Robust Anti-Windup Control Design for PID Controllers–Theory and Experimental Verification

Subject Areas :

Payam Kheirkhahan ¹

1 - Department of Electrical Engineering, Garmsar branch, Islamic Azad University, Garmsar, Iran

Received: 2017-10-03 Accepted : 2017-12-10 Published : 2017-08-01

Keywords: Back Calculation, Conditional integration, Limited Integrator, Preloading, Realizable Reference, Universal Approximator,

Abstract :

This paper addresses an approximation-based anti-windup (AW) control strategy for suppressingthe windup effect caused by actuator saturation nonlinearity in proportional–integral–derivative(PID) controlled systems. The effect of actuator constraint is firstly regarded as a disturbanceimported to the PID controller. The external disturbance can then be modeled by a linear differentialequation with unknown coefficients. Using Stone-Weierstrass theorem, it is verified that thesedifferential equations are universal approximators. An auxiliary control signal is finally designed tomodify the error signal injected to the PID controller. The proposed AW control scheme is simple,system independent and applicable by digital or analog circuits. Analytical studies as well asexperimental results using MATLAB/SIMULINK external mode, demonstrate high performance ofthe proposed approach. It is shown that the proposed AW scheme renders the performance of thecontrolled system more robust toward the effects of windup than conventional PID AW schemes.The stability analysis is provided by Lyapunov's second method.