Design Of High-precision Thermostatic Bath Based On STM32

With the development of science and technology in our country,the fields of metrology,scientific research,biotechnology and etc.have put forward higher requirements on the temperature environment.The thermostatic bath is required to provide a constant temperature field.The thermostatic bath uses liquid as the heat-conducting medium,through the temperature control system and stirring device,a uniform and stable constant temperature field is formed inside.At present,the common thermostatic baths on the market mainly adopt the structure of electric heating wire as heating device and compressor as refrigeration device.This article uses semiconductor refrigeration technology to replace electric heating wire and compressor,and designs a small size,high performance,low cost,Easy-to-carry thermostatic bath.Firstly,according to the working principle of the thermostatic bath,the overall structure design of the thermostatic bath system was carried out,which mainly includes the bath structure design,the model selection of semiconductor refrigeration chip,the selection of stirring method,the selection of heat insulation material,the heating/refrigeration structure design and the anticorrosion measures,etc.Secondly,according to the control characteristics of the constant temperature bath,the temperature control algorithm of the constant temperature bath was designed.According to the temperature control characteristics of the constant temperature bath,the traditional PID control and neural network PID control algorithm are studied,the thermostatic bath temperature control are implemented using the PID control algorithm based on BP neural network.Completed the hardware circuit and software system design.The hardware circuit of the system takes STM32 as the main control core,the schematic design of the power module,temperature measurement module,heating/refrigeration module,liquid level detection module and human-computer interaction module are completed,drew the PCB circuit board and performed welding and debugging.Completed the hardware platform construction of the temperature control system of the thermostatic bath.Carry on the programming to each function module,use MATLAB to make the upper computer software.After debugging and running,the temperature field stability of the high precision thermostatic bath designed in this paper is ±0.01℃,and the fluctuation is ±0.015℃,which meets the design requirements.