High Precision Temperature Measurement And Control Design

High precision temperature measure and control system has been applied extensively in industry and human daily life, especially in the some special experiment environment which need construct specific temperature environment. In order to meet the over demands, we design this system. The system use PT100 thermal resistance as temperature sensor. We design a current source in the system which output 1MA current through PT100. By measuring voltage between the PT100, system can obtain the environment temperature.The system using differential PID algorithm can own the high precision control temperature. The custom can operate this system easily via its friendly display interface. Compared with the general measure and control temperature equipment on the market, the system we design has higher precision temperature measurement and control.Besides the temperature measurement and control, the system also has function of data collection, data communication, data process and data display. As for the PT100 with small voltage signal, we have to design amplifying circuit to match ADC operate range. We select a high precision 24 bits ADC to convert the analog voltage signal from the output port of amplifying circuit unit. The board processor receives and deals the data from ADC.It also can transfer the collection data to PC by USB port. In order to meeting the demand of multiple specific temperature, the system also has two USART to communicate with other board.We design Ethernet on the PCB board for the further upgrade in the future.After system debug, the accuracy of the system temperature measurement can reach ±0.001 Celsius from -40 Celsius to 400 Celsius. The accuracy of the system temperature control can reach±0.02Celsius from -40 Celsius to80 Celsius.