基于Smith-Fuzzy-PID控制的艾叶精油超临界萃取温度控制系统研究

Supercritical extraction of wormwood oil based on Smith-Fuzzy-PID cotrol

艾叶精油超临界萃取生产过程中,温度是影响超临界萃取得率的最关键因素。温度控制系统滞后大、干扰因素多、参数易变的特点,使得常规PID温度控制在超临界萃取系统中的适应性差。针对超临界萃取系统的温度变量提出了Smith-Fuzzy-PID控制法,该方法在PID控制中加入Smith预估器,来补偿系统滞后;加入适应性较强的模糊控制用来及时调整PID参数。用MATLAB仿真从理论上验证了这种控制方法无超调、稳定快且鲁棒性好的特性。

In the production process of wormwood’s supercritical fluid extraction,Temperature is one of the most critical factors.The temperature control system is very nonlinear,time lagging a lot,with many interferential factors and prodigiously inertial.This results in the poor adaptability of conventional temperature PID control to the supercritical extraction system.In this paper,a Smith fuzzy PID control method is proposed to solve this problem.In the control method,Smith predictor is added to compensate the system lag,and that the adaptive fuzzy control is used to adjust PID parameters in time.It is proved by matlab simulation that this method has no overshoot and has the features of short stability time and good robustness.