Analysis,Design&Experiments Of Control Strategy For Atmospheric Pressure High&Low Temperature Test System

High and low temperature test system refers to the test or practical system device which can provide suitable target temperature,cooling rate,humidity and pressure environment.As a simulation environment,high and low temperature test system plays an important role in the field of Aeronautics and astronautics.Because of the complexity of the controlled object itself and the high coupling correlation of Engineering requirements,the development of automatic control system is difficult and the practical reliability is low.Therefore,manual control is still the main control mode for large-scale high and low temperature systems.Because of the shortcomings of manual control,such as low control precision,high requirement for operator's experience and long working time,in order to meet the need of high-precision temperature control in large temperature range of high and low temperature test system,reliable and effective automatic control system is urgently needed.Firstly,the control characteristics of the high and low temperature test system under different operating conditions are analyzed,and the control response characteristics of the system under different operating conditions are obtained.In this paper,a multi-level fuzzy control strategy is designed for the displacement process.At the same time,in the low and high temperature process,a fuzzy-PID controller is designed by combining the traditional PID control method with the fuzzy control method.Then,the dynamic distributed parameter model of the system is established based on the hydrothermal dynamics,and the joint dynamic simulation with the designed control strategy is carried out to preliminarily verify the effectiveness and feasibility of the control strategy.Finally,with PLC-Labview as the control hardware,the control strategy algorithm is implemented on the ground,and the multi-condition flow is verified by experiments.The experimental results show that the control strategy designed in this paper has remarkable excellent control effect for the high and low temperature test system.