Design of a novel fractional‐order internal model controller‐based Smith predictor for integrating processes with large dead‐time
Deepak Kumar, Pulakraj Aryan, G. Lloyds Raja
Abstract
Abstract A novel multi‐loop control configuration with two controllers is suggested for integrating processes having large dead‐time. The inner‐loop consists of a Smith predictor having proportional (P)/proportional‐derivative (PD) controller for first/second‐order integrating processes, respectively. Once the dead‐time is compensated by the inner‐loop Smith predictor, a fractional‐order internal model controller (FOIMC) is designed in the outer‐loop. The P/PD controllers are tuned using direct synthesis methodology. The proposed control architecture has three adjustable parameters (inner and outer closed‐loop adjustment parameters, fractional‐order of the FOIMC low‐pass filter). Based on extensive simulations, the tuning ranges for the above‐mentioned adjustable parameters are specified. Suitable justification is also provided for the suggested range of tuning parameters. Several benchmark examples of plant models are used to study the set‐point following and disturbance elimination capabilities of the proposed control architecture. Quantitative performance measures are also computed for comparing the suggested and previously reported schemes. It is evident that the suggested FOIMC based Smith predictor yields enhanced control performance than some recently reported techniques.