Limit PID control method of multi input multi output system

Abstract

A method for controlling limit PID of multi-input / multi-output system includes identifying model as per transfer function matrix of multi-input / multi-output procedure, designing three optimum demodulation factors based on robust control theory, designing optimum controller based on said factors and optimum performance target, simplifying sub controller in controller matrix, obtaining output control signal by calculation and sending it to executor after D / A conversion to act it onto controlled object to let controlled object be operated in set range.

Description

technical field [0001] The invention relates to a method used in the technical field of industrial process control, in particular to a limit PID control method for a multi-input multi-output system. Background technique [0002] In order to solve the coupling problem of the multivariable system, the commonly used method is to decouple the multivariable system into multiple univariate systems, and then apply the control method of the univariate system to realize the multi-loop control, also known as the distributed control structure. Due to the advantages of simple structure, low cost and strong independent workability of each closed loop, it is widely used in chemical practice. However, the stability of this control structure is easily damaged by the uncertainty of the actual controlled process. In addition, when there is interference and uncoordinated control effects between each independent closed-loop control system in the multi-loop control structure, the system cannot a...

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Problems solved by technology

Due to the complexity of the multiple-input multiple-output system, the controller transfer function often contains irrational items or higher-order items through analytical methods, so that the controller form cannot be directly transformed into the form of a PID controller.

At present, there are approximation methods such as least squares, Pade approximation, and Taylor approximation to solve this kind of problem. However, due to the limitation of approximation accuracy, there is still a certain error between the approximated controller and the theoretical optimal controller.

[0003] Found through literature search to prior art, Yongho Lee et al published " PID controller tuning for desired closed loop response for SI / SO systems" (PID controller tuning method for ideal closed-loop response of single-input and single-output systems), this paper proposes a PID controller based on Maclaurin expansion (hereinafter referred to as Maclaurin PID control controller) design method, this method can achieve better system performance in theory, its shortcoming is that the specific controller parameter tuning method is not given in the article

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