Saturating PI Control of Stable Nonlinear Systems Using Singular Perturbations

This article presents an antiwindup propor- tional-integral (PI) controller, using a saturating integrator, for single-input and single-output (SISO) stable nonlinear plant, whose steady-state input–output map is increasing. We prove that, under reasonable assumptions, there exists upper bound on the controller gain such that any constant reference input, corresponding equilibrium point of closed-loop system exponentially stable, with “large” region attraction. When state converges to this point, then tracking error tends zero. The stability analysis employs Lyapunov methods in framework singular perturbations theory. Finally, we show if plant satisfies asymptotic property, globally asymptotically sufficiently small gain. effectiveness proposed PI proved by showing how it performs as part control algorithm synchronverter (a special type dc ac power converter).