Enhanced fractional-order PI[formula omitted]D[formula omitted] control for a forced circulation evaporator system via advanced disturbance observer.

Strong disturbances, time delays, and coupling effects complicate the control of evaporator systems. In this paper, to overcome these difficulties a three-stage controller design is given and as a first step a disturbance observer (DOB) is designed. Then, fractional order PI λ D μ controllers (PI λ D μ FOC) with inverted decoupling structure are realized. Finally, PI λ D μ FOC is enhanced via DOB and applied to control of a considered forced circulation evaporator system. Controlling the evaporator system with the DOB-enhanced PI λ D μ FOC is showed more accurate and precise control results when compared with the optimally tuned PID and fuzzy logic controller (FLC). The DOB-enhanced PI λ D μ FOC method has remarkable superiority in disturbance rejection and the proposed control method is improved the tracking ability of the system for reference changes. • A disturbance observer (DOB) is designed to overcome strong disturbances on forced circulation evaporator control. • Fractional order PI λ D μ controllers (PI λ D μ FOC) with inverted decoupling structure are realized. • The designed PI λ D μ FOC is enhanced via disturbance observer. [ABSTRACT FROM AUTHOR]