FPGA-based multi-channel thermocouple temperature measurement system

Abstract

Aiming at the high and low temperature test requirements of spacecraft before being sent into space, this paper designs and implements a multi-channel thermocouple temperature measurement system based on FPGA.The system adopts thermocouple as temperature sensor, and ADT7310 is used as thermocouple cold junction temperature compensation, which solves the problem of thermocouple cold junction compensation better.The front end adopts AD7193, a 24-bit analog-to-digital converter with low noise, multi-channel and low power consumption, to amplify and A/D convert the signal at measuring junction of thermocouple.The control core is a field programmable logic gate array FPGA, which can better solve the problem of parallel processing of multi-channel temperature signals. At the same time, it uses the transposition method of the thermocouple standard graduation table, the interpolation look-up table algorithm and the cold junction compensation reverse look-up table algorithm, which is effective The temperature measurement accuracy of each channel is improved.The experimental results show that the system can be connected to 24 K-type or T-type thermocouple sensors, the measurement range can reach -200°C∼220°C (73.15K∼493.15K), and the relative error is less than ±0.3%F.S.