Fuzzy-Pi Control Applied To Thermal Control System in Manned Spacecraft

The temperature control and check valve (TCCV) in a condensing heat exchanger (CHX) controls the amount of atmosphere that flows through or around the CHX depending on the amount of cooling required. This paper presents a new control scheme based on a Fuzzy-PI algorithm to control the CHX. It is realized by the application of Fuzzy-PI controller to the TCCV. The algorithm uses instantaneous and longer-term changes in measured temperature to continually adjust the TCCV position and maintain the atmospheric temperature within specified limits. There is a control threshold switching between PI and Fuzzy control. When the absolute error is higher than the threshold fuzzy control is used, otherwise PI control is used. Simulation is conducted, whose results show that the proposed control scheme makes it possible to improve temperature stability and control precision.