Performance analysis of IMC based cascade control system and comparative study of 1DF & 2DF IMC controller

Abstract

In this project, performance analysis of IMC (Internal Model Control) based Cascade Control and comparative study of 1DF (One-Degree of Freedom) and 2DF (Two-Degree of Freedom) IMC controller has been discussed. Based on considerations about the expected operational modes of the inner loop as well as outer loop controller are selected from the 1DF and 2DF IMC control system. A design method for both 1DF and 2DF IMC systems have been designed with ideal models which provide the greatest probable performance compatible with noisy measurement for intrinsically stable processes. An important thing is that for designing of IMC controllers is the capability to show the time response of the loop transmission. The MATLAB and SIMULINK software has been used for designing of the 1FD and 2DF controllers, where the controllers and processes has been performed in the blocks. The 1DF control systems present the IMC design methods for intrinsically stable linear processes where the disturbance arrives directly into the process output. The 2DF control systems are used for stable processes or for inherently unstable processes where the disturbances proceeds over a lag or over a lag the process whose process time constants are in the order of lag time constants of the process or greater than the process lag time constant . In IMC cascade systems, to obtain the best set-point tracking and disturbance rejection the cascade control inner loop must be designed and tuned such as a 2DF controller