不稳定大时滞过程的串级PID控制

The cascade PID control for unstable process with large time delay

针对一类不稳定大时滞过程,提出了一种基于内模控制(IMC)框架下改进的串级PID控制结构,给出了参数设计的一般准则。系统双闭环均按照IMC原理设计为经典反馈控制结构,内环控制器主要用于镇定不稳定对象和抑制主要干扰,外环用于改善系统性能。内外环控制器均只用一个调节参数,调节参数和对象参数与闭环系统性能解析关系明确。仿真表明,该方法能有效控制滞后时间与时间常数之比大于1的大时滞过程,鲁棒性强,结构设计和调节简单,适合工程应用。

A cascade PID control structure based on the framework of internal model control is introduced for a class of unstable process with large time delay. Some rules of parameter design are given. The two controllers which are designed according to the principle of IMC are of classical feedback controller structure. The inner one is used to stabilize the object and restrain the main disturbance while the outer one is used to improve the performance of the system. Each controller only uses one tuning parameter. The PID controllers＇ parameters have explicit expression with the plant parameters and the desired closed loop performance. The simulation results show some key benefits of this method： If time delay is comparable to （or larger than） the plant time constant, the closed loop still performs well and has better robustness to model errors. It is simple to design and adjust procedure and is good at engineering application.