The Design Of A Thermal Control Unit On A Spacecraftbased Embedding Technologyand Fieldbus

In a spacecraft, the thermal control subsystem is in charge of controlling the temperature of other devices. Nowdays, there are mainly two kinds of thermal control technology, passive technology and active technology, in which, active electric heating technology is realized by thermal control unit.According to the requirement of collecting temperature data, controlling heaters and data communication, this paper elaborates the design of a thermal control unit, which is based on MCS-51 and Fieldbus CAN. In order to mesure temperature, the design adopts the sampling circuit made up of operational amplifier and A/D converter, and import the error correcting theory. For the different requirement of heaters, the paper designs electric switches and mechanical switches, and discusses the controlling flow of the two switches. For the purpose of data communication, the paper lodges the CAN interface circuit, and expatiates the programs of bus initialization, bus interrupt service routing, receiving and sending bus data. Furthermore, this paper probes into the methods of reliability in the circuit and programs. With the structural layout of reliability and mathematical models, the paper evaluates the reliability of the design, and adopts a series of experiments to prove the reiability. In conclusion, the effect of a thermal control unit on a spacecraft is given.The achievement and significance of the research is that the thermal control unit can collect the temperature of every device on a spacecraft accurately, meet with the different requirement of heaters, and realize the rapid and reliable data communication in the complex space environment.