Small high-precision PID temperature control system

Abstract

The utility model provides a small-sized high-precision PID (Proportion Integration Differentiation) temperature control system, which belongs to the technical field of electronic control, adopts a three-layer structure and comprises a main control unit positioned on the top layer, a communication unit and an execution unit positioned on the middle layer, and a temperature acquisition unit and a power supply unit positioned on the bottom layer, the temperature acquisition unit converts an analog quantity signal acquired by the PT1000 temperature sensor into a digital quantity signal, and transmits the digital quantity signal to the main control unit through an SPI protocol. And the main control unit calculates a required control signal through a PID algorithm and transmits the control signal to the execution unit. And the execution unit outputs a 24V signal after receiving the control signal of the main control unit. The PID algorithm adopted by the main control unit can shorten the response time of the system, so that the system can quickly reach a steady state, the delay in the adjusting process is reduced, and the system output can be accurately adjusted to quickly approach a target value. The temperature acquisition unit adopts an AD7124-8 chip applied to low-power-consumption and high-precision measurement, and the temperature change can be rapidly and accurately detected.

Description

Technical Field

[0001] This utility model belongs to the field of electronic control technology, and in particular relates to a small, high-precision PID temperature control system. Background Technology

[0002] With the development of technology, temperature control is being used in increasingly diverse applications, such as laboratory temperature control, industrial heating equipment, refrigeration equipment, and temperature management of electronic devices. These applications place high demands on temperature control accuracy, stability, and response speed.

[0003] Traditional temperature control methods often fail to meet the demands of modern applications, such as rapid and convenient installation, high precision, and fast response. Currently, while many temperature control modules can achieve PID control, they still have limitations in terms of miniaturization, low power consumption, and system response speed. The background technology for small, high-precision PID temperature control modules is primarily based on PID control algorithms, and it aims to achieve miniaturization, low power consumption, and fast response while maintaining temperature control accuracy. With increasing demands for temperature control accuracy and growing market demand, this technology has broad application prospects in multiple fields.

[0004] Therefore, there is a need for a temperature control system that can solve the problems of control delay, high energy consumption, and insufficient accuracy that may exist in traditional temperature control systems, and can improve the accuracy, response speed and stability of the temperature control system. Utility Model Content

[0005] The purpose of this utility model is to provide a small, high-precision PID temperature control system, including a base plate with a power supply unit and a temperature acquisition unit, an intermediate plate with a communication unit and an execution unit, and a top plate with a main control unit. The units on the top plate, intermediate plate, and base plate are interconnected by signals.

[0006] The power supply unit is connected to an external power source to power each unit; the temperature acquisition unit includes a chip, which collects signals and transmits them to the main control unit.

[0007] The main control unit is based on the STM32F4 series microcontroller with ARM-M4. It receives data transmitted from the temperature acquisition unit in real time, integrates a PID algorithm, calculates the required control signal through the PID algorithm, and transmits the control signal to the execution unit.

[0008] The temperature control system communicates with the equipment and the host computer through the communication unit. The execution unit receives the control signal and adjusts the power of the heating / cooling equipment according to the output signal to accurately maintain the target temperature.

[0009] Furthermore, the main control unit adjusts the PID parameters via the RS485 serial bus interface, which facilitates the adjustment and optimization of the control effect.

[0010] Furthermore, the temperature acquisition unit adds a differential amplifier, low-pass filter, and protection circuit to the front end of the hardware to avoid external interference affecting signal quality, thereby improving signal acquisition accuracy and signal-to-noise ratio; enhances anti-interference capability by adding a digital filtering system to the MCU software; and achieves high-speed communication by adding an SPI interface.

[0011] Furthermore, the temperature acquisition unit is specifically an RTD signal acquisition circuit based on AD7124-8. The analog signal of the three-wire RTD circuit is acquired and transmitted to the execution unit via the serial interface SPI through digital-to-analog conversion.

[0012] Furthermore, the top plate, bottom plate, and middle plate are integrated into a single housing, which is also equipped with status indicator lights. The main control unit controls the status display of the status indicator lights.

[0013] Furthermore, the communication module uses the SP3485EN-L / TR chip to communicate with the device and the host computer via the Modbus protocol.

[0014] Compared with the prior art, the beneficial effects of this utility model are mainly reflected in:

[0015] 1. The system of this utility model adopts a three-layer PCB high integration design, and the modules are miniaturized and use a general industrial guide rail mounting interface, which occupies little space and is easy to embed into small equipment or complex systems.

[0016] 2. The temperature acquisition unit uses the AD7124-8 chip, which is used for low-power and high-precision measurement applications. It can accurately acquire data from the high-precision temperature sensor PT1000, and can quickly and accurately detect temperature changes, ensuring that the system accuracy reaches ±0.1℃ or higher.

[0017] 3. The PID algorithm used in the main control unit can significantly shorten the system response time, enable the system to quickly reach steady state, reduce the delay in the adjustment process, and accurately adjust the system output to quickly approach the target value.

[0018] 4. The overall design of this utility model of a small high-precision PID temperature control system is an independent module, which facilitates rapid integration into different systems, improves the system's control performance, efficiency, reliability and intelligence level, while reducing energy consumption and operating costs. Attached Figure Description

[0019] Figure 1 This is a system structure diagram of a small, high-precision PID temperature control system according to the present invention.

[0020] Figure 2 This is a flowchart of the PID temperature control method of this utility model.

[0021] Figure 3This is a schematic diagram of the physical structure of this utility model.

[0022] The components include: 1. Top plate; 2. Middle plate; 3. Bottom plate; 4. Main control unit; 5. RS485 communication unit; 6. Execution unit; 7. Temperature acquisition unit; 8. Power supply unit; 9. Status indicator light; 10. 24V power supply; 11. Housing. Detailed Implementation

[0023] The present invention will now be described in more detail with reference to the schematic diagrams, which illustrate preferred embodiments of the present invention. It should be understood that those skilled in the art can modify the present invention as described herein while still achieving the beneficial effects of the present invention. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the present invention.

[0024] like Figure 1 and 3 As shown, a small, high-precision PID temperature control system includes a main control unit 4, an execution unit 6, a temperature acquisition unit 7, a power supply unit 8, and an RS485 communication unit 5. Each unit is integrated into the housing 11 via a layered plate. Specifically, the main control unit 4 is fixed to the top plate 1, the communication unit 5 and the execution unit 6 are fixed to the middle plate 2, and the temperature acquisition unit 7 and the power supply unit 8 are fixed to the bottom plate 3.

[0025] Main control unit 4

[0026] The main control unit (MCU) integrates a PID algorithm, and PID parameters are adjusted via the RS485 serial bus interface, facilitating rapid adjustment and optimization of control performance. Compared to traditional PID algorithms, this method is relatively simple, offers high temperature control accuracy, and requires no complex programming. (Reference) Figure 2 The PID algorithm implementation process is as follows: Initialize data by setting the target temperature value, sampling time, proportional coefficient, and integral coefficient via an external RS485. Obtain the current temperature value from the temperature acquisition unit, perform PID calculation based on the calculated temperature error, adjust the output of the heater or cooler, and output the RS485 control signal. Store the current temperature and error e(t) for the next update. Repeat the acquisition and calculation process. The PID control will continuously update the temperature control until the temperature stabilizes near the set value.

[0027] A status indicator light 9 is also provided on the outside of the housing 11, and the status display of the light is controlled by the main control unit 4.

[0028] RS485 communication unit 5

[0029] RS485 communication unit 5 uses the SP3485EN-L / TR chip, which communicates with devices and host computer software that conform to common fieldbus standards via the Modbus protocol to set PID parameters and output RS485 signals. The reception and transmission of RS485 signals are achieved through timer interrupts.

[0030] Execution Unit 6

[0031] The execution unit 6 is divided into high and low level outputs and RS485 control signal outputs.

[0032] The execution unit 6 receives the control signal output by the main control unit 4 and directly drives and adjusts the power of the heating / cooling equipment by outputting high and low level signals to accurately maintain the target temperature.

[0033] Additionally, the RS485 runs the commonly used serial protocol MODBUS RTU. The master control unit 4 sends commands through a polling mechanism, ensuring a unique response from each device. The calculation result u(t) of the PID algorithm is converted into a digital signal and sent to the execution device via RS485. The execution device parses the received control signal and drives the corresponding temperature adjustment action.

[0034] Temperature acquisition unit 7

[0035] Temperature acquisition unit 7 is an RTD signal acquisition circuit based on AD7124-8. A differential amplifier, low-pass filter, and protection circuits (such as TVS diodes and surge protectors) are added to the front end of the hardware to prevent external interference from affecting signal quality, thereby improving signal acquisition accuracy and signal-to-noise ratio. A digital filtering system is added to the MCU software to enhance anti-interference capabilities, and an SPI interface is added to achieve high-speed communication.

[0036] The temperature acquisition unit 7, which uses the AD7124-8 chip for low-power, high-precision measurement applications, can acquire data from temperature sensors including the PT1000. It converts the analog signals acquired by the PT1000 temperature sensor into digital signals and transmits the digital signals to the main control unit 4 via the SPI protocol.

[0037] Power supply unit 8

[0038] The power supply unit 8 is connected to an external 24V power supply, and the 24V supply provides two independent power supplies to provide working power for the temperature acquisition unit 7 and the main control unit 4.

[0039] This invention uses two ADR4525 chips to generate independent dual-channel reference voltages, combined with optocouplers for isolation. It features two independent input power supplies (temperature acquisition unit 7, main control unit 4) to avoid power interference between different channels, and the two outputs have high electrical isolation, making it suitable for use in high-voltage and harsh environments.

[0040] The workflow of this utility model is as follows:

[0041] Temperature acquisition unit 7 uses an AD7124-8 chip to acquire data from temperature sensors including the PT1000. It converts the analog signals acquired by the PT1000 temperature sensor into digital signals and transmits these digital signals to the main control unit 4 via the SPI protocol. The main control unit 4 calculates the required control signals using a PID algorithm and transmits these signals to the execution unit 6. Upon receiving the control signals from the main control unit 4, the execution unit 6 outputs a 24V signal.

[0042] In addition to the above-mentioned process, this utility model also includes the following basic processes: electrical initialization, software initialization, starting the LED program and executing the Modbus program, which will not be elaborated here.

[0043] The above are merely preferred embodiments of this utility model and do not constitute any limitation on this utility model. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and contents disclosed in this utility model without departing from the scope of the technical solutions of this utility model shall still fall within the protection scope of this utility model.

Claims

1. A small, high-precision PID temperature control system, characterized in that, It includes a base plate for setting up a power supply unit and a temperature acquisition unit, an intermediate plate for setting up a communication unit and an execution unit, and a top plate for setting up a main control unit. The units on the top plate, intermediate plate and base plate are interconnected by signals. The power supply unit is connected to an external power source to supply power to each unit; the temperature acquisition unit includes a chip that acquires signals and transmits them to the main control unit. The main control unit is connected to the temperature acquisition unit and receives data transmitted by the temperature acquisition unit in real time. The main control unit integrates a PID algorithm, which calculates the received data into the control signal required by the execution unit. The temperature control system communicates with the device and the host computer through a communication unit. The execution unit receives control signals and adjusts the power of the heating / cooling equipment according to the output signals to accurately maintain the target temperature.

2. The small, high-precision PID temperature control system according to claim 1, characterized in that, The main control unit adjusts the PID parameters via the RS485 serial bus interface, which facilitates the adjustment and optimization of the control effect.

3. The small, high-precision PID temperature control system according to claim 1, characterized in that, The temperature acquisition unit adds a differential amplifier, low-pass filter, and protection circuit to the front end of the hardware to avoid external interference affecting signal quality, thereby improving signal acquisition accuracy and signal-to-noise ratio; it enhances anti-interference capability by adding a digital filtering system to the MCU software; and it achieves high-speed communication by adding an SPI interface.

4. The small, high-precision PID temperature control system according to claim 3, characterized in that, The temperature acquisition unit is specifically an RTD signal acquisition circuit based on AD7124-8. It acquires the analog signal of the three-wire RTD circuit, converts it to digital-to-analog conversion, and transmits the temperature signal to the execution unit via the serial interface SPI.

5. The small, high-precision PID temperature control system according to claim 1, characterized in that, The top plate, bottom plate, and middle plate are integrated into a single housing. The housing is also equipped with status indicator lights, and the main control unit controls the status display of the status indicator lights.

6. The small, high-precision PID temperature control system according to claim 1, characterized in that, The communication module uses the SP3485EN-L / TR chip and communicates with the device and host computer via the Modbus protocol.

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