Open AccessDesign of modified 2-degree-of-freedom proportional–integral–derivative controller for unstable processes
Author(s) -
Ziwei Li,
Zheng Xu,
Ridong Zhang,
Hongbo Zou,
Furong Gao
Publication year - 2020
Publication title -
measurement + control/measurement and control
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.286
H-Index - 21
eISSN - 2051-8730
pISSN - 0020-2940
DOI - 10.1177/0020294020944954
Subject(s) - feed forward , control theory (sociology) , controller (irrigation) , inner loop , control system , pid controller , loop (graph theory) , disturbance (geology) , tracking (education) , set (abstract data type) , computer science , control engineering , mathematics , engineering , control (management) , temperature control , artificial intelligence , psychology , paleontology , agronomy , pedagogy , electrical engineering , combinatorics , biology , programming language
Concerning first-order unstable processes with time delays that are typical in chemical processes, a modified 2-degree-of-freedom proportional–integral–derivative control method is put forward. The system presents a two-loop structure: inner loop and outer loop. The inner loop is in a classical feedback control structure with a proportional controller intended for implementing stable control of the unstable process; the outer loop is in a 2-degree-of-freedom structure with feedforward control of set points, where the system’s tracking response of set points is separated from its disturbance response. To be specific, the system has a feedforward controller that is designed based on the controlled object models and mainly used for regulating the system’s set point tracking characteristics; besides, it has a feedback controller that is designed on the ground of direct synthesis of disturbance suppression characteristics to improve the system’s disturbance rejection. To verify the effectiveness, the system is put into a theoretical analysis and simulated comparison with other methods. Simulation results show that the system has good set point tracking characteristics and disturbance suppression characteristics.