Design And Realization Of High Precision Thermostat Bath Temperature Control System

As control system,temperature control has become more and more common in the field of automatic control and high-precision thermostatic control is needed in medical,chemical and biological fields.Therefore,the thermostatic control system with high precision,high stability,simple structure,simple operation and low cost has a bright market prospect.Compared with the domestic temperature control equipment,the system has the advantages of low cost,high precision of temperature measurement and high precision of temperature control.The system is divided into temperature acquisition and processing,human-computer interface design,communication interface design,and software drivers.With ATmega16 used as the core controller in the temperature acquisition circuit,the system uses PT1000 sensor to collect water temperature and partial PT1000 voltage across the acquisition to achieve high-precision temperature measurement and temperature control.In order to ensure the acquisition accuracy,the system uses Low temperature coefficient of drift,high precision precision resistors as a divided resistor.With data collected by a 24-bit ADC and the digital value of the voltage across the sensor transmitted to the microcontroller,a high-precision real-time temperature is obtained by a linear fitting method.The system use STM32 as the controller to complete the data further processing and it mainly use the collected site temperature as a benchmark with the STM32 preset target temperature difference,real-time PID to adjust the difference.The temperature control is performed by controlling the proportion of the power supply time within a certain period of time.Through the output in the heating cycle,the proportion of high-level pulse to control the solid state relay on-time,and then it control the heating wire heating power,and ultimately achieve constant temperature control.?C / OS-III is embedded in the software,and the multi-tasking design method is used to complete the drive control of each function module.Man-machine interface mainly uses Wei Lun Tong industrial screen,the main real-time temperature information display and proportion,integral,differential coefficient settings.It's display interface is intuitive and clear and it has good operability.The system is mainly designed two serial communication interface to complete the touch screen with STM32,STM32 with temperature acquisition circuit communication.The subject completed the expected goal well and made a prototype.The system temperature measurement accuracy up to ±0.002? and-5?~ 40 ? temperature range can reach the control accuracy ±0.005? index.