Abstract:In view of nonliner,time-delay of controlled object in a temperature control system for environment simulation test, theSrange limit PIDScontrol algorithm and fuzzy PID control algorithm is adopted to improve the traditional control method in this paper. Firstly, in order to solve the disadvantage of tardiness for Analog tee coarse adjustment valve,controlSregulation table of theSrange limit PIDScontrol algorithmSis established, then the algorithm is implemented in PLC.Then the method of using fuzzy PID control algorithm to solve nonliner, time-delay of electrical heater is proposed, the fuzzy controlSregulation table is established after combining with the actual control experience,thenthe fuzzy PID control algorithm is implemented in PLC. Finally, theSrange limit PIDScontrol algorithm and fuzzy PID control algorithm is applied to a large environmental simulation test control system,the experimental results show that it has a good stability and accuracy.