Delay Stability Of The System Of Regional Analysis And Control Methods

Time delay, widely existing in industrial processes, is often one of the main causes ofperformance deterioration and even instability. Therefore, it has very important theoreticaland practical values to study the stability and control ways of time delay systems. In thispaper, PI controller, Internal Model Controller (IMC), Smith predictor and External ModelController (EMC), which are all based on model estimation, are deeply concluded for afirst order plus dead time plant. Details are provided about how to design the controllersseparately. Simulation examples are given to illustrate the proposed methods correctly andeffectively.This paper focuses on that Guillermo et al presented a solution to the complete set ofstabilizing FOPDT using PI controller firstly. In the practice, approximation simplifiedapproach has been adopted to get a stabilizing region of PI controller parameters basing ongain and phase margins (GPM). Then, the classical single input and single output (SISO)feedback control system is represented as its equivalent IMC. The controller is designedanalytically using specified GPM. Especially, the filter time constantλis found outrationally. Furthermore, Smith predictor is also designed basing on IMC principle for theunstable process with an enhanced structure. Finally, the structure of EMC is appropriatelychanged to simplify the design of controller and filter. Meantime, the measures improve therobustness of the control system.