converter. The analog-to-digital converter and the microcontroller development board are connected to form a signal transmission system.

[0007] As a preferred embodiment of this utility model, the temperature control module is electrically connected to the digital-to-analog converter module through its internal microcontroller development board, and communicates with the PC computer for data and power supply through the USB interface of the microcontroller development board. Software code is written to implement temperature control commands and collect and process measurement data.

[0008] As a preferred embodiment of this utility model, the analog-to-digital converter has a resolution of 6-24 bits. For smaller measurement errors, a 24-bit analog-to-digital converter is preferred. The analog-to-digital converter must include at least an analog input channel, an analog power supply channel, an analog ground channel, a digital input clock signal, and digital input / output signals.

[0009] In a preferred embodiment of this utility model, the temperature sensor has a resolution of 9-12 bits; for higher detection accuracy, a 12-bit temperature sensor is preferred. The temperature sensor includes a power line, a signal line, and a ground line, thereby improving the temperature sensor's anti-interference capability.

[0010] Preferably, the heating and cooling platform 2 is connected to the microcontroller development board 8 via a relay 6 to form a programmable temperature control loop. Its operating power is supplied by an independent power adapter, and the on / off control is achieved through the relay 6.

[0011] Preferably, the temperature sensor 4 is a digital temperature sensor that communicates with the microcontroller development board 8 via a single-bus protocol, and a resistor 5 is connected in series on the signal line.

[0012] Preferably, the resistance value of the resistive component 5 is matched with the nominal resistance value of the thermistor 3 to form a proportional measurement circuit.

[0013] Preferably, the analog-to-digital converter 9 is connected to the microcontroller development board 8.

[0014] Preferably, the thermistor can be an NTC type thermistor or a PTC type thermistor.

[0015] Preferably, the resistance values ​​of the multiple resistive components can be the same or different, and the specific resistance values ​​can be set differently according to the circuit design requirements.

[0016] In summary, the embodiments of this utility model have the following beneficial effects: the modular design of the temperature control module and the digital-to-analog converter makes the testing structure of the thermistor testing system simple, convenient, easy to build, and low in cost; the combination of the high-precision temperature sensor in the temperature control module and the high-resolution analog-to-digital converter in the digital-to-analog converter module makes the temperature control accuracy of the thermistor testing system higher; the microcontroller development board controls the temperature of the heating and cooling stage and reads the test data of the sample in real time through software program, which has high testing efficiency, realizes semi-automatic testing, and has broad market prospects. Attached Figure Description

[0017] Figure 1 A schematic diagram of a thermistor testing system provided in this embodiment of the utility model;

[0018] Figure 2 The device of this embodiment of the invention is used to test the temperature-resistance curve of a 100kΩ standard thermistor at room temperature;

[0019] Figure 3 The device of this embodiment of the invention is used to test the temperature-resistance curve of a 50kΩ standard thermistor at room temperature;

[0020] Figure 4 The device of this embodiment of the invention is used to test the temperature-resistance curve of a 10kΩ standard thermistor at room temperature;

[0021] The components include: 1. Temperature control module; 2. Heating and cooling platform; 3. Thermistor; 4. Temperature sensor; 5. Resistive components; 6. Relay; 7. Digital-to-analog converter module; 8. Microcontroller development board; and 9. Analog-to-digital converter. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model are described clearly and completely below in conjunction with specific embodiments. It should be understood that the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the protection scope of this utility model.

[0023] Example 1:

[0024] A testing system for thermistors, with the following specific operating steps:

[0025] The temperature control module 1 includes a heating and cooling platform 2 consisting of a heating plate and a cooling fan. The heating plate and cooling fan operate at 12V, with a maximum temperature of 270℃ and a fan speed of 2300–3500 r / min. The module also includes a DS18B20 digital temperature sensor 4, operating at 3.0–5.5V, with a sensing range of -55–125℃. Its three leads are ground (GND), signal (DATA), and power (VCC). A single-phase solid-state SSR-25DD relay 6, a DC-controlled DC type, operates at 4–32V input, 5–120V output, and has a load current of 25A. This, along with an Arduino UNO R4 microcontroller development board 8 (operating at 5V), forms a closed-loop temperature control system with numerous pins. To ensure good thermal conductivity between the heating platform, NTC thermistor, and temperature sensor probe, a non-curing, high-thermal-conductivity gel is used to fill the gaps and bond them tightly together. Furthermore, the thermistor and temperature sensor probe must be mounted coplanarly to ensure consistent temperatures. The digital-to-analog converter module 7 includes an ADS1115 analog-to-digital converter 9 with a resolution of 16 bits, an operating voltage of 2.0 to 5.5V, and a voltage range of -4.096 to +4.096V; a measurement circuit composed of resistors of different resistance values ​​5, used to suppress interference and protect circuit components; and a digital-to-analog conversion system formed with the Arduino UNO R4 microcontroller development board 8, which operates at 5V and has numerous pins.

[0026] The Arduino UNO R4 microcontroller development board 8 communicates with a PC via USB. Software code is written to send temperature control commands to the heating / cooling platform 2. The Arduino UNO R4 microcontroller development board 8 collects and processes measurement data from temperature sensor 4 and ADS1115. The collected temperature is recorded, and the temperature accuracy is controlled within ±0.5℃. The values ​​collected by ADS1115 are converted using the following formula:

[0027]

[0028] The corresponding temperature and resistance values ​​are obtained. Where R... NTC The resistance value of NTC thermistor 3 is shown in the figure. ADS represents the measurement data from the ADS1115. (V) s R is the supply voltage for the circuit. s This is the resistance value of resistor component 5.

[0029] After the above test system is constructed, it should be noted that the resistor 5 connected in series with the NTC thermistor should be selected with a resistance value close to 0.8 to 1.2 times that of the thermistor at room temperature. For hardware connection, connect a commercially available 100±1%kΩ standard NTC thermistor 3 in series with the 100kΩ resistor 5, supplying a voltage of 3.3V, and simultaneously connecting it to pin A0 of the ADS1115 analog-to-digital converter 9. See the circuit connection diagram below. Figure 1 .

[0030] Then the testing procedure was carried out: ① The step temperature rise range was 30℃~110℃; ② The resistance value was recorded every 5℃, for a total of 17 data points; ③ As Figure 2 As shown, temperature and resistance values ​​were obtained by converting measured data and fitting an RT curve. The temperature coefficient B was then calculated to be 3995K, with an error of 1.14% compared to the nominal 3950K.

[0031] Example 2:

[0032] A testing system for thermistors is the same as in Example 1, except that the specific operating steps are as follows:

[0033] The test system is constructed as in Example 1. Hardware connections are made by connecting a commercially available 50±1%kΩ standard NTC thermistor 3 in series with a 50kΩ resistor 5, and simultaneously connecting it to the A0 pin of the ADS1115 analog-to-digital converter 9.

[0034] Then the testing procedure was carried out: ① The step temperature rise range was 30℃~110℃; ② The resistance value was recorded every 5℃, for a total of 17 data points; ③ As Figure 3As shown, temperature and resistance values ​​were obtained by converting measured data and fitting an RT curve. The temperature coefficient B was then calculated to be 3957 K, with an error of 0.18% compared to the nominal 3950 K.

[0035] Example 3:

[0036] A testing system for thermistors is the same as in Example 1, except that the specific operating steps are as follows:

[0037] The test system is constructed as in Example 1. Hardware connections are made by connecting a commercially available 10±1%kΩ standard NTC thermistor 3 in series with a 10kΩ resistor 5, and simultaneously connecting it to the A0 pin of the ADS1115 analog-to-digital converter 9.

[0038] Then the testing procedure was carried out: ① The step temperature rise range was 30℃~110℃; ② The resistance value was recorded every 5℃, for a total of 17 data points; ③ As Figure 4 As shown, temperature and resistance values ​​were obtained by converting measured data and fitting an RT curve. The temperature coefficient B was then calculated to be 3908 K, with an error of 1.06% compared to the nominal 3950 K.

[0039] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions all fall within the protection scope of this utility model, and as long as they do not depart from the spirit and essence of the technical solutions of this utility model, they should be covered within the scope of the claims of this utility model.

Claims

1. A thermistor testing system, characterized in that, include: Temperature control module (1): includes a closed-loop temperature control system consisting of a heating and cooling platform (2), a temperature sensor (4), a relay (6) and a microcontroller development board (8), wherein the temperature sensor (4) is connected to the microcontroller development board (8) through a series resistor (5); The analog-to-digital converter module (7) includes an analog-to-digital converter (9) and a measurement circuit composed of resistive components (5). The thermistor (3) and the resistive components (5) form a voltage divider circuit connected to the analog-to-digital converter. The microcontroller development board (8) is electrically connected to the temperature control module (1) and the digital-to-analog converter module (7) respectively, and communicates with the PC via the USB interface to send temperature control commands to the heating and cooling platform (2), and collects and processes the measurement data of the temperature sensor (4) and the analog-to-digital converter (9).

2. The thermistor testing system according to claim 1, characterized in that, The heating and cooling platform (2) is connected to the microcontroller development board (8) via a relay (6) to form a programmable temperature control loop. Its working power is supplied by an independent power adapter, and the on / off control is achieved through the relay (6).

3. The thermistor testing system according to claim 1, characterized in that, The temperature sensor (4) is a digital temperature sensor that communicates with the microcontroller development board (8) via a single-bus protocol, and a resistor (5) is connected in series on the signal line.

4. The thermistor testing system according to claim 1, characterized in that, The resistance value of the resistive component (5) is matched with the nominal resistance value of the thermistor (3) to form a proportional measurement circuit.

5. The thermistor testing system according to claim 1, characterized in that, The analog-to-digital converter (9) is connected to the microcontroller development board (8).

6. The thermistor testing system according to claim 1, characterized in that, The microcontroller development board (8) is connected to a PC via a data transmission line. The PC runs test software and can display the temperature-resistance curve in real time.

Images