Research On Internal Model Control For Multivariable Large Time Delay Systemes

In the process of material transmission,time delay exits in temperature control,pressure detection in industrial production.The time delay will seriously affects the control performance of the system.In addition,there are multi variables in the industrial process,and the interaction between the variables increases the difficulty of the controller design.To deal with the above problems,the paper starts with single-loop system and focuses on the analysis of frequency characteristics of internal model control system.Based on the phase margin of the system,the relative stability of the internal model control system is proved by mathematical derivation firstly.Besides,the paper gets the analytical relationship between the adjustable parameter and stability margin by discussing the phase margin and gain margin of IMC deeply.Thus,the controller parameter can be determined directly according to the desired phase margin and gain margin.In order to achieve the preferably control effect,the paper selects the specific phase margin and gain margin to determine the controller,and transforms the IMC into PID on this basis.The resulting PID controller can achieve the same control effect as IMC owing to no approximation method used in the conversion process.Moreover,a new two point modeling method is proposed for high order processes.The effectiveness of the proposed method is proved by simulation results.In multivariable system,this paper studied several existing decoupling method,and focuses on the analysis of inverse decoupling control principle.The application of the proposed analytical controller in multivariable system is presented:firstly,the inverse decoupling method is used to remove the coupling between the loops,and then the corresponding controller is designed for each loop.