Control of Compressor Surge in Systems with Uncertain Equilibrium States

This paper investigates the stabilization of nonlinear dynamic systems with uncertain equilibrium states. The control problem is motivated by the active control of compressor surge in compression systems with uncertainty in the characteristic curve, which maps the equilibrium operating states of the system flow. An adaptation mechanism is introduced for both the state and output feedback control cases, using information from the feedback control signal to determine the true equilibrium of the nonlinear plant. Conditions for the existence of such adaptation mechanism are presented, and stability of the closed-loop system is demonstrated by using singular perturbation analysis techniques. The effectiveness of the proposed adaptation mechanism is verified by using a high fidelity mathematical model of a compression system test rig that has been commissioned to test active surge control methods by active magnetic bearings.