Design Of Gas Chromatograph Measurement Control System

Gas Chromatograph(GC) is a kind of analytical instruments, which is very important for people to use the performance of qualitative and quantitative analysis the mixture. Apart from taking about the influence factors of chemical, the control system performance of domestic GC lags behind that of foreign advanced GC. Therefore, it has important significance for GC to make the research and development of high precision control system so as to narrow the gap between domestic and foreign GC technology.Through studying the theory of GC and making the contrast research between the performance of domestic and foreign GC, we can get that temperature control precision is the main factors which is influencing the GC technology gap at home and abroad. So the design of high precision control system meeting the application requirements of high-performance GC is better way to narrow the gap between domestic and foreign GC technology. In the light of technical requirements of precise control system for GC, we adopt the modular thought and divide the system into multiple child module (power module, temperature control module, the detector module and flow pressure control module, etc.), and complete the final design and development. Based on switched delayed system which is established for GC column, we propose the theorem and corollary and give the LMI conditions for the robust stability of the temperature column oven, and use matlab software to make simulation of the theorem and corollary, the simulation results proves the validity and feasibility of the theorem and corollary.In order to improve the control precision of temperature control module, the switched delayed control strategy is adopted. Through analyzing the contrast experiment results of ordinary PID control method with switched delayed control strategy, considering that the strategy can effectively improve the control performance of the temperature module block, and satisfy the requirement of the temperature control of GC. To test the performance of temperature control of GC based on switched delayed system techniques, we make temperature programming. Through analyzing the temperature curve in detail, we can find that the performance indexes meet the requirements of the technical standards, and achieve the expected effect in this paper.