Study on pressure control strategy for a environmental simulation system

A high-altitude multi-parameter environmental simulation system can simulate a high-altitude flying environment for aircraft on ground. It has a very important effect on researching aircraft Environment Control System (ECS) and testing its working performance. However, it is very difficult for a traditional experimental system to realize a pressure decoupling control in a real multi-parameter simulation because the pressure control is strongly coupling with the temperature and humidity control. Therefore, a multi-parameter environmental simulation experiment is not very fast and precise currently. In order to meet the high-altitude experimental requirements, it needs to develop a new experimental method and the corresponding strategy. In this paper, an experimental method is used and it controls the pressure in the environmental simulation cabin only by using an air exhaust valve. Further, a two-degree-of-freedom PID pressure control strategy with a nonlinear compensation is also presented to control the air exhaust valve. The control strategy can realize a pressure decoupling control from the temperature and humidity control. The nonlinear flow character of the air exhaust valve can be compensated by introducing a nonlinear compensation part and the pressure control overshoot can be overcome by the two-degree-of-freedom PID controller. Simulation results show that this presented control strategy can realize a real-time environmental control and improve the control precision and respond speed greatly.