System Simulation And Experiment Study On High Precision Temperature Control Of Mechanical Cryocooler

With the continuous development of the space detection technology,space equipment has higher and higher requirements on the environment.Mechanical cryocooler is widely used in infrared detection technology to improve chip stability and extend the life of the chip,due to their small size,light weight and high stability.Since the infrared camera is very sensitive to the ambient temperature,when the ambient temperature fluctuates beyond a certain range,the imaging quality of the camera is affected.In the new generation of Fengyun satellite photoelectric load,the stability requirement of 50mK(±25mK)is proposed for the low temperature operating temperature of the infrared detector.Therefore,the cold head temperature of the mechanical refrigerator is required to maintain high precision and high stability.In response to these problems,this paper studies the temperature control characteristics of mechanical cryocooler in the following aspects:Firstly,introducing the working principle of the pulse tube type mechanical cryocooler.The components of the mechanical cryocooler temperature control system are described in detail.Analyzing the mathematical models of the drive control circuit and the cryocooler components.Then the two are combined to summarize the model of the mechanical cryocooler temperature control system.Secondly,the temperature control algorithm of the mechanical cryocooler is studied.The influence of the positional PID algorithm and the incremental PID algorithm on the performance of the mechanical cryocooler system is summarized.Combined with the performance characteristics of the mechanical cryocooler,the simplified stability domain parameter range is given.The calculation method makes the parameter setting of the control algorithm more concise and understandable.Thirdly,based on the multi-physics domain simulation software-Simplorer software,combined with the compressor simulation software-Maxwell software and control system and Dewar component simulation software-Simulink/Matlab software,the simulation platform of the mechanical cryocooler temperature control system is established,and the mathematical model of the mechanical cryocooler is modified.The corrected model simulation results are consistent with the experimental results and can be used to analyze the related features of the mechanical cryocooler temperature control system.Combined with the simplified calculation method of the stability domain parameter range,the stability range of the control parameters is given.The effects of thermal load change,ambient temperature change,and cold head temperature acquisition signal noise interference on the system stability performance are analyzed.Finally,the above theory and simulation results are verified by experiments,and the system control parameters are adjusted to make the mechanical cryocooler temperature control system achieve the performance index of ±25mK/30 min.